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Sample records for benzoapyrene diol epoxide

  1. Benzo(a)pyrene diol epoxides as intermediates in nucleic acid binding in vivo and in vitro

    DEFF Research Database (Denmark)

    Weinstein, I.B.; Jeffrey, A.M.; Jennette, K.W.; Blobstein, S.H.; Harvey, R.G.; Harris, C.; Autrup, Herman; Kasai, H.; Nakanishi, K.

    1976-01-01

    Evidence has been obtained that a specific isomer of a diol epoxide derivative of benzo(a)pyrene, (+/-)-7 beta,8alpha-dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, is an intermediate in the binding of benzo(a)pyrene to RNA in cultured bovine bronchial mucosa. An adduct is...

  2. Role of diaxial versus diequatorial hydroxyl groups in the tumorigenic activity of a benzo[a]pyrene bay-region diol epoxide.

    OpenAIRE

    Chang, R L; Wood, A.W.; Conney, A H; Yagi, H.; Sayer, J M; Thakker, D R; Jerina, D M; Levin, W

    1987-01-01

    Tumorigenic activities of the (7R,8S,9S,10R)-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro derivatives of benzo[a]pyrene [(+)-B[a]P diol epoxide-2] and 6-fluorobenzo[a]pyrene (6-FB[a]P diol epoxide-2) were evaluated in newborn CD-1 mice. A total dose of 14 nmol of either diol epoxide was administered to preweanling mice, and tumorigenic activity was determined when the mice were 32 to 36 weeks old. At the termination of the study, 13% of solvent-treated control mice had developed lung tumors w...

  3. Gene-specific repair of benzo[a]pyrene diol epoxide DNA damage in human cells

    International Nuclear Information System (INIS)

    Gene-specific preferential repair of UV damage has been well documented in a variety of organisms. Less is known about many other types of critical DNA lesions, the data available being not numerous and contradictory. To date, the majority of observations with UV were obtained by using T4 endonuclease V system. Recent report questions the applicability of UvrABC nuclease incision method for detecting gene-specific repair. This has stimulated our search for simple and sensitive approach based on a different principle. We have employed the idea of detection by the Southern hybridization of restriction cleavage inhibition at rare sites and developed a method for the analysis of benzo[a]pyrene diol epoxide (anti-BPDE) DNA damage in human H-ras proto-oncogene. Damage-dependent induction of individual facultative bands resulting from cleavage inhibition was observed in in vitro modified (4-50 adducts/103kb) p220-ras plasmid DNA digested with EcoRI/NotI, Xhol/Xbal/PstI, and SstI/XbaI/Pst/I. In vivo lesion formation and removal was monitored at several PstI sites distributed along the 6.4 kb single copy ras sequence. Rapid gene-specific repair was seen in primary culture of normal human fibroblasts and in SV40 transformed GM00637 cells. Surprisingly, SV40 transformed XP12BE (complementation group A) GM4429 fibroblasts also repaired anti-BPDE DNA damage at comparable levels. All investigated sites within ras sequence were repaired faster than the genome overall. The results show the utility of the above approach for fine mapping of anti-BPDE DNA lesions. Data suggests that the xeroderma pigmentosum (group A) fibroblasts have a capacity of removing these bulky adducts at least from the active genes

  4. BENZO(A)PYRENE DIOL EPOXIDE I BINDS TO DNA AT REPLICATION FORKS (JOURNAL VERSION)

    Science.gov (United States)

    The distribution in replication forks of DNA lesions caused by the treatment of S phase calls with benzo(a)pyrene-diol-epoxide-1 (BPDE-1) was studied in synchronized C3H10T1/2 cells. Sites of carcinogen modification of DNA were identified by polyclonal rabbit antibodies that were...

  5. Myeloperoxidase - 463A variant reduces benzo(a)pyrene diol epoxide DNA adducts in skin of coal tar treated patients

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, M.; Godschalk, R.; Alexandrov, K.; Cascorbi, I.; Kriek, E.; Ostertag, J.; Van Schooten, F.J.; Bartsch, H. [German Cancer Research Center, Heidelberg (Germany). Div. of Toxicology & Cancer Risk Factors

    2001-07-01

    The skin of atopic dermatitis patients provides an excellent model to study the role of inflammation in benzo(a)pyrene (BaP) activation, since these individuals are often topically treated with ointments containing high concentrations of BaP. The authors determined, by HPLC with fluorescence detection, the BaP diol epoxide (BPDE)-DNA adduct levels in human skin after topical treatment with coal tar and their modulation by the -453G into A myeloperoxidase (MPO) polymorphism, which reduces MPO mRNA expression. The data show for the first time: (i) the in vivo formation of BPDE-DNA adducts in human skin treated with coal tar; (ii) that the MPO-463AA/AG genotype reduced BPDE-DNA adduct levels in human skin.

  6. Mechanism of the inhibition of mutagenicity of a benzo[a]pyrene 7,8-diol 9,10-epoxide by riboflavin 5'-phosphate.

    OpenAIRE

    Wood, A.W.; Sayer, J M; Newmark, H L; Yagi, H.; Michaud, D P; Jerina, D M; Conney, A H

    1982-01-01

    Riboflavin 5'-phosphate (flavin mononucleotide; FMN) inhibits the mutagenicity of (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (B[a]P diol epoxide), the only known ultimate carcinogenic metabolite of benzo[a]pyrene. Coincubation of 10, 25, and 50 nmol of FMN with strain TA100 of histidine-dependent Salmonella typhimurium inhibits the mutagenicity of 0.05 nmol of the diol epoxide by 50, 70, and 90%, respectively. Ribose 5-phosphate and riboflavin sh...

  7. Illegitimate recombination induced by benzo[a]pyrene diol epoxide in Escherichia coli

    International Nuclear Information System (INIS)

    Duplex DNA oligomer constructs (32 base pairs) were paired that contained a single benzo[a]pyrene (BP) adduct at a specific deoxyadenosine or deoxyguanosine site in either one or both strands. These constructs were inserted into M13 replicative form viral DNA, and the DNA from progeny virus generated by transfection of Escherichia coli was examined by sequence analysis at the site of oligomer insertion. With nonalkylated constructs, and with constructs containing only one BP adduct, no sequence alterations were found in progeny viral DNAs. With constructs containing two BP adducts, one in each strand and closely spaced, some progeny DNAs showed the original oligomer sequence, whereas others exhibited large deletions and illegitimate (non-homologous) recombination, both of which removed the damage construct. Increasing the distance between BP adducts in the construct reduced the frequency of recombinant events. These sequence alterations occurred in both recA+ and recA- host cells. The authors speculate that the closely spaced adducts in opposite construct strands cause a rare distortion in DNA structure, which activates the recombinant machinery, and that mutagenic and carcinogenic agents other than polycyclic aromatic hydrocarbons may cause similar DNA distortions, which induce illegitimate recombination

  8. DNA polymerase eta participates in the mutagenic bypass of adducts induced by benzo[a]pyrene diol epoxide in mammalian cells.

    Directory of Open Access Journals (Sweden)

    Alden C Klarer

    Full Text Available Y-family DNA-polymerases have larger active sites that can accommodate bulky DNA adducts allowing them to bypass these lesions during replication. One member, polymerase eta (pol eta, is specialized for the bypass of UV-induced thymidine-thymidine dimers, correctly inserting two adenines. Loss of pol eta function is the molecular basis for xeroderma pigmentosum (XP variant where the accumulation of mutations results in a dramatic increase in UV-induced skin cancers. Less is known about the role of pol eta in the bypass of other DNA adducts. A commonly encountered DNA adduct is that caused by benzo[a]pyrene diol epoxide (BPDE, the ultimate carcinogenic metabolite of the environmental chemical benzo[a]pyrene. Here, treatment of pol eta-deficient fibroblasts from humans and mice with BPDE resulted in a significant decrease in Hprt gene mutations. These studies in mammalian cells support a number of in vitro reports that purified pol eta has error-prone activity on plasmids with site-directed BPDE adducts. Sequencing the Hprt gene from this work shows that the majority of mutations are G>T transversions. These data suggest that pol eta has error-prone activity when bypassing BPDE-adducts. Understanding the basis of environmental carcinogen-derived mutations may enable prevention strategies to reduce such mutations with the intent to reduce the number of environmentally relevant cancers.

  9. Preferential binding of benzo[a]pyrene diol epoxide to the linker DNA of human foreskin fibroblasts in S phase in the presence of benzamide.

    OpenAIRE

    Kurian, P.; Jeffrey, A M; Milo, G E

    1985-01-01

    Addition of benzamide (BZ) at the onset of S phase inhibited expression of the neoplastic phenotype in human foreskin fibroblasts treated in vitro with (+/-)-7 alpha,8 beta-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (B[a]P diol epoxide) in early S phase. Analysis of the specific B[a]P diol epoxide-DNA adducts revealed that ca. 65% of the total adducts in BZ and non-BZ carcinogen-treated cells was the B[a]P diol epoxide-deoxyguanine adduct. Limited micrococcal nuclease di...

  10. Preferential binding of benzo[a]pyrene diol epoxide to linker DNA of human foreskin fibroblasts in S phase in the presence of benzamide

    International Nuclear Information System (INIS)

    Addition of benzamide (BZ) at the onset of S phase inhibited expression of the neoplastic phenotype of human foreskin fibroblasts treated in vitro with (+/-)-7α,8β-dihydroxy-9β,10β-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (B[a]P diol epoxide) in early S phase. Analysis of the specific B[a]P diol epoxide-DNA adducts revealed that ca. 65% of the total adducts in BZ and non-BZ carcinogen-treated cells was the B[a]P diol epoxide-deoxyguanine adduct. Limited micrococcal nuclease digestion of the early S phase nuclei from cells treated with B[a]P diol epoxide indicated that the carcinogen binds equally to linker and core DNA. However, when the cells were predominantly in S phase, in the presence of BZ, there was ca. three times more binding of B[a]P diol epoxide to the linker DNA compared to the core region. These data indicate that pretreatment of the cells with BZ at the onset of S phase established a preferential binding pattern in the linker DNA similar to that observed in the cells treated with B[a]P diol epoxide in G1 arrest

  11. Serum Level of Antibody against Benzo[a]pyrene-7,8-diol-9,10-epoxide-DNA Adducts in People Dermally Exposed to PAHs

    Directory of Open Access Journals (Sweden)

    Lenka Borska

    2014-01-01

    Full Text Available Some specific antibodies indicate the presence of antigenic structures on DNA (DNA adducts that can play an important role in the process of mutagenesis and/or carcinogenesis. They indicate the presence of increased genotoxic potential (hazard prior to the formation of disease (primary prevention. The present study was focused on the serum level of benzo[a]pyrene 7,8-diol-9,10-epoxide-DNA adducts antibodies (anti-BPDE-DNA in psoriatic patients (n=55 dermally exposed to different levels of polycyclic aromatic hydrocarbons (PAHs. The general goal of the study was to contribute to better understanding of the value of the assumed biomarker (anti-BPDE-DNA for evaluation of the organism's answer to genotoxic exposure to PAHs. Elevated level of exposure to PAHs resulted in the increased level of anti-BPDE-DNA. However, almost all levels of anti-BPDE-DNA ranged within the field of low values. Both variants of GT (CCT-3% and CCT-5% induced higher expression of anti-BPDE-DNA in the group of nonsmokers. Significant relations between the level of anti-BPDE-DNA and PASI score, total duration of the therapy, or time of UVR exposure were not found. Further studies are needed to reduce interpretation uncertainty of this promising bioindicator.

  12. BENZO[A]PYRENE AND BENZO[C]PHENANTHRENE: THE EFFECT OF STRUCTURE ON THE BINDING OF WATER MOLECULES TO THE DIOL EPOXIDES

    Science.gov (United States)

    ABSTRACTThe interaction with water of the diol epoxides (DEs) of both a planar and a non-planar PAH have been examined using molecular dynamics. To determine probable water locations around the DE for later use in the study of DE protonation, molecular dynamics simulations u...

  13. Gene expression profiles and genetic damage in benzo(a)pyrene diol epoxide-exposed TK6 cells

    International Nuclear Information System (INIS)

    Microarray analysis is a powerful tool to identify the biological effects of drugs or chemicals on cellular gene expression. In this study, we compare the relationships between traditional measures of genetic toxicology and mutagen-induced alterations in gene expression profiles. TK6 cells were incubated with 0.01, 0.1, or 1.0 μM ±anti-benzo(a)pyrene-trans-7,8-dihydrodiol-9,10-epoxide (BPDE) for 4 h and then cultured for an additional 20 h. Aliquots of the exposed cells were removed at 4 and 24 h in order to quantify DNA adduct levels by 32P post-labeling and measure cell viability by cloning efficiency and flow cytometry. Gene expression profiles were developed by extracting total RNA from the control and exposed cells at 4 and 24 h, labeling with Cy3 or Cy5 and hybridizing to a human 350 gene array. Mutant frequencies in the Thymidine Kinase and Hypoxanthine Phosphoribosyl Transferase genes were also determined. The 10α-(deoxyguanosin-N2-yl)-7α,8β,9β-trihydroxy-7,8,9,10-tetrahydrobenzo(a) pyrene (dG-N2-BPDE) adduct increased as a function of dose and was the only adduct identified. A dose-related decrease in cell viability was evident at 24 h, but not at 4 h. Cell death occurred by apoptosis. At 4 h, analysis of the gene expression profiles revealed that Glutathione Peroxidase and Gadd45 were consistently upregulated (greater than 1.5-fold and significantly (P<0.001) greater than the control in two experiments) in response to 1.0 μM BPDE exposure. Fifteen genes were consistently down-regulated (less than 0.67-fold and significantly (P<0.001) lower than the control in two experiments) at 4 h in cultures exposed to 1.0 μM BPDE. Genes with altered expression at 4 h included genes important in the progression of the cell-cycle and those that inhibit apoptosis. At 24 h post-exposure, 16 genes, involved in cell-cycle control, detoxification, and apoptosis were consistently upregulated; 10 genes were repressed in cultures exposed to the high dose of BPDE. Real

  14. Epigallocatechin-3-gallate reduces DNA damage induced by benzo[a]pyrene diol epoxide and cigarette smoke condensate in human mucosa tissue cultures.

    Science.gov (United States)

    Baumeister, Philipp; Reiter, Maximilian; Kleinsasser, Norbert; Matthias, Christoph; Harréus, Ulrich

    2009-06-01

    Although epidemiological studies indicate cancer preventive effects of diets rich in fruit and vegetables, large clinical intervention studies conducted to evaluate dietary supplementation with micronutrients, mostly vitamins, showed disappointing results in large parts. In contrast, there is encouraging epidemiologic data indicating great chemopreventive potential of a large group of phytochemicals, namely polyphenols. This study shows the DNA protective effect epigallocatechin-3-gallate, a tea catechin, and one of the best-studied substances within this group, on carcinogen-induced DNA fragmentation in upper aerodigestive tract cells. Cell cultures from fresh oropharyngeal mucosa biopsies were preincubated with epigallocatechin-3-gallate in different concentrations before DNA damage was introduced with the metabolically activated carcinogen benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide or cigarette smoke condensate. Effects on resulting DNA fragmentation were measured using the alkaline single-cell microgel electrophoresis (comet assay). Epigallocatechin-3-gallate significantly reduced benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide-induced DNA damage by up to 51% (Pculture model. PMID:19491610

  15. The role of hRev7, the accessory subunit of hPolζ, in translesion synthesis past DNA damage induced by benzo[a]pyrene diol epoxide (BPDE

    Directory of Open Access Journals (Sweden)

    Maher Veronica M

    2010-12-01

    Full Text Available Abstract Background DNA polymerase zeta (Polζ is a specialized DNA polymerase that, unlike classical replicative polymerases, is capable of replicating past DNA lesions, i.e. of performing translesion synthesis (TLS. The catalytic subunit of hPolζ, hRev3, has been shown to play a critical role in DNA damage-induced mutagenesis in human cells, but less is known about the role of hRev7, the accessory subunit of hPolζ, in such mutagenesis. To address this question, we recently generated human fibroblasts with very significantly reduced levels of hRev7 protein and demonstrated that hRev7 is required to protect cells from ultraviolet(254 nm (UV radiation-induced cytotoxicity and mutagenesis (McNally et al., DNA Repair 7 (2008 597-604. The goal of the present study was to determine whether hRev7 is similarly involved in the tolerance of DNA damage induced by benzo[a]pyrene diol epoxide (BPDE, the reactive form of the widespread environmental carcinogen benzo[a]pyrene. Methods To determine whether hRev7 also plays a role in protecting human cells from the cytotoxicity and mutagenesis induced by benzo[a]pyrene diol epoxide (BPDE, cell strains with reduced hRev7 were compared to their parental strain and a vector control strain for the effect of BPDE on cell survival, induction of mutations, and the ability to progress through the cell cycle. Results The results show that cell strains with reduced hRev7 are more sensitive to the cytotoxic effect of BPDE than the control strains, and progress through S-phase at a slower rate than the control cells following BPDE treatment, indicating that hRev7, and likely hPolζ, is required for efficient bypass of BPDE-induced DNA lesions. However, neither the frequency nor kinds of mutations induced by BPDE in cells with reduced hRev7 differ significantly from those induced in the control strains, suggesting that hPolζ is not essential for inserting nucleotides opposite BPDE-induced DNA damage. Conclusions Taken

  16. Benzo[a]pyrene diol epoxide suppresses retinoic acid receptor-β2 expression by recruiting DNA (cytosine-5--methyltransferase 3A

    Directory of Open Access Journals (Sweden)

    Xu Xiao-Chun

    2010-04-01

    Full Text Available Abstract Tobacco smoke is an important risk factor for various human cancers, including esophageal cancer. How benzo [a]pyrene diol epoxide (BPDE, a carcinogen present in tobacco smoke as well as in environmental pollution, induces esophageal carcinogenesis has yet to be defined. In this study, we investigated the molecular mechanism responsible for BPDE-suppressed expression of retinoic acid receptor-beta2 (RAR-β2 in esophageal cancer cells. We treated esophageal cancer cells with BPDE before performing methylation-specific polymerase chain reaction (MSP to find that BPDE induced methylation of the RAR-β2 gene promoter. We then performed chromatin immunoprecipitation (ChIP assays to find that BPDE recruited genes of the methylation machinery into the RAR-β2 gene promoter. We found that BPDE recruited DNA (cytosine-5--methyltransferase 3 alpha (DNMT3A, but not beta (DNMT3B, in a time-dependent manner to methylate the RAR-β2 gene promoter, which we confirmed by reverse transcription-polymerase chain reaction (RT-PCR analysis of the reduced RAR-β2 expression in these BPDE-treated esophageal cancer cell lines. However, BPDE did not significantly change DNMT3A expression, but it slightly reduced DNMT3B expression. DNA methylase inhibitor 5-aza-2'-deoxycytidine (5-Aza and DNMT3A small hairpin RNA (shRNA vector antagonized the effects of BPDE on RAR-β2 expressions. Transient transfection of the DNMT3A shRNA vector also antagonized BPDE's effects on expression of RAR-β2, c-Jun, phosphorylated extracellular signal-regulated protein kinases 1/2 (ERK1/2, and cyclooxygenase-2 (COX-2, suggesting a possible therapeutic effect. The results of this study form the link between the esophageal cancer risk factor BPDE and the reduced RAR-β2 expression.

  17. Detection of benzo[a]pyrene diol epoxide-DNA adducts in peripheral blood lymphocytes and antibodies to the adducts in serum from coke oven workers.

    OpenAIRE

    Harris, C. C.; Vahakangas, K.; Newman, M J; Trivers, G E; Shamsuddin, A; Sinopoli, N; Mann, D L; Wright, W. E.

    1985-01-01

    Coke oven workers are exposed to high levels of carcinogenic polycyclic aromatic hydrocarbons, including benzo[a]pyrene (B[a]P), and are at increased risk of lung cancer. Since B[a]P is enzymatically activated to 7 beta,8 alpha-dihydroxy(9 alpha, 10 alpha)epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (B[a]PDE) that forms adducts with DNA, the presence of these adducts was measured in DNA from peripheral blood lymphocytes by synchronous fluorescence spectrophotometry and enzyme radioimmunoassay. App...

  18. COMPARATIVE STUDIES OF THE EFFECT OF POLYCYCLIC AROMATIC HYDROCARBON GEOMETRY ON THE HYDROLYSIS OF DIOL EPOXIDES

    Science.gov (United States)

    Comparative studies of the effect of polycyclic aromatic hydrocarbon geometry on the hydrolysis of diol epoxides The interaction of the diol epoxides (DEs) of both planar and non-planar PAHs with water have been examined using quantum mechanical and molecular dynamics. Th...

  19. Mutagenicity and tumorigenicity of the four enantiopure bay-region 3,4-diol-1,2-epoxide isomers of dibenz[a,h]anthracene

    OpenAIRE

    Chang, Richard L.; Wood, Alexander W.; Huang, Mou Tuan; Xie, Jian Guo; Cui, Xiao Xing; Reuhl, Kenneth R.; Boyd, D. R.; Lin, Yong; Shih, Weichung Joe; Balani, Suresh K.; Yagi, Haruhiko; Jerina, Donald M.; Conney, Allan H.

    2013-01-01

    Each enantiomer of the diastereomeric pair of bay-region dibenz[a,h]anthracene 3,4-diol-1,2-epoxides in which the benzylic 4-hydroxyl group and epoxide oxygen are either cis (isomer 1) or trans (isomer 2) were evaluated for mutagenic activity. In strains TA 98 and TA 100 of Salmonella typhimurium, the diol epoxide with (1S,2R,3S,4R) absolute configuration [(–)-diol epoxide-1] had the highest mutagenic activity. In Chinese hamster V-79 cells, the diol epoxide with (1R,2S,3S,4R) absolute con...

  20. Polyols Prepared from Ring-Opening Epoxidized Soybean Oil by a Castor Oil-Based Fatty Diol

    OpenAIRE

    Jing Zhang; Ji Jun Tang; Jiao Xia Zhang

    2015-01-01

    Several biorenewable vegetable oil-based polyols with different molecular weights and various hydroxyl functionalities were successfully prepared by ring-opening epoxidized soybean oil with a castor oil-based fatty diol. It was found that several factors, including reaction time, reaction temperature, and molar ratios between epoxidized soybean oil and castor oil diol, affect structures and rheology behaviors of the final polyols. Proton NMR, FT-IR, GPC, and rheometry results revealed that th...

  1. NMR solution structures of adducts derived from the binding of polycyclic aromatic diol epoxides to DNA

    Energy Technology Data Exchange (ETDEWEB)

    Cosman, M.; Patel, D.J. [Memorial Sloan Kettering Cancer Center, New York, NY (United States). Cellular Biochemistry and Biophysics Program; Hingerty, B.E. [Oak Ridge National Lab., TN (United States). Health and Safety Research Div.; Amin, S. [American Health Foundation, Valhalla, NY (United States); Broyde, S.; Geacintov, N.E. [New York Univ., NY (United States)

    1995-12-31

    Site-specifically modified oligonucleotides were derived from the reactions of stereoisomeric polycyclic aromatic diol epoxide metabolite model compounds with oligonucleotides of defined base composition and sequence. The NMR solution structures of ten different adducts studied so far are briefly described, and it is shown that stereochemical factors and the nature of the oligonucleotide context of the complementary strands, exert a powerful influence on the conformational features of these adducts.

  2. Metabolic activation and DNA binding of benzo(a)pyrene in cultured human bronchus

    DEFF Research Database (Denmark)

    1977-01-01

    predominant metabolite formed by human bronchus from the (-)-trans-7,8-diol is found by high-pressure liquid chromatographic analysis to be the diol-epoxide r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahy-drobenzo(a)pyrene. The results suggest that this diol-epoxide is the major benzo(a)pyrene metabolite bound...

  3. Preferential Glutathione Conjugation of a Reverse Diol Epoxide Compared to a Bay Region Diol Epoxide of Phenanthrene in Human Hepatocytes: Relevance to Molecular Epidemiology Studies of Glutathione-S-Transferase Polymorphisms and Cancer

    OpenAIRE

    Hecht, Stephen S.; Berg, Jeannette Zinggeler; Hochalter, J. Bradley

    2009-01-01

    Bay region diol epoxides are recognized ultimate carcinogens of polycyclic aromatic hydrocarbons (PAH), and in vitro studies have demonstrated that they can be detoxified by conjugation with glutathione, leading to the widely investigated hypothesis that individuals with low activity forms of glutathione-S-transferases are at higher risk of PAH induced cancer, a hypothesis that has found at most weak support in molecular epidemiology studies. A weakness in this hypothesis was that the mercapt...

  4. Inhibition of benzopyrene-diol-epoxide (BPDE)-induced bax and caspase-9 by cadmium: Role of mitogen activated protein kinase

    International Nuclear Information System (INIS)

    Cadmium, a major metal constituent of tobacco smoke, elicits synergistic enhancement of cell transformation when combined with benzo[a]pyrene (BP) or other polynuclear aromatic hydrocarbons (PAHs). The mechanism underlying this synergism is not clearly understood. Present study demonstrates that (+/-)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), an ultimate carcinogen of BP, induces apoptosis in human leukemic HL-60 cells and others, and cadmium at non-cytotoxic concentration inhibits BPDE-induced apoptosis. We observed that BPDE treatment also activates all three MAP kinases e.g. ERK1/2, p38 and JNK in HL-60 cells, and inhibition of BPDE-induced apoptosis by cadmium is associated with down-regulation of pro-apoptotic bax induction/caspase-9 activation and up-regulation of ERK phosphorylation, whereas p38 MAP kinase and c-Jun phosphorylation (indicative of JNK activation) remain unaffected. Inhibition of ERKs by prior treatment of cells with 10 μM U0126 relieves cadmium-mediated inhibition of apoptosis/bax induction/caspase-9 activation. Our results suggest that cadmium inhibits BPDE-induced apoptosis by modulating apoptotic signaling through up-regulation of ERK, which is known to promote cell survival

  5. SEPARATION OF 32P-LABELED 3',5'-BISPHOSPHATE NUCLEOTIDES OF POLYCYCLIC AROMATIC HYDROCARBON ANTI-DIOL-EPOXIDES AND DERIVATIVES

    Science.gov (United States)

    23P-Postlabeling/HPLC is a highly sensitive analytical method for identification of chemical-modified DNA adducts isolated from experimental animals and human samples. o determine the optimal 32P-postlabeling/HPLC conditions for efficient separation, we employed ten diol-epoxide-...

  6. Flow cytometric measurement of the metabolism of benzo[a]pyrene by mouse liver cells in culture

    International Nuclear Information System (INIS)

    The metabolism of benzo[a]pyrene in individual cells was monitored by flow cytometry. The measurements are based on the alterations that occur in the fluorescence emission spectrum of benzo[a]pyrene when it is converted to various metabolites. Using present instrumentation the technique could easily detect 1x106 molecules per cells of benzo[a]pyrene and 1x107 molecules per cell of the diol epoxide. The analysis of C3H IOT 1/2 mouse fibroblasts growing in culture indicated that there was heterogeneity in the conversion of the parent compound into diol epoxide derivatives suggesting that some variation in sensitivity to transformation by benzo[a]pyrene may be due to differences in cellular metabolism. The technique allows sensitive detection of metabolites in viable cells, and provides a new approach to the study of factors that influence both metabolism and transformation. (orig.)

  7. Biocatalytic conversion of epoxides

    NARCIS (Netherlands)

    de Vries, Erik; Janssen, DB

    2003-01-01

    Epoxides are attractive intermediates for producing chiral compounds. Important biocatalytic reactions involving epoxides include epoxide hydrolase mediated kinetic resolution, leading to the formation of diols and enantiopure remaining substrates, and enantioconvergent enzymatic hydrolysis, which g

  8. BENZO[A]PYRENE AND ITS K-REGION DIOL INDUCE DNA DAMAGE IN C3H10T1/2C18 CELLS AS MEASURED BY THE ALKALINE SINGLE CELL GEL (COMET) ASSAY

    Science.gov (United States)

    160. Benzo[a]pyrene and its K-region diol induce DNA damage in C3HlOTl/2Cl8 cells as measured by the alkaline single cell gel (Comet) assay In a continuing series of studies on the genotoxicity ofK-region dihydrodiols of polycyclic aromatic hydrocarbons, we have repo...

  9. Characterization of the SgcF epoxide hydrolase supporting an (R)-vicinal diol intermediate for enediyne antitumor antibiotic C-1027 biosynthesis.

    Science.gov (United States)

    Lin, Shuangjun; Horsman, Geoffrey P; Chen, Yihua; Li, Wenli; Shen, Ben

    2009-11-18

    C-1027 is a chromoprotein antitumor antibiotic consisting of an apoprotein and the C-1027 chromophore. The C-1027 chromophore possesses four distinct structural moieties-an enediyne core, a deoxy aminosugar, a benzoxazolinate, and an (S)-3-chloro-5-hydroxy-beta-tyrosine-the latter two of which are proposed to be appended to the enediyne core via a convergent biosynthetic strategy. Here we report the in vitro characterization of SgcF, an epoxide hydrolase from the C-1027 biosynthetic gene cluster that catalyzes regio- and stereospecific hydrolysis of styrene oxide, serving as an enediyne core epoxide intermediate mimic, to form a vicinal diol. Abolishment of C-1027 production in the DeltasgcF mutant strain Streptomyces globisporus SB1010 unambiguously establishes that sgcF plays an indispensable role in C-1027 biosynthesis. SgcF efficiently hydrolyzes (S)-styrene oxide, displaying an apparent K(m) of 0.6 +/- 0.1 mM and k(cat) of 48 +/- 1 min(-1), via attack at the alpha-position to exclusively generate the (R)-phenyl vicinal diol, consistent with the stereochemistry of the C-1027 chromophore. These findings support the role of SgcF in the proposed convergent pathway for C-1027 biosynthesis, unveiling an (R)-vicinal diol as a key intermediate. Interestingly, SgcF can also hydrolyze (R)-styrene oxide to afford preferentially the (R)-phenyl vicinal diol via attack at the beta-position, albeit with significantly reduced efficiency (apparent K(m) of 2.0 +/- 0.4 mM and k(cat) = 4.3 +/- 0.3 min(-1)). Although the latter activity unlikely contributes to C-1027 biosynthesis in vivo, such enantioconvergence arising from complementary regioselective hydrolysis of a racemic substrate could be exploited to engineer epoxide hydrolases with improved regio- and/or enantiospecificity. PMID:19856960

  10. Benzo(a)pyrene diolepoxide-DNA adducts detected by synchronous fluorescence spectrophotometry.

    OpenAIRE

    Vahakangas, K.; Trivers, G; Rowe, M.; Harris, C. C.

    1985-01-01

    Using benzo(a)pyrene (BP) as a model carcinogen we are currently applying a fluorescence technique to detect the very low levels of carcinogen-DNA adducts in human populations due to environmental exposure. In synchronous fluorescence spectrophotometry for detection of BP-diol epoxide-DNA, excitation and emission wavelengths are scanned simultaneously with a fixed wavelength difference (delta lambda) of 34 nm. Compared to conventional fluorescence methods only one peak emerges because excitat...

  11. Development and validation of SPE-HPLC method for the determination of carbamazepine and its metabolites carbamazepine epoxide and carbamazepine trans-diol in plasma

    Directory of Open Access Journals (Sweden)

    Spasić Mirjana

    2012-01-01

    Full Text Available SPE-HPLC method has been developed and validated for rapid analysis of carbamazepine and its two metabolites carbamazepine epoxide and carbamazepine trans-diol in human plasma. The analysis was performed using C18 Bakerbond-BDC analytical column (250 mm x 4.6 mm i.d., particle size 5 μm. The optimal conditions for the separation were established with the mobile phase acetonitrile - 10 mM phosphate buffer, pH 7.0 (30:70, v/v at the flow rate of 1.5 mL min-1, temperature 35°C, and UV detection at 210 nm. Total run time was about 8 minutes. SPE procedure for extraction of the analytes from plasma sample was developed using Oasis HLB cartridges and subsequently eluate was injected into the HPLC system for analysis. Afterwards, SPE-HPLC method was subjected to validation. Linearity was obtained over the concentration range of 0.2-25 μg/mL for carbamazepine, carbamazepine epoxide and carbamazepine trans-diol with correlation coefficients higher than 0.995. The method showed good intra-day and inter-day precision with relative standard deviation below 7.96%, while accuracy ranged from 92.09% to 108.5% for all analytes. Finally, the method was successfully applied to analysis of plasma samples of epileptic patients in monotherapy and polytherapy. [Acknowledgments. Projekat Ministarstva nauke Republike Srbije, br. OI 172033].

  12. Preferential Formation of Benzo[a]pyrene Adducts at Lung Cancer Mutational Hotspots in P53

    Science.gov (United States)

    Denissenko, Mikhail F.; Pao, Annie; Tang, Moon-Shong; Pfeifer, Gerd P.

    1996-10-01

    Cigarette smoke carcinogens such as benzo[a]pyrene are implicated in the development of lung cancer. The distribution of benzo[a]pyrene diol epoxide (BPDE) adducts along exons of the P53 gene in BPDE-treated HeLa cells and bronchial epithelial cells was mapped at nucleotide resolution. Strong and selective adduct formation occurred at guanine positions in codons 157, 248, and 273. These same positions are the major mutational hotspots in human lung cancers. Thus, targeted adduct formation rather than phenotypic selection appears to shape the P53 mutational spectrum in lung cancer. These results provide a direct etiological link between a defined chemical carcinogen and human cancer.

  13. Binding, distribution, and clearance of 3H-benzo(a)pyrene-7,8-diol-9,10-epoxide from chromosomes of CHO cells

    International Nuclear Information System (INIS)

    The purpose of this study was to determine if the binding of a chemical carcinogen was random both within and between chromosomes. Chinese hamster ovary cells were exposed to 3H-labeled +/- anti[G-3H]-benzo(a)pyrene-7,8-diol-9,10-epoxide (3H-BPDE) and serially harvested. Autoradiographs were prepared and the distribution of silver grains over metaphase chromosomes was determined. The 3H-BPDE was randomly distributed down the length of the chromosome. The 3H-BPDE was rapidly removed from the chromosomes with 6% of the initial label remaining at 9 h after exposure. The distribution of silver grains between chromatids was nonrandom at 3 and 6 h after exposure, suggesting a differential removal of 3H-BPDE. 4 references, 4 figures

  14. The solid-matrix phosphorescence of (±)-anti-dibenzo[a,l]pyrene diol epoxide-DNA adducts and benzo[e]pyrene

    International Nuclear Information System (INIS)

    New solid-matrix phosphorescence (SMP) methods for (±)-anti-DB[a,l]PDE-DNA adducts and B[e]P were developed. The methods can be used to detect and characterize (±)-anti-DB[a,l]PDE-DNA adducts and B[e]P by employing SMP spectra, intensities, and lifetimes acquired with the heavy-atom salt, TlNO3, on Whatman 1PS paper. With the SMP data, a number of photophysical parameters were calculated such as biexponential SMP decay curves, pre-exponential factors, and fractional contribution to SMP decay curves. The SMP results were compared with earlier SMP data for (±)-anti-BPDE-DNA adducts and tetrol I-1. The SMP results show that small molecular-weight compounds like B[e]P can be readily detected and characterized by SMP. For example, the limit of detection for B[e]P was 0.60 pmol. Comparison of the SMP properties of the (±)-anti-DB[a,l]PDE-DNA adducts with earlier SMP data for the (±)-anti-BPDE-DNA adducts showed major differences in the SMP spectra, intensities, and lifetimes. The methods developed are important for the comparison of the SMP properties of different diol epoxides of PAH bonded to DNA

  15. 5-Methylchrysene metabolism in mouse epidermis in vivo, diol epoxide--DNA adduct persistence, and diol epoxide reactivity with DNA as potential factors influencing the predominance of 5-methylchrysene-1,2-diol-3,4-epoxide--DNA adducts in mouse epidermis

    International Nuclear Information System (INIS)

    5-Methylchrysene (5-MeC) can form two bay region dihydrodiol epoxides: 1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydro-5-methylchrysene (DE-I) which has the methyl group and the epoxide ring in the same bay region, and 7,8-dihydroxy-9,10-epoxy-7,8,10-tetrahydro-5-methylchrysene (DE-II). In a previous study, we observed that the ratio of DE-I:DNA adducts to DE-II:DNA adducts in mouse epidermis, 24 h after application of [3H]5-MeC metabolites was 2.7 to 1. To investigate the basis for this observation we have now studies: (i) the formation of [3H]5-MeC in mouse epidermis in vivo at various time intervals from 0.33 to 24 h; (ii) the persistence of DE-I:DNA adducts and DE-II:DNA adducts in mouse epidermis at 4-48 h after application of [3H]5-MeC; and (iii) the reactions of DE-I and DE-II with calf thymus DNA in vitro. In contrast to results obtained with mouse liver 9000 grams supernatant, the dihydrodiol precursors of DE-I and DE-II were present in equivalent quantities in mouse epidermis in vivo at every time point studied. The ratio of DE-I:DNA adducts to DE-II:DNA adducts in mouse epidermis was constant throughout the time period studied. However, the extent of formation of DE-I:DNA adducts was greater than that of DE-II:DNA adducts upon reaction of DE-I or DE-II with calf thymus DNA in vitro. These results suggest that differences in reactivity with DNA of DE-I and DE-II may bw responsible for the higher levels in mouse epidermis of DE-I:DNA adducts compared with DE-II:DNA adducts and provide a possible basis for the observed enhancing effect of a bay region methyl group on the carcinogenicity of polynuclear aromatic hydrocarbons

  16. Valpromide inhibits human epoxide hydrolase.

    OpenAIRE

    Pacifici, G. M.; Franchi, M; Bencini, C; Rane, A

    1986-01-01

    The effect of antipileptic drug valpromide (VPM) on the activity of epoxide hydrolase was studied in human adult and foetal liver, kidneys, lungs, intestine and in placenta. The activity of the epoxide hydrolase was measured with both styrene oxide and benzo(a)pyrene-4,5-oxide as substrates. VPM inhibited the epoxide hydrolase obtained from all organs studied. The degree of inhibition was independent of the substrate used. A lowering of the epoxide hydrolase activity by 50% was observed when ...

  17. hREV3 is essential for error-prone translesion synthesis past UV or benzo[a]pyrene diol epoxide-induced DNA lesions in human fibroblasts

    International Nuclear Information System (INIS)

    In S. cerevisiae, the REV3 gene, encoding the catalytic subunit of polymerase zeta, is involved in translesion synthesis and required for the production of mutations induced by ultraviolet radiation (UV) photoproducts and other DNA fork-blocking lesions, and for the majority of spontaneous mutations. To determine whether hREV3, the human homolog of yeast REV3, is similarly involved in error-prone translesion synthesis past UV photoproducts and other lesions that block DNA replication, an hREV3 antisense construct under the control of the TetP promoter was transfected into an infinite life span human fibroblast cell strain that expresses a high level of tTAk, the activator of that promoter. Three transfectant strains expressing high levels of hREV3 antisense RNA were identified and compared with their parental cell strain for sensitivity to the cytotoxic and mutagenic effects of UV. The three hREV3 antisense-expressing cell strains were not more sensitive than the parental strain to the cytotoxic effect of UV, but the frequency of mutants induced by UV in their HPRT gene was significantly reduced, i.e. to 14% that of the parent. Two of these hREV3 antisense-expressing cell strains were compared with the parental strain for sensitivity to (±)-7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE). They were not more sensitive than the parent strain to the cytotoxic effect of BPDE, but the frequency of mutants induced was significantly reduced, i.e. in one strain, to 17% that of the parent, and in the other, to 24%. DNA sequencing showed that the kinds of mutations induced by BPDE in the parental and the derivative strains did not differ and were similar to those found previously with finite life span human fibroblasts. The data strongly support the hypothesis that hRev3 plays a critical role in the induction of mutations by UV or BPDE. Because the level of hRev3 protein in human fibroblasts is below the level of antibody detection, it was not possible to demonstrate that the decrease in mutagenesis reflected decreased hRev3 protein. However, the conclusion is supported by the fact that in a similar study with a strain expressing a high level of antisense hREV1, a very similar result was obtained, i.e. UV or BPDE mutagenesis was virtually eliminated.

  18. The roles of diol epoxide and o-quinone pathways in mouse lung tumorigenesis induced by benzo(a)pyrene: relevance to human lung carcinogenesis

    Science.gov (United States)

    There is sufficient epidemiological evidence supported by experimental data that some PAH-containing complex environmental mixtures pose risks to human health by increasing lung cancer incidence. The International Agency for Research on Cancer has determined that human respirator...

  19. A novel AlEt3-promoted tandem reductive rearrangement of 1-benzyloxy-2,3-epoxides: new route to 2-quaternary 1,3-diol units.

    Science.gov (United States)

    Li, De Run; Xia, Wu Jiong; Tu, Yong Qiang; Zhang, Fu Min; Shi, Lei

    2003-03-21

    A novel and highly stereoselective tandem rearrangement-reduction reaction of 1-benzyloxy-2,3-epoxide, under the promotion of triethylaluminum (AlEt3), has been developed to construct a quaternary stereocenter and the hydroxymethyl attached to the carbon center in one-step. PMID:12703829

  20. Epoxidation and Reduction of DHEA, 1,4,6-Androstatrien-3-one and 4,6-Androstadien-3β,17β-diol

    Directory of Open Access Journals (Sweden)

    Eunjeong Kim

    2005-05-01

    Full Text Available Dehydroepiandrosterone (DHEA reacted with m-chloroperoxybenzoic acid(m-CPBA to form 3β-hydroxy-5α,6α-epoxyandrostan-17-one (1, but it did not reactwith 30% H2O2. 1,4,6-Androstatrien-3,17-dione (2 was obtained from DHEA and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in dioxane. Compound 2 was reacted with 30%H2O2 and 5% NaOH in methanol to give 1α,2α-epoxy-4,6-androstadien-3,17-dione (3,which was stereoselectively reduced with NaBH4 to form 1α,2α-epoxy-4,6-androstadien-3β,17β-diol (7 and reacted with Li metal in absolute ethanol-tetrahydrofuran mixture togive 2-ethoxy-1,4,6-androstatrien-3,17-dione (8. Compound 2 was also epoxidized withm-CPBA in dichloromethane to afford 6α,7α-epoxy-1,4-androstadien-3,17-dione (4,which was reacted with NaBH4 to synthesize 6α,7α-epoxy-4-androsten-3β,17β-diol (9.Compound 4 was reduced with Li metal in absolute ethanol-tetrahydrofuran mixture toform 7β-ethoxy-6α-hydroxy-1,4-androstadien-3,17-dione (10. Compound 2 was reducedwith NaBH4 in absolute ethanol to form 4,6-androstadien-3β,17β-diol (5, which wasreacted with 30% H2O2 to give the original compound, but which reacted with m-CPBAto give 4β,5β-epoxy-6-androsten-3β,17β-diol (6.

  1. Nuclear respiratory factor 1 overexpression attenuates anti-benzopyrene‑7,8-diol-9,10-epoxide-induced S-phase arrest of bronchial epithelial cells.

    Science.gov (United States)

    Wu, Jing; Wang, Yaning; Wo, Da; Zhang, Lijuan; Li, Jue

    2016-05-01

    Nuclear respiratory factor 1 (NRF-1) has important roles in the regulation of several key metabolic genes required for cellular growth and respiration. A previous study by our group indicated that NRF‑1 is involved in mitochondrial dysfunction induced by the environmental pollutant benzo[a]pyrene in the 16HBE human bronchial epithelial cell line. In the present study, it was observed that its genotoxic metabolite, anti‑benzopyrene‑7,8‑diol‑9,10‑epoxide (BPDE), triggered cell cycle arrest in S‑phase in 16HBE cells by activating ataxia-telangiectasia (ATM)/checkpoint kinase (Chk)2 and ATM and Rad3 related (ATR)/Chk1 signaling pathways. NRF‑1 expression was suppressed by BPDE after treatment for 6 h. Flow cytometric analysis revealed that NRF‑1 overexpression attenuated cell cycle arrest in S‑phase induced by BPDE. In line with this result, DNA‑damage checkpoints were activated following NRF‑1 overexpression, as demonstrated by increased phosphorylation of ATM, Chk2 and γH2AX, but not ATR and Chk1, according to western blot analysis. It was therefore indicated that NRF‑1 overexpression attenuated BPDE‑induced S‑phase arrest via the ATM/Chk2 signaling pathway. PMID:27035420

  2. Comparison of epoxide and free-radical mechanisms for activation of benzo[a]pyrene by Sprague-Dawley rat liver microsomes

    International Nuclear Information System (INIS)

    Coincubation of [6-3H]benzo[a]pyrene ([6-3H]BP) and [14C]BP with SD rat liver microsomes produced metabolic profiles that showed that the C-6 of BP was not affected by formation of 4,5-dihydro-4,5-dihydroxy-BP, 7,8-dihydro-7,8-dihydroxy-BP, and 9,10-dihydro-9,10-dihydroxy-BP nor the 3- and 9-phenols of BP. Complete retention of tritium at C-6, except in the three quinones, confirmed the radical-cation model for formation of the 6-oxo-radical followed by oxidation to quinone. Epoxide formation at the carcinogenically active regions of BP appeared to biochemically isolate from 6-position activation and suggested that the microsomal epoxide pathway is unrelated to the radicalcation scheme. These molar ratios derived from double-label experiments reinforced the current literature that indicates the epoxide mechanism as the major pathway toward carcinogenic forms of BP

  3. TPX2 in malignantly transformed human bronchial epithelial cells by anti-benzo[a]pyrene-7,8-diol-9,10-epoxide

    International Nuclear Information System (INIS)

    In order to elucidate the function of the targeting protein for Xenopus kinesin-like protein 2 (Xklp2) (TPX2) in the malignant transformation of human bronchial epithelial cells induced by anti-benzo[a]pyrene-trans-7, 8-dihydrodiol-9, 10-epoxide (anti-BPDE), TPX2 was characterized in cells at both the gene and the protein levels. TPX2 was present at higher levels in 16HBE-C cells than in 16HBE cells as demonstrated by two-dimensional gel electrophoresis, immunocytochemistry, Western blot analysis and RT-PCR. TPX2 was also detected in lung squamous-cell carcinoma tissues by immunohistochemistry, but not in normal lung tissues. Depression of TPX2 by RNA interference in 16HBE-C cells led to a decrease in cell proliferation, S-phase cell cycle arrest and cell apoptosis. Abnormal TPX2 tyrosine phosphorylation was detected in 16HBE-C cells, and this could be inhibited, to different degrees, by tyrosine kinase inhibitors. Inhibiting tyrosine phosphorylation in 16HBE-C cells by three selected tyrosine protein kinase inhibitors, tyrphostin 47, AG112 and AG555, caused G0/G1-phase cell cycle arrest. Our results suggest that anti-BPDE can cause the over-expression of TPX2 and its aberrant tyrosine phosphorylation. Misregulation of TPX2 affects the cell cycle state, proliferation rates and apoptosis

  4. Quantum chemical studies of epoxide-transforming enzymes

    OpenAIRE

    Hopmann, Kathrin H.

    2007-01-01

    Density functional theory is employed to study the reaction mechanisms of different epoxide-transforming enzymes. Calculations are based on quantum chemical active site models, which are build from X-ray crystal structures. The models are used to study conversion of various epoxides into their corresponding diols or substituted alcohols. Epoxide-transforming enzymes from three different families are studied. The human soluble epoxide hydrolase (sEH) belongs to the α/β-hydrolase fold family. s...

  5. Direct Copolymerization of CO2 and Diols

    Science.gov (United States)

    Tamura, Masazumi; Ito, Kazuki; Honda, Masayoshi; Nakagawa, Yoshinao; Sugimoto, Hiroshi; Tomishige, Keiichi

    2016-04-01

    Direct polymerization of CO2 and diols is promising as a simple and environmental-benign method in place of conventional processes using high-cost and/or hazardous reagents such as phosgene, carbon monoxide and epoxides, however, there are no reports on the direct method due to the inertness of CO2 and severe equilibrium limitation of the reaction. Herein, we firstly substantiate the direct copolymerization of CO2 and diols using CeO2 catalyst and 2-cyanopyridine promotor, providing the alternating cooligomers in high diol-based yield (up to 99%) and selectivity (up to >99%). This catalyst system is applicable to various diols including linear C4-C10 α,ω-diols to provide high yields of the corresponding cooligomers, which cannot be obtained by well-known methods such as copolymerization of CO2 and cyclic ethers and ring-opening polymerization of cyclic carbonates. This process provides us a facile synthesis method for versatile polycarbonates from various diols and CO2 owing to simplicity of diols modification.

  6. X-ray structure of potato epoxide hydrolase sheds light on substrate specificity in plant enzymes

    OpenAIRE

    Mowbray, Sherry L.; Elfström, Lisa T.; Ahlgren, Kerstin M; Andersson, C. Evalena; Widersten, Mikael

    2006-01-01

    Epoxide hydrolases catalyze the conversion of epoxides to diols. The known functions of such enzymes include detoxification of xenobiotics, drug metabolism, synthesis of signaling compounds, and intermediary metabolism. In plants, epoxide hydrolases are thought to participate in general defense systems. In the present study, we report the first structure of a plant epoxide hydrolase, one of the four homologous enzymes found in potato. The structure was solved by molecular replacement and refi...

  7. A predictive model for epoxide hydrolase-generated stereochemistry in the biosynthesis of 9-membered enediyne antitumor antibiotics

    OpenAIRE

    Horsman, Geoffrey P.; Lechner, Anna; Ohnishi, Yasuo; Moore, Bradley S.; Shen, Ben

    2013-01-01

    Nine-membered enediyne antitumor antibiotics C-1027, neocarzinostatin (NCS), and kedarcidin (KED) possess enediyne cores to which activity-modulating peripheral moieties are attached via (R)- or (S)-vicinal diols. We have previously shown that this stereochemical difference arises from hydrolysis of epoxide precursors by epoxide hydrolases (EHs) with different regioselectivities – the “inverting” EH, such as SgcF, hydrolyzes an (S)-epoxide substrate to yield an (R)-diol in C-1027 biosynthesis...

  8. Effect of heavy metals on the metabolism of benzo(a)pyrene in rats

    Energy Technology Data Exchange (ETDEWEB)

    Honey, S.A.; Yuan, Zhi-Xin; Kumar, S.; Sikka, H.C. [State Univ. of New York College, Buffalo, NY (United States)

    1996-12-31

    In order to investigate the interaction of heavy metals and PAHs, we have examined the effect of methylmercuric chloride and cadmium chloride on the oxidative metabolism by rats of benzo(a)pyrene [BaP], a model carcinogenic PAR Treatment of male rats with 2.5 or 5.0 mg/kg methylmercury (ip) reduced the rate of metabolism of BaP by liver microsomes by 38.7 and 62.2%, respectively. Cadmium was more potent than methylmercury, decreasing the rate of metabolism of BaP by 28.4, 52.2, and 69.7% by liver microsomes of rats treated with 0.5, 1.0, and 1.5 mg/kg of cadmium, respectively. The liver microsomes from animals treated with methylmercury or cadmium produced a greater proportion of BP-phenols and a lower portion of BP-diols than did the microsomes from untreated animals, suggesting that both metals also inhibit the activity of epoxide hydrase. Neither methylmercury nor cadmium had an effect on the proportion of BP-quinones formed by liver microsomes. Treatment of rats with methylmercury or cadmium did not inhibit the metabolism of BaP by liver microsomes from animals treated with 3-methylcholanthrene (3-MC) prior to metal administration, suggesting that 3-MC treatment protects against the effect of methylmercury or cadmium on the oxidative metabolism of BaP.

  9. Potent Urea and Carbamate Inhibitors of Soluble Epoxide Hydrolases

    Science.gov (United States)

    Morisseau, Christophe; Goodrow, Marvin H.; Dowdy, Deanna; Zheng, Jiang; Greene, Jessica F.; Sanborn, James R.; Hammock, Bruce D.

    1999-08-01

    The soluble epoxide hydrolase (sEH) plays a significant role in the biosynthesis of inflammation mediators as well as xenobiotic transformations. Herein, we report the discovery of substituted ureas and carbamates as potent inhibitors of sEH. Some of these selective, competitive tightbinding inhibitors with nanomolar Ki values interacted stoichiometrically with the homogenous recombinant murine and human sEHs. These inhibitors enhance cytotoxicity of trans-stilbene oxide, which is active as the epoxide, but reduce cytotoxicity of leukotoxin, which is activated by epoxide hydrolase to its toxic diol. They also reduce toxicity of leukotoxin in vivo in mice and prevent symptoms suggestive of acute respiratory distress syndrome. These potent inhibitors may be valuable tools for testing hypotheses of involvement of diol and epoxide lipids in chemical mediation in vitro or in vivo systems.

  10. Discovery and characterization of thermophilic limonene-1,2-epoxide hydrolases from hot spring metagenomic libraries

    DEFF Research Database (Denmark)

    Ferrandi, Erica Elisa; Sayer, Christopher; Isupov, Michail N.;

    2015-01-01

    The epoxide hydrolases (EHs) represent an attractive option for the synthesis of chiral epoxides and 1,2-diols which are valuable building blocks for the synthesis of several pharmaceutical compounds. A metagenomic approach has been used to identify two new members of the atypical EH limonene-1...

  11. Limonene-1,2-Epoxide Hydrolase from Rhodococcus erythropolis DCL14 Belongs to a Novel Class of Epoxide Hydrolases

    OpenAIRE

    van der Werf, Mariët J.; Overkamp, Karin M; de Bont, Jan A. M.

    1998-01-01

    An epoxide hydrolase from Rhodococcus erythropolis DCL14 catalyzes the hydrolysis of limonene-1,2-epoxide to limonene-1,2-diol. The enzyme is induced when R. erythropolis is grown on monoterpenes, reflecting its role in the limonene degradation pathway of this microorganism. Limonene-1,2-epoxide hydrolase was purified to homogeneity. It is a monomeric cytoplasmic enzyme of 17 kDa, and its N-terminal amino acid sequence was determined. No cofactor was required for activity of this colorless en...

  12. Metabolism and macromolecular binding of benzo(a)pyrene and its noncarcinogenic isomer benzo(e)pyrene in cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Selkirk, J.K.; MacLeod, M.C.

    1978-01-01

    The carcinogenicity of the polycyclic aromatic hydrocarbon benzo(a)pyrene (B(a)P) is thought to result from the metabolic formation of a highly reactive intermediate, 7,8-dihydrodiol-9,10-oxy-B(a)P which subsequently interacts with cellular macromolecules to produce neoplasia. Evidence has been presented implicating similar bay-region diol-epoxides as the ultimate carcinogenic forms of benz(a)anthracene, 7-methyl-benz(a)anthracene, dibenz(a,h)anthracene, and chrysene. Benzo(e)pyrene (B(e)P), on the other hand, is relatively inert when tested for carcinogenicity on mouse skin and rat trachea and when tested for mutagenicity in a mammalian system. This B(e)P molecule contains two (equivalent) bay regions and quantum mechanical model calculations suggest that 9,10-dihydrodiol-11,12-oxy-B(e)P can easily form a reactive bay-region-adjacent carbonium ion. In order to explain the noncarcinogenicity of B(e)P in the context of the bay region theory, we have studied the metabolism of B(e)P by rat liver microsomes and by cultured hamster embryo fibroblasts. In both systems, the major metabolic pathways involve the K-region of B(e)P, with little or no attack on the isolated benzo ring. These results suggest that the lack of carcinogenicity of B(e)P may reflect its preferred mode of interaction with the cellular metabolic machinery.

  13. An asymmetric route to 2,3-epoxy-syn-1,4-cyclohexane diol derivatives using ring closing metathesis (RCM)

    Indian Academy of Sciences (India)

    Soumitra Maity; Subrata Ghosh

    2010-11-01

    An asymmetric route for the synthesis of highly functionalized 2,3-epoxy-syn-1,4-cyclohexane diol derivatives present in some polyketide natural products has been developed. The key step involves RCM of an appropriately constructed 1,7-dienol derived from D-mannitol to cyclohexane-1,4-diol followed by its stereoselective epoxidation.

  14. Specificity in interaction of benzo[a]pyrene with nuclear macromolecules: implication of derivatives of two dihydrodiols in protein binding

    International Nuclear Information System (INIS)

    Benzo[a]pyrene (B[a]P), 7,8-dihydroxy-7,8-dihydro-B[a]P, and 9,10-dihydroxy-9,10-dihydro-B[a]P are metabolized by hamster embryo cells to derivatives that bind to nuclear macromolecules. The selectivity for different classes of macromolecules varies depending on the compound analyzed. The ratio of DNA specific activity to protein specific activity (pmol bound/mg of macromolecules) is high (1.51) for 7,8-dihydroxy-7,8-dihydro-B[a]P, extremely low (0.03) for 9,10-dihydroxy-9,10-dihydro-B[a]P, and intermediate (0.26) for B[a]P. Histones H3 and H2A are the major targets of 7,8-dihydroxy-7,8-dihydro-B[a]P; a protein(s) with a mobility similar to that of histone H1 is heavily labeled by 9,10 dihydroxy-9,10-dihydro-B[a]P, with minor labeling of other (nonhistone) bands. The labeling pattern seen with B[a]P is a combination of the patterns seen with the two dihydrodiol metabolites studied. Analysis of the ethyl acetate-soluble metabolites suggests that hamster embryo cells produce 9,10-dihydroxy-7,8-oxy-7,8,9,10-tetrahydro-B[a]P from 9,10-dihydroxy-9,10-dihydro-B[a]P and raise the possibility that this vicinal diol epoxide is an intermediate in the binding of 9,10-dihydroxy-9,10-dihydro-B[a]P to nuclear proteins. The differences seen suggest that factors other than the intrinsic chemical reactivity of the epoxide group are extremely important in the ineraction of potential ultimate carcinogens with biological systems

  15. Data set of optimal parameters for colorimetric red assay of epoxide hydrolase activity.

    Science.gov (United States)

    de Oliveira, Gabriel Stephani; Adriani, Patricia Pereira; Borges, Flavia Garcia; Lopes, Adriana Rios; Campana, Patricia T; Chambergo, Felipe S

    2016-09-01

    The data presented in this article are related to the research article entitled "Epoxide hydrolase of Trichoderma reesei: Biochemical properties and conformational characterization" [1]. Epoxide hydrolases (EHs) are enzymes that catalyze the hydrolysis of epoxides to the corresponding vicinal diols. This article describes the optimal parameters for the colorimetric red assay to determine the enzymatic activity, with an emphasis on the characterization of the kinetic parameters, pH optimum and thermal stability of this enzyme. The effects of reagents that are not resistant to oxidation by sodium periodate on the reactions can generate false positives and interfere with the final results of the red assay. PMID:27366781

  16. Tumor initiating and promoting activities of various benzo(a)pyrene metabolites in mouse skin

    Energy Technology Data Exchange (ETDEWEB)

    Slaga, T J; Bracken, W M; Viaje, A; Berry, D L; Fischer, S M; Miller, D R; Levin, W; Conney, A H; Yagi, H; Jerina, D M

    1977-01-01

    The skin tumor-initiating activities of the twelve isomeric phenols of BP revealed that 2-OHBP was as potent as BP while 11-OHBP was moderately active and the others were weak or inactive. However, 2-OHBP has not been shown to be formed from BP in the skin or any other tissue. The (-)-trans-7,8-diol of BP skin was found to be more active as a skin tumor initiator than BP suggesting that it is a proximal carcinogen. The data on carcinogenicity, mutagenicity and metabolism suggest that BP-7..beta.., 8..cap alpha..-diol-9..cap alpha.., 10..cap alpha..-epoxide is the ultimate carcinogenic form of BP. The skin tumor-initiating activities of the various BP metabolites correlate very well with their complete carcinogenic in mouse skin except for BP-7..beta.., 8..cap alpha..-diol-9..cap alpha.., 10..cap alpha..-epoxide. It was found to have skin tumor initiating activity but not complete carcinogenic activity. However, BP-7..beta.., 8..cap alpha..-diol-9..cap alpha.., 10..cap alpha..-epoxide was found to be a very potent complete carcinogen in newborn mice. It is possible that BP-7..beta.., 8..cap alpha..-diol-9..cap alpha.., 10..cap alpha..-epoxide is only a tumor initiator in which a promoting stimulus must be supplied for carcinogenic activity. A natural tumor promoting stimulus may be present in the newborn mouse. There is also a good correlation between the skin tumor initiating activities of the various BP metabolites and their mutagenic activity in the V79 mammalian cell mediated mutagenesis system.

