The chemiluminescence of gallic acid by hydrogen peroxide had completely inhibited by the presence of ascorbate. After ascorbate had disappeared by oxidation, chemiluminescence returned. The concentration of gallic acid was virtually unchanged by presence of ascorbate, but started to decrease after the disappearance of ascorbate. This might be attributable to the rapid reduction of quinone, which was the first product of the chemiluminescence reactions, to gallic acid by ascorbate or the donation of proton to the phenoxy radical from ascorbate to stop the chemiluminescence reaction at the first stage. The effects of ascorbate on the chemiluminescence of other polyphenols depended on their oxidation rate.   

Colonies of tissues of crown-gall of vipers grass (Scorzonera hispanica) cultivated for three successive transitions on a medium with and without ascorbic acid additions to a concentration of 10/sup -5/ were used in the study. Ooses of x rays at 500, 1000, 1500, and 2000 r were given. The colonies with ascorbic acid showed a smaller growth inhibition than those without, thus showing that the ascorbic acid exerts a radioprotective effect. (T.R. H.)

The degradation kinetics of catechin in aqueous solution in the presence of L-ascorbic acid or octanoyl L-ascorbate, which was synthesized through the immobilized-lipase-catalyzed condensation of ascorbic and octanoic acids in acetonitrile, and of various organic acids were expressed by a first-order equation. The stability of catechin was reduced by the addition of ascorbic acid or octanoyl ascorbate at a concentration of 10 mmol/L, although the rate constant, k, for degradation in the presence of ascorbic acid or octanoyl ascorbate decreased with increasing citric acid concentration. Malic, lactic and sorbic acids were also effective for decelerating the oxidative degradation by ascorbic acid and octanoyl ascorbate, but their suppressive effects on the degradation of catechin differed between the solutions containing ascorbic acid and octanoyl ascorbate. This indicates that octanoyl ascorbate acts on catechin with a different mechanism from that of ascorbic acid.   

The objective of this study was to evaluate the antifungal and antioxidant activities of curcumin, ascorbic acid and the mixture of these two compounds. For the antifungal assay, the minimum inhibitory concentrations (MIC) were determined using Candida strains (ATCC and clinical isolates). Curcumin alone inhibited growth of Candida albicans yeast cells, whereas ascorbic acid did not present effects. However, when the mixture of ascorbic acid and curcumin was assayed to determine the association of the two compounds, the curcumin MIC decreased 5- to 10-fold. In the antioxidant assays, the sum of the alone activities of curcumin and ascorbic acid were lower than the activity of the two-compound mixture. This study highlights the importance of the association between two common antioxidants i...

The antioxidant activities of saturated fatty acid esters of L-ascorbic acid were studied in the oxidations of soybean phosphatidylcholine liposomes in aqueous dispersions aiming at elucidating their action as antioxidants in the liposomal membranes, especially the effects of number and length of the fatty acid ester side chains at either 6- or both 5- and 6-positions. Ascorbic acid esters were found to act as radical-scavenging antioxidants in the oxidations initiated by either aqueous free radical attacking from outside of the membrane or by lipophilic radical generated within the membranes. They inhibited the oxidation cooperatively with ?-tocopherol in the membranes and reduced the rate of ?-tocopherol consumption, their sparing effects on ?-tocopherol being greatest for the monoesters and for the esters with the shortest fatty acid chains within the diester group. It was concluded that the intramembrane and intermembrane mobilities of ascorbic acid esters decreased with increasing number and length of fatty acid chains.   

Experiments on rats were made to examine the effect of vitamin B1, pantothenic and ascorbic acids on the acetylation system and some characteristics of protein metabolism under chronic exposure to phenol. Inhibition of phenol vapours led to inhibition of the acetylation on the 105th day of the experiment, to accumulation of pyruvic acid by the blood and diurnal urine, to elevation of cholesterol content in the blood serum. The total content of protein and protein fractions in the blood serum remained unchanged. Additional vitaminization of the animals with thiamine (150 micrograms), calcium pantothenate (650 micrograms) or with their mixture containing ascorbic acid (2 mg) resulted in normalization of the test characteristics of carbohydrate and fat metabolism. The data obtained and the clinical trials carried out by the authors suggest introduction of the physiological doses of thiamine, calcium pantothenate and ascorbic acid into the diet of the workers in order to prevent phenol poisonings more effectively.

After physically disrupting cell contacts, apoptosis of bursal cells of Fabricius was induced during in vitro cultivation. The percentage of apoptotic cells increased with incubation time and approximately 70% cells represented apoptosis after 6 hr of incubation. The induction of apoptosis was significantly inhibited by treatment of the cells with ascorbic acid (vitamin C), but not with trolox, a vitamin E analog. An intense DNA ladder pattern was shown at 6 hr post-isolation, which is a biochemical hallmark of apoptosis. Treatment of the cells with ascorbic acid inhibited the DNA fragmentation, but trolox did not. To monitor the intracellular production of reactive oxygen species (ROSs), the intensity of fluorescence emitted from DCFH-DA was measured. The intensity of fluorescence from cells incubated for 0.5-2 hr was approximately 2-fold higher than that from cells at 0 hr. The relative intensity of fluorescence decreased immediately after the addition of ascorbic acid to the cells. The intensity from the cells treated with ascorbic acid was 20-30% of that from the control cells at each incubation time. For trolox, the intensity was 50-70% of that from the control cells at each 1 to 2 hr incubation time. When ROSs-induced lipid peroxidation was assessed using cis-parinaric acid (PnA) as a monitor molecule, lipid peroxidation was found to occur in the control cells after isolation of the bursal cells. Treatment of the cells with trolox reduced lipid peroxidation, but treatment with ascorbic acid enhanced peroxidation.   

The aim of this work was to compare the preventing capacity of quercetin with Cu/Zn superoxide dismutase (Cu/Zn SOD), ascorbic acid and glutathione on nitric oxide (NO)-induced relaxation in mouse gastric fundus. Furthermore, the effects of the quercetin on the tissue level of total oxidant and antioxidant was investigated. Nitrergic stimulation (4Hz, 25V, 0.1ms, 10s-train) and exogenous NO (10?M) induced relaxation. Pyrogallol (10?M), hydroquinone (100?M) and LY83583 (6-Anilino-quinolin-5,8-quinone, 5?M) inhibited nitrergic relaxations. The inhibition observed with pyrogallol, hydroquinone and LY83583 was prevented by quercetin (0.1?M). Also, ascorbic acid (500?M), glutathione (100?M) and Cu/Zn SOD (100U/ml) prevented the inhibitory effect of superoxide anion generators on the relaxation to nitrergic stimulation and NO. Diethyldithiocarbamic acid (DETCA; 8mM) inhibited nitrergic relaxations. DETCA-induced inhibition on nitrergic stimulation and NO-induced relaxation was prevented by quercetin, ascorbic acid, glutathione or Cu/Zn SOD. DETCA plus pyrogallol, hydroquinone or LY83583 strengthened the inhibition on the relaxations. Also, pre-treatment with quercetin, ascorbic acid and glutathione prevented the inhibitory effect of DETCA plus LY-83583 on the relaxation to nitrergic stimulation and NO but Cu/Zn SOD did not prevent this inhibition. Also, quercetin increased tissue total antioxidant capacity and decreased tissue oxidant level and oxidative stress index in DETCA-treatment group. These results indicate that quercetin has antioxidant effect and protects NO from endogenous superoxide anion-driven inactivation and enhances its biological activity, suggesting that quercetin may scavenge superoxide anion in a Cu/Zn SOD, glutathione or ascorbic acid-inhibitable manner. PMID:23085029

Inhibition of quorum sensing by enterotoxin-producing strains of Clostridium perfringens was investigated. Autoinducer-2 (AI-2) activity was measured in the presence and absence of ascorbic acid (vitamin C; concentrations ranging from 10 to 300 mM), an AI-2 analogue. Subsequent effects on AI-2 pro...

Synthesis of new surfactants with antioxidant properties was carried out from ascorbic acid and different fatty amines. Characterization of physicochemical properties of these new compounds indicated a classical behavior of cationic surfactants. Antioxidant properties, estimated using methyl linoleate oxidation inhibition and DPPH methods, were close to that of ascorbic acid tested in the same conditions. These compounds were investigated in the formulation of wood preservation mixtures containing propiconazole, a widely used fungicide, and compared to the formulation obtained with an industrial nonionic surfactant. Biological tests were carried out under laboratory conditions to evaluate the ability of these formulations to protect beech wood blocks exposed to Coriolus versicolor, a white...

The main purpose of this paper was to study the effect of selected additives, NaCl, NaHSO3, ascorbic acid, cysteine and allicin, on acrylamide (AA) formation in asparagine/fructose (Asn/Fru) and asparagine/glucose (Asn/Glc) by microwave processing. Our results showed that NaHSO3 and cysteine had the best reduction rate on AA formation, but the browning would be influenced by the addition of these additives. Ascorbic acid is another good inhibitor for AA formation both in Asn/Fru and Asn/Glc model systems, but the browning would be inhibited by the high concentration of ascorbic acid. Natural antioxidants are attractive candidates for the development of effective inhibitors for AA formation. In the present study, allicin effectively reduced AA formation and achieved a maximum reduction rate...

A pomegranate extract (PE) from the rind containing 90% ellagic acid was tested for its skin-whitening effect. PE showed inhibitory activity against mushroom tyrosinase in vitro, and the inhibition by the extract was comparable to that of arbutin, which is a known whitening agent. PE, when administered orally, also inhibited UV-induced skin pigmentation on the back of brownish guinea pigs. The intensity of the skin-whitening effect was similar between guinea pigs fed with PE and those fed with L-ascorbic acid. PE reduced the number of DOPA-positive melanocytes in the epidermis of UV-irradiated guinea pigs, but L-ascorbic acid did not. These results suggest that the skin-whitening effect of PE was probably due to inhibition of the proliferation of melanocytes and melanin synthesis by tyrosinase in melanocytes. PE, when taken orally, may be used as an effective whitening agent for the skin.   

  Bovine lactoferrin (LF) and lactoferricin B (LFcin B), an antimicrobial peptide derived from bovine LF, inhibited thiobarbituric acid-reactive substance (TBARS) formation in a iron/ascorbate-induced liposomal phospholipid peroxidation system. The inhibition of TBARS formation occurred with N-acylated 9-mer peptides with a core sequence of LFcin B and, compared to LFcin B, their antioxidant effect was clearly observed at a concentration almost 100 times lower.   

We have previously reported that radon inhalation activates anti-oxidative functions and inhibits carbon tetrachloride (CCl(4))-induced hepatopathy. It has also been reported that antioxidant vitamins can inhibit CCl(4)-induced hepatopathy. In the current study, we examined the comparative efficacy of treatment with radon, ascorbic acid and ?-tocopherol on CCl(4)-induced hepatopathy. Mice were subjected to intraperitoneal injection of CCl(4) after inhaling approximately 1000 or 2000 Bq/m(3) radon for 24 h, or immediately after intraperitoneal injection of ascorbic acid (100, 300, or 500 mg/kg bodyweight) or ?-tocopherol (100, 300, or 500 mg/kg bodyweight). We estimated the inhibitory effects on CCl(4)-induced hepatopathy based on hepatic function-associated parameters, oxidative damage-associated parameters and histological changes. The results revealed that the therapeutic effects of radon inhalation were almost equivalent to treatment with ascorbic acid at a dose of 500 mg/kg or ?-tocopherol at a dose of 300 mg/kg. The activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver were significantly higher in mice exposed to radon than in mice treated with CCl(4) alone. These findings suggest that radon inhalation has an anti-oxidative effect against CCl(4)-induced hepatopathy similar to the anti-oxidative effects of ascorbic acid or ?-tocopherol due to the induction of anti-oxidative functions. PMID:23111757

The aqueous extract of leaf (LE), fruit (FE) and seed (SE) of Moringa oleifera was assessed to examine the ability to inhibit the oxidative DNA damage, antioxidant and anti-quorum sensing (QS) potentials. It was found that these extracts could significantly inhibit the OH-dependent damage of pUC18 plasmid DNA and also inhibit synergistically with trolox, with an activity sequence of LE > FE > SE. HPLC and MS/MS analysis was carried out, which showed the presence of gallic acid, chlorogenic acid, ellagic acid, ferulic acid, kaempferol, quercetin and vanillin. The LE was with comparatively higher total phenolics content (105.04 mg gallic acid equivalents (GAE)/g), total flavonoids content (31.28 mg quercetin equivalents (QE)/g), and ascorbic acid content (106.95 mg/100 g) and showed better antioxidant activity (85.77%), anti-radical power (74.3), reducing power (1.1 ascorbic acid equivalents (ASE)/ml), inhibition of lipid peroxidation, protein oxidation, OH-induced deoxyribose degradation, and scavenging power of superoxide anion and nitric oxide radicals than did the FE, SE and standard alpha-tocopherol. Eventually, LE and FE were found to inhibit violacein production, a QS-regulated behavior in Chromobacterium violaceum 12472. PMID:19425184

Ascorbic acid levels of seven species of digenetic trematodes, living under different environmental conditions in fish and mammals were determined colorimetrically. Ascorbic acid levels ranged from 0.312 mg/100 g fresh weight in Gastrothylax crumenifer to 5.070 mg/100 g fresh weight in Fasciola indica. Low levels of ascorbic acid were detected in the rumen parasites and in Isoparorchis hypselobagri. In contrast the liver parasites were found to have relatively high ascorbic acid levels. PMID:7395312

Melanin production by S. algae BrY occurred during late/post-exponential growth in lactate-basal-salts liquid medium supplemented with tyrosine or phenylalanine. The antioxidant ascorbate inhibited melanin production, but not production of the melanin precursor, homogentisic acid. In the absence of ascorbate, melanin production was inhibited by the 4-hydroxyplenylpyruvate dioxygenase inhibitor, sulcotrione and Fe(II) (>0.2mM). These data support the hypothesis that pigment production by S. algae BrY was a result the conversion of tyrosine or phenylalanine to homogentisic acid which was excreted, auto-oxidized and self-polymerized to form pyomelanin. The inverse relationship between Fe(II) concentration and pyomelanin production has implications that pyomelanin may play a role in iron assimilation under Fe(II) limiting conditions.