  17. Access to enantiopure aromatic epoxides and diols using epoxide hzdrolases derived from total biofilter DNA

    Czech Academy of Sciences Publication Activity Database

    Kotík, Michael; Štěpánek, Václav; Grulich, Michal; Kyslík, Pavel; Archelas, A.

    2010-01-01

    Roč. 65, 1-4 (2010), s. 41-48. ISSN 1381-1177 R&D Projects: GA ČR GA204/06/0458 Institutional research plan: CEZ:AV0Z50200510 Keywords : Chiral resolution * Enantioconvergent reaction * Enantioselectivity Subject RIV: CE - Biochemistry Impact factor: 2.330, year: 2010

  18. Influence of cell cycle on responses of MCF-7 cells to benzo[a]pyrene

    Directory of Open Access Journals (Sweden)

    Giddings Ian

    2011-06-01

    Full Text Available Abstract Background Benzo[a]pyrene (BaP is a widespread environmental genotoxic carcinogen that damages DNA by forming adducts. This damage along with activation of the aryl hydrocarbon receptor (AHR induces complex transcriptional responses in cells. To investigate whether human cells are more susceptible to BaP in a particular phase of the cell cycle, synchronised breast carcinoma MCF-7 cells were exposed to BaP. Cell cycle progression was analysed by flow cytometry, DNA adduct formation was assessed by 32P-postlabeling analysis, microarrays of 44K human genome-wide oligos and RT-PCR were used to detect gene expression (mRNA changes and Western blotting was performed to determine the expression of some proteins, including cytochrome P450 (CYP 1A1 and CYP1B1, which are involved in BaP metabolism. Results Following BaP exposure, cells evaded G1 arrest and accumulated in S-phase. Higher levels of DNA damage occurred in S- and G2/M- compared with G0/G1-enriched cultures. Genes that were found to have altered expression included those involved in xenobiotic metabolism, apoptosis, cell cycle regulation and DNA repair. Gene ontology and pathway analysis showed the involvement of various signalling pathways in response to BaP exposure, such as the Catenin/Wnt pathway in G1, the ERK pathway in G1 and S, the Nrf2 pathway in S and G2/M and the Akt pathway in G2/M. An important finding was that higher levels of DNA damage in S- and G2/M-enriched cultures correlated with higher levels of CYP1A1 and CYP1B1 mRNA and proteins. Moreover, exposure of synchronised MCF-7 cells to BaP-7,8-diol-9,10-epoxide (BPDE, the ultimate carcinogenic metabolite of BaP, did not result in significant changes in DNA adduct levels at different phases of the cell cycle. Conclusions This study characterised the complex gene response to BaP in MCF-7 cells and revealed a strong correlation between the varying efficiency of BaP metabolism and DNA damage in different phases of the cell

  19. Epoxidation catalyst and process

    Science.gov (United States)

    Linic, Suljo; Christopher, Phillip

    2010-10-26

    Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

  20. Succinic anhydrides from epoxides

    Energy Technology Data Exchange (ETDEWEB)

    Coates, Geoffrey W.; Rowley, John M.

    2013-07-09

    Catalysts and methods for the double carbonylation of epoxides are disclosed. Each epoxide molecule reacts with two molecules of carbon monoxide to produce a succinic anhydride. The reaction is facilitated by catalysts combining a Lewis acidic species with a transition metal carbonyl complex. The double carbonylation is achieved in single process by using reaction conditions under which both carbonylation reactions occur without the necessity of isolating or purifying the product of the first carbonylation.

  1. Succinic anhydrides from epoxides

    Energy Technology Data Exchange (ETDEWEB)

    Coates, Geoffrey W; Rowley, John M

    2014-12-30

    Catalysts and methods for the double carbonylation of epoxides are disclosed. Each epoxide molecule reacts with two molecules of carbon monoxide to produce a succinic anhydride. The reaction is facilitated by catalysts combining a Lewis acidic species with a transition metal carbonyl complex. The double carbonylation is achieved in single process by using reaction conditions under which both carbonylation reactions occur without the necessity of isolating or purifying the product of the first carbonylation.

  2. Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

    Directory of Open Access Journals (Sweden)

    Meriem K. Abderrezak

    2015-10-01

    Full Text Available The cross metathesis of 1,2-epoxy-5-hexene (1 with methyl acrylate and acrylonitrile was investigated as an entry to the synthesis of polyfunctional compounds. The resulting cross metathesis products were hydrogenated in a tandem fashion employing the residual ruthenium from the metathesis step as the hydrogenation catalyst. Interestingly, the epoxide ring remained unreactive toward this hydrogenation method. The saturated compound resulting from the cross metathesis of 1 with methyl acrylate was transformed by means of nucleophilic ring-opening of the epoxide to furnish a diol, an alkoxy alcohol and an amino alcohol in high yields.

  3. One step synthesis of 6-oxo-cholestan-3β,5α-diol

    Energy Technology Data Exchange (ETDEWEB)

    Voisin, Maud; Silvente-Poirot, Sandrine; Poirot, Marc, E-mail: marc.poirot@inserm.fr

    2014-04-11

    Highlights: • Cholesterol-5,6-epoxides are metabolized into cholestane-3β,5α,6β-triol (CT) in cancer cells. • 6-Oxo-cholestan-3β,5α-diol (OCDO) is a putative metabolite of CT. • The one step syntheses of CT and OCDO from cholesterol are reported. • The one step syntheses of labelled CT and OCDO are reported. - Abstract: Cholesterol metabolism has been recently linked to cancer, highlighting the importance of the characterization of new metabolic pathways in the sterol series. One of these pathways is centered on cholesterol-5,6-epoxides (5,6-ECs). 5,6-ECs can either generate dendrogenin A, a tumor suppressor present in healthy mammalian tissues, or the carcinogenic cholestane-3β,5α,6β-triol (CT) and its putative metabolite 6-oxo-cholestan-3β,5α-diol (OCDO) in tumor cells. We are currently investigating the identification of the enzyme involved in OCDO biosynthesis, which would be highly facilitated by the use of commercially unavailable [{sup 14}C]-cholestane-3β,5α,6β-triol and [{sup 14}C]-6-oxo-cholestan-3β,5α-diol. In the present study we report the one-step synthesis of [{sup 14}C]-cholestane-3β,5α,6β-triol and [{sup 14}C]-6-oxo-cholestan-3β,5α-diol by oxidation of [{sup 14}C]-cholesterol with iodide metaperiodate (HIO{sub 4})

  4. Benzo[a]pyrene and glycine N-methyltransferse Interactions: Gene expression profiles of the liver detoxification pathway

    International Nuclear Information System (INIS)

    Benzo[a]pyrene (BaP) is one of many polycyclic aromatic hydrocarbons that have been identified as major risk factors for developing various cancers. We previously demonstrated that the liver cancer susceptibility gene glycine N-methyltransferase (GNMT) is capable of binding with BaP and protecting cells from BaP-7,8-diol 9,10-epoxide-DNA adduct formation. In this study, we used a cytotoxicity assay to demonstrate that the higher expression level of GNMT, the lower cytotoxicity occurred in the cells treated with BaP. In addition, a cDNA microarray containing 7,597 human genes was used to examine gene expression patterns in BaP-treated HepG2 (a liver cancer cell line that expresses very low levels of GNMT) and SCG2-1-1 (a stable HepG2 clone that expresses high levels of GNMT) cells. The results showed that among 6,018 readable HepG2 genes, 359 (6.0%) were up-regulated more than 1.5-fold and 768 (12.8%) were down-regulated. Overexpression of GNMT in SCG2-1-1 cells resulted in the down-regulation of genes related to the detoxification, kinase/phosphatase pathways, and oncogenes. Furthermore, real-time PCR was used to validate microarray data from 21 genes belonging to the detoxification pathway. Combining both microarray and real-time PCR data, the results showed that among 89 detoxification pathway genes analyzed, 22 (24.7%) were up-regulated and 6 (6.7%) were down-regulated in BaP-treated HepG2 cells, while in the BaP-treated SCG2-1-1 cells, 12 (13.5%) were up-regulated and 26 (29.2%) were down-regulated (P < 0.001). Therefore, GNMT sequesters BaP, diminishes BaP's effects to the liver detoxification pathway and prevents subsequent cytotoxicity

  5. Secondary deuterium isotope effects on epoxide methanolysis reactions

    International Nuclear Information System (INIS)

    Secondary kinetic deuterium isotope effects have recently come into widespread use as probes of reaction mechanism and transition state structure. Isotopic substitution at the reacting carbon gives rise to the so-called α effect due to differences in the energetics of out-of-plane bending of C-H and C-D bonds; these effects are usually interpreted in terms of changes in hybridization at the reacting carbon as the reaction processes. Alternately isotopic substitution at carbons adjacent to the reacting carbon leads to a β effect presumably arising from differences in the ability of C-H and C-D bands to interact with orbitals on the reacting carbon by means of hyperconjugation. In connection with mechanistic studies of the epoxide-diol pathway secondary deuterium isotope effects were used to compare epoxidation of olefins by cytochrome P-450 with olefin epoxidation by m-chloroperbenzoic acid. Observations of secondary deuterium isotope effects on the acid-and base-catalyzed methanolysis of p-nitrostyrene oxide, a chemical model system for the epoxide hydrase system were reported. This is the first observation of an α effect at the β carbon or a secondary effect at a neighboring carbon not attributable to hyperconjugation phenomena. Such effects might be expected but are not observed in the solvolysis of β-arglethyl tosylates and in the thermal cic-trans isomerization of cyclopropane derivatives. Another interesting result is the parallelism that the major reactions in acid and base both involve late or product-like transition states, while both minor reactions involve early or reactant-like transition states. These studies have shown that secondary deuterium isotope effects provide a sensitive and predictable probe for mechanistic studies of epoxide reactions. 3 tables

  6. Rapid synthesis of macrocycles from diol precursors

    DEFF Research Database (Denmark)

    Wingstrand, Magnus; Madsen, Charlotte Marie; Clausen, Mads Hartvig

    2009-01-01

    A method for the formation of synthetic macrocycles with different ring sizes from diols is presented. Reacting a simple diol precursor with electrophilic reagents leads to a cyclic carbonate, sulfite or phosphate in a single step in 25-60% yield. Converting the cyclization precursor to a bis...

  7. An epoxide modified polymerisable compound

    International Nuclear Information System (INIS)

    The description is given of an epoxide modified polymerisable compound. It includes a mixture of the following reactive substances; a vinyled carboxylic acid which is acrylic or methacrylic acid; an aliphatic epoxide; a diepoxide and a modifier containing a reagent group that is a carboxylic acid; a phenol, an alcohol, a carboxylic acid amide or a carboxylic acid halogenide

  8. Predictive model for epoxide hydrolase-generated stereochemistry in the biosynthesis of nine-membered enediyne antitumor antibiotics.

    Science.gov (United States)

    Horsman, Geoffrey P; Lechner, Anna; Ohnishi, Yasuo; Moore, Bradley S; Shen, Ben

    2013-08-01

    Nine-membered enediyne antitumor antibiotics C-1027, neocarzinostatin (NCS), and kedarcidin (KED) possess enediyne cores to which activity-modulating peripheral moieties are attached via (R)- or (S)-vicinal diols. We have previously shown that this stereochemical difference arises from hydrolysis of epoxide precursors by epoxide hydrolases (EHs) with different regioselectivities. The inverting EHs, such as SgcF, hydrolyze an (S)-epoxide substrate to yield an (R)-diol in C-1027 biosynthesis, whereas the retaining EHs, such as NcsF2 and KedF, hydrolyze an (S)-epoxide substrate to yield an (S)-diol in NCS and KED biosynthesis. We now report the characterization of a series of EH mutants and provide a predictive model for EH regioselectivity in the biosynthesis of the nine-membered enediyne antitumor antibiotics. A W236Y mutation in SgcF increased the retaining activity toward (S)-styrene oxide by 3-fold, and a W236Y/Q237M double mutation in SgcF, mimicking NcsF2 and KedF, resulted in a 20-fold increase in the retaining activity. To test the predictive utility of these mutations, two putative enediyne biosynthesis-associated EHs were identified by genome mining and confirmed as inverting enzymes, SpoF from Salinospora tropica CNB-440 and SgrF (SGR_625) from Streptomyces griseus IFO 13350. Finally, phylogenetic analysis of EHs revealed a familial classification according to inverting versus retaining activity. Taken together, these results provide a predictive model for vicinal diol stereochemistry in enediyne biosynthesis and set the stage for further elucidating the origins of EH regioselectivity. PMID:23844627

  9. A predictive model for epoxide hydrolase-generated stereochemistry in the biosynthesis of 9-membered enediyne antitumor antibiotics

    Science.gov (United States)

    Horsman, Geoffrey P.; Lechner, Anna; Ohnishi, Yasuo; Moore, Bradley S.; Shen, Ben

    2013-01-01

    Nine-membered enediyne antitumor antibiotics C-1027, neocarzinostatin (NCS), and kedarcidin (KED) possess enediyne cores to which activity-modulating peripheral moieties are attached via (R)- or (S)-vicinal diols. We have previously shown that this stereochemical difference arises from hydrolysis of epoxide precursors by epoxide hydrolases (EHs) with different regioselectivities – the “inverting” EH, such as SgcF, hydrolyzes an (S)-epoxide substrate to yield an (R)-diol in C-1027 biosynthesis, while the “retaining” EHs, such as NcsF2 and KedF, hydrolyze an (S)-epoxide substrate to yield an (S)-diol in NCS and KED biosynthesis. We now report the characterization of a series of EH mutants and provide a predictive model for EH regioselectivity in the biosynthesis of the 9-membered enediyne antitumor antibiotics. A W236Y mutation in SgcF increased the retaining activity towards (S)-styrene oxide 3-fold, and a W236Y/Q237M double mutation in SgcF, mimicking NcsF2 and KedF, resulted in a 20-fold increase in the retaining activity. To test the predictive utility of these mutations, two putative enediyne biosynthesis-associated EHs were identified by genome mining and confirmed as inverting enzymes – SpoF from Salinospora tropica CNB-440 and SgrF (SGR_625) from Streptomyces griseus IFO 13350. Finally, phylogenetic analysis of EHs revealed a familial classification according to inverting versus retaining activity. Taken together, these results provide a predictive model for the vicinal diol stereochemistry in enediyne biosynthesis and set the stage for further elucidating the origins of EH regioselectivity. PMID:23844627

  10. Uptake of 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene in melanin-containing tissues

    Energy Technology Data Exchange (ETDEWEB)

    Roberto, A.; Larsson, B.S. [Uppsala Univ., Dept. of Pharmaceutical Biosciences, Div. of Toxicology, Uppsala (Sweden); Tjaelve, H. [The Swedish Univ. of Agricultural Sciences, Dept. of Pharmacology and Toxicology, Uppsala (Sweden)

    1996-08-01

    It is widely accepted that UV exposure is the main etiological factor for malignant melanoma. Epidemiologic studies, however, have indicated that also chemical carcinogens may be a risk factor for the disease. Polycyclic aromatic hydrocarbons such as 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene represent an important class of carcinogenic chemicals. It is known that 7,12-dimethylbenz(a)anthracene can induce melanotic tumours in various animal species, and human melanocytes in culture have been found to be capable of metabolizing benzo(a)pyrene to its proximate carcinogen benzo(a)pyrene-7,8-diol. In the present study the disposition of {sup 14}C- and {sup 3}H-7,12-dimethylbenz(a)anthracene and {sup 14}C-benzo(a)pyrene was studied in pigmented and albino mice and Syrian golden hamsters by whole-body autoradiography. The results showed pronounced retention of label in the melanin-containing structures of the eyes and the hair follicles in the pigmented animals. The labelling of the corresponding structures in the albino animals was low. Additional experiments showed that 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene as well as some of their metabolites are bound to melanin in vitro. The specific localization of the polycyclic aromatic hydrocarbons in pigmented tissues due to melanin affinity, combined with bioactivating capacity of melanocytes, suggest that these substances may play a role in the induction of malignant melanoma. (au).

  11. Dysregulation of soluble epoxide hydrolase and lipidomic profiles in anorexia nervosa.

    Science.gov (United States)

    Shih, P B; Yang, J; Morisseau, C; German, J B; Zeeland, A A Scott-Van; Armando, A M; Quehenberger, O; Bergen, A W; Magistretti, P; Berrettini, W; Halmi, K A; Schork, N; Hammock, B D; Kaye, W

    2016-04-01

    Individuals with anorexia nervosa (AN) restrict eating and become emaciated. They tend to have an aversion to foods rich in fat. Because epoxide hydrolase 2 (EPHX2) was identified as a novel AN susceptibility gene, and because its protein product, soluble epoxide hydrolase (sEH), converts bioactive epoxides of polyunsaturated fatty acid (PUFA) to the corresponding diols, lipidomic and metabolomic targets of EPHX2 were assessed to evaluate the biological functions of EPHX2 and their role in AN. Epoxide substrates of sEH and associated oxylipins were measured in ill AN, recovered AN and gender- and race-matched controls. PUFA and oxylipin markers were tested as potential biomarkers for AN. Oxylipin ratios were calculated as proxy markers of in vivo sEH activity. Several free- and total PUFAs were associated with AN diagnosis and with AN recovery. AN displayed elevated n-3 PUFAs and may differ from controls in PUFA elongation and desaturation processes. Cytochrome P450 pathway oxylipins from arachidonic acid, linoleic acid, alpha-linolenic acid and docosahexaenoic acid PUFAs are associated with AN diagnosis. The diol:epoxide ratios suggest the sEH activity is higher in AN compared with controls. Multivariate analysis illustrates normalization of lipidomic profiles in recovered ANs. EPHX2 influences AN risk through in vivo interaction with dietary PUFAs. PUFA composition and concentrations as well as sEH activity may contribute to the pathogenesis and prognosis of AN. Our data support the involvement of EPHX2-associated lipidomic and oxylipin dysregulations in AN, and reveal their potential as biomarkers to assess responsiveness to future intervention or treatment. PMID:25824304

  12. Detoxification Strategy of Epoxide Hydrolase

    OpenAIRE

    Arand, Michael; Cronin, Annette; Hengstler, Jan G.; Herrero Plana, Maria Elena; Lohmann, Matthias; Oesch, Franz

    2003-01-01

    The human microsomal epoxide hydrolase, a single enzyme, has to detoxify a broad range of structurally diverse, potentially genotoxic epoxides that are formed in the course of xenobiotic metabolism. The enzyme has developed a unique strategy to combine a broad substrate specificity with a high detoxification efficacy, by immediately trapping the reactive compounds as covalent intermediates and by being expressed at high levels for high trapping capacity. Computer simulation and experimental d...

  13. Epoxide hydrolase of Trichoderma reesei: Biochemical properties and conformational characterization.

    Science.gov (United States)

    de Oliveira, Gabriel Stephani; Adriani, Patricia Pereira; Borges, Flavia Garcia; Lopes, Adriana Rios; Campana, Patricia T; Chambergo, Felipe S

    2016-08-01

    Epoxide hydrolases (EHs) are enzymes that are present in all living organisms and catalyze the hydrolysis of epoxides to the corresponding vicinal diols. EHs have biotechnological potential in chiral chemistry. We report the cloning, purification, enzymatic activity, and conformational analysis of the TrEH gene from Trichoderma reesei strain QM9414 using circular dichroism spectroscopy. The EH gene has an open reading frame encoding a protein of 343 amino acid residues, resulting in a molecular mass of 38.2kDa. The enzyme presents an optimum pH of 7.2, and it is highly active at temperatures ranging from 23 to 50°C and thermally inactivated at 70°C (t1/2=7.4min). The Michaelis constants (Km) were 4.6mM for racemic substrate, 21.7mM for (R)-(+)-styrene oxide and 3.0mM for (S)-(-)-styrene oxide. The kcat/Km analysis indicated that TrEH is enantioselective and preferentially hydrolyzes (S)-(-)-styrene oxide. The conformational stability studies suggested that, despite the extreme conditions (high temperatures and extremely acid and basic pHs), TrEH is able to maintain a considerable part of its regular structures, including the preservation of the native cores in some cases. The recombinant protein showed enantioselectivity that was distinct from other fungus EHs, making this protein a potential biotechnological tool. PMID:27177457

  14. Evaluation of adjuvants for a candidate conjugate vaccine against benzo[a]pyrene.

    Science.gov (United States)

    Schellenberger, Mario T; Farinelle, Sophie; Willième, Stéphanie; Muller, Claude P

    2011-01-01

    We have recently developed an experimental vaccine based on benzo[a]pyrene (B[a]P) conjugated to tetanus toxoid as a carrier protein. In combination with Freund adjuvant, this vaccine induces high levels of B[a]P-specific antibodies to protect against detrimental effects of this carcinogen. Here we evaluate this conjugate vaccine by replacing Freund adjuvant by adjuvants that are potentially compatible with their use in humans. We showed that all adjuvants tested induced specific antibodies against B[a]P and 7,8-diol-B[a]P, its carcinogenic metabolite. The best antibody levels were obtained with Quil A, MF-59 and Alum. Biological activity in terms of enhanced retention of B[a]P was confirmed in mice immunised with Quil A, Montanide, Alum and MF-59. Our findings demonstrate that a vaccination against B[a]P is feasible in combination with adjuvants licensed in humans. PMID:21245662

  15. Bifunctional Nb/Ti-MCM-41 catalyst in oxidative acidic reaction of cyclohexene to diol

    International Nuclear Information System (INIS)

    Bifunctional oxidative and acidic catalyst was prepared by incorporating titanium ion (Ti4+) and niobic acid in meso porous molecular sieves MCM-41 structure. The catalyst is active both in oxidation, and acid-catalyzed reaction of olefin to diol. Nb/ Ti-MCM-41 catalyst was prepared by first synthesizing Ti-MCM-41 by hydrothermal method, followed by subsequent impregnation of niobic acid (Nb) into Ti-MCM-41 at various % wt Nb loading. The framework structure of Ti-MCM-41 collapsed after incorporation of Nb but the tetrahedral form of Ti4+ still maintained with octahedral Nb species. Both Bronsted and Lewis acid sites are present in all Nb/ Ti-MCM-41 samples. The formation of cyclohexanediol in the epoxidation of cyclohexene proved the bifunctional oxidative and acidic catalyst through the formation of cyclohexane oxide. The yield increased with the increase amount of the Bronsted acid sites provided by niobium species. (author)

  16. Epoxide compounds. III. Synthesis of amino-β-diols and their PMR spectra

    International Nuclear Information System (INIS)

    The reactions of 2,2,3-trimethyl-5,6-epoxy-3-hexanol with ammonia and primary and secondary amines was studied. A comprehensive NMR spectral analysis was performed and extensive data on spin-spin coupling constants, chemical shift, and line structure are given. Yields and boiling points of the reaction products are tabulated

  17. Heterogeneously catalyzed reactions with vegetable oils : epoxidation and nucleophilic epoxide ring-opening with alcohols

    OpenAIRE

    Rios, Luis Alberto

    2003-01-01

    Chemical modification of vegetable oils, via epoxidation and epoxide ring-opening with alcohols was studied, using environmentally acceptable methods. Epoxidation of vegetable oils with peracids produced in the presence of heterogeneous acidic catalysts requires low contact between the epoxide and the acidic centers to avoid consecutive reactions. The main by-product is the ketone, obtained from the epoxide rearrangement reaction. Ketone formation is favored by strongly acidic catalysts and b...

  18. Mutagenicity of algal metabolites of benzo(a)pyrene for Salmonella typhimurium

    International Nuclear Information System (INIS)

    The metabolism and growth effects of benzo(a)pyrene (BaP) were studied using a freshwater green alga, Selenastrum capricornutum. Algal cultures were incubated under gold light with BaP added at concentrations of 40, 160, 400, and 1200 μg/liter for the periods of 1-4 days. The metabolites and BaP were identified and quantified from ethyl acetate extracts of both algal cells and incubation medium. The ethyl acetate extracts were evaluated for genotoxicity using a micro-volume Salmonella typhimurium forward mutation assay with resistance to 8-azaguanine for selection. This assay detected the presence of small quantities of BaP and was particularly sensitive to the mutagenicity of BaP diols. Of those extracts prepared from algae and medium from cultures exposed to 400 μg BaP/liter (10 μg/25 ml culture), only algal cell extracts from one day's growth were mutagenic. In cultures exposed to 1200 μg BaP/liter (30 μg/25 ml culture), mutagenic materials were produced or persisted in both algae and media throughout the 4-day incubation. The observed mutagenic response can be attributed in part to the presence of unmetabolized BaP or to BaP diols

  19. Induction and inhibition of benzo(a)pyrene metabolism in human epidermal keratinocytes and dermal fibroblasts

    International Nuclear Information System (INIS)

    The effects of different growth conditions and various cytochrome P-450 inducers and inhibitors were examined on the benzo(a)pyrene (BP) metabolism of human skin cells in vitro. First, three different populations of neonatal foreskin fibroblasts were treated with 0.98 μM [G-3H]-BP at 9.6 Ci/mmole for 24 hours and the organic-extractable metabolites in the extracellular, the cytoplasmic, and the nuclear fractions were analyzed by high-pressure liquid chromatography (HPLC). Confluent cultures (contact-inhibited cells), which were nontransformable, metabolized BP to a much greater extent than the transformable populations, randomly-proliferating cultures (cells in logarithmic growth) and synchronized cultures (cells treated in S phase). The major extracellular BP metabolites detected were the 9,10-diol, the 7,8-diol, and the phenols, including all four tetrols observed only in the confluent cells. From this data, the state of confluency (i.e. the model for the in vivo state of skin cells) induced enzymes which catalyze primarily the detoxification pathways leading to the formation of metabolites which are readily excreted whereas cells which are actively dividing or synchronized induced the formation of metabolites from activation pathways that led to transformation. Next, the effects of four inducers (3-methylcholanthrene (3-MCA), phenobarbital (PB), isosafrole, and Arochlor 1254) and an inhibitor (butylated hydroxyanisole (BHA)) on the BP metabolism of human epidermal keratinocytes were evaluated

  20. Chromium Salen Mediated Alkene Epoxidation

    DEFF Research Database (Denmark)

    Petersen, Kaare Brandt; Norrby, Per-Ola; Daly, Adrian M.; Gilheany, Declan G.

    2002-01-01

    The mechanism of alkene epoxidation by chromium(v) oxo salen complexes has been studied by DFT and experimental methods. The reaction is compared to the closely related Mn-catalyzed process in an attempt to understand the dramatic difference in selectivity between the two systems. Overall, the......-spin surface. The low-spin addition of metal oxo species to an alkene leads to an intermediate which forms epoxide either with a barrier on the low-spin surface or without a barrier after spin inversion. Supporting evidence for this intermediate was obtained by using vinylcyclopropane traps. The chromium...

  1. Cytochrome b(5) and epoxide hydrolase contribute to benzo[a]pyrene-DNA adduct formation catalyzed by cytochrome P450 1A1 under low NADPH:P450 oxidoreductase conditions

    Czech Academy of Sciences Publication Activity Database

    Stiborová, M.; Moserová, M.; Černá, V.; Indra, R.; Dračínský, Martin; Šulc, M.; Henderson, C. J.; Wolf, C. R.; Schmeiser, H. H.; Phillips, D. H.; Frei, E.; Arlt, V. M.

    2014-01-01

    Roč. 318, Apr 6 (2014), s. 1-12. ISSN 0300-483X Grant ostatní: GA ČR(CZ) GAP301/10/0356 Institutional support: RVO:61388963 Keywords : benzo[a]pyrene * cytochrome P450 1A1 * NADPH:cytochrome P450 oxidoreductase * epoxide hydrolase * cytochrome b(5) Subject RIV: CC - Organic Chemistry Impact factor: 3.621, year: 2014

  2. Rhenium-Catalyzed Deoxydehydration of Diols and Polyols

    DEFF Research Database (Denmark)

    Dethlefsen, Johannes Rytter; Fristrup, Peter

    2015-01-01

    heniumcatalyzeddeoxydehydration (DODH) of a vicinal diol into analkene; this is a model system for abundant polyols like glyceroland sugar alcohols. The present contribution includesa review of early investigations of stoichiometric reactions involvingrhenium, diols, and alkenes followed by a discussion ofthe various catalytic...... systems that have been developed withemphasis on the nature of the reductant, the substrate scope,and mechanistic investigations....

  3. Synthesis and complexation characteristics of phenanthroline and bipyridine diols

    NARCIS (Netherlands)

    Koning, B.; Boer, J.W. de; Meetsma, A.; Kellogg, R.M.

    2004-01-01

    Neocuproine (2,9-dimethyl-1,10-phenanthroline) 1 was converted to achiral and chiral tetradentate phenanthroline diols 3a-c by addition to benzophenone, adamantanone and camphor, respectively. Analogously 6,6'-dimethyl-2,2'-bipyridine 2 was converted to diol 7a on base-induced addition to benzopheno

  4. Soluble epoxide hydrolase: A potential target for metabolic diseases.

    Science.gov (United States)

    He, Jinlong; Wang, Chunjiong; Zhu, Yi; Ai, Ding

    2016-05-01

    Epoxyeicosatrienoic acids (EETs), important lipid mediators derived from arachidonic acid, have many beneficial effects in metabolic diseases, including atherosclerosis, hypertension, cardiac hypertrophy, diabetes, non-alcoholic fatty liver disease, and kidney disease. Epoxyeicosatrienoic acids can be further hydrolyzed to less active diols by the enzyme soluble epoxide hydrolase (sEH). Increasing evidence suggests that inhibition of sEH increases levels of EETs, which have anti-inflammatory effects and can prevent the development of hypertension, atherosclerosis, heart failure, fatty liver, and multiple organ fibrosis. Arachidonic acid is the most abundant omega-6 polyunsaturated fatty acid (PUFA) and shares the same set of enzymes with omega-3 PUFAs, such as docosahexaenoic acid and eicosapentaenoic acid. The omega-3 PUFAs and metabolites, such as regioisomeric epoxyeicosatetraenoic acids and epoxydocosapentaenoic acids, have been reported to have strong vasodilatory and anti-inflammatory effects. Therefore, sEH may be a potential therapeutic target for metabolic disorders. In this review, we focus on our and other recent studies of the functions of sEH, including the effects of its eicosanoid products from both omega-3 and omega-6 PUFAs, in various metabolic diseases. We also discuss the possible cellular and molecular mechanisms underlying the regulation of sEH. PMID:26621325

  5. Practical radiochromatographic assay for cholesterol epoxide hydrase

    International Nuclear Information System (INIS)

    A method for the assay of cholesterol epoxide hydrase activity is described. The assay involves the thin-layer chromatographic separation and quantitation of radiolabeled cholestan-3β,5α,6α-epoxide and its major hydration product, cholestan-3β,5α,6β-triol. Radiochromatographic scanning is employed to quantitate the reaction. The procedure is sensitive, rapid, and nondestructive

  6. Cloning and application of epoxide hydrolases from yeasts

    NARCIS (Netherlands)

    Visser, J.H.

    2002-01-01

    Epoxides are cyclic ethers that readily react with various nucleophilic compounds. Consequently, epoxides can be used in many chemical synthesis reactions. Two enantiomeric forms of an epoxide are possible if one of the carbon atoms is chiral. This means that the epoxide is actually a racemic mixtur

  7. Epoxidation of linseed oil-Alkyd resins

    International Nuclear Information System (INIS)

    Three types of different linseed oil-alkyd resin ( Alk (I), Alk (II), and Alk (III) ) were prepared with the calculated amounts of mono glycerides and adipic acid (1:1, 1:2, and 2:1 Eq.Wt) respectively via monoglyceride method. The obtained alkyd resins were epoxidized via reaction with the calculated quantities of peracetic acid, which was prepared by the reaction of acetic anhydride with H2O2. Epoxidation occurred with the ratio (1: 1, 1 :3, and 1:6 Eq. Wt) of alkyd to peracetic acid. The effect of reaction time on the epoxy group content was measured during the epoxidation process. The prepared alkyd resins were analyzed by IR and H1NMR. The metal coated film properties of epoxidized alkyd resins were compared with those of unmodified alkyd resins. It was observed that the coating films of epoxidized alkyd resins have better in drying properties, hardness, adhesion, impact and flexibility than those of un epoxidized alkyd resins. The flammability properties of the paper coated films for the prepared brominated epoxidized alkyd resins were found to be fire retardant

  8. Gene evolution of epoxide hydrolases and recommended nomenclature

    OpenAIRE

    Beetham, J K; Grant, D; Arand, M; Garbarino, J; Kiyosue, T; Pinot, F; Oesch, F; Belknap, W R; Shinozaki, K.; Hammock, B. D.

    1995-01-01

    We have analyzed amino acid sequence relationships among soluble and microsomal epoxide hydrolases, haloacid dehalogenases, and a haloalkane dehalogenase. The amino-terminal residues (1-229) of mammalian soluble epoxide hydrolase are homologous to a haloacid dehalogenase. The carboxy-terminal residues (230-554) of mammalian soluble epoxide hydrolase are homologous to haloalkane dehalogenase, to plant soluble epoxide hydrolase, and to microsomal epoxide hydrolase. The shared identity between t...

  9. Epoxide insulation for Tokamak coils

    International Nuclear Information System (INIS)

    The construction and testing of 12-tonne toroidal-field electromagnets for the Joint European Torus by Brown Boveri and Cie (Mannheim) are described. The principle of Tokamak confinement of a plasma which acts as the secondary winding of a transformer is explained. The Cu conductors are sanded and coated with epoxide adhesive before being wrapped in 7mm thick woven glass fibre, dried by heating under vacuum, impregnated and encapsulated in 1.2 tonnes of Araldite, which is solidified under pressure of 4 atmospheres and hardened for ten hours at 1500C. The prototype withstood tests involving 25,000 flexure cycles at 1.1 MN and 2 Hz, 2,000 quarter-hour 10kA heating cycles between 840 and 200C, and exposure to 500 million rads. 32 such coils were constructed at the rate of one every three weeks. (M.B.D.)

  10. Characterization of Hovi-mEH1, a microsomal epoxide hydrolase from the glassy-winged sharpshooter Homalodisca vitripennis.

    Science.gov (United States)

    Kamita, Shizuo G; Oshita, Grant H; Wang, Peng; Morisseau, Christophe; Hammock, Bruce D; Nandety, Raja Sekhar; Falk, Bryce W

    2013-08-01

    Epoxide hydrolase (EH) is an enzyme in the α/β-hydrolase fold superfamily that uses a water molecule to transform an epoxide to its corresponding diol. In insects, EHs metabolize among other things critical developmental hormones called juvenile hormones (JHs). EHs also play roles in the detoxification of toxic compounds that are found in the insect's diet or environment. In this study, a full-length cDNA encoding an epoxide hydrolase, Hovi-mEH1, was obtained from the xylem-feeding insect Homalodisca vitripennis. H. vitripennis, commonly known as the glassy-winged sharpshooter, is an economically important vector of plant pathogenic bacteria such as Xylella fastidiosa. Hovi-mEH1 hydrolyzed the general EH substrates cis-stilbene oxide and trans-diphenylpropene oxide with specific activities of 47.5 ± 6.2 and 1.3 ± 0.5 nmol of diol formed min⁻¹ mg⁻¹, respectively. Hovi-mEH1 metabolized JH III with a Vmax of 29.3 ± 1.6 nmol min⁻¹ mg⁻¹, kcat of 0.03 s⁻¹, and KM of 13.8 ± 2.0 μM. These Vmax and kcat values are similar to those of known JH metabolizing EHs from lepidopteran and coleopteran insects. Hovi-mEH1 showed 99.1% identity to one of three predicted EH-encoding sequences that were identified in the transcriptome of H. vitripennis. Of these three sequences only Hovi-mEH1 clustered with known JH metabolizing EHs. On the basis of biochemical, phylogenetic, and transcriptome analyses, we hypothesize that Hovi-mEH1 is a biologically relevant JH-metabolizing enzyme in H. vitripennis. PMID:23704009

  11. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  12. Catalytic Enantioselective Conversion of Epoxides to Thiiranes.

    Science.gov (United States)

    Liao, Saihu; Leutzsch, Markus; Monaco, Mattia Riccardo; List, Benjamin

    2016-04-27

    A highly efficient and enantioselective Brønsted acid catalyzed conversion of epoxides to thiiranes has been developed. The reaction proceeds in a kinetic resolution, furnishing both epoxide and thiirane in high yields and enantiomeric purity. Heterodimer formation between the catalyst and sulfur donor affords an effective way to prevent catalyst decomposition and enables catalyst loadings as low as 0.01 mol %. PMID:27070207

  13. Reaction of cyclic epoxide compounds with triphenylphosphine

    International Nuclear Information System (INIS)

    Significant differences were found in the reactivity of a series of epoxides of cycloalkenes and methylenecycloalkanes and diepoxides in reaction with triphenylphosphine, depending both on the steric effects of the cyclic fragments and on their strain. The level of the strain can be judged indirectly from the chemical shifts of the 1H and 13C nuclei and the spin-spin coupling constants of the C-H bonds in the epoxide ring

  14. Free radicals of benzo(a)pyrene and derivatives.

    OpenAIRE

    Sullivan, P D

    1985-01-01

    The evidence for biological involvement, the spectroscopic properties (especially EPR), and the reactions, of free radicals derived from benzo(a)pyrene and its methylated, hydroxylated, and fluorinated derivatives are reviewed.

  15. Development of analytical methods for the gas chromatographic determination of 1,2-epoxy-3-butene, 1,2:3,4-diepoxybutane, 3-butene-1,2-diol, 3,4-epoxybutane-1,2-diol and crotonaldehyde from perfusate samples of 1,3-butadiene exposed isolated mouse and rat livers

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, S.; Schuster, A.; Filser, J.G.

    2003-07-01

    Mutagenicity and carcinogenicity of 1,3-butadiene (BD) highly probably results from epoxide metabolites as 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB) and 3,4-epoxybutane-1,2-diol (EBD). A further metabolite crotonaldehyde (CA) has also been discussed to be relevant. So far, in BD exposed rodents only EB and DEB concentrations had been quantified. However, the methods used were either not very sensitive or instrumentally expensive. Therefore, the goal of the present work was to establish simple analytical methods selective and sensitive enough to determine all of these compounds and a further secondary BD intermediate, 3-butene-1,2-diol (B-diol), in BD exposed rodent livers. The once-through perfused liver system was chosen for testing the applicability of the methods to be developed, since it enables BD exposures of this quantitatively most relevant metabolising organ near to the in-vivo situation. All the metabolites were extracted from the aqueous perfusion medium and analysed using a gas chromatograph equipped with a mass selective detector (GC/MS) in the PCI mode. (orig.)

  16. 40 CFR 721.2673 - Aromatic epoxide resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aromatic epoxide resin (generic). 721... Substances § 721.2673 Aromatic epoxide resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aromatic epoxide resin (PMN...

  17. 40 CFR 721.2685 - Polyisobutene epoxide (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyisobutene epoxide (generic). 721... Substances § 721.2685 Polyisobutene epoxide (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified generically as polyisobutene epoxide (PMNs...

  18. 40 CFR 721.2675 - Perfluoroalkyl epoxide (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Perfluoroalkyl epoxide (generic name... Substances § 721.2675 Perfluoroalkyl epoxide (generic name). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as perfluoroalkyl epoxide (PMN...

  19. Epoxidation of Palm Kernel Oil Fatty Acids

    OpenAIRE

    Michelle Ni Fong Fong; Jumat Salimon

    2013-01-01

    Epoxidation of palm kernel oil fatty acids using formic acid and hydrogen peroxide was carried out effectively using a homogeneous reaction. It was found that epoxidation reaction occurred optimally at a temperature of 40oC and reaction time of 120 minits. The oxirane conversion was the highest at 1.46mol and 0.85mol of hydrogen peroxide and formic acid respectively. It was found that a maximum of 99% relative conversion of ethylenic oxirane was obtained, similar to the conversion of iodine v...

  20. DFT Study of the Molybdenum-Catalyzed Deoxydehydration of Vicinal Diols

    DEFF Research Database (Denmark)

    Lupp, Daniel; Christensen, Niels Johan; Dethlefsen, Johannes Rytter; Fristrup, Peter

    2015-01-01

    The mechanism of the molybdenum-catalyzed deoxydehydration (DODH) of vicinal diols has been investigated using density functional theory. The proposed catalytic cycle involves condensation of the diol with an MoVI oxo complex, oxidative cleavage of the diol resulting in an MoIV complex, and extru...

  1. Peroxidatic oxidation of benzo(a)pyrene and prostaglandin biosynthesis

    International Nuclear Information System (INIS)

    The arachidonic acid dependent oxidation of benzo[a]pyrene to a mixture of 3,6-, 1,6-, and 6,12-quinones has been studied by using enzyme preparations from sheep seminal vesicles. Maximal oxidation is observed at 100 μM benzo[a]pyrene and 150 μM arachiodinic acid. The arachidonic acid dependent oxidation is peroxidatic and utilizes prostaglandin G2 (PGG2), generated in situ from arachidonate, as the hydroperoxide substrate. 15-Hydroperoxy-5,8,11,13-eicosatetraenoic acid is equivalent to PGG2 as a hydroperoxide substrate, but hydrogen peroxide, cumene hydroperoxide, and tert-butyl hydroperoxide are much poorer substrates. Arachidonic acid dependent benzo[a]pyrene oxidation by microsomal and solubilized enzyme preparations is markedly stimulated by a variety of hemes and heme proteins. This is not due to the previously reported heme stimulation of prostaglandin biosynthesis [Yoshimoto, A., Ito, H., and Tomita, K. (1970) J. Biochem. (Tokyo) 68, 487-499]. Instead, the hemes function directly as peroxidases utilizing fatty acids hydroperoxides as substrates. The incubation of PGG2 with commercial methemoglobin in the absence of any other protein gives rise to significant benzo[a]pyrene oxidation to quinones. The widespread occurrence of heme proteins in animal tissue suggests that the peroxidatic oxidation of benzo[a]pyrene will be significant in any tissue that makes appreciable concentrations of fatty acid hydroperoxides

  2. Titanium impregnated borosilicate zeolites for epoxidation catalysis

    Czech Academy of Sciences Publication Activity Database

    Přech, Jan; Vitvarová, Dana; Lupínková, Lenka; Kubů, Martin; Čejka, Jiří

    2015-01-01

    Roč. 212, AUG 2015 (2015), s. 28-34. ISSN 1387-1811 R&D Projects: GA ČR GAP106/11/0819 Institutional support: RVO:61388955 Keywords : borosilicate * titanium impregnation * epoxidation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.453, year: 2014

  3. Montmorillonite modification by quaternary ammonium epoxide

    Czech Academy of Sciences Publication Activity Database

    Duchek, P.; Špírková, Milena; Šabata, Stanislav

    Kochi: India n Society of Nanoscience And Nanotechnology, 2010. s. 1. [Nanotech India 2010. 19.11.2010-21.11.2010, Kochi] R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40720504 Keywords : montmorillonite * quaternary ammonium epoxide * intercalation Subject RIV: JI - Composite Materials

  4. Efficient epoxidation of propene using molecular catalysts

    DEFF Research Database (Denmark)

    Markovits, Iulius I. E.; Anthofer, Michael H.; Kolding, Helene; Cokoja, Mirza; Pöthig, Alexander; Raba, Andreas; Herrmann, Wolfgang A.; Fehrmann, Rasmus; Kühn, Fritz E.

    2014-01-01

    The epoxidation of propene is performed in homogeneous phase using various molecular catalysts and H2O2 or tert-butyl hydroperoxide as oxidants. A comparison between some molybdenum catalysts and methyltrioxorhenium (MTO) shows that the well known Re catalyst is the best among the examined...

  5. DIFFERENCES IN DETECTION OF DNA ADDUCTS IN THE 32P-POSTLABELING ASSAY AFTER EITHER 1-BUTANOL EXTRACTION OR NUCLEASE P1 TREATMENT

    Science.gov (United States)

    The use of nuclease Pl treatment and 1-butanol extraction to increase the sensitivity of the 32P-postlabe1ling assay for DNA adducts have been compared. lthough similar results were obtained with the two methods for standard adducts formed with benzo(a)pyrene diol epoxide I, nucl...

  6. Loss of VHL in RCC reduces repair and alters cellular response to benzo[a]pyrene

    Directory of Open Access Journals (Sweden)

    MartenSchults

    2013-10-01

    Full Text Available Mutations of the von Hippel-Lindau (VHL tumor suppressor gene occur in the majority of sporadic renal-cell carcinomas (RCC. Loss of VHL function is associated with stabilization of hypoxia-inducible factor α (HIFα. We and others demonstrated that there is a two-way interaction between the aryl hydrocarbon receptor, which is an important mediator in the metabolic activation and detoxification of carcinogens, and the HIF1-pathway leading to an increased genetic instability when both pathways are simultaneously activated. The aim of this study was to investigate how environmental carcinogens, such as benzo[a]pyrene (BaP, which can be metabolically activated to BaP-7,8-diOH-9,10-epoxide (BPDE play a role in the etiology of renal-cell carcinomas (RCC. We exposed VHL deficient RCC4 cells, in which HIFα is stabilized regardless of oxygen tension, to 0.1µM BaP for 18 hours. The mutagenic BPDE-DNA adduct levels were increased in HIFα stabilized cells. Using qRT-PCR, we demonstrated that absence of VHL significantly induced the mRNA levels of AhR downstream target CYP1A1. Furthermore, HPLC analysis indicated that loss of VHL increased the concentration of BaP-7,8-dihydroxydiol, the pre-cursor metabolite of BPDE. Interestingly, the capacity to repair BPDE-DNA adducts in the HIFα stabilized RCC4 cells, was markedly reduced. Taken together, these data indicate that loss of VHL affects BaP-mediated genotoxic responses in renal-cell carcinoma and decreases repair capacity.

  7. Alterations in the metabolism of benzo(a)pyrene in syrian hamster embryo (SHE) cells pretreated with phenolic antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Strniste, G.F.; Okinaka, R.T.; Chen, D.J.

    1983-01-01

    Inhibition of chemical- or raddiation-induced neoplasia has been observed in animals whose diets were supplemented with antioxidants commonly used as food additives. Inhibition of the carcinogenicity of benzo(a)pyrene (BaP) or of 7,12-dimenthylbenz(a)anthracene (DMBA) - in rats has been achieved by the addition of the phenolic antioxidants butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT) to the diet. Our data suggest that in SHE cells antioxidants inhibit the overall metabolism of BaP to its various oxidized moieties including 7,8-diol- and 7,8,9,10-tetrol-BaP. A plausible explanation for our results with SHE cells is that the antioxidants interact directly with AHH, thus inhibiting AHH metabolic capacity. From analysis of nuclear material from SHE cells (+- antioxidants) incubated for 36 hours with BaP at 1 ..mu..g/ml, it is calculated that 4.6, 2.4 and 2.9 pmol BaP are bound to the DNA isolated from 10/sup 7/ nuclei of control, BHA-(20 ..mu..g/ml) and p-MP-(10 ..mu..g/ml) treated cultures, respectively.

  8. Preparation and characterization of bifunctional oxidative and acidic catalysts Nb2O5/TS-1 for synthesis of diols

    International Nuclear Information System (INIS)

    Bifunctional oxidative and acidic catalyst was prepared by incorporation of titanium ion (Ti4+) and niobic acid in zeolite molecular-sieve. The catalysts being active both in oxidation reactions due to the presence of tetrahedral Ti4+, and acid-catalyzed reactions due to the presence of niobic acid. Nb/TS-1 was prepared by hydrothermal synthesis of TS-1, calcination in air and subsequent impregnation of niobium into TS-1. The sample was characterized by XRD, FTIR, UV-vis DR, TPR and pyridine adsorption techniques. The XRD analysis of Nb/TS-1 revealed that the MFI structure of the TS-1 support was found to be intact upon incorporation of niobium. The infrared spectra showed that the tetrahedral titanium in the TS-1 is still remained after impregnation with niobium while based on the UV-vis DR result, the niobium species are in the octahedral structure. On the basis TPR and infrared of hydroxyl groups results, it is concluded that niobium species interacted with the silanols on the surface of TS-1. Pyridine adsorption study shows both Bronsted and Lewis acid sites are present in Nb/TS-1. The catalytic results in the transformation of 1-octene to 1,2-octanediol through the formation of 1,2-epoxyoctane by using Nb/TS-1 indicate that the production of epoxide and diol was correlated with the presence of oxidative and Bronsted acidic sites in the catalyst

  9. A xanthanolide diol and a dimeric xanthanolide from Xanthium species.

    Science.gov (United States)

    Ahmed, A A; Mahmoud, A A; El-Gamal, A A

    1999-06-01

    Extracts of the aerial parts of Xanthium strumarium and fruit of X. pungens afforded a new Xanthanolide diol derivative, 11alpha,13-dihydroxyxanthatin and a new dimeric xanthanolide sesquiterpene lactone, pungiolide C, in addition to some known compounds. The structures of the new compounds were determined by spectroscopic methods particularly high resolution (1)H-, (13)C-NMR and 2D (1)H- (1)H and (1)H- (13)C COSY NMR analysis. PMID:17260271

  10. Epoxide resins for use at low temperatures

    International Nuclear Information System (INIS)

    This chapter reports on the development and characterization of a number of unfilled epoxide resin systems offering improved resistance to thermal shock. Points out that the low temperature physical properties of cured resin systems are little changed by formulation variables. Finds that it is during cool down from room temperature that these newly developed resin systems demonstrate their ability to absorb the strains induced by differential thermal contraction. Concludes that the new epoxide resin systems demonstrate excellent resistance to thermal shock and have impregnation characteristics suitable for the preparation of fiber reinforced composites by vacuum impregnation or by wet lay up procedures. Notes that their improved resistance to thermal shock allows them to be used in situations where some inhomogeneity of reinforcement is unavoidable or where large temperature gradients may be present. Recommends that polymers used in low temperature applications should contain, wherever possible, reinforcement in the form of glass fabrics, rovings or chopped strands

  11. Determination of the kinetics of ethene epoxidation

    OpenAIRE

    Schouten, E.P.S.; Borman, P.C.; Westerterp, K.R.

    1996-01-01

    Several problems and pitfalls in the use of laboratory reactors for the determination of the kinetics of ethene epoxidation over industrial silver on α-alumina catalyst are discussed. Also, commonly used methodologies for kinetic studies are dealt with because of the general nature of some problems. Some advice is given in choosing and using the appropriate reactor type. Further, a method is discussed to determine kinetics in a cooled tubular reactor without having to use heat transport relat...

  12. Epoxide composite materials with carbon nanotubes

    International Nuclear Information System (INIS)

    Methods of formation and physical properties of epoxide composite materials reinforced with carbon nanotubes are considered. An analogy is made between the relaxation properties of carbon nanotubes and macromolecules. The concentration dependences of the electrical conductivity of the epoxy polymers filled with single-walled and multi-walled carbon nanotubes are discussed. Modern views on the mechanism of reinforcement of polymers with nanotubes are outlined. The bibliography includes 143 references.

  13. Inhibition of epoxide hydrolase by valproic acid in epileptic patients receiving carbamazepine.

    OpenAIRE

    Robbins, D K; Wedlund, P J; Kuhn, R.; Baumann, R J; Levy, R.H.; Chang, S.L.

    1990-01-01

    The effect of valproic acid (VPA) on the disposition of carbamazepine-10,11-epoxide (epoxide) was studied in five epileptic patients on chronic carbamazepine (CBZ) therapy. The individual pharmacokinetic parameters influencing epoxide disposition were determined in the presence and absence of VPA. VPA significantly decreased the clearance of unbound epoxide (an in vivo index of epoxide hydrolase activity), but did not appear to affect epoxide formation. VPA also increased the free concentrati...

  14. The ERβ ligand 5α-androstane, 3β,17β-diol (3β-diol) regulates hypothalamic oxytocin (Oxt) gene expression.

    Science.gov (United States)

    Sharma, Dharmendra; Handa, Robert J; Uht, Rosalie M

    2012-05-01

    The endocrine component of the stress response is regulated by glucocorticoids and sex steroids. Testosterone down-regulates hypothalamic-pituitary-adrenal (HPA) axis activity; however, the mechanisms by which it does so are poorly understood. A candidate testosterone target is the oxytocin gene (Oxt), given that it too inhibits HPA activity. Within the paraventricular nucleus of the hypothalamus, oxytocinergic neurons involved in regulating the stress response do not express androgen receptors but do express estrogen receptor-β (ERβ), which binds the dihydrotestosterone metabolite 3β,17β-diol (3β-diol). Testosterone regulation of the HPA axis thus appears to involve the conversion to the ERβ-selective ligand 5α-androstane, 3β-diol. To study mechanisms by which 3β-diol could regulate Oxt expression, we used a hypothalamic neuronal cell line derived from embryonic mice that expresses Oxt constitutively and compared 3β-diol with estradiol (E2) effects. E2 and 3β-diol elicited a phasic response in Oxt mRNA levels. In the presence of either ligand, Oxt mRNA levels were increased for at least 60 min and returned to baseline by 2 h. ERβ occupancy preceded an increase in Oxt mRNA levels in the presence of 3β-diol but not E2. In tandem with ERβ occupancy, 3β-diol increased occupancy of the Oxt promoter by cAMP response element-binding protein and steroid receptor coactivator-1 at 30 min. At the same time, 3β-diol led to the increased acetylation of histone H4 but not H3. Taken together, the data suggest that in the presence of 3β-diol, ERβ associates with cAMP response element-binding protein and steroid receptor coactivator-1 to form a functional complex that drives Oxt gene expression. PMID:22434086

  15. The electron-impact promoted fragmentation of aurone epoxides.

    Science.gov (United States)

    Brady, B. A.; O'Sullivan, W. I.; Duffield, A. M.

    1972-01-01

    The mass spectra of six aurone epoxides have been rationalized with the aid of high resolution mass spectrometry and metastable ion evidence. These compounds fragment in a well defined manner and mechanisms are proposed for the formation of their characteristic ions. Some similarity was observed between the mass spectra of 6-methoxyaurone epoxide (II), 4-hydroxy-7-methoxy-3-phenylcoumarin (VII) and 7-methoxyflavonol (IX). The possibility that VII and IX are intermediates in the fragmentation of epoxide II is discussed. Thermal rearrangement of aurone epoxide II was shown to yield the corresponding flavonol IX and coumarin VII.

  16. Simple Epoxide Formation for the Organic Laboratory Using Oxone

    Science.gov (United States)

    Broshears, Williams C.; Esteb, John J.; Richter, Jeremy; Wilson, Anne M.

    2004-01-01

    Epoxide chemistry is widely used in organic synthesis and regularly discussed in organic chemistry textbooks. An experiment to generate dimethyldioxirane in situ from acetone using Oxone is explained.

  17. Kinetics and mechanism of the oxidation of some diols by benzyltrimethylammonium tribromide

    Indian Academy of Sciences (India)

    Garima Goswami; Seema Kothari; Kalyan K Banerji

    2001-02-01

    The kinetics of oxidation of five vicinal and four non-vicinal diols, and two of their monoethers by benzyltrimethylammonium tribromide (BTMAB) have been studied in 3:7 (/) acetic acid-water mixture. The vicinal diols yield the carbonyl compounds arising out of the glycol bond fission while the other diols give the hydroxycarbonyl compounds. The reaction is first-order with respect to BTMAB. Michaelis-Menten type kinetics is observed with respect to diol. Addition of benzyltrimethylammonium chloride does not affect the rate. Tribromide ion is postulated to be the reactive oxidizing species. Oxidation of [1,1,2,2-2H4] ethanediol shows the absence of a kinetic isotope effect. The reaction exhibits substantial solvent isotope effect. A mechanism involving a glycol-bond fission has been proposed for the oxidation of the vicinal diols. The other diols are oxidized by a hydride ion transfer to the oxidant, as are the monohydric alcohols.

  18. Modulatory effects of catechin hydrate against genotoxicity, oxidative stress, inflammation and apoptosis induced by benzo(a)pyrene in mice.

    Science.gov (United States)

    Shahid, Ayaz; Ali, Rashid; Ali, Nemat; Hasan, Syed Kazim; Bernwal, Preeti; Afzal, Shekh Mohammad; Vafa, Abul; Sultana, Sarwat

    2016-06-01

    Benzo(a)pyrene [B(a)P], a polycyclic aromatic hydrocarbon (PAH) is a strong mutagen and potent carcinogen. The aim of the present study was to investigate the efficacy of catechin hydrate against B(a)P induced genotoxicity, oxidative stress, inflammation, apoptosis and to explore its underlying molecular mechanisms in the lungs of Swiss albino mice. Administration of B(a)P (125 mg/kg b. wt., p. o.) increased the activities of toxicity markers such as LPO, LDH and B(a)P metabolizing enzymes [NADPH-cytochrome P450 reductase (CYPOR) and microsomal epoxide hydrolase (mEH)] with subsequent decrease in the activities of tissue anti-oxidant armory (SOD, CAT, GPx, GR, GST, QR and GSH). It also caused DNA damage and activation of apoptotic and inflammatory pathway by upregulation of TNF-α, IL-6, NF-kB, COX-2, p53, bax, caspase-3 and down regulating Bcl-2. However, pre-treatment with catechin at a dose of 20 and 40 mg/kg significantly decreased LDH, LPO, B(a)P metabolizing enzymes and increased anti-oxidant armory as well as regulated apoptosis and inflammation in lungs. Histological results also supported the protective effects of catechin. The findings of the present studies suggested that catechin as an effective natural product attenuates B(a)P induced lung toxicity. PMID:27020533

  19. The Epoxidation of Limonene over the TS-1 and Ti-SBA-15 Catalysts

    Directory of Open Access Journals (Sweden)

    Agnieszka Wróblewska

    2014-11-01

    Full Text Available Limonene belongs to a group of very important intermediates used in the production of fine chemicals. This monoterpene compound can be obtained from peels of oranges or lemon which are a (biomass waste from the orange juice industry. Thus, limonene is a renewable, easy available and a relatively cheap compound. This work presents preliminary studies on the process of limonene epoxidation over zeolite type catalysts such as: TS-1 and Ti-SBA-15. In these studies methanol was used as a solvent and as an oxidizing agent a 60 wt % hydrogen peroxide solution was applied. The activity of each catalyst was investigated for four chosen temperatures (0 °C, 40 °C, 80 °C and 120 °C. The reaction time was changed from 0.5 to 24 h. For each catalyst the most beneficial conditions (the appropriate temperature and the reaction time have been established. The obtained results were compared and the most active catalyst was chosen. These studies have also shown different possible ways of limonene transformation, not only in the direction of 1,2-epoxylimonene and its corresponding diol, but also in direction of carveol, carvone and perillyl alcohol—compounds with a lot of applications. The possible mechanisms of formation of the allylic oxidation products were proposed.

  20. Synthesis and characterizations of degradable aliphatic-aromatic copolyesters from lactic acid, dimethyl terephthalate and diol: Effects of diol type and monomer feed ratio

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available Lactic acid-based aliphatic/aromatic copolyesters are synthesized to incorporate the degradability of polylactic acid and good mechanical properties of aromatic species by using polycondensation of lactic acid (LA, dimethyl terephthalate (DMT, and various diols. Effects of diol lengths and comonomer feed ratios on structure and properties of the resulting copolymers are investigated. Three types of diols with different methylene lengths are employed, i.e., ethylene glycol (EG, 1,3-propanediol (PD and 1,4-butanediol (BD. LA/DMT/diol feed ratios of 2:1:2, 1:1:2, and 1:2:4 are used in each diol system. It is found that types of the diols play an important role in the properties of the copolyester, where an increase in diol length results in an increase in the copolymers molecular weight, and a decrease in Tg, Tm and crystallinity, when a constant monomer feed ratio is employed. Monomer feed ratio also has a significant effect on properties of the copolymers, where an increase in the aromatic content leads to formation of copolymers with higher molecular weight, longer aromatic block sequence and high aromatic to aliphatic ratio in the chain structure. These, in turn, lead to an increase in Tg, Tm, crystallinity and thermal stability of the copolymer samples, and a reduction in their solubility.