Abstract Treatments to inhibit browning of fresh-cut apples were investigated. The color (L*), the browning potential and polyphenol oxidase (PPO) activity of fresh-cut apples (Golden Delicious, Scarlet Spur and Granny Smith) were evaluated throughout cold storage. Antibrowning agents (citric and ascorbic acid) and calcium chloride resulted in a reduction of browning and deterioration of fresh-cut apples stored at 4C for 5 days under normal atmospheric conditions. During storage, PPO activity increased and was inhibited by the use of citric and ascorbic acids. These antibrowning agents helped to maintaining the color of fresh-cut apples during storage. On the contrary, the use of 1-methylcyclopropene was not effective to prevent the color deterioration of the apple slices from the first da...

Abstract Prophenoloxidase (PPO) was purified from Galleria mellonella L. A 67-fold purification of the proenzyme with 352% yield was achieved by using a Sepharose 4B-L-tyrosine-p-amino benzoic acid affinity column. The purified enzyme was migrated as a single band on SDS-polyacrylamide gel electrophoresis. K(m) and V(max) values were 0.017 M and 1430.45 EU for catechol. Inhibition of PPO was investigated with inhibitors such as p-aminobenzoic acid, etyleneglycol, and ascorbic acid. Among them, ascorbic acid showed the strongest inhibitory activity with IC(50) value of 2.94 ?M. The current paper represents new strategies for the biological control of the Galleria mellonella L. insect. PMID:22780216

The aqueous extract of leaf (LE), fruit (FE) and seed (SE) of Moringa oleifera was assessed to examine the ability to inhibit the oxidative DNA damage, antioxidant and anti-quorum sensing (QS) potentials. It was found that these extracts could significantly inhibit the OH-dependent damage of pUC18 plasmid DNA and also inhibit synergistically with trolox, with an activity sequence of LE>FE>SE. HPLC and MS/MS analysis was carried out, which showed the presence of gallic acid, chlorogenic acid, ellagic acid, ferulic acid, kaempferol, quercetin and vanillin. The LE was with comparatively higher total phenolics content (105.04mg gallic acid equivalents (GAE)/g), total flavonoids content (31.28mg quercetin equivalents (QE)/g), and ascorbic acid content (106.95mg/100g) and showed better antioxida...

In the present study, we carried out a systematic research on relative antioxidant activity of aqueous leaf extract of Stevia rebaudiana. The DPPH activity of aqueous leaf extract (20, 40, 50, 100 and 200mg/ml) was increased in a dose dependent manner, which was found in the range of 40.00-72.37% as compared to ascorbic acid 64.26-82.58%. The IC50 values of aqueous extract and ascorbic acid in DPPH radical scavenging assay were obtained to be 83.45 and 26.75mg/ml, respectively. Measurement of total phenolic content of the aqueous leaf extract of S. rebaudiana was achieved using Folin-Ciocalteau reagent containing 56.73mg/g of phenolic content, which was found significantly potent when compared to reference standard gallic acid. The aqueous extract also inhibited the hydroxyl radical, nitri...

It has been suggested that some food components, such as bioflavonoids, affect the bioavailability of ascorbic acid in humans. Since little is known in Japan about the effective intake of this dietary requirement, we tested young Japanese males after the ingestion of commercial ascorbic acid or acerola (Malpighia emarginata DC.) juice to compare the quantities absorbed and excreted. Healthy Japanese subjects received a single oral dose of ascorbic acid solution (50, 100, 200 or 500 mg) and received distilled water as a reference at intervals of 14 d or longer. All subjects were collected blood and urine until 6 h after ingestion and evaluated for time-dependent changes in plasma and urinary ascorbic acid levels. Predictably, the area under the curve (AUC) values in plasma and urine after ingestion increased dose-dependently. Next, each subject received diluted acerola juice containing 50 mg ascorbic acid. Likewise, their plasma and urinary ascorbic acid concentrations were measured. In plasma, the AUC value of ascorbic acid after ingestion of acerola juice tended to be higher than that from ascorbic acid alone. In contrast, the urinary excretion of ascorbic acid at 1, 2 and 5 h after ingestion of acerola juice were significantly less than that of ascorbic acid. These results indicate that some component of acerola juice favorably affected the absorption and excretion of ascorbic acid.   

This paper provides information on the effects of toxic concentrations of zinc sulfate (ZnSO/sub 4/.7H/sub 2/O) on the growth and metabolism of rice Oryza sativa L. seedlings. Root growth inhibition was always more pronounced than was shoot growth inhibition. Root growth was completely inhibited at 40 m M concentration, whereas the magnitude of reduction of shoot length was only 56% at this concentration. Gibberellic acid (GA/sub 3/) was partially capable of relieving zinc inhibition. The activities of peroxidase, IAA oxidase and ascorbic acid oxidase of seedlings increased in response to zinc addition, whereas catalase and IAA synthetase decreased. All the hydrolyzing enzymes, viz., ..cap alpha..-amylase and phytase of endosperm together with RNase and ATPase of the embryo, showed distinct inhibition from the control, the exception being endosperm RNase which was stimulated under zinc treatment. 50 references, 6 figures.

Abstract:- While use of synthetic antioxidants (such as butylated hydroxytoluene and butylated hydroxyanisole) to maintain the quality of ready-to-eat food products has become commonplace, consumer concern regarding their safety has motivated the food industry to seek natural alternatives. Phenolic antioxidants can inhibit free radical formation and/or interrupt propagation of autoxidation. Fat-soluble vitamin E (-tocopherol) and water-soluble vitamin C (L-ascorbic acid) are both effective in the appropriate matrix. Plant extracts, generally used for their flavoring characteristics, often have strong H-donating activity thus making them extremely effective antioxidants. This antioxidant activity is most often due to phenolic acids (gallic, protocatechuic, caffeic, and rosmarinic acids), ph...

Several novel 1,2,4-triazole and imidazole l-ascorbic acid (1, 2, 3, 5, 6 and 9) and imino-ascorbic acid (4, 7 and 8) derivatives were prepared and evaluated for their inhibitory activity against hepatitis C virus (HCV) replication and human tumour cell proliferation. Compounds 6 and 9 exerted the most pronounced cytostatic effects in all tumour cell lines tested, and were highly selective for human T-cell acute lymphoblastic leukaemia cells (CEM/0) with IC50s of 10+-4 and 7.3+-0.1mM, respectively. Unlike compound 9, compound 6 showed no toxicity in human diploid fibroblasts. One of the possible mechanisms of action of compound 6 accounting for observed cytostatic activity towards haematological malignancies might be inhibition of inosine monophosphate dehydrogenase (IMPDH) activity, a key...

The effect of chitosan, glucose and chitosan-glucose complex (CGC) on the microbial and postharvest quality of shiitake (Lentinus edodes) mushroom stored at 4+-1degreeC for 16days was investigated. Mushroom weight loss, respiration rate, firmness, ascorbic acid, total soluble solids, microbial and sensory quality were measured. The results indicate that treatment with CGC coating maintained tissue firmness, inhibited increase of respiration rate, reduced microorganism counts, e.g., pseudomonads, yeasts and moulds, compared to uncoated control mushroom. The efficiency was better than that of chitosan or glucose coating treatment. In addition, CGC coating also delayed changes in the ascorbic acid and soluble solids concentration. Sensory evaluation proved the efficacy of CGC coating by maint...

(/sup 3/H)-5-Hydroxytryptamine ((/sup 3/H)-5-HT) decomposes rapidly when exposed to air in solution at physiological pH if antioxidants are not present. The decomposition products appear to bind to two saturable sites on brain membranes (apparent Kd values = 1-2 and 100-1000 nM). This binding mimics ''specific'' ligand/receptor binding in that it is inhibited by 10 microM unlabeled 5-HT. This inhibition is not competitive, but rather is due to the prevention of (/sup 3/H)-5-HT breakdown by excess unlabeled 5-HT. Unlike genuine ligand/receptor binding, the binding of (/sup 3/H)-5-HT breakdown products is essentially irreversible and does not display a tissue distribution consistent with binding to authentic 5-HT receptors. (/sup 3/H)-5-HT decomposition can be eliminated by the inclusion of 0.05 to 5 mM ascorbic acid. At these concentrations ascorbic acid is not deleterious to reversible (/sup 3/H)-5-HT binding. When (/sup 3/H) 5-HT exposure to air occurs in the presence of brain membranes, the apparent antioxidant activity of brain membranes themselves affords protection against (/sup 3/H)-5-HT degradation equal to ascorbic acid. This protection is effective below final (/sup 3/H)-5-HT concentrations of 10 nM. Above 10 nM (/sup 3/H)-5-HT, addition of ascorbic acid or other antioxidants is necessary to avoid the occurrence of additional low affinity (apparent Kd = 15-2000 nM) binding sites that are specific but nonetheless irreversible. When care is taken to limit (/sup 3/H)-5-HT oxidation, the only reversible and saturable specific binding sites observed are of the 5-HT1 high affinity (Kd = 1-2 nM) type. Radioligand oxidation artifacts may be involved in previous reports of low affinity (Kd = 15-250 nM) (/sup 3/H)-5-HT binding sites in brain membrane preparations.

Roxarsone (4-hydroxy-3-nitro-phenylarsonic acid) and p-arsanilic acid (4-aminophenylarsonic acid) are feed additives widely used in the broiler and swine industry. This study evaluated the inhibitory effect of roxarsone, p-arsanilic, and other phenylarsonic compounds on the activity of acetate- and H(2)-utilizing methanogenic microorganisms. Roxarsone, p-arsanilic, and 4-hydroxy-3-aminophenylarsonic acid (HAPA) inhibited acetoclastic and hydrogenotrophic methanogens when supplemented at concentrations of 1mM, and their inhibitory effect increased sharply with incubation time. Phenylarsonic acid (1mM) inhibited acetoclastic but not H(2)-utilizing methanogens. HAPA, a metabolite from the anaerobic biodegradation of roxarsone, was found to be sensitive to autooxidation by oxygen. The compound (2.6mM) caused low methanogenic inhibition (only 14.2%) in short-term assays of 12h when autooxidation was prevented by supplementing HAPA solutions with ascorbate. However, ascorbate-free HAPA solutions underwent spontaneous autooxidation in the presence of oxygen, leading to the formation of highly inhibitory compounds. These results confirm the microbial toxicity of organoarsenic compounds, and they indicate that biotic as well as abiotic transformations can potentially impact the fate and microbial toxicity of these contaminants in the environment. PMID:19889499

Ascorbate-apatite and ascorbate-fibroblast growth factor-2 (FGF-2)-apatite composite layers were successfully formed on anodically oxidized Ti rods clinically used for external fixation by a one-step procedure at 25 degrees C, using a metastable supersaturated calcium phosphate solution supplemented with l-ascorbic acid phosphate magnesium salt n-hydrate (AsMg) and FGF-2. The AsMg-apatite and AsMg-FGF-2-apatite composite layers were evaluated in vitro using fibroblastic NIH3T3 and osteoblastic MC3T3-E1 cells. The AsMg-FGF-2-apatite composite layer markedly enhanced the NIH3T3 cell proliferation and procollagen type capital I, Ukrainian gene expression. Without FGF-2, the AsMg-apatite composite layer whose ascorbate content was 3.64+/-1.27microgcm(-2) obviously enhanced osteoblastic proliferation and differentiation. However, the AsMg-FGF-2-apatite composite layers whose FGF-2 contents were from 0.15+/-0.03 to 0.31+/-0.04microgcm(-2) inhibited osteoblastic differentiation in vitro. Thus, the AsMg-FGF-2-apatite composite layer should be precipitated on the surface of external fixators attached to skin and soft tissue. On the other hand, the AsMg-apatite composite layer should be precipitated at the part attached to bone tissue. PMID:19375998

A flow-sonochemiluminescence (SCL) method that offers a fast and simple alternative to the antioxidant capacity analysis is described. Reactive oxygen species (ROS) is generated reagentlessly and in situ in pH 7.4 phosphate buffer saline by ultrasound irradiating. Luminol reacts with the ROS to give SCL. The presence of antioxidant quenches the ROS, which in turn quenches the SCL. By quantifying SCL inhibition, the antioxidant capacity measurement can be achieved. Antioxidants including uric acid, l-ascorbic acid, tannic acid, l-cysteine, citric acid, salicylic, dl-sorbol and glutathione, are selected to test the presented method. Linear relationships between the quenched SCL intensity and antioxidant concentration, IC50 (half-inhibition concentration) of each antioxidant are obtained. Ant...