  1. Environmental DNA as a source of a novel epoxide hydrolase reacting with aliphatic terminal epoxides

    Czech Academy of Sciences Publication Activity Database

    Kotík, Michael; Štěpánek, Václav; Marešová, Helena; Kyslík, Pavel; Archelas, A.

    2009-01-01

    Roč. 56, č. 4 (2009), s. 288-293. ISSN 1381-1177 R&D Projects: GA ČR GA204/06/0458 Institutional research plan: CEZ:AV0Z50200510 Keywords : environmental DNA * metagenome * epoxide hydrolase Subject RIV: EE - Microbiology, Virology Impact factor: 2.400, year: 2009

  2. Production of phosphorous-containing oleochemicals through an epoxide route

    Science.gov (United States)

    Phosphorous was incorporated into the middle of the fatty chain on a methyl ester utilizing an epoxide route. Methyl oleate was epoxidized and then a catalyzed or uncatalyzed ring opening reaction was performed using dibutyl phosphate in order to synthesize a butyl dioxaphospholane-containing deriv...

  3. Identification of Epoxide-Derived Metabolite(s) of Benzbromarone.

    Science.gov (United States)

    Wang, Kai; Wang, Hui; Peng, Ying; Zheng, Jiang

    2016-04-01

    Benzbromarone (BBR) is a benzofuran derivative that has been quite useful for the treatment of gout; however, it was withdrawn from European markets in 2003 because of reported serious incidents of drug-induced liver injury. BBR-induced hepatotoxicity has been suggested to be associated with the formation of a quinone intermediate. The present study reported epoxide-derived intermediate(s) of BBR. An N-acetylcysteine (NAC) conjugate derived from epoxide metabolite(s) was detected in both microsomal incubations of BBR and urine samples of mice treated with BBR. The NAC conjugate was identified as 6-NAC BBR. Ketoconazole suppressed the bioactivation of BBR to the epoxide intermediate(s), and the CYP3A subfamily was the primary enzyme responsible for the formation of the epoxide(s). The present study provided new information on metabolic activation of BBR. PMID:26792818

  4. Flow cytometric measurement of the metabolism of benzo [a] pyrene by mouse liver cells in culture

    International Nuclear Information System (INIS)

    The metabolism of benzo[a]pyrene in individual cells was monitored by flow cytometry. The measurements are based on the alterations that occur in the fluorescence emission spectrum of benzo[a]pyrene when it is converted to various metabolities. Using present instrumentation the technique could easily detect 1 x 10/sup 6/ molecules per cells of benzo [a]pyrene and 1 x 10/sup 7/ molecules per cell of the diol epoxide. The analysis of C3H IOT 1/2 mouse fibroblasts growing in culture indicated that there was heterogeneity in the conversion of the parent compound into diol epoxide derivative suggesting that some variation in sensitivity to transformation by benzo[a]pyrene may be due to differences in cellular metabolism

  5. Mechanisms in homogeneous and heterogeneous epoxidation catalysis

    CERN Document Server

    Oyama, S Ted

    2011-01-01

    The catalytic epoxidation of olefins plays an important role in the industrial production of several commodity compounds, as well as in the synthesis of many intermediates, fine chemicals, and pharmaceuticals. The scale of production ranges from millions of tons per year to a few grams per year. The diversity of catalysts is large and encompasses all the known categories of catalyst type: homogeneous, heterogeneous, and biological. This book summarizes the current status in these fields concentrating on rates, kinetics, and reaction mechanisms, but also covers broad topics including modeli

  6. Epoxide resins for use at low temperatures

    International Nuclear Information System (INIS)

    A simple screening test is presented which permits the rapid evaluation of many epoxide resin systems, with a subsequent more detailed evaluation of those which performed well in the test. Several hundred resin systems were investigated including such variables as hardened ratios and blends, diluents, flexibilisers and modifiers, but considering only one expoxide resin, namely diglycidyl ether of Bisphenol A. The materials and results are detailed and conclusions formulated. Polymers used in low temperature applications should contain, wherever possible, reinforcement in the form of glass fabrics, rovings or chopped strands. Further work is planned to assess the performance of these materials when used with fillers and in laminates in fatigue situations

  7. Syntheses of surfactants from oleochemical epoxides

    Directory of Open Access Journals (Sweden)

    Warwel Siegfried

    2001-01-01

    Full Text Available Sugar-based surfactants were obtained in good yields (up to 100% under mild conditions (70°C, methanol or mixtures of methanol and water by ring-opening of terminal epoxides with aminopolyols, derived from glucose. Reaction of N-methyl glucamine with epoxides from even-numbered C4-C18 alpha-olefins or from terminal unsaturated fatty acid methyl esters leads to linear products, while corresponding reactions with N-dodecyl glucamine or glucamine yield surfactants with different Y-structures. Products obtained by conversion of omega-epoxy fatty acid methyl esters were saponificated with NaOH or hydrolyzed enzymatically to sodium salts or free acids respectively, which are amphoteric surfactants. Studies of the surfactants at different pH-values demonstrate different surface active properties in aqueous solutions. Critical micelle concentrations (c.m.c. in a range between 2 and 500mg/l and surface tensions of 25-40mN/m were measured for several of the synthesized sugar-based surfactants. The ring-opening products are rather poor foamers, whereas some of the corresponding hydrobromides show good foaming properties.

  8. Alternating polyesteramides based on 1,4-butylene terephthalamide: 2. alternating polyesteramides based on a single, linear diol (4NTm)

    NARCIS (Netherlands)

    Serrano, P.J.M.; Thuss, E.H.L.; Gaymans, R.J.

    1997-01-01

    Strictly alternating polyesteramides consisting of 1,4-butylene terephthalamide and aliphatic diols have been synthesized in the melt in the presence of a titanium catalyst. The influence of diol length on the thermal and mechanical properties was studied. Depending on its structure, the diol took p

  9. Inactivation of epoxide hydrolase by catalysis-induced formation of isoaspartate

    OpenAIRE

    van Loo, Bert; Permentier, Hjalmar P.; Kingma, Jaap; Baldascini, Helen; Janssen, Dick B.

    2008-01-01

    Epoxide hydrolases catalyze hydrolytic epoxide ring-opening, most often via formation of a covalent hydroxyalkyl-enzyme intermediate. A mutant of Agrobacterium radiobacter epoxide hydrolase, in which the phenylalanine residue that flanks the invariant catalytic aspartate nucleophile is replaced by a threonine, exhibited inactivation during conversion when the (R)-enantiomer of para-nitrostyrene epoxide was used as substrate. HPLC analysis of tryptic fragments of the epoxide hydrolase, followe...

  10. Interindividual variation in binding of benzo[a]pyrene to DNA in cultured human Bronchi

    DEFF Research Database (Denmark)

    Harris, C.C.; Autrup, Herman; Connor, R.;

    1976-01-01

    The binding of benzo[a]pyrene to DNA in cultured human bronchus was measured in specimens from 37 patients. The binding values ranged from 2 to 151 picomoles of benzo[a]pyrene per milligram of DNA with an overall mean +/- standard error of 34.2 +/- 5.2. This 75-fold interindividual variation in t...

  11. Proton irradiation effect on the properties of epoxide insulation

    International Nuclear Information System (INIS)

    Behaviour of epoxide polymers under the effect of proton irradiation has been studied. EhD-16 epoxide-dian resin was the object of investigation. The samples have been irradiated in a cyclotron with 10 MeV proton beams at a beam current density of 0,05 μA/cm2. At a dose of 105 Gy the compound structure is shown to be affected negligibly irradiation of the polymer at a dose of 107 Gy results in its aonsiderable destruction the sample durability decreasing several hundreds times. Epoxide insulation has shown good radiation stability under proton irradiation up to an absorbed radiation dose of 106 Gy

  12. Cholesterol epoxide is a direct-acting mutagen.

    OpenAIRE

    A. Sevanian; Peterson, A R

    1984-01-01

    A 24-hr treatment of V79 Chinese hamster lung fibroblasts with 12.4 microM cholesterol 5 alpha, 6 alpha-epoxide induced 8-azaguanine-resistant mutants at frequencies 4.6- to 11.8-fold higher than the spontaneous mutation rate. We show that cholesterol epoxide, which is produced by in vivo cholesterol oxidation, is a weak direct-acting mutagen. Cholesterol epoxide was found to be accumulated by cells and transformed to cholestane-3 beta, 5 alpha, 6 beta-triol, which was more toxic and a more p...

  13. Two-step biocatalytic route to biobased functional polyesters from omega-carboxy fatty acids and diols.

    Science.gov (United States)

    Yang, Yixin; Lu, Wenhua; Zhang, Xiaoyan; Xie, Wenchun; Cai, Minmin; Gross, Richard A

    2010-01-11

    Biobased omega-carboxy fatty acid monomers 1,18-cis-9-octadecenedioic, 1,22-cis-9-docosenedioic, and 1,18-cis-9,10-epoxy-octadecanedioic acids were synthesized in high conversion yields from oleic, erucic and epoxy stearic acids by whole-cell biotransformations catalyzed by C. tropicalis ATCC20962. Maximum volumetric yields in shake-flasks were 17.3, 14.2, and 19.1 g/L after 48 h conversion for oleic acid and 72 h conversions for erucic and epoxy stearic acids, respectively. Studies in fermentor with better control of pH and glucose feeding revealed that conversion of oleic acid to 1,18-cis-9-octadecenedioic acid by C. tropicalis ATCC20962 occurred with productivities up to 0.5 g/L/h. The conversion of omega-carboxy fatty acid monomers to polyesters was then studied using immobilized Candida antarctica Lipase B (N435) as catalyst. Polycondensations with diols were performed in bulk as well as in diphenyl ether. The retension of functionality from fatty acid, to omega-carboxy fatty acid monomer and to corresponding polyesters resulted in polymers with with unsaturated and epoxidized repeat units and M(w) values ranging from 25000 to 57000 g/mol. These functional groups along chains disrupted crystallization giving materials that are low melting (23-40 degrees C). In contrast, saturated polyesters prepared from 1,18-octadecanedioic acid and 1,8-octanediol have correspondingly higher melting transitions (88 degrees C). TGA results indicated that all synthesized polyesters showed high thermal stabilities. Thus, the preparation of functional monomers from C. tropicalis omega-oxidation of fatty acids provides a wide range of new monomer building blocks to construct functional polymers. PMID:20000460

  14. Synthesis, stability constants and electronic spectral studies of ternary complexes of Pr(III) with histidine and diols

    International Nuclear Information System (INIS)

    The mixed ligand complexes of the type MAB, MA2B and MaB2 where M = Pr(III), A = histidine and B = ethanediol, prop-1,2-diol, 2-butene-1, 4-diol, but-2,3-diol, pent-1,5-diol and hex-1,6-diol have been investigated by alkalimetric titrations. The overall stability constants have been evaluated at 30+1degC (μ = 0.2MKNO3). The absorption spectra of some praseodymium(III) ternary complexes in solution have been used to calculate energy interaction and intensity parameters. The low intensity of the pseudohypersensitive transition suggests higher coordination number. (author)

  15. 1-(3-Phenylisoxazol-5-ylcyclohexane-1,2-diol

    Directory of Open Access Journals (Sweden)

    Luis Astudillo

    2009-07-01

    Full Text Available In the title compound, C15H17NO3, there are two molecules in the asymmetric unit wherein the isoxazole rings make dihedral angles of 16.16 (15 and 16.79 (13° with the benzene rings, and the cyclohexane rings adopt chair conformations. In both molecules, the hydroxyl groups of the diol fragments are cis oriented, the O—C—C—O torsion angles being 60.76 (12 and −55.86 (11°. The two molecules are linked by a strong O—H...N hydrogen bond and the crystal packing is stabilized by one O—H...N and two O—H...O hydrogen bonds. An intramolecular O—H...O hydrogen bond is observed in one of the molecules.

  16. Production of molybdenum dioxo dialkyleneglycolate compositions for epoxidation of olefins

    International Nuclear Information System (INIS)

    This patent describes a method of producing an organic soluble molybdenum-containing compound, useful as a catalyst for the epoxidation of an olefinic compound with an organic hydroperoxide, which comprises reacting molybdenum trioxide with a dialkylene glycol

  17. Enantioselective Epoxide Polymerization Using a Bimetallic Cobalt Catalyst

    KAUST Repository

    Thomas, Renee M.

    2010-11-24

    A highly active enantiopure bimetallic cobalt complex was explored for the enantioselective polymerization of a variety of monosubstituted epoxides. The polymerizations were optimized for high rates and stereoselectivity, with s-factors (kfast/kslow) for most epoxides exceeding 50 and some exceeding 300, well above the threshold for preparative utility of enantiopure epoxides and isotactic polyethers. Values for mm triads of the resulting polymers are typically greater than 95%, with some even surpassing 98%. In addition, the use of a racemic catalyst allowed the preparation of isotactic polyethers in quantitative yields. The thermal properties of these isotactic polyethers are presented, with many polymers exhibiting high T m values. This is the first report of the rapid synthesis of a broad range of highly isotactic polyethers via the enantioselective polymerization of racemic epoxides. © 2010 American Chemical Society.

  18. Novel microbial epoxide hydrolases for biohydrolysis of glycidyl derivatives

    Czech Academy of Sciences Publication Activity Database

    Kotík, Michael; Břicháč, Jiří; Kyslík, Pavel

    2005-01-01

    Roč. 120, - (2005), s. 364-375. ISSN 0168-1656 Institutional research plan: CEZ:AV0Z5020903 Keywords : screening * epoxide hydrolase * biotransformation Subject RIV: EE - Microbiology, Virology Impact factor: 2.687, year: 2005

  19. Regioselective Acylation of Diols and Triols: The Cyanide Effect.

    Science.gov (United States)

    Peng, Peng; Linseis, Michael; Winter, Rainer F; Schmidt, Richard R

    2016-05-11

    Central topics of carbohydrate chemistry embrace structural modifications of carbohydrates and oligosaccharide synthesis. Both require regioselectively protected building blocks that are mainly available via indirect multistep procedures. Hence, direct protection methods targeting a specific hydroxy group are demanded. Dual hydrogen bonding will eventually differentiate between differently positioned hydroxy groups. As cyanide is capable of various kinds of hydrogen bonding and as it is a quite strong sterically nondemanding base, regioselective O-acylations should be possible at low temperatures even at sterically congested positions, thus permitting formation and also isolation of the kinetic product. Indeed, 1,2-cis-diols, having an equatorial and an axial hydroxy group, benzoyl cyanide or acetyl cyanide as an acylating agent, and DMAP as a catalyst yield at -78 °C the thermodynamically unfavorable axial O-acylation product; acyl migration is not observed under these conditions. This phenomenon was substantiated with 3,4-O-unproteced galacto- and fucopyranosides and 2,3-O-unprotected mannopyranosides. Even for 3,4,6-O-unprotected galactopyranosides as triols, axial 4-O-acylation is appreciably faster than O-acylation of the primary 6-hydroxy group. The importance of hydrogen bonding for this unusual regioselectivity could be confirmed by NMR studies and DFT calculations, which indicate favorable hydrogen bonding of cyanide to the most acidic axial hydroxy group supported by hydrogen bonding of the equatorial hydroxy group to the axial oxygen. Thus, the "cyanide effect" is due to dual hydrogen bonding of the axial hydroxy group which enhances the nucleophilicity of the respective oxygen atom, permitting an even faster reaction for diols than for mono-ols. In contrast, fluoride as a counterion favors dual hydrogen bonding to both hydroxy groups leading to equatorial O-acylation. PMID:27104625

  20. Studies on the analysis of benzo(a)pyrene and its metabolites in biological samples by using high performance liquid chromatography/fluorescence detection and gas chromatography/mass spectrometry

    International Nuclear Information System (INIS)

    An analytical method the determination of benzo(a)pyrene (BaP) and its hydroxylated metabolites, 1-hydroxybenzo(a)pyrene (1-OHBaP), 3-hydroxybenzo(a)pyrene (3-OHBaP), benzo(a)pyrene-4,5-dihydrodial(4,5-diolBaP) and benzo(a)pyrene-7,8-dihydrodiol (7,8-diolBaP), in rat urine and plasma has been developed by HPLC/FLD and GC/MS. The derivatization with alkyl iodide was employed to improve the resolution and the detection of two mono hydroxylated metabolites, 1-OHBaP and 3-OHBaP, in LC and GC. BaP and its four metabolites in spiked urine were successfully separated by gradient elution on reverse phase ODS C18 column (4.6 mm I.D., 100 mm length, particle size 5μm) using a binary mixture of MeOH/H2O (85/15, v/v) as mobile phase after ethylation at 90 .deg. C for 10 min. The extraction recoveries of BaP and its metabolites in spiked samples with liquid-liquid extraction, which was better than solid phase extraction, were in the range of 90.3-101.6% in n-hexane for urine and 95.7-106.3% in acetone for plasma, respectively. The calibration curves has shown good linearity with the correlation coefficients (R2) varying from 0.992 to 1.000 for urine and from 0.996 to 1.000 for plasma, respectively. The detection limits of all analytes were obtained in the range of 0.01-0.1 ng/mL for urine and 0.1-0.4ng/mL for plasma, respectively. The metabolites of BaP were excreted as mono hydroxy and dihydrodiol forms after intraperitoneal infection of 20 mg/kg of BaP to rats. The total amounts of BaP and four metabolites excreted in dosed rat urine were 3.79 ng over the 0 - 96 hr period from administration and the excretional recovery was less than 0.065% of the injection amounts of BaP. The proposed method was successfully applied to the determination of BaP and its hydroxylated metabolites in rat urine and plasma for the pharmacokinetic studies

  1. Organocatalytic asymmetric epoxidation and tandem epoxidation/Passerini reaction under eco-friendly reaction conditions.

    Science.gov (United States)

    Deobald, Anna Maria; Corrêa, Arlene G; Rivera, Daniel G; Paixão, Márcio Weber

    2012-10-14

    An eco-friendly synthesis of highly functionalized epoxides and their incorporation into an organocatalytic multicomponent approach are reported. For this, a modified class of diarylprolinol silyl ethers was designed to enable high catalytic activity in an environmentally benign solvent system. The one-pot procedure showed great efficiency in promoting stereoselective multicomponent transformations in a tandem, 'green' fashion. Because of its non-residual, efficient and selective character, this synthetic design shows promise for large-scale applications in both diversity and target-oriented syntheses. PMID:22918441

  2. Investigation of structural changes in modified epoxide polymers by means of positron annihilation

    International Nuclear Information System (INIS)

    Microstructure and free volume in modified epoxide polymers have been studied by means of positron annihilation, differential thermoanalysis, and uptake of water. The results obtained show that the modified epoxide polymers possess better mechanical properties than polymers not modified

  3. A screen for Benzo(apyrene in Fish Samples From Crude Oil Polluted Environments

    Directory of Open Access Journals (Sweden)

    C. Anyakora

    2008-01-01

    Full Text Available Several studies have shown that exposure to Benzo(apyrene increases the risk of cancer. In this study several fish samples from Niger the Delta region of Nigeria were screened for the presence of Benzo(apyrene. The study was carried out using Gas chromatograph coupled to a mass spectrometry detector. Benzo(apyrenes in the samples were identified through both retention time match with authentic standards and simultaneous maximization of several major ions from GC/MS data. Perylene-d12 was used as the internal standard for quantitation. Concentration of benzo(apyrene in the samples ranged from 1.47 to 10.53 µg/kg which is more than WHO recommended maximum allowable concentration. Therefore this study concludes that the population is at an elevated risk of cancer of occurrence.

  4. BENZO(A)PYRENE CONCENTRATIONS IN SOMATIC AND GONAD TISSUES OF BAY MUSSELS, 'MYTILUS EDULIS'

    Science.gov (United States)

    The purposes of the present study were to measure benzo(a)pyrene concentrations in the somatic and gonadal tissues of mytilus edulis and determine whether or not variations in those two tissue compartments could be related to seasonal fluctuations.

  5. Development of an efficient 18O epoxide labeling method: Investigation of the cytosolic expoxide hydrolase mechanism

    International Nuclear Information System (INIS)

    Mechanistic studies of Cytosolic Epoxide Hydrolase (CEH) reveal an anti opening of the epoxide arising from base catalyzed activation of H2O, possibly in concert with acidic activation of the epoxide oxygen. Preliminary data on the hydrolysis of fatty acid oxides shows the CEH is able to discriminate between chemically equivalent epoxide carbons. The research is geared toward methodology development in which CEH could be used as a organic synthetic tool, with substrate and product regio-, stereo-, and enantioselectivity

  6. Diversity and biocatalytic potential of epoxide hydrolases identified by genome analysis

    OpenAIRE

    van der Loo, B; Kingma, J.; Arand, M; Wubbolts, Marcel; Janssen, D B

    2006-01-01

    Epoxide hydrolases play an important role in the biodegradation of organic compounds and are potentially useful in enantioselective biocatalysis. An analysis of various genomic databases revealed that about 20% of sequenced organisms contain one or more putative epoxide hydrolase genes. They were found in all domains of life, and many fungi and actinobacteria contain several putative epoxide hydrolase-encoding genes. Multiple sequence alignments of epoxide hydrolases with other known and puta...

  7. Sulfuric acid as a catalyst for ring-opening of biobased bis-epoxides

    Science.gov (United States)

    Vegetable oils can be relatively and easily transformed into bio-based epoxides. Because of this, the acid-catalyzed epoxide ring-opening has been explored for the preparation of bio-based lubricants and polymers. Detailed model studies are carried out only with mono-epoxide made from methyl oleate,...

  8. Charpy impact test of cloth reinforced epoxide resin at low temperature

    International Nuclear Information System (INIS)

    Charpy impact tests are made on commercial epoxide resin, glass cloth reinforced epoxide and carbon cloth reinforced epoxide at liquid nitrogen temperature and RT. The samples are described, the tests and results presented and illustrated with relevant halftones. The effects of impact velocity and of off-axis angle on the samples are presented. Four conclusions are formulated

  9. Lithium BINOL Phosphate Catalyzed Desymmetrization of meso-Epoxides with Aromatic Thiols

    OpenAIRE

    Ingle, Gajendrasingh; Mormino, Michael G.; Antilla, Jon C.

    2014-01-01

    A highly enantioselective method for desymmetrization of meso-epoxides using thiols is reported. This is the first example of epoxide activation achieved using metal BINOL phosphates. The reaction has a broad scope in terms of epoxide substrates and aromatic thiol nucleophiles. The resulting β-hydroxyl sulfides are obtained in excellent yield and enantioselectivity.

  10. Synthesis of an Antitumoral Diarylheptanoid Containing 1,3-Diol Functionality%Synthesis of an Antitumoral Diarylheptanoid Containing 1,3-Diol Functionality

    Institute of Scientific and Technical Information of China (English)

    张少敏; 伍贻康

    2011-01-01

    A bioactive derivative of a natural diarylheptanoid containing a 1,3-anti diol motif was synthesized with the oxygen-carrying stereogenic centers taken from an enantiopure epoxy chiral building block derived from inexpensive and readily available D-glucolactone.

  11. Toxicokinetic of benzo[a]pyrene and fipronil in female green frogs (Pelophylax kl. esculentus)

    International Nuclear Information System (INIS)

    A general consensus that an increased logKow led to an increase in xenobiotic uptake and bioaccumulation is accepted. In this study we compared the toxicokinetics of two chemically different xenobiotics, i.e. benzo[a]pyrene and fipronil in female green frogs. Surprisingly, the uptake rates and the bioconcentration factors (BCF) of the two contaminants were not predicted by their logKow. The uptake rates obtained were of the same order of magnitude for the two contaminants and the BCFs measured for fipronil were about 3-fold higher than those obtained for benzo[a]pyrene. Fipronil appeared to be more recalcitrant than benzo[a]pyrene to detoxification processes leading to the accumulation of sulfone-fipronil especially in the ovaries. This phenomenon may explain reproductive influence of this contaminant described in other studies. Detoxification processes, including metabolism and the excretion of pollutants, are of importance when considering their persistence in aquatic organisms and trying to quantify their risks. Highlights: ► The uptake of benzo[a]pyrene is 1.5–3 times higher than for fipronil. ► Fipronil was more recalcitrant than benzo[a]pyrene to detoxification processes. ► This lead to increased-bioaccumulation factors except in excretion organs. ► Amphibians can be used as biomonitors for persistent pollutants. - Fipronil is more recalcitrant than benzo[a]pyrene to detoxification processes in frog.

  12. Effect of solvents on propylene epoxidation over TS-1 catalyst

    Institute of Scientific and Technical Information of China (English)

    Yulong WU; Qingshan LIU; Xueli SU; Zhentao MI

    2008-01-01

    Solvents have an important effect on the epoxidation of propylene catalyzed by TS-1. The experimental results show that, in different solvents, the catalytic activity of epoxidation is in the following order: methanol > 2-propanol > 2-butanol > acetoni-trile > acetone > tetrahydrofuran. Based on the reaction mechanism, the effects of solvents on the epoxidation were studied from eight aspects, which included the electronic effect, the steric effect, the polarity of solvent, the effect of solvent on sorption and diffusion of reactant, the oxidation of alcohol, the etherification of PO, the deactivation of TS-1 and the solubility of propylene in the solvents. The electronic effect, steric effect and the polarity of solvent were considered to be the main aspects. This work may provide theoretical guidance for choosing solvents for these kinds of reactions and also may serve as basis for further industrialization.

  13. Epoxidation of limonene over Ti MCM 41 and Ti BETA

    International Nuclear Information System (INIS)

    Ti MCM 41 were synthesized and evaluated in the epoxidation of limonene, using peroxide of hydrogen (H2O) as agent oxidizer. The characteristic hexagonal phase of Ti MCM 41 was obtained by heating the precursor gel during three days at 100 centigrade degrees. Further heating up to ten days leads to a decrease of this phase. The increase (Ti) in the synthesis gel also decreases that phase. The increase of Ti in the synthesis gel also decreases that phase UV VIS and FTIR spectroscopy indicates that Ti was incorporated in the lattice of Ti MCM 41 as well as, in Ti BETA. SEM micrographs of Ti MCM 41 show that the morphology changes with the Ti loading. Ti MCM 41 was most active than Ti BETA for limonene epoxidation even though both show high selectivity to epoxides

  14. Synthesis and Tribological Studies of Branched Alcohol Derived Epoxidized Biodiesel

    Directory of Open Access Journals (Sweden)

    Qinggong Ren

    2015-09-01

    Full Text Available The optimization and kinetics of the ring-opening reaction of an epoxidized biodiesel (epoxidized rapeseed oil methyl ester (EBD with 2-ethyl hexanol (2-EH were studied. The determined optimum conditions were 4:1 2-EH/oil molar ratio, 90 °C, 18 h, and 7 wt % of Amberlyst D001 (dry catalyst; the product’s oxirane oxygen content was 0.081% with 38.32 mm2/s viscosity at 40 °C. The catalyst retained its high catalytic power after recycling five times. Furthermore, the determined non-catalyzed activation energy was 76 kJ·mol−1 and 54 kJ·mol−1 with the D001 resin catalyst. The product’s chemical structure was investigated through FT-IR and 1H NMR. The viscosity, flash point, pour point, and anti-wear properties of the product were improved compared with those of epoxidized biodiesel.

  15. Biocompatibility of epoxidized styrene-butadiene-styrene block copolymer membrane

    International Nuclear Information System (INIS)

    Styrene-butadiene-styrene block copolymer (SBS) membrane was prepared by solution casting method and then was epoxidized with peroxyformic acid generated in situ to yield the epoxidized styrene-butadiene-styrene block copolymer membrane (ESBS). The structure and properties of ESBS were characterized with infrared spectroscopy, Universal Testing Machine, differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The performances of contact angle, water content, protein adsorption, and water vapor transmission rate on ESBS membrane were determined. After epoxidation, the hydrophilicity of the membrane increased. The water vapor transmission rate of ESBS membrane is similar to human skin. The biocompatibility of ESBS membrane was evaluated with the cell culture of fibroblasts on the membrane. It revealed that the cells not only remained viable but also proliferated on the surface of the various ESBS membranes and the population doubling time for fibroblast culture decreased.

  16. Epoxide Chemistry: Guided Inquiry Experiment Emphasizing Structure Determination and Mechanism

    Science.gov (United States)

    Krishnamurty, H. G.; Jain, Niveta; Samby, Kiran

    2000-04-01

    This paper presents an operationally simple three-step synthesis of an a-hydroxy acid based on epoxide chemistry. The focus of the experiment is on the preparation of the chalcone epoxide and its reaction with hot alcoholic alkali. The experiment leads to an unpredicted reaction product. Its structure is established as 2-benzyl-2-phenylglycollic acid by chemical and spectroscopic analysis. The hydroxyacid is a good example to bring home an important NMR principle: the nonequivalence of hydrogens adjacent to a stereogenic center. The formation of the alpha-hydroxy acid is a mechanistic puzzle. A stepwise mechanism can be developed applying lecture-based organic chemistry concepts. On the other hand, acid-catalyzed (H2SO4, BF3) reaction of the chalcone epoxide gives benzoylphenylacetaldehyde. The exercise can be used as a multistep organic chemistry experiment. It also gives students a research-type experience.

  17. Electrocatalytic aerobic epoxidation of alkenes: Experimental and DFT investigation

    International Nuclear Information System (INIS)

    A new method for electrocatalytic aerobic epoxidation of alkenes catalyzed by binuclear Cu(II) complexes with azomethine ligands based on 2,6-diformyl-4-tert-butylphenol is described. In acetonitrile–water (5%), at the potential of CuII/CuI redox couple (–0.8 V vs. Ag/AgCl/KCl) at room temperature the epoxide is obtained in an average yield of around 50%. Contrary to the majority of known epoxidations, no strong oxidants are involved and no free hydrogen peroxide is formed in the reaction, thus making it ecologically friendly. The DFT quantum-chemical modeling of the reaction mechanism revealed that a copper hydroperoxo-complex rather than hydrogen peroxide or a copper oxo-complex oxidizes alkene. The process is very selective since neither products of hydroxylation of benzene ring in styrene nor of allylic oxidation of cyclohexene were detected.

  18. Mechanism of titanocene-mediated epoxide opening through homolytic substitution

    DEFF Research Database (Denmark)

    Gansäuer, Andreas; Barchuk, Andriy; Keller, Florian; Schmitt, Martin; Grimme, Stefan; Gerenkamp, Mareike; Mück-Lichtenfeld, Christian; Daasbjerg, Kim; Svith, Heidi

    2007-01-01

    The mechanism of titanocene-mediated epoxide opening was studied by a combination of voltammetric, kinetic, computational, and synthetic methods. With the aid of electrochemical investigations the nature of a number of Ti(III) complexes in solution was established. In particular, the distribution...... of monomeric and dimeric Ti(III) species was found to be strongly affected by the exact steric conditions. The overall rate constants of the reductive epoxide opening were determined for the first time. These data were employed as the basis for computational studies of the structure and energies of...... the epoxide−titanocene complexes, the transition states of epoxide opening, and the β-titanoxy radicals formed. The results obtained provide a structural basis for the understanding of the factors determining the regioselectivity of ring opening and match the experimentally determined values. By...

  19. Reinforcing polymer composites with epoxide-grafted carbon nanotubes

    International Nuclear Information System (INIS)

    An in situ functionalization method was used to graft epoxide onto single-walled carbon nanotubes (SWNTs) and improve the integration of SWNTs into epoxy polymer. The characterization results of Raman, FT-IR and transmission electron microscopy (TEM) validated the successful functionalization with epoxide. These functionalized SWNTs were used to fabricate nanocomposites, resulting in uniform dispersion and strong interfacial bonding. The mechanical test demonstrated that, with only 1 wt% loading of functionalized SWNTs, the tensile strength of nanocomposites was improved by 40%, and Young's modulus by 60%.These results suggested that efficient load transfer has been achieved through epoxide-grafting. This investigation provided an efficient way to improve the interfacial bonding of multifunctional high-performance nanocomposites for lightweight structure material applications

  20. The oxidation of copper catalysts during ethylene epoxidation.

    Science.gov (United States)

    Greiner, M T; Jones, T E; Johnson, B E; Rocha, T C R; Wang, Z J; Armbrüster, M; Willinger, M; Knop-Gericke, A; Schlögl, R

    2015-10-14

    The oxidation of copper catalysts during ethylene epoxidation was characterized using in situ photoemission spectroscopy and electron microscopy. Gas chromatography, proton-transfer reaction mass spectrometry and electron-ionization mass spectrometry were used to characterize the catalytic properties of the oxidized copper. We find that copper corrodes during epoxidation in a 1 : 1 mixture of oxygen and ethylene. The catalyst corrosion passes through several stages, beginning with the formation of an O-terminated surface, followed by the formation of Cu2O scale and eventually a CuO scale. The oxidized catalyst exhibits measurable activity for ethylene epoxidation, but with a low selectivity of CuO powders confirm that the oxides intrinsically exhibit partial-oxidation activity. Cu2O was found to form acetaldehyde and ethylene epoxide in roughly equal amounts (1.0% and 1.2% respectively), while CuO was found to form much less ethyl aldehyde than ethylene epoxide (0.1% and 1.0%, respectively). Metallic copper catalysts were examined in extreme dilute-O2 epoxidation conditions to try and keep the catalyst from oxidizing during the reaction. It was found that in feed of 1 part O2 to 2500 parts C2H4 (PO2 = 1.2 × 10(-4) mbar) the copper surface becomes O-terminated. The O-terminated surface was found to exhibit partial-oxidation selectivity similar to that of Cu2O. With increasing O2 concentration (>8/2500) Cu2O forms and eventually covers the surface. PMID:26345450

  1. A role for the androgen metabolite, 5alpha androstane 3beta, 17beta diol (3β-diol) in the regulation of the hypothalamo-pituitary-adrenal axis.

    Science.gov (United States)

    Handa, Robert J; Sharma, Dharmendra; Uht, Rosalie

    2011-01-01

    Activation of the hypothalamo-pituitary-adrenal (HPA) axis is a basic reaction of animals to environmental perturbations that threaten homeostasis. These responses are ultimately regulated by neurons residing within the paraventricular nucleus (PVN) of the hypothalamus. Within the PVN, corticotrophin-releasing hormone (CRH), vasopressin (AVP), and oxytocin (OT) expressing neurons are critical as they can regulate both neuroendocrine and autonomic responses. Estradiol (E2) and testosterone (T) are well known reproductive hormones; however, they have also been shown to modulate stress reactivity. In rodent models, evidence shows that under some conditions E2 enhances stress activated adrenocorticotropic hormone (ACTH) and corticosterone secretion. In contrast, T decreases the gain of the HPA axis. The modulatory role of testosterone was originally thought to be via 5 alpha reduction to the potent androgen dihydrotestosterone (DHT) and its subsequent binding to the androgen receptor, whereas E2 effects were thought to be mediated by estrogen receptors alpha (ERalpha) and beta (ERbeta). However, DHT has been shown to be metabolized to the ERbeta agonist, 5α- androstane 3β, 17β Diol (3β-Diol). The actions of 3β-Diol on the HPA axis are mediated by ERbeta which inhibits the PVN response to stressors. In gonadectomized rats, ERbeta agonists reduce CORT and ACTH responses to restraint stress, an effect that is also present in wild-type but not ERbeta-knockout mice. The neurobiological mechanisms underlying the ability of ERbeta to alter HPA reactivity are not currently known. CRH, AVP, and OT have all been shown to be regulated by estradiol and recent studies indicate an important role of ERbeta in these regulatory processes. Moreover, activation of the CRH and AVP promoters has been shown to occur by 3β-Diol binding to ERbeta and this is thought to occur through alternate pathways of gene regulation. Based on available data, a novel and important role of 3β-Diol in

  2. A Role for the Androgen Metabolite, 5alpha androstane, 3beta, 17beta Diol (3b-DIol in the regulation of the hypothalamo-pituitary-adrenal axis.

    Directory of Open Access Journals (Sweden)

    Robert James Handa

    2011-11-01

    Full Text Available Activation of the hypothalamo-pituitary-adrenal (HPA axis is a basic reaction of animals to environmental perturbations that threaten homeostasis. These responses are ultimately regulated by neurons residing within the paraventricular nucleus of the hypothalamus (PVN. Within the PVN, corticotropin-releasing hormone (CRH, vasopressin (AVP and oxytocin (OT expressing neurons are critical as they can regulate both neuroendocrine and autonomic responses. Estradiol (E2 and testosterone (T are well known reproductive hormones, however, they have also been shown to modulate stress reactivity. In rodent models, evidence shows that under some conditions E2 enhances stress activated ACTH and corticosterone secretion. In contrast, T decreases the gain of the HPA axis. The modulatory role of testosterone was originally thought to be via 5 alpha reduction to the potent androgen, dihydrotestosterone, whereas E2 effects were thought to be mediated by both estrogen receptors alpha (ERα and beta (ERβ. However, DHT has been shown to be metabolized to the ERβ agonist, 5alpha- androstane 3beta,17beta diol (3b-Diol. The actions of 3β-Diol on the HPA axis are mediated by ERbeta which inhibits the PVN response to stressors. In gonadectomized rats, ERbeta agonists reduce CORT and ACTH responses to restraint stress, an effect that is also present in wild-type but not ERbeta knockout mice. The neurobiological mechanisms underlying the actions of ERbeta to alter HPA reactivity are not currently known. CRH, AVP and OT have all been shown to be regulated by estradiol and recent studies indicate an important role of ERbeta in these regulatory processes. Moreover, activation of the CRH and AVP promoters have been shown by 3β-Diol binding to ERbeta and this is thought to be through alternate pathways of gene regulation. Based on available data, a novel and important role for 3beta Diol in the regulation of the HPA axis is suggested.

  3. A Role for the Androgen Metabolite, 5alpha Androstane 3beta, 17beta Diol (3β-Diol) in the Regulation of the Hypothalamo-Pituitary–Adrenal Axis

    Science.gov (United States)

    Handa, Robert J.; Sharma, Dharmendra; Uht, Rosalie

    2011-01-01

    Activation of the hypothalamo-pituitary–adrenal (HPA) axis is a basic reaction of animals to environmental perturbations that threaten homeostasis. These responses are ultimately regulated by neurons residing within the paraventricular nucleus (PVN) of the hypothalamus. Within the PVN, corticotrophin-releasing hormone (CRH), vasopressin (AVP), and oxytocin (OT) expressing neurons are critical as they can regulate both neuroendocrine and autonomic responses. Estradiol (E2) and testosterone (T) are well known reproductive hormones; however, they have also been shown to modulate stress reactivity. In rodent models, evidence shows that under some conditions E2 enhances stress activated adrenocorticotropic hormone (ACTH) and corticosterone secretion. In contrast, T decreases the gain of the HPA axis. The modulatory role of testosterone was originally thought to be via 5 alpha reduction to the potent androgen dihydrotestosterone (DHT) and its subsequent binding to the androgen receptor, whereas E2 effects were thought to be mediated by estrogen receptors alpha (ERalpha) and beta (ERbeta). However, DHT has been shown to be metabolized to the ERbeta agonist, 5α- androstane 3β, 17β Diol (3β-Diol). The actions of 3β-Diol on the HPA axis are mediated by ERbeta which inhibits the PVN response to stressors. In gonadectomized rats, ERbeta agonists reduce CORT and ACTH responses to restraint stress, an effect that is also present in wild-type but not ERbeta-knockout mice. The neurobiological mechanisms underlying the ability of ERbeta to alter HPA reactivity are not currently known. CRH, AVP, and OT have all been shown to be regulated by estradiol and recent studies indicate an important role of ERbeta in these regulatory processes. Moreover, activation of the CRH and AVP promoters has been shown to occur by 3β-Diol binding to ERbeta and this is thought to occur through alternate pathways of gene regulation. Based on available data, a novel and important role of 3β-Diol

  4. Production of myrtanal from beta-pinene epoxide

    OpenAIRE

    Corma, Avelino; Renz, Michael; Torre Alfaro, Olalla

    2010-01-01

    [EN] The present invention relates to a procedure for the production of myrtanal from B-pinene epoxide, comprising as a minimum putting said epoxide in contact with a crystalline microporous catalyst having pores of diameter of at least 0.52 nm and having an empirical formula in dehydrated calcined form of Hw(MwTixSnyZrzSil_w_x_""d_z)02, where M is at least one metal of valency +3 selected from among Al, B, Ga, Fe, Cr, and combinations thereof; w is a molar fraction ofM having a valu...

  5. 40 CFR 63.1427 - Process vent requirements for processes using extended cookout as an epoxide emission reduction...

    Science.gov (United States)

    2010-07-01

    ... epoxide concentration using 40 CFR part 60, appendix A, Method 18. (ii) Determine the epoxide... using extended cookout as an epoxide emission reduction technique. 63.1427 Section 63.1427 Protection of... extended cookout as an epoxide emission reduction technique. (a) Applicability of extended...

  6. Experimental and DFT study of cyclodehydration and acetylation of ferrocenyl diols

    Science.gov (United States)

    Lapić, Jasmina; Višnjevac, Aleksandar; Cetina, Mario; Djaković, Senka; Vrček, Valerije; Rapić, Vladimir

    2012-07-01

    Racemic ferrocenyl diols, i.e. ferrocenyl(2-hydroxymethylphenyl)methanol (2), ferrocenyl-2-(2-hydroxymethylphenyl)ethanol (7), and ferrocenyl(2-(2-hydroxyethyl)phenyl)methanol (9) have been prepared by reduction of corresponding ketoesters using NaBH4 in a mixture EtOH and Et2O. In the course of these reactions new cyclic ethers 1-ferrocenyl-2-oxaindane (3), 3-ferrocenylisochromane (8), and 1-ferrocenylisochromane (10) have been isolated as side-products. Intramolecular cyclizations of ferrocenyl diols occur in both acidic and neutral medium. Density functional theory (BP86) calculations were used to explain the mechanism of these cyclodehydrations. Acid catalyzed reaction follows the classical SN1 mechanism, whereas the cyclodehydration in neutral medium is described as an SN2 reaction. X-ray diffraction analysis of new cyclic ether products has been performed. Monoacetates 11, 13 and 15 have been obtained in the reaction of ferrocenyl diols 2, 7, and 9, respectively, and acetic anhydride. Stereoselective acylation of racemic diols by vinyl acetate have been catalyzed by various lipases, and the best stereoselectivity has been observed for the diol 2 in the presence of Penicillium camembertii lipase.

  7. Enantioselective Synthesis of 2,2-Disubstituted Terminal Epoxides via Catalytic Asymmetric Corey-Chaykovsky Epoxidation of Ketones

    Directory of Open Access Journals (Sweden)

    Shigeki Matsunaga

    2012-02-01

    Full Text Available Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li3-BINOL complex (LLB is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (97%–91% ee and yield ( > 99%–88% from a broad range of methyl ketones with 1–5 mol% catalyst loading. Enantioselectivity was strongly dependent on the steric hindrance, and other ketones, such as ethyl ketones and propyl ketones resulted in slightly lower enantioselectivity (88%–67% ee.

  8. Benzo(a)pyrene-albumin adducts in humans exposed to polycyclic aromatic hydrocarbons in an industrial area of Poland.

    OpenAIRE

    Kure, E H; Andreassen, A; Ovrebø, S; Grzybowska, E; Fiala, Z; Strózyk, M; Chorazy, M; Haugen, A

    1997-01-01

    OBJECTIVES: The interaction of benzo(a)pyrene with serum albumin was measured in an attempt to identify the actual exposure and to evaluate albumin adduct measurements as biomarkers for exposure monitoring. METHODS: Benzo(a)pyrene-diol-epoxide (BPDE)-albumin adducts were measured by competitive enzyme linked immunosorbent assay (ELISA) in plasma of coke oven plant workers from three plants and from people living in a highly industrialised area of Silesia in Poland. Due to the high air concent...

  9. Perfluoroalkyl Epoxides: Synthesis and Conversion into Ionic Surfactants

    Directory of Open Access Journals (Sweden)

    Abdelhamid Ayari

    2014-07-01

    Full Text Available Perfluoroalkylated surfactants having a quaternary ammonium surrounded by three hydroxyl groups as hydrophilic moiety and a perfluoroalkyl chain as tail were obtained by coupling diethanolamine with perfluoroalkylated epoxide followed by quaternisation. The amphiphilic properties of these surfactants were investigated by measuring their surface and interfacial tensions.

  10. Ring-opening Polymerization of Epoxidized Soybean Oil

    Science.gov (United States)

    Ring opening polymerization of epoxidized soybean oil (ESO) initiated by boron trifluoride diethyl etherate, (BF3•OEt2), in methylene chloride was conducted in an effort to develop useful biodegradable polymers. The resulting polymers (PESO) were characterized using Infrared (IR), differential scan...

  11. Properties of epoxide hydrolase from the yeast Rhodotorula glutinis

    NARCIS (Netherlands)

    Ariës-Kronenburg, N.A.E.

    2002-01-01

     Epoxide hydrolases are ubiquitous enzymes that can be found in nearly all living organisms. Some of the enzymes play an important role in detoxifying xenobiotic and metabolic compounds. Others are important in the growth of organisms like the juvenile hormone in some insec

  12. Epoxidation of bulky organic molecules over pillared titanosilicates

    Czech Academy of Sciences Publication Activity Database

    Přech, Jan; Eliášová, Pavla; Aldhayan, D.; Kubů, Martin

    2015-01-01

    Roč. 243, APR 2014 (2015), s. 134-140. ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : Cyclooctene * Epoxidation * Layered TS-1 zeolite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  13. Synthesis of aluminum nanoparticles capped with copolymerizable epoxides

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Brandon J. [Saint Louis University, Department of Chemistry (United States); Bunker, Christopher E. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Propulsion Directorate (United States); Guliants, Elena A. [University of Dayton Research Institute, Department of Electrical and Computer Engineering (United States); Hayes, Sophia E. [Washington University, Department of Chemistry (United States); Kheyfets, Arthur [Saint Louis University, Department of Chemistry (United States); Wentz, Katherine M. [Washington University, Department of Chemistry (United States); Buckner, Steven W., E-mail: buckners@slu.edu; Jelliss, Paul A., E-mail: jellissp@slu.edu [Saint Louis University, Department of Chemistry (United States)

    2013-06-15

    We report on the synthesis of air-stable aluminum nanoparticles (Al NPs) capped with 1,2-epoxy-9-decene. Long-chain epoxides have proven to be effective capping agents for Al NPs as the epoxide ring is highly susceptible to ring-opening polymerization, leading to the formation of putative polyether loops on the nascent Al NP surface. However, these materials are observed to degrade within several hours to days following exposure to ambient air. By inducing polymerization of the additional terminal alkene functionality on the epoxide, we have produced Al NPs that exhibit both a shelf life of {approx}6 weeks and a high active Al content. Transmission electron microscopy confirms that these spherical nanostructures, {approx}25 nm in diameter, are embedded in a covalently bound polymer matrix that serves as a prophylactic barrier against water/air (H{sub 2}O/O{sub 2}) degradation, and {sup 27}Al solid-state NMR is used to nondestructively confirm the presence of both metallic Al{sup 0} and oxidized Al{sup 3+}. In addition, we have induced polymerization of the epoxide terminal alkene functionality with a long-chain diene monomer, 1,13-tetradecadiene, leading to the formation of Al NPs protected by an extremely hydrophobic polymer matrix. These core-shell nanomaterials also have high active Al contents along with extremely long shelf lives (up to 6 months upon air exposure).

  14. DEVELOPMENT OF METABOLICALLY STABLE INHIBITORS OF MAMMALIAN MICROSOMAL EPOXIDE HYDROLASE

    Science.gov (United States)

    The microsomal epoxide hydrolase (mEH) plays a significant role in the metabolism of xenobiotics such as polyaromatic toxicants. Additionally, polymorphism studies have underlined a potential role of this enzyme in relation to a number of diseases, such as emphysema, spontaneous abortion, eclampsia ...

  15. Radiation induced structural changes in an epoxide resin system

    International Nuclear Information System (INIS)

    The structural changes which occur on irradiation of an aromatic amine cured epoxide resin have been examined using UV and IR spectroscopy. The production of stable diphenyl ethylene and carbonyl groups, diphenyl cations and phenyl, phenoxyl and diphenyl radicals have been identified. Modifications to the resin system by the use of additives produces changes in the relative proportions of the species produced. (author)

  16. Peptidyl-urea based inhibitors of soluble epoxide hydrolases

    Science.gov (United States)

    We prepared a series of amino acid derived cyclohexyl and adamantyl ureas and tested them as inhibitors of the human soluble epoxide hydrolase, and obtained very potent compounds (K(I)=15nM) that are >10-fold more soluble than previously described sEH inhibitors. While our lead compound 2 showed low...

  17. Copolymerization of epoxides with anhydrides catalyzed with organic bases

    Czech Academy of Sciences Publication Activity Database

    Hošťálek, Z.; Martinez, T.; Trhlíková, Olga; Cramail, H.; Merna, J.

    Prague : J Heyrovský Institute of Physical Chemistry of the ASCR, v. v. i, 2015. OP16. ISBN 978-80-87351-37-6. [Symposium on Catalysis /47./. 02.11.2015-04.11.2015, Prague] Institutional support: RVO:61389013 Keywords : MALDI-TOF * copolymers * epoxides Subject RIV: CD - Macromolecular Chemistry

  18. Persistence of urinary excretion products of benzo(a)pyrene

    International Nuclear Information System (INIS)

    Persistence of DNA-adducts has been observed in a variety of experimental circumstances and has been suggested as one potential mechanism for explaining the long-term delay before expression of proliferative disease. In this concept, a stable DNA-adduct, which is a remnant of a prior exposure in a nondividing cell, would not express the genotoxic effect until the cells were stimulated to divide, and thus explain the long-term delay in expression of cancer. An alternative view of the observation of persistent DNA-adducts, described in this communication, is the continuing replenishment of DNA adducts by formation and turnover of these adducts from exposure to a constant supply of the ultimate carcinogenic species derived from a prior exposure. It is of interest to note that virtually all experiments where ''persistent'' adducts have been observed have been high dose exposures. During the course of experiments designed to develop improved methods for detection of DNA adducts and related derivatives derived from polynuclear aromatic hydrocarbons (PAH), we observed that there was a continuous excretion of urinary derivatives of the injected benzo(a)pyrene (BaP) beyond the initial burst of detoxification. This report describes the time dependent distribution of those derivatives in blood, urine, feces, and at the site of injection. 11 refs., 5 figs., 4 tabs

  19. [Benzo(a)pyrene contamination of vegetable oils].

    Science.gov (United States)

    Jedra, Małgorzata; Starski, Andrzej; Gawarska, Halina; Sawilska-Rautenstrauch, Dorota

    2008-01-01

    Benzo(a)pyrene (B(a)P) analysis was carried out with glass chromatographic column with alumina followed by reverse phase high-performance liquid chromatography (HPLC) and spectrofluorometric detection. B(a)P level in 40 vegetable oils were as follow: from 0.11 to 0.38 microg/kg in olive; from 0.92 to 3.74 microg/kg in rape seed oils; from 0.11 to 2.25 microg/kg in sunflower oils and from 0.33 to 1.26 microg/kg in soya oils. In another investigated oils: arachide (peanut) corn, safflower, linen, hempen, sesame, pumpkin seeds, grape seeds---values from 0.10 to 1.44 microg/kg and 3.83 microg/kg in sea buckthorn oil were detected. B(a)P concentration in 4 from 40 investigated oils exceed the 2 ppb limit proposed by the European Commission. Heating of sample of oils: olive, rape, soya, linen, corn, sesame, peanut, in temp. 240 degrees C for 30 min. has not influence on decreased of B(a)P level. PMID:18807910

  20. Ruthenium(salen)-catalyzed aerobic oxidative desymmetrization of meso-diols and its kinetics.

    Science.gov (United States)

    Shimizu, Hideki; Onitsuka, Satoaki; Egami, Hiromichi; Katsuki, Tsutomu

    2005-04-20

    Chiral (nitrosyl)ruthenium(salen) complexes were found to be efficient catalysts for aerobic oxidative desymmetrization of meso-diols under photoirradiation to give optically active lactols. The scope of the applicability of this reaction ranges widely from acyclic diols to mono-cyclic diols, although fine ligand-tuning of the ruthenium(salen) complexes was required to attain high enantioselectivity (up to 93% ee). In particular, the nature of the apical ligand was found to affect not only enantioselectivity but also kinetics of the desymmetrization reaction. Spectroscopic analysis of the oxidation disclosed that irradiation of visible light is indispensable not only for dissociation of the nitrosyl ligand but also for single electron transfer from the alcohol-bound ruthenium ion to dioxygen. PMID:15826178

  1. An ab initio study of three (ethane-1,2 diol/water) complexes

    Science.gov (United States)

    Manivet, Philippe; Masella, Michel

    1998-05-01

    Three (ethane-1,2 diol/water) complexes have been studied using ab initio calculations at the MP2 level. In two complexes, the ethane-1,2 diol structure is close to its gas phase experimental structure (presence of an intramolecular hydrogen bond HB and the O-C-C-O dihedral angle is gauche) while the intramolecular HB is disrupted by the presence of a water molecule in the third ( tGg'a). Computations have shown that most of the experimental observations regarding the solvation of ethane-1,2 diol in water may be reproduced only by considering the tGg'a complex (absence of intramolecular HB, O-C-C-O dihedral angle of 72-74°), which is also more stable than the other two by 2 kcal mol -1.

  2. Effect of strand-specific excision repair on the spectra of mutations induced by benzo[a]pyrene-diol epoxide and ultraviolet radiation in diploid human cells

    International Nuclear Information System (INIS)

    To study the effect of excision repair on the spectra of mutations induced in diploid human cells by UV and ±-7β, 8α-dihydroxy-9α,10α-epoxy- 7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), the author synchronized repair-proficient cells, treated them at the beginning of S phase or in G1 phase several hours prior to the onset of S phase, selected for thioguanine resistant cells, and determined the spectra of mutations in the coding region of the hyproxanthine(guanine)phosphoribosyl-transferase (HPRT) gene in the mutants. As a control, the spectra of mutations similarly induced in repair-deficient xeroderma pigmentosum (XP) cells were compared. There was no difference in the kinds of mutations observed in mutants derived from either cell strain treated with a particular mutagen either in S or in G1. With BPDE, the majority were G.C→T.A transversions; with UV, they were mainly G.C.→A.T transitions. The strand distribution of premutagenic lesions in mutants from repair-proficient cells treated in S or G1 differed significantly. The results strongly support the hypothesis that human cells preferentially repair UV- and BPDE-induced lesions from the transcribed strand of the HPRT gene. To test this, the rate of repair of BPDE adducts from individual strands of the HPRT gene was measured, using the UvrABC exinuclease and Southern hybridizations with strand-specific probes to detect lesions remaining. BPDE lesions were removed from the transcribed strand at a significantly faster rate than from the nontranscribed strand, consistent with my hypothesis. It was found that BPDE adducts were removed faster from either strand of the HPRT gene than from a transcriptionally inactive locus, indicating preferential repair of active genes. The results of these studies provide biochemical and biological evidence of strand-specific DNA repair of BPDE adducts in human cells

  3. Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols.

    Science.gov (United States)

    Couturier, Jean-Philippe; Wischerhoff, Erik; Bernin, Robert; Hettrich, Cornelia; Koetz, Joachim; Sütterlin, Martin; Tiersch, Brigitte; Laschewsky, André

    2016-05-01

    Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers' cloud point, or the induced changes of the hydrogels' swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye. PMID:27108735

  4. Crystallization and glass transition of the diols and aminoalcohols, according to DSC data

    Science.gov (United States)

    Solonina, I. A.; Rodnikova, M. N.; Kiselev, M. P.; Khoroshilov, A. V.

    2015-05-01

    Overcooling, crystallization, and glass transition of the diol series and aminoalcohols which are the liquids with spatial hydrogen-bond networks, which are the along with the overcooling of dioxane, dimethylsulfoxide, and acetonitrile, which do not have such networks were studied by DSC. The observed phenomena are explained by the stability of H-bond networks. It was concluded that changes in the stability of the networks in and between series of diols and aminoalcohols are due to differences between their molecular structures, the energies of their hydrogen bonds, and their network topologies.

  5. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    International Nuclear Information System (INIS)

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO4) salt and titanium dioxide (TiO2) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO4 causes a greater increase in glass transition temperature (Tg) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO2 in ENR/LiClO4 system, a remarkable Tg elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO2 loading where ENR25 shows enhancement of conductivity while ENR50 shows declination

  6. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    Science.gov (United States)

    Harun, Fatin; Chan, Chin Han; Sim, Lai Har; Winie, Tan; Zainal, Nurul Fatahah Asyqin

    2015-08-01

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO4) salt and titanium dioxide (TiO2) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO4 causes a greater increase in glass transition temperature (Tg) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO2 in ENR/LiClO4 system, a remarkable Tg elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO2 loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  7. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Harun, Fatin; Chan, Chin Han; Winie, Tan [Faculty of Applied Sciences, UniversitiTeknologi MARA (UiTM), Shah Alam, 40450 Selangor Darul Ehsan (Malaysia); Sim, Lai Har; Zainal, Nurul Fatahah Asyqin [Center of Foundation Studies, PuncakAlam Campus, UniversitiTeknologi MARA, 40430 Selangor Darul Ehsan (Malaysia)

    2015-08-28

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO{sub 4}) salt and titanium dioxide (TiO{sub 2}) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO{sub 4} causes a greater increase in glass transition temperature (T{sub g}) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO{sub 2} in ENR/LiClO{sub 4} system, a remarkable T{sub g} elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO{sub 2} loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  8. Kinetics of phosphotungstic acid catalyzed oxidation of propan-1,3-diol and butan-1,4-diol by N-chlorosaccharin

    Directory of Open Access Journals (Sweden)

    Sanjay Kumar Singh

    2011-09-01

    Full Text Available The kinetic studies of N-chlorosaccharin (NCSA oxidation of propan-1,3-diol and butan-1,4-diol have been reported in presence of phophotungstic acid and in aqueous acetic acid medium. The reactions follow first-order in NCSA and one to zero order with respect to substrate and phosphotungstic acid. Increase in the concentration of added perchloric acid increases the rate of oxidation. A negative effect on the oxidation rate is observed for solvent whereas the ionic strength does not influence the rate of reaction. Addition of the reaction product, saccharin, exhibited retarding effect. Various activation parameters have been evaluated. The products of the reactions were identified as the corresponding aldehydes. A suitable scheme of mechanism consistent with the experimental results has been proposed.

  9. Topological, functional, and dynamic properties of the protein interaction networks rewired by benzo(a)pyrene

    Energy Technology Data Exchange (ETDEWEB)

    Ba, Qian [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); Li, Junyang; Huang, Chao [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Li, Jingquan; Chu, Ruiai [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); Wu, Yongning, E-mail: wuyongning@cfsa.net.cn [Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); Wang, Hui, E-mail: huiwang@sibs.ac.cn [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); School of Life Science and Technology, ShanghaiTech University, Shanghai (China)

    2015-03-01

    Benzo(a)pyrene is a common environmental and foodborne pollutant that has been identified as a human carcinogen. Although the carcinogenicity of benzo(a)pyrene has been extensively reported, its precise molecular mechanisms and the influence on system-level protein networks are not well understood. To investigate the system-level influence of benzo(a)pyrene on protein interactions and regulatory networks, a benzo(a)pyrene-rewired protein interaction network was constructed based on 769 key proteins derived from more than 500 literature reports. The protein interaction network rewired by benzo(a)pyrene was a scale-free, highly-connected biological system. Ten modules were identified, and 25 signaling pathways were enriched, most of which belong to the human diseases category, especially cancer and infectious disease. In addition, two lung-specific and two liver-specific pathways were identified. Three pathways were specific in short and medium-term networks (< 48 h), and five pathways were enriched only in the medium-term network (6 h–48 h). Finally, the expression of linker genes in the network was validated by Western blotting. These findings establish the overall, tissue- and time-specific benzo(a)pyrene-rewired protein interaction networks and provide insights into the biological effects and molecular mechanisms of action of benzo(a)pyrene. - Highlights: • Benzo(a)pyrene induced scale-free, highly-connected protein interaction networks. • 25 signaling pathways were enriched through modular analysis. • Tissue- and time-specific pathways were identified.