There is suggestive evidence that a low status of ascorbic acid in camels enhances their risk for infectious diseases. This study was carried out to disclose the role of reproduction, if any, in affecting ascorbic acid status. The associations between the reproductive cycle and ascorbic acid contents in plasma and leukocytes were studied in Sudanese camels browsing on local vegetation. Ascorbic acid status was found to be lowest during pregnancy and highest during lactation. Estrus versus non-estrus was associated with high vitamin C status. Brucellosis-positive camels showed decreased levels of ascorbic acid in plasma and leukocytes. Possibly, the phases of non-estrus and pregnancy in camels invoke an increased susceptibility to infectious diseases due to a lower ascorbic acid status.

The influence of exogenous ascorbic acid (AsA) on oxidative phosphorylation was studied using wheat seedling roots. Treatment of them with AsA stimulated the rates of oxygen consumption and the heat production and caused a decrease of the respiratory coefficient. The increase in respiration was prevented by inhibitors of ascorbate oxidase, diethyldithiocarbamate (DEDTC), and of cytochrome oxidase, cyanide (KCN). Exogenous AsA sharply stimulated the rate of oxygen consumption of roots when complexes I and III of the mitochondrial electron transport chain were inhibited by rotenone and antimycin A, respectively, while the rates of heat production did not change significantly. It is concluded that AsA is a potent energy substrate, which can be used in conditions of failing I and III complexes in the mitochondrial electron transport chain.

Wavelet transformation was applied as an elimination method of influence by an interfering substance on an amperometric biosensor. The current responses of a bi-enzyme type lactose biosensor in a solution containing both lactose and ascorbic acid were analyzed by wavelet transformation. The power spectrum density for ascorbic acid was detected selectively at around 0.125 Hz. The current component due to ascorbic acid was eliminated at 98% from the current response of the biosensor by wavelet transformation.   

The aqueous extract of galls from Terminalia chebula Retz. (Combretaceae) was fractionated on Diaion and refractionated on octadecyl silica column. Six phenolic compounds were isolated and identified as gallic acid (1), punicalagin (2), isoterchebulin (3), 1,3,6-tri-O-galloyl-?-D-glucopyranose (4), chebulagic acid (5) and chebulinic acid (6). All of the compounds showed stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and melanin inhibitory activities than ascorbic acid, butylated hydroxytoluene, ?-tocopherol, arbutin and kojic acid, the reference compounds. Gallic acid (1) exhibited inhibitory activity against nitric oxide production in lipopolysaccharide-activated macrophages. However, all isolated compounds exhibited less activity than the reference compounds in mushroom tyrosinase inhibition and human tumour cytotoxicity assays. This study has demonstrated that the phenolic compounds isolated from galls of T. chebula might contribute significantly due to their antioxidant and whitening activities. PMID:21108118

The influence of L-ascorbic acid at 40 °C incubation on the subfragment-1 and rod regions, prepared by chymotryptic digestion of myosin, and myosin was investigated by SDS–polyacrylamide gel electrophoresis and transmission electron microscopy respectively. It was observed that L-ascorbic acid acted more readily on the subfragment-1 region of myosin. Further, circular dichroism measurement indicated that L-ascorbic acid did not affect the structure of myosin. These results suggest that L-ascorbic acid acts more readily on the myosin subfragment-1 region and promotes the gelation of myosin without producing a conformational change in this protein.   

Abstract Nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, have been associated with the damage to the gastrointestinal tract. One proposed mechanism of injury to the gastrointestinal mucosa by NSAIDs is oxygen radical-dependent microvascular injury. There is reasonable evidence to support the benefit of the addition of ascorbic acid, an ingredient with antioxidant properties, to moderate the adverse gastrointestinal (GI) effects of aspirin. Pharmacokinetic data have demonstrated that aspirin and ascorbic acid combination therapy can assist in mitigating the decrease in levels of ascorbic acid secondary to aspirin monotherapy. Endoscopic evaluation has demonstrated that the addition of ascorbic acid to aspirin significantly improves Lanza scores and rates of blood loss when...

Flavonoids and ascorbic acid are antioxidants usually consumed together in foods, taking this into account, the antiradical capacity of mixtures of ascorbic acid with some representative flavonoids (flavanones, chalcones and flavonols) against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) was evaluated. Antiradical capacities of naringin, naringenin, hesperidin, hesperetin, naringin chalcone, naringin dihydrochalcone, rutin and quercetin were measured alone and in different combinations with ascorbic acid. Experimental and theoretical values of antiradical activities for these mixtures as well as the values obtained in sequential reactions were compared in order to determine synergistic or antagonistic effects. Among the different ascorbic acid-flavonoid combinations analyzed only the m...

This study was undertaken to assess in vitro lipid peroxidation inhibitions and anti-radical activities of methanolic, chloroform, ethyl acetate and water fractions of Mangifera indica leaf. Inhibition of Fe(2+)-induced lipid peroxidation (LPO) in egg, brain, and liver homogenates, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl (OH-) radical scavenging activities were evaluated. Total phenol was assessed in all fractions, and the reducing power of methanolic fraction was compared to gallic acid and ascorbic acid. The results showed that Fe2+ induced significant lipid peroxidation (LPO) in all the homogenates. Ethyl acetate fraction showed the highest percentage inhibition of LPO in both egg yolk (68.3%) and brain (66.3%), while the aqueous fraction exerted the highest inhibition in liver homogenate (89.1%) at a concentration of 10 microg/mL. These observed inhibitions of LPO by these fractions were higher than that of ascorbic acid used as a standard. The DPPH radical scavenging ability exhibited by ethyl acetate fraction was found to be the highest with IC50 value of 1.5 microg/mL. The ethyl acetate and methanolic fractions had the highest OH- radical scavenging ability with the same IC50 value of 5 microg/mL. The total phenol content of ethyl acetate fraction was the highest with 0.127 microg/mg gallic acid equivalent (GAE). The reductive potential of methanolic fraction showed a concentration-dependent increase. This study showed that inhibition of LPO and the DPPH and OH- radicals scavenging abilities of Mangifera indica leaf could be related to the presence of phenolic compounds. Therefore, the ethyl acetate fraction of the leaf may be a good source of natural antioxidative agent. PMID:21485698

Ascorbic acid added to the basal medium increased the growth response of Lactobacillus casei in folic acid standards. The effect in the serum extracts was not marked, resulting in lowered serum folic acid estimations. However, results obtained on prolonged incubation were similar whether ascorbic ac...

The feeding of glucoascorbic acid, an analog of ascorbic acid, to mice and cotton rats caused the production of a condition exhibiting many of the changes characteristic of scurvy as seen in susceptible species. The condition was not prevented or cured by ascorbic acid, but was cured by removal of ...

Ethylene regulates many aspects of plant growth and development; however, its effect on the behavior of the stomata is still largely obscure. Here, the association between ethylene inhibition of darkness-induced stomatal closure and hydrogen peroxide (H2O2) levels in Vicia faba guard cells was studied. Like ascorbic acid (ASA), the most important reducing substrate for H2O2 removal, catalase (CAT), one of H2O2-scavenging enzymes, and diphenylene iodonium (DPI), an inhibitor of the H2O2-generating enzyme NADPH-oxidase, both ethylene-releasing compound 2-chloroethylene phosphonic acid (ethephon, ETH) and 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, were found to inhibit stomatal closure by darkness and to reduce H2O2 levels in guard cells, indicating that...

The effectiveness of maleic hydrazide, chloroisopropylcarbamate and other chemicals for inhibition of sprouting in potatoes is discussed. Sprout inthibition by irradiation is discussed with regard to: effects of radiation on ability of tubers to form wound periderm; effective radiation dose levels; and effects of radiation on respiration and content of sugars and ascorbic acid. In regard to wholesomeness of treated potatoes, residues caused by chemical sprout inhibitors and effects of radiation on vitamin and starch content are considered. Long-term feeding studies in rats, mice, and monkeys were conducted in Japan. A discussion is given of steps toward commercialization of irradiated potatoes in Hungary, Germany, Canada, the USSR, and Japan. (HLW)

Silver nanoparticles were prepared by chemical reduction method using chitosan as stabilizer and ascorbic acid as reducing agent in this work. The silver/chitosan nanocomposites were characterized in terms of their particle sizes and morphology by using UV spectrophotometer, nano-grainsize analyzer, and transmission electron microscopy. Antibacterial activities of these nanocomposites were carried out for Staphylococcus aureus and Escherichia coli. The silver nanoparticles exhibited significantly inhibition capacity towards these bacteria. Detailed studies on the biocompatibility of the silver/chitosan nanocomposites were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cell adhesion test. The results indicated that these silver/chitosan nanocomposites...

The rate of /sup 3/H-dopamine decomposition was determined in buffers and in neostriatal membrane preparations that are commonly used in binding experiments. The rate of decomposition of /sup 3/H-dopamine was inhibited considerably by the membrane preparation and by ascorbic acid. Under conditions in which the binding of /sup 3/H-dopamine is routinely measured in neostriatal membrane preparations, there was almost no /sup 3/H-dopamine decomposition. The data would seem to suggest that the routine addition of very high concentrations of antioxidants is unnecessary when /sup 3/H-dopamine binding is being determined.

1. Cells of the fresh water diatom Navicula pelliculosa may be grown in a mineral medium containing a low concentration of silicon. When transferred to a fresh silicate solution and incubated under non-growing conditions such deficient cells rapidly take up silicon from the medium. 2. The utilization of silicon is an aerobic process. 3. When deficient cells are washed with distilled water or saline, their ability to utilize silicon is impaired whereas respiration is unaffected. 4. The ability of washed cells to take up silicon can be partially restored with sulfate or ascorbic acid, and is completely restored by Na(2)S, Na(2)S(2)O(3), glutathione, l-cysteine, dl-methionine, or ascorbic acid plus sulfate. 5. The sulfhydryl reagent, CdCl(2), inhibits silicon utilization of unwashed cells at concentrations which do not affect respiration. This inhibition similarly is reversed by glutathione or cysteine. 6. However, sodium iodoacetate or sodium arsenite inhibits respiration and silicon utilization at the same concentrations. 7. The silicon taken up by deficient cells is deposited at the cell surface as a thickening of the existing silica frustules. 8. Sulfhydryl groups in the cell membrane may be involved in silicon uptake by diatoms. PMID:13163359

The rate of degradation of L-ascorbic acid in solution has been investigated under varying conditions, such as temperature, level of dissolved oxygen, pH, amino acids, sugars and processing conditions. Changes in pH between pH 1.5 and 7.0 accelerate L-ascorbic acid degradation. The most important factor that determines its stability is storage temperature, on which the rate of degradation of L-ascorbic acid is directly dependent. Similarly, the deleterious effect of variables such as oxygen and pH are influenced by temperature. Therefore, low temperature storage is imperative in order to regard L-ascorbic acid delay. A definite role of amino acids in L-ascorbic acid degradation has not been identified. PMID:7621082

A novel heme-containing ascorbate oxidase isolated from oyster mushroom, Pleurotus ostreatus, catalyzes oxidation of ascorbic acid (Kim et al., 1996). In this report, we describe the identification of intracellular substrates of the enzyme in the mushroom. Six compounds, which can serve as substrate of the heme-containing ascorbate oxidase, were identified as L-ascorbic acid, D-erythroascorbic acid, 5-O-(alpha-D-glucopyranosyl)-D-erythroascorbic acid, 5-O-(alpha-D-xylopyranosyl)-D-erythroascorbic acid, 5-methyl-5-O-(alpha-D-gluco-pyranosyl)-D-erythroascorbic acid, and 5-methyl-5-O-(alpha-D-xylopyranosyl)-D-erythroascorbic acid. All of the compounds were oxidized at a significant rate by the heme-containing ascorbate oxidase. Oxidation of the compounds produced equimolar amounts of hydrogen peroxide per mole of substrate. PMID:19412602

The origin of oxalate in plants has received considerable attention and glycolate metabolism has been generally regarded as a prime precursor candidate although studies on the metabolism of L-ascorbic acid single out that plant constituent as well. Experiments with oxalate-accumulating plants that contain little or no tartaric acid revealed the presence of a comparable L-ascorbic acid metabolism with the exception that the cleavage products were oxalic acid and L-threonic acid or products of L-threonic acid metabolism. A reasonable mechanism for cleavage of L-ascorbic acid at the endiolic bond is found in studies on the photooxygenation of L-ascorbic acid. Presumably, analogs of L-ascorbic acid that differ only in the substituent at C4 also form a hydroperoxide in the presence of alkaline hydrogen peroxide and subsequently yield oxalic acid and the corresponding aldonic acid or its lactone. We became interested in such a possibility when we discovered that L-ascorbic acid was rare or absent in certain yeasts and fungi whereas a L-ascorbic acid analog, D-glycero-pent-2-enono- 1,4-lactone (D-erythroascorbic acid), was present. It has long been known that oxalate occurs in yeasts and fungi and its production plays a role in plant pathogenesis. As to the biosynthetic origin of fungal oxalic acid there is little information although it is generally assumed that oxaloacetate or possibly, glycolate, might be that precursor.

• Background and Aims A number of strawberry varieties were surveyed for their total ellagic acid concentration, and attempts were made to determine if ellagic acid and ascorbic acid concentrations of two strawberry cultivars could be increased by polythene reflective mulches.

The aim of the present work was the development of vaginal sponge-like dressings based on chitosan ascorbate (CS) and on hyaluronic acid sodium salt/lysine acetate (HAS) combination. Sponge-like dressings were prepared by freeze-drying and characterized for mechanical resistance and mucoadhesion. CS dressings show higher mechanical and mucoadhesion properties in comparison with HAS dressing. The enzymatic inhibition properties of the dressings were evaluated in vitro against carboxipeptidase A in view of their employment for vaginal delivery of peptidic drugs. All the dressings were able to inhibit carboxipeptidase activity; CS dressings, independently of polymer MW, completely inhibited enzyme activity. Release and penetration enhancement properties of the dressings loaded with a high mol...

The inhibitory activity of berberine on the DNA single-strand cleavage induced by hydrogen peroxide and cytochrome c was measured. Berberine effectively inhibited single-strand cleavage of DNA and its effectiveness was concentration-dependent. As the berberine concentration increased, the inhibitory activity against the DNA single-strand cleavage increased. The treatments with 1,5,10,50, and 100 ?M berberine showed 7.7,10.8,32.2,39.5, and 51.6% inhibition of DNA cleavage. This inhibitory activity of berberine against the DNA single-strand cleavage has never been reported previously. The inhibitory activity of berberine against DNA cleavage was stronger than caffeic acid and ascorbic acid. Berberine did not show strong hydroxyl radical scavenging activity, but showed strong superoxide anion radical quenching ability.   

Synopsis This study involves the evaluation of the effect of certain stabilizers, that is, citric acid (CT), tartaric acid (TA) and boric acid (BA) on the degradation of ascorbic acid (AH2) in oil-in-water cream formulations exposed to the UV light and stored in the dark. The apparent first-order rate constants (0.34-0.95--10-3-min-1 in light, 0.38-1.24--10-2-day-1 in dark) for the degradation reactions in the presence of the stabilizers have been determined. These rate constants have been used to derive the second-order rate constants (0.26-1.45--10-2-M-1-min-1 in light, 3.75-8.50- 10-3-M-1-day-1 in dark) for the interaction of AH2 and the individual stabilizers. These stabilizers are effective in causing the inhibition of the rate of degradation of AH2 both in the light and in the dark. ...

The results of the present study have shown that unoxidized linoleic acid (LA) and low density lipoprotein (LDL) suppressed free radical-induced supercoiled plasmid DNA strand breaks. Unoxidized LA suppressed DNA strand breaks induced by free radicals generated from hydrogen peroxide/Fe(II) ion, 2?-azobis(2-amidinopropane)hydrochloride (AAPH), and 4-(hydroxymethyl)benzene diazonium salt. Thiobarbituric acid reactive substances (TBARS) of LA were increased on treatment with the radical generators. The intensities of the electron spin resonance (ESR) signals of the spin adducts of the radicals were reduced by unoxidized LA. Although LA hydroperoxide caused DNA strand breaks as has already been shown, its strand breaking activity was observed only at the higher concentrations. Unoxidized LDL inhibited ascorbic acid/Cu(II) ion-, ascorbic acid/Fe(II) ion-, peroxynitrite- and AAPH-induced DNA strand breaks. The TBARS of LDL were increased by treatment with the agents. LDL oxidized with Cu(II) ion did not cause DNA strand breaks. The results indicate that the potency of the free radicals to cause DNA strand breaks was attenuated by the fatty acid and the lipoprotein through lipid peroxidation.   

The bioavailability of ascorbic acid administered to thoroughbreds by intramuscular injection was investigated. For intramuscular injection two preparations were studied, and the percentage bioavailability up to 24 h of 10 g of ascorbic acid was 95% +/- 22 in four horses and 60% in two horses with preparations A and B, respectively. Bioavailability at 24 h in three horses injected subcutaneously with 10 g of preparation B was 82%. Intramuscular injection of both preparations was apparently well tolerated while subcutaneous injection of preparation B (pH 6.0) was associated with marked irritancy. In a cross-over trial in seven thoroughbreds the effect of 13 or 15 days of oral administration of crystalline ascorbic acid (20 g) or ascorbyl palmitate (47 g) on plasma ascorbic-acid concentrations was investigated. Marked differences occurred between individuals. There was a greater increase in plasma ascorbic-acid concentration with ascorbyl palmitate compared to ascorbic acid at 6 and 24 h following administration. In two horses there was no increase in plasma ascorbic acid at 6 h following either oral preparation. The finding of lowered plasma ascorbic-acid concentrations following a period of supplementation warrants further investigation to assess its significance. PMID:2287031

1 The effect of lipid peroxidation on p-aminohippurate transport by rat kidney slices was examined. 2 Ascorbic acid and Fe2+ promoted lipid peroxidation of rat renal cortical slices in a dose-related manner. 3 Ascorbic acid (1.0 mM) and Fe2+ (0.4 mM) increased tissue water and decreased the accumula...

Efficiency was examined of microencapsulating L-ascorbic acid by polyglycerol monostearate (PGMS), and changes in the chemical and sensorial aspects of L-ascorbic acid and/or iron-fortified milk during storage were evaluated. The selected core materials were ferric ammonium sulfate and L-ascorbic acid. The highest efficiency (94.2%) of microencapsulation was found with the ratio of 5:1 as the coating to core material. The release of ascorbic acid from the microcapsules increased sharply from 1.6 to 6.7% up to 5 d of storage. The TBA value was the lowest in the milk sample with added encapsulated iron and unencapsulated L-ascorbic acid up to 5 d of storage in comparison with the other treated samples. A sensory analysis showed that most aspects were not significantly different between the control and fortified samples encapsulated with ascorbic acid after 5 d of storage. The results indicate that L-ascorbic acid microencapsulated with PGMS can be applied to fortify milk and acceptable milk products can be prepared with microencapsulated L-ascorbic acid and iron.   

Vitamin C is transported as ascorbic acid (AA) through the sodium-ascorbate cotransporters (SVCT1 and -2) and as dehydroascorbic acid (DHA) through the facilitative glucose transporters. All cells have glucose transporters and take up DHA that is trapped intracellularly by reduction and accumulated ...

The term "vitamin" is used to define a number of organic compounds that have to be obtained from different foods because the organism itself cannot synthesize them in the quantities needed to sustain life. Vitamin C is the common name for L-ascorbic acid. In humans, the principal role of this molecule is to scavenge reactive oxygen species, due to its antioxidant capacity, and to serve as cofactor for many enzymes. A deficiency of L-ascorbic acid is traditionally linked to human diseases such as scurvy. Plant foods are the principal source of L-ascorbic acid for humans. There is a high variability of L-ascorbic acid content in the various plant organs that are used for human consumption. This diversity is related to the specific functions played by L-ascorbic acid in the different plant tissues. The net content of L-ascorbic acid in plants is determined through a balance of the activities of different biosynthetic, recycling, and catabolic pathways. Here we review the importance of L-ascorbic acid for human health, the current knowledge on its metabolism and function in plants, and the efforts that have already been made by genetic modification to improve its content in plant organs used for human food. We provide a current and forward looking perspective of how plant science can contribute to improving the L-ascorbic acid content in crop species using gene transformation, quantitative trait loci and association mapping-based approaches. PMID:22890788

We investigated the formation of a new lecithin organogel composed of reverse worm-like micelles. The organogel is a mixed organic solution containing lecithin and vitamin C (i.e., ascorbic acid). The highly viscoelastic reverse worm-like micelles were formed upon addition of a small amount of ascorbic acid.   

This patent describes a stabilized radiopharmaceutial composition. It comprises: a molecule containing a radioactive iodine atom and a stabilize, selected from the group consisting of ascorbic acid, nicotinamide and its corresponding amides, or a mixture of ascorbic acid and nicotinamide and its amides, in a sufficient amount to stabilize against radiolytic decomposition.

Werner syndrome (WS) is a rare autosomal disease characterized by the premature onset of several age-associated pathologies. The protein defective in WS patients (WRN) is a helicase/exonuclease involved in DNA repair, replication, transcription and telomere maintenance. Hypoxia-inducible factor-1 (HIF-1) is a decisive element for the transcriptional regulation of genes essential for adaptation to low oxygen conditions. HIF-1 is also implicated in the molecular mechanisms of ageing. Here, we show that the cellular depletion of WRN protein (by siRNA targeting) leads to increased HIF-1 complex stabilization and activation. HIF-1 activation in the absence of WRN involves the generation of mitochondrial reactive oxygen species (mtROS) since SkQ1, a mitochondrial-targeted antioxidant, and stigmatellin, an inhibitor of mitochondrial complex III, blocked increased HIF-1 levels. Ascorbate, an essential co-factor involved in HIF-1 stability, was decreased in WRN-depleted cells. Interestingly, expression levels of GLUT1, a known dehydroascorbic acid transporter, were also decreased in WRN-depleted cells. Ascorbate supplementation of WRN-depleted cells led to a dose-dependent inhibition of HIF-1 activation. These results indicate that WRN protein regulates HIF-1 activation by affecting mitochondrial ROS production and intracellular ascorbate levels. This work provides a novel mechanistic link between HIF-1 activity and different age-associated pathologies. PMID:22659133

Photosynthesis provides a strong reducing power and a high risk for generation of reactive oxygen species (ROS) particularly under chilling stress. Ascorbate peroxidases (APXs) reduce H(2)O(2) to water and play an important role in the antioxidant system of plants. Though thylakoid ascorbate peroxidase (tAPX) has been thought to be key regulator of intracellular levels of H(2)O(2), its physiological significance in the response to chilling stress is still under discussion. To study the contribution of tAPX to the ROS scavenging, a tomato thylakoidal ascorbate peroxidase gene (LetAPX) was isolated and transgenic tomatoes were obtained. The LetAPX-GFP fusion protein was targeted to chloroplast in Arabidopsis mesophyll protoplast. RNA blotting analysis revealed that the LetAPX transcript expression was up-regulated by chilling, high light, exogenous salicylic acid (SA) and methyl viologen (MV). Over expression of LetAPX in tomatoes conferred tolerance to chilling stress by maintaining higher reduced glutathione (GSH) content, chlorophyll and APX activities compared with wild type (WT) plants. Furthermore, transgenic plants showed lower levels of hydrogen peroxide (H(2)O(2)) and ion leakage, lower malendialdehyde (MDA) content, higher net photosynthetic rate (Pn) and higher maximal photochemical efficiency of PSII (Fv/Fm). The oxidizable P700 decreased more obviously in WT than that in transgenic plants under chilling stress in low irradiance. The results suggested that over expression of tAPX played a key role both in alleviating photo inhibition of PSI and PSII and enhancing their tolerance to chilling stress. PMID:22475501

The kinetics of the reduction of ferric chelate by ascorbic acid have been determined at a typical flue-gas scrubber-system operating temperature ({approximately}55{degrees}C). The ascorbic acid reaction has the same reduction rate expression as the reduction by bisulfite ions, namely, first order with respect to the concentrations of both Fe(III)*EDTA and monoionic species of ascorbic acid. The reaction rate isnegative first order with respect to Fe(II)*EDTA concentration. In the pH range of 6--8, reduction of the hydrolyzed form of the metal chelate compound was negligible. The rate constant for the ascorbic acid reduction reaction is almost 400 times larger than that for the bisulfite reduction reaction under the same reaction conditions. There was no contribution associated with the nonionized form of ascorbic acid.