  10. Topological, functional, and dynamic properties of the protein interaction networks rewired by benzo(a)pyrene

    International Nuclear Information System (INIS)

    Benzo(a)pyrene is a common environmental and foodborne pollutant that has been identified as a human carcinogen. Although the carcinogenicity of benzo(a)pyrene has been extensively reported, its precise molecular mechanisms and the influence on system-level protein networks are not well understood. To investigate the system-level influence of benzo(a)pyrene on protein interactions and regulatory networks, a benzo(a)pyrene-rewired protein interaction network was constructed based on 769 key proteins derived from more than 500 literature reports. The protein interaction network rewired by benzo(a)pyrene was a scale-free, highly-connected biological system. Ten modules were identified, and 25 signaling pathways were enriched, most of which belong to the human diseases category, especially cancer and infectious disease. In addition, two lung-specific and two liver-specific pathways were identified. Three pathways were specific in short and medium-term networks (< 48 h), and five pathways were enriched only in the medium-term network (6 h–48 h). Finally, the expression of linker genes in the network was validated by Western blotting. These findings establish the overall, tissue- and time-specific benzo(a)pyrene-rewired protein interaction networks and provide insights into the biological effects and molecular mechanisms of action of benzo(a)pyrene. - Highlights: • Benzo(a)pyrene induced scale-free, highly-connected protein interaction networks. • 25 signaling pathways were enriched through modular analysis. • Tissue- and time-specific pathways were identified

  11. Ovarian expressed microsomal epoxide hydrolase: Role in detoxification of 4-vinylcyclohexene diepoxide and regulation by phosphatidylinositol-3 kinase signaling

    International Nuclear Information System (INIS)

    4-vinylcyclohexene diepoxide (VCD) is a metabolite of 4-vinylcyclohexene (VCH) which has the potential to be formed in the ovary through CYP2E1 activity. VCD specifically destroys primordial and small primary follicles in the rodent ovary. Mouse ovaries exposed to VCD demonstrate increased mRNA and protein expression of microsomal epoxide hydrolase (mEH), and an inactive tetrol metabolite (4-(1,2-dihydroxy)ethyl-1,2-dihydroxycyclohexane) can be formed in mouse ovarian follicles, potentially through detoxification action of mEH. In contrast, mEH can bioactivate another ovotoxic chemical, 7,12-dimethylbenz[a]anthracene (DMBA) to a more toxic compound, DMBA-3,4-diol-1,2-epoxide. Thus, the present study evaluated a functional role for mEH during detoxification of VCD. Additionally, because inhibition of the phosphatidyinositol-3 kinase (PI3K) signaling pathway in a previous study protected primordial follicles from VCD-induced destruction, but accelerated DMBA-induced ovotoxicity, a role for PI3K in ovarian mEH regulation was evaluated. Using a post-natal day (PND) 4 Fischer 344 rat whole ovary culture system inhibition of mEH using cyclohexene oxide during VCD exposure resulted in a greater (P < 0.05) loss of primordial and small primary follicles relative to VCD-treated ovaries. Also, relative to controls, meh mRNA was increased (P < 0.05) on day 4 of VCD (30 μM) exposure, followed by increased (P < 0.05) mEH protein after 6 days. Furthermore, inhibition of PI3K signaling increased mEH mRNA and protein expression. Thus, these results support a functional role for mEH in the rat ovary, and demonstrate the involvement of PI3K signaling in regulation of ovarian xenobiotic metabolism by mEH. -- Highlights: ► Ovarian mEH functions to metabolize VCD to a less toxic compound. ► mEH expression is increased in a temporal pattern in response to VCD exposure. ► PI3K signaling is involved in regulation of ovarian mEH expression.

  12. Hepatitis B spliced protein (HBSP) promotes the carcinogenic effects of benzo [alpha] pyrene by interacting with microsomal epoxide hydrolase and enhancing its hydrolysis activity

    International Nuclear Information System (INIS)

    The risk of hepatocellular carcinoma (HCC) increases in chronic hepatitis B surface antigen (HBsAg) carriers who often have concomitant increase in the levels of benzo[alpha]pyrene-7,8-diol-9,10-epoxide(±) (BPDE)-DNA adduct in liver tissues, suggesting a possible co-carcinogenesis of Hepatitis B virus (HBV) and benzo[alpha]pyrene in HCC; however the exact mechanisms involved are unclear. The interaction between hepatitis B spliced protein (HBSP) and microsomal epoxide hydrolase (mEH) was confirmed using GST pull-down, co-immunoprecipitation and mammalian two-hybrid assay; the effects of HBSP on mEH-mediated B[alpha]P metabolism was examined by high performance liquid chromatography (HPLC); and the influences of HBSP on B[alpha]P carcinogenicity were evaluated by bromodeoxyuridine cell proliferation, anchorage-independent growth and tumor xenograft. HBSP could interact with mEH in vitro and in vivo, and this interaction was mediated by the N terminal 47 amino acid residues of HBSP. HBSP could greatly enhance the hydrolysis activity of mEH in cell-free mouse liver microsomes, thus accelerating the metabolism of benzo[alpha]pyrene to produce more ultimate carcinnogen, BPDE, and this effect of HBSP requires the intact HBSP molecule. Expression of HBSP significantly increased the formation of BPDE-DNA adduct in benzo[alpha]pyrene-treated Huh-7 hepatoma cells, and this enhancement was blocked by knockdown of mEH. HBSP could enhance the cell proliferation, accelerate the G1/S transition, and promote cell transformation and tumorigenesis of B[alpha]P-treated Huh-7 hepatoma cells. Our results demonstrated that HBSP could promote carcinogenic effects of B[alpha]P by interacting with mEH and enhancing its hydrolysis activity

  13. Chemical consequences of long-range orbital interaction in perhydronaphtalene-1,4 diol monosulfonate esters.

    NARCIS (Netherlands)

    Orru, R.V.A.

    1994-01-01

    In this thesis the base-induced reactions of perhydronaphthalene-1,4-diol monosulfonate esters are described. These compounds undergo smoothly, typical carbocationic processes upon treatment with sodium tert -amylate in refluxing benzene. The product outcome, product ratio, and (relative) rate of th

  14. Iridium‐Catalyzed Condensation of Amines and Vicinal Diols to Substituted Piperazines

    DEFF Research Database (Denmark)

    Lorentz-Petersen, Linda Luise Reeh; Nordstrøm, Lars Ulrik Rubæk; Madsen, Robert

    2012-01-01

    is believed to involve dehydrogenation of the 1,2‐diol to the α‐hydroxy aldehyde, which condenses with the amine to form the α‐hydroxy imine. The latter rearranges to the corresponding α‐amino carbonyl compound, which then reacts with another amine followed by reduction of the resulting imine....

  15. In Situ Spectroscopic Investigation of the Rhenium-Catalyzed Deoxydehydration of Vicinal Diols

    DEFF Research Database (Denmark)

    Dethlefsen, Johannes Rytter; Fristrup, Peter

    2015-01-01

    rhenium(V) complex (the rate-limiting step), 2) condensation of the diol and the rhenium(V) complex to a rhenium(V) diolate, and 3) extrusion of the alkene accompanied by oxidation of the Re center and thus regeneration of CH3ReO3. The reaction follows zero-order kinetics initially but, unexpectedly...

  16. 211At-Rh(16-S4-diol) complex as a precursor for astatine radiopharmaceuticals

    International Nuclear Information System (INIS)

    211At is one of the most promising radionuclides in α-radioimmunotherapy (α-RIT). Unfortunately, biomolecules labeled by direct electrophilic astatination are unstable due to the rapid loss of 211At under both in vitro and in vivo conditions. The present paper describes the results of our studies on attaching At- to the rhodium(III) complex with thioether ligand: 1,5,9,13-etrathiacyclohexadecane-3,11-diol (16-S4-diol). Rh3+ was chosen as a moderately soft metal cation which should form very strong bonds with soft At- anions, but first of all because of the kinetic inertness of low spin rhodium(III) d6 complexes. The 16-S4-diol ligand was selected due to formation of stable complexes with Rh3+. The experiments related to optimization of the reaction conditions were performed with the 131I, basing on a chemical similarity of I- to At-. The experiments with 211At were then carried out under the conditions found optimal for I-. The preliminary results are promising, and indicate a possibility for astatination of biomolecules by using the 211At-Rh(16-S4-diol) complex

  17. An efficient hydrophilic interaction liquid chromatography separation of 7 phospholipid classes based on a diol column

    NARCIS (Netherlands)

    Zhu, C.; Dane, A.; Spijksma, G.; Wang, M.; Greef, J. van der; Luo, G.; Hankemeier, T.; Vreeken, R.J.

    2012-01-01

    A hydrophilic interaction liquid chromatography (HILIC) - ion trap mass spectrometry method was developed for separation of a wide range of phospholipids. A diol column which is often used with normal phase chromatography was adapted to separate different phospholipid classes in HILIC mode using a m

  18. Isocyanate Reduction by Epoxide Substitution of Alcohols for Polyurethane Bioelastomer Synthesis

    Directory of Open Access Journals (Sweden)

    Arnold A. Lubguban

    2011-01-01

    Full Text Available A phosphate ester-forming reaction was carried out by mixing epoxidized soybean oil with up to 1.5% o-phosphoric acid. In situ oligomerization took effect almost instantly producing a clear, homogeneous, highly viscous, and a low-acid product with a high average functionality. The resulting epoxide was used as a reactant for urethane bioelastomer synthesis and evaluated for rigid foam formulation. Results have shown that with a number of catalysts tested phosphoric acid significantly enhances a solvent-free oxirane ring cleavage and polymerization of the epoxidized soybean oil via phosphate-ester formation at room temperature. The resulting phosphoric acid-catalyzed epoxide-based bioelastomer showed an 80% decrease in extractable content and increased tensile strength at the same isocyanate loading relative to the noncatalyzed epoxide. The oligomerized epoxidized soybean oil materials exhibited ASTM hydroxyl values 40% less than the nonoligomerized starting material which translates to reduced isocyanate loadings in urethane applications.

  19. Inhibition of aryl hydrocarbon receptor transactivation and DNA adduct formation by CYP1 isoform-selective metabolic deactivation of benzo[a]pyrene

    International Nuclear Information System (INIS)

    Benzo[a]pyrene (BaP), a polyaromatic hydrocarbon produced by the combustion of cigarettes and coke ovens, is a known procarcinogen. BaP activates the aryl hydrocarbon receptor (AhR) and induces the expression of a battery of genes, including CYP1A1, which metabolize BaP to toxic compounds. The possible role of CYP1 enzymes in mediating BaP detoxification or metabolic activation remains to be elucidated. In this study, we assessed the effects of CYP1 enzymes (CYP1A1, CYP1A2 and CYP1B1) on BaP-induced AhR transactivation and DNA adduct formation in HEK293 cells and HepG2 cells. Transfection of CYP1A1 and CYP1B1, but not CYP1A2, suppressed BaP-induced activation of AhR. Expression of CYP1A1 and CYP1A2, but not CYP1B1, inhibited DNA adduct formation in BaP-treated HepG2 cells. These results indicate that CYP1A1 and CYP1B1 play a role in deactivation of BaP on AhR and that CYP1A1 and CYP1A2 are involved in BaP detoxification by suppressing DNA adduct formation. BaP treatment did not induce DNA adduct formation in HEK293 cells, even after transfection of CYP1 enzymes, suggesting that expression of CYP1 enzymes is not sufficient for DNA adduct formation. Lower expression of epoxide hydrolase and higher expression of glutathione S-transferase P1 (GSTP1) and GSTM1/M2 were observed in HEK293 cells compared with HepG2 cells. Dynamic expression of CYP1A1, CYP1A2 and CYP1B1 along with expression of other enzymes such as epoxide hydrolase and phase II enzymes may determine the detoxification or metabolic activation of BaP

  20. Preparation of soluble molybdenum catalysts for epoxidation of olefins

    International Nuclear Information System (INIS)

    This patent describes the process of regenerating a soluble molybdenum composition to obtain a stable catalyst solution capable of being employed as a catalyst in the process for the epoxidation of an olefin with an organic hydroperoxide. Thermally precipitating and separating a molybdenum-containing solid contains up to about 50 percent by weight, of molybdenum from a spent catalyst solution derived from a molybdenum-catalyzed olefin epoxidation reaction. The molybdenum-containing solid has been contained by heating the spent catalyst solution with either solid solubilizating. The separated precipitated solid forms a soluble molybdenum composition by contacting at a temperature of between about 200C and about 1300C, and removing any undesired solid material remaining with the solubilized molybdenum composition

  1. Kinetics and mechanism of the oxidation of some vicinal and non-vicinal diols by tetrabutylammonium tribromide

    Indian Academy of Sciences (India)

    Jaya Gosain; Pradeep K Sharma

    2003-04-01

    Kinetics of oxidation of five vicinal and four non-vicinal diols, and two of their monoethers, by tetrabutylammonium tribromide (TBATB) has been studied. The vicinal diols yield products arising out of glycol-bond fission, while the non-vicinal diols produce the hydroxycarbonyl compounds. The reaction is first-order with respect to TBATB. Michaelis-Menten type kinetics is observed with respect to diols. The reaction fails to induce the polymerization of acrylonitrile. There is no effect of tetrabutylammonium chloride on the reaction rate. The proposed reactive oxidizing species is the tribromide ion. The effect of solvent composition indicates that the rate increases with increase in the polarity of the solvent. The oxidation of [1,1,2,2-2H4] ethanediol shows the absence of any primary kinetic isotope effect. Values of solvent isotope effect, (H2O)/(D2O), at 288 K for the oxidation of ethanediol, propane-1,3-diol and 3-methoxybutan-1-ol are 3.41, 0.98 and 1.02 respectively. A mechanism involving a glycol-bond fission has been proposed for the oxidation of vicinal diols. Non-vicinal diols are oxidised by a hydride-transfer mechanism, as they are monohydric alcohols.

  2. Some novel aspects of carbocation chemistry via sn1 ring opening of epoxides.

    OpenAIRE

    Herbal, K.

    2005-01-01

    This thesis concentrates on the study of the SnI like ring opening of epoxides, and in particular, it focuses on the formation of ally lie alcohols and a,/-unsaturated ketones from epoxides. The work is described in the three main chapters of this thesis. An introductory chapter reviews the target natural product, I-carvone, and its industrial applications. There is a comprehensive review of the existing preparative methods of allylic alcohols from epoxides, with detailed discussion of the ty...

  3. Direct epoxidation of propylene over stabilized Cu(+) surface sites on titanium-modified Cu2O.

    Science.gov (United States)

    Yang, Xiaofang; Kattel, Shyam; Xiong, Ke; Mudiyanselage, Kumudu; Rykov, Sergei; Senanayake, Sanjaya D; Rodriguez, José A; Liu, Ping; Stacchiola, Dario J; Chen, Jingguang G

    2015-10-01

    Direct propylene epoxidation by O2 is a challenging reaction because of the strong tendency for complete combustion. Results from the current study demonstrate that by generating highly dispersed and stabilized Cu(+) active sites in a TiCuOx mixed oxide the epoxidation selectivity can be tuned. The TiCuOx surface anchors the key surface intermediate, an oxametallacycle, leading to higher selectivity for epoxidation of propylene. PMID:26215635

  4. Effect of ionizing radiation on the structure and epoxide composition properties

    International Nuclear Information System (INIS)

    The effect of ionizing radiation on the epoxide composition structure and properties is investigated. It is shown, that epoxide composition radiation resistance is determined not only by the chemical nature of the components, but by their hardening regime as well. Moreover, even very low dose irradiation of epoxide compositions changes sufficiently their adhesion to the substrate surface. Properties of composites in the initial state improve and their radiation resistance increases with introduction of elastifying additions

  5. Markedly Elevated Carbamazepine-10,11-epoxide/Carbamazepine Ratio in a Fatal Carbamazepine Ingestion

    OpenAIRE

    Russell, Jason L.; Spiller, Henry A.; Baker, Daniel D.

    2015-01-01

    Carbamazepine is a widely used anticonvulsant. Its metabolite, carbamazepine-10,11-epoxide, has been found to display similar anticonvulsant and neurotoxic properties. While the ratio of parent to metabolite concentration varies significantly, at therapeutic doses the epoxide concentration is generally about 20% of the parent. We report a case of fatal carbamazepine overdose in which the epoxide metabolite concentration was found to be 450% higher than the parent compound, suggesting a potent...

  6. Nickel-Catalyzed Regiodivergent Opening of Epoxides with Aryl Halides: Co-Catalysis Controls Regioselectivity

    OpenAIRE

    Zhao, Yang; Weix, Daniel J.

    2013-01-01

    Epoxides are versatile intermediates in organic synthesis, but have rarely been employed in cross-coupling reactions. We report that bipyridine-ligated nickel can mediate the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the co-catalyst employed. Iodide co-catalysis results in opening at the less hindered position via an iodohydrin intermediate. Titan...

  7. Intercalation of quaternary ammonium epoxide into montmorillonite structure

    Czech Academy of Sciences Publication Activity Database

    Duchek, P.; Špírková, Milena; Šabata, Stanislav

    Beijing : Chinese Vacuum Society, 2010. s. 109. [International Vacuum Congress /18./, International Conference on Nanoscience and Technology, International Conference on Solid Surfaces /14./, Vacuum and Surface Sciences Conference of Asia and Australia. 23.08.2010-27.08.2010, Beijing] R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40720504 Keywords : montmorillonite * quaternary ammonium epoxide * intercalation Subject RIV: JI - Composite Materials

  8. Catalysts for CO2/epoxide ring-opening copolymerization

    OpenAIRE

    G. Trott; Saini, P. K.; Williams, C. K.

    2016-01-01

    This article summarizes and reviews recent progress in the development of catalysts for the ring-opening copolymerization of carbon dioxide and epoxides. The copolymerization is an interesting method to add value to carbon dioxide, including from waste sources, and to reduce pollution associated with commodity polymer manufacture. The selection of the catalyst is of critical importance to control the composition, properties and applications of the resultant polymers. This review highlights an...

  9. Acid-Catalyzed Reaction of Epoxides on Atmospheric Nanoparticles

    Science.gov (United States)

    Xu, W.; Gomez-Hernandez, M.; Lal, V.; Qiu, C.; Khalizov, A. F.; Wang, L.; Zhang, R.

    2013-12-01

    Aerosol plays an important role in affecting the earth climate and harming human health. Atmospheric aerosols can be formed from either primary emissions or gas-to-particle conversion process. Numerous studies, including both experimental and theoretical, have been carried out to elucidate the mechanism of gas-to-particle conversion process (a.k.a. nucleation) and the later growth stage of newly formed nanoparticles. However, a complete list of species involving in the nucleation and growth processes of nanoparticles is still poorly understood. The growth of newly formed sulfuric acid - water nanoparticles has been suggested to involve several potential organic vapors, such as amines, glyoxal, 2-4 hexadienal, and epoxides. In the present study, new formed sulfuric acid -water nanoparticles were size selected by a differential mobility analyzer and exposed to epoxide vapors. The size-change after exposure was detected using the second differential mobility analyzer. The size-enlarged particles were then collected by an electrostatic precipitator, thermal vaporized, and analyzed by an ion drift chemical ionization mass spectrometer. Our results show that the sizes of nanoparticles are increased considerably and the magnitude of the increment in size is size-dependent. Mass spectrometry analysis of the nanoparticles after exposure demonstrates that low volatile organosulfate and oligomers are formed in nanoparticles upon their exposure to epoxide vapors.

  10. Preliminary studies of epoxidized palm oil as sizing chemical for carbon fibers

    International Nuclear Information System (INIS)

    Epoxidized palm oil is derived from palm oil through chemical reaction with peracetic acid. Preliminary studies to coat carbon fibers have shown promising result towards applying natural product in carbon fibre composites. Mechanical studies of sized carbon fibers with epoxidized palm oil showed significant increase in tensile and interfacial shear strength. Surface morphology of sized or coated carbon fibers with epoxidized palm oil reveals clear increase in root means square-roughness (RMS). This indicates the change of the surface topography due to sized or coated carbon fibers with epoxidized palm oil. (author)

  11. Nickel-catalyzed regiodivergent opening of epoxides with aryl halides: co-catalysis controls regioselectivity.

    Science.gov (United States)

    Zhao, Yang; Weix, Daniel J

    2014-01-01

    Epoxides are versatile intermediates in organic synthesis, but have rarely been employed in cross-coupling reactions. We report that bipyridine-ligated nickel can mediate the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the cocatalyst employed. Iodide cocatalysis results in opening at the less hindered position via an iodohydrin intermediate. Titanocene cocatalysis results in opening at the more hindered position, presumably via Ti(III)-mediated radical generation. 1,2-Disubstituted epoxides are opened under both conditions to form predominantly the trans product. PMID:24341892

  12. Dietary effects on the uptake of benzo[a]pyrene.

    Science.gov (United States)

    Stavric, B; Klassen, R

    1994-08-01

    It has been established that exposure to polycyclic aromatic hydrocarbons (PAHs), or more specifically benzo[a]pyrene (B[a]P), either by inhalation through cigarette smoking or by contact through occupational exposure of the lungs or skin, can result in cancerous lesions. It appears that the general population consumes more B[a]P from food than from smoking. Despite this, epidemiological studies have not implicated B[a]P from foods as a causative factor in some human cancers. This lack of an epidemiological correlation between cancer incidence and intake of dietary PAHs/B[a]P could be due to some 'protective' or 'detoxification' mechanism. Despite the abundance of literature regarding the food content of B[a]P, there are few data concerning its uptake from foods. In the present study we investigated the intestinal absorption of B[a]P from foods using bile duct cannulated rats and radioactive B[a]P. [14C]B[a]P was first added to solvents such as water, corn oil, liquid paraffin or 50% ethanol, which were the administered by gavage to rats fed diets with or without added carbon. Additionally, food polyphenols such as quercetin and chlorogenic acid were also tested for their effect on the absorption of B[a]P. The results indicated that the excretion of B[a]P in the bile was reduced by water, carbon, quercetin and chlorogenic acid but was potentiated by corn oil. To complement the in vivo studies, some in vitro tests to investigate the efficiency of B[a]P extraction from different foods using water or oil as solvents were also performed. These tests indicated that extraction of B[a]P from foods was affected by the solvent. It is postulated that reduced solubility, physical adsorption and the formation of chemical adducts between B[a]P and some food ingredients, play a sporadic, although still not well determined, role in reducing the absorption of B[a]P from the gut. The results of these studies suggest that B[a]P absorption from the intestinal tract is markedly

  13. Metabolic enzyme activities, metabolism-related genes expression and bioaccumulation in juvenile white shrimp Litopenaeus vannamei exposed to benzo[a]pyrene.

    Science.gov (United States)

    Ren, Xianyun; Pan, Luqing; Wang, Lin

    2014-06-01

    The purpose of this study was to investigate the impact of benzo[a]pyrene (BaP) on metabolic detoxification system and bioaccumulation of white shrimp Litopenaeus vannamei. In this study, juvenile white shrimp L. vannamei were exposed for 21 days at four different concentrations of 0, 0.03, 0.3 and 3μg/L. Detoxification enzyme activities of phase I (aryl hydrocarbon hydroxylase (AHH), 7-ethoxyresorufin O-deethylase (EROD), epoxide hydrolase (EH)) and phase II (glutathione-S-transferase (GST), sulfotransferase (SULT), uridine diphosphate glucuronyl transferase (UGT)) were determined, and results showed that all the detoxification enzyme activities increased in a dose-dependent manner except for the low BaP exposure. Transcription of genes was detected and measured by real-time RT-PCR. It showed that at day six BaP increased cytochrome P450 (CYP) 1A1, GST, SULT visa aryl hydrocarbon receptor (AhR) mRNA expression in a dose-dependent manner, which suggests that they could be potential targets of BaP that disrupt the detoxification system. The consistency of their responses to BaP exposure implies that AhR action may be involved in invertebrate CYP regulation. Additionally, BaP bioaccumulation increased rapidly first and showed an incoming plateau. Besides, the enzyme activities and bioaccumulation in the hepatopancreas were higher than those in the gills. These results will not only provide information on BaP metabolic mechanism for this species, but also scientific data for pollution monitoring. PMID:24636950

  14. Mechanism-based inactivation of benzo[a]pyrene hydroxylase by aryl acetylenes and aryl olefins

    International Nuclear Information System (INIS)

    A series of aryl acetylenes and aryl olefins have been examined as substrates and inhibitors of cytochrome P-450 dependent monooxgenases in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene, 3-ethynylperylene, 2-ethynylfluorene, methyl 1-pyrenyl acetylene, cis- and trans-1-(2-bromovinyl)pyrene, and 1-allylpyrene serve as mechanism-based irreversible inactivators (suicide inhibitors) of benzo[a]pyrene hydroxylase, while 1-vinylpyrene and phenyl 1-pyrenyl acetylene do not cause a detectable suicide inhibition of benzo[a]pyrene hydroxylase. The mechanism-based loss of benzo[a]pyrene hydroxylase caused by the aryl acetylenes is not accompanied by a corresponding loss of the P-450 content of the microsomes (suicide destruction). The suicide inhibition by these aryl acetylenes therefore does not involve covalent binding to the heme moiety of the monooxygenase. Nevertheless, in the presence of NADPH, 3H-labeled 1-ethynylpyrene becomes covalently attached to the cytochrome P-450 protein; the measured stoichiometry of binding is one 1-ethynylpyrene per P-450 heme unit. The authors conclude that the inhibition of benzo[a]pyrene hydroxylase produced by 1-ethynylpyrene may be related to the mechanism of suicide inhibition of P-450 activity by chloramphenicol rather than the mechanism of suicide destruction of P-450 previously described for acetylene and propyne

  15. The mixed diol-dithiol 2,2-bis(sulfanylmethyl)propane-1,3-diol: characterization of key intermediates on a new synthetic pathway.

    Science.gov (United States)

    Simmons, Trevor R; Pickett, Christopher J; Wright, Joseph A

    2011-01-01

    A new synthetic route to 2,2-bis(sulfanylmethyl)propane-1,3-diol, (II), is described starting from the commercially available 2,2-bis(hydroxymethyl)propane-1,3-diol. The structures of two intermediates on this route are described. 5,5-Dimethenyl-2,2-dimethyl-1,3-dioxane bis(thiocyanate) (systematic name: {[5-(cyanosulfanyl)-2,2-dimethyl-1,3-dioxan-5-yl]sulfanyl}formonitrile), C(10)H(14)N(2)O(2)S(2), (X), crystallizes in the space group P2(1)/c with no symmetry relationship between the two thiocyanate groups. There is a short intramolecular N...S contact for one thiocyanate group, while the second group is positioned such that this type of interaction is not possible. 1,3-(Hydroxymethyl)propane-1,3-diyl bis(thiocyanate), C(7)H(10)N(2)O(2)S(2), (XI), also features a single short N···S contact in the solid state. Hydrogen bonding between two molecules of compound (XI) results in the formation of dimers in the crystal, which are then linked together by a second hydrogen-bond interaction between the dimers. In addition, the structures of two intermediates from an unsuccessful alternative synthesis of (II) are reported. 2,2-Bis(chloromethyl)propane-1,3-diol, C(5)H(10)Cl(2)O(2), (VI), crystallized as an inversion twin with a minor twin fraction of 0.43 (6). It forms a zigzag structure as a result of intermolecular hydrogen bonding. The structure of 9,9-dimethyl-2,4,8,10-tetraoxa-3λ(4)-thiaspiro[5.5]undecan-3-one, C(8)H(14)O(5)S, (VII), shows evidence for a weak S···O contact with a distance of 3.2529 (11) Å. PMID:21206075

  16. Cultured mouse embryos metabolize benzo[a]pyrene during early gestation: genetic differences detectable by sister chromatid exchange.

    OpenAIRE

    Galloway, S M; Perry, P E; Meneses, J. (Julio); Nebert, D W; Pedersen, R A

    1980-01-01

    Mouse embryos explanted at 7 1/2 or 8 1/2 days of gestation were cultured in medium containing benzo[a]pyrene and supplemented with 5-bromodeoxyuridine to allow detection of sister chromatid exchanges. The murine Ah locus regulates the inducible metabolism of polycyclic hydrocarbons such as benzo[a]pyrene. A high frequency of sister chromatid exchange was induced by benzo[a]pyrene in embryos from three Ah-"responsive" inbred strains (BALB/cDub, C3H/AnfCum, and C57BL/6N); there was little or n...

  17. Characterization of three protein components required for functional reconstitution of the epoxide carboxylase multienzyme complex from Xanthobacter strain Py2.

    OpenAIRE

    Allen, J. R.; Ensign, S A

    1997-01-01

    Epoxide carboxylase from Xanthobacter strain Py2 catalyzes the reductant- and NAD+-dependent carboxylation of aliphatic epoxides to beta-keto acids. Epoxide carboxylase from Xanthobacter strain Py2 has been resolved from cell extracts by anion-exchange chromatography into three protein components, designated I, II, and III, that are obligately required for functional reconstitution of epoxide carboxylase activity. Component II has been purified to homogeneity on the basis of its ability to co...

  18. Asymmetric reduction of α-hydroxy aromatic ketones to chiral aryl vicinal diols using carrot enzymes system

    Institute of Scientific and Technical Information of China (English)

    Xiang Liu; Yi Wang; Hai Yan Gao; Jian He Xu

    2012-01-01

    Asymmetric reduction of α-hydroxy aromatic ketones was carried out by using carrot enzymes system,yielding corresponding chiral vicinal diols with special functional groups.The optimum reaction conditions were obtained after investigation of various influencing factors.Chiral aryl vicinal diols were produced with good yields and excellent enantiomeric excesses under appropriate conditions,Meanwhile,the steric factors and electronic effects of the substituents on the aromatic ring were shown to have an interesting influence on both yield and enantioselectivity.

  19. Percutaneous absorption of an insect repellent p-menthane-3,8-DIOL: a model for human dermal absorption.

    Science.gov (United States)

    Reifenrath, William G; Olson, James J; Vedula, Usha; Osimitz, Thomas G

    2009-01-01

    p-Menthane-3,8-diol(38DIOL) was recently introduced as a natural topical insect repellent in the commercial product "OFF! Botanicals" lotion. The objective of this study was to provide an estimate of the potential for 38DIOL systemic absorption in humans. Carbon-14-labeled 38DIOL formulated in the lotion and in an ethanol solution was applied to excised pig skin in an in vitro flow-through test system predictive of skin absorption in humans. Twenty-four hours after application, radiolabel recovered from the dermis and receptor fluid was summed to determine percent absorption. At a dose of approximately 80 microg/cm(2) of 38DIOL in the lotion, a value of 3.5 +/- 0.8% of applied dose was obtained with pig skin. The corresponding value for 38DIOL in ethanol (90 microg/cm(2)) was not significantly different (3.0 +/- 1.2%). Most of the applied dose of 38DIOL was found to evaporate from pig skin (77 +/- 8% for the lotion and 87 +/- 1% for ethanol solution), thus limiting percutaneous absorption values. For reference purposes, the pig skin absorptions of piperonyl butoxide (PBO) at 100 microg/cm(2) in isopropanol, N,N-diethyl-m-toluamide (DEET) at 500 microg/cm(2) in ethanol, and neat isododecane at 650 microg/cm(2) (in order of increasing volatility) were 15 +/- 6%, 23 +/- 3%, and 0.09 +/- 0.05% of applied dose respectively. Isododecane was lost almost exclusively from the skin surface by evaporation. For additional reference, absorptions of PBO, DEET, and 38DIOL were found to be higher with excised rat skin. PMID:19557607

  20. Absolute Configuration Determination of Azulenyl Diols Isolated From Asymmetric Pinacol Coupling.

    Science.gov (United States)

    Dragu, Eugenia Andreea; Naubron, Jean-Valere; Hanganu, Anamaria; Razus, Alexandru C; Nica, Simona

    2015-11-01

    A convenient enantioselective approach for the pinacol coupling of 1-acetylazulene involving easily accessible (R)- or (S)-BINOLs as chiral additive is reported. This supposes the preformation of the chiral titanium-BINOL complex in 1:2 ratio and subsequent reduction with zinc when, 2,3-di(azulen-1-yl)butane-2,3-diol can be isolated in around 60% enantiomeric excess. The absolute configuration of the isolated enantiomers was assigned by comparison of the experimental and Boltzmann-weighted calculated VCD and ECD spectra and assigned as (+)-(2S;3S)-di(azulen-1-yl)butane-2,3-diol. Chirality 27:826-834, 2015. © 2015 Wiley Periodicals, Inc. PMID:26364568

  1. Copper-catalyzed cross-coupling reactions of epoxides with gem-diborylmethane: access to γ-hydroxyl boronic esters.

    Science.gov (United States)

    Ebrahim-Alkhalil, Ahmed; Zhang, Zhen-Qi; Gong, Tian-Jun; Su, Wei; Lu, Xiao-Yu; Xiao, Bin; Fu, Yao

    2016-04-01

    Herein, we describe a novel copper-catalyzed epoxide opening reaction with gem-diborylmethane. Aliphatic, aromatic epoxides as well as aziridines are converted to the corresponding γ-pinacolboronate alcohols or amines in moderate to excellent yields. This new reaction provides beneficial applications for classic epoxide substrates as well as interesting gem-diborylalkane reagents. PMID:26973991

  2. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Science.gov (United States)

    2010-07-01

    ... alcohol, halogenated alkane, substituted epoxide, and amino compound (generic). 721.10145 Section 721... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... epoxide, and amino compound (PMN P-06-816) is subject to reporting under this section for the...

  3. Antibacterial action of 2-bromo-2-nitropropane-1,3-diol (bronopol).

    OpenAIRE

    Shepherd, J A; Waigh, R D; Gilbert, P

    1988-01-01

    Patterns of growth inhibition of Escherichia coli in the presence of 2-bromo-2-nitropropane-1,3-diol (bronopol) indicate a period of biocide-induced bacteriostasis followed by growth at an inhibited rate. The length of the bacteriostatic period, but not the subsequent growth inhibition, was reduced by the addition of excess cysteine. Patterns of growth inhibition were unaffected by catalase or superoxide dismutase. The bactericidal concentrations (100 to 500 micrograms/ml) were considerably i...

  4. Colloidal and Chemical Properties of Polyesters Based on Glutamic acid and Diols of Different Nature

    OpenAIRE

    Puzko N.V.; Varvarenko S.S.; Voronov A.S.; Dron I.A.; Tarnavchyk I.T.; Nosova N.G.; Samaryk V.J.; Voronov S.A.

    2012-01-01

    The paper describes synthesis method and colloid-chemical properties of novel α-amino acid based polyesters with controllable hydrophilic-lipophillic balance. Glutamic acid and diols of different nature based polyesters were obtained via low-temperature activated polyesterefication. Such polymers are able to form micellar structures in self-stabilized water dispersion. Solubilization of water insoluble dyes Sudan and toluene in polymer water solution was studied. Due to micelle forming abilit...

  5. Preparation for Supramolecular Complexes of Chiral Diols BDPDD, DMBDPD and BINOL with Some Prochiral Compounds

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Interaction between chiral diols BDPDD, DMBDPD and BINOL with prochiral compounds was examined and some new supramolecular complexes were prepared. It was found that these chiral hosts could include prochiral guests,α,β-unsaturated compounds or piper- azinedione derivatives to give inclusion crystals in different molar ratio. Formations of these supramolecular complexes were characterized by the data of IR and 1H NMR spectra.

  6. Synthesis and characterization of biodegradable materials: PDLLA-(MAh-Diol)n-PDLLA copolymer

    Institute of Scientific and Technical Information of China (English)

    Jia Chen; Yuan Liang Wang; Mei Na Huang

    2007-01-01

    The novel biodegradable copolymer PDLLA-(MAH-Diol)n-PDLLA with unsaturated bond was synthesized by copolymerizing lactide and prepolymer, which was prepared by the polycondensation of maleic anhydride and poly(ethylene glycol), using ptoluene sulphonic acid as catalyst. The new copolymer has improved hydrophilicity and flexibility. The structure and properties of the novel polymers were studied by FTIR, NMR, GPC-MALLS and DSC.

  7. Photoaffinity labeling of opioid receptor with morphine-7,8-oxide (morphine epoxide)

    Energy Technology Data Exchange (ETDEWEB)

    Takayanagi, I.; Shibata, R.; Miyata, N.; Hirobe, M.

    1982-05-01

    The opioid receptor mediating inhibitory action of morphine in the electrically stimulated guinea pig ileum was irreversibly photoinactivated by morphine epoxide (3 X 10(-6) M). Morphine epoxide (up to 3 X 10(-5) M) did not influence the responses of rat vas deferens (epsilon-receptor) or rabbit vas deferens (kappa-receptor) to electrical stimulation. Effective concentrations of morphine epoxide were much lower in the guinea pig ileum (mu-receptor) than in the mouse vas deference (delta-receptor). The inhibitory action of (Met)-enkephalin on the twitch responses of the rat vas deferens and mouse vas deferens to electrical stimulation were not influenced after irradiation in the presence of morphine epoxide (3 X 10(-6) M). Therefore, morphine epoxide is probably a useful probe for photoaffinity labeling of the mu-receptor in vitro.

  8. Photoaffinity labeling of opioid receptor with morphine-7,8-oxide (morphine epoxide)

    International Nuclear Information System (INIS)

    The opioid receptor mediating inhibitory action of morphine in the electrically stimulated guinea pig ileum was irreversibly photoinactivated by morphine epoxide (3 X 10(-6) M). Morphine epoxide (up to 3 X 10(-5) M) did not influence the responses of rat vas deferens (epsilon-receptor) or rabbit vas deferens (kappa-receptor) to electrical stimulation. Effective concentrations of morphine epoxide were much lower in the guinea pig ileum (mu-receptor) than in the mouse vas deference (delta-receptor). The inhibitory action of [Met]-enkephalin on the twitch responses of the rat vas deferens and mouse vas deferens to electrical stimulation were not influenced after irradiation in the presence of morphine epoxide (3 X 10(-6) M). Therefore, morphine epoxide is probably a useful probe for photoaffinity labeling of the mu-receptor in vitro

  9. Effect of epoxide equivalent on microstructure of epoxy/rectorite nanocomposite studied by positrons

    International Nuclear Information System (INIS)

    The epoxy/rectorite nanocomposites with different epoxide equivalent ranging from 188 to 1110 were prepared and the effects of epoxide equivalent on microstructure of materials were studied by X-ray diffraction (XRD) and positron annihilation lifetime spectroscope (PALS). In nanocomposites, the formation of exfoliated structure was observed from XRD pattern at epoxide equivalent >263. The PALS measurements reveal that the fractional free volume in nanocomposites was strongly affected by epoxide equivalent, in particular, the free-volume concentration was dramatically decreased with the increasing epoxide equivalent from 188 to 263, and the S parameter indicates the rectorite structure change and the high sensitivity of positron annihilation to the entry of rectorite into epoxy. These results indicate that positron annihilation characteristics are useful for study the microstructure of epoxy/rectorite nanocomposites

  10. Phosphotungstate-Based Ionic Silica Nanoparticles Network for Alkenes Epoxidation

    Directory of Open Access Journals (Sweden)

    Xiaoting Li

    2015-12-01

    Full Text Available An inorganic-organic porous silica network catalyst was prepared by linking silica nanoparticles using ionic liquid and followed by anion-exchange with phosphotungstate. Characterization methods of FT-IR, TG, SEM, TEM, BET, etc., were carried out to have a comprehensive insight into the catalyst. The catalyst was used for catalyzing cyclooctene epoxidation with high surface area, high catalytic activity, and convenient recovery. The conversion and selectivity of epoxy-cyclooctene could both reach over 99% at 70 °C for 8 h using hydrogen peroxide (H2O2 as an oxidant, and acetonitrile as a solvent when the catalyst was 10 wt. % of cyclooctene.

  11. Catalysts for CO2/epoxide ring-opening copolymerization.

    Science.gov (United States)

    Trott, G; Saini, P K; Williams, C K

    2016-02-28

    This article summarizes and reviews recent progress in the development of catalysts for the ring-opening copolymerization of carbon dioxide and epoxides. The copolymerization is an interesting method to add value to carbon dioxide, including from waste sources, and to reduce pollution associated with commodity polymer manufacture. The selection of the catalyst is of critical importance to control the composition, properties and applications of the resultant polymers. This review highlights and exemplifies some key recent findings and hypotheses, in particular using examples drawn from our own research. PMID:26755758

  12. Electroless copper coating of epoxide plates in an ultrasonic field.

    Science.gov (United States)

    Touyeras, F; Hihn, J Y; Doche, M L; Roizard, X

    2001-07-01

    This paper reports the study of ultrasonic irradiation effects on electroless copper coating on an epoxide resin. Several parameters were monitored, such as plating rates, practical adhesion and internal stress, versus varying acoustic powers at a constant frequency of 530 kHz. Exposure conditions were characterised by both transmitted power and interfacial mass transfer coefficients. Optimum conditions expressed in irradiation time and power were determined. The use of ultrasound during electroless copper plating affects the plating rates and the deposits properties, particularly the practical adhesion which increases whereas the internal stress decreases. Then, the changes in the coating mechanisms are discussed. PMID:11441612

  13. Lap test of epoxide resin at cryogenic temperatures

    International Nuclear Information System (INIS)

    Basic investigation is sought about the initiation of defects which may control magnet degradation. Clarification is sought concerning the problem of the stability of superconducting magnets. The race track coil test is described. A compression test of epoxide resins is presented in order to determine the mechanical properties of the basic material. A lap test is described which obtains basic information about the mechanical behaviour of the potting materials as the adhesive which fixes the wires to each other. Supplementary studies are referred to and conclusions drawn concerning stretch tests of potted coil and lap shear tests

  14. Electrochemical detection of benzo(a)pyrene and related DNA damage using DNA/hemin/nafion–graphene biosensor

    International Nuclear Information System (INIS)

    Graphical abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed to quantitatively study the DNA damage induced by the metabolite of benzo(a)pyrene in the presence of H2O2. - Highlights: • Construction of a novel DNA/hemin/nafion-graphene/GCE biosensor. • DNA damage induced by the benzo(a)pyrene metabolite was detected. • DPV analysis of benzo(a)pyrene provided a quantitative estimate of DNA damage. • Hemin/H2O2 system could mimic the cytochrome P450 to metabolize benzo(a)pyrene. - Abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed for the analysis of the benzo(a)pyrene PAH, which can produce DNA damage induced by a benzo(a)pyrene (BaP) enzyme-catalytic product. This biosensor was assembled layer-by-layer, and was characterized with the use of cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and atomic force microscopy. Ultimately, it was demonstrated that the hemin/nafion–graphene/GCE was a viable platform for the immobilization of DNA. This DNA biosensor was treated separately in benzo(a)pyrene, hydrogen peroxide (H2O2) and in their mixture, respectively, and differential pulse voltammetry (DPV) analysis showed that an oxidation peak was apparent after the electrode was immersed in H2O2. Such experiments indicated that in the presence of H2O2, hemin could mimic cytochrome P450 to metabolize benzo(a)pyrene, and a voltammogram of its metabolite was recorded. The DNA damage induced by this metabolite was also detected by electrochemical impedance and ultraviolet spectroscopy. Finally, a novel, indirect DPV analytical method for BaP in aqueous solution was developed based on the linear metabolite versus BaP concentration plot; this method provided a new, indirect, quantitative estimate of DNA damage

  15. 5α-Estrane-3β,17β-diol and 5β-estrane-3α,17β-diol: definitive screening biomarkers to sign nandrolone abuse in cattle?

    Science.gov (United States)

    Dervilly-Pinel, Gaud; Rambaud, Lauriane; Sitthisack, Parina; Monteau, Fabrice; Hewitt, S Armstrong; Kennedy, D Glenn; Le Bizec, Bruno

    2011-09-01

    17β-Nandrolone (17β-NT) is one of the most frequently misused anabolic steroids in meat producing animals. As a result of its extensive metabolism combined with the possibility of interferences with other endogenous compounds, detection of its illegal use often turns out to be a difficult issue. In recent years, proving the illegal administration of 17β-NT became even more challenging since the presence of endogenous presence of 17β-NT or some of its metabolite in different species was demonstrated. In bovines, 17α-NT can occur naturally in the urine of pregnant cows and recent findings reported that both forms can be detected in injured animals. Because efficient control must both take into account metabolic patterns and associated kinetics of elimination, the purpose of the present study was to investigate further some estranediols (5α-estrane-3β,17β-diol (abb), 5β-estrane-3α,17β-diol (bab), 5α-estrane-3β,17α-diol (aba), 5α-estrane-3α,17β-diol (aab) and 5β-estrane-3α,17α-diol (baa)) as particular metabolites of 17β-NT on a large number of injured (n=65) or pregnant (n=40) bovines. Whereas the metabolites abb, bab, aba and baa have previously been detected in urine up to several days after 17β-NT administration, the present study showed that some of the isomers abb (5α-estrane-3β,17β-diol) and bab (5β-estrane-3α,17β-diol) could not be detected in injured or pregnant animals, even at very low levels. This result may open a new way for the screening of anabolic steroid administration considering these 2 estranediols as biomarkers to indicate nandrolone abuse in cattle. PMID:21621615

  16. Non Heme System Asymmetric Epoxidation Reaction Made Progress

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Funded by the National Natural Science Foundation of China and the Chinese Academy of Sciences "Hundred Talents Program", the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences Oxo Synthesis and Selective Oxidation State Key Laboratory of biological and Biomimetic Catalytic task group has recently developed a new type of non heme enzyme simulation system, the system uses the benz- imidazole instead of four nitrogen ligands pyridine units, natural proline derivatives two amine instead of HMDA skeleton, the manganese complexes in asymmetric epoxidation reaction shown high activity, but in 1/10000 the amount of catalyst under conditions of high selectivity to obtain corresponding product, TON (Turnover numbers) up to 9600, TOF (Turnover frequency) up to 59000 h-1. It is currently reported the highest activity in epoxidation catalyst. Use the H202/AcOH or peracetic acid as oxidant, 180 isotope la- beling experiments, were found different degrees of 180 isotope labeling of epoxy products, won the first direct evidence of response is obtained by the high Mn O intermediates in the process, the work was pub- lished recently in Chem. Eur. J. (Chem. Eur. J. 2012, 18, 6750--6753. ).

  17. Fatigue test of epoxide resin at low temperature

    International Nuclear Information System (INIS)

    This chapter attempts to obtain experimental data at liquid helium temperature (LHeT), to examine the temperature dependence of fatigue properties and to provide reference data for magnet design. Describes the flexural test and the fatigue test. Uses a cured Bisphenol-A resin, the basis of many commercially available epoxide resins, which is subjected to a repeating load and is investigated for fatigue properties at cryogenic temperatures. Finds a deformation rate dependence in the epoxide resin in the flexural test and that the breaking load at the first loading in the fatigue test is lower than the static breaking load at RT (room temperature), LNT (liquid nitrogen temperature) and LHeT. Concludes that temperature decrease reduces the specimen sensitivity to fatigue loading, even though the absolute breaking load level on the load-endurance diagram at LNT is always larger than at LHeT. Finds that the load-endurance diagram obtained at LNT is similar to that at LHeT if the load axis is normalized in terms of the static breaking load. Points out that the crack initiation process is the rate-determining process in fatigue at cryogenic temperatures

  18. Separation of water-soluble metabolites of benzo[a]pyrene formed by cultured human colon

    DEFF Research Database (Denmark)

    1979-01-01

    A method has been developed to separate conjugated metabolites of benzo[a]pyrene into three major fractions: sulfate esters, glucuronides and glutathione conjugates. In cultured human colon, formation of sulfate esters and glutathione conjugates is the major conjugation pathway, while formation of...... glucuronides accounts for only 6 per cent of the water-soluble metabolites. Hydrolysis of the sulfate esters with arylsulfatase and the glucuronides with β-glucuronidase released metabolites of benzo[a]pyrene that were extractable with organic solvent. Separation of these metabolites by high-pressure liquid...... chromatography indicated that trans-4,5-dihydro-4,5-dihydroxybenzo[a]pyrene,7,8,9, 10-tetrahydro-7,8,9, 10-tetrahydroxybenzo[a]pyrene and trans-9, 10-dihydro-9, 10-dihydroxybenzo[a]pyrene were the major substrates for UDP-glucuronic acid transferase, while trans-7,8-dihydro-7,8-dihydroxybenzo[a]pyrene and 9...

  19. Benzo(a)pyrene activation and detoxification by human pulmonary alveolar macrophages and lymphocytes

    International Nuclear Information System (INIS)

    Comparisons of pulmonary alveolar macrophages and circulating lymphocytes from five smokers and five nonsmokers for their ability to metabolize benzo(a)pyrene as determined by high pressure liquid chromatography were carried out. Utilizing this approach, further investigation of activation and detoxification by several human cell types could provide the basis for more precise and comprehensive studies of carcinogen and drug metabolism in the human lung, and for a better assessment of cancer risk in selected populations

  20. Bacillus subtilis is a Potential Degrader of Pyrene and Benzo[a]pyrene

    Directory of Open Access Journals (Sweden)

    Lynette Ekunwe

    2005-08-01

    Full Text Available Polycyclic Aromatic Hydrocarbons (PAHs are a group of compounds that pose many health threats to human and animal life. They occur in nature as a result of incomplete combustion of organic matter, as well as from many anthropogenic sources including cigarette smoke and automobile exhaust. PAHs have been reported to cause liver damage, red blood cell damage and a variety of cancers. Because of this, methods to reduce the amount of PAHs in the environment are continuously being sought. The purpose of this study was to find soil bacteria capable of degrading high molecular weight PAHs, such as pyrene (Pyr and benzo[a]pyrene (BaP, which contain more than three benzene rings and so persist in the environment. Bacillus subtilis, identified by fatty acid methyl ester (FAME analysis, was isolated from PAH contaminated soil. Because it grew in the presence of 33μg/ml each of pyrene, 1-AP and 1-HP, its biodegradation capabilities were assessed. It was found that after a four-day incubation period at 30oC in 20μg/ml pyrene or benzo[a]pyrene, B. subtilis was able to transform approximately 40% and 50% pyrene and benzo[a]pyrene, respectively. This is the first report implicating B. subtilis in PAH degradation. Whether or not the intermediates resulting from the transformation are more toxic than their parent compounds, and whether B. subtilis is capable of mineralizing pyrene or benzo[a]pyrene to carbon dioxide and water, remains to be evaluated.

  1. Benzo(a)pyrene inhibits the role of the bioturbator Tubifex tubifex in river sediment biogeochemistry.

    Science.gov (United States)

    Mermillod-Blondin, F; Foulquier, A; Gilbert, F; Navel, S; Montuelle, B; Bellvert, F; Comte, G; Grossi, V; Fourel, F; Lecuyer, C; Simon, L

    2013-04-15

    The interactions between invertebrates and micro-organisms living in streambed sediments often play key roles in the regulation of nutrient and organic matter fluxes in aquatic ecosystems. However, benthic sediments also constitute a privileged compartment for the accumulation of persistent organic pollutants such as PAHs or PCBs that may affect the diversity, abundance and activity of benthic organisms. The objective of this study was to quantify the impact of sediment contamination with the PAH benzo(a)pyrene on the interaction between micro-organisms and the tubificid worm, Tubifex tubifex, which has been recognized as a major bioturbator in freshwater sediments. Sedimentary microcosms (slow filtration columns) contaminated or not with benzo(a)pyrene (3 tested concentrations: 0, 1 and 5 mg kg(-1)) at the sediment surface were incubated under laboratory conditions in the presence (100 individuals) or absence of T. tubifex. Although the surface sediment contaminations with 1 mg kg(-1) and 5 mg kg(-1) of benzo(a)pyrene did not affect tubificid worm survival, these contaminations significantly influenced the role played by T. tubifex in biogeochemical processes. Indeed, tubificid worms stimulated aerobic respiration, denitrification, dehydrogenase and hydrolytic activities of micro-organisms in uncontaminated sediments whereas such effects were inhibited in sediments polluted with benzo(a)pyrene. This inhibition was due to contaminant-induced changes in bioturbation (and especially bio-irrigation) activities of worms and their resulting effects on microbial processes. This study reveals the importance of sublethal concentrations of a contaminant on ecological processes in river sediments through affecting bioturbator-microbe interactions. Since they affect microbial processes involved in water purification processes, such impacts of sublethal concentrations of pollutants should be more often considered in ecosystem health assessment. PMID:23500821

  2. Chemistry of fullerene epoxides: synthesis, structure, and nucleophilic substitution-addition reactivity.

    Science.gov (United States)

    Tajima, Yusuke; Takeshi, Kazumasa; Shigemitsu, Yasuo; Numata, Youhei

    2012-01-01

    Fullerene epoxides, C₆₀O(n), having epoxide groups directly attached to the fullerene cage, constitute an interesting class of fullerene derivatives. In particular, the chemical transformations of fullerene epoxides are expected to play an important role in the development of functionalized fullerenes. This is because such transformations can readily afford a variety of mono- or polyfunctionalized fullerene derivatives while conserving the epoxy ring arrangement on the fullerene surface, as seen in representative regioisomeric fullerene polyepoxides. The first part of this review addresses the synthesis and structural characterization of fullerene epoxides. The formation of fullerene epoxides through different oxidation reactions is then explored. Adequate characterization of the isolated fullerene epoxides was achieved by concerted use of NMR and LC-MS techniques. The second part of this review addresses the substitution of fullerene epoxides in the presence of a Lewis acid catalyst. Most major substitution products have been isolated as pure compounds and their structures established through spectroscopic methods. The correlation between the structure of the substitution product and the oxygenation pattern of the starting materials allows elucidation of the mechanistic features of this transformation. This approach promises to lead to rigorous regioselective production of various fullerene derivatives for a wide range of applications. PMID:22634847

  3. Aminoacylase 1-catalysed deacetylation of bioactives epoxides mycotoxin-derived mercapturates; 3,4-epoxyprecocenes as models of cytotoxic epoxides.

    Science.gov (United States)

    Stocker, Pierre; Brunel, Jean Michel; de Rezende, Leandro; do Amaral, Antonia Tavares; Morelli, Xavier; Roche, Phillipe; Vidal, Nicolas; Giardina, Thierry; Perrier, Josette

    2012-08-01

    The mycotoxin aflatoxin B1 (AFB1) is a carcinogenic food contaminant which is metabolically activated by epoxydation. The metabolism of mycotoxins via the mercapturate metabolic pathway was shown, in general, to lead to their detoxication. Mercapturic acids thus formed (S-substitued-N-acetyl-l-cysteines) may be accumulated in the kidney and either excreted in the urine or desacetylated by Acylase 1 (ACY1) to yield cysteine S-conjugates. To be toxic, the N-acetyl-l-cysteine-S-conjugates first have to undergo deacetylation by ACY 1. The specificity and rate of mercapturic acid deacetylation may determine the toxicity, however the exact deacetylation processes involved are not well known. The aim of this study was to investigate the role of ACY1 in the toxicity of some bioactive epoxides from Aflatoxin B1. We characterized the kinetic parameters of porcine kidney and human recombinant aminoacylase-1 towards some aromatic and aliphatic-derived mercapturates analogue of mycotoxin-mercapturic acids and 3,4-epoxyprecocene, a bioactive epoxide derivated from aflatoxin. The deacetylation of mercapturated substrates was followed both by reverse phase HPLC and by TNBS method. Catalytic activity was discussed in a structure-function relationship. Ours results indicate for the first time that aminoacylase-1 could play an important role in deacetylating mercapturate metabolites of aflatoxin analogues and this process may be in relation with their cyto- and nephrotoxicity in human. PMID:22349737

  4. Biosynthesis of unnatural bacteriochlorophyll c derivatives esterified with α,ω-diols in the green sulfur photosynthetic bacterium Chlorobaculum tepidum.

    Science.gov (United States)

    Nishimori, Risato; Mizoguchi, Tadashi; Tamiaki, Hitoshi; Kashimura, Shigenori; Saga, Yoshitaka

    2011-09-13

    Unnatural bacteriochlorophyll (BChl) c derivatives possessing a hydroxy group at the terminus of a hydrocarbon chain at the 17-propionate were biosynthesized in the green sulfur photosynthetic bacterium Chlorobaculum tepidum. Addition of exogenous 1,8-octanediol, 1,12-dodecanediol, and 1,16-hexadecanediol in acetone to liquid cultures resulted in accumulation of BChl c monoesterified with the corresponding diols. The relative ratios of the novel BChl c derivatives esterified with 1,8-, 1,12-, and 1,16-diols to totally producing BChl c were 8.2, 50.2, and 57.6% in the cells grown with additive α,ω-diols at concentrations of 1.5, 0.06, and 0.06 mM, respectively, at the final concentration. The homologue composition of BChl c derivatives esterified with these α,ω-diols was similar to that of original, coexisting BChl c esterified with farnesol (BChl c(F)), suggesting that esterification of α,ω-diols occurred at the last step of the BChl c biosynthetic pathway by BChl c synthase, BchK, in the same manner as in BChl c(F). Chlorosomes, which were isolated from cells grown in the presence of exogenous α,ω-diols, contained a ratio and a composition of BChl c derivatives esterified with the diols similar to those in the whole cells, indicating that these BChl c derivatives were actually present in chlorosomes. Q(y) absorption bands of C. tepidum cells containing the novel BChl c derivatives were shifted to a shorter wavelength, although their bandwidths were analogous to those of cells obtained by normal cultivation. Circular dichroism spectra of cells that had BChl c derivatives esterified with α,ω-diols exhibited S-shaped signals in the Q(y) region, whose polarities were the reverse of those of cells grown in the normal medium and by supplementation with neat acetone as a control experiment. These spectral features of C. tepidum possessing BChl c derivatives esterified with α,ω-diols imply that the novel BChl c derivatives possessing a hydroxy group at the

  5. Cloisite 15Aº nanoclay as an effective PTC for the epoxidation of hydroxyl terminated polybutadiene (HTPB

    Directory of Open Access Journals (Sweden)

    Mir Mohammad Alavi Nikje

    2014-10-01

    Full Text Available A simple method is reported for the epoxidation of hydroxyl-terminated polybutadiene (HTPB by using in-situ generated dimethyl dioxirane (DMD as an oxidant and Cloisite 15Aº nanoclay as a phase-transfer catalyst (PTC. In order to find the optimum reaction conditions, real time analyses of the products as well as epoxidation progress, followed by ¹HNMR and FTIR techniques at various reaction times and different PTC concentrations, were done. Obtained data revealed the selectivity of DMD/ Cloisite 15Aº in predominant cis double bonds epoxidation in comparison with trans and pendant vinyl functional groups.

  6. Emerging sustainable technology for epoxidation directed toward plant oil-based plasticizers

    DEFF Research Database (Denmark)

    Chua, Seong-Chea; Xu, Xuebing; Guo, Zheng

    2012-01-01

    The chemical industry is increasingly looking toward sustainable technology to reduce the environmental impact and minimize the footprint of a chemical process. This work, which presents emerging technologies in academia and industry, discusses the development of advanced processes for the...... production of epoxidized plant oil-based plasticizers. The effects of the substrate structure, oxygen-donor properties, catalysts and biocatalysts on the specificity of the epoxidation reaction are intensively discussed. The progress in enzymatic epoxidation and the application of neoteric media, such as...

  7. Effect of phenobarbital on the level of translatable rat liver epoxide hydrolase mRNA.

    OpenAIRE

    Pickett, C B; Lu, A Y

    1981-01-01

    Liver poly(A)+RNA isolated from untreated and phenobarbital-treated rats has been translated in the rabbit reticulocyte cell-fre system in order to determine the level of translationally active epoxide hydrolase (EC 3.3.2.3) mRNA. The in vitro translation systems were immunoprecipitated with rabbit IgG prepared against purified epoxide hydrolase, and the amount of epoxide hydrolase synthesized by the lysate programmed with control and phenobarbital poly(A)+RNA was quantitated. The level of tr...

  8. Primary structure and catalytic mechanism of the epoxide hydrolase from Agrobacterium radiobacter AD1

    OpenAIRE

    Rink, R; Fennema, M.; Smids, M; Dehmel, U; Janssen, DB

    1997-01-01

    The epoxide hydrolase gene from Agrobacterium radiobacter AD1, a bacterium that is able to grow on epichlorohydrin as the sole carbon source, was cloned by means of the polymerase chain reaction with two degenerate primers based on the N-terminal and C-terminal sequences of the enzyme, The epoxide hydrolase gene coded for a protein of 294 amino acids with a molecular mass of 34 kDa, An identical epoxide hydrolase gene was cloned from chromosomal DNA of the closely related strain A, radiobacte...