Abstract The term -vitamin- is used to define a number of organic compounds that have to be obtained from different foods because the organism itself cannot synthesize them in the quantities needed to sustain life. Vitamin C is the common name for L-ascorbic acid. In humans, the principal role of this molecule is to scavenge reactive oxygen species, due to its antioxidant capacity, and to serve as cofactor for many enzymes. A deficiency of L-ascorbic acid is traditionally linked to human diseases such as scurvy. Plant foods are the principal source of L-ascorbic acid for humans. There is a high variability of L-ascorbic acid content in the various plant organs that are used for human consumption. This diversity is related to the specific functions played by L-ascorbic acid in the different...

Formation of OH radicals in the stomach is possible by Fenton-type reactions, as gastric juice contains ascorbic acid (AA), iron ions and H2O2. An objective of the present study is to elucidate the effects of salivary SCN- and NO2- on the hydroxylation of salicylic acid which was induced by H2O2/Fe(II) and AA/H2O2/Fe(II) systems. Thiocyanate ion inhibited the hydroxylation of salicylic acid by the above systems in acidic buffer solutions and in acidified saliva. The inhibition by SCN- was deduced to be due to SCN- -dependent scavenging of OH radicals. Nitrite ion could enhance the SCN- -dependent inhibition of the hydroxylation induced by AA/H2O2/Fe(II) systems. The enhancement was suggested to be due to scavenging of OH radicals by NO which was formed by the reactions among AA, HNO2 and SCN- contained in the reaction mixture. The concentrations of SCN- and NO2-, which were effective for the inhibition, were in ranges of their normal salivary concentrations. These results suggest that salivary SCN- can cooperate with NO2- to protect stomach from OH radicals formed by AA/H2O2/Fe(II) systems under acidic conditions. PMID:15535976

A chemical protector, eysteaniine (l00 mg/kg intraperitoneally), inhibits the second irreversible drop in cholesterol and ascorbic acid which, in the controls, begins on the second day after a total-body expesure of rats to 800 r of x rays (250 kv). Morphine (20 mg/kg) preceded by Nembutal (20 mg/kg) is known to inhibit the hypothalamo-pituitary-adrenal response to stress. This pharmacological treatment prior to total-body irradiation prevents any change in ascorbic acid and cholesterol values in the rat's suprarenal during the first 24 hours after irradiation, but it does not decrease the mortality, and does not change the profound depression of these two values at the third day after irradiation, even if a morphine injection (40 mg/kg) is given daily. lt is suggested that the first reversible reaction (during the 24 hours after irradiation) is a simple reaction to the physical stimulus of irradiation acting as a stress. The signilicance of the second reaction is not so clear because it happens at the third or fourth day when the general condition of the irradiated rat deteriorates. (auth)

Titanium and silicon-titanium xerogels have been obtained and it has been demonstrated that titanium(IV) incorporated into the xerogel matrix can participate in complexation reactions with ascorbic, gallic, ferulic, and caffeic acids and also rutin, quercetin, and dihydroquercetin present in aqueous solutions. In the case of dihydroquercetin 1 min of contact has been sufficient for achieving the equilibrium; the other compounds required 7?10 min. The stability constants of titanium(IV) complexes incorporated into xerogels reduced in the order dihydroquercetin > gallic acid > ascorbic acid > quercetin > caffeic acid > rutin. The procedures have been developed for solid-phase spectrophotometric determination of ascorbic, gallic, ferulic, caffeic acid as well as rutin, quercetin, and dihydroq...

Our previous work showed that gold nanoparticles could trigger chemiluminescence (CL) between luminol and AgNO3. In the present work, the effect of some biologically important reductive compounds, including monoamine neurotransmitters and their metabolites, reductive amino acids, ascorbic acid, uric acid, and glutathione, on the novel CL reaction were investigated for analytical purpose. It was found that all of them could inhibit the CL from the luminol-AgNO3-Au colloid system. Among them, monoamine neurotransmitters and their metabolites exhibited strong inhibition effect. Taking dopamine as a model compound, the CL mechanism was studied by measuring absorption spectra during the CL reaction and the reaction kinetics via stopped-flow technique. The CL inhibition mechanism is proposed to be due to that these tested compounds competed with luminol for AgNO3 to inhibit the formation of luminol radicals and to accelerate deposition of Ag atoms on surface of gold nanoparticles, leading to a decrease in CL intensity. Based on the inhibited CL, a novel method for simultaneous determination of monoamine neurotransmitters and their metabolites was developed by coupling high-performance liquid chromatography with this CL reaction. The new method was successfully applied to determine the compounds in a mouse brain microdialysate. Compared with the reported HPLC-CL methods, the proposed method is simple, fast, and could determine more analytes. Moreover, the limits of linear ranges for NE, E, and DA using the proposed method were one order of magnitude lower than the luminol system without gold nanoparticles. PMID:19481630

The juice of whole fruits of Sicilian cultivars of prickly pear (Opuntia ficus indica (L.) Mill.) was investigated, and the contents of ascorbic acid, total polyphenols, and flavonoids were determined. In the juice, ferulic acid was the chief derivative of hydroxycinnamic acid and the mean concentration of total phenolic compounds was 746 microg/mL. The flavonoid fraction, analyzed by high-performance liquid chromatography-diode array detection, consisted of rutin and isorhamnetin derivatives. The juice showed antioxidant activity in the DPPH(*) test, probably due to the phenolic compounds that are effective radical scavengers. The preventive administration of the juice inhibited the ulcerogenic activity of ethanol in rat. Light microscopy observations showed an increase in mucus production and the restoration of the normal mucosal architecture. The juice is nutritionally interesting, and its dietary intake could provide protection against oxidative damage. PMID:12903943

A methanol extract of dried leaves of Melanthera scandens was examined for antioxidant activities using a variety of assays, including 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, ferrous chelating, and ferric thiocyanate methods with ascorbic acid and EDTA as positive controls. The extract showed noticeable activities in most of these in vitro tests. The amount of phenolic compounds in the extract expressed in gallic acid equivalent was found to be 52.8 mg/g. The extract demonstrated inhibition of linoleic acid lipid peroxidation, active reducing power, and DPPH radical scavenging activities which were less than that of the positive controls. The extract also showed weaker iron chelating effect when compared with the EDTA positive control. The present results sho...

A simple, sensitive, and reliable method based on a multi-walled carbon nanotubes (MWNTs) modified carbon ionic liquid electrode (CILE) has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The acid-treated MWNTs with carboxylic acid functional groups could promote the electron-transfer reaction of DA and inhibit the voltammetric response of AA. Due to the good performance of the ionic liquid, the electrochemical response of DA on the MWNTs/CILE was better than that of other MWNTs modified electrodes. Under the optimum conditions a linear calibration plot was obtained in the range 5.0x10^-^8 to 2.0x10^-^4molL^-^1 and the detection limit was 1.0x10^-^8molL^-^1.

An optical antigenotoxicity assay using genetically engineered red fluorescent bacteria is presented. Exposure of Escherichia coli RS4U to genotoxicants [mitomycin C (MMC), nalidixic acid (NA) and hydrogen peroxide (HP)] resulted in phenotypic red fluorescence proportional to the concentration of the inducer. Except for tannic acid (TA), co-treatment of the genotoxicant-activated bacteria with ascorbic acid (AA) and aqueous plant extracts (Mangifera indica, Psidium guajava and Syzygium cumini) afforded protection against all three genotoxicants. TA was effective in suppressing the genotoxic effect of MMC and HP. The antigenotoxic effect is seen as inhibition of the genotoxicant-triggered red fluorescence. The IC50 of the plant extracts and AA varied with the genotoxicant used. Rec assay verified the antigenotoxic activity of the plant extracts. Folin-Ciocalteu test, FeCl3 test and DPPH assay confirmed the presence of polyphenolic compounds and hydrolyzable tannins in the plant extracts and the antioxidant capacity of the plant samples. PMID:16321516

... and has "definitely no side effects" Other red flags include claims about limited availability, offers of "no- ... and pain. C (ascorbic acid): Upset stomach, kidney stones, increased iron absorption. Folic Acid (folate): High levels ...

A method of estimating the iron content of solutions containing haemoglobin, ferritin, or ferrioxamine is described. Iron is released by treatment with acid permanganate and ascorbic acid before conventional determination by an Auto Analyzer technique.

Tissues are exposed to exogenous and endogenous nitrogen dioxide ((·)NO(2)), which is the terminal agent in protein tyrosine nitration. Besides iron chelation, the hydroxamic acid (HA) desferrioxamine (DFO) shows multiple functionalities including nitration inhibition. To investigate mechanisms whereby DFO affects 3-nitrotyrosine (3-NT) formation, we utilized gas-phase (·)NO(2) exposures, to limit introduction of other reactive species, and a lung surface model wherein red cell membranes (RCM) were immobilized under a defined aqueous film. When RCM were exposed to ()NO(2) covered by +/- DFO: (i) DFO inhibited 3-NT formation more effectively than other HA and non-HA chelators; (ii) 3-NT inhibition occurred at very low[DFO] for prolonged times; and (iii) 3-NT formation was iron independent but inhibition required DFO present. DFO poorly reacted with (·)NO(2) compared to ascorbate, assessed via (·)NO(2) reactive absorption and aqueous-phase oxidation rates, yet limited 3-NT formation at far lower concentrations. DFO also inhibited nitration under aqueous bulk-phase conditions, and inhibited 3-NT generated by active myeloperoxidase "bound" to RCM. Per the above and kinetic analyses suggesting preferential DFO versus (·)NO(2) reaction within membranes, we conclude that DFO inhibits 3-NT formation predominantly by facile repair of the tyrosyl radical intermediate, which prevents (·)NO(2) addition, and thus nitration, and potentially influences biochemical functionalities. PMID:22705369

Ascorbate levels decrease in organisms subjected to oxidative stress, but the responsible reactions have not been identified. Our earlier studies have shown that protein C-centered radicals react rapidly with ascorbate. In aerobes, these radicals can react with oxygen to form peroxyl radicals. To estimate the relative probabilities of the reactions of ascorbate with protein C- and O-centered radicals, we measured by pulse radiolysis the rate constants of the reactions of C-centered radicals in Gly, Ala, and Pro with O2 and of the resultant peroxyl radicals with ascorbate. Calculations based on the concentrations of ascorbate and oxygen in human tissues show that the relative probabilities of reactions of the C-centered amino acid radicals with O2 and ascorbate vary between 1:2.6 for the pi...

Melanosis and quality changes of Pacific white shrimp (Litopenaeus vannamei) treated with 0.1% green tea extract (GTE) in combination with ascorbic acid (AA) at different levels (0%, 0.005%, and 0.01%) were monitored during iced storage of 12 days. Based on in vitro study, 0.1% GTE inhibited polyphenoloxidase (PPO) from cephalothorax of Pacific white shrimp by 60.2%. Nevertheless, 0.1% GTE in combination with 0.01% AA exhibited the greater PPO inhibitory activity (93.0%) (P???2S- producing bacteria and enterobacteriaceae were retarded to a higher extent, in comparison with the control and those treated with 1.25% sodium metabisulfite (SMS; P???P???P???inhibition as well as r...

Isolation of a broth extract of the endophytic fungus Corynespora cassiicola L36 afforded three compounds, corynesidones A (1) and B (3), and corynether A (5), together with a known diaryl ether 7. Compounds 1, 3, 5, and 7 were relatively non-toxic against cancer cells, and inactive toward normal cell line, MRC-5. Corynesidone B (3) exhibited potent radical scavenging activity in the DPPH assay, whose activity was comparable to ascorbic acid. Based on the ORAC assay, compounds 1, 3, 5, and 7 showed potent antioxidant activity. However, the isolated natural substances and their methylated derivatives (1-8) neither inhibited superoxide anion radical formation in the XXO assay nor suppressed TPA-induced superoxide anion generation in HL-60 cell line. Corynesidone A (1) inhibited aromatase act...