  9. Detoxication strategy of epoxide hydrolase-the basis for a novel threshold for definable genotoxic carcinogens

    OpenAIRE

    Oesch, Franz; Hengstler, Jan Georg; Arand, Michael

    2004-01-01

    From our recent work on the three-dimensional structure of epoxide hydrolases we theoretically deduced the likelihood of a two-step catalytic mechanism that we and others have subsequently experimentally confirmed. Analysis of the rate of the two steps by us and by others show that the first step—responsible for removal of the reactive epoxide from the system—works extraordinarily fast (typically three orders of magnitude faster than the second step), sucking up the epoxide like a sponge. Reg...

  10. Analyses of effects of α-cembratrien-diol on cell morphology and transcriptome of Valsa mali var. mali.

    Science.gov (United States)

    Yan, Ning; Du, Yongmei; Liu, Xinmin; Zhang, Hongbo; Liu, Yanhua; Shi, John; Xue, Sophia Jun; Zhang, Zhongfeng

    2017-01-01

    The objective of this work was to study the underlying mechanisms of growth inhibition of Valsa mali var. mali, the causative pathogen of apple tree canker disease, by α-cembratrien-diol. The half maximal inhibitory concentration of α-cembratrien-diol against V. mali var. mali is 18.0mg/L. Treatment of V. mali var. mali with α-cembratrien-diol resulted in various mycelial and cellular abnormalities, and the up- and down-regulation of 94 and 170 differentially expressed genes, respectively. Gene Ontology term enrichment analysis revealed that α-cembratrien-diol substantially altered the expression of genes involved in the redox process, tetrapyrrole binding, coenzyme binding, heme binding, and iron binding. Kyoto Encyclopedia of Genes and Genomes enrichment analysis also showed significant enrichment of specific metabolic pathways involving the set of differentially expressed genes. The present study will assist in the development of alternative α-cembratrien-diol-based biological control agents and ultimately facilitate organic apple production. PMID:27507455

  11. Immunogenicity of a promiscuous T cell epitope peptide based conjugate vaccine against benzo[a]pyrene: redirecting antibodies to the hapten.

    Directory of Open Access Journals (Sweden)

    Mario T Schellenberger

    Full Text Available The prototype polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P is an environmental pollutant and food contaminant of epidemiological importance. To protect against adverse effects of this ubiquitous carcinogen, we developed an immunoprophylactic strategy based on a B[a]P-protein conjugate vaccine to induce B[a]P specific antibodies (Grova et al., Vaccine. 2009;27:4142-51. Here, we investigated in mice the efficacy of B[a]P-peptide conjugates based on promiscuous T cell epitopes (TCE into further improve this approach. We showed that B[a]P-peptide conjugates induced very different levels of hapten-specific antibodies with variable functional efficacy, depending on the carrier. In some cases peptide carriers induced a more efficient antibody response against B[a]P than tetanus toxoid as a protein carrier, with the capacity to sequester more B[a]P in the blood. Reducing the carrier size to a single TCE can dramatically shift the antibody bias from the carrier to the B[a]P. Conjugates based on the TCE FIGITEL induced the best anti-hapten response and no antibodies against the carrier peptide. Some peptide conjugates increased the selectivity of the antibodies for the activated metabolite 7,8-diol-B[a]P and B[a]P by one or two orders of magnitude. The antibody efficacy was also demonstrated in their ability to sequester B[a]P in the blood and modulate its faecal excretion (15-56%. We further showed that pre-existing immunity to the carrier from which the TCE was derived did not reduce the immunogenicity of the peptide conjugate. In conclusion, we showed that a vaccination against B[a]P using promiscuous TCEs of tetanus toxin as carriers is feasible even in case of a pre-existing immunity to the toxoid and that some TCE epitopes dramatically redirect the antibody response to the hapten. Further studies to demonstrate a long-term protection of an immunoprophylactic immunisation against B[a]P are warranted.

  12. Immunogenicity of a promiscuous T cell epitope peptide based conjugate vaccine against benzo[a]pyrene: redirecting antibodies to the hapten.

    Science.gov (United States)

    Schellenberger, Mario T; Grova, Nathalie; Farinelle, Sophie; Willième, Stéphanie; Revets, Dominique; Muller, Claude P

    2012-01-01

    The prototype polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P) is an environmental pollutant and food contaminant of epidemiological importance. To protect against adverse effects of this ubiquitous carcinogen, we developed an immunoprophylactic strategy based on a B[a]P-protein conjugate vaccine to induce B[a]P specific antibodies (Grova et al., Vaccine. 2009;27:4142-51). Here, we investigated in mice the efficacy of B[a]P-peptide conjugates based on promiscuous T cell epitopes (TCE) into further improve this approach. We showed that B[a]P-peptide conjugates induced very different levels of hapten-specific antibodies with variable functional efficacy, depending on the carrier. In some cases peptide carriers induced a more efficient antibody response against B[a]P than tetanus toxoid as a protein carrier, with the capacity to sequester more B[a]P in the blood. Reducing the carrier size to a single TCE can dramatically shift the antibody bias from the carrier to the B[a]P. Conjugates based on the TCE FIGITEL induced the best anti-hapten response and no antibodies against the carrier peptide. Some peptide conjugates increased the selectivity of the antibodies for the activated metabolite 7,8-diol-B[a]P and B[a]P by one or two orders of magnitude. The antibody efficacy was also demonstrated in their ability to sequester B[a]P in the blood and modulate its faecal excretion (15-56%). We further showed that pre-existing immunity to the carrier from which the TCE was derived did not reduce the immunogenicity of the peptide conjugate. In conclusion, we showed that a vaccination against B[a]P using promiscuous TCEs of tetanus toxin as carriers is feasible even in case of a pre-existing immunity to the toxoid and that some TCE epitopes dramatically redirect the antibody response to the hapten. Further studies to demonstrate a long-term protection of an immunoprophylactic immunisation against B[a]P are warranted. PMID:22666501

  13. On the mechanism of radical fragmentation of α-dioles and some of their derivatives

    International Nuclear Information System (INIS)

    Studied is the composition of radiolysis products of deluted deaerated aqueous solutions of 1.2-dimethoxyethane and some of 1.3-dioxolanes. The solutions were leached (pH 12-13) to prevent hydrolysis of both initial and final products. Cs137 was used as a source of γ-radiation. Absorbed dose rate is equal to 4x1015 eV/mlxs. On the basis of the results obtained and literary data on radical fragmentation of α-dioles a possibility of ROCHCH2OR' particle decomposition according to the coordinated mechanism is discussed

  14. Colloidal and Chemical Properties of Polyesters Based on Glutamic acid and Diols of Different Nature

    Directory of Open Access Journals (Sweden)

    Puzko N.V.

    2012-08-01

    Full Text Available The paper describes synthesis method and colloid-chemical properties of novel α-amino acid based polyesters with controllable hydrophilic-lipophillic balance. Glutamic acid and diols of different nature based polyesters were obtained via low-temperature activated polyesterefication. Such polymers are able to form micellar structures in self-stabilized water dispersion. Solubilization of water insoluble dyes Sudan and toluene in polymer water solution was studied. Due to micelle forming ability and prognosticated biodegradability to non-toxic products, obtained polymers are promising materials for formation of novel dispersed drug delivery systems.

  15. Kinetics of complexation and oxidation of ethanolamine and diols by silver(II)

    International Nuclear Information System (INIS)

    The oxidation of ethanolamine (EtA), ethylene glycol, and several other diols by Ag(II) has been studied at pH approx. 8.5. In the basic pH range, complexation of the substrate by Ag(II) has been found to take place in two steps by successive ligand uptake. Complexation rates are higher by 1 order of magnitude in the basic pH range as compared to the acidic pH range. Oxidation then takes place through intramolecular electron transfer from substrate to Ag(II) within the complex. Oxidation rates for cis- and trans-1,2-cyclohexanediols are quite similar

  16. A Facile and Efficient Synthesis of (15R)-Latanoprost from Chiral Precursor Corey Lactone Diol

    Indian Academy of Sciences (India)

    K Vijendhar; B Srinivas; Sathyanarayana Boodida

    2015-11-01

    An efficient asymmetric synthetic route for the synthesis of anti-glaucoma agent, (15R)-latanoprost using Corey lactone diol as chiral substrate under Swern oxidation, allylic reduction and Wittig reaction conditions has been developed. In this method, reduction of keto and alkene functional groups has been achieved in a single step using low cost catalyst NiCl2/NaBH4 in methanol. This new synthetic protocol is a good alternative for the synthesis of latanoprost with high stereo selectivity and improved yield.

  17. Synthesis and characterization of segmented polyurethanes based on amphiphilic polyether diols.

    Science.gov (United States)

    Lan, P N; Corneillie, S; Schacht, E; Davies, M; Shard, A

    1996-12-01

    Segmented polyurethanes (SPUs) based on polyethylene glycol (PEG), polypropylene glycol (PPG) and a series of Pluronics with different ethylene oxide/propylene oxide ratios (EO/PO) and molecular weights were prepared. Different diisocyanates were used for making SPUs: 4,4-diphenylmethane diisocyanate (MDI), 4,4-dicyclohexylmethane diisocyanate (MDCI), hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI). 1,4-Butane diol (BD) and ethylene diamine (ED) were used as chain extenders. The polymers obtained were characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). The microphase morphology (phase separation and phase mixing) is discussed in more detail. PMID:8968523

  18. 2-[(5-Chloro-2-oxidobenzylideneazaniumyl]-2-methylpropane-1,3-diol

    Directory of Open Access Journals (Sweden)

    Dong-Yue Wang

    2012-02-01

    Full Text Available The title compound, C11H14ClNO3, was prepared by the condensation of equimolar quantities of 5-chlorosalicylaldehyde and 2-amino-2-methylpropane-1,3-diol in methanol. In the crystal, it exists in the zwitterionic form, with nominal proton transfer from the phenol group to the imine N atom. This results in the formation of an intramolecular N—H...O hydrogen bond, which generates an S(6 ring. Intermolecular O—H...O hydrogen bonds arise from the hydroxy groups, forming (001 sheets.

  19. Structure of a bacterial homologue of vitamin K epoxide reductase

    Energy Technology Data Exchange (ETDEWEB)

    Li, Weikai; Schulman, Sol; Dutton, Rachel J.; Boyd, Dana; Beckwith, Jon; Rapoport, Tom A. (Harvard-Med); (HHMI)

    2010-03-19

    Vitamin K epoxide reductase (VKOR) generates vitamin K hydroquinone to sustain {gamma}-carboxylation of many blood coagulation factors. Here, we report the 3.6 {angstrom} crystal structure of a bacterial homologue of VKOR from Synechococcus sp. The structure shows VKOR in complex with its naturally fused redox partner, a thioredoxin-like domain, and corresponds to an arrested state of electron transfer. The catalytic core of VKOR is a four transmembrane helix bundle that surrounds a quinone, connected through an additional transmembrane segment with the periplasmic thioredoxin-like domain. We propose a pathway for how VKOR uses electrons from cysteines of newly synthesized proteins to reduce a quinone, a mechanism confirmed by in vitro reconstitution of vitamin K-dependent disulphide bridge formation. Our results have implications for the mechanism of the mammalian VKOR and explain how mutations can cause resistance to the VKOR inhibitor warfarin, the most commonly used oral anticoagulant.

  20. Photo stabilizing Efficiency of PVC Based On Epoxidized Oleic Acid

    International Nuclear Information System (INIS)

    The photo stabilization of poly (vinyl chloride) (PVC) films by epoxidized oleic acid compounds was investigated. The PVC films containing concentration of complexes 0.5 % by weight were produced by the casting method from tetrahydrofuran (THF) solvent. The photo stabilization activities of these compounds were determined by monitoring the carbonyl, polyene and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked (using THF as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PVC films was evaluated and found to range between 4.98x10-8 and 8.72x10-8. According to the experimental results obtained, mechanisms were suggested depending on the structure of the additive (oleic acid). (author)

  1. Microwave absorption properties of barium titanate/epoxide resin composites

    International Nuclear Information System (INIS)

    Nano-barium titanate (BT) was prepared by a sol-gel method. The prepared powders were characterized by x-ray powder diffraction and transmission electron microscopy. The complex relative dielectric permittivity (ε = ε' - jε-prime) and magnetic permeability (μ = μ' - jμ-prime) of the BT powders were measured in the frequency range 8 ∼ 18 GHz. The BT/epoxide resin (EP) composite with different volume contents was investigated. The effects of thickness on the BT/EP composite were studied. It was found that an optimum thickness and contents of the absorber can yield the maximum reflection loss which could be obtained over a broad frequency region in the X and Ku bands. Our results indicate that BT could be a promising microwave absorption material

  2. Lap test of epoxide resin at cryogenic temperatures

    International Nuclear Information System (INIS)

    This chapter attempts to gather basic information about the initiation of defects, which may control magnet degradation, and to clarify the problems concerning the stability of superconducting magnets. Divides the study into 3 parts: the race track coil test, in which coils are stretched at low temperatures in order to observe the boundary behavior under stressed conditions; a compression test of epoxide resins to determine the mechanical properties of the basic material; and a lap test to obtain basic information about the mechanical behavior of the potting materials as the adhesive which fixes the wires to each other. Concludes that the boundary behavior between wire and potting material may control the performance of magnets in practice; materials used in composite form such as impregnating materials should be selected after careful consideration not only of the mechanical properties themselves but also of adhesive strength; and the cohesive force does not always reflect the adhesive strength

  3. Low temperature properties of carbon fibre reinforced epoxide resins

    International Nuclear Information System (INIS)

    The material properties of carbon fibre reinforced epoxide resins are studied for applications at room temperature, as well as the high ratio of strength and stiffness to specific weight in structures. The test equipment, the specimens and the manufacturing procedures are described. Test equipment for low temperatures are illustrated in photos and charts. Results of mechanical and thermal tests are given and an investigation on lugs for a cryogenic tank for space application is proposed. Conclusions include the fact that most mechanical properties of unidirectional carbon fibre reinforced composites show higher values at low temperatures. Results of fatigue tests with glass-, carbon- and aramid compositions (Lugs) show a remarkable increase in fatigue life at low temperatures relative to room temperature

  4. Conformational diversity and enantioconvergence in potato epoxide hydrolase 1.

    Science.gov (United States)

    Bauer, P; Carlsson, Å Janfalk; Amrein, B A; Dobritzsch, D; Widersten, M; Kamerlin, S C L

    2016-06-28

    Potato epoxide hydrolase 1 (StEH1) is a biocatalytically important enzyme that exhibits rich enantio- and regioselectivity in the hydrolysis of chiral epoxide substrates. In particular, StEH1 has been demonstrated to enantioconvergently hydrolyze racemic mixes of styrene oxide (SO) to yield (R)-1-phenylethanediol. This work combines computational, crystallographic and biochemical analyses to understand both the origins of the enantioconvergent behavior of the wild-type enzyme, as well as shifts in activities and substrate binding preferences in an engineered StEH1 variant, R-C1B1, which contains four active site substitutions (W106L, L109Y, V141K and I155V). Our calculations are able to reproduce both the enantio- and regioselectivities of StEH1, and demonstrate a clear link between different substrate binding modes and the corresponding selectivity, with the preferred binding modes being shifted between the wild-type enzyme and the R-C1B1 variant. Additionally, we demonstrate that the observed changes in selectivity and the corresponding enantioconvergent behavior are due to a combination of steric and electrostatic effects that modulate both the accessibility of the different carbon atoms to the nucleophilic side chain of D105, as well as the interactions between the substrate and protein amino acid side chains and active site water molecules. Being able to computationally predict such subtle effects for different substrate enantiomers, as well as to understand their origin and how they are affected by mutations, is an important advance towards the computational design of improved biocatalysts for enantioselective synthesis. PMID:27049844

  5. Unexpected Stereospecific Rearrangement-Addition Reaction of Trisubstituted Gibberellin Epoxides with Trimethylaluminium

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel rearrangement-addition reaction of trisubstituted gibberellin epoxides with trimethylaluminium is reported. The reaction proceeds stereospecifically to give tertiary methyl alcohols. The possible mechanism for the reaction is also discussed.

  6. Physico-mechanical properties of asphalt concrete based on road bitumen modified by rapeseed oil epoxide

    OpenAIRE

    Nykypanchuk, Mykhailo; Hrynchuk, Yurii; Olchovyk, Mykola

    2013-01-01

    The investigation results of type B fine asphalt concrete and its form modified by rapeseed oil epoxide are represented. The efficiency of ERO addition and its positive effect on the physico-mechanical properties of asphalt concrete has been established.

  7. Mono-lacunary PrIII-Polyoxotungstate: Epoxidation of Alkenes with Unusual Selectivity

    Institute of Scientific and Technical Information of China (English)

    YANG Feng; MA Li; MA Zhi-Yuan

    2011-01-01

    The utilization of polyoxometalates (POMs) or their derivatives as homogeneous or heterogeneous catalysts in alkene epoxidation is a subject of considerable research activity[1]. The limitation to the use of POMs in these catalytic reactions is either their relatively low selectivity in epoxide formation or applicability for a rather limited type of alkenes. Therefore, it would be beneficial if the catalysts bear high selectivity for epoxidation and are applicable for a rather wide variety of alkenes, which is desirable in industrial processes and also vital for the selection of an ideal catalyst[2]. In search for an efficient and practical epoxidation method to utilize aqueous H2O2 as terminal oxidant, we focus on the rare-earth complexes with lacunary POM ligands.

  8. Purification and characterisation of a novel enantioselective epoxide hydrolase from Aspergillus niger M200

    Czech Academy of Sciences Publication Activity Database

    Kotík, Michael; Kyslík, Pavel

    2006-01-01

    Roč. 1760, - (2006), s. 245-252. ISSN 0006-3002 Institutional research plan: CEZ:AV0Z50200510 Keywords : epoxide hydrolase * enantioselectivity * aspergillus niger Subject RIV: EE - Microbiology, Virology

  9. A Computational Study of Acid Catalyzed Aerosol Reactions of Atmospherically Relevant Epoxides

    Science.gov (United States)

    Epoxides are important intermediates of atmospheric isoprene oxidation. Their subsequent reactions in the particle phase lead to the production of organic compounds detected in ambient aerosols. We apply density functional theory to determine the important kinetic factors that ...

  10. Development of cationically initiated UV curable coating systems based on cyclo-aliphatic diepoxide, ENR, epoxidized poly-butadiene and epoxidized soybean oil

    International Nuclear Information System (INIS)

    Epoxidized Natural Rubber (ENR) had been earlier found to impart toughness to otherwise brittle epoxy resin. Since the high viscosity of solutions of ENR in reactive solvent glycidyl methacrylate,imposed a limitation to the incorporation of higher percentages of the elastomer to the epoxy systems, experiments were initiated to employ the liquid elastomer, namely, epoxidized polybutadiene In the formulations. 'Mixture Design', a statistical experimental design, was adopted to study the effect of compositional and process variables on the curing of surface coatings formulated from the above system by UV radiation initiated by cationic photo-initiators. This paper also reports the results of the experiments carded out with epoxidized soybean oil Employed as a flexibilizer in the cycloaliphatic epoxy-ENR system

  11. Stereoselective synthesis of epoxides and diepoxides. Applications in total synthesis of natural products and analogues

    OpenAIRE

    García Ruiz, María Cristina

    2014-01-01

    The present work is on the total synthesis of the natural compounds and/or analogues of Bengamides, Gummiferol and Depudecin. The target molecules, selected in virtue of their prominent biological activity as antibiotic and antitumor agents are featured by the presence of one or two epoxide groups and were synthesized by application of a novel methodology of asymmetric epoxidation based on the use of a new class of chiral sulfur ylides. The aim of every total synthesis discussed in this thesi...

  12. Cure reaction and phase behavior of liquid crystalline epoxides-anhydride systems

    Institute of Scientific and Technical Information of China (English)

    Li Yan Liang; Shao Ping Ren; Yi Quan Zheng; Man Geng Lu

    2007-01-01

    A series of novel liquid crystalline epoxides with lateral substituents were cured with anhydrides and the cure kinetics was investigated by non-isothermal DSC technique. The results showed that the lengths of lateral substituents have great effect on the value of Ea. The curing reaction became less active, when the liquid crystalline epoxides have long lateral substituents and were controlled by diffusion at the late stage of cure. A nematic structure was observed by POM and XRD.

  13. Epoxide-Opening Cascades in the Synthesis of Polycyclic Polyether Natural Products

    OpenAIRE

    Vilotijevic, Ivan; Jamison, Timothy F.

    2009-01-01

    The structural features of polycyclic polyether natural products can, in some cases, be traced to their biosynthetic origin. However in case that are less well understood, only biosynthetic pathways that feature dramatic, yet speculative, epoxide-opening cascades are proposed. We summarize how such epoxide-opening cascade reactions have been used in the synthesis of polycyclic polyethers (see scheme) and related natural products. The group of polycyclic polyether natural products is of sp...

  14. The encapsulation of spent ion-exchange resins in an epoxide resin

    International Nuclear Information System (INIS)

    Inorganic and organic IX resins have been incorporated into a water-tolerant epoxide resin system. The effect of γ-irradiation to 5 x 109 rads on the mechanical properties of samples containing wet IX resins has been investigated. It was found that although there is a marked embrittlement of the epoxide matrix, useful mechanical properties are retained up to this dose. Gas evolution studies under irradiation and thermogravimetric analyses have also been carried out. (author)

  15. Selective epoxidation of allylic alcohols with a titania-silica aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Dusi, M.; Mallat, T.; Baiker, A. [Lab. of Technical Chemistry, Swiss Federal Inst. of Technology, ETH-Zentrum, Zuerich (Switzerland)

    1998-12-31

    An amorphous mesoporous titania-silica aerogel (20 wt%TiO{sub 2} - 80 wt% SiO{sub 2}) and tert.-butylhydroperoxide (TBHP) have been used for the epoxidation of various allylic alcohols. Allylic alcohols possessing an internal double bond were more reactive than those with a terminal C=C bond. Epoxide selectivities could be improved by addition of (basic) zeolite 4 A and NaHCO{sub 3} to the reaction mixture. (orig.)

  16. A Dynamic Supramolecular System Exhibiting Substrate Selectivity in the Catalytic Epoxidation of Olefins

    DEFF Research Database (Denmark)

    Jonsson, Stefan; Odille, Fabrice G. J.; Norrby, Per-Ola;

    2005-01-01

    A dynamic supramolecular system involving hydrogen bonding between a Mn(III) salen catalyst and a Zn(II) porphyrin receptor exhibits selectivity for pyridine appended cis-beta-substituted styrene derivatives over phenyl appended derivatives in a catalytic epoxidation reaction.......A dynamic supramolecular system involving hydrogen bonding between a Mn(III) salen catalyst and a Zn(II) porphyrin receptor exhibits selectivity for pyridine appended cis-beta-substituted styrene derivatives over phenyl appended derivatives in a catalytic epoxidation reaction....

  17. Cloisite 15Aº nanoclay as an effective PTC for the epoxidation of hydroxyl terminated polybutadiene (HTPB)

    OpenAIRE

    Mir Mohammad Alavi Nikje; Maryam Gholi Nataj

    2014-01-01

    A simple method is reported for the epoxidation of hydroxyl-terminated polybutadiene (HTPB) by using in-situ generated dimethyl dioxirane (DMD) as an oxidant and Cloisite 15Aº nanoclay as a phase-transfer catalyst (PTC). In order to find the optimum reaction conditions, real time analyses of the products as well as epoxidation progress, followed by ¹HNMR and FTIR techniques at various reaction times and different PTC concentrations, were done. Obtained data revealed the selectivity of DMD/ Cl...

  18. Biocatalysis of azidolysis of epoxides: Computational evidences on the role of halohydrin dehalogenase (HheC)

    Indian Academy of Sciences (India)

    Dhurairajan senthilnathan; Venkatachalam Tamilmani; Ponnambalam Venuvanalingam

    2011-05-01

    Biocatalytic azidolysis of 9 unsymmetrical epoxides by halohydrin dehalogenase enzyme (HheC) in gas phase and uncatalysed azidolysis of the same epoxides in gas phase and in aqueous solution have been modelled at DFT level. Aliphatic epoxides (1-6) and aromatic epoxides (9) undergo cleavage while styrene oxide (7) and -nitro styrene (8) oxide prefer cleavage in the gas phase. Inclusion of aqueous solvation effect via Polarizable Continuum Model (PCM) increases the activation barrier and makes the reaction endothermic due to extensive solvation of azide anion and oxido anionic products, but does not alter the regioselectivity. Halohydrin dehalogenase from Agrobacterium radiobactor AD1 catalyses (E1-E9) ring opening of all these epoxides by azide ion with selectivity and the reversal of selectivity in epoxide 7 and 8 is notable. These reactions follow, in both enzymatic and non-enzymatic environment, S2 mechanism. Calculations while agreeing totally with experimental results offer better insights on the factors determining the regioselectivity and particularly the role of enzyme. Active site model and crystal structure data reveal that the Tyr145 and Ser132 form weak hydrogen bonds with epoxide oxygen lone pair and form reactant enzyme complex (REC). The enzyme complex activates the epoxide ring towards azidolysis. The NBO deletion and second order perturbation analyses clearly bring out the role of catalytic duo Tyr145 and Ser132 and particularly shed light on the dominant contribution of Tyr145 in selectively activating C-O bond. The present results indicate that Arg149 or other residues in the pocket do not seem to have any significant effect on the reaction.

  19. Isocyanate Reduction by Epoxide Substitution of Alcohols for Polyurethane Bioelastomer Synthesis

    OpenAIRE

    Lubguban, Arnold A.; Lozada, Zuleica R.; Yuan-Chan Tu; Hongyu Fan; Fu-Hung Hsieh; Galen J. Suppes

    2011-01-01

    A phosphate ester-forming reaction was carried out by mixing epoxidized soybean oil with up to 1.5% o-phosphoric acid. In situ oligomerization took effect almost instantly producing a clear, homogeneous, highly viscous, and a low-acid product with a high average functionality. The resulting epoxide was used as a reactant for urethane bioelastomer synthesis and evaluated for rigid foam formulation. Results have shown that with a number of catalysts tested phosphoric acid significantly enhances...

  20. Effect of the third component on solidification heat of spent resin in solidification process with epoxide

    International Nuclear Information System (INIS)

    Effect of the third component on solidification heat of IER-epoxide system is described. In order to decrease solidification heat (or temperature), the Fontainnebleau sand is chosen as inert filling agent. According to measurement of solidified from properties (including hardness and inflation in water and solidification heat), optimum constituent is determined, that is: IER-50%; Epoxide-40%; Sand-10%. It can meet the temperature requirement in solidification process

  1. The Development of Endo-Selective Epoxide-Opening Cascades in Water†

    OpenAIRE

    Morten, Christopher J.; Byers, Jeffery A.; Van Dyke, Aaron R.; Vilotijevic, Ivan; Jamison, Timothy F.

    2009-01-01

    This tutorial review traces the development of endo-regioselective epoxide-opening reactions in water. Templated, water-promoted epoxide-opening cyclization reactions can offer rapid access to subunits of the ladder polyethers, a fascinating and complex family of natural products. This review may be of interest to those curious about the ladder polyethers and their hypothesized biogenesis, about organic reactions in water, and about the development and application of cascade reactions in orga...

  2. Total synthesis of (+/-)-11 alpha-hydroxyprogesterone by cyclization of a polyunsaturated epoxide.

    OpenAIRE

    van Tamelen, E E; Faler, D L

    1985-01-01

    The total synthesis of a typical 11-hydroxylated steroid, (+/-)-11 alpha-hydroxyprogesterone, was achieved by picric acid-catalyzed tricyclization of a polyunsaturated epoxide appropriately substituted with ketal, hydroxyl, and acetylenic units. This epoxide was prepared by a multistage sequence featuring two successive alkylations of intermediary, monocyclic sulfones. The first sulfone intermediate was obtained by means of a short sequence starting from levulinic acid and diethyl succinate a...

  3. Unexpected epoxide formation in the gas-phase photooxidation of isoprene

    DEFF Research Database (Denmark)

    Paulot, Fabien; Crounse, John D; Kjaergaard, Henrik G; Kürten, Andreas; St Clair, Jason M; Seinfeld, John H; Wennberg, Paul O

    2009-01-01

      Emissions of nonmethane hydrocarbon compounds to the atmosphere from the biosphere exceed those from anthropogenic activity. Isoprene, a five-carbon diene, contributes more than 40% of these emissions. Once emitted to the atmosphere, isoprene is rapidly oxidized by the hydroxyl radical OH. We r...... per year-of these epoxides to the atmosphere. The discovery of these highly soluble epoxides provides a missing link tying the gas-phase degradation of isoprene to the observed formation of organic aerosols....

  4. Synthesis and characterization of acrylated epoxidized soybean oil for UV cured coatings

    OpenAIRE

    Habib, Firdous; Bajpai, Madhu

    2011-01-01

    This paper investigates the curing of biodegradable polymer films which were synthesized from soybean oil through the ultraviolet radiation and their stability against thermal degradation. In this study the epoxidation of soybean oil has been carried out via peracetic method. Further, an epoxy acrylate resin was synthesized from the epoxidized soybean oil (ESO) by using acrylic acid monomer. Triethylamine (TEA) and hydroquinone were used as a catalyst and inhibitor respectively. The acrylatio...

  5. 6-Methyl-1,3,5-triazine-2,4-diamine butane-1,4-diol monosolvate

    Directory of Open Access Journals (Sweden)

    Rajni M. Bhardwaj

    2012-12-01

    Full Text Available The title co-crystal, C4H7N5·C4H10O2, crystallizes with one molecule of 6-methyl-1,3,5-triazine-2,4-diamine (DMT and one molecule of butane-1,4-diol in the asymmetric unit. The DMT molecules form ribbons involving centrosymmetric R22(8 dimer motifs between DMT molecules along the c-axis direction. These ribbons are further hydrogen bonded to each other through butane-1,4-diol, forming sheets parallel to (121.

  6. Iridium- and ruthenium-catalysed synthesis of 2,3-disubstituted indoles from anilines and vicinal diols

    DEFF Research Database (Denmark)

    Tursky, Matyas; Lorentz-Petersen, Linda Luise Reeh; Olsen, L. B.;

    2010-01-01

    does not require any stoichiometric additives and only produces water and dihydrogen as byproducts. Anilines containing methyl, methoxy, chloro and fluoro substituents can participate in the cyclocondensation. Meta-substituted anilines give good regioselectivity for 6-substituted indoles, while...... unsymmetrical diols afford excellent regioselectivity for the indole isomer with an aryl or large alkyl group in the 2-position. The mechanism for the cyclocondensation presumably involves initial formation of the alpha-hydroxyketone from the diol. The ketone subsequently reacts with aniline to generate the...

  7. Determination of the level of benzo[a]pyrene in fatty foods and food supplements

    OpenAIRE

    Van Der Wielen-Hustinx, Jacqueline Claire Agnes; Jansen, John; Martena, Martijn J.; De Groot, Henk; In T Veld, Paul

    2006-01-01

    Abstract A routine method was developed for the quantification of benzo[a]pyrene (BaP) in edible oils and food supplements. BaP is often taken as an indicator of the presence of polycyclic aromatic hydrocarbons. The method consists of on-line LC-clean up followed by injection to an HPLC-system connected with fluorescence detection. The method has good performance characteristics and gave good results in proficiency tests. From 2002 to 2004 about 1350 samples, oils and food supp...

  8. The Cigarette Smoke Carcinogen Benzo[a]pyrene Enhances Human Papillomavirus Synthesis▿

    OpenAIRE

    Alam, Samina; Conway, Michael J; Chen, Horng-Shen; Meyers, Craig

    2007-01-01

    Epidemiological studies suggest that cigarette smoke carcinogens are cofactors which synergize with human papillomavirus (HPV) to increase the risk of cervical cancer progression. Benzo[a]pyrene (BaP), a major carcinogen in cigarette smoke, is detected in the cervical mucus and may interact with HPV. Exposure of cervical cells to high concentrations of BaP resulted in a 10-fold increase in HPV type 31 (HPV31) viral titers, whereas treatment with low concentrations of BaP resulted in an increa...

  9. Electrochemical detection of benzo(a)pyrene and related DNA damage using DNA/hemin/nafion–graphene biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Yongnian, E-mail: ynni@ncu.edu.cn [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Department of Chemistry, Nanchang University, Nanchang 330031 (China); Wang, Pingping; Song, Haiyan [Department of Chemistry, Nanchang University, Nanchang 330031 (China); Lin, Xiaoyun [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Department of Chemistry, Nanchang University, Nanchang 330031 (China); Kokot, Serge, E-mail: s.kokot@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane 4001 (Australia)

    2014-04-01

    Graphical abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed to quantitatively study the DNA damage induced by the metabolite of benzo(a)pyrene in the presence of H{sub 2}O{sub 2}. - Highlights: • Construction of a novel DNA/hemin/nafion-graphene/GCE biosensor. • DNA damage induced by the benzo(a)pyrene metabolite was detected. • DPV analysis of benzo(a)pyrene provided a quantitative estimate of DNA damage. • Hemin/H{sub 2}O{sub 2} system could mimic the cytochrome P450 to metabolize benzo(a)pyrene. - Abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed for the analysis of the benzo(a)pyrene PAH, which can produce DNA damage induced by a benzo(a)pyrene (BaP) enzyme-catalytic product. This biosensor was assembled layer-by-layer, and was characterized with the use of cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and atomic force microscopy. Ultimately, it was demonstrated that the hemin/nafion–graphene/GCE was a viable platform for the immobilization of DNA. This DNA biosensor was treated separately in benzo(a)pyrene, hydrogen peroxide (H{sub 2}O{sub 2}) and in their mixture, respectively, and differential pulse voltammetry (DPV) analysis showed that an oxidation peak was apparent after the electrode was immersed in H{sub 2}O{sub 2}. Such experiments indicated that in the presence of H{sub 2}O{sub 2}, hemin could mimic cytochrome P450 to metabolize benzo(a)pyrene, and a voltammogram of its metabolite was recorded. The DNA damage induced by this metabolite was also detected by electrochemical impedance and ultraviolet spectroscopy. Finally, a novel, indirect DPV analytical method for BaP in aqueous solution was developed based on the linear metabolite versus BaP concentration plot; this method provided a new, indirect, quantitative estimate of DNA damage.

  10. Ruthenium-catalysed synthesis of 2- and 3-substituted quinolines from anilines and 1,3-diols

    DEFF Research Database (Denmark)

    Monrad, Rune Nygaard; Madsen, Robert

    2011-01-01

    A straightforward synthesis of substituted quinolines is described by cyclocondensation of anilines with 1,3-diols. The reaction proceeds in mesitylene solution with catalytic amounts of RuCl3·xH 2O, PBu3 and MgBr2·OEt2. The transformation does not require any stoichiometric additives and only pr...

  11. The influence of hard segment content on dynamic mechanical properties of segmented polyurethanes based on polycarbonate diols

    Czech Academy of Sciences Publication Activity Database

    Bera, O.; Pavličević, J.; Špírková, Milena; Strachota, Adam; Poreba, Rafal; Jovičić, M.; Budinski-Simendic, J.

    Belgrade : Institute of Technical Sciences of the Serbian Academy of Sciences & Arts, 2010 - (Uskoković, D.). s. 125 [Annual Conference /12./ YUCOMAT 2010. 06.09.2010-10.09.2010, Herceg Novi] R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane * polycarbonate diol Subject RIV: CD - Macromolecular Chemistry

  12. Electrocatalytic oxidation of alcohols and diols in a biphasic medium using CeIV methanesulfonate as mediator

    International Nuclear Information System (INIS)

    Some alcohols and diols were oxidized electro-catalytically in a biphasic system using cerium methanesulphonate as mediator. A mixture of methanesulphonic acid solution and benzene was used and aldehydes, ketones and diacids were some of the principal products obtained with yield varying from 27 to 98%. In several cases selectivity was obtained. (author)

  13. The introduction of a double bond on the steroid skeleton - the preparation of enol silyl ether derivatives from vicinal diols

    Czech Academy of Sciences Publication Activity Database

    Marek, Aleš; Klepetářová, Blanka; Elbert, Tomáš

    2011-01-01

    Roč. 76, č. 5 (2011), s. 443-456. ISSN 0010-0765 R&D Projects: GA AV ČR IAA400550801 Institutional research plan: CEZ:AV0Z40550506 Keywords : enol silyl ether * vicinal diol * steroids Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011

  14. THE PHASE BEHAVIOR OF FLUORINATED DIOLS, DIVINYL ADIPATE, AND A FLUORINATED POLYESTER IN SUPERCRITICAL CARBON DIOXIDE. (R828131)

    Science.gov (United States)

    The use of supercritical carbon dioxide as a reaction medium for polyester synthesis is hindered by the low solubility of diols in CO2. However, it has been previously demonstrated that fluorinated compounds can exhibit greater miscibility with carbon dioxide than t...

  15. Boronate Affinity Fluorescent Nanoparticles for Förster Resonance Energy Transfer Inhibition Assay of cis-Diol Biomolecules.

    Science.gov (United States)

    Wang, Shuangshou; Ye, Jin; Li, Xinglin; Liu, Zhen

    2016-05-17

    Förster resonance energy transfer (FRET) has been essential for many applications, in which an appropriate donor-acceptor pair is the key. Traditional dye-to-dye combinations remain the working horses but are rather nonspecifically susceptive to environmental factors (such as ionic strength, pH, oxygen, etc.). Besides, to obtain desired selectivity, functionalization of the donor or acceptor is essential but usually tedious. Herein, we present fluorescent poly(m-aminophenylboronic acid) nanoparticles (poly(mAPBA) NPs) synthesized via a simple procedure and demonstrate a FRET scheme with suppressed environmental effects for the selective sensing of cis-diol biomolecules. The NPs exhibited stable fluorescence properties, resistance to environmental factors, and a Förster distance comparable size, making them ideal donor for FRET applications. By using poly(mAPBA) NPs and adenosine 5'-monophosphate modified graphene oxide (AMP-GO) as a donor and an acceptor, respectively, an environmental effects-suppressed boronate affinity-mediated FRET system was established. The fluorescence of poly(mAPBA) NPs was quenched by AMP-GO while it was restored when a competing cis-diol compounds was present. The FRET system exhibited excellent selectivity and improved sensitivity toward cis-diol compounds. Quantitative inhibition assay of glucose in human serum was demonstrated. As many cis-diol compounds such as sugars and glycoproteins are biologically and clinically significant, the FRET scheme presented herein could find more promising applications. PMID:27089186

  16. Molybdenum-catalyzed conversion of diols and biomass-derived polyols to alkenes using isopropyl alcohol as reductant and solvent

    DEFF Research Database (Denmark)

    Dethlefsen, Johannes Rytter; Lupp, Daniel; Gorfo, Ayele Teshome;

    2015-01-01

    Chemical processes capable of reducing the high oxygen content of biomass-derived polyols are in demand in order to produce renewable substitutes for chemicals of fossil origin. Deoxydehydration (DODH) is an attractive reaction that in a single step transforms a vicinal diol into an alkene, but the...

  17. Facile and Highly Diastereoselective Synthesis of syn- and cis-1,2-Diol Derivatives from Protected alpha-Hydroxy Ketones

    Czech Academy of Sciences Publication Activity Database

    Jahn, Emanuela; Smrček, Jakub; Pohl, Radek; Císařová, I.; Jones, P. G.; Jahn, Ullrich

    2015-01-01

    Roč. 2015, č. 35 (2015), s. 7785-7798. ISSN 1434-193X Grant ostatní: COST(XE) CM1201 Institutional support: RVO:61388963 Keywords : synthetic methods * reduction * diastereoselectivity * diols * ketones Subject RIV: CC - Organic Chemistry Impact factor: 3.065, year: 2014

  18. Enantioselective Synthesis of Vicinal (R,R)-Diols by Saccharomyces cerevisiae Butanediol Dehydrogenase.

    Science.gov (United States)

    Calam, Eduard; González-Roca, Eva; Fernández, M Rosario; Dequin, Sylvie; Parés, Xavier; Virgili, Albert; Biosca, Josep A

    2016-01-01

    Butanediol dehydrogenase (Bdh1p) from Saccharomyces cerevisiae belongs to the superfamily of the medium-chain dehydrogenases and reductases and converts reversibly R-acetoin and S-acetoin to (2R,3R)-2,3-butanediol and meso-2,3-butanediol, respectively. It is specific for NAD(H) as a coenzyme, and it is the main enzyme involved in the last metabolic step leading to (2R,3R)-2,3-butanediol in yeast. In this study, we have used the activity of Bdh1p in different forms-purified enzyme, yeast extracts, permeabilized yeast cells, and as a fusion protein (with yeast formate dehydrogenase, Fdh1p)-to transform several vicinal diketones to the corresponding diols. We have also developed a new variant of the delitto perfetto methodology to place BDH1 under the control of the GAL1 promoter, resulting in a yeast strain that overexpresses butanediol dehydrogenase and formate dehydrogenase activities in the presence of galactose and regenerates NADH in the presence of formate. While the use of purified Bdh1p allows the synthesis of enantiopure (2R,3R)-2,3-butanediol, (2R,3R)-2,3-pentanediol, (2R,3R)-2,3-hexanediol, and (3R,4R)-3,4-hexanediol, the use of the engineered strain (as an extract or as permeabilized cells) yields mixtures of the diols. The production of pure diol stereoisomers has also been achieved by means of a chimeric fusion protein combining Fdh1p and Bdh1p. Finally, we have determined the selectivity of Bdh1p toward the oxidation/reduction of the hydroxyl/ketone groups from (2R,3R)-2,3-pentanediol/2,3-pentanedione and (2R,3R)-2,3-hexanediol/2,3-hexanedione. In conclusion, Bdh1p is an enzyme with biotechnological interest that can be used to synthesize chiral building blocks. A scheme of the favored pathway with the corresponding intermediates is proposed for the Bdh1p reaction. PMID:26729717

  19. 多相对映体选择性环氧化催化剂Mn(salen)/MCM-41的合成%Synthesis of Mn(salen)/MCM-41 Catalyst for Heterogeneous Enantioselective Epoxidation

    Institute of Scientific and Technical Information of China (English)

    向松; 李一梁; 辛勤; 李灿

    2002-01-01

    @@ Enantioselective epoxidation of unfunctionalized olefins is of great importance for synthesis of chiral intermediates in fine chemical production. Chiral salen complexes are excellent catalyst for the epoxidation reaction.

  20. Epoxide migration and pseudo-epoxide migration of 1,6:2,3- and 1,6:3,4-dianhydro-beta-D-hexopyranoses

    Czech Academy of Sciences Publication Activity Database

    Džoganová, Martina; Buděšínský, Miloš; Trnka, T.; Černý, M.

    Chemnitz : Chemnitz University of Technology, 2007. s. 145. [JCF - Frühjahrssymposium /9./. 22.03.2007-24.03.2007, Chemnitz] R&D Projects: GA MZe QF3115 Institutional research plan: CEZ:AV0Z40550506 Keywords : epoxide migration * chair-boat equilibrium * NMR spectroscopy Subject RIV: CC - Organic Chemistry

  1. GC-MS/MS analysis of benzo(a)pyrene by ion trap tandem mass spectrometry

    International Nuclear Information System (INIS)

    The mass spectrometry using an ion trap tandem mass spectrometer has been investigated to find optimum conditions for the analysis of benzo(a)pyrene (3,4-benzpyrene). The applicability to a real soil sample was also investigated to verify the usefulness of the MS/MS (or collision induced dissociation, CID) analysis. The optimum CID condition was 1.5 and 0.45 for the RF excitation voltage and the q value, respectively. For comparison, CID and EI were applied to the analysis of a soil sample. CID analysis was more sensitive than EI analysis of the soil sample. The limit of detection (LOD) of benzo(a)pyrene was 3.18 ng mL-1 and 0.85 ng mL-1 for EI and MS/MS analysis, respectively. The precision at the soil sample for EI and CID showed relative standard deviations of 6.1% and 4.1%, respectively, and the concentrations were 168 μg kg-1 and 162 μg kg-1, respectively

  2. Studies on reactions of cerium(4) reduction with alcohols. Part 3. Reactions of cerium(4) reduction with butane-2,3-diol, butane-1,3-diol and cis-butene-2-diol-1,4 in aqueous solutions of perchloric acid

    International Nuclear Information System (INIS)

    The basic study of the red-ox reaction kinetics of cerium ions -diols-water systems in presence of the perchloric acid is given. Dependence of the various agents and its concentrations on equilibrium constants the complex formation reactions and complex stability are discussed and compared. (B.Cz.)

  3. Interaction of ferroceneboronic acid with diols at aqueous and non-aqueous conditions - signalling and binding abilities of an electrochemical probe for saccharides

    International Nuclear Information System (INIS)

    Highlights: • Electrochemical characterisation of ferroceneboronic acid-diol interactions in non-aqueous solutions. • Elucidation of the signalling process and signalling mechanism of the ferroceneboronic acid upon interaction with diols in aqueous and non-aqueous solutions. • Effect of coordination of boron atom on electrochemistry of ferroceneboronic acid in free and bound forms with diols. - Abstract: Ferroceneboronic acid (FcBA) was employed as a model compound for clarification of binding and signalling properties of molecular probe for saccharides. As the simplest electrochemically active boronic acid, its interactions with diverse diols were studied in homogeneous phase under aqueous and non-aqueous conditions. The FcBA-diol system was examined by cyclic voltammetry resulting in two redox pairs corresponding to free and bound forms of FcBA. Redox potential of the bound form of FcBA was shifted in the cathodic direction in aqueous conditions due to coordination of the hydroxyl group to the boron atom. Oppositely, the anodic shift of the redox potential was observed upon the interaction of FcBA with diols in non-aqueous solvents. The binding properties and signalling mechanism of electrochemically active boronic acids were deduced and the assumptions resulting from the electrochemical behaviour were confirmed by 1H and 11B NMR spectroscopies. The binding constants of the tested diols in aqueous and non-aqueous media were determined and compared

  4. Novel five- to ten-membered organoselenium heterocycles from the selenation of aromatic diols

    OpenAIRE

    Hua, Guoxiong; Fuller, Amy; Slawin, Alexandra M. Z.; Woollins, J. Derek

    2010-01-01

    This work is funded by the EPSRC UK Reaction of Woollins' reagent ― WR , 2,4-bis(phenyl)-1,3-diselenadiphosphetane 2,4-diselenide [{PhP(Se)(μ-Se)}2] ― with aromatic diols in refluxing toluene afforded a series of novel five- to ten-membered phosphorus-selenium heterocycles 1 – 10 with an O–P(Se)–O or O–P(Se)–Se–P(Se)–O or O–P(Se)–O–P(Se)–O linkage in 12–74 % isolated yields. It was found that the diphosphorus species O–P(Se)–Se–P(Se)–O rings could be readily reduced into the monophosphorus...

  5. Isolation and Crystal Structure of 1′,4′-Trans-diol of Abscisic Acid

    Institute of Scientific and Technical Information of China (English)

    WANG Tian-Shan; ZHOU Jin-Yan; TAN Hong

    2006-01-01

    1 ′,4′-Trans-diol of abscisic acid was isolated from botrytis cinerea as a colorless crystal. The molecular and crystal structures have been determined by X-ray diffraction analysis. It crystallizes in orthorhombic system, space group P212121 with a = 6.724(3), b = 17.559(6), c =12.265(2) (A), a = β = y = 90°, V = 1448.1(8) (A)3, Z = 4, Dx = 1.222 g/cm3, F(000) = 576 and μ(MoKa) = 0.087 mm-1. The final R = 0.0628 and wR = 0.1604 for 2501 independent reflections with Rint = 0.0160 and 1679 observed reflections with I >2σ(Ⅰ). There are three intermolecular hydrogen bonds in a unit cell.

  6. A NEW POLYMER-BOUND 1,2-DIOL AS A PROTECTING AGENT FOR SYMMETRICAL DIALDEHYDE

    Institute of Scientific and Technical Information of China (English)

    REN Qisheng; HUANG Wenqiang; ZHAO Fengzhi; Ho Binglin

    1989-01-01

    A novel polymer- bound 1,2 - diol, 3 - polystyrylsulfonyl- 1,2 - propanediol (6) had ben prepared by the reaction of sodium polystyrylsulfinate with allyl bromide, followed by oxidation and. hydrolysis or directly with 3 - chloro - 1,2 - propanediol in the presence of a phase transfer catalyst ,n - tetrabutylammonium iodide. The capacity of resin 6 for terephthaldehyde reached 1.43 mmol/g. The aldehydic groups attached to polymer 6 reacted with hydroxylamine hydrochloride or reduced by sodium borohydride giving p-formylbenzaldoxime (yield:89%)and p-formyl -benzalcohol (yield:73 A % ), respectively. The high yields of these polymer-supported reactions showed that the polymer 6 possessed the effective isolation of its reactive sites.

  7. Soluble epoxide hydrolase deficiency ameliorates acute pancreatitis in mice.

    Science.gov (United States)

    Bettaieb, Ahmed; Morisseau, Christophe; Hammock, Bruce; Haj, Fawaz

    2014-10-01

    Acute pancreatitis (AP) is a frequent gastrointestinal disorder that causes significant morbidity and its incidence has been progressively increasing. AP starts as a local inflammation in the pancreas that often leads to systemic inflammatory response and complications. Soluble epoxide hydrolase (sEH) is a cytosolic enzyme whose inhibition in murine models has beneficial effects in inflammatory diseases, but its significance in AP remains unexplored. To investigate whether sEH may have a causal role in AP we utilized sEH knockout (KO) mice to determine the effects of sEH deficiency on ceruelin- and arginine-induced AP. sEH expression increased at the protein and messenger RNA levels, as well as sEH activity in the early phase of cerulein- and arginine-induced AP in mice. In addition, amylase and lipase levels were lower in cerulein-treated sEH KO mice compared with non-treated controls. Moreover, pancreatic mRNA and serum concentrations of the inflammatory cytokines IL-1ß and IL-6 were lower in sEH KO mice compared with controls. Further, sEH KO mice exhibited decreased cerulein- and arginine-induced NF-?B inflammatory response, MAPKs activation and decreased cell death. These findings demonstrate a novel role for sEH in the progression of cerulein- and arginine-induced AP. PMID:26461340

  8. Discovery of enantioselectivity of urea inhibitors of soluble epoxide hydrolase.

    Science.gov (United States)

    Manickam, Manoj; Pillaiyar, Thanigaimalai; Boggu, PullaReddy; Venkateswararao, Eeda; Jalani, Hitesh B; Kim, Nam-Doo; Lee, Seul Ki; Jeon, Jang Su; Kim, Sang Kyum; Jung, Sang-Hun

    2016-07-19

    Soluble epoxide hydrolase (sEH) hydrolyzes epoxyeicosatrienoic acids (EETs) in the metabolic pathway of arachidonic acid and has been considered as an important therapeutic target for chronic diseases such as hypertension, diabetes and inflammation. Although many urea derivatives are known as sEH inhibitors, the enantioselectivity of the inhibitors is not highlighted in spite of the stereoselective hydrolysis of EETs by sEH. In an effort to explore the importance of enantioselectivity in the urea scaffold, a series of enantiomers with the stereocenter adjacent to the urea nitrogen atom were prepared. The selectivity of enantiomers of 1-(α-alkyl-α-phenylmethyl)-3-(3-phenylpropyl)ureas showed wide range differences up to 125 fold with the low IC50 value up to 13 nM. The S-configuration with planar phenyl and small alkyl groups at α-position is crucial for the activity and selectivity. However, restriction of the free rotation of two α-groups with indan-1-yl or 1,2,3,4-tetrahydronaphthalen-1-yl moiety abolishes the selectivity between the enantiomers, despite the increase in activity up to 13 nM. The hydrophilic group like sulfonamido group at para position of 3-phenylpropyl motif of 1-(α-alkyl-α-phenylmethyl-3-(3-phenylpropyl)urea improves the activity as well as enantiomeric selectivity. All these ureas are proved to be specific inhibitor of sEH without inhibition against mEH. PMID:27092411

  9. Disrupting Dimerization Translocates Soluble Epoxide Hydrolase to Peroxisomes.

    Directory of Open Access Journals (Sweden)

    Jonathan W Nelson

    Full Text Available The epoxyeicosatrienoic acid (EET neutralizing enzyme soluble epoxide hydrolase (sEH is a neuronal enzyme, which has been localized in both the cytosol and peroxisomes. The molecular basis for its dual localization remains unclear as sEH contains a functional peroxisomal targeting sequence (PTS. Recently, a missense polymorphism was identified in human sEH (R287Q that enhances its peroxisomal localization. This same polymorphism has also been shown to generate weaker sEH homo-dimers. Taken together, these observations suggest that dimerization may mask the sEH PTS and prevent peroxisome translocation. In the current study, we test the hypothesis that dimerization is a key regulator of sEH subcellular localization. Specifically, we altered the dimerization state of sEH by introducing substitutions in amino acids responsible for the dimer-stabilizing salt-bridge. Green Fluorescent Protein (GFP fusions of each of mutants were co-transfected into mouse primary cultured cortical neurons together with a PTS-linked red fluorescent protein to constitutively label peroxisomes. Labeled neurons were analyzed using confocal microscopy and co-localization of sEH with peroxisomes was quantified using Pearson's correlation coefficient. We find that dimer-competent sEH constructs preferentially localize to the cytosol, whereas constructs with weakened or disrupted dimerization were preferentially targeted to peroxisomes. We conclude that the sEH dimerization status is a key regulator of its peroxisomal localization.

  10. Heterologous expression, purification, and properties of diol dehydratase, an adenosylcobalamin-dependent enzyme of Klebsiella oxytoca.

    Science.gov (United States)

    Tobimatsu, T; Sakai, T; Hashida, Y; Mizoguchi, N; Miyoshi, S; Toraya, T

    1997-11-01

    Recombinant adenosylcobalamin-dependent diol dehydratase of Klebsiella oxytoca overexpressed in Escherichia coli was purified to homogeneity. The enzyme has a low solubility and was extracted from the crude membrane fraction with 1% Brij 35 in a high recovery. Subsequent chromatography on DEAE-cellulose resulted in 4.9-fold purification of the enzyme in an overall yield of 65%. The enzyme thus obtained showed specific activity comparable to that of the wild-type enzyme of K. oxytoca. The apparent molecular weight determined by nondenaturing gel electrophoresis on a gradient gel was 220,000. The enzyme consists of equimolar amounts of the three subunits with apparent Mr of 60,000 (alpha), 30,000 (beta), and 19,000 (gamma). Therefore, the subunit structure of the enzyme is most likely alpha2beta2gamma2. The recombinant enzyme was also separated into components F and S upon DEAE-cellulose chromatography in the absence of substrate. Components F and S were identified as the beta subunit and alpha2gamma2 complex, respectively. Apparent Km for adenosylcobalamin, 1,2-propanediol, glycerol, and 1,2-ethanediol were 0.83 microM, 0.08 mM, 0.73 mM, and 0.56 mM, respectively. The three genes encoding the subunits of diol dehydratase were overexpressed individually or in various combinations in Escherichia coli. The alpha and gamma subunits mutually required each other for correct folding forming the soluble, active alpha2gamma2 complex (component S). Expression of the beta subunit in a soluble, active form (component F) was promoted by coexpression with both the alpha and gamma subunits, probably by coexistence with component S. These lines of evidence indicate that each subunit mutually affects the folding of the others in this heterooligomer enzyme. PMID:9344474

  11. The waterborne polyurethane dispersions based on polycarbonate diol: Effect of ionic content

    International Nuclear Information System (INIS)

    Three water-based polyurethane dispersions (PUD) were synthesized by modified dispersing procedure using polycarbonate diol (PCD), isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), triethylamine (TEA) and ethylenediamine (EDA). The ionic group content in the polyurethane-ionomer structure was varied by changing the amount of the internal emulsifier, DMPA (4.5, 7.5 and 10 wt.% to the prepolymer weight). The expected structures of obtained materials were confirmed by FTIR spectroscopy. The effect of the DMPA content on the thermal properties of polyurethane films was measured by TGA, DTA, DSC and DMTA methods. Increased DMPA amounts result in the higher hard segment contents and in the increase of the weight loss corresponding to the degradation of the hard segments. The reduction of hard segment content led to the elevated temperature of decomposition and to the decrease of the glass transition temperature and thermoplasticity. The atomic force microscopy (AFM), results indicated that phase separation between hard and soft segment of PUD with higher DMPA content is more significant than of PUD with lower DMPA content. The physico-mechanical properties, such as hardness, adhesion test and gloss of the dried films were also determined considering the effect of DMPA content on coating properties. Highlights: ► Polyurethane dispersions (PUD) were synthesized from polycarbonate diol. ► The effect of the DMPA content on the thermal properties of PUD films was measured. ► The thermal stability of PUD was increased by decreasing the DMPA content. ► Tg values of PUD were increased by increasing ionic content. ► The PUD with the highest content of DMPA showed more significant phase separation confirmed by AFM results

  12. Synthesis and physicochemical properties of epoxidized Tmp trioleate by in situ method

    International Nuclear Information System (INIS)

    Tmp trioleate was initially synthesized via esterification of trimetilolprapane and oleic acid (90%) using 1.5% of H2SO4 as a catalyst. The production of Tmp trioleate was observed at 98% (w/w). The iodine value of Tmp trioleate was analyzed for further reaction of epoxidation. Epoxide was important reaction as an intermediate for preparation of chemical modified lubricants from vegetable oils. Finding the best way of epoxidation process will give high quality for further modification of oil instead of reduce the cost and time for the preparation process during reaction of epoxidation. In this study, the epoxidation of unsaturation Tmp trioleate with peroxyformic acid generated in-situ from hydrogen peroxide 30% in H2O2 with formic acid was studied. 95% conversion to oxygen oxirane content (OOC) ring was obtained. The derivatization showed an improvement of the compound's oxidative stability evidenced from pressurized differential scanning calorimetry (PDSC) data which are 177°C to 200°C. Physicochemical properties showed increasing of temperature of flash point from 280°C to 300°C and viscosity index (VI) from 146 to 154. However, the pour point showed increasing temperature which was −58.81°C to −17.32°C. From the data obtained, these derivatives have shown better performance of lubricity properties. Overall, the data indicates that these performances are compatible to the commercial lubricants

  13. Chemo-enzymatic epoxidation of olefins by carboxylic acid esters and hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Ruesch gen. Klaas, M.; Warwel, S. [Inst. for Biochemistry and Technology of Lipids, H.P. Kaufmanm-Inst., Federal Centre for Cereal, Potato and Lipid Research, Muenster (Germany)

    1998-12-31

    Ethylen and, recently, butadiene can be epoxidized directly with oxygen and for the epoxidation of propylene, the use of heterogeneous transition metals and organic peroxides (Halcon-Process) is the major player. But, beside from those notable exceptions, all other epoxidations, including large ones like the epoxidation of plant oils as PVC-stabilizers (about 200.000 t/year), are carried out with peroxy acids. Because mcpba is far to expensive for most applications, short chain peracids like peracetic acid are used. Being much less stable than mcpba and thus risky handled in large amounts and high concentrations, these peroxy acids were preferably prepared in-situ. However, conventional in-situ formation of peracids has the serious drawback, that a strong acid is necessary to catalyze peroxy acid formation from the carboxylic acid and hydrogen peroxide. The presence of a strong acid in the reaction mixture often results in decreased selectivity because of the formation of undesired by-products by opening of the oxirane ring. Therefore, we propose a new method for epoxidation based on the in-situ preparation of percarboxylic acids from carboxylic acid esters and hydrogen peroxide catalyzed by a commercial, immobilized lipase. (orig.)

  14. Kinetics of the Epoxidation of Geraniol and Model Systems by Dimethyldioxirane

    Directory of Open Access Journals (Sweden)

    B. S. Crow

    2004-02-01

    Full Text Available The mono-epoxidation of geraniol by dimethyldioxirane was carried out invarious solvents. In all cases, the product ratios for the 2,3 and 6,7 mono-epoxides werein agreement with literature values. Kinetic studies were carried out at 23 oC in thefollowing dried solvent systems: acetone (k2 = 1.49 M-1s-1, carbon tetrachloride/acetone(9/1, k2=2.19 M-1s-1, and methanol/acetone (9/1, k2 = 17 M-1s-1. Individual k2 valueswere calculated for epoxidation of the 2,3 and 6,7 positions in geraniol. The non-conjugated diene system was modeled employing two simple independent alkenes:2-methyl-2-pentene and 3-methyl-2-buten-1-ol by determining the respective k2 valuesfor epoxidation in various solvents. The kinetic results for each independent alkeneshowed that the relative reactivity of the two epoxidation sites in geraniol as a function ofsolvent was not simply a summation of the independent alkene systems.

  15. Synthesis and physicochemical properties of epoxidized Tmp trioleate by in situ method

    Energy Technology Data Exchange (ETDEWEB)

    Samidin, Salma; Salimon, Jumat [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2014-09-03

    Tmp trioleate was initially synthesized via esterification of trimetilolprapane and oleic acid (90%) using 1.5% of H{sub 2}SO{sub 4} as a catalyst. The production of Tmp trioleate was observed at 98% (w/w). The iodine value of Tmp trioleate was analyzed for further reaction of epoxidation. Epoxide was important reaction as an intermediate for preparation of chemical modified lubricants from vegetable oils. Finding the best way of epoxidation process will give high quality for further modification of oil instead of reduce the cost and time for the preparation process during reaction of epoxidation. In this study, the epoxidation of unsaturation Tmp trioleate with peroxyformic acid generated in-situ from hydrogen peroxide 30% in H{sub 2}O{sub 2} with formic acid was studied. 95% conversion to oxygen oxirane content (OOC) ring was obtained. The derivatization showed an improvement of the compound's oxidative stability evidenced from pressurized differential scanning calorimetry (PDSC) data which are 177°C to 200°C. Physicochemical properties showed increasing of temperature of flash point from 280°C to 300°C and viscosity index (VI) from 146 to 154. However, the pour point showed increasing temperature which was −58.81°C to −17.32°C. From the data obtained, these derivatives have shown better performance of lubricity properties. Overall, the data indicates that these performances are compatible to the commercial lubricants.

  16. Cycloadditions to Epoxides Catalyzed by GroupIII-V Transition-Metal Complexes

    KAUST Repository

    D'Elia, Valerio

    2015-05-25

    Complexes of groupIII-V transition metals are gaining increasing importance as Lewis acid catalysts for the cycloaddition of dipolarophiles to epoxides. This review examines the latest reports, including homogeneous and heterogeneous applications. The pivotal step for the cycloaddition reactions is the ring opening of the epoxide following activation by the Lewis acid. Two modes of cleavage (C-C versus C-O) have been identified depending primarily on the substitution pattern of the epoxide, with lesser influence observed from the Lewis acid employed. The widely studied cycloaddition of CO2 to epoxides to afford cyclic carbonates (C-O bond cleavage) has been scrutinized in terms of catalytic efficiency and reaction mechanism, showing that unsophisticated complexes of groupIII-V transition metals are excellent molecular catalysts. These metals have been incorporated, as well, in highly performing, recyclable heterogeneous catalysts. Cycloadditions to epoxides with other dipolarophiles (alkynes, imines, indoles) have been conducted with scandium triflate with remarkable performances (C-C bond cleavage). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Atmospheric organic-phase photo-sensitized epoxidation of alkenes by α-dicarbonyls

    Directory of Open Access Journals (Sweden)

    G. Yu

    2012-06-01

    Full Text Available We report a new pathway of epoxide formation in organic phases via catalytic oxidation of alkenes by air with α-dicarbonyls as photo-sensitizers. Epoxide yields as high as 100% in 30 min of exposure to a solar simulator operating at the equivalent of 48.5° zenith angle are observed. The rate constants are proportional to light intensity and inversely proportional to temperature. The reaction rate is 0th order with respect to alkenes, implying that alkenes with small concentrations may rapidly be converted to epoxides in the organic phase. Based on a statistical estimate of α-dicarbonyl concentrations in secondary organic aerosol, we propose that this reaction could be highly effective under ambient conditions: the 0th-order lifetimes of organic-phase alkenes are estimated to be as low as 10 min, significantly shorter than their gas-phase 1st-order lifetimes, which are typically hours to days. The formation of epoxides in organic particles is expected to increase their hygroscopicity and ability to act as cloud condensation nuclei. Epoxides in deliquesced particles can subsequently form polyalcohols, oligomers, organosulphates and organonitrates, increasing the organic mass in the atmospheric waters.

  18. Electron-beam curing of epoxide resins in the presence of tetrahydrofuran

    International Nuclear Information System (INIS)

    Epoxide resins are widely utilized in the fields of coating, adhesion, lamination, casting and others. The cationic polymerization of epoxide resins containing onium salts can be initiated by ultraviolet and electron beam irradiation. Radiation induced cationic curing begins to attract much interest because the curing proceeds smoothly in the air. Tetrahydrofuran (THF) is a good solvent for epoxide resins. It was reported that the cationic polymerization of THF occurred with the protonic acid generated from triphenyl sulfonium salt by UV irradiation. Therefore, it is expected that THF is used as a reactive diluent for the radiation curing of epoxide resins. In the present work, the mixtures of bisphenol A type epoxide resin and THF containing a small amount of onium salt were irradiated with electron beam, and the dynamic mechanical and thermal properties of the electron beam-cured products were investigated. The materials used, the irradiation with the electron beam from a Van de Graaff accelerator, the determination of gel content, infrared spectrum studies, and the measurement of dynamic mechanical properties and thermogravimetry are described, and the results are reported. (K.I.)

  19. Synthesis of a precursor for the preparation of 9 alpha,11 alpha-tritiated 5 alpha-androstane-3 alpha,17 beta-diol 17-glucuronide

    International Nuclear Information System (INIS)

    Starting from 11 beta-hydroxytestosterone, the synthesis of a strategic precursor, C-9 (11) unsaturated 5 alpha-androstane-3 alpha, 17 beta-diol 17-glucuronide (9a), for the preparation of 9 alpha,11 alpha-tritiated 5 alpha-androstane-3 alpha, 17 beta-diol 17-glucuronide has been achieved. The authors optimized the reaction conditions for catalytic reduction employing hydrogen and subsequent base hydrolysis followed by purification on Amberlite XAD-2 resin to obtain the saturated 5 alpha-androstane-3 alpha, 17 beta-diol 17-glucuronide

  20. MUTAGENICITY OF BENZO(A)PYRENE METABOLITES GENERATED ON THE ISOLATED PERFUSED LUNG FOLLOWING PARTICULATE EXPOSURE (JOURNAL VERSION)

    Science.gov (United States)

    The isolated perfused rabbit lung (IPL) is being used to study the effects of particulate exposure on the pulmonary metabolism of benzo(a)pyrene (BaP). Pasturealla-free New Zealand white rabbits were treated intraperitoneally with BaP prior to kill. The isolated lungs were then a...

  1. Benzo[a]pyrene co-metabolism in the presence of plant root extracts and exudates: Implications for phytoremediation

    International Nuclear Information System (INIS)

    Benzo[a]pyrene, a high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH) was removed from solution by Sphingomonas yanoikuyae JAR02 while growing on root products as a primary carbon and energy source. Plant root extracts of osage orange (Maclura pomifera), hybrid willow (Salix albaxmatsudana), or kou (Cordia subcordata), or plant root exudates of white mulberry (Morus alba) supported 15-20% benzo[a]pyrene removal over 24 h that was similar to a succinate grown culture and an unfed acetonitrile control. No differences were observed between the different root products tested. Mineralization of 14C-7-benzo[a]pyrene by S. yanoikuyae JAR02 yielded 0.2 to 0.3% 14CO2 when grown with plant root products. Collectively, these observations were consistent with field observations of enhanced phytoremediation of HMW PAH and corroborated the hypothesis that co-metabolism may be a plant/microbe interaction important to rhizoremediation. However, degradation and mineralization was much less for root product-exposed cultures than salicylate-induced cultures, and suggested the rhizosphere may not be an optimal environment for HMW PAH degradation by Sphingomonas yanoikuyae JAR02. - Bacterial benzo[a]pyrene cometabolism, a plant-microbe interaction affecting polycyclic aromatic hydrocarbon phytoremediation was demonstrated with Sphingomonas yanoikuyae JAR02 that utilized plant root extracts and exudates as primary substrates

  2. Effects of Benzo[a]pyrene on DNA Damage and Histological alterations in Gonad of Scallop Chlamys farreri

    OpenAIRE

    Jing-Jing, Miao; Lu-Qing, Pan; Jing, Liu; Lin, Zhang

    2008-01-01

    Effects of Benzo[a]pyrene on DNA Damage and Histological alterations in Gonad of Scallop Chlamys farreri correspondence: Corresponding author. (Lu-qing, Pan) (Lu-qing, Pan) The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China - No. 5--> , Yushan Road--> , Qingdao--> - CHINA (Jing-jing, Miao) The Key Laboratory of Mariculture, Ministry of Education, Ocean University ...

  3. METABOLISM AND DNA (DEOXYRIBONUCLEIC ACID) BINDING OF BENZO(A)PYRENE IN CULTURED HUMAN BLADDER AND BRONCHUS

    Science.gov (United States)

    The metabolism of benzo(a)pyrene (BP) was examined in ex-plant cultures of human bladder and bronchus. Three-day cultures were exposed to radiolabeled BP for 24 h, and the metabolism was determined by analysis of the level of binding of reactive metabolites to DNA, and by the rel...

  4. Epoxidation of alkenes through oxygen activation over a bifunctional CuO/Al2O3 catalyst.

    Science.gov (United States)

    Scotti, Nicola; Ravasio, Nicoletta; Zaccheria, Federica; Psaro, Rinaldo; Evangelisti, Claudio

    2013-03-01

    The epoxidation of alkenes was carried out over a CuO/Al(2)O(3) catalyst using cumene as an oxygen carrier, through a one-pot reaction, giving high conversion and selectivity with different substrates. Trans-β-methylstyrene gave the corresponding epoxide in 95% yield after 3 h. PMID:23358661

  5. NMR study of the epoxidation of liquid hydrolyzed poly-butadiene and meta-chloro-per-benzoic acid

    International Nuclear Information System (INIS)

    This work presents a study concerning the selectivity of the different configurations of the double bond present in liquid hydrolyzed poly-butadiene towards the epoxidation reaction with meta-chloro-per-benzoic acid through hydrogen-1, carbon-13 NMR aiming the production of new materials, varying the epoxidation level

  6. Evidence for the powerful catalytic ability of imidozirconocene complex from its epoxide ring cleavage reactions - A DFT mechanistic view

    Indian Academy of Sciences (India)

    Dhurairajan Senthilnathan; Rajadurai Vijay Solomon; Ponnambalam Venuvanalingam

    2012-01-01

    Imidozirconocene complex is known for its bifunctional reactivity and catalytic ability and this complex mediates ring cleavage of epoxides. Cyclooctene oxide (1) Norbornene oxide (2) and 2,5-dimethyl cyclohexene oxide (3) undergo ring cleavage in the presence of imidozirconocene complex. Epoxide 1 has accessible -hydrogens (type I) while epoxide 2 and 3 do not have them (type II). Normally type I epoxides undergo elimination while type II epoxides prefer insertion. All the insertion reactions lead to five-membered metallacycle formation and elimination results in thermodynamically stable allyl-alkoxy product. The insertion is a two-step process following either diradical or zwitterionic pathway, while elimination is a one-step concerted reaction. DFT (density functional theory) modelling of these reactions at B3LYP/LANL2DZ level show that epoxide 1 undergoes elimination in agreement with experiment. However, calculations indicate that epoxide (2) proceeds through diradical intermediate in contrast to experimental observations. Surprisingly, epoxide (3) that has both the positions blocked by methyl groups undergoes elimination rather than insertion. AIM and EDA analyses offer further insights on the reaction mechanism and bifunctional reactivity of imidozirconozene complex.

  7. Epoxidized natural rubber toughened aqueous resole type liquefied EFB resin: Physical and chemical characterization

    Science.gov (United States)

    Amran, Umar Adli; Zakaria, Sarani; Chia, Chin Hua

    2013-11-01

    A preliminary study on the reaction between aqueous resole type resinified liquefied palm oil empty fruit bunches fibres (RLEFB) with epoxidized natural rubber (ENR). Liquefaction of empty fruit bunches (EFB) is carried out at different ratio of phenol to EFB (P:EFB). Resole type phenolic resin is prepared using sodium hydroxide (NaOH) as the catalyst with the ratio of liquefied EFB (LEFB) to formaldehyde (LEFB:F) of 1:1.8. 50% epoxidation of epoxidized natural rubber (ENR-50) is used to react with resole resin by mixing with ENR with aqueous resole resin. The cured resin is characterized with FT-IR and SEM. Aqueous system have been found to be unsuitable medium in the reaction between resin and ENR. This system produced a highly porous product when RLEFB/ENR resin is cured.

  8. Copper nanocrystal plane effect on stereoselectivity of catalytic deoxygenation of aromatic epoxides.

    Science.gov (United States)

    Xiao, Bin; Niu, Zhiqiang; Wang, Yang-Gang; Jia, Wei; Shang, Jian; Zhang, Lan; Wang, Dingsheng; Fu, Yao; Zeng, Jie; He, Wei; Wu, Kai; Li, Jun; Yang, Jinlong; Liu, Lei; Li, Yadong

    2015-03-25

    Previous studies have shown that crystal planes of heterogeneous catalysts could display enhanced activity, such that higher turnover or chemoselectivity could be achieved. Here we report an example where the reaction stereoselectivity was significantly affected by the catalyst crystal planes. In copper-catalyzed deoxygenation reaction of aromatic epoxides, copper cubes, wires, and plates gave the olefin products with different cis/trans selectivities, whereas homogeneous copper catalysts showed poor selectivity. Scanning tunneling microscope and density functional theory studies revealed that the different adsorption mode and higher adsorption strength of epoxide oxygen on Cu{100} plane were responsible for the observed variation of selectivity. The copper-catalyzed deoxygenation reaction provided new practical access to cis-olefins from readily available aromatic epoxides. Our work also indicated that nanocrystal catalysts may provide useful stereochemical control in organic reactions. PMID:25778784

  9. Radiation-chemical solidification of compositions based on modified epoxide resins

    International Nuclear Information System (INIS)

    Possibilites of obtaining radiation-solidified compositions on the base of EhD-20 epoxide resin where the greatest part of epoxide groups is replaced by methacrylates, are studied. Coatings on the base of epoxide groups have been solidified with γ-rays and accelerated electrons in the atmosphere of the inert gas (electron energy 600 keV, radiation intensity 9.8 Mrad/min). It is shown that dimethylaminoethylmethacrylate is a catalyst of radiation solidification. Its optimum quantity in compositions is 5%. The dose neccessary for solidification decreases considerably (from 5-7 Mrad to 2 Mrad) and gel fraction maximum content increases. Physical and chemical properties of the above coating on the metal are investigated

  10. Genetically reduced soluble epoxide hydrolase activity and risk of stroke and other cardiovascular disease

    DEFF Research Database (Denmark)

    Lee, Julie; Dahl, Morten; Grande, Peer; Tybjaerg-Hansen, Anne; Nordestgaard, Børge G

    2010-01-01

    BACKGROUND AND PURPOSE: The development of stroke has been linked to lowered levels of epoxyeicosatrienoic acids in the cerebral microvasculature. These substances are metabolized by the enzyme-soluble epoxide hydrolase encoded by the EPHX2 gene. We tested whether genetically reduced soluble...... epoxide hydrolase activity is associated with risk of ischemic stroke, myocardial infarction, and ischemic heart disease. METHODS: We genotyped participants from the Copenhagen City Heart Study (n=10 352), the Copenhagen General Population Study (n=26 042), the Copenhagen Carotid Stroke Study (n=398 cases......=0.08 to 1.00). Similar results were obtained for myocardial infarction and ischemic heart disease in the 3 studies. CONCLUSIONS: Our results show with significant power that genetically reduced soluble epoxide hydrolase activity is not a major risk factor for ischemic stroke, myocardial infarction...

  11. The separation and synthesis of lipidic 1,2- and 1,3-diols from natural phenolic lipids for the complexation and recovery of boron.

    Science.gov (United States)

    Tyman, John H P; Mehet, Satinderjit K

    2003-12-01

    A study has been made of the semi-synthesis of 1,3-diols (anacardic alcohols) from natural phenolic lipid resources from Anacardium occidentale and Anacardium giganteum which have given C15 and C11 derivatives, respectively. An isomeric 1,3-diol (isoanacardic alcohol) has been obtained from cardanol separated from technical cashew nut-shell liquid. Homologous 1,3-diols have been synthesised from a range of synthetic 2-alkyl-, 3-alkyl- and 4-alkylphenols and from 6-alkylsalicylic acids. The natural 1,2-diol, urushiol, from Rhus vernicifera has been purified. All these lipidic compounds have been studied for their complexation and the potential recovery of boron as boric acid. PMID:14623453

  12. Long chain diol index (LDI) as an organic-based sea surface temperature proxy in the Korean East Sea (NW Pacific)

    Science.gov (United States)

    Gal, Jong-Ku; Kim, Jung-Hyun; Kang, Su-Jin; Lee, Dong-Hun; Shin, Kyung-Hoon

    2016-04-01

    Long chain diol index (LDI) was introduced as an organic-based sea surface temperature (SST) proxy. LDI is expressed as the C30 1,15-diol abundance relative to those of C28 1,13-, C30 1,13- and C30 1,15-diols. There were a few studies which accessed the potential of LDI based on the culture, core top sediments, suspended particulate organic matters, and down-core sediments. However it is still unknown about the source of the diols and robustness as the SST proxy in the various marine environments. In the current study, we examined the applicability of the LDI in the East Sea of Korea where productivity and thus sedimentation rates are high. We will compare the LDI data with those of alkenone-based UK'37 by analyzing two multicores covering the last 100 year.

  13. Unusual Regioselectivity in the Opening of Epoxides by Carboxylic Acid Enediolates

    Directory of Open Access Journals (Sweden)

    José Segura

    2008-06-01

    Full Text Available Addition of carboxylic acid dianions appears to be a potential alternative to the use of aluminium enolates for nucleophilic ring opening of epoxides. These conditions require the use of a sub-stoichiometric amount of amine (10% mol for dianion generation and the previous activation of the epoxide with LiCl. Yields are good, with high regioselectivity, but the use of styrene oxide led, unexpectedly, to a mixture resulting from the attack on both the primary and secondary carbon atoms. Generally, a low diastereoselectivity is seen on attack at the primary center, however only one diastereoisomer was obtained from attack to the secondary carbon of the styrene oxide.

  14. Miscibility study of hexanoyl chitosan in blend with epoxidized natural rubber by viscometric analysis

    Science.gov (United States)

    Jamal, Asheila; Chan, C. H.; Muhammad, F. H.; Winie, Tan

    2015-08-01

    Miscibility of blends of hexanoyl chitosan and epoxidized natural rubber with 25 mol% epoxidation level (ENR25) was investigated by dilute solution viscometry (DSV). Experimental results obey the Huggins' equation in the concentration range under investigation. Intrinsic viscosities are found to vary linearly with blend composition. The difference between experimental and ideal Huggins coefficients, κ =K12-√{K1ṡK2 } is proposed to evaluate the miscibility behavior of the blends. Negative deviations from the ideal behavior indicated immiscibility between hexanoyl chitosan and ENR25.

  15. Asymmetric epoxidation of allylic alcohols catalyzed by vanadium-binaphthylbishydroxamic Acid complex.

    Science.gov (United States)

    Noji, Masahiro; Kobayashi, Toshihiro; Uechi, Yuria; Kikuchi, Asami; Kondo, Hisako; Sugiyama, Shigeo; Ishii, Keitaro

    2015-03-20

    A vanadium-binaphthylbishydroxamic acid (BBHA) complex-catalyzed asymmetric epoxidation of allylic alcohols is described. The optically active binaphthyl-based ligands BBHA 2a and 2b were synthesized from (S)-1,1'-binaphthyl-2,2'-dicarboxylic acid and N-substituted-O-trimethylsilyl (TMS)-protected hydroxylamines via a one-pot, three-step procedure. The epoxidations of 2,3,3-trisubstituted allylic alcohols using the vanadium complex of 2a were easily performed in toluene with a TBHP water solution to afford (2R)-epoxy alcohols in good to excellent enantioselectivities. PMID:25714329

  16. Characterization Study of EPDM Rubber Vulcanized by Gamma Radiation in The Presence of Epoxidized Soybean Oil

    International Nuclear Information System (INIS)

    Composites based on ethylene-propylene-diene rubber (EPDM) were prepared. EPDM loaded with 40 phr fumed silica in the presence of different concentrations of epoxidized soybean oil ranging between 4 and 8 phr. The composites were subjected to various gamma irradiation doses up to 200 kGy. The physical, mechanical and thermal properties of rubber composition as a function of irradiation dose were investigated. Gamma irradiation led to a significant improvement in the properties of the all compositions. Besides, an improvement in the mechanical properties was attained with the addition of 4 phr of epoxidized soybean oil.

  17. Soybean epoxide production with in situ peracetic acid using homogeneous catalysis

    Directory of Open Access Journals (Sweden)

    Luis Alejandro Boyacá Mendivelso

    2010-05-01

    Full Text Available Using vegetable oils has become an excellent option for petrochemical product substitution. The epoxides obtained from such oils have wide applications as plastifiers and PVC stabilisers and as raw material in polyol synthesis for the polyurethane industry. This paper presents soybean oil epoxidation using a homogeneous catalyst in a well-mixed, stirred reactor being operated in iso- thermal conditions. The best result achieved was a 6.4% oxyrane oxygen content using hydrogen peroxide (25% molar excess, a- cetic acid (5% p/p and sulphuric acid (2% p/p concentrations at 80°C.

  18. Synthesis of phytuberin. 4-endo-tet acid-catalyzed cyclization of alpha-hydroxy epoxides.

    Science.gov (United States)

    Prangé, Thierry; Rodríguez, María S; Suárez, Ernesto

    2003-05-30

    The total synthesis of phytuberin, a phytoalexin of the Solanum genus, from (-)-alpha-santonin is reported. The key steps include (a) reductive cleavage of the C-O bond of the gamma-lactone with concomitant protection of the C1 double bond, (b) Sharpless stereocontrolled hydroxy-assisted epoxidation of allylic alcohol 6 and simultaneous deprotection of the C1 double bond, (c) a rare 4-endo-tet acid-catalyzed cyclization of an alpha-hydroxy epoxide, and (d) an unprecedented 4-exo selenocyclization of a homoallylic alcohol. PMID:12762747

  19. Green chemistry: Efficient epoxides ring-opening with 1-butanol under microwave irradiation

    International Nuclear Information System (INIS)

    Two activated carbons treated with mineral acids (HNO3 and sulfonitric mixture) have been tested as acid catalysts in the epoxides (1,2-epoxyhexane and styrene oxide) ring-opening reaction with 1-butanol under microwave (MW) irradiation. The mayor obtained product is that resulting of the alcohol addition to the most substituted carbon in the epoxide ring. The most active catalyst is that treated with sulfonitric mixture. The use of a MW oven allows achieving to the complete conversion of styrene oxide in only 2 min

  20. Green chemistry: Efficient epoxides ring-opening with 1-butanol under microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Vidal, Jesus A. [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Extremadura, Campus Universitario, Avda. de Elvas, s/n, E-06071-Badajoz (Spain); Duran-Valle, Carlos J. [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Extremadura, Campus Universitario, Avda. de Elvas, s/n, E-06071-Badajoz (Spain)]. E-mail: carlosdv@unex.es; Ferrera-Escudero, Santiago [Departamento de Quimica Inorganica y Quimica Tecnica, Universidad Nacional de Educacion a Distancia, C/Senda del Rey, 9, E-28040 Madrid (Spain)

    2006-06-30

    Two activated carbons treated with mineral acids (HNO{sub 3} and sulfonitric mixture) have been tested as acid catalysts in the epoxides (1,2-epoxyhexane and styrene oxide) ring-opening reaction with 1-butanol under microwave (MW) irradiation. The mayor obtained product is that resulting of the alcohol addition to the most substituted carbon in the epoxide ring. The most active catalyst is that treated with sulfonitric mixture. The use of a MW oven allows achieving to the complete conversion of styrene oxide in only 2 min.

  1. Role of soluble epoxide hydrolase in the sex-specific vascular response to cerebral ischemia

    OpenAIRE

    Zhang, Wenri; Iliff, Jeffrey J.; Campbell, Caitlyn J; Wang, Ruikang K.; Hurn, Patricia D.; Alkayed, Nabil J.

    2009-01-01

    Soluble epoxide hydrolase (sEH), a key enzyme in the metabolism of vasodilator eicosanoids called epoxyeicosatrienoic acids (EETs), is sexually dimorphic and suppressed by estrogen. We determined if the sex difference in blood flow during focal cerebral ischemia is linked to sEH. Soluble epoxide hydrolase expression in brain, hydrolase activity in cerebral vessels, and plasma 14,15-dihydroxyeicosatrienoic acid (14,15-DHET) were determined in male and female wild-type (WT) and sEH knockout (sE...

  2. Synthesis of Marine Polycyclic Polyethers via Endo-Selective Epoxide-Opening Cascades

    Directory of Open Access Journals (Sweden)

    Timothy F. Jamison

    2010-03-01

    Full Text Available The proposed biosynthetic pathways to ladder polyethers of polyketide origin and oxasqualenoids of terpenoid origin share a dramatic epoxide-opening cascade as a key step. Polycyclic structures generated in these biosynthetic pathways display biological effects ranging from potentially therapeutic properties to extreme lethality. Much of the structural complexity of ladder polyether and oxasqualenoid natural products can be traced to these hypothesized cascades. In this review we summarize how such epoxide-opening cascade reactions have been used in the synthesis of ladder polyethers and oxasqualenoid natural products.

  3. Bonding two surfaces by exposing to actinic radiation an epoxide liquid composition

    International Nuclear Information System (INIS)

    A method for preparing a film adhesive from an epoxide resin is described. A liquid containing an epoxide resin and a photopolymerizable compound is polymerized to form a solid continuous film by exposure to actinide radiation. A catalyst can be used but no thermal crosslinking should be allowed to occur. The film so obtained is used to bond surfaces together by the application of heat and pressure. The period of heating can be very short, as there need be no solvent to evaporate and the films need not be thick, typically 20 to 250 μm. (O.T.)

  4. The selection reaction of homogeneous catalyst in soy-epoxide hydroxylation

    Science.gov (United States)

    Elvistia Firdaus, Flora

    2014-04-01

    Hydroxylation reaction of soy-epoxide has resulted soy-polyol; a prepolymeric material for polyurethane. The conversion and selectivity of soy-epoxide butanol based to hydroxylation was found higher than soy-ethylene glycol (EG) based. These reactions were performed by sulfur acid which commonly known as homogeneous catalyst. Conversion and selectivity of homogeneous catalyst compared to bentonite; a heteregeneous catalyst was lower as in fact the mixtures were more viscous. The catalysis were significantly effected to cell morphology. Foams were conducted by heterogeneous catalyst resulted an irregular form of windows while homogeneous catalyst are more ordered.

  5. Cyclic interconversion of vitamin K1 and vitamin K1 2,3-epoxide in man.

    OpenAIRE

    Bechtold, H; Trenk, D; Meinertz, T; Rowland, M; Jähnchen, E.

    1983-01-01

    The disposition of a single intravenous bolus dose of 10 mg vitamin K1 and vitamin K1-2,3-epoxide were studied in two healthy subjects without and with 12 h pretreatment dose of phenprocoumon (0.4 mg/kg). For each compound administered alone the plasma concentration-time profile was adequately fitted by a biexponential equation, with an average terminal half-life of 2.0 and 1.15 h for the administered vitamin K and its 2,3-epoxide respectively. While vitamin K1 was measurable in plasma follow...

  6. Asbestos-catalyzed oxidation of benzo(a)pyrene by superoxide-peroxidized microsomes

    International Nuclear Information System (INIS)

    Asbestos and benzo(a)pyrene [B(a)P] are ubiquitous in our environment and both are recognized as causal factors for cancer in man and animals. In vitro studies showed a synergism in morphological transformation of mammalian cells treated with asbestos and B(a)P. It has been shown that asbestos can mediate lipid peroxidation and that iron cations might be involved in the catalytic activity of asbestos fibers. A previous study of B(a)P metabolism by microsomes showed that peroxidative conditions change the balance between activation and deactivation of B(a)P and demonstrated that catalytically active iron can play a role in this process. The present investigation examines the effect of asbestos on oxidation of B(a)P by superoxide - peroxidized microsomes in vitro

  7. Liquid chromatographic determination of benzo(a)pyrene in total particulate matter of cigarette smoke

    Energy Technology Data Exchange (ETDEWEB)

    Tomkins, B.A.; Jenkins, R.A.; Griest, W.H.; Reagan, R.R.; Holladay, S.K.

    1985-09-01

    The benzo(a)pyrene (BaP) delivery of reference and commercially available tobacco cigarettes, as well as reference and placebo marijuana cigarettes, is determined using a sequential liquid chromatographic/liquid chromatographic procedure. The total particulate matter of sample cigarette smoke is collected using a Cambridge filter pad, which is ultrasonically extracted with acetone. The resulting extract is filtered, then fractionated using semipreparative-scale normal phase liquid chromatography (LC). Quantitative determination is achieved using analytical-scale reverse phase LC equipped with a fluorescence detector. The method is precise (+/- 10-15% relative standard deviation) and yields 85% or better BaP recovery at the ng/cig. level. A single pad may be analyzed in 8 person-hours, while a more typical lot of 12 pads (6 pads each for 2 cigarette brands) may be analyzed in 10 person-days.

  8. Chlorophyll catalyse the photo-transformation of carcinogenic benzo[a]pyrene in water

    Science.gov (United States)

    Luo, Lijuan; Lai, Xueying; Chen, Baowei; Lin, Li; Fang, Ling; Tam, Nora F. Y.; Luan, Tiangang

    2015-08-01

    Algal blooms cause great damage to water quality and aquaculture. However, this study showed that dead algal cells and chlorophyll could accelerate the photo-transformation of benzo[a]pyrene (BaP), a ubiquitous and persistent pollutant with potently mutagenic and carcinogenic toxicities, under visible light irradiation. Chlorophyll was found to be the major active substance in dead algal cells, and generated a high level of singlet oxygen to catalyse the photo-transformation of BaP. According to various BaP metabolites formed, the degradation mechanism was proposed as that chlorophyll in dead algal cells photo-oxidized BaP to quinones via photocatalytic generation of singlet oxygen. The results provided a good insight into the role of chlorophyll in the photo-transformation of organic contaminants and could be a possible remediation strategy of organic pollutants in natural environment.

  9. Base substitution mutations induced by metabolically activated aflatoxin B1.

    Science.gov (United States)

    Foster, P L; Eisenstadt, E; Miller, J H

    1983-05-01

    We have determined the base substitutions generated by metabolically activated aflatoxin B1 in the lacI gene of a uvrB- strain of Escherichia coli. By monitoring over 70 different nonsense mutation sites, we show that activated aflatoxin B1 specifically induced GxC leads to TxA transversions. One possible pathway leading to this base change involves depurination at guanine residues. We consider this mechanism of mutagenesis in the light of our other findings that the carcinogens benzo[a]pyrene diol epoxide and N-acetoxyacetylaminofluorene also specifically induce GxC leads to TxA transversions. PMID:6405385

  10. Ring Expansion of Cyclic 1,2-Diols to form Medium Sized Rings via Ruthenium Catalyzed Transfer Hydrogenative [4+2] Cycloaddition

    OpenAIRE

    Kasun, Zachary A.; Geary, Laina M.; Krische, Michael J.

    2014-01-01

    A new method for the ring expansion of cyclic diols is described. Using improved conditions for the ruthenium(0) catalyzed cycloaddition of cyclic 1,2-diols with 1,3-dienes, fused [n.4.0] bicycles 3a–3r (n = 3–6) are formed, which upon exposure to iodosobenzene diacetate engage in oxidative cleavage to form the 9–12 membered rings 4a–4r.

  11. Sustainable Pathways to Pyrroles through Iron-Catalyzed N-Heterocyclization from Unsaturated Diols and Primary Amines.

    Science.gov (United States)

    Yan, Tao; Barta, Katalin

    2016-09-01

    Pyrroles are prominent scaffolds in pharmaceutically active compounds and play an important role in medicinal chemistry. Therefore, the development of new, atom-economic, and sustainable catalytic strategies to obtain these moieties is highly desired. Direct catalytic pathways that utilize readily available alcohol substrates have been recently established; however, these approaches rely on the use of noble metals such as ruthenium or iridium. Here, we report on the direct synthesis of pyrroles using a catalyst based on the earth-abundant and inexpensive iron. The method uses 2-butyne-1,4-diol or 2-butene-1,4-diol that can be directly coupled with anilines, benzyl amines, and aliphatic amines to obtain a variety of N-substituted pyrroles in moderate-to-excellent isolated yields. PMID:27493031

  12. [Diol column as stationary phase for high performance liquid chromatographic analysis of carbohydrates in drinks with evaporative light scattering detection].

    Science.gov (United States)

    Wei, Y; Guo, L; Ding, M Y

    2001-11-01

    A high performance liquid chromatographic method with a diol column and evaporative light scattering detector (ELSD) was established for the direct analysis of fructose, glucose, sucrose, maltose and raffinose in mixture. A separation column (Lichrospher 100 Diol, 250 mm x 4.0 mm i.d., 5 microns, Hewlett-Packard, USA) and a guard column (Zorbax Rx-SIL, 12.5 mm x 4.6 mm i.d., 5 microns) were used. The mobile phase was a mixture of dichloromethane-methanol (3.2:1, volume ratio). Regression equations revealed linear relationship (correlation coefficients: 0.995-0.999) between the mass of carbohydrates injected and the peak area of carbohydrates detected by ELSD. The detection limits of ELSD (S/N = 3) were about 0.20 microgram for all carbohydrates. This system could be used for the routine analysis of simple carbohydrates in some common drinks on market. PMID:12545463

  13. Human Vitamin K 2,3-Epoxide Reductase Complex Subunit 1-like 1 (VKORC1L1) Mediates Vitamin K-dependent Intracellular Antioxidant Function*

    OpenAIRE

    Westhofen, Philipp; Watzka, Matthias; Marinova, Milka; Hass, Moritz; Kirfel, Gregor; Müller, Jens; Carville G. Bevans; Müller, Clemens R; Oldenburg, Johannes

    2011-01-01

    Human vitamin K 2,3-epoxide reductase complex subunit 1-like 1 (VKORC1L1), expressed in HEK 293T cells and localized exclusively to membranes of the endoplasmic reticulum, was found to support both vitamin K 2,3-epoxide reductase (VKOR) and vitamin K reductase enzymatic activities. Michaelis-Menten kinetic parameters for dithiothreitol-driven VKOR activity were: Km (μm) = 4.15 (vitamin K1 epoxide) and 11.24 (vitamin K2 epoxide); Vmax (nmol·mg−1·hr−1) = 2.57 (vitamin K1 epoxide) and 13.46 (vit...

  14. Synthesis of bio-based thermoplastic polyurethane elastomers containing isosorbide and polycarbonate diol and their biocompatible properties.

    OpenAIRE

    Oh, S. Y.; Kang, M. S.; Knowles, J. C.; Gong, M. S.

    2015-01-01

    A new family of highly elastic polyurethanes (PUs) partially based on renewable isosorbide were prepared by reacting hexamethylene diisocyanate with a various ratios of isosorbide and polycarbonate diol 2000 (PCD) via a one-step bulk condensation polymerization without catalyst. The influence of the isorsorbide/PCD ratio on the properties of the PU was evaluated. The successful synthesis of the PUs was confirmed by Fourier transform-infrared spectroscopy and (1)H nuclear magnetic resonance. T...

  15. Purification of a vitamin K epoxide reductase that catalyzes conversion of vitamin K 2,3-epoxide to 3-hydroxy-2-methyl-3-phytyl-2,3-dihydronaphthoquinone.

    OpenAIRE

    Mukharji, I; Silverman, R B

    1985-01-01

    An enzyme from bovine liver microsomes that catalyzes the reduction of vitamin K 2,3-epoxide to 2- and 3-hydroxy-2-methyl-3-phytyl-2,3-dihydronaphthoquinone was purified 1152-fold to apparent homogeneity. Microsomes were solubilized with 3-[3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), and the enzyme was purified by chromatography on PBE-94 ion exchanger, hydroxylapatite, and DEAE-cellulose, and then gel filtration on Sephacryl S-200. The homogeneity of the final preparation ...

  16. Epoxide migration and pseudo-epoxide migration of 1,6:2,3- and 1,6:3,4-dianhydro-beta-D-hexopyranoses

    Czech Academy of Sciences Publication Activity Database

    Džoganová, Martina; Buděšínský, Miloš; Trnka, T.; Černý, M.

    Praha : Institute of Chemical Technology, 2007 - (Moravcová, J.; Křen, V.). s. 24 ISBN 978-80-7080-006-5. [Cukrblik 2007. Current Chemistry and Biochemistry of Saccharides. 20.04.2007, Praha] R&D Projects: GA MZe QF3115; GA AV ČR KAN200520703 Institutional research plan: CEZ:AV0Z40550506 Keywords : epoxide migration * carbohydrates * NMR spectroscopy Subject RIV: CC - Organic Chemistry

  17. Effect of various chemicals on the metabolism of benzo(a)pyrene by cultured rat colon

    DEFF Research Database (Denmark)

    1977-01-01

    hydroxylase (AHH) activity and binding levels of BP to macromolecules were higher in the descending colon when compared to other segments. The major metabolites of BP, extractable with ethylacetate, were quinones, tetrols, 7,8-diol and a peak containing 9,10-dihydroxy-9,10-dihydrobenzo(a)pyrene and 7......,8,9-trihydroxy-7,8-dihydrobenzo(a)pyrene. The binding levels of BP to DNA and protein in the explant was lowered by co-incubation with 7,8-benzoflavone (7,8-BF) (3.6 and 18.0 micron), a known inhibitor of AHH, and with disulfiram (100 micron), an anti-oxidant. The absence of vitamin A in the media also resulted...

  18. Juvenile hormone diol kinase, a calcium-binding protein with kinase activity, from the silkworm, Bombyx mori.

    Science.gov (United States)

    Li, Sheng; Zhang, Qi-Rui; Xu, Wei-Hua; Schooley, David A

    2005-11-01

    Juvenile hormone (JH) diol kinase (JHDK) is an important enzyme involved in the JH degradation pathway. Bombyx mori (Bommo)-JHDK cDNA (637bp) contains an open reading frame encoding a 183-amino acid protein, which reveals a high degree of identity to the two previously reported JHDKs. JHDK is similar to GTP-binding proteins with three conserved sequence elements involved in purine nucleotide binding, contains eight alpha-helices and three EF-hand motifs, and resembles the three-dimensional model of 2SCP and some other calcium-binding proteins. The Bommo-JHDK gene has only a single copy in the silkworm haploid genome, contains only one exon, and its 5'-upstream sequence does not have a JH response element. Although Bommo-JHDK is highly expressed in the gut of the silkworm, its mRNA expression remains at a constant level during larval development suggesting this enzyme is constitutive and not regulated by JH, at least at the transcriptional level. Recombinant Bommo-JHDK catalyzed the conversion of 10S-JH diol into JH diol phosphate, confirming its enzymatic function. Recombinant enzyme formed a dimer and had biochemical characteristics similar to other JHDKs. Bommo-JHDK, a calcium-binding protein with kinase activity, provides unique insights on how JH levels are regulated in the silkworm. PMID:16203205

  19. Antioxidants Inhibit Formation of 3-Monochloropropane-1,2-diol Esters in Model Reactions.

    Science.gov (United States)

    Li, Chang; Jia, Hanbing; Shen, Mingyue; Wang, Yuting; Nie, Shaoping; Chen, Yi; Zhou, Yongqiang; Wang, Yuanxing; Xie, Mingyong

    2015-11-11

    The capacities of six antioxidants to inhibit the formation of 3-monochloropropane-1,2 diol (3-MCPD) esters were examined in this study. Inhibitory capacities of the antioxidants were investigated both in chemical models containing the precursors (tripalmitoyl glycerol, 1,2-dipalmitoyl-sn-glycerol, monopalmitoyl glycerol, and sodium chloride) of 3-MCPD esters and in oil models (rapeseed oil and sodium chloride). Six antioxidants, butylated hydroxytoluene (BHT), butylated hydroxy anisole (BHA), tert-butyl hydroquinone (TBHQ), propyl gallate (PG), L-ascorbyl palmitate (AP), and α-tocopherol (VE), were found to exhibit inhibiting capacities on 3-MCPD ester formation both in chemical models and in oil models. TBHQ provided the highest inhibitory capacity both in chemical models and in oil models; 44% of 3-MCPD ester formation was inhibited in the presence of TBHQ (66 mg/kg of oil) after heating of rapeseed oil at 230 °C for 30 min, followed by PG and AP. BHT, BHA, and VE appeared to have weaker inhibitory abilities in both models. VE exhibited the lowest inhibition rate; 22% of 3-MCPD esters were inhibited in the presence of VE (172 mg/kg of oil) after heating of rapeseed oil at 230 °C for 30 min. In addition, the inhibition rates of PG and VE decreased dramatically with an increase in temperature or heating time. The results suggested that some antioxidants, such as TBHQ, PG, and AP, could be the potential inhibitors of 3-MCPD esters in practice. PMID:26478126

  20. Binding site for the adenosyl group of coenzyme B12 in diol dehydrase

    International Nuclear Information System (INIS)

    The binding of cob(II)alamin (CblII) and 5'-deoxyadenosine to diol dehydrase was studied spectroscopically and with [U-14C]5'-deoxyadenosine. CblII was bound to this enzyme forming a tight 1:1 complex which was resistant to oxidation by O2 even in the presence of CN-. An irreversible 1:1:1 ternary complex was formed between enzyme, CblII, and 5'-deoxyadenosine, when the enzyme was incubated first with the nucleoside and then with CblII. When this order of addition of the constituents was reversed, no 5'-deoxyadenosine was bound to the enzyme-CblII complex. Hydroxocobalamin could also bind to the enzyme together with the nucleoside, while other cob(III)alamins bearing a bulkier Co beta ligand displaced the nucleoside upon binding to the enzyme. The binding of [U-14C]5'-deoxyadenosine was strongly inhibited by unlabeled 5'-deoxy-ara-adenosine, 4',5'-anhydroadenosine, adenosine, adenine, and 5',8-cyclic adenosine, in this order, but not by 5'-deoxyuridine. These results constitute direct evidence for the presence of the binding site for the adenosyl group of adenosylcobalamin, which is spatially limited to and highly specific for adenine nucleosides. The binding of 5'-deoxyadenosine to the apoenzyme was reversible

  1. Urinary 5α-androstane-3α,17β-diol radioimmunoassay: a new clinical evaluation

    International Nuclear Information System (INIS)

    A rapid specific and reliable RIA for urinary 5α-androstane-3α, 17β-diol (Adiol) is described using chromatographical purification and a specific antibody. Values are reported under some physiological and pathological conditions in 179 individuals. In 43 normal adult men the mean (+- SD) urinary Adiol excretion was 193 +- 77 μg/24 h, and in 29 normal women it was 44 +- 23 μg/24 h. These values are significantly different (P < 0.01). In 49 hirsute women, urinary Adiol Excretion was elevated (137 +- 51 μg/24 h) and significantly different from this value in normal women (P < 0.01). The urinary Adiol excretion in 10 postmenopausal women was very low (< 5 μg/24 h). In normal adult subjects, the theoretical contribution to urinary Adiol of the major secreted androgens was calculated. Whereas dehydroisoandrosterone and dehydroisoandrosterone sulfate yield the same amount of urinary Adiol in both sexes, testosterone is the main precursor of Adiol in men and androstenedione is the main precursor in normal premenopausal and hirsute women. However, the amount of Adiol recovered in the 24-h urine depends not only on the secretion rate of androstenedione and testosterone but is also related to the testosterone 5α-reductase activity present in androgen target cells, especially in sexual skin

  2. Mussel-inspired soft-tissue adhesive based on poly(diol citrate) with catechol functionality.

    Science.gov (United States)

    Ji, Yali; Ji, Ting; Liang, Kai; Zhu, Lei

    2016-02-01

    Marine mussels tightly adhering to various underwater surfaces inspires human to design adhesives for wet tissue adhesion in surgeries. Characterization of mussel adhesive plaques describes a matrix of proteins containing 3,4-dihydroxyphenylalanine (DOPA), which provides strong adhesion in aquatic conditions. Several synthetic polymer systems have been developed based on this DOPA chemistry. Herein, a citrate-based tissue adhesives (POEC-d) was prepared by a facile one-pot melt polycondensation of two diols including 1,8-octanediol and poly(ethylene oxide) (PEO), citric acid (CA) and dopamine, and the effects of hydrophilic and soft PEO on the properties of adhesives were studied. It was found that the obtained adhesives exhibited water-soluble when the mole ratio of PEO to 1,8-octanediol was 70%, and the equilibrium swelling percentage of cured adhesive was about 144%, and degradation rate was in the range of 1-2 weeks. The cured adhesives demonstrated soft rubber-like behavior. The lap shear adhesion strength measured by bonding wet pig skin was in the range of 21.7-33.7 kPa, which was higher than that of commercial fibrin glue (9-15 kPa). The cytotoxicity tests showed the POEC-d adhesives had a low cytotoxicity. Our results supports that POEC-d adhesives, which combined strong wet adhesion with good biodegradability, acceptable swelling ratio, good elasticity and low cytotoxicity, have potentials in surgeries where surgical tissue adhesives, sealants, and hemostatic agents are used. PMID:26704547

  3. Salphen-Co(III) complexes catalyzed copolymerization of epoxides with CO2

    Czech Academy of Sciences Publication Activity Database

    Hošťálek, Z.; Mundil, R.; Císařová, I.; Trhlíková, Olga; Grau, E.; Peruch, F.; Cramail, H.; Merna, J.

    2015-01-01

    Roč. 63, 20 April (2015), s. 52-61. ISSN 0032-3861 Institutional support: RVO:61389013 Keywords : cobalt salphen catalyst * CO2 epoxide copolymerization * MALDI-TOF Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

  4. Ultrathin CuO nanorods: controllable synthesis and superior catalytic properties in styrene epoxidation.

    Science.gov (United States)

    Jia, Wei; Liu, Yuxi; Hu, Pengfei; Yu, Rong; Wang, Yu; Ma, Lei; Wang, Dingsheng; Li, Yadong

    2015-05-25

    Ultrathin copper oxide (CuO) nanorods with diameters of ∼3.6 nm were obtained in one step using oleylamine (OAm) as both the solvent and the surface controller. The oriented attachment is responsible for the formation of the ultrathin CuO nanorods. Furthermore, this ultrathin nanostructure catalyst exhibited excellent activity and high styrene oxide yields in styrene epoxidation. PMID:25920405

  5. An investigation into the Ti-grafting structure on MCM-41 and epoxidation catalysis

    DEFF Research Database (Denmark)

    Yuan, Q.C.; Hagen, A.; Roessner, F.

    2006-01-01

    The structure of titanium species grafted on a purely siliceous MCM-41 and their catalysis in the epoxidation of cyclohexene with tert-butyl hydroperoxide (TBHP) were investigated. FT-IR, XANES and UV-vis were used for the examination of the Ti-grafted MCM-41. The results indicated that the titan...

  6. Epoxidation of Alkenes with Aqueous Hydrogen Peroxide and Quaternary Ammonium Bicarbonate Catalysts

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Kegnæs, Søren

    2013-01-01

    A range of solid and liquid catalysts containing bicarbonate anions were synthesised and tested for the epoxidation of alkenes with aqueous hydrogen peroxide. The combination of bicarbonate anions and quaternary ammonium cations opens up for new catalytic systems that can help to overcome challen...

  7. Manganese porphyrin immobilized on magnetite nanoparticles as a recoverable nanocatalyst for epoxidation of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Saeedi, Mohammad Saleh; Tangestaninejad, Shahram, E-mail: stanges@sci.ui.ac.ir; Moghadam, Majid, E-mail: moghadamm@sci.ui.ac.ir; Mirkhani, Valiollah; Mohammadpoor-Baltork, Iraj; Khosropour, Ahmad Reza

    2014-07-01

    Efficient epoxidation of alkenes catalysed by tetraphenylporphyrinatomanganese(III) chloride, [Mn(TPP)Cl], supported on silica coated magnetite nanoparticles, SiO{sub 2}–Fe{sub 3}O{sub 4}, is reported. First, the SiO{sub 2}–Fe{sub 3}O{sub 4} nanoparticles were modified with triethoxysilylpropyl chloride and then with imidazole. In the final step, [Mn(TPP)Cl] was attached to the support via axial ligation. The prepared catalyst was characterized by elemental analysis, FT-IR and diffuses reflectance UV–vis spectroscopic methods, and scanning electron microscopy. This new heterogenized catalyst was used for efficient epoxidation of alkenes with NaIO{sub 4} at room temperature. The catalyst is of high reusability in the epoxidation reactions, in which it was reused several times without significant loss of its catalytic activity. - Highlights: • The [Mn(TPP)Cl] was supported on silica coated magnetic nanoparticles. • The [Mn(TPP)Cl@Im–SiO{sub 2}–Fe{sub 3}O{sub 4}] heterogeneous catalyst was characterized. • The [Mn(TPP)Cl@Im–SiO{sub 2}–Fe{sub 3}O{sub 4}]/NaIO{sub 4} catalytic system was used for alkene epoxidation. • The catalyst was efficient and reusable.

  8. Genetically lowered microsomal epoxide hydrolase activity and tobacco-related cancer in 47,000 individuals

    DEFF Research Database (Denmark)

    Lee, Julie; Dahl, Morten; Nordestgaard, Børge G

    2011-01-01

    Two functional polymorphisms of the microsomal epoxide hydrolase (mEH) gene (EPHX1), Tyr113His (rs1051740) and His139Arg (rs2234922), have variably been found to influence susceptibility to various cancer forms. We tested whether genetically lowered mEH activity affects risk of developing cancer in...

  9. Synthesis of Cyclic Carbonates from CO2 and Epoxides Catalyzed by Hexaalkylguanidinium Halides

    Institute of Scientific and Technical Information of China (English)

    DUAN Hai-feng; LI Sheng-hai; LIN Ying-jie; XIE Hai-bo; ZHANG Suo-bo; WANG Zong-mu

    2004-01-01

    Hexaalkylguanidinium halides exhibit an efficient catalytic activity in the synthesis of cyclic carbonates from epoxides and carbon dioxide. By this method cyclic carbonates can be obtained in a high yield and a high selectivity at a low temperature and atmospheric pressure. This procedure is easy for the product isolation and recycling of the catalyst.

  10. UTL titanosilicate: An extra-large pore epoxidation catalyst with tunable textural properties

    Czech Academy of Sciences Publication Activity Database

    Přech, Jan; Čejka, Jiří

    -, - (2015). ISSN 0920-5861 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : titanosilicate UTL * top-down synthesis * epoxidation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  11. Thermal behavior of epoxidized cardanol diethyl phosphate as novel renewable plasticizer for poly(vinyl chloride)

    Science.gov (United States)

    A novel plasticizer, epoxidized cardanol diethyl phosphate (ECEP), based on cardanol was synthesized. Chemical structure of ECEP was characterized by fourier transform infrared (FTIR), 1H-nuclear magnetic resonance(1H NMR) and 13C-nuclear magnetic resonance(13C NMR) spectroscopy. Effects of ECEP sub...

  12. Crack resistance increasing in epoxide-rubber coatings of NPP room floors

    International Nuclear Information System (INIS)

    Problems of crack resistance increasing in epoxide-rubber coatings for the floors are considered. Exploitation experience of the floors in the special rooms of NPP is given. Perspectivity of application of the compositions described as the building materials for nuclear power stations is pointed out

  13. Synthesis of epoxidized cardanol and its antioxidative properties for vegetable oils and biodiesel

    Science.gov (United States)

    A novel antioxidant epoxidized cardanol (ECD), derived from cardanol, was synthesized and characterized by FT-IR, 1H-NMR and 13C-NMR. Oxidative stability of ECD used in vegetable oils and biodiesel was evaluated by pressurized differential scanning calorimetry (PDSC) and the Rancimat method, respect...

  14. Catalyzed ring-opening polymerization of epoxidized soybean oil by hydrated and anhydrous fluoroantimonic acids

    Science.gov (United States)

    Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by the super acid, fluroantimonic acid hexahydrate (HSbF6-6H2O), and the anhydrous form (HSbF6) in ethyl acetate was conducted in an effort to develop useful biodegradable polymers. The resulting polymerized ESO (SA-RPESO and SAA-...

  15. Dinuclear ru-aqua complexes for selective epoxidation catalysis based on supramolecular substrate orientation effects

    KAUST Repository

    Di Giovanni, Carlo

    2014-03-03

    Ru-aqua complex {[RuII(trpy)(H2O)] 2(μ-pyr-dc)}+ is a powerful epoxidation catalyst for a wide range of linear and cyclic alkenes. High turnover numbers (TNs), up to 17000, and turnover frequencies (TOF), up to 24120 h-1 (6.7 s -1), have been obtained using PhIO as oxidant. This species presents an outstanding stereospecificity for both cis and trans olefins towards the formation of their corresponding cis and trans epoxides. In addition, it shows different reactivity to cis and trans olefins due to a substrate orientation supramolecular effect transmitted by its ligand scaffold. This effect together with the impressive reaction rates are rationalized using electrochemical techniques and DFT calculations. A new Ru-aqua complex that behaves as a powerful epoxidation catalyst for a wide range of linear and cyclic alkenes is reported. High turnover numbers and frequencies are obtained by using PhIO as oxidant. The complex shows an outstanding stereospecificity for both cis and trans olefins towards the formation of their corresponding cis and trans epoxides (see figure). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Novel prokaryotic epoxide hydrolase and Baeyer-Villiger monooxygenase genes from metagenome

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Václav; Kotík, Michael; Marešová, Helena; Valešová, Renata; Grulich, Michal

    Bratislava : Československá spoločnosť mikrobiologická, 2010. s. 57-57. ISBN 970-80-970477-8-8 Institutional research plan: CEZ:AV0Z50200510 Keywords : epoxide hydrolases * environmental DNA Subject RIV: EE - Microbiology, Virology

  17. EPOXIDATION OF SMALL ORGANIC MOLECULES USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The commodity-scale epoxidation of several organic molecules has been carried out using a Spinning Tube-in-Tube (STTr) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Process Intensification, a...

  18. Synthesis of Chiral Cyclic Carbonates via Kinetic Resolution of Racemic Epoxides and Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Xiao Wu

    2016-01-01

    Full Text Available The catalytic synthesis of cyclic carbonates using carbon dioxide as a C1-building block is a highly active area of research. Here, we review the catalytic production of enantiomerically enriched cyclic carbonates via kinetic resolution of racemic epoxides catalysed by metal-containing catalyst systems.

  19. Coupling of Carbon Dioxide with Epoxides Catalyzed by Amino Acid Hydrochloride Salts

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Using amino acid hydrochloride salt as a catalyst, the coupling reaction of CO2 with epoxides could proceed smoothly to give cyclic carbonates in very good yields and high selectivity. The reaction conditions such as the pressure of carbon dioxide, reaction temperature, time and catalyst loading were carefully investigated.

  20. Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

    Science.gov (United States)

    Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2-ethylhexanol, benzyl alcohol, in the presence of Bronsted acid catalyst, were investigated. Products that were not reported in prior studies of similar reactions were found. These were furan fatty acid a...

  1. Synthesis of an Epoxide Carbonylation Catalyst: Exploration of Contemporary Chemistry for Advanced Undergraduates

    Science.gov (United States)

    Getzler, Yutan D. Y. L.; Schmidt, Joseph A. R.; Coates, Geoffrey W.

    2005-01-01

    A class of highly active, well-defined compounds for the catalytic carbonylation of epoxides and aziridines to beta-lactones and beta-lactams are introduced. The synthesis of one of the catalysts involves a simple imine condensation to form the ligand followed by air-sensitive metalation and salt metathesis steps.

  2. EPOXIDE RING OPENING AND RELATED REACTIVITIES OF CYCLOPENTAL POLYCYCLIC AROMATIC HYDROCARBONS: QUANTUM MECHANICAL STUDIES

    Science.gov (United States)

    For a series of cyclopenta-polynuclear aromatic hydrocarbons, epoxidated in the cyclopenta ring, semi-empirical AM1 calculations, and single point ab initio calculations using the 3-21g split valence basis set, have been performed for the each carbocation that might be formed by ...

  3. Functionalization of multi-walled carbon nanotubes by epoxide ring-opening polymerization

    International Nuclear Information System (INIS)

    In this study, covalent functionalization of carbon nanotubes (CNTs) was accomplished by surface-initiated epoxide ring-opening polymerization. FT-IR spectra showed that polyether and epoxide group covalently attached to the sidewalls of CNTs. TGA results indicated that the polyether was successfully grown from the CNT surface, with the final products having a polymer weight percentage of ca. 14–74 wt%. The O/C ratio of CNTs increased significantly from 5.1% to 29.8% after surface functionalization of CNTs. SEM and TEM images of functionalized CNTs exhibited that the tubes were enwrapped by polymer chains with thickness of several nanometers, forming core–shell structures with CNTs at the center. - Graphical abstract: Functionalized CNTs were enwrapped by polymer chains with thickness of several nanometers, forming core–shell structures with CNTs at the center. Highlights: ► CNTs were functionalized by epoxide ring-opening polymerization. ► Polyether and epoxide group covalently attached to the sidewalls of CNTs. ► Functionalized CNTs have a polymer weight percentage of ca. 14–74 wt%. ► Functionalized CNTs were enwrapped by polymer chains with thickness of several nanometers.

  4. EXPRESSION AND CHARACTERIZATION OF THE RECOMBINANT JUVENILE HORMONE EPOXIDE HYDROLASE (JHEH) FROM MANDUCA SEXTA. (R825433)

    Science.gov (United States)

    The cDNA of the microsomal Juvenile Hormone Epoxide Hydrolase (JHEH) from Manduca sexta was expressed in vitro in the baculovirus system. In insect cell culture, the recombinant enzyme (Ms-JHEH) was produced at a high level (100 fold over background EH catalytic activit...

  5. Mononuclear Nonheme High-Spin Iron(III)-Acylperoxo Complexes in Olefin Epoxidation and Alkane Hydroxylation Reactions.

    Science.gov (United States)

    Wang, Bin; Lee, Yong-Min; Clémancey, Martin; Seo, Mi Sook; Sarangi, Ritimukta; Latour, Jean-Marc; Nam, Wonwoo

    2016-02-24

    Mononuclear nonheme high-spin iron(III)-acylperoxo complexes bearing an N-methylated cyclam ligand were synthesized, spectroscopically characterized, and investigated in olefin epoxidation and alkane hydroxylation reactions. In the epoxidation of olefins, epoxides were yielded as the major products with high stereo-, chemo-, and enantioselectivities; cis- and trans-stilbenes were oxidized to cis- and trans-stilbene oxides, respectively. In the epoxidation of cyclohexene, cyclohexene oxide was formed as the major product with a kinetic isotope effect (KIE) value of 1.0, indicating that nonheme iron(III)-acylperoxo complexes prefer C═C epoxidation to allylic C-H bond activation. Olefin epoxidation by chiral iron(III)-acylperoxo complexes afforded epoxides with high enantioselectivity, suggesting that iron(III)-acylperoxo species, not high-valent iron-oxo species, are the epoxidizing agent. In alkane hydroxylation reactions, iron(III)-acylperoxo complexes hydroxylated C-H bonds as strong as those in cyclohexane at -40 °C, wherein (a) alcohols were yielded as the major products with high regio- and stereoselectivities, (b) activation of C-H bonds by the iron(III)-acylperoxo species was the rate-determining step with a large KIE value and good correlation between reaction rates and bond dissociation energies of alkanes, and (c) the oxygen atom in the alcohol product was from the iron(III)-acylperoxo species, not from molecular oxygen. In isotopically labeled water (H2(18)O) experiments, incorporation of (18)O from H2(18)O into oxygenated products was not observed in the epoxidation and hydroxylation reactions. On the basis of mechanistic studies, we conclude that mononuclear nonheme high-spin iron(III)-acylperoxo complexes are strong oxidants capable of oxygenating hydrocarbons prior to their conversion into iron-oxo species via O-O bond cleavage. PMID:26816269

  6. Inherent Stereospecificity in the Reaction of Aflatoxin B1 8,9-Epoxide with Deoxyguanosine and Efficiency of DNA Catalysis

    OpenAIRE

    Brown, Kyle L.; Bren, Urban; Stone, Michael P.; Guengerich, F. Peter

    2009-01-01

    Kinetic analysis of guanine alkylation by aflatoxin B1 exo-8,9-epoxide, the reactive form of the hepatocarcinogen aflatoxin B1, reveals the reaction to be > 2000-times more efficient in DNA than in aqueous solution, i.e. with free 2’-deoxyguanosine. Thermodynamic analysis reveals AFB1 exo-8,9-epoxide intercalation as the predominant source of the observed DNA catalytic effect. However, the known exo > endo epoxide stereospecificity of the DNA alkylation is observed even with free deoxyguanosi...