Xylan is one of most abundant polymer after cellulose. However, its potential has yet to be completely recognized. Corn cobs contain a considerable reservoir of xylan. The aim of this work was to study some of the biological activities of xylan obtained from corn cobs after alkaline extraction enhanced by ultrasonication. Physical chemistry and infrared analyses showed 130 kDa heteroxylan containing mainly xylose:arabinose: galactose:glucose (5.0:1.5:2.0:1.2). Xylan obtained exhibited total antioxidant activity corresponding to 48.5 mg of ascorbic acid equivalent/g of xylan. Furthermore, xylan displayed high ferric chelating activity (70%) at 2 mg/mL. Xylan also showed anticoagulant activity in aPTT test. In antimicrobial assay, the polysaccharide significantly inhibited bacterial growth of Klebsiella pneumoniae. In a test with normal and tumor human cells, after 72 h, only HeLa tumor cell proliferation was inhibited (p antioxidant, anticoagulant, antimicrobial and antiproliferative compounds. PMID:805808

Based on epidemiological studies, chromium(VI) compounds are considered as more toxic and carcinogenic than chromium(III) compounds. The deleterious effects of chromium(VI) compounds are diversified affecting almost all the organ systems in a wide variety of animals. The present study, describes the cytotoxic effects of chromium trioxide, a well-known chromium(VI) compound in three tissues (liver, kidney, lungs) of male Swiss mice during post-treatment phase (5th-8th week after treatment). Lipid peroxidation, an index of oxidative stress, was determined as thiobarbituric acid-reactive substances (TBA-Rs) in mice tissues dosed with a single intraperitoneal injection of chromium trioxide (1mg/kg body weight). Tissue specific and statistically significant increases in TBA-Rs was observed in chromium-treated mice groups compared to controls in all the weeks of post-treatment. Endogenous ascorbic acid (vit-C) content of tissues which happens to be one of the stable antioxidants, declined significantly due to chromium-induction. Activity of antioxidative enzymes like superoxide dismutase (SOD), catalase (CT) and peroxidase (PD) was significantly inhibited among chromium-injected mice groups compared to respective controls. Protective role of ascorbic acid and the antioxidative enzymes in chromium-induced cytotoxicity in mice is discussed. PMID:21782722

1 The relationship between mechanical fragility, glutathione peroxidase inhibition and Heinz body formation, in erythrocytes exposed to oxidant drugs in vitro, has been investigated. All drugs tested caused Heinz body formation, and with the exception of acetyl salicylic acid and salicylic acid, also caused increased erythrocyte mechanical fragility. 2 There was a direct relationship between mechanical fragility and drug concentration. Mechanical fragility increased in parallel with Heinz body formation, with primaquine, gentisic acid, ascorbic acid and potassium chlorate. In contrast Heinz body formation occurred at drug concentrations which did not cause a marked increase in mechanical fragility in the case of menadione, acetyl phenylhydrazine and phenylhydrazine. 3 The degree of inhibition of glutathione peroxidase was directly related to increased mechanical fragility with menadione, gentisic acid and potassium chlorate. However other substances causing increased mechanical fragility resulted in little or no loss of glutathione peroxidase activity. 4 The results show that there is no constant relationship between mechanical fragility caused by drugs, the formation of Heinz bodies and the inhibition of glutathione peroxidase. The factors contributing to oxidant drug-induced haemolysis appear to be variable and depend upon the drug concerned. PMID:22454946

Study on NO2 absorption aimed at seeking a better NO2 absorption chemical at pH 4.5~7.0 for application to existing wet flue gas desulfurization (FGD). The results from the double-stirred reactor indicated that ascorbic acid has very high absorption rate at this pH range. The rate constant of ascorb...

The discovery of Helicobacter pylori as the cause of gastritis and peptic ulcers ushered in the modern era of research into gastritis and into acid-peptic diseases and rekindled interest in the role of ascorbic acid in the pathophysiology and treatment of gastritis and peptic ulcer disease. Here, we review historic and modern studies on ascorbic acid and gastric diseases with an emphasis on H. pylori gastritis and its sequelae. The relationship of ascorbic acid and gastritis and peptic ulcer and its complications was extensively studied during the 1930s through the 1950s. Much of this extensive literature has been effectively "lost." Ascorbic acid deficiency was associated with all forms of gastritis (e.g., autoimmune, chemical, and infectious) due in varying degrees to insufficient intake, increased metabolic requirements, and destruction within the GI tract. Importantly, gastritis-associated abnormalities in gastric ascorbic acid metabolism are reversed by H. pylori-eradication and potentially worsened by proton pump inhibitor therapy. Diets rich in naturally occurring ascorbic acid are associated with protection of the gastric corpus from atrophy and a reduction in the incidence of gastric cancer possibly through the ability of ascorbic acid to reduce oxidative damage to the gastric mucosa by scavenging carcinogenic N-nitroso compounds and free radicals and attenuating the H. pylori-induced inflammatory cascade. Ascorbic acid supplementation was possibly associated with a decreased incidence of bleeding from peptic ulcer disease. Pharmacologic doses of ascorbic acid also may improve the effectiveness of H. pylori-eradication therapy. Occasionally, looking back can help plot the way forward. PMID:22543844

Angiotensin II (Ang II) induces vascular smooth muscle cell (VSMC) hypertrophy, which results in several cardiovascular diseases. Ang II-induced cellular events have been mediated, in part, by reactive oxygen species (ROS) which also involve activation of mitogen-activated protein (MAP) kinases. Although it has been proposed that the therapeutic administration of antioxidants is useful for vascular diseases, the precise mechanisms which regulate ROS-sensitive signaling events have not been well characterized. Thus, we hypothesized that antioxidants may affect ROS-mediated MAP kinases activation induced by Ang II. The present findings showed that Ang II stimulated rapid and significant activation of ERK 1/2, JNK and p38 MAPK in cultured rat aortic smooth muscle cells (RASMC). Ang II-induced ERK 1/2 activation was not affected by all antioxidants examined, whereas JNK was sensitive to all antioxidants. In contrast, p38 MAPK activation was inhibited by DPI and ascorbic acid concentration-dependently, but by NAC only at high concentration. DETC and Trolox C had no effects on p38 MAPK activation by Ang II. We further examined the effects of antioxidants on Ang II-induced increases in oxygen consumption as an index of ROS generation in RASMC. DPI strongly inhibited Ang II-induced increases in oxygen consumption. DETC also inhibited Ang II-induced oxygen consumption, whereas ascorbic acid markedly augmented it. These findings suggest that the inhibitory effects of antioxidants on MAP kinases activation in VSMC are attributable, in part, to their modulating effects on ROS generation by Ang II in VSMC. Thus, inhibition of MAP kinases by antioxidants may imply their usefulness for relief of cardiovascular diseases. (Hypertens Res 2001; 24: 251-261)   

The effects of a large ascorbic acid dose on cytochrome P4501A1 gene expression induced by cigarette smoke exposure was studied in Osteogenic Disorder Shionogi rats, which lack ascorbic acid biosynthesis. The rats were divided into four groups and were administered either a minimal amount (4 mg/day, 4S and 4C) or a large amount (40 mg/day, 40S and 40C) of ascorbic acid. The 4S group and 40S group were daily exposed to cigarette smoke for 2 hours, while the 4C group and 40C group were not. At the end of the 25-day experiment, the rats were killed. The cytochrome P4501A1 mRNA level both in the liver and lung was measured by a competitive reverse transcription—polymerase chain reaction method. When a minimal amount of ascorbic acid was administered, the cytochrome P4501A1 mRNA increased in the liver of the cigarette smoke-exposed group (4S) compared with the control group (4C). On the other hand, when a large amount of ascorbic acid was administered, this increase was no observed in the cigarette smoke-induced group (40S) in liver. On the other hand, in lung, an increased mRNA level in 4S group was not decreased by large ascorbic acid administration (40S). This is the first direct mRNA-level evidence of the effects of a large ascorbic acid dose on the gene expression stimulated by cigarette smoke.   

Health benefits including antioxidant potential of black tea (Camellia sinensis), lemon (Citrus limon) and honey bees (Apis mellifera) have been extensively reported. Nevertheless, nothing is reported about the effects of their concomitant use. Herein, those effects were evaluated in infusions of lemon-flavoured black tea with three different kinds of honey (light amber, amber and dark amber) from Lavandula stoechas, Erica sp. pl. and other indigenous floral species from north-east Portugal, a region with high amounts of this food product. Data obtained showed that the use of honey (dark amber>amber>light amber) potentiates the antioxidant activity of lemon-flavoured black tea, increasing the reducing power and lipid peroxidation inhibition properties, as also the antioxidant contents such as phenolics, flavonoids and organic acids including ascorbic acid. PMID:22856394

The Opuntia ficus indica f. inermis methanolic flowers extract (OMFE) was phytochemical studied, in vitro tested for their potential antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power, linoleic acid peroxidation assays and in vivo evaluated for its ability to prevent ethanol-induced gastric ulcer in rats. The OMFE was rich in polysaccharide, phenolics and flavonoids contents and exhibited a moderate in vitro antioxidant activity when compared with (+)-catechin and ascorbic acid. Pre-treatment with OMFE at oral doses 250, 500 and 1000 mg/kg body weight was found to provide a dose-dependent protection against ethanol-induced gastric ulcer by averting the deep necrotic lesions of the gastric epithelium, by preserving normal antioxidant enzymes activities, by inhibiting the lipid peroxidation, the oxidation of protein and the DNA fragmentation in gastric mucosa. The antiulcerogenic activity of OMFE might be due to a possible synergistic antioxidant and antihistaminic-like effects. PMID:22004960

Salicylic acid (SA) is required for plant systemic acquired resistance (SAR) to viruses. However, SA-deficient plants adapt to RNA virus infections better, which show a lighter symptom and have less reactive oxygen species (ROS) accumulation. The virus replication levels are higher in the SA-deficient plants during the first 10 days, but lower than the wild-type seedlings after 20 dpi. The higher level of glutathione and ascorbic acid (AsA) in SA-deficient plants may contribute to their alleviated symptoms. Solo virus-control method for mortal viruses results in necrosis and chlorosis, no matter what level of virus RNAs would accumulate. Contrastingly, early and high-dose AsA treatment alleviates the symptom, and eventually inhibits virus replication after 20 days. ROS eliminators could...

Amorphous silica gel modified carbon paste electrode (CPE) offers substantial improvements in voltammetric sensitivity and selectivity towards determination of dopamine (DA). Cyclic voltammetry of Fe(CN)6^3^-^/^4^- as a negatively charged probe revealed that the surface of the silica gel modified carbon paste electrode had a high density of negative charge at pH 8.0. Therefore, the modified electrode adsorbed DA (pKa=8.9) and enhanced its voltammetric response while repulsed ascorbic acid (AA) (pKa=4.2) and uric acid (UA) (pKa=5.4) and inhibited their interfering effects. The influence of various experimental parameters including percent of silica gel in the CPE, pH of solution, and accumulation time and potentials, on the voltammetric response of DA was investigated. At the optimum condit...

The effects of Fe2+ on the trimethylamine N-oxide (TMAO) demethylating activity of the Harpadon nehereus kidney extract were studied in this research. The activity of the kidney extract was presumably inhibited by ethylene diamine tetra-acetic acid (EDTA), which indicates that the kidney extract contains an enzyme or enzyme system with metal cations as activator. Activity of the kidney extract was enhanced significantly when Fe2+ was added into the model system in vitro. As the concentration of Fe2+ increased, the decomposing rate of TMAO increased rapidly until TMAO decomposed completely. The activity of the kidney extract was also enhanced by reductant such as ascorbic acid. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) was employed to determine the content of total i...

Intermediate moisture products made from blanched apple flesh and green tea extract (about 6mg of monomeric flavan 3-ols added per g of dry apple) or blanched apple flesh (control) were produced, and their quality attributes were investigated over storage for two months at water activity (aw) levels of 0.55 and 0.75, at 30degreeC. Products were evaluated for colour (L*, a*, and b* Hunter's parameters), phytochemical contents (flavan 3-ols, chlorogenic acid, dihydrochalcones, ascorbic acid and total polyphenols), ferric reducing antioxidant potential, 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl radical-scavenging activity and ability to inhibit formation of fructose-induced advanced glycation end-products. During storage of the fortified and unfortified intermediate moisture apples, water...