  7. Co(salen)-mediated enantioselective radiofluorination of epoxides. Synthesis and biological evaluation of both enantiomers of [18F]FMISO

    DEFF Research Database (Denmark)

    Revunov, Evgeny V.

    The purpose of this PhD project was to develop an enantioselective cobalt-mediated radiofluorination of epoxides and apply this methodology for radiosynthesis of the PET radiopharmaceutical [18F]FMISO. The developed procedure utilizes [18F]HF-gas (as an efficient source of nucleophilic 18F......(salen)-mediated no-carrier-added radiofluorination of epoxides has been achieved for the first time. A number of model meso-epoxides were successfully radiofluorinated producing 18F-fluorohidrines in high RCC and RCY, and modest enantioselectivity. The developed procedure is simple, rapid and lends itself to easy...

  8. In Silico Prediction of Cytochrome P450-Mediated Biotransformations of Xenobiotics: A Case Study of Epoxidation.

    Science.gov (United States)

    Zhang, Jing; Ji, Li; Liu, Weiping

    2015-08-17

    Predicting the biotransformation of xenobiotics is important in toxicology; however, as more compounds are synthesized than can be investigated experimentally, powerful computational methods are urgently needed to prescreen potentially useful candidates. Cytochrome P450 enzymes (P450s) are the major enzymes involved in xenobiotic metabolism, and many substances are bioactivated by P450s to form active compounds. An example is the conversion of olefinic substrates to epoxides, which are intermediates in the metabolic activation of many known or suspected carcinogens. We have calculated the activation energies for epoxidation by the active species of P450 enzymes (an iron-oxo porphyrin cation radical oxidant, compound I) for a diverse set of 36 olefinic substrates with state-of-the-art density functional theory (DFT) methods. Activation energies can be estimated by the computationally less demanding method of calculating the ionization potentials of the substrates, which provides a useful and simple predictive model based on the reaction mechanism; however, the preclassification of these diverse substrates into weakly polar and strongly polar groups is a prerequisite for the construction of specific predictive models with good predictability for P450 epoxidation. This approach has been supported by both internal and external validations. Furthermore, the relation between the activation energies for the regioselective epoxidation and hydroxylation reactions of P450s and experimental data has been investigated. The results show that the computational method used in this work, single-point energy calculations with the B3LYP functional including zero-point energy and solvation and dispersion corrections based on B3LYP-optimized geometries, performs well in reproducing the experimental trends of the epoxidation and hydroxylation reactions. PMID:26200167

  9. Discovery of a Novel Microsomal Epoxide Hydrolase-Catalyzed Hydration of a Spiro Oxetane.

    Science.gov (United States)

    Li, Xue-Qing; Hayes, Martin A; Grönberg, Gunnar; Berggren, Kristina; Castagnoli, Neal; Weidolf, Lars

    2016-08-01

    Oxetane moieties are increasingly being used by the pharmaceutical industry as building blocks in drug candidates because of their pronounced ability to improve physicochemical parameters and metabolic stability of drug candidates. The enzymes that catalyze the biotransformation of the oxetane moiety are, however, not well studied. The in vitro metabolism of a spiro oxetane-containing compound AZD1979 [(3-(4-(2-oxa-6-azaspiro[3.3]heptan-6-ylmethyl)phenoxy)azetidin-1-yl)(5-(4-ethoxyphenyl)-1,3,4-oxadiazol-2-yl)methanone] was studied and one of its metabolites, M1, attracted our interest because its formation was NAD(P)H independent. The focus of this work was to elucidate the structure of M1 and to understand the mechanism(s) of its formation. We established that M1 was formed via hydration and ring opening of the oxetanyl moiety of AZD1979. Incubations of AZD1979 using various human liver subcellular fractions revealed that the hydration reaction leading to M1 occurred mainly in the microsomal fraction. The underlying mechanism as a hydration, rather than an oxidation reaction, was supported by the incorporation of (18)O from H2 (18)O into M1. Enzyme kinetics were performed probing the formation of M1 in human liver microsomes. The formation of M1 was substantially inhibited by progabide, a microsomal epoxide hydrolase inhibitor, but not by trans-4-[4-(1-adamantylcarbamoylamino)cyclohexyloxy]benzoic acid, a soluble epoxide hydrolase inhibitor. On the basis of these results, we propose that microsomal epoxide hydrolase catalyzes the formation of M1. The substrate specificity of microsomal epoxide hydrolase should therefore be expanded to include not only epoxides but also the oxetanyl ring system present in AZD1979. PMID:27256986

  10. Investigation on the Protective Effects of Cranberry Against the DNA Damage Induced by Benzo[a]pyrene

    OpenAIRE

    Morales-González, José A.; Jaime Esquivel-Soto; César Esquivel-Chirino; Teresa Sumaya-Martínez; Tomas Fregoso-Aguilar; Jorge Mendoza-Pérez; José Gutiérrez-Salinas; Manuel Sánchez-Gutiérrez; Clara Zúñiga Pérez; Jeannett A. Izquierdo-Vega; Gloria Solano-Solano; Carmen Valadez-Vega; Sonia Fragoso-Antonio; Eduardo Madrigal-Santillán

    2012-01-01

    There are few reports that demonstrate the antigenotoxic potential of cranberries. Although the types of berry fruits consumed worldwide are many, this paper focuses on cranberries that are commonly consumed in Mexico (Vaccinium macrocarpon species). The purpose of the present study is to determine whether cranberry ethanolic extract (CEE) can prevent the DNA damage produced by benzo[a]pyrene (B[a]P) using an in vivo mouse peripheral blood micronucleus assay. The experimental groups were orga...

  11. Seasonal trends of benzo(a)pyrene in suspended particulate matter in urban areas of Belgrade, Serbia

    OpenAIRE

    Snežana Matić-Besarabić; Ljiljana Adjanski-Spasić; Milena Jovašević-Stojanović; Anka Cvetković; Dragan A. Marković

    2010-01-01

    Polycyclic aromatic hydrocarbons (PAHs) were identified to be one of the major toxic air pollutants in urban environment. PAHs are mostly formed during incomplete combustion or pyrolysis of organic material. According to Serbian National Legislation, benzo(a)pyrene (BaP) concentration in total suspended particles (TSP) in ambient air in the Belgrade metropolitan area has been determined in the last ten years, as a part of a local air pollution monitoring program performed by the Public Health...

  12. Intercalation of 1,n-diols into strontium phenylphosphonate: how the shape of the host layers influences arrangement of the guest molecules.

    Science.gov (United States)

    Melánová, Klára; Kovář, Petr; Beneš, Ludvík; Svoboda, Jan; Veteška, Marek; Pospíšil, Miroslav; Zima, Vítězslav

    2015-12-15

    Strontium phenylphosphonate intercalates with 1,n diols (n=2-4, 6-8) having general formula SrC6H5PO3⋅x(HO(CH2)nOH)⋅yH2O were prepared by precipitation from strontium phenylphosphonate solution and the corresponding diols. Prepared compounds exhibit a very good stability at ambient conditions. The intercalates were characterized by X-ray diffraction, thermogravimetry and elemental analysis. Thanks to the existence of free spaces among the benzene rings the diols exhibit a peculiar intercalation behavior. This behavior is explained on the basis of molecular simulation, which facilitated to elucidate the arrangement of the diol (guest) molecules in the specifically shaped space between the layers of the host material. From the structural point of view the intercalates can be divided into two subgroups: (i) intercalates with 1,2- to 1,4-diols and (ii) intercalates with 1,6- to 1,8-diols. The alkanediols of the first group are immersed in the free spaces among the benzene groups, their molecules adopt a horseshoe shape meaning cis conformation and are bonded by both of their OH groups to one host layer. The longer alkanediol chains of the second group allow anchoring to both neighboring layers of the host forming a kind of pillared structure in the interlayer space. The diol molecules are in this case bonded to the host layers by their OH groups to the oxygen atoms of the host layers and to water molecules present in the interlayer space through hydrogen bonds. The values of the basal spacing obtained from the experimental powder X-ray patterns are in a very good agreement with the basal spacing values calculated from the models. The molecular simulation of a 1,5-pentanediol intercalate, which we were not be able to synthesize, explained why this intercalate cannot be stable. PMID:26319335

  13. Abscisic (ABA)-aldehyde is a precursor to, and 1',4'-trans-ABA-diol a catabolite of, ABA in apple

    International Nuclear Information System (INIS)

    Previous 18O labeling studies of abscisic acid (ABA) have shown that apple (Malus domestica Borkh. cv Granny Smith) fruits synthesize a majority of [18O]ABA with the label incorporated in the 1'-hydroxyl position and unlabeled in the carboxyl group (JAD Zeevaart, TG Heath, DA Gage [1989] Plant Physiol 91: 1594-1601). It was proposed that exchange of 18O in the side chain with the medium occurred at an aldehyde intermediate stage of ABA biosynthesis. We have isolated ABA-aldehyde and 1'-4'-trans-ABA-diol (ABA-trans-diol) from 18O-labeled apple fruit tissue and measured the extent and position of 18O incorporation by tandem mass spectrometry. 18O-Labeling patterns of ABA-aldehyde, ABA-trans-diol, and ABA indicate that ABA-aldehyde is a precursor to, and ABA-trans-diol a catabolite of, ABA. Exchange of 18O in the carbonyl of ABA-aldehyde can be the cause of loss of 18O from the side chain of [18O]ABA. Results of feeding experiments with deuterated substrates provide further support for the precursor-product relationship of ABA-aldehyde → ABA → ABA-trans-diol. The ABA-aldehyde and ABA-trans-diol contents of fruits and leaves were low, approximately 1 and 0.02 nanograms per gram fresh weight for ABA-aldehyde and ABA-trans-diol, respectively, while ABA levels in fruits ranged from 10 to 200 nanograms per gram fresh weight. ABA biosynthesis was about 10-fold lower in fruits than in leaves. In fruits, the majority of ABA was conjugated to β-D-glucopyranosyl abscisate, whereas in leaves ABA was mainly hydroxylated to phaseic acid. Parallel pathways for ABA and trans-ABA biosynthesis and conjugation in fruits and leaves are proposed

  14. Determination of benzo[a]pyrene and dibenzopyrenes in a Chinese coal fly ash certified reference material.

    Science.gov (United States)

    Masala, Silvia; Bergvall, Christoffer; Westerholm, Roger

    2012-08-15

    Air pollution from coal combustion is of great concern in China because coal is the country's principal source of energy and it has been estimated that coal combustion is one of the main sources of polycyclic aromatic hydrocarbon (PAH) emissions in the nation. This study reports the concentrations of 15 PAHs including benzo[a]pyrene, dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene in a coal fly ash certified reference material (CRM) from China. To the best of our knowledge, dibenzo[a,l]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene concentrations in coal fly ash particles have not previously been reported. Benzo[a]pyrene is the only one of the studied hydrocarbons whose concentration in the coal fly ash CRM had previously been certified. The concentration of this species measured in this present work was twice the certified value. This is probably because of the exhaustive accelerated solvent extraction method employed. Consecutive extractions indicated an extraction recovery in excess of 95% for benzo[a]pyrene. For the other determined PAHs, repeat extractions indicated recoveries above 90%. PMID:22728296

  15. Irradiation crosslinking of poly(vinylchloride)/ epoxidized natural rubber blend

    International Nuclear Information System (INIS)

    Irradiation crosslinking of 50/50 poly(vinyl chloride)/ epoxidized natural rubber (PVC/ ENR) was studied with particular attention to blending parameters, addition of a crosslinking agent (TMPTA) and addition of an antioxidant (Irganox 1010). The 50/ 50 PVC/ ENR blend was prepared with a Brabender Plasticoder. The blend was irradiated by using a 3 MeV electron beam accelerator with doses ranging from 0-200 kGy. Changes in tensile properties, hardness, gel fraction, dynamic mechanical and morphological properties of the blends with irradiation doses were investigated. Evidences from DMA, FTIR, Foz Model, Charlesby-Pineer equation and crosslink density results were also employed to characterize the occurrence of irradiation-induced crosslinking. The possible mechanism of crosslinking induced by the irradiation between PVC and ENR was also proposed. It was observed that the mixing parameters such as temperature and time studied in this work are important in enhancement of irradiation induced crosslinking in PVC/ ENR blend. Results revealed that a readily compatible blend prepared at 150 degree Celsius, 50 rpm and 10 minutes of minimum mixing time enjoy maximum benefit from irradiation. However, irradiation was found to impart compatibility to the partially compatible PVC/ ENR blends prepared at 140 degree Celsius, 50 rpm and 10 minutes due to the irradiation-induced crosslinking. Electron beam initiated crosslinking of PVC/ ENR, containing trimethylolpropane triacrylate (TMPTA), has been carried out over a range of irradiation doses (20-200 kGy) and concentrations of TMPTA (1 to 5 phr). Blends containing 3-4 phr TMPTA were found to achieve optimum crosslinking, which in effect causes a maximum in tensile strength at 70 kGy. It was evident from FTIR spectra that the irradiation-induced reaction in PVC/ ENR blend involves the ring opening of the epoxy group to form ether bonds. Upon irradiation, the fractured surface topography changes from ductile to brittle as results

  16. Kinetic models of reaction systems for the in situ epoxidation of unsaturated fatty acid esters and triglycerides

    Directory of Open Access Journals (Sweden)

    Janković Milovan R.

    2004-01-01

    Full Text Available Mathematical models that describe the kinetics of reaction systems for the in situ epoxidation of unsaturated fatty acid esters or triglycérides with organic peracids are reviewed in this paper. The advantages and inadequacies of each model are discussed. A mono-phase pseudo-first order kinetic model was compared with a two phase model based on the Langmuir-Hinshelwood-Hougen-Watson (LHHW postulates proposed by the authors of this paper. The comparison was performed on the experimentally determined values for the in situ epoxidation of soybean oil by peracetic acid in the presence of different quantities of ion exchange resin used as the catalyst. It was concluded that a complete model for in situ epoxidation in the presence of ion exchange resin as the catalyst was still not given for perorganic acid formation. In particular, we report here the possibilities of the creation of an "ideal" model for in situ epoxidation.

  17. Octopus Manganese Porphyrin with Polyglycol Chains as a Catalyst for the β-Selective Epoxidation of Cholesterol Derivatives

    Institute of Scientific and Technical Information of China (English)

    Run Hua LI; Yuan Cong ZHAO; Jiang WU; Jing Song YOU; Xiao Qi YU

    2004-01-01

    Synthesis of a novel octopus porphyrin with polyglycol chains 1a was achieved.The catalytic activity of 1a's manganese complex for the epoxidation of cholesterol derivatives with PhIO give a satisfactory conversion and regioselectivity.

  18. Novel Routes to Angular and Linear Triquinanes via Radical Induced Epoxide Fragmentation-H-Abstraction-Cyclization Cascades

    OpenAIRE

    Krishnamurthy Venkat; Rawal Viresh H.

    1998-01-01

    Reported below are the first two applications of our radical induced epoxide fragmentation-H-abstraction-cyclization sequence to triquinane compounds. This tandem sequence has provided the basis of novel routes to both linear and angular triquinanes.

  19. Soluble Epoxide Hydrolase Deficiency or Inhibition Attenuates Diet-induced Endoplasmic Reticulum Stress in Liver and Adipose Tissue*

    OpenAIRE

    Bettaieb, Ahmed; Nagata, Naoto; AbouBechara, Daniel; Chahed, Samah; Morisseau, Christophe; Hammock, Bruce D; Haj, Fawaz G.

    2013-01-01

    Background: Soluble epoxide hydrolase (sEH) is a cytosolic enzyme whose pharmacological inhibition or targeted deletion in mice has beneficial effects, including improved insulin signaling in liver and adipose tissue.

  20. Epoxide pathways improve model predictions of isoprene markers and reveal key role of acidity in aerosol formation

    Science.gov (United States)

    Isoprene significantly contributes to organic aerosol in the southeastern United States where biogenic hydrocarbons mix with anthropogenic emissions. In this work, the Community Multiscale Air Quality model is updated to predict isoprene aerosol from epoxides produced under both ...

  1. Cyclo-Aliphatic Epoxide Based Photo Cured Gelled Electrolytes for Secondary Li Battery Applications. Electrochemical Kinetic Studies

    Science.gov (United States)

    Nagasubramanian, G.; Surampudi, S.; Halpert, G.

    1993-01-01

    Cyclo aliphatic epoxide based thin gelled fils prepared by UV photo curing were characterized electrochemically. Thylene carbonate (EC) mixed with different organic liquids in different volume ratios were used as solvents.

  2. 3-D QSAR ANALYSIS OF INHIBITION OF MURINE SOLUBLE EPOXIDE HYDROLASE (MSEH) BY BENZOYLUREAS, ARYLUREAS, AND THEIR ANALOGUES. (R825433)

    Science.gov (United States)

    Two hundred and seventy-one compounds including benzoylureas, arylureas and related compounds were assayed using recombinant murine soluble epoxide hydrolase (MsEH) produced from a baculovirus expression system. Among all the insect growth regulators assayed, 18 benzoylphenylu...

  3. Flow cytometric analysis of mitotic cycle perturbation by chemical carcinogens in cultured epithelial cells. [Effects of benzo(a)pyrene-diol-epoxide on mitotic cycle of cultural mouse liver epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Pearlman, A.L.

    1978-08-01

    A system for kinetic analysis of mitotic cycle perturbation by various agents was developed and applied to the study of the mitotic cycle effects and dependency of the chemical carcinogen benzo(a)pyrene-diolepoxide, DE, upon a mouse lever epithelial cell line, NMuLi. The study suggests that the targets of DE action are not confined to DNA alone but may include cytoplasmic structures as well. DE was found to affect cells located in virtually every phase of the mitotic cycle, with cells that were actively synthesizing DNA showing the strongest response. However, the resulting perturbations were not confined to S-phase alone. DE slowed traversal through S-phase by about 40% regardless of the cycle phase of the cells exposed to it, and slowed traversal through G/sub 2/M by about 50%. When added to G/sub 1/ cells, DE delayed recruitment of apparently quiescent (G/sub 0/) cells by 2 hours, and reduced the synchrony of the cohort of cells recruited into active proliferation. The kinetic analysis system consists of four elements: tissue culture methods for propagating and harvesting cell populations; an elutriation centrifugation system for bulk synchronization of cells in various phases of the mitotic cycle; a flow cytometer (FCM), coupled with appropriate staining protocols, to enable rapid analysis of the DNA distribution of any given cell population; and data reduction and analysis methods for extracting information from the DNA histograms produced by the FCM. The elements of the system are discussed. A mathematical analysis of DNA histograms obtained by FCM is presented. The analysis leads to the detailed implementation of a new modeling approach. The new modeling approach is applied to the estimation of cell cycle kinetic parameters from time series of DNA histograms, and methods for the reduction and interpretation of such series are suggested.

  4. Heat-Modeling of Microwave Assisted Epoxidation of Palm Acid Oil

    Directory of Open Access Journals (Sweden)

    N. Saifuddin

    2011-01-01

    Full Text Available Problem statement: While microwave chemistry could well be the most convenient, rapid and energy-saving way to initiate a chemical reaction, the issues of thermal versus microwave specific effect remain unaddressed. Approach: A three-dimensional Finite Element Model (FEM was developed to predict temperature profile during the enzymatic epoxidation of palm acid oil using microwave heating. Three-dimensional partial differential equations are formulated for the electromagnetic field and heat and mass transfer processes. The temperature profile of the FEM generated from the commercial software (ANSYS Emag was verified using experimental data from microwave oven heated samples containing palm acid oil and reactants in cylindrical bottles and has compared favorably with real time data. An Infra Red thermometer was used to measure temperature of the reactants during the real time experiment to ensure less contact with the reaction vessel. Results: Apart from ascertaining the temperature profile of the epoxidation process in the cylindrical bottle, the heat-modeling of this reaction can predict the Energy required during the reaction and provide insights to non-thermal microwave effects. It has shown the possibility of Microwave Non-Thermal Effects and Microwave Selectivity in Substrate Specificity. The energy used by the microwave irradiated reaction is by far much lesser than the energy used in conventional heating. This study has also improved the epoxidation process of Palm Acid Oil by incorporating enzyme as a catalyst and using microwave heating. Epoxidation can be done rapidly and at a lower level of activation energy of 27.767 kJ mol−1. It is a green process with increased efficiency as it reduced a typically 5-hour reaction to less than an hour. Conclusion: In this study, a quantitative view of a microwave assisted process of enzymatic epoxidation has been established. We have successfully developed and experimentally

  5. Influence of the incorporation process of clay as filler on the properties of natural rubber and epoxidized natural vulcanized rubber

    International Nuclear Information System (INIS)

    Vulcanizates of natural rubber and epoxidized natural rubber, having clay as filler were prepared by different process. The degree of exfoliation of the clay was evaluated by X-ray analysis and mechanical properties were determined by stress-strain. The crosslink density was evaluated by swelling measurements. It could be observed that the use of epoxidized rubber improves significantly the mechanical properties of the vulcanizates. (author)

  6. A New Biocatalyst for Production of Optically Pure Aryl Epoxides by Styrene Monooxygenase from Pseudomonas fluorescens ST

    Science.gov (United States)

    Di Gennaro, Patrizia; Colmegna, Andrea; Galli, Enrica; Sello, Guido; Pelizzoni, Francesca; Bestetti, Giuseppina

    1999-01-01

    We developed a biocatalyst by cloning the styrene monooxygenase genes (styA and styB) from Pseudomonas fluorescens ST responsible for the oxidation of styrene to its corresponding epoxide. Recombinant Escherichia coli was able to oxidize different aryl vinyl and aryl ethenyl compounds to their corresponding optically pure epoxides. The results of bioconversions indicate the broad substrate preference of styrene monooxygenase and its potential for the production of several fine chemicals. PMID:10347083

  7. Evaluation of the influence of the polymer-filler interaction on compounds based on epoxidized elastomeric matrix and precipitated silica

    OpenAIRE

    Tatiana L. A. C. Rocha; Marly M. Jacobi; Dimitrios Samios; Robert H. Schuster

    2006-01-01

    The introduction of epoxy groups into the main chain of elastomers has emerged as a promising alternative, considering the monitoring of polymer-filler interaction leading to changes in the properties of vulcanizates. The epoxidation reaction (in situ) was chosen to modify elastomers, such as polybutadiene (BR) and copolymer of styrene-butadiene-rubber (SBR), because it is a simple, easily controlled reaction, even considering the small epoxidation degree. The modification degree of the polym...

  8. Ruthenium complexes with N/C-donor ligands redox catalysts for water oxidation and the epoxidation of alkenes

    OpenAIRE

    Aguiló Carreras, Joan

    2013-01-01

    The understanding of the water oxidation reaction to molecular oxygen is still one of the great challenges faced by scientific community. On the other hand the epoxidation of olefins is a reaction of high relevance in both industry and academia. Epoxides are important intermediates in the chemical industry, particularly for the synthesis of various polymers and fine chemicals, such as pharmaceuticals, food additives, or flavor and fragrance compounds. Mononuclear and dinuclear Ru aqua complex...

  9. Synthesis of beta-lactones by the regioselective, cobalt and Lewis acid catalyzed carbonylation of simple and functionalized epoxides.

    Science.gov (United States)

    Lee, J T; Thomas, P J; Alper, H

    2001-08-10

    The PPNCo(CO)(4) and BF(3) x Et(2)O catalyzed carbonylation of simple and functionalized epoxides in DME gives the corresponding beta-lactones regioselectively in good to high yields. The carbonylation occurred selectively at the unsubstituted C-O bond of the epoxide ring, and this reaction tolerates various functional groups such as alkenyl, halide, hydroxy, and alkyl ether. PMID:11485465

  10. Biosynthesis of a linoleic acid allylic epoxide: mechanistic comparison with its chemical synthesis and leukotriene A biosynthesiss⃞

    OpenAIRE

    Niisuke, Katrin; Boeglin, William E.; Murray, John J; Schneider, Claus; Brash, Alan R.

    2009-01-01

    Biosynthesis of the leukotriene A (LTA) class of epoxide is a lipoxygenase-catalyzed transformation requiring a fatty acid hydroperoxide substrate containing at least three double bonds. Here, we report on biosynthesis of a dienoic analog of LTA epoxides via a different enzymatic mechanism. Beginning with homolytic cleavage of the hydroperoxide moiety, a catalase/peroxidase-related hemoprotein from Anabaena PCC 7120, which occurs in a fusion protein with a linoleic acid 9R-lipoxygenase, dehyd...

  11. Benzo[a]pyrene and Benzo[k]fluoranthene in some processed fish and fish products.

    Science.gov (United States)

    Olatunji, Olatunde S; Fatoki, Olalekan S; Opeolu, Beatrice O; Ximba, Bhekumusa J

    2015-01-01

    In this study, the concentration levels of the probable carcinogenic PAH fractions, benzo[a]pyrene (BaP) and benzo[k]fluoranthrene (BkF) in fillets of some processed fish species were investigated. Fish species comprising Merluccius poli (hake), Tyrsites atun (snoek), Seriola lalandi (yellow-tail) and Brama brama (angel fish) were bought in fish shops at Gordon's Bay, Western Cape, South Africa. The fish were gutted, filleted and prepared for edibility by frying, grilling and boiling. Polycyclic aromatic hydrocarbons were extracted from each homogenized fish sample, cleaned-up using solid phase extraction (SPE), and analysed for the PAH fractions, BaP and BkF using a Gas Chromatograph coupled with a Flame Ionization Detector (GC-FID). The sum of the two PAHs (∑2PAH) i.e., BaP and BkF ranged between 0.56 and 1.46 µg/kg, in all boiled, grilled and fried fish species. The fried fish extracts showed significantly higher (p < 0.05) abundance of ∑2PAH, than grilled and boiled fish. Dietary safety and PAHs toxicity was also discussed. PMID:25607603

  12. Benzo[a]pyrene and Benzo[k]fluoranthene in Some Processed Fish and Fish Products

    Directory of Open Access Journals (Sweden)

    Olatunde S. Olatunji

    2015-01-01

    Full Text Available In this study, the concentration levels of the probable carcinogenic PAH fractions, benzo[a]pyrene (BaP and benzo[k]fluoranthrene (BkF in fillets of some processed fish species were investigated. Fish species comprising Merluccius poli (hake, Tyrsites atun (snoek, Seriola lalandi (yellow-tail and Brama brama (angel fish were bought in fish shops at Gordon’s Bay, Western Cape, South Africa. The fish were gutted, filleted and prepared for edibility by frying, grilling and boiling. Polycyclic aromatic hydrocarbons were extracted from each homogenized fish sample, cleaned-up using solid phase extraction (SPE, and analysed for the PAH fractions, BaP and BkF using a Gas Chromatograph coupled with a Flame Ionization Detector (GC-FID. The sum of the two PAHs (∑2PAH i.e., BaP and BkF ranged between 0.56 and 1.46 µg/kg, in all boiled, grilled and fried fish species. The fried fish extracts showed significantly higher (p < 0.05 abundance of ∑2PAH, than grilled and boiled fish. Dietary safety and PAHs toxicity was also discussed.

  13. Effects of benzo(a)pyrene exposure on the antioxidant enzyme activity of scallop Chlamys farreri

    Institute of Scientific and Technical Information of China (English)

    PAN Luqing; REN Jiayun; ZHENG Debin

    2009-01-01

    Scallop Chlamys farreri was exposed to different concentrations of benzo(a)pyrene (BaP) (0.5 μg/L, 1.0 μg/L, 10.0 μg/L and 50.0 μg/L) for 30 days in seawater. The 7-ethoxyresorufin O-deethylase (EROD) activity was significantly induced, and increased with the increasing BaP concentration. The glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), Glutathione peroxidase (GPx) activities increased in short time at low concentration of BaP, and was significantly depressed at high concentrations. Scallop gill was more sensitive to BaP than the digestive gland, and the digestive gland was the main tissue to deal with oxyradicals. The contents of malondialdehyde (MDA) increased with the exposure time and there was a positive correlation (concentration-effect) between the MDA content and the concentration of BaP. The biomarkers determined in this experiment had important roles in detoxification, and showed great potential as biomarkers for oxidative stress. Controlled laboratory experiments designed to simulate field exposure scenarios are particularly useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.

  14. Skin tumor-initiating activities of the twelve isomeric phenols of benzo(a)pyrene

    International Nuclear Information System (INIS)

    The skin tumor-initiating activities of the 12 isomeric phenols of benzo(a)pyrene (BP) were determined in mice by use of a two-stage system of tumorigenesis. 11-Hydroxybenzo(a)pyrene was moderately active, whereas 2-hydroxybenzo(a)pyrene and BP were strong tumor initiators when applied topically to CD-1 mice and followed by twice-weekly applications of the promoter 12-O-tetradecanoylphorbol-13-acetate. 1-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, and 12-hydroxybenzo(a)pyrene had less than 5% of the tumor-initiating activity of BP when the data were expressed as papillomas per mouse. After 30 weeks of promotion, the number of papillomas per mouse was 8.4, 8.5, and 2.8, respectively, for the animals treated with BP, 2-hydroxybenzo(a)pyrene, and 11-hydroxybenzo(a)pyrene. A 5-week latency period before the appearance of the first tumor was observed after the application of either 2-hydroxybenzo(a)pyrene or BP, whereas a slightly longer latency period of 7 weeks was observed following application of 11-hydroxybenzo(a)pyrene. The time required for 50% of the animals to develop tumors was 13 weeks for animals treated with BP and 15 weeks for animals treated with 2- or 11-hydroxybenzo(a)pyrene

  15. Seasonal trends of benzo(apyrene in suspended particulate matter in urban areas of Belgrade, Serbia

    Directory of Open Access Journals (Sweden)

    Snežana Matić-Besarabić

    2010-09-01

    Full Text Available Polycyclic aromatic hydrocarbons (PAHs were identified to be one of the major toxic air pollutants in urban environment. PAHs are mostly formed during incomplete combustion or pyrolysis of organic material. According to Serbian National Legislation, benzo(apyrene (BaP concentration in total suspended particles (TSP in ambient air in the Belgrade metropolitan area has been determined in the last ten years, as a part of a local air pollution monitoring program performed by the Public Health Institute of Belgrade and funded by Belgrade’s Municipality. Air samples for analysis of BaP in suspended particleshave been collected (as 24 h sample once per month at selected onitoring sites within the municipal air quality monitoring network. At the beginning, according to National Regulation, all samples were taken as total suspended particles (TSP. Since mid-2008, the procedure of sampling methodology was harmonized with EU requirements and solid fraction PM10 has been collected and analyzed using GC/MS. In this study, we have analyzed results of TSP collected between 2005 and 2008. Looking through the results obtained during the period of a whole year, it can be noticed that concentrations of BaP were much higher during winter season at almost all measuring sites.

  16. Can biomonitors effectively detect airborne benzo[a]pyrene? An evaluation approach using modelling

    Science.gov (United States)

    Ratola, Nuno; Jiménez-Guerrero, Pedro

    2016-04-01

    Biomonitoring data available on levels of atmospheric polycyclic aromatic hydrocarbons (PAHs) in pine needles from the Iberian Peninsula were used to estimate air concentrations of benzo[a]pyrene (BaP) and, at the same time, fuelled the comparison with chemistry transport model representations. Simulations with the modelling system WRF+EMEP+CHIMERE were validated against data from the European Monitoring and Evaluation Programme (EMEP) air sampling network. Modelled atmospheric concentrations were used as a consistent reference in order to compare the performance of vegetation-to-air estimating methods. A spatial and temporal resolution of 9 km and 1 h was implemented. The field-based database relied on a pine needles sampling scheme comprising 33 sites in Portugal and 37 sites in Spain complemented with the BaP measurements available from the EMEP sites. The ability of pine needles to act as biomonitoring markers for the atmospheric concentrations of BaP was estimated by converting the levels obtained in pine needles into air concentrations by six different approaches, one of them presenting realistic concentrations when compared to the modelled atmospheric values. The justification for this study is that the gaps still exist in the knowledge of the life cycles of semi-volatile organic compounds (SVOCs), particularly the partition processes between air and vegetation. The strategy followed in this work allows for the effective estimation by the model of concentrations in air and vegetation and of the best approaches to estimate atmospheric levels from values found in vegetation.

  17. Synthesis of modified potato starches for aqueous solubilization of benzo[a]pyrene.

    Science.gov (United States)

    Delsarte, Isabelle; Danjou, Pierre-Edouard; Veignie, Etienne; Rafin, Catherine

    2016-06-25

    For soil rehabilitation, the surfactant-enhanced remediation has emerged as a promising technology. For this purpose, starch derivatives were difunctionalized by 1,4-butane sultone (BS) and 2-octen-1-ylsuccinic anhydride (OSA). Eight distinct products were obtained under different synthesis conditions. The chemical structural characteristics were investigated by (1)H NMR spectroscopy. The compounds were evaluated for their apparent aqueous solubility and their ability to increase the solubility of a hydrophobic pollutant such as benzo[a]pyrene (BaP), used as a polycyclic aromatic hydrocarbon model. In comparison with native starch, the best obtained compound increased starch apparent aqueous solubility by a factor of 10 (up to 3.50g/L) and also stimulated 77-fold BaP aqueous solubilization (up to 232.97μg/L) underlining its very high surfactant property. In this study, the right balance between hydrophobic character (octenyl succinate group (OS) grafted) of starch derivatives and starch apparent aqueous solubility (BS grafted) was highlighted. PMID:27083796

  18. In Vivo Anti-Tumor Activity and Toxicological Evaluations of Perillaldehyde 8,9-Epoxide, a Derivative of Perillyl Alcohol

    Science.gov (United States)

    Andrade, Luciana Nalone; Amaral, Ricardo Guimarães; Dória, Grace Anne Azevedo; Fonseca, Cecília Santos; da Silva, Tayane Kayane Mariano; Albuquerque Júnior, Ricardo Luiz Cavalcante; Thomazzi, Sara Maria; do Nascimento, Lázaro Gomes; Carvalho, Adriana Andrade; de Sousa, Damião Pergentino

    2016-01-01

    Recent studies have revealed the high cytotoxicity of p-menthane derivatives against human tumor cells. In this study, the substance perillaldehyde 8,9-epoxide, a p-menthane class derivative obtained from (S)-(−)-perillyl alcohol, was selected in order to assess antitumor activity against experimental sarcoma 180 tumors. Toxicological effects related to the liver, spleen, kidneys and hematology were evaluated in mice submitted to treatment. The tumor growth inhibition rate was 38.4%, 58.7%, 35.3%, 45.4% and 68.1% at doses of 100 and 200 mg/kg/day for perillaldehyde 8,9-epoxide, perillyl alcohol and 25 mg/kg/day for 5-FU intraperitoneal treatments, respectively. No toxicologically significant effect was found in liver and kidney parameters analyzed in Sarcoma 180-inoculated mice treated with perillaldehyde 8,9-epoxide. Histopathological analyses of the liver, spleen, and kidneys were free from any morphological changes in the organs of the animals treated with perillaldehyde 8,9-epoxide. In conclusion, the data suggest that perillaldehyde 8,9-epoxide possesses significant antitumor activity without systemic toxicity for the tested parameters. By comparison, there was no statistical difference for the antitumor activity between perillaldehyde 8,9-epoxide and perillyl alcohol. PMID:26742032

  19. Defect Stabilized Gold Atoms on Graphene as Potential Catalysts for Ethylene Epoxidation: A First-principles Investigation

    KAUST Repository

    Liu, Xin

    2015-11-24

    We performed a first-principles based investigation on the potential role of Au atoms stabilized by defects on graphene in ethylene epoxidation. We showed that the interactions between the Au atoms and vacancies on graphene not only make the Au atomic diffusion a 2.10 eV endothermic process, but also tune the energy level of Au-d states for the activation of O2 and ethylene and promote the formation and dissociation of the peroxametallacycle intermediate. The catalytic cycle of ethylene epoxidation is initiated with the formation of a peroxametallacycle intermediate by the coadsorbed ethylene and O2, through the dissociation of which an ethylene epoxide molecule and an adsorbed O atom are formed. Then, gaseous ethylene reacts with the remnant O atom directly for the formation of another ethylene epoxide molecule. The desorption of ethylene epoxide is facilitated by the subsequent adsorption of O2 or ethylene and a new reaction cycle initiates. The calculated energy barriers for the formation and dissociation of the peroxametallacycle intermediate and the regeneration of Au sites are 0.30, 0.84 and 0.18 eV, respectively, and are significantly lower than those for aldehyde formation. These findings suggest the potential high catalytic performance of these Au atoms for ethylene epoxidation.

  20. In Vivo Anti-Tumor Activity and Toxicological Evaluations of Perillaldehyde 8,9-Epoxide, a Derivative of Perillyl Alcohol

    Directory of Open Access Journals (Sweden)

    Luciana Nalone Andrade

    2016-01-01

    Full Text Available Recent studies have revealed the high cytotoxicity of p-menthane derivatives against human tumor cells. In this study, the substance perillaldehyde 8,9-epoxide, a p-menthane class derivative obtained from (S-(−-perillyl alcohol, was selected in order to assess antitumor activity against experimental sarcoma 180 tumors. Toxicological effects related to the liver, spleen, kidneys and hematology were evaluated in mice submitted to treatment. The tumor growth inhibition rate was 38.4%, 58.7%, 35.3%, 45.4% and 68.1% at doses of 100 and 200 mg/kg/day for perillaldehyde 8,9-epoxide, perillyl alcohol and 25 mg/kg/day for 5-FU intraperitoneal treatments, respectively. No toxicologically significant effect was found in liver and kidney parameters analyzed in Sarcoma 180-inoculated mice treated with perillaldehyde 8,9-epoxide. Histopathological analyses of the liver, spleen, and kidneys were free from any morphological changes in the organs of the animals treated with perillaldehyde 8,9-epoxide. In conclusion, the data suggest that perillaldehyde 8,9-epoxide possesses significant antitumor activity without systemic toxicity for the tested parameters. By comparison, there was no statistical difference for the antitumor activity between perillaldehyde 8,9-epoxide and perillyl alcohol.

  1. Repellent activities of stereoisomers of p-menthane-3,8-diols against Anopheles gambiae (Diptera: Culicidae).

    Science.gov (United States)

    Barasa, Stephen S; Ndiege, Isaiah O; Lwande, Wilber; Hassanali, Ahmed

    2002-09-01

    Four stereoisomers of p-menthane-3,8-diol, which make up the natural product obtained from Eucalyptus citriodora, were synthesized through stereoselective procedures. Repellency assays showed that all the four were equally active against Anopheles gambiae s.s. Racemic blends and the diastereoisomeric mixture of all the four isomers were also equally repellent. 1-alpha-terpeneol, with a single hydroxyl function at C-8 and unsaturation at C-8, and menthol, with a single hydroxyl function at C-3, were not repellent. The practical implication of these results is discussed. PMID:12349856

  2. (Enantio)selective Hydrogen Autotransfer: Ruthenium-Catalyzed Synthesis of Oxazolidin-2-ones from Urea and Diols.

    Science.gov (United States)

    Peña-López, Miguel; Neumann, Helfried; Beller, Matthias

    2016-06-27

    A novel strategy for the synthesis of oxazolidin-2-ones from vicinal diols and urea is described. In this heterocycle synthesis, two different C-O and C-N bonds are sequentially formed in a domino process consisting of nucleophilic substitution and alcohol amination. The use of readily available starting materials and the good atom economy render this process environmentally benign. While this transformation is already highly chemo- and regioselective, we also developed the first asymmetric version of this method using (R)-(+)-MeO-BIPHEP as the chiral ligand. PMID:27072612

  3. Improved straightforward chemical synthesis of dihydroxyacetone phosphate through enzymatic desymmetrization of 2,2-dimethoxypropane-1,3-diol.

    Science.gov (United States)

    Charmantray, Franck; El Blidi, Lahssen; Gefflaut, Thierry; Hecquet, Laurence; Bolte, Jean; Lemaire, Marielle

    2004-12-24

    Dihydroxyacetone phosphate (DHAP) was synthesized in high purity and yield in four steps starting from dihydroxyacetone dimer (DHA) (47% overall yield). DHA was converted into 2,2-dimethoxypropane-1,3-diol, which was desymmetrized by acetylation with lipase AK. The alcohol function was phosphorylated to give dibenzyl phosphate ester 4. From 4, two routes were investigated for large-scale synthesis of DHAP. First, acetate hydrolysis was performed prior to hydrogenolysis of the phosphate protective groups. The acetal hydrolysis was finally catalyzed by the phosphate group itself. Second, acetate and acetal hydrolysis were performed in one single step after hydrogenolysis. PMID:15609974

  4. New thermally stable polyesters based on 2,5-pyridinedicarbonyl dichloride and aromatic diols: Synthesis and characterization

    Institute of Scientific and Technical Information of China (English)

    Hossein Nasr Isfahani; Khalil Faghihi

    2009-01-01

    Six new thermally stable polyesters (4a-f) were synthesized through the solution polycondensation reaction of 2,5-pyridine dicarbonyldichloride (2) with six aromatic diols in N,N'-dimethyl acetamide (DMAc) solution and in the presence of pyridine as a base. The polycondensation reactions produce a series of new polyesters (4a-f) in high yields, and inherent viscosity between 0.30 and 0.55 dL/g. The resulting polyesters were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test, Fourier transform infrared (FT-IR) spectroscopy and gel permeation chromatography (GPC).

  5. Photoinduced electron transfer and fluorescence mechanisms in covalently linked polynuclear aromatic-nucleotide complexes

    Science.gov (United States)

    Geacintov, Nicholas E.; Mao, Bing; France, Luisa L.; Zhao, Rushen; Chen, Junxin; Liu, Tong M.; Ya, Nai-Qi; Margulis, Leonid A.; Sutherland, John C.

    1992-04-01

    The fluorescence of polycyclic aromatic hydrocarbon-nucleic acid complexes is quenched by photoinduced electron transfer mechanisms in aqueous solutions at ambient temperatures. These effects are illustrated with the biologically important compound benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), a mutagenic and carcinogenic metabolite of the environmental pollutant benzo[a]pyrene, which forms covalent mutagenic lesions with 2'-deoxyguanosine (dG) residues in DNA. The dependence of the fluorescence yield and fluorescence decay times of the covalent model adduct (+)-trans- BPDE-N2-dG as a function of temperature and methanol/water composition are described. Because of the sensitivity of the fluorescence of the pyrenyl residue to the polarity of the microenvironment, the magnitude of the fluorescence yield can be used to distinguish between highly hydrophobic (e.g., intercalation) and other more solvent-exposed BPDE- nucleic acid binding sites.

  6. Synthesis, characterization and photo-epoxidation performance of Au-loaded photocatalysts

    Indian Academy of Sciences (India)

    Van-Huy Nguyen; Hsiang-Yu Chan; Jeffrey C S Wu

    2013-07-01

    Titanium silicalite-1 (TS-1) was synthesized by hydrothermal crystallization. Au-loaded TS-1 (Au/TS-1) was prepared by the photo-deposition method. The prepared photocatalysts have been fully characterized by Raman, Brunauer-Emmett-Teller (BET), transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet visible light spectroscopy to reveal their structure, surface morphology and chemical composition. Photocatalytic activity of these photocatalysts was ascertained by gas phase photo-epoxidation of propylene-to-propylene oxide in the presence of molecular oxygen only under light irradiation. No sacrificial reductant such as hydrogen was used during the photoreaction. Au/TS-1 photocatalyst remained highly stable under reaction conditions. It is found that the increased Ti3+ sites due to the incorporation of Au will not only enhance the selectivity of the photocatalyst to form epoxide but also its stability during C3H6 conversion.

  7. Controlling Catalytic Selectivity via Adsorbate Orientation on the Surface: From Furfural Deoxygenation to Reactions of Epoxides.

    Science.gov (United States)

    Pang, Simon H; Medlin, J Will

    2015-04-16

    Specificity to desired reaction products is the key challenge in designing solid catalysts for reactions involving addition or removal of oxygen to/from organic reactants. This challenge is especially acute for reactions involving multifunctional compounds such as biomass-derived aromatic molecules (e.g., furfural) and functional epoxides (e.g., 1-epoxy-3-butene). Recent surface-level studies have shown that there is a relationship between adsorbate surface orientation and reaction selectivity in the hydrogenation pathways of aromatic oxygenates and the ring-opening or ring-closing pathways of epoxides. Control of the orientation of reaction intermediates on catalytic surfaces by modifying the surface or near-surface environment has been shown to be a promising method of affecting catalytic selectivity for reactions of multifunctional molecules. In this Perspective, we review recent model studies aimed at understanding the surface chemistry for these reactions and studies that utilize this insight to rationally design supported catalysts. PMID:26263134

  8. Kinetics of epoxidation of hexene-1 with isopropylbenzene hydroperoxide catalyzed by heteropolycompounds

    International Nuclear Information System (INIS)

    A study was made on homogeneous epoxidation of hexene-1 with isopropyltenzene hydroperoxide (IPBHP) in isopropanol solution at 110 deg, with heteropolycompounds (HPC) as catalysts. The reaction proceeds with the selectivity with respect to hexene oxide, close to 100%. Kinetic equation is found W=k' [HPC]sup(P)x[IPBHP][Csub(6)Hsub(12)], where p=0.5-0.9 for the case of Na3PMO12O40 at [HPC]=(0.2 to 9)x10-5 mol/l. Catalytic HPC activity decreases in the Na3PMo12O4approximately AlPMo12O40 > Na4PMo11VO40 > Na4SiMo12O40 >> Na3PW12O40 series. The reaction mechanism including a partial HPC destruction with the formation of Mo glycol complexes as real epoxidation catalysts is supposed

  9. Synthesis, characterization and catalytic activities towards epoxidation of olefins of dinuclear copper(II) complexes

    Science.gov (United States)

    Halder, Shibashis; Mukherjee, Aparajita; Ghosh, Koushik; Dey, Sudipto; Nandi, Mahasweta; Roy, Partha

    2015-12-01

    Two copper(II) complexes, [Cu2(L1)Cl3].2H2O (1) and [Cu2(L2)(N3)Cl2] (2) where HL1 = 4-methyl-2,6-bis((2-morpholinoethylimino)methyl)phenol and HL2 = 4-methyl-2,6-bis((3-morpholinopropylimino)methyl)phenol have been synthesized and characterized by elemental analysis, various spectroscopic methods, TGA and single crystal X-ray diffraction analysis. Single crystal X-ray diffraction analysis reveals that in both the complexes, two copper atoms are linked by phenoxo oxygen atom and a bridging ligand, namely chloride and azide, respectively. These complexes have been used as catalyst for the epoxidation of cyclohexene, styrene, α-methyl styrene, trans-stilbene and norbornene using tert-butyl hydroperoxide as the oxidant in acetonitrile under mild conditions. All of the substrates undergo conversion to produce respective epoxide as the major product.

  10. Hepatic and pulmonary cytosolic metabolism of epoxides effects of aging on conjugation with glutathione

    International Nuclear Information System (INIS)

    In liver cytosol from male Fischer 344 rats, glutathione S-transferase specific activities with six epoxide substrates were lower in the 24-month-old (senescent) group than in the 3-month-old (young) group. With lung cytosol from males and liver and lung cytosol from females, specific activities decline with only some of the substrates. Age-related increases in protein content in male and female rat liver occurred by 12 months of age (middle-age) and remained elevated through senescence. In addition, increases in liver weights in males similarly occured so that total metabolic rates tended to be highest in middle-aged males and similar in young and senescent groups. Few changes similar to these were found in liver cytosol from females or lung cytosol from males or females. Thus, tissue-, sex-, and substrate-specific alterations in epoxide metabolism occurred during aging

  11. Charpy impact test of cloth reinforced epoxide resin at low temperatures

    International Nuclear Information System (INIS)

    This chapter attempts to establish a method for obtaining dynamic toughness and to provide basic data for design, using the Charpy impact test at cryogenic temperatures and an epoxide and FRP with epoxide matrix as samples. Examines the failure mechanism and the potential problems associated with the use of these materials in practical applications in superconducting magnets. Concludes that impact strength at room temperature (RT) has larger values than those at liquid nitrogen temperature irrespective of impact velocity; impact strength can be improved by reinforcement using glass or carbon cloths; impact strength of reinforced plastics shows a dependence on off-axis angle and the dependence varies with the type of reinforcement, matrix and specimens shape; and impact strength of glass reinforced plastic (GRP) is larger than that of GRP when the specimen shape is identical

  12. Block Copolymerization of Lactide and an Epoxide Facilitated by a Redox Switchable Iron-Based Catalyst.

    Science.gov (United States)

    Biernesser, Ashley B; Delle Chiaie, Kayla R; Curley, Julia B; Byers, Jeffery A

    2016-04-18

    A cationic iron(III) complex was active for the polymerization of various epoxides, whereas the analogous neutral iron(II) complex was inactive. Cyclohexene oxide polymerization could be "switched off" upon in situ reduction of the iron(III) catalyst and "switched on" upon in situ oxidation, which is orthogonal to what was observed previously for lactide polymerization. Conducting copolymerization reactions in the presence of both monomers resulted in block copolymers whose identity can be controlled by the oxidation state of the catalyst: selective lactide polymerization was observed in the iron(II) oxidation state and selective epoxide polymerization was observed in the iron(III) oxidation state. Evidence for the formation of block copolymers was obtained from solubility differences, GPC, and DOSY-NMR studies. PMID:26991820

  13. Conglomerate formative precursor of chiral drug timolol: 3-(4-Morpholino-1,2,5-thiadiazol-3-yloxy)-propane-1,2-diol

    Science.gov (United States)

    Bredikhin, Alexander A.; Zakharychev, Dmitry V.; Fayzullin, Robert R.; Bredikhina, Zemfira A.; Gubaidullin, Aidar T.

    2015-05-01

    Solid state properties of 3-(4-N-morpholino-1,2,5-thiadiazol-3-yloxy)-propane-1,2-diol 3, the synthetic precursor of popular drug timolol, have been investigated. The original solubility test, the data of X-ray diffraction and DSC methods indicate that the compound is prone to spontaneous resolution. Diol 3 crystallizing from both enantiopure or racemic feed material forms "guaifenesin-like" crystal packing in which the classic H-bonded bilayers, framed in both sides by hydrophobic molecular fragments, act as the basic supramolecular motif. The main chain conformation of the molecules in the crystals of diol 3 differs from that in the guaifenesin crystals, and this fact changes the absolute configuration of spiral columns formed by intermolecular hydrogen bonds in crystals of 3 as compared with guaifenesin crystals.

  14. Studying PW-Amberlite catalyst deactivation in limonene epoxidation by hydrogen peroxide

    OpenAIRE

    Rolando Barrera Zapata; Aída Luz Villa Holguín de P.; Consuelo Montes de Correa

    2010-01-01

    The PW-Amberlite catalyst is active for limonene epoxidation in triphasic conditions; it becomes deactivated in reaction condi- tions. Catalyst stability during the reaction and recovery of catalyst activity when it was treated with several solvents were evalua- ted. It was found that the catalyst recovered 99% of its initial activity when it was washed with toluene and that the recovery was 95% and 97% when ethanol or acetone were used as washing solvents, respectively. Leaching tests ...

  15. Mechanism of Inhibition of Aliphatic Epoxide Carboxylation by the Coenzyme M Analog 2-Bromoethanesulfonate*

    OpenAIRE

    Boyd, Jeffrey M.; Clark, Daniel D.; Kofoed, Melissa A.; Ensign, Scott A.

    2010-01-01

    The bacterial metabolism of epoxypropane formed from propylene oxidation uses the atypical cofactor coenzyme M (CoM, 2-mercaptoethanesulfonate) as the nucleophile for epoxide ring opening and as a carrier of intermediates that undergo dehydrogenation, reductive cleavage, and carboxylation to form acetoacetate in a three-step metabolic pathway. 2-Ketopropyl-CoM carboxylase/oxidoreductase (2-KPCC), the terminal enzyme of this pathway, is the only known member of the disulfide oxidoreductase fam...

  16. The stability of the three transmembrane and the four transmembrane human vitamin K epoxide reductase models

    Science.gov (United States)

    Wu, Sangwook

    2016-04-01

    The three transmembrane and the four transmembrane helix models are suggested for human vitamin K epoxide reductase (VKOR). In this study, we investigate the stability of the human three transmembrane/four transmembrane VKOR models by employing a coarse-grained normal mode analysis and molecular dynamics simulation. Based on the analysis of the mobility of each transmembrane domain, we suggest that the three transmembrane human VKOR model is more stable than the four transmembrane human VKOR model.

  17. Biodegradable Shape Memory Polymeric Material from Epoxidized Soybean Oil and Polycaprolactone

    OpenAIRE

    Takashi Tsujimoto; Takeshi Takayama; Hiroshi Uyama

    2015-01-01

    This article deals with the synthesis of plant oil-based shape memory materials from epoxidized soybean oil (ESO) and polycaprolactone (PCL). PolyESO/PCLs were synthesized by an acid-catalyzed curing in the presence of PCL. During the reaction, PCL scarcely reacted with ESO and the crystallinity of the PCL component decreased to form a semi-interpenetrating network structure. The incorporation of the PCL components improved the maximum stress and strain at break of ESO-based network polymer. ...

  18. GENETIC VARIATION IN SOLUBLE EPOXIDE HYDROLASE (EPHX2) IS ASSOCIATED WITH FOREARM VASODILATOR RESPONSES IN HUMANS

    OpenAIRE

    Lee, Craig R.; Pretorius, Mias; Schuck, Robert N.; Burch, Lauranell H.; Bartlett, Jackie; Williams, Scott M.; ZELDIN, DARRYL C.; Brown, Nancy J.

    2010-01-01

    Cytochrome P450-derived epoxyeicosatrienoic acids are potent vasodilators in preclinical models and are hydrolyzed by soluble epoxide hydrolase (EPHX2). Associations between the EPHX2 Lys55Arg and Arg287Gln polymorphisms and cardiovascular disease risk have been reported; however, their impact on vascular function in humans has not been investigated. In 265 volunteers (198 white, 67 black American), forearm blood flow was measured by strain-gauge venous occlusion plethysmography at baseline a...

  19. Heat-Modeling of Microwave Assisted Epoxidation of Palm Acid Oil

    OpenAIRE

    N. Saifuddin; L. W. Zhan; K. X. Ning

    2011-01-01

    Problem statement: While microwave chemistry could well be the most convenient, rapid and energy-saving way to initiate a chemical reaction, the issues of thermal versus microwave specific effect remain unaddressed. Approach: A three-dimensional Finite Element Model (FEM) was developed to predict temperature profile during the enzymatic epoxidation of palm acid oil using microwave heating. Three-dimensional partial differential equations are formulated for the electromagne...

  20. IN VITRO SOLUBLE EPOXIDE HYDROLASE ENZYME INHIBITORY ACTIVITY OF SOME NOVEL CHALCONE DERIVATIVES

    OpenAIRE

    Kuppusamy Asokkumar; Lokeswari Prathyusha Tangella; Muthusamy Umamaheshwari; Thirumalaisamy Shivashanmugam; Varadharajan Subhadradevi; Puliyath Jagannath; Arumugam Madeswaran

    2012-01-01

    Objective Soluble epoxide hydrolase (sEH) belongs to the α/β -hydrolase superfamily, a subclass of α/β proteins. Chalcones are chemical compounds that show hopeful obliging efficacy in controlling numerous diseases. The main objective of the study is to evaluate the sEH inhibitory activity of some synthesized chalcone derivatives and identification of its mode of inhibition. Methods Four different chalcone derivatives (PC-1 to PC-4) were selected for synthesis by Claisen-Schmidt method. The i...

  1. Benzylpyrazinium Salts as Photo-Initiators in the Polymerization of Epoxide Monomers

    OpenAIRE

    Moon Suk Kim; Sang Bong Lee

    2014-01-01

    In order to study the capability of pyrazinium salt derivatives to act as photo-initiators of epoxide monomers, benzyl pyrazinium hexafluoroantimonate (BPH), benzyl 3,5-dimethyl pyrazine hexafluoroantimonate (BDH) and benzyl quinoxalinium hexafluoroantimonate (BQH) were synthesized by the Menschutkin reaction of benzyl bromide with pyrazine, 2,6-dimethyl pyrazine, and quinoxaline, followed by exchanging with hexafluoroantimonate (SbF6). BPH, BDH, and BQH exhibited characteristic ultraviolet ...

  2. The use of lipases as biocatalysts for the epoxidation of fatty acids and phenolic compounds

    OpenAIRE

    Durand, Erwann,; Lecomte, Jérôme,; Figueroa-Espinoza, Maria-Cruz,; Dubreucq, Eric; Fulcrand, Helene; Villeneuve, Pierre

    2014-01-01

    Lipases are versatile enzymes that can be used for various kinds of biocatalyzed reactions. Owing to their selectivity and their mild reaction conditions, they can be often considered as more interesting than classical chemical catalysts. Besides their application in oil and fat processes, these enzymes have proved to be very attractive for other lipase-catalyzed reactions. This review discusses the latest results where lipases are used for the epoxidation of lipid substrates (namely fatty ac...

  3. Imidazolinium salts as catalysts for the ring-opening alkylation of meso epoxides by alkylaluminum complexes.

    Science.gov (United States)

    Zhou, H; Campbell, E J; Nguyen, S T

    2001-07-12

    [reaction: see text] Imidazolinium salts and their N-heterocyclic carbene (NHC) derivatives catalyze the alkylation of a variety of meso epoxides in the presence of triethylaluminum (yield = 70-90%), under mild conditions. Imidazolinium salts are better catalysts than their NHC derivatives but can lead to dimerization side reactions under extended reaction time. Preformed NHC.AlEt(3) complexes and Wanzlick-type olefins, which are dimers of free NHCs, are also catalysts for this reaction. PMID:11440586

  4. Stabilizing effect of epoxidized sunflower oil as a secondary stabilizer for Ca/Hg stabilized PVC

    Directory of Open Access Journals (Sweden)

    2008-01-01

    Full Text Available Unsaturated triglyceride oil sunflower was epoxidized and characterized by chemical and spectroscopic methods. Epoxidized sunflower oil (ESO was used as an organic thermal co-stabilizer for rigid poly(vinyl chloride (PVC in the presence of tricalcium dicitrate (Ca3(C6H5O72 and mercury (II acetate (Hg(CH3COO2. The thermo-oxidative degradation of PVC was studied in the presence of these ternary stabilizer systems at 170, 180, 190 and 200°C in N2 atmosphere. The effects of metal carboxylate combination Ca/Hg in the absence and in the presence of epoxidized sunflower oil on static heat treatment of PVC have been studied. The formation of polyene sequences was investigated by UV-visible and FT-IR spectroscopy and by comparing viscosity data obtained in the presence and in the absence of the additives. It was found that the additives retard the rate of degradation and reduce the extent of polymer chain scission associated with the thermal degradation of poly(vinyl chloride. Synergistic effects were found when stabilizer was blended in 50:50 weight ratios with either. It was found that ESO exerted a stabilizing effect on the degradation of PVC. The activation energy for degraded PVC in absence of stabilizers was 38.6 kJ•mol–1 and in the presence of Ca/Hg and Ca/Hg/ESO were 53.3 and 64.7 kJ•mol–1 respectively. In order of compare the efficiency of the epoxidized sunflower oil with these metal soap stabilizers, thermal stabilities were evaluated on the basis of evolved hydrogen chloride determined by conductometry technique and degree of discoloration are discussed.