ABSTRACT: There are few available compounds that can both control browning and enhance microbial safety of fresh-cut fruits. In the present study, the antibrowning ability of sodium acid sulfate (SAS) on "Granny Smith" apple slices was first investigated in terms of optimum concentration and treatment time. In a separate experiment, the apple slices were treated with water or 3% of SAS, calcium ascorbate, citric acid, or acidified calcium sulfate for 5 min. Total plate count, color, firmness, and tissue damage were assessed during a 21-d storage at 4 degreeC. Results showed that the efficacy of SAS in inhibiting browning of apple slices increased with increasing concentration. A minimum 3% of SAS was needed to achieve 14 d of shelf life. Firmness was not significantly affected by SAS at 3%...

I.v. ascorbic acid has been used in an effort to mobilize ferritin stores in hyporesponsive HD patients receiving Epoetin alfa. However, not all patients who respond to i.v. ascorbic acid therapy will have subsequent decline in feritin stores (Gastaldello et al., 1995; Tarng & Huang, 1998). Additionally, predicting those patients who will overcome their Epoetin alfa hyporesponsiveness remains unclear. Ascorbic acid's effect on hemosiderin deposits may be another possible mechanism to the increased Epoetin alfa response observed in some HD patients (Hemosiderin is a pathologic deposition of iron in tissues including the spleen, small intestine, and bone marrow). Although there are no well-controlled studies evaluating hemosiderin and i.v. ascorbic acid, it should be noted that subjects with scurvy often present with excessive iron deposits in the tissues, indicating the possible effects of ascorbic acid on hemosiderin metabolism (Bothwell et al., 1964). Ascorbic acid deficiency is often present in many HD patients due to its removal during dialysis and lack of dietary intake (Ponka & Kuhlback, 1983). It remains controversial whether oral ascorbic acid supplementation is indicated in patients receiving HD. Therefore, the Recommended Daily Allowance (RDA) of 60 mg/day should be advised (Makoff, 1999). I.v. ascorbic acid should be considered as a possible adjuvant to therapy in patients who are "iron-overloaded" and hyporesponsive to Epoetin alfa. Although the long-term effects of i.v. ascorbic acid on HD patients is unknown, the potential risk of secondary oxalosis should be considered (Costello, 1991; Pru, Eaton, & Kjellstrand, 1985). It may be necessary to monitor plasma oxalate levels if long-term therapy with i.v. ascorbic acid is used. Clinical studies have examined i.v. ascorbic acid doses from 300 mg-500 mg given up to TIW for a maximum duration of 12 weeks without any significant deleterious effects (Gastaldello et al., 1995; Tarng & Huang, 1998; Tarng et al., 1999). However, large-scale, prospective, and controlled trails are needed to determine the long-term safety and efficacy of i.v. ascorbic acid therapy in iron overloaded HD patients receiving Epoetin alfa. PMID:11276634

In this study, we examined changes in radical-scavenging activity, as well as in ascorbic acid content, total phenol content and color, in 6 kinds of shredded vegetables during storage. Radical-scavenging activity, ascorbic acid content and total phenol content of red cabbage were initially higher than those of the other vegetables. In shredded vegetables stored at 10°C for 7 days under air or under nitrogen gas, radical-scavenging activity remained unchanged, but ascorbic acid in green pepper decreased in the first day and remained unchanged thereafter. Total phenolics also remained relatively constant in shredded vegetables during storage.   

A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance.   

Experiments were performed to investigate the effect of ascorbic acid in reducing haemato-biochemical changes in pack donkeys during the cold-dry (harmattan) season. Six experimental donkeys administered orally with ascorbic acid (200 mg/kg), and six control donkeys, not administered with ascorbic acid, were subjected to packing. Blood samples were collected from all donkeys for haematological and biochemical analyses. In the control donkeys, packed cell volume (PCV), erythrocyte count and haemoglobin concentration (Hb) decreased significantly (Phaematological parameters, ameliorated by AA administration. AA may modulate neutrophilia and induce a considerable alteration of erythroid markers in donkeys subjected to packing during the harmattan season. PMID:23154452

To observe lipid peroxidation of additive-free submitochondrial particles, we incubated submitochondrial particles in the absence of exogenous irons and t-butyl hydroperoxide. After the incubation, the phospholipids were hydrolyzed by phopholipase A2, and the fatty acid constituents were analyzed by high-performance liquid chromatography, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry. Contrary to a commonly accepted theory, lipid peroxidation in the submitochondrial particles did not need the addition of NADH. In the phospholipid constituent fatty acids of the oxidized submitochondrial particles, derivatives of hydroperoxides of linoleic acid such as keto, hydroxy, trihydroxy, and hydroxyepoxy compounds were generated. Lipid peroxidation in the submitochondrial particles was not inhibited by the addition of catalase, superoxide dismutase, hydroxyl radical scavengers, or ethylenediaminetetraacetic acid, but was inhibited by the addition of KCN, antimycin-A, NADH, ubiquinol, deferoxamine mesylate, ascorbic acid, and alpha-tocopherol. The cardiolipin-cytochrome c lipid peroxidation system could mimic the lipid peroxidation of the submitochondrial particles, in terms of linoleic acid products and the inhibitory patterns of radical scavengers and electron transfer chain inhibitors. Thus, lipid peroxidation in the submitochondrial particles seems to be due to phospholipid-hemoprotein lipid peroxidation systems such as the cardiolipin-cytochrome c system. PMID:9641268

Hydroxyl radicals (OH) generated in the human body may play an important role in tissue injury at sites of inflammation in oxidative stress-originated diseases. As a more convenient, efficient, and less costly alternative to HPLC/electrochemical detection techniques and to the nonspecific, low-yield deoxyribose (TBARS) test, we used a salicylate probe for detecting OH generated by the reaction of iron(II)-EDTA complex with H(2)O(2). The produced hydroxyl radicals attack both the salicylate probe and the hydroxyl radical scavengers that are incubated in solution for 10 min. Added radical scavengers compete with salicylate for the OH produced, and diminish chromophore formation from Cu(II)-neocuproine. At the end of the incubation period, the reaction was stopped by adding catalase. With the aid of this reaction, a kinetic approach was adopted to assess the hydroxyl radical scavenging properties of polyphenolics, flavonoids and other compounds (e.g., ascorbic acid, glucose, mannitol). A second-order rate constant for the reaction of the scavenger with OH could be deduced from the inhibition of colour formation due to the salicylate probe. In addition to phenolics and flavonoids, five kinds of herbs were evaluated for their OH scavenging activity using the developed method. The modified CUPRAC (cupric ion reducing antioxidant capacity) assay proved to be efficient for ascorbic acid, gallic acid and chlorogenic acid, for which the deoxyribose assay test is basically nonresponsive. An important contribution of this developed assay is the inhibition of the Fenton reaction with catalase degradation of hydrogen peroxide so that the remaining H(2)O(2) would neither give a CUPRAC absorbance nor involve in redox cycling of phenolic antioxidants, enabling the rapid assay of polyphenolics. PMID:18482604

Mycoplasma hyorhinis (M. hyorhinis) infection leads cultured cells to various biological alterations in cell metabolism including apoptosis. Apoptosis induced by M. hyorhinis has mainly been considered to be due to mycoplasmal endonucleases. We previously reported that apoptosis in a human carcinoma cell line AZ-521 infected with M. hyorhinis was enhanced by addition of L-ascorbic acid to cell cultures. Since both L-ascorbic acid addition and M. hyorhinis infection activated cellular iNOS, we examined the hypothesis that nitric oxide (NO) exerts an apoptotic effect on M. hyorhinis-infected cells and down-regulates E-cadherin. In this study, we showed that M. hyorhinis infection activates iNOS mRNA synthesis, NO production, and caspase-3 activity and attenuates E-cadherin mRNA synthesis by quantitative real-time PCR, Griess assay and fluorescence caspase-3 detection. L-NAME decreased the numbers of apoptotic cells through inhibition caspase-3 activity. Our results indicate that NO causes anoikis throughout attenuation of E-cadherin and activation of caspase-3 in human gastric carcinoma cell line AZ-521 cells infected with M. hyorhinis.   

The effect of a new oral hypoglycemic agent troglitazone, (+/-)-5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl-methoxy)benz yl]-2,4-thiazolidinedione as an antioxidant against the free radical-mediated oxidation of low density lipoprotein (LDL) was studied. The oxidation of LDL gives cholesteryl ester hydroperoxide and phosphatidylcholine hydroperoxide as major primary products. Troglitazone incorporated exogenously into LDL inhibited the oxidations of LDL induced by either aqueous or lipophilic peroxyl radicals and suppressed the formation of lipid hydroperoxides efficiently. Ascorbic acid added into the aqueous phase spared both endogenous alpha-tocopherol and troglitazone in LDL. It was also found by absorption spectroscopic and electron spin resonance (ESR) studies that troglitazone reacted rapidly with a galvinoxyl radical to give a chromanoxyl radical which gives the same ESR spectrum as alpha-tocopherol. This ESR spectrum disappeared rapidly when ascorbic acid was added into the system. These results show that troglitazone acts as a potent antioxidant and protects LDL from oxidative modification. PMID:8782853

Mycoplasma hyorhinis (M. hyorhinis) infection leads cultured cells to various biological alterations in cell metabolism including apoptosis. Apoptosis induced by M. hyorhinis has mainly been considered to be due to mycoplasmal endonucleases. We previously reported that apoptosis in a human carcinoma cell line AZ-521 infected with M. hyorhinis was enhanced by addition of L-ascorbic acid to cell cultures. Since both L-ascorbic acid addition and M. hyorhinis infection activated cellular iNOS, we examined the hypothesis that nitric oxide (NO) exerts an apoptotic effect on M. hyorhinis-infected cells and down-regulates E-cadherin. In this study, we showed that M. hyorhinis infection activates iNOS mRNA synthesis, NO production, and caspase-3 activity and attenuates E-cadherin mRNA synthesis by quantitative real-time PCR, Griess assay and fluorescence caspase-3 detection. L-NAME decreased the numbers of apoptotic cells through inhibition caspase-3 activity. Our results indicate that NO causes anoikis throughout attenuation of E-cadherin and activation of caspase-3 in human gastric carcinoma cell line AZ-521 cells infected with M. hyorhinis. PMID:20179380

Neohesperidin dihydrochalcone (NHDC), a non-nutritive sweetening agent, is simply produced by hydrogenation of neohesperidin. The aim of this study is to evaluate the antioxidant and radical scavenging properties of neohesperidin dihydrochalcone and other structurally related compounds (phloridzin, neohesperidin) toward different reactive radical and oxygen species including ·ABTS+, ·O2?, ·OH, H2O2, and HOCl in vitro. NHDC showed remarkable radical scavenging activity against stable radical and reactive oxygen species (ROS) in concentration dependent manner. Especially, NHDC was the most potent inhibitor of H2O2 and HOCl. NHDC showed HOCl scavenging activity of 93.5% and H2O2 scavenging property of 73.5% which was more than those of all the tested compounds including ascorbic acid and BHT. Moreover, NHDC could inhibit protein degradation, plasmid DNA strand cleavage and HIT-T15, HUVEC cell death from HOCl attack while mannitol, BHT, and ascorbic acid could not protect them effectively. These results suggest that NHDC is a potent antioxidant, especially it is evaluated as a novel HOCl scavenger. This study implies the possibility of therapeutic effect of NHDC on ROS-related inflammatory diseases.   

Fresh-cut carambola (Averrhoa carambola L.) has limited marketability due to cut-surface browning. The effect of chemical treatments (ascorbic acid, citric acid and Ca-EDTA), controlled atmosphere (0.4-20.3% O2) and the association of these processes was investigated. Post-cutting dip and low-oxygen atmospheres did not prevent discoloration or improve sensory and physicochemical parameters. However, ascorbic acid (0.5% and 1%) dips reduced polyphenol oxidase (PPO) activity during storage at 4.5degreeC, with 1% ascorbic acid inducing the lowest activity. Although cut-surface browning of `Maha' slices was not relevant, carambola slices treated with 1% ascorbic acid in association with 0.4% oxygen did not present significant browning or loss of visual quality for up to 12 days, 3 days longer ...

The influence of polyphenol oxidase and ascorbate oxidase on radical-scavenging activity and contents of total phenol, chlorogenic acid, and ascorbic acid in vegetables during the cooking process were investigated. In the case of burdock and lettuce, which have a high activity of polyphenol oxidase, the radical-scavenging activity and the content of total phenol and chlorogenic acid decreased drastically within 1 min. In the case of broccoli, however, only a small decrease of radical-scavenging activity was observed, and total phenol and chlorogenic acid decreased almost not at all. The decrease of the activity in broccoli depended on the oxidation of ascorbic acid by ascorbate oxidase. None of these compounds decreased after the enzymes had been inactivated by heating.   