  5. Directed Evolution of an Enantioselective Epoxide Hydrolase : Uncovering the Source of Enantioselectivity at Each Evolutionary Stage

    OpenAIRE

    Reetz, Manfred T.; Bocola, Marco; Wang, Li-Wen; Sanchis, Joaquin; Cronin, Annette; Arand, Michael; Zou, Jinyu; Archelas, Alain; Bottalla, Anne-Lise; Naworyta, Agata; Mowbray, Sherry L.

    2009-01-01

    Directed evolution of enzymes as enantioselective catalysts in organic chemistry is an alternative to traditional asymmetric catalysis using chiral transition-metal complexes or organocatalysts, the different approaches often being complementary. Moreover, directed evolution studies allow us to learn more about how enzymes perform mechanistically. The present study concerns a previously evolved highly enantioselective mutant of the epoxide hydrolase from Aspergillus niger in the hydrolytic ki...

  6. Soluble Epoxide Hydrolase Inhibition: Targeting Multiple Mechanisms of Ischemic Brain Injury with a Single Agent

    OpenAIRE

    Iliff, Jeffrey J.; Alkayed, Nabil J.

    2009-01-01

    Soluble epoxide hydrolase (sEH) is a key enzyme in the metabolic conversion and degradation of P450 eicosanoids called epoxyeicosatrienoic acids (EETs). Genetic variations in the sEH gene, designated EPHX2, are associated with ischemic stroke risk. In experimental studies, sEH inhibition and gene deletion reduce infarct size after focal cerebral ischemia in mice. Although the precise mechanism of protection afforded by sEH inhibition remains under investigation, EETs exhibit a wide array of p...

  7. Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

    Science.gov (United States)

    Birdsall, A. W.; Miner, C. R.; Mael, L. E.; Elrod, M. J.

    2014-12-01

    Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters, and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied with experimental methods. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of similar magnitudes, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

  8. Synthesis of Marine Polycyclic Polyethers via Endo-Selective Epoxide-Opening Cascades

    OpenAIRE

    Jamison, Timothy F.; Ivan Vilotijevic

    2010-01-01

    The proposed biosynthetic pathways to ladder polyethers of polyketide origin and oxasqualenoids of terpenoid origin share a dramatic epoxide-opening cascade as a key step. Polycyclic structures generated in these biosynthetic pathways display biological effects ranging from potentially therapeutic properties to extreme lethality. Much of the structural complexity of ladder polyether and oxasqualenoid natural products can be traced to these hypothesized cascades. In this review we summarize ho...

  9. A stable epoxide as a potential endogenous estrogen metabolite: Possible significance in breast cancer?

    Science.gov (United States)

    Raeside, James I

    2016-06-01

    Epoxides as reactive intermediates of estrogen metabolism have been considered to be potential precursors of the 2- and 4-hydroxy, catechol estrogens and even to be mutagenic/carcinogenic agents themselves. The labile nature of the intermediates has made proof of their existence difficult in natural biological conditions. In our studies on estrogen metabolism in vitro, in various tissues from several laboratory and domestic species, there was chromatographic evidence of formation of a stable estrogen metabolite that could be seen after incubation with radiolabeled estrone, but not with unlabeled substrate. Investigation with acid treatment of the metabolite yielded material detected as 6-hydroxy-estrone-suggesting the presence of an additional oxygen atom in the molecule. An identification of the "unknown compound" has not yet been made but, with this evidence, the properties revealed so far can best be met by assuming the presence of 5,6-epoxy-estrone. The recent favorable reports on the role of 5α,6α-epoxy-cholesterol in breast cancer has led to the hypothesis that the formation of a similar, stable epoxide of an estrogen could potentially be a compound of interest. If a metabolic pathway from estrone to 6-hydroxy-estrone through a stable epoxide has indeed been observed, it would suggest that identifying and screening for the enzymes responsible for its production, as opposed to those generating the catecholestrogens, could provide valuable information in relation to breast cancer. The balance in production of estrogen epoxides could be a key factor in determining normal health or risk of tumor development. PMID:27142140

  10. Enantioselective Cross-Coupling of meso-Epoxides with Aryl Halides

    OpenAIRE

    Zhao, Yang; Weix, Daniel J.

    2015-01-01

    The first enantioselective cross-electrophile coupling of aryl bromides with meso-epoxides to form trans-β-arylcycloalkanols is presented. The reaction is catalyzed by a combination of (bpy)NiCl2 and a chiral titanocene under reducing conditions. Yields range from 57 to 99% with 78–95% enantiomeric excess. The 30 examples include a variety of functional groups (ether, ester, ketone, nitrile, ketal, trifluoromethyl, sulfonamide, sulfonate ester), both aryl and vinyl halides, and five- to seven...

  11. Reaction-based epoxide fluorescent probe for in vivo visualization of hydrogen sulfide.

    Science.gov (United States)

    Sathyadevi, Palanisamy; Chen, Yu-Jen; Wu, Shou-Cheng; Chen, Yen-Hao; Wang, Yun-Ming

    2015-06-15

    Hydrogen sulfide (H2S) has emerged as the most important biosynthetic gasotransmitters along with nitric oxide (NO) and carbon monoxide (CO). In this study, we report the design and the synthesis of a new epoxide fluorescent probe 7-glycidyloxy-9-(2-glycidyloxycarbonylphenyl)-2-xanthone (FEPO) for use in in vivo visualization of hydrogen sulfide. The probe employs a fluorescein as a fluorophore, and is equipped with an operating epoxide unit. FEPO functions via epoxide ring opening upon nucleophilic attack of H2S. This ring opening strategy may open a new avenue for the development of various H2S fluorescent sensors. FEPO showed high selectivity and high sensitivity for H2S. FEPO's cytotoxicity was tested using MTT (2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide) assay. Furthermore, the use of confocal imaging of H2S and in vivo imaging in live zebra fish demonstrated FEPO's potential biological applications. We anticipate that, owing to their ideal properties, probes of this type will find great uses in exploring the role of H2S in biology. PMID:25660659

  12. Epoxidation of methyl esters derived from Jatropha oil: An optimization study

    Energy Technology Data Exchange (ETDEWEB)

    Mushtaq, M.; Tan, I. M.; Nadeem, M.; Devi, C.; Lee, S. Y. C.; Sagir, M.; Radhid, U.

    2013-05-01

    The optimization of the epoxidation reaction of methyl esters obtained from Jatropha oil was appraised. Response surface methodology (RSM) based on a central composite rotatable design (CCRD) was employed for the experimental design. Four reaction variables namely hydrogen peroxide/ C=C mole ratio, formic acid/C=C mole ratio, reaction temperature and reaction time were evaluated. The optimum epoxidation conditions calculated by the quadratic model were 3.12 moles of hydrogen peroxide/C=C moles, 0.96 moles of formic acid/C=C moles, a reaction temperature of 70.0 degree centigrade and a reaction time of 277 minutes. A reaction optimized by the proposed process parameters provided a yield of 92.89 {+-} 1.29 wt.% with relatively improved reaction time. Hydrogen peroxide concentration and reaction temperature were found to be the most significant variables while reaction temperature and hydrogen peroxide showed strong interactions. The epoxidized methyl esters were analyzed using FT-IR, 1H NMR and {sup 1}3C NMR techniques. This study suggested relatively higher molar ratio of formic acid required than was proposed in the literature. (Author) 33 refs.

  13. Properties of composite laminates based on basalt fibers with epoxidized vegetable oils

    International Nuclear Information System (INIS)

    Highlights: • New environmentally friendly composites from biobased epoxies and basalt fibers. • Improved performance with conventional silane treatment on basalt fabrics. • Composites with excellent appearance due to basalt shiny brown color. • Potential applications as substitute of glass fiber reinforced composites in engineering design. • Processing with conventional resin transfer molding (RTM) techniques. - Abstract: This paper deals with the development of polymeric materials derived from epoxidized vegetable oils which have been used in the manufacture of laminated composite materials with basalt fabrics. Epoxidized linseed oil (ELO) and epoxidized soybean oil (ESBO) were used as biobased matrices. The basalt fabrics were modified with amino-silane and glycidyl-silane to increase fiber–matrix interactions. The curing behavior of both resins was evaluated by differential scanning calorimetry (DSC) and oscillatory rheometry (OR). The evaluation of mechanical properties was made by tensile, flexural and Charpy tests. The extent of the fiber–matrix interactions among interface was evaluated by scanning electron microscopy (SEM). The obtained results revealed that surface modification of basalt fibers with glycidyl-silane clearly improves the mechanical properties of the composites. The use of the ELO resin as matrix for composite laminates improved substantially the mechanical performance compared to composites made with ESBO

  14. Secondary deuterium isotope effects on olefin epoxidation by cytochrome P-450

    International Nuclear Information System (INIS)

    Secondary deuterium isotope effects have been determined for the epoxidation of p-phenylstyrene (1a) and p-methylstyrene (1b) by cytochrome P-450 of rat liver microsomes. With both substrates there was an inverse isotope effect of 7 per cent/deuterium (i.e. ksub(H)/ksub(D)=0.93) at Cα of the olefin, but no isotope effect was observed at Cβ. The epoxidation of (1a) by m-chloroperbenzoic acid has previously been shown to be accompanied by an inverse secondary isotope effect of 9 per cent/deuterium at Cβ, with no detectable isotope effect at C α. Thus in both the enzymatic (P-450) and non-enzymatic (peracid) epoxidation of styrene derivatives, the oxygen atom is transferred to the vinyl group in an asymmetric non-concerted fashion. However, the fact that the isotope effects for these two systems are reversed, together with previous comparisons of substituent effects on the two reactions, suggests that there is little mechanistic similarity between cytochrome P-450 enzymes and organic peracids as chemical models for these enzymes. (author)

  15. Optimization of the In Situ Epoxidation of Linoleic Acid of Jatropha Curcas Oil With Performic Acid

    International Nuclear Information System (INIS)

    The aim of this study is to optimise the epoxidation of linoleic acid of Jatropha curcas oil. This experiment was carried out with performic acid generated in situ by using hydrogen peroxide and formic acid. The method was evaluated on different parameters such as reaction temperature, mole ratios of formic acid to ethylenic unsaturation and hydrogen peroxide to ethylenic unsaturation. The optimum relative conversion into oxirane (80.4 %) and conversion of iodine (94.7 %) was achieved with ∼70 % yield at the condition of 45 degree Celsius reaction temperature, formic acid to ethylenic unsaturation mole ratio of 2.0, hydrogen peroxide to ethylenic unsaturation mole ratio of 12.0 for 2 hours of reaction time. The epoxidized linoleic acid was characterized by using Fourier transform infrared (FTIR) spectroscopy and NMR analysis. The result was also found that the formations of an epoxide and oxirane ring cleavage were both occurred at the same time if low amount of hydrogen peroxide was used. (author)

  16. High biobased content epoxy-anhydride thermosets from epoxidized sucrose esters of Fatty acids.

    Science.gov (United States)

    Pan, Xiao; Sengupta, Partha; Webster, Dean C

    2011-06-13

    Novel highly functional biobased epoxy compounds, epoxidized sucrose esters of fatty acids (ESEFAs), were cross-linked with a liquid cycloaliphatic anhydride to prepare polyester thermosets. The degree of cure or conversion was studied using differential scanning calorimetry (DSC), and the sol content of the thermosets was determined using solvent extraction. The mechanical properties were studied using tensile testing to determine Young's modulus, tensile stress, and elongation at break. Dynamic mechanical analysis (DMA) was used to determine glass-transition temperature, storage modulus, and cross-link density. The nanomechanical properties of the surfaces were studied using nanoindentation to determine reduced modulus and indentation hardness. The properties of coatings on steel substrates were studied to determine coating hardness, adhesion, solvent resistance, and mechanical durability. Compared with the control, epoxidized soybean oil, the anhydride-cured ESEFAs have high modulus and are hard and ductile, high-performance thermoset materials while maintaining a high biobased content (71-77% in theory). The exceptional performance of the ESEFAs is attributed to the unique structure of these macromolecules: well-defined compact structures with high epoxide functionality. These biobased thermosets have potential uses in applications such as composites, adhesives, and coatings. PMID:21561167

  17. Effect of the synthetic method on the catalytic activity of alumina: Epoxidation of cyclohexene

    International Nuclear Information System (INIS)

    Graphical abstract: Temperature influence on percent conversion and selectivity in the epoxidation of cyclohexene using commercial alumina as a catalyst. - Highlights: • Aluminum oxide was synthesized using Pechini method. • The alumina obtained showed a mix of boehmite and γ-alumina phases. • We research an economically feasible method to obtain alumina for use as a catalyst. • Alumina obtained by Pechini showed high percent conversion and/or selectivity. • The best results were 78% conversion and 78% selectivity to epoxidation reactions. - Abstract: Al2O3 was prepared from different inorganic precursors via the Pechini method and compared with Al2O3 prepared by the sol–gel method. Structural characterization of these materials was carried out by FTIR, X-ray diffraction (XRD), N2 adsorption at −196 °C and transmission electron microscopy (TEM). The solids were tested in the epoxidation of cyclohexene and a difference in their catalytic activities was observed. The characterization results indicate that the samples prepared by Pechini have a mixture of γ-alumina and boehmite, a condition favoring catalytic activity, whereas the sol–gel sample is less crystalline due to higher boehmite content. These results indicate that both the nature of the precursor and the method of synthesis strongly affect the catalytic activity of Al2O3

  18. Epoxidized Vegetable Oils Plasticized Poly(lactic acid Biocomposites: Mechanical, Thermal and Morphology Properties

    Directory of Open Access Journals (Sweden)

    Buong Woei Chieng

    2014-10-01

    Full Text Available Plasticized poly(lactic acid PLA with epoxidized vegetable oils (EVO were prepared using a melt blending method to improve the ductility of PLA. The plasticization of the PLA with EVO lowers the Tg as well as cold-crystallization temperature. The tensile properties demonstrated that the addition of EVO to PLA led to an increase of elongation at break, but a decrease of tensile modulus. Plasticized PLA showed improvement in the elongation at break by 2058% and 4060% with the addition of 5 wt % epoxidized palm oil (EPO and mixture of epoxidized palm oil and soybean oil (EPSO, respectively. An increase in the tensile strength was also observed in the plasticized PLA with 1 wt % EPO and EPSO. The use of EVO increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA. The SEM micrograph of the plasticized PLA showed good compatible morphologies without voids resulting from good interfacial adhesion between PLA and EVO. Based on the results of this study, EVO may be used as an environmentally friendly plasticizer that can improve the overall properties of PLA.

  19. Complex Cure Kinetics of the Hydroxyl-Epoxide Reaction in DGEBA Epoxy Hardened with Diethanolamine

    Science.gov (United States)

    Ancipink, Windy; McCoy, John; Kropka, Jamie; Celina, Mathias

    The curing of a diglycidyl ether of bisphenol-A Epoxy (Epon 828) with diethanolamine (DEA) involves a fast amine-epoxide reaction followed by a slower hydroxyl-epoxide reaction. At curing temperatures below 100°C, the time scales of these two reactions are well separated, and the hydroxyl addition can be studied as an ''isolated'' reaction. The hydroxyl-epoxide reaction is of great interest due to the complex kinetics involved, which are brought about by competing reactions. The reaction kinetics are believed to be tertiary amine catalyzed and are well fit to a modified form of the Kamal-type equation. Here we study the complex long term reaction kinetics at various temperatures, by using isothermal modulated differential scanning calorimetry, micro calorimetry, and infrared spectroscopy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  20. Persistence and changes in bioavailability of dieldrin, DDE and heptachlor epoxide in earthworms over 45 years

    Science.gov (United States)

    Beyer, W. Nelson; Gale, Robert W.

    2013-01-01

    The finding of dieldrin (88 ng/g), DDE (52 ng/g), and heptachlor epoxide (19 ng/g) in earthworms from experimental plots after a single moderate application (9 kg/ha) 45 years earlier attests to the remarkable persistence of these compounds in soil and their continued uptake by soil organisms. Half-lives (with 95 % confidence intervals) in earthworms, estimated from exponential decay equations, were as follows: dieldrin 4.9 (4.3-5.7) years, DDE 5.3 (4.7-6.1) years, and heptachlor epoxide 4.3 (3.8-4.9) years. These half-lives were not significantly different from those estimated after 20 years. Concentration factors (dry weight earthworm tissue/dry weight soil) were initially high and decreased mainly during the first 11 years after application. By the end of the study, average concentration factors were 1.5 (dieldrin), 4.0 (DDE), and 1.8 (heptachlor epoxide), respectively.

  1. Human microsomal epoxide hydrolase: genetic polymorphism and functional expression in vitro of amino acid variants

    Science.gov (United States)

    Hassett, Christopher; Aicher, Lauri; Sidhu, Jaspreet S.

    2016-01-01

    Human microsomal epoxide hydrolase (mEH) is a biotransformation enzyme that metabolizes reactive epoxide intermediates to more water-soluble trans-dihydrodiol derivatives. We compared protein-coding sequences from six full-length human mEH DNA clones and assessed potential amino acid variation at seven positions. The prevalence of these variants was assessed in at least 37 unrelated individuals using polymerase chain reaction experiments. Only Tyr/His 113 (exon 3) and His/Arg 139 (exon 4) variants were observed. The genotype frequencies determined for residue 113 alleles indicate that this locus may not be in Hardy – Weinberg equilibrium, whereas frequencies observed for residue 139 alleles were similar to expected values. Nucleotide sequences coding for the variant amino acids were constructed in an mEH cDNA using site-directed mutagenesis, and each was expressed in vitro by transient transfection of COS-1 cells. Epoxide hydrolase mRNA level, catalytic activity, and immunoreactive protein were evaluated for each construct. The results of these analyses demonstrated relatively uniform levels of mEH RNA expression between the constructs. mEH enzymatic activity and immunoreactive protein were strongly correlated, indicating that mEH specific activity was similar for each variant. However, marked differences were noted in the relative amounts of immunoreactive protein and enzymatic activity resulting from the amino acid substitutions. These data suggest that common human mEH amino acid polymorphisms may alter enzymatic function, possibly by modifying protein stability. PMID:7516776

  2. The mixed-ligand ternary complexes of neodymium(III) with L-histidine and L-cysteine with various diols

    International Nuclear Information System (INIS)

    The stability constants of the ternary complexes of the type MAB, MA2B, MAB2 where M = Neodymium(III), A = amino acids and B = diols, have been investigated by pH-metric technique (μ = 0.2, KNO3 at 30 +- 1degC) with both amino acids used as primary ligand. Stability constant data indicates that MA2B species were more stable than MAB and MAB2. The diols are responsible for the change in stability. The stability constants were correlated with basicities of different ligands present in the complexes. (author)

  3. Stability and in vivo behavior of Rh[16aneS4-diol]211At complex: A potential precursor for astatine radiopharmaceuticals

    International Nuclear Information System (INIS)

    Introduction: The heavy halogen 211At is of great interest for targeted radiotherapy because it decays by the emission of short-range, high-energy α-particles. However, many astatine compounds that have been synthesized are unstable in vivo, providing motivation for seeking other 211At labeling strategies. One relatively unexplored approach is to utilize prosthetic groups based on astatinated rhodium (III) complex stabilized with a tetrathioether macrocyclic ligand – Rh[16aneS4-diol]211At. The purpose of the current study was to evaluate the in vitro and in vivo stability of this complex in comparison to its iodine analog – Rh[16aneS4-diol]131I. Methods: Rh[16aneS4-diol]211At and Rh[16aneS4-diol]131I complexes were synthesized and purified by HPLC. The stability of both complexes was evaluated in vitro by incubation in phosphate-buffered saline (PBS) and human serum at different temperatures. The in vivo behavior of the two radiohalogenated complexes was assessed by a paired-label biodistribution study in normal Balb/c mice. Results: Both complexes were synthesized in high yield and purity. Almost no degradation was observed for Rh[16aneS4-diol]131I in PBS over a 72 h incubation. The astatinated analog exhibited good stability in PBS over 14 h. A slow decline in the percentage of intact complex was observed for both tracers in human serum. In the biodistribution study, retention of 211At in most tissues was higher than that of 131I at all time points, especially in spleen and lungs. Renal clearance of Rh[16aneS4-diol]211At and Rh[16aneS4-diol]131I predominated, with 84.1 ± 2.3% and 94.6 ± 0.9% of injected dose excreted via the urine at 4 h. Conclusions: The Rh[16aneS4-diol]211At complex might be useful for constructing prosthetic groups for the astatination of biomolecules and further studies are planned to evaluate this possibility

  4. Organocatalyzed direct aldol condensation using L-proline and BINAM-prolinamides: regio-, diastereo-, and enantioselective controlled synthesis of 1,2-diols

    OpenAIRE

    Guillena Townley, Gabriela; Hita López, María del Carmen; Nájera Domingo, Carmen

    2006-01-01

    Recoverable BINAM-prolinamide derivatives, as well as L-proline, give results complementary to antibodies when used as organocatalysts for aldol eactions between aldehydes and α-alkoxyacetones driving regioselectively to anti/syn-1,2-diols. The formation of the iso-regioisomer is suppressed using α-hydroxyacetone in DMSO at rt, achieving the corresponding anti-1,2-diol with ee’s up to 85%. For α-alkoxyacetones (methoxy, benzyloxy, and tert-butyldimethylsilyloxy), the highest regio- and dia...

  5. Preparation and surface active properties of oxypropylated diol monoesters of fatty acids with an amide oxime terminal group

    Directory of Open Access Journals (Sweden)

    Eissa, A. M.F.

    1994-10-01

    Full Text Available Locally produced non-edible oil, namely, rice bran oil (R.B.O. was utilized as starting materials for preparing new nonionic surfactant. Oxypropylated diol monoesters of linoleic and rice bran oil fatty acids were prepared. Also amide oxime derivatives were obtained. Surface active properties of these compounds were measured. Under neutral condition amide eximes served as nonionic surfactants and their properties were similar to other oxypropylated monoesters.

    Se ha utilizado un aceite no comestible de producción local, denominado, aceite de salvado de arroz (R.B.O. como materia prima para la preparación de nuevos tensioactivos no iónicos. Se prepararon diol monoésteres oxipropilados de ácido linoleico y ácidos grasos de aceite de salvado de arroz. También se obtuvieron los derivados de amido oxima. Se midieron las propiedades de tensión superficial de estos compuestos. Bajo condiciones neutras las amido eximas sirvieron como tensioactivos no iónicos y sus propiedades fueron similares a los de otros monoésteres oxipropilados.

  6. Superparamagnetic Ironoxide Nanoparticles via Ligand Exchange Reactions: Organic 1,2-Diols as Versatile Building Blocks for Surface Engineering

    Directory of Open Access Journals (Sweden)

    Robert Sachsenhofer

    2008-09-01

    Full Text Available A method for the preparation of ligand-covered superparamagnetic iron oxide nanoparticles via exchange reactions is described. 1,2-diol-ligands are used to provide a stable binding of the terminally modified organic ligands onto the surface of γ-Fe2O3-nanoparticles (r∼4 nm. The 1,2-diol-ligands are equipped with variable terminal functional groups (i.e., hydrogen bonding moieties, azido- bromo-, fluorescent moieties and can be easily prepared via osmium tetroxide-catalyzed 1,2-dihydroxylation reactions of the corresponding terminal alkenes. Starting from octylamine-covered Î��-Fe2O3-nanoparticles, ligand exchange was effected at 50∘C over 24–48 hours, whereupon complete ligand exchange is taking place as proven by thermogravimetric (TGA- and IR-spectroscopic measurements. A detailed kinetic analysis of the ligand exchange reaction was performed via TGA analysis, demonstrating a complete ligand exchange after 24 hours. The method offers a simple approach for the generation of various γ-Fe2O3-nanoparticles with functional organic shells in a one-step procedure.

  7. Deep sequencing-based transcriptome profiling analysis of Chlamys farreri exposed to benzo[a]pyrene.

    Science.gov (United States)

    Cai, Yuefeng; Pan, Luqing; Hu, Fengxiao; Jin, Qian; Liu, Tong

    2014-11-10

    Whole-genome transcriptome measurements are pivotal for characterizing molecular mechanisms of chemicals and predicting toxic classes, such as genotoxicity and carcinogenicity, from in vitro and in vivo assays. We analyzed the dynamic defense transcriptome responsive to Chlamys farreri upon exposure to benzo[a]pyrene (BaP) using a digital gene expression (DGE) approach. Following exposure, 251 and 177 genes were up-regulated, and 142 and 300 genes were down-regulated at 3 days post-exposure and 10 days post-exposure, respectively. The differentially expressed genes were related to toxicological response, oxidative stress and the metabolism of proteins and fats. Of these genes, most genes up-regulated at the early stage of exposure tended to be constantly down-regulated at the later stage whereas the landscape of the up- or down-regulated genes differed significantly at the two time points investigated. Functional enrichment analyses show that RNA-seq yields more insight into the biological mechanisms related to the toxic effects caused by BaP, i.e., two to fivefold more affected pathways and biological processes. Besides, we observed a change in the expression of ten genes which are important and differentially-expressed detoxification-related genes, and this was subsequently confirmed via quantitative real-time PCR. Our results provide evidence that RNA-seq is a powerful tool for toxicology and is capable of generating novel and valuable information at the transcriptome level for characterizing deleterious effects caused by BaP. PMID:25194896

  8. Effect of ageing on benzo[a]pyrene extractability in contrasting soils

    International Nuclear Information System (INIS)

    Highlights: • In vitro assessment of B[a]P in contaminated soils using 4 different methods. • An exponential kinetic model fits well with the extractability data. • Fitting parameter and 14C residue correlates with key soil properties. • Fractionation of B[a]P was obtained based on extractability by extractants. - Abstract: Changes in benzo[a]pyrene (B[a]P) extractability over 160 days ageing in four contrasting soils varying in organic matter content and clay mineralogy were investigated using dichloromethane: acetone 1:1 (DCM/Ace), 60 mM hydroxypropyl-β-cyclodextrin (HPCD) solution, 1-butanol (BuOH) and Milli-Q water. The B[a]P extractability by the four methods decreased with ageing and a first-order exponential model could be used to describe the kinetics of release. Correlation of the kinetic rate constant with major soil properties showed a significant effect of clay and sand contents and pore volume fraction (<6 nm) on sequestration of the desorbable fraction (by HPCD) and the water-extractable fraction. Analysis of 14C-B[a]P in soils after ageing showed a limited loss of B[a]P via degradation. Fractionation of B[a]P pools associated with the soil matrix was analysed according to extractability of B[a]P by the different extraction methods. A summary of the different fractions is proposed for the illustration of the effect of ageing on different B[a]P-bound fractions in soils. This study provides a better understanding of the B[a]P ageing process associated with different fractions and also emphasises the extraction capacity of the different methods employed

  9. Effect of the Apulia air quality plan on PM10 and benzo(apyrene exceedances

    Directory of Open Access Journals (Sweden)

    L. Trizio

    2016-03-01

    Full Text Available During the last years, several exceedances of PM10 and benzo(apyrene limit values exceedances were recorded in Taranto, a city in southern Italy included in so-called areas at high risk of environmental crisis because of the presence of a heavy industrial district including the largest steel factory in Europe. A study of these critical pollution events showed a close correlation with the wind coming from the industrial site to the adjacent urban area. During 2011, at monitoring sites closes to the industrial area, at least the 65% of PM10 exceedances were related to wind day conditions (characterized by at least 3 consecutive hours of wind coming from 270-360±2deg with an associated speed higher than 7 m/s. For this reason, in 2012 an integrated environmental permit and a regional air quality plan were enacted to reduce pollutant emissions from industrial plants. A study of PM10 levels registered during windy days was performed during critical episodes of pollution highlighting that the difference between windy days and no windy days’ concentrations reduces from 2012 to 2014 in industrial site. False negative events (verified ex-post by observed meteorological data not identified by the forecast model - did not show a significant influence on PM concentration: PM10 values were comparable and sometimes lower than windy days levels. It is reasonable that the new scenario with a relevant reduction emissions form Ilva plant reduced the pollutants contribution from industrial area, contributing to PM10 levels decrease, also in false negative events.

  10. Effect of ageing on benzo[a]pyrene extractability in contrasting soils

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Luchun [CERAR-Centre for Environmental Risk Assessment and Remediation and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Naidu, Ravi, E-mail: Ravi.Naidu@newcastle.edu.au [CERAR-Centre for Environmental Risk Assessment and Remediation and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Liu, Yanju; Palanisami, Thavamani; Dong, Zhaomin; Mallavarapu, Megharaj [CERAR-Centre for Environmental Risk Assessment and Remediation and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Semple, Kirk T. [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2015-10-15

    Highlights: • In vitro assessment of B[a]P in contaminated soils using 4 different methods. • An exponential kinetic model fits well with the extractability data. • Fitting parameter and {sup 14}C residue correlates with key soil properties. • Fractionation of B[a]P was obtained based on extractability by extractants. - Abstract: Changes in benzo[a]pyrene (B[a]P) extractability over 160 days ageing in four contrasting soils varying in organic matter content and clay mineralogy were investigated using dichloromethane: acetone 1:1 (DCM/Ace), 60 mM hydroxypropyl-β-cyclodextrin (HPCD) solution, 1-butanol (BuOH) and Milli-Q water. The B[a]P extractability by the four methods decreased with ageing and a first-order exponential model could be used to describe the kinetics of release. Correlation of the kinetic rate constant with major soil properties showed a significant effect of clay and sand contents and pore volume fraction (<6 nm) on sequestration of the desorbable fraction (by HPCD) and the water-extractable fraction. Analysis of {sup 14}C-B[a]P in soils after ageing showed a limited loss of B[a]P via degradation. Fractionation of B[a]P pools associated with the soil matrix was analysed according to extractability of B[a]P by the different extraction methods. A summary of the different fractions is proposed for the illustration of the effect of ageing on different B[a]P-bound fractions in soils. This study provides a better understanding of the B[a]P ageing process associated with different fractions and also emphasises the extraction capacity of the different methods employed.

  11. Alterations of rat liver mitochondrial oxidative phosphorylation and calcium uptake by benzo[a]pyrene

    International Nuclear Information System (INIS)

    We report that oxidative phosphorylation and Ca2+ uptake processes are enhanced in liver mitochondria isolated from benzo[a]pyrene (B[a]P)-treated rats. The carcinogen did not affect either the respiratory control index or the Ca2+ control ratio. B[a]P treatment increased the oxidation rate of several substrates that donate electrons at the level of all three coupling sites, either the ADP- or Ca2+-stimulated rates or those observed after ADP or Ca2+ exhaustion. However, the efficiency of energy coupling was maintained because both ADP/O and Ca2+/site ratios remained unchanged. The electron flow through NADH-oxidase, NADH-duroquinone reductase, NADH-juglone reductase, NADH-cytochrome c reductase, succinate-cytochrome c reductase, and cytochrome c oxidase was enhanced by B[a]P; however, succinate dehydrogenase activity was not affected. All these effects depended on the time post B[a]P administration, with a greater increase close to 48 h after administration of the carcinogen. The contents of cytochromes b, c1, and a + a3 from liver mitochondria, especially those isolated 48 h after B[a]P, were also significantly increased, although cytochrome c levels was just lightly increased 24 h after B[a]P treatment. These results suggest that B[a]P treatment stimulates mitochondrial respiration by increasing the level of several components of the mitochondrial respiratory chain. This may reflect mitochondrial adaptation to the cellular energy requirements of cell division in the neoplastic transformation process

  12. The aryl hydrocarbon receptor nuclear translocator (Arnt) is required for tumor initiation by benzo[a]pyrene

    OpenAIRE

    Shi, Shengli; Yoon, Diana Y.; Hodge-Bell, Kimberly C.; Bebenek, Ilona G.; Whitekus, Michael J.; Zhang, Ruixue; Cochran, Alistair J.; Huerta-Yepez, Sara; Yim, Sun-Hee; Gonzalez, Frank J; Jaiswal, Anil K.; Hankinson, Oliver

    2009-01-01

    Benzo[a]pyrene (B[a]P) is a ligand for the aryl hydrocarbon receptor (Ahr). After binding ligand, Ahr dimerizes with the aryl hydrocarbon receptor nuclear translocator (Arnt) protein, and the dimer upregulates the transcription of Cyp1a1, Cyp1b1 and other enzymes involved in the metabolic activation of B[a]P. Arnt null mice die in utero. Mice in which Arnt deletion occurs constitutively in the epidermis die perinatally. In the current study, mice were developed in which the Arnt gene could be...

  13. Degradation of benzo[a]pyrene in an experimentally contaminated paddy soil by vetiver grass (Vetiveria zizanioides).

    Science.gov (United States)

    Li, H; Luo, Y M; Song, J; Wu, L H; Christie, P

    2006-01-01

    A pot experiment was conducted to study the effect of growing vetiver grass on the biodegradation of benzo[a]pyrene (B[a]P) under glasshouse conditions. Plant biomass, microbial biomass C and degradation of B[a]P were determined. B[a]P disappeared faster in the plant treatments than in unplanted controls. Disappearance of B[a]P was accompanied by an increase in soil microbial biomass C. Vetiver grass may promote the biodegradation of B[a]P under flooded conditions by plant roots by stimulating the microbial biomass. Microbial biomass was the main factor affecting dissipation of B[a]P under flooded conditions. PMID:16528581

  14. Electrochemiluminescent Arrays for Cytochrome P450-Activated Genotoxicity Screening. DNA Damage from Benzo[a]pyrene Metabolites

    OpenAIRE

    Hvastkovs, Eli G.; So, Minjeong; Krishnan, Sadagopan; Bajrami, Besnik; Tarun, Maricar; Jansson, Ingela; Schenkman, John B.; Rusling, James F.

    2007-01-01

    Arrays suitable for genotoxicity screening are reported that generate metabolites from cytochrome P450 enzymes (CYPs) in thin-film spots. Array spots containing DNA, various human cyt P450s, and electrochemiluminescence (ECL) generating metallopolymer [Ru(bpy)2PVP10]2+ were exposed to H2O2 to activate the enzymes. ECL from all spots was visualized simultaneously using a CCD camera. Using benzo[a]pyrene as a test substrate, enzyme activity for producing DNA damage in the arrays was found in th...

  15. Real-Time Raman Monitoring during Photocatalytic Epoxidation of Cyclohexene over V-Ti/MCM-41 Catalysts

    Directory of Open Access Journals (Sweden)

    Hsiang-Yu Chan

    2015-03-01

    Full Text Available A series of V- and/or Ti-loading MCM-41 catalysts are successfully synthesized with a hydrothermal method. The photocatalytic and thermal epoxidations of cyclohexene in the presence of tert-butyl hydroperoxide (t-BuOOH were investigated with real-time monitored by NIR-Raman spectroscopy. It suggests that both V- and Ti-loading can be responsible for the cyclohexene epoxidation. Moreover, the complementary behavior of V- and Ti-loading may be related to a similar role of activation. Interestingly, the progress of the photo-epoxidation on V0.25Ti2/MCM-41 photocatalyst was monitored by changes in intensity of the characteristic Raman bands without interference from the UV-light irradiation. The result, for the first time, reveals that cyclohexene was directly photo-epoxidized to 1,2-epoxycyclohexane by t-BuOOH during the reaction. A possible mechanism of cyclohexene photo-epoxidation is also proposed for this study.

  16. UV-assisted removal of inactive peroxide species for sustained epoxidation of cyclooctene on anatase TiO2.

    Science.gov (United States)

    Yang, Changjun; Lang, Xianjun; Ma, Wanhong; Chen, Chuncheng; Ji, Hongwei; Zhao, Jincai

    2014-05-19

    Epoxidation of olefins with H2O2 is one of the most important reactions in organic synthesis. We found that anatase TiO2 can be a good catalyst for the epoxidation of cyclooctene with H2O2 at room temperature. However, the catalyst deactivated quickly in the presence of excess amount of H2O2 because of the formation of inactive side-on Ti-η(2)-peroxide species on the surface of TiO2, the presence of which was confirmed by isotope-labelled resonance UV Raman spectroscopy and kinetics studies. Interestingly, the epoxidation reaction could be dramatically accelerated under irradiation of UV light with λ≥350 nm. This phenomenon is attributed to the photo-assisted removal of the inactive peroxide species, through which the active sites on the surface of anatase TiO2 are regenerated and the catalytic epoxidation of cyclooctene with H2O2 is resumed. This finding provides an alternative for sustained epoxidation reactions on TiO2 at room temperature. Moreover, it also has significant implications on the deactivation pathway and possible solutions in Ti-based heterogeneous catalysis or photocatalysis. PMID:24764202

  17. Total synthesis of cis-hydroazulene sesquiterpenes. Base-induced and -directed elimination and rearrangement reactions of perhydronaphthalene-1,4-diol monosulfonate esters.

    NARCIS (Netherlands)

    Jenniskens, L.H.D.

    1992-01-01

    The total synthesis of a number of cis-fused hydroazulene sesquiterpenes is described in this thesis. In this synthetic study, ample attention is paid to the mechanistic aspects of the base- induced and -directed rearrangement and elimination reactions of perhydronaphthalene-1,4-diol monosulfonate e

  18. (E-2-((4R,5R-5-((Benzyloxymethyl-2,2-dimethyl-1,3-dioxolan-4-ylbut-2-ene-1,4-diol

    Directory of Open Access Journals (Sweden)

    Carlos R. Carreras

    2010-04-01

    Full Text Available The synthesis of (E-2-((4R,5R-5-((benzyloxymethyl-2,2-dimethyl-1,3-dioxolan-4-ylbut-2-ene-1,4-diol by a one-step reduction of the appropriate 2-substituted butenolide is reported. Product characterization was carried out by IR, 1H NMR, 13C NMR, MS, elemental analysis and optical rotation.

  19. Crystallization and preliminary X-ray analysis of molecular chaperone-like diol dehydratase-reactivating factor in ADP-bound and nucleotide-free forms

    International Nuclear Information System (INIS)

    The molecular chaperone-like reactivating factor for adenosylcobalamin (coenzyme B12) dependent diol dehydratase was crystallized in ADP-bound and nucleotide-free forms. Preliminary X-ray analysis indicated that crystals are orthorhombic and diffract to 2.0 Å. Adenosylcobalamin (coenzyme B12) dependent diol dehydratase (EC 4.2.1.28) catalyzes the conversion of 1,2-diols and glycerol to the corresponding aldehydes. It undergoes mechanism-based inactivation by glycerol. The diol dehydratase-reactivating factor (DDR) reactivates the inactivated holoenzymes in the presence of adenosylcobalamin, ATP and Mg2+ by mediating the release of a damaged cofactor. This molecular chaperone-like factor was overexpressed in Escherichia coli, purified and crystallized in the ADP-bound and nucleotide-free forms by the sandwich-drop vapour-diffusion method. The crystals of the ADP-bound form belong to the orthorhombic system, with space group P212121 and unit-cell parameters a = 83.26, b = 84.60, c = 280.09 Å, and diffract to 2.0 Å. In the absence of nucleotide, DDR crystals were orthorhombic, with space group P212121 and unit-cell parameters a = 81.92, b = 85.37, c = 296.99 Å and diffract to 3.0 Å. Crystals of both forms were suitable for structural analysis

  20. Fluorine-containing terpene analogs. IV. 9,9,9,10,10,10-Hexafluoro-p-menthane-1,8-diol (hexafluoroterpine)

    Energy Technology Data Exchange (ETDEWEB)

    Zalesskaya, I.M.; Fialkov, Yu.A.; Parakhnenko, A.I.; Yagupol' skii, I.M.

    1988-03-10

    The oxidation of trans-e,e-4-(2-hydroxyperfluoroisopropyl)cyclohexanol with pyridinium chlorochromate gave the corresponding cyclohexanone. The reaction of this product with methylmagnesium iodide gave cis- and trans-9,9,9,10,10,10-hexafluoro-p-menthane-1,8-diol, which is fluorinated analog of natural terpine.

  1. Alternating polyesteramides based on 1,4-butylene terephthalamide: 3. Alternating polyesteramides based on mixtures of linear diols (4NTm,p)

    NARCIS (Netherlands)

    Serrano, P.J.M.; Werff, van der B.A.; Gaymans, R.J.

    1998-01-01

    Strictly alternating polyesteramides consisting of 1,4-butylene terephthalamide diester and mixtures of aliphatic diols have been synthesised in the melt in the presence of a titanium catalyst. To increase the molecular weight a solid state post condensation was applied. The composition was determin

  2. Effects of 3-beta-diol, an androgen metabolite with intrinsic estrogen-like effects, in modulating the aquaporin-9 expression in the rat efferent ductules

    Directory of Open Access Journals (Sweden)

    Hess Rex A

    2006-10-01

    Full Text Available Abstract Background Fluid homeostasis is critical for normal function of the male reproductive tract and aquaporins (AQP play an important role in maintenance of this water and ion balance. Several AQPs have been identified in the male, but their regulation is not fully comprehended. Hormonal regulation of AQPs appears to be dependent on the steroid in the reproductive tract region. AQP9 displays unique hormonal regulation in the efferent ductules and epididymis, as it is regulated by both estrogen and dihydrotestosterone (DHT in the efferent ductules, but only by DHT in the initial segment epididymis. Recent data have shown that a metabolite of DHT, 5-alpha-androstane-3-beta-17-beta-diol (3-beta-diol, once considered inactive, is also present in high concentrations in the male and indeed has biological activity. 3-beta-diol does not bind to the androgen receptor, but rather to estrogen receptors ER-alpha and ER-beta, with higher affinity for ER-beta. The existence of this estrogenic DHT metabolite has raised the possibility that estradiol may not be the only estrogen to play a major role in the male reproductive system. Considering that both ER-alpha and ER-beta are highly expressed in efferent ductules, we hypothesized that the DHT regulation of AQP9 could be due to the 3-beta-diol metabolite. Methods To test this hypothesis, adult male rats were submitted to surgical castration followed by estradiol, DHT or 3-beta-diol replacement. Changes in AQP9 expression in the efferent ductules were investigated by using immunohistochemistry and Western blotting assay. Results Data show that, after castration, AQP9 expression was significantly reduced in the efferent ductules. 3-beta-diol injections restored AQP9 expression, similar to DHT and estradiol. The results were confirmed by Western blotting assay. Conclusion This is the first evidence that 3-beta-diol has biological activity in the male reproductive tract and that this androgen metabolite has

  3. The genotoxic effects of benzo[a]pyrene and methamidophos on black porgy evaluated by comet assay

    Science.gov (United States)

    Liu, Rixian; Hong, Huasheng; Wang, Xinhong; Wang, Kejian; Wang, Chunguang

    2005-12-01

    In this study, two common pollutants (benzo[a]pyrene and methamidophos) in marine environment were tested by comet assay for their inducement of in vivo genotoxic effect to the blood cells of black porgy ( Acanthopagrus schlegeli). The fish was exposed to 2 μg/L of benzo[a]pyrene (BaP) and methamidophos, and their mixture. The assay was performed on whole blood at 2 h, 5 h, 24 h and 96 h exposure intervals. A significant increase in DNA damage was observed in each treatment with the pollutants. Additive effect of BaP and methamidophos was also found in the experiment. However, the decrease ratios of DNA damage for 5 h and 96 h exposure interals compared with 2 h and 24 h exposure ones, respectively, were noticed. This phenomenon may be explained by the function of repairing process via enzyme cytochrome P450 in the animal. Evidence of the genotoxicity of organophosphorus pesticides (OPs) and polynuclear aromatic hydrocarbons (PAHs) on marine fish are discussed in this paper.

  4. Determination of Benzo(a)pyrene in Malaysian commercialized coffee powder using solid phase extraction and gas chromatography

    International Nuclear Information System (INIS)

    Roasting is a critical process in coffee production as it enables the development of flavor and aroma. Benzo[a]pyrene (BaP) is a non desirable product of incomplete combustion at temperatures between 300 and 600 degree Celsius and may be produced during roasting step. In this study, selected samples of roasted coffee powder were analysed for BaP. Extraction of BaP was achieved using C18 solid phase extraction (SPE) prior to analysis by gas chromatography. Calibration curve prepared with concentrations ranged between 3 - 50 ppm showed good linearity with r = 0.999. The limit of detection (LOD) was 0.25 ppm and the limit of quantification (LOQ) was 0.85 ppm. Recovery of BaP obtained from spiked sample (3 ppm) was 88.7 % with RSD (n=3) of 5.4 %. Benzo[a]pyrene was detected in all samples, at level ranging from 0.14 to 0.62 ppb. (author)

  5. The genotoxic effects of benzo[a]pyrene and methamidophos on black porgy evaluated by comet assay

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In this study, two common pollutants (benzo[a]pyrene and methamidophos) in marine environment were tested by comet assay for their inducement of in vivo genotoxic effect to the blood cells of black porgy (Acanthopagrus schlegeli). The fish was exposed to 2 μg/L of benzo[a]pyrene (BaP) and methamidophos, and their mixture. The assay was performed on whole blood at 2 h, 5 h, 24 h and 96 h exposure intervals. A significant increase in DNA damage was observed in each treatment with the pollutants. Additive effect of BaP and methamidophos was also found in the experiment. However, the decrease ratios of DNA damage for 5 h and 96 h exposure interals compared with 2 h and 24 h exposure ones, respectively, were noticed. This phenomenon may be explained by the function of repairing process via enzyme cytochrome P450 in the animal. Evidence of the genotoxicity of organophosphorus pesticides (OPs) and polynuclear aromatic hydrocarbons (PAHs) on marine fish are discussed in this paper.

  6. Selective Propene Epoxidation on Immobilized Au6-10 Clusters: The Effect of Hydrogen and Water on Activity and Selectivity

    DEFF Research Database (Denmark)

    Lee, Sungsik; Molina, Luis M.; López, María J.;

    2009-01-01

    Epoxidation made easy: Subnanometer gold clusters immobilized on amorphous alumina result in a highly active and selective catalyst for propene epoxidation. The highest selectivity is found for gas mixtures involving oxygen and water, thus avoiding the use of hydrogen. Ab initio DFT calculations ...

  7. Strategic use of nickel(0)-catalyzed enyne-epoxide reductive coupling towards the synthesis of (−)-cyatha-3,12-diene

    OpenAIRE

    Sparling, Brian A.; Simpson, Graham L.; Jamison, Timothy F.

    2009-01-01

    Various situations are explored in which the nickel(0)-catalyzed enyne-epoxide reductive coupling was utilized to access key intermediates towards the total synthesis of (−)-cyatha-3,12-diene (1). Enantioenriched 3,5-dien-1-ols with a variety of functionality were obtained in a straightforward manner from easily accessible 1,3-enynes and terminal epoxides.

  8. A common carcinogen benzo[a]pyrene causes neuronal death in mouse via microglial activation.

    Directory of Open Access Journals (Sweden)

    Kallol Dutta

    Full Text Available BACKGROUND: Benzo[a]pyrene (B[a]P belongs to a class of polycyclic aromatic hydrocarbons that serve as micropollutants in the environment. B[a]P has been reported as a probable carcinogen in humans. Exposure to B[a]P can take place by ingestion of contaminated (especially grilled, roasted or smoked food or water, or inhalation of polluted air. There are reports available that also suggests neurotoxicity as a result of B[a]P exposure, but the exact mechanism of action is unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using neuroblastoma cell line and primary cortical neuron culture, we demonstrated that B[a]P has no direct neurotoxic effect. We utilized both in vivo and in vitro systems to demonstrate that B[a]P causes microglial activation. Using microglial cell line and primary microglial culture, we showed for the first time that B[a]P administration results in elevation of reactive oxygen species within the microglia thereby causing depression of antioxidant protein levels; enhanced expression of inducible nitric oxide synthase, that results in increased production of NO from the cells. Synthesis and secretion of proinflammatory cytokines were also elevated within the microglia, possibly via the p38MAP kinase pathway. All these factors contributed to bystander death of neurons, in vitro. When administered to animals, B[a]P was found to cause microglial activation and astrogliosis in the brain with subsequent increase in proinflammatory cytokine levels. CONCLUSIONS/SIGNIFICANCE: Contrary to earlier published reports we found that B[a]P has no direct neurotoxic activity. However, it kills neurons in a bystander mechanism by activating the immune cells of the brain viz the microglia. For the first time, we have provided conclusive evidence regarding the mechanism by which the micropollutant B[a]P may actually cause damage to the central nervous system. In today's perspective, where rising pollution levels globally are a matter of grave concern, our

  9. Genetic variants in microsomal epoxide hydrolase and N-acetyltransferase 2 in susceptibility of IBD in the Danish population

    DEFF Research Database (Denmark)

    Ernst, Anja; Andersen, Vibeke; Østergaard, Mette;

    induce or sustain an immune response. Changes in detoxification of substances that causes epithelial damage may confer susceptibility to IBD. Hence, polymorphic enzymes involved in the detoxification processes may be risk factors of IBD. Methods. The two biotransformation enzymes microsomal epoxide...... hydrolase and N-acetyltransferase 2 were genotyped using TaqMan based Real-Time PCR in 388 patients with Crohn's disease (CD), 565 patients with ulcerative colitis (UC) and 796 healthy Danish controls. Results. No association was found between low microsomal epoxide hydrolase activity or slow N......-acetyltransferase 2 acetylator status and IBD. An association between high activity of microsomal epoxide hydrolase and disease diagnosis before age 40 in CD with an OR of 2.2(1.1- 4.2) P=0.02) was found. No other phenotypic associations were found for the two enzymes and IBD, regarding age at onset, disease location...

  10. Cloning, expression, purification, crystallization and preliminary X-ray studies of epoxide hydrolases A and B from Mycobacterium tuberculosis

    International Nuclear Information System (INIS)

    Epoxide hydrolases A (Rv3617) and B (Rv1938), detoxification enzymes from M. tuberculosis, have been cloned, expressed, purified and crystallized. Crystals of Rv3617 and Rv1938 diffracted to 3.0 and 2.1 Å resolution, respectively. Mycobacterium tuberculosis epoxide hydrolases A and B, corresponding to open reading frames Rv3617 and Rv1938, are detoxification enzymes against epoxides. The recombinant forms of these enzymes have been expressed in Escherichia coli and purified to homogeneity. Diffraction-quality crystals of Rv3617 and Rv1938 were obtained by the hanging-drop vapour-diffusion technique. Crystals of Rv3617 and Rv1938 diffracted to 3.0 and 2.1 Å resolution, respectively, at the ALS synchrotron at Berkeley, CA, USA

  11. Monolayer behaviour of chiral compounds at the air-water interface: 4-hexadecyloxy-butane-1,2-diol

    DEFF Research Database (Denmark)

    Rietz, R.; Rettig, W.; Brezesinski, G.;

    1996-01-01

    Monolayers of the pure S-enantiomer (x(S) = 1) and of two mixtures x(S) = 0.75 and x(S) = 0.5 (racemate) of 4-hexadecyloxy-butane-1,2-diol (C16H33-O-CH2-CH2-CHOH-CH2OH) (HOBD) have been studied at the air-water interface by thermodynamic measurements, fluorescence microscopy and X-ray diffraction....... The isotherms depend only slightly on chirality. Above the transition pressure pi(c) condensed domains with a polygonal shape are formed. In all cases the domains start to destabilize from the notch. The branches of the S-enantiomer turn only clockwise, whereas domains of the mixtures show branches...

  12. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amides

    Directory of Open Access Journals (Sweden)

    Angélica Díaz

    2014-04-01

    Full Text Available Poly(alkylene dicarboxylates constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amides derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  13. Assessing the oxidative potential of isoprene-derived epoxides and secondary organic aerosol

    Science.gov (United States)

    Kramer, Amanda J.; Rattanavaraha, Weruka; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.; Lin, Ying-Hsuan

    2016-04-01

    Fine particulate matter (PM2.5) is known to contribute to adverse health effects, such as asthma, cardiopulmonary disease, and lung cancer. Secondary organic aerosol (SOA) is a major component of PM2.5 and can be enhanced by atmospheric oxidation of biogenic volatile organic compounds in the presence of anthropogenic pollutants, such as nitrogen oxides (NOx) and sulfur dioxide. However, whether biogenic SOA contributes to adverse health effects remains unclear. The objective of this study was to assess the potential of isoprene-derived epoxides and SOA for generating reactive oxygen species (ROS) in light of the recent recognition that atmospheric oxidation of isoprene in the presence of acidic sulfate aerosol is a major contributor to the global SOA burden. The dithiothreitol (DTT) assay was used to characterize the ROS generation by the isoprene-derived epoxides, trans-β-isoprene epoxydiol (trans-β-IEPOX) and methacrylic acid epoxide (MAE), and their hydrolysis products, the 2-methyltetrol diastereomers (2-MT), 2-methylglyceric acid (2-MG), their organosulfate derivatives, as well as an isoprene-derived hydroxyhydroperoxide (ISOPOOH). In addition, ROS generation potential was evaluated for total SOA produced from photooxidation of isoprene and methacrolein (MACR) as well as from the reactive uptake of trans-β-IEPOX and MAE onto acidified sulfate aerosol. The high-NOx regime, which yields 2-MG-, MAE- and MACR-derived SOA has a higher ROS generation potential than the low-NOx regime, which yields 2-MT, IEPOX- and isoprene-derived SOA. ISOPOOH has an ROS generation potential similar to 1,4-naphthoquinone (1,4-NQ), suggesting a significant contribution of aerosol-phase organic peroxides to PM oxidative potential. MAE- and MACR-derived SOA show equal or greater ROS generation potential than reported in studies on diesel exhaust PM, highlighting the importance of a comprehensive investigation of the toxicity of isoprene-derived SOA.

  14. Optimum Operating Conditions for Epoxidation Reaction of Jojoba and Castor Oils

    Directory of Open Access Journals (Sweden)

    El-Adly R. A

    2014-03-01

    Full Text Available The goal of this paper is to determine the best set of parameters such as, glacial acetic acid to ethylenic unsaturation mole ratio (acid/ethylene, hydrogen peroxide to ethylenic unsaturation mole ratio (H2O2/ethylene and temperature on epoxidation conversion based on experimental results, with respect to time. The effect of these parameters has been studied in a separate set of experiments. Their ranges were as follows: 0.2-0.8Wt%, 0.75-3Wt%, and 40oC-80oC respectively. Six models have been introduced to indicate the effect of these three variables on conversion for both jojoba and castor oil, and the prediction abilities of the resultant models were tested. Regression analysis is used to extract the introduced non linear models. In addition, two new correlations have been introduced to incorporate all the studied variables and their effect on conversion simultaneously for both jojoba and castor oil. An optimization program has been introduced to determine the optimum operating conditions for maximum conversion for both jojoba and castor oil. The study shows that, the maximum conversion for epoxidized jojoba oil (66% could be achieved at acid/ethylene ratio: 0.4, H2O2/ethylene ratio: 1.44; temp: 66.5 and time is 8hr. While the maximum conversion for epoxidized castor oil (53.24% could be achieved at acid/ethylene ratio: 0.37; H2O2/ethylenes ratio: 1.32; temp: 61 and time is 8hr. the model results are strongly agreed with the experimental results.

  15. Rapid epoxidation of palm acid oil with lipase action under microwave irradiation

    International Nuclear Information System (INIS)

    In view of growing environmental concerns and tightened regulations over contaminants and pollution in the environment in recent years, calls for biodegradable and nontoxic vegetable oil-based lubricants are abound. They have very low volatility due to the higher molecular weight of the triacylglycerol molecule and a narrow range of viscosity changes with temperature. Polar ester groups in the molecule are able to adhere to metal surfaces, and therefore, possess good boundary lubrication properties. In addition, vegetable oils have high solubilising power for polar contaminants and additive molecules. However, vegetable oils show poor oxidative and thermal stability primarily due to the presence of unsaturation. The presence of ester functionality also renders these oils susceptible to hydrolytic breakdown. The proposed modification of the vegetable oils is an important manner to obtain potentially useful products using a renewable feedstock. In designing a green process to effectively carry out the epoxidation reaction, we report herein, an inexpensive, practical, safe and environmentally friendly method to epoxidize palm acid oil under extremely mild conditions. This work highlights the increased reaction rate of the epoxidation process when microwave irradiation is introduced. The starting material used is Palm Acid Oil, a by-product of the alkali refining process of palm oil. Acid oil can serve as an inexpensive raw materials and are very good substitute for neat vegetable oil such as palm oil for the production of bio lubricant. It is high in Free Fatty Acids (FFA) and is the ideal material for the epoxidation process due to the importance of FFAs in producing peroxy-acids as an oxygen carrier. The double bonds the triglycerides are reacted with a per acid, generated for safety reasons in situ using hydrogen peroxide. Novozym 435 acts as the catalyst in the process and with its good selectivity, the occurrence of by-products is controlled. The method and

  16. Studies on the Executionof Models Used in Iron Foundry From Epoxidic Resins

    Directory of Open Access Journals (Sweden)

    Cinca - Ionel Lupinca

    2006-10-01

    Full Text Available The epoxidic resins are materials frequently used in the execution of the models used in iron foundry. This materials can replace casily wood or aluminium in the execution of the models needed in series productions, having better resistance properties and the high dimensional precision. The properties of these resins are obtained from the completion of the epoxibifunctional molecules with supplements. This paper establishes the result of mixing the two components, as well as the supplements used to improve the mechanic and the technological properties.

  17. A new environmental friendly clay catalyst for one-pot coiodination and epoxidation of alkenes

    International Nuclear Information System (INIS)

    The commercial Brazilian clay Bentonit BrasgelTM was characterized by chemical and textural analyses, XRD, and 27Al and 29Si MAS-NMR, that indicated the presence of α-quartz and smectite as clay-minerals. This natural clay proved to be an efficient catalyst for the conversion of alkenes into epoxides by the reaction with iodine/water followed by in situ addition of KOH in hexane (80-91 % yield). Similar results were obtained with Bentonit BrasgelTM intercalated with Ag(I). (author)

  18. How the Proximal Pocket May Influence the Enantiospecificities of Chloroperoxidase-Catalyzed Epoxidations of Olefins

    Science.gov (United States)

    Morozov, Alexander N.; Chatfield, David C.

    2016-01-01

    Chloroperoxidase-catalyzed enantiospecific epoxidations of olefins are of significant biotechnological interest. Typical enantiomeric excesses are in the range of 66%–97% and translate into free energy differences on the order of 1 kcal/mol. These differences are generally attributed to the effect of the distal pocket. In this paper, we show that the influence of the proximal pocket on the electron transfer mechanism in the rate-limiting event may be just as significant for a quantitatively accurate account of the experimentally-measured enantiospecificities. PMID:27517911

  19. Vitamin K 2,3-epoxide reductase: the basis for stereoselectivity of 4-hydroxycoumarin anticoagulant activity.

    OpenAIRE

    Thijssen, H. H.; Baars, L. G.; Vervoort-Peters, H. T.

    1988-01-01

    1. The administration of S-warfarin (1 mg kg-1 i.v.) to rats that were pre-loaded 48 h before with tracer doses (6 micrograms) of 14C-labelled R- or S-warfarin caused the plasma levels of these compounds to increase. This is due to the substitution of the microsomal (vitamin K 2,3-epoxide (K0) reductase) bound R- or S-[14C]-warfarin by the unlabelled 4-hydroxycoumarin administered. The rate of reappearance was 3-4 fold higher for R- than for S-warfarin; t1/2 of release: 1.2 +/- 0.04 and 3.7 +...

  20. Studies on whole cell fluorescence-based screening for epoxide hydrolases and Baeyer-Villiger monooxygenases

    Energy Technology Data Exchange (ETDEWEB)

    Bicalho, Beatriz; Chen, Lu S.; Marsaioli, Anita J. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica]. E-mail: anita@iqm.unicamp.br; Grognux, Johann; Reymond, Jean-Louis [University of Berne (Switzerland). Dept. of Chemistry and Biochemistry

    2004-12-01

    Biocatalysis reactions were performed on microtiter plates (200 {mu}L) aiming at the utilization of fluorogenic substrates (100 {mu}mol L{sup -1}) for rapid whole cell screening for epoxide hydrolases (EHs) and Baeyer-Villiger monooxygenases (BVMOs). A final protocol was achieved for EHs, with 3 new enzymatic sources being detected (Agrobacterium tumefaciens, Pichia stipitis, Trichosporom cutaneum). The fluorogenic assay for BVMO did not work as expected. However, an approach to possible variables involved (aeration; pH) provided the first detection of a BVMO activity in T. cutaneum. (author)