Leaf senescence induced by 2,4-dichlorophenoxyacetic acid (2,4-D) and senescence inhibition caused by supplementation with silver (Ag(+)) ions in the form of silver nitrate (AgNO(3)) or silver nanoparticles (AgNPs) were investigated in 8-day-old mung bean (Vigna radiata L. Wilczek) seedlings. Inhibition of root and shoot elongation were observed in mung bean seedlings treated with 500?M 2,4-D. Concomitantly, the activity of 1-aminocyclopropane-1-carboxylic acid synthase was significantly induced in leaf tissue. Leaf senescence induced by 2,4-D was closely associated with lipid peroxidation as well as increased levels of cytotoxic hydrogen peroxide (H(2)O(2)) and superoxide radicals (O(2)(·-)). Despite decreased catalase activity, the activities of peroxidase, superoxide dismutase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase were increased during 2,4-D-induced leaf senescence. Further, the levels of reduced ascorbate, oxidized ascorbate, and reduced glutathione were markedly decreased, whereas the level of oxidized glutathione increased. 2,4-D-induced leaf senescence in mung bean was accompanied by an increase in positive terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, nuclear DNA fragmentation, and the activity of a 15-kDa Ca(2+)-dependent DNase. Supplementation with 100?M AgNO(3) or AgNPs inhibited 2,4-D-induced leaf senescence. The present results suggest that increased oxidative stress (O(2)(·-) and H(2)O(2)) led to senescence in mung bean leaves. Furthermore, significantly induced antioxidative enzymes are not sufficient to protect mung bean cells from 2,4-D-induced harmful ROS. PMID:21144762

Hypericum androsaemum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Since polyphenolic compounds have high antioxidant potential, the ability of H. androsaemum infusion to act as a scavenger of reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid) was investigated. Superoxide radical was generated by the xanthine/xanthine oxidase and phenazine methosulphate/NADH systems. The infusion-mediated prevention of nitroblue tetrazolium reduction by the superoxide radical was used as the measured endpoint. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and assayed by evaluating deoxyribose degradation using the thiobarbituric acid method. Hypochlorous acid scavenging activity was tested by measuring the inhibition of hypochlorous acid-induced 5-thio-2-nitrobenzoic acid oxidation to 5,5?-dithiobis(2-nitrobenzoic acid). The tested infusion mainly exhibited a potent scavenging effect on superoxide radicals (although a noncompetitive inhibitory effect on xanthine oxidase was also observed). The infusion also acted as a moderate scavenger of hydroxyl radicals and hypochlorous acid. A phytochemical study of the infusion was also undertaken, and nine phenolic compounds were identified.   

This work examines the involvement of haem oxygenase-1 (HO-1) in salicylic acid (SA)-induced alleviation of oxidative stress as a result of cadmium (Cd) stress in alfalfa (Medicago sativa L.) seedling roots. CdCl(2) exposure caused severe growth inhibition and Cd accumulation, which were potentiated by pre-treatment with zinc protoporphyrin (ZnPPIX), a potent HO-1 inhibitor. Pre-treatment of plants with the HO-1 inducer haemin or SA, both of which could induce MsHO1 gene expression, significantly reduced the inhibition of growth and Cd accumulation. The alleviation effects were also evidenced by a decreased content of thiobarbituric acid-reactive substances (TBARS). The antioxidant behaviour was confirmed by histochemical staining for the detection of lipid peroxidation and the loss of plasma membrane integrity. Furthermore, haemin and SA pre-treatment modulated the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), and guaiacol peroxidase (POD), or their corresponding transcripts. Significant enhancement of the ratios of reduced/oxidized homoglutathione (hGSH), ascorbic acid (ASA)/dehydroascorbate (DHA), and NAD(P)H/NAD(P)(+), and expression of their metabolism genes was observed, consistent with a decreased reactive oxygen species (ROS) distribution in the root tips. These effects are specific for HO-1, since ZnPPIX blocked the above actions, and the aggravated effects triggered by SA plus ZnPPIX were differentially reversed when carbon monoxide (CO) or bilirubin (BR), two catalytic by-products of HO-1, was added. Together, the results suggest that HO-1 is involved in the SA-induced alleviation of Cd-triggered oxidative stress by re-establishing redox homeostasis. PMID:22915740

Ascorbic acid (AA) is one of the most important endogenous reducing agents and can participate in a variety of cellular events. In vitro, AA can act as a potent oxidant agent in the presence of free metals, promote modifications in protein structures and form reactive oxygen species during its oxidation. We have observed that AA (above 6 mmol/l) inactivates ?-aminolevulinate dehidratase (?-ALA-D), a sulfhydryl-containing enzyme and that the inhibitory action was considerably decreased when 3-morpholinepropanesulfonic acid buffer (MOPS – pH: 6.8; 100 mmol/l) was used in the ?-ALA-D activity assay instead of potassium phosphate buffer (PB – pH: 6.8; 100 mmol/l). ?-ALA-D inhibition, probably, is mediated by the oxidation of –SH groups caused by the auto-oxidation of AA promoted by metals or another oxidizing system present in liver supernatants. This hypothesis was confirmed by studying dithiothreitol (DTT – 400 ?mol/l) oxidation, as a model of enzyme thiols, where we observed that the mechanism underlying DTT and ?-ALA-D oxidation caused by ascorbate is the same. The difference observed between different buffers may be related to the oxidation of Fe(II) to Fe(III) that was more accentuated in PB than in MOPS buffer. The presence of ethilenediamintetraacetic acid (EDTA – 100 ?mol/l) and Fe(III) (5 ?mol/l) stimulated DTT oxidation more in PB than in MOPS buffer. Deferroxamine (DF – 100 ?mol/l) considerably decreased DTT oxidation. Catalase (0.4 mg/ml) and Superoxide dismutase (SOD – 300 U/ml) had only a modest effect on DTT oxidation. The present results suggest that ?-ALA-D inhibition by AA is mediated primarily by the oxidized form of AA and reactive oxygen species play only a modest role in the process.   

In pH 8.9 Tris?HCl buffer solutions, alkaline phosphatase (ALP) catalyzed the hydrolysis of ascorbic acid 2-phosphate (AAP) substrate to form ascorbic acid. Then H3PO4 was added to stop the enzymatic reaction and HAuCl4 was used to react with ascorbic acid to generate gold nanoparticles that exhibited a resonance scattering (RS) peak at 600 nm. Under the selected conditions, when the activity of ALP increased, the formed ascorbic acid and gold nanoparticles also increased. Thus, the RS intensity at 600 nm enhanced linearly. The linear range was 0.06?22 U/L, with a detection limit of 0.03 U/L. The ALP in serum was analyzed, and the results were in agreement with those of the fluorescence method.

The formation of CuCl nanoplatelets from the ionic liquid precursor (ILP) butylpyridinium tetrachlorocuprate [C(4)Py](2)[CuCl(4)] using ascorbic acid as a reducing agent was investigated. In particular, electron paramagnetic resonance (EPR) spectroscopy was used to evaluate the interaction between ascorbic acid and the Cu(II) ion before reduction to Cu(I). EPR spectroscopy suggests that the [CuCl(4)](2-) ion in the neat IL is a distorted tetrahedron, consistent with DFT calculations. Addition of ascorbic acid leads to the removal of one chloride from the [CuCl(4)](2-) anion, as shown by DFT and the loss of symmetry by EPR. DFT furthermore suggests that the most stable adduct is formed when only one hydroxyl group of the ascorbic acid coordinates to the Cu(II) ion. PMID:21617795

Cisplatin (cis-diaminedichloroplatinum-II) is a widely used antineoplastic agent in the treatment of a variety of cancers. The aim of the present study was to investigate the testicular toxicity of cisplatin in mice at human therapeutic dose-levels, and to investigate any protective effects of concomitantly administered l-ascorbic acid (i.p.; 10mg/kg). Adult male BALB/C mice (13-15-week-old) were treated (i.p.) with two cycles of 5 days each of cisplatin with 17 days of recovery period between cycles, as follows: Group I (G-I) - water (N=10); Group II (G-II) - l-ascorbic acid (N=6); Group III (G-III) - 1mg/kg (N=6); Group IV (G-IV) - 1mg/kg+l-ascorbic acid (N=6); Group V (G-V) - 2.5mg/kg (N=6); and Group VI (G-VI) - 2.5mg/kg+l-ascorbic acid (N=8). All animals were sacrificed on third day a...

A carbon-paste electrode modified with bis(4prime-(4-pyridyl)-2,2prime:6prime,2primeprime-terpyridine)iron(II) thiocyanate, [Fe(pyterpy)2](SCN)2, where pyterpy = 4prime-(4-pyridyl)-2,2prime:6prime,2primeprime-terpyridine, have been applied to the electrocatalytic oxidation of ascorbic acid which reduced the overpotential by about 200mV with obviously increase the current response. Due to its strong electrocatalytic activity towards ascorbic acid, the modified carbon-paste electrode can resolve the overlapped voltammetric waves of ascorbic acid (AA) and dopamine (DA) into two well-defined voltammetric peaks with peak-to-peak separation in potentials of about 200mV. This property allows to selective determination of ascorbic acid in the presence of dopamine. Relative standard deviations for ...

Chemiluminescence (CL) was immediately observed after an iron-chlorophyllin aqueous solution was added to an acetonitrile/water mixed solution containing hydrogen peroxide. Quenching of the iron-chlorophyllin complex CL was caused by adding L-ascorbic acid. Based on these facts, a determination method involving small amounts of L-ascorbic acid was developed. As a result, this CL system is able to determine L-ascorbic acid over a wide concentration range of 4.0 × 10-12 to 4.0 × 10-4 mol L-1. Also, coexisting substances, such as sugar and vitamins, did not interfere with the determination. Moreover, the participation to the CL was not observed when using other reducing agents, such as hydroxylamine hydrochloride. As an application for practical use, L-ascorbic acid in soft-drink powder was determined. The experimental value was almost the same as the calculated one (5.30 × 10-5 mol L-1).   

The aim of this study was to evaluate the in vitro effects of ascorbic acid on Ross-308 chicken sperm quality. The semen was collected from eight teen Ross-308 broiler breeder roosters and mixed together. The mixed semen was diluted with modified Ringer?s solution and supplemented with five treatment levels (0%, 0.5%, 1%, 2%, and 3%) of ascorbic acid (w/v). Treatments were evaluated for sperm motility, viability, and morphological defect rates at 0, 3, 6, 10, and 24?h after storage at 4?C. At 0, 3, and 6 of storage, no significant differences were observed between treatments with ascorbic acid and controls for all spermatozoa quality parameters. At 10?h, sperm viability in treatment added with 1% ascorbic acid was significantly higher than control and other treatments. In this time, there ...

method carotin by Tautsin s method ascorbic acid by titra tion with ...... dissipated Some response decline was still present 3 weeks after the ...... ments related to intercontinental flight and Forest Service flights and the ...... fumes, dust, or mist.

... the Mayo Diabetes Diet Book Question Too much vitamin C: Harmful? Is it possible to take too much vitamin C? Answer from Katherine Zeratsky, R.D., L.D. Vitamin C (ascorbic acid) is an essential nutrient. Still, ...

To prevent oxidative quality changes, a few selected antioxidants, ascorbic acid, or an ascorbic acid plus ?-tocopherol combination were electrostatically sprayed on the surface of ground beef patties. Color, metmyoglobin, oxidation-reduction potential, lipid oxidation, and volatiles of the samples were determined during the 8 d of aerobic storage. Spraying of ascorbic acid at 500 mg/kg was the most effective in controlling discoloration of ground beef. Spraying of ascorbic acid at 500 mg/kg was also effective in reducing 2-thiobarbituric acid-reactive substances and volatile aldehydes such as hexanal and heptanal related to lipid oxidation. Spraying of phenolic antioxidants such as tocopherol, sesamol, or rosemary oleoresin showed significant (P antioxidant effects, but had no effects (P antioxidant activities among the antioxidants, and its antioxidant effect was as strong as that of 500 mg/kg of ascorbic acid. It was concluded that electrostatic spray of ascorbic acid on the surface of ground beef at 500 mg/kg was an efficient and economical way to prevent both lipid oxidation and color changes in ground beef. PMID:21097682

  Glycosylated ascorbic acids were synthesized by using the transglycosylation activity of Bacillus stearothermophilus maltogenic amylase with maltotriose to show effective antioxidative activity with enhanced oxidative stability. The modified ascorbic acids comprised mono- and di-glycosyl transfer products with an ?-(1,6)-glycosidic linkage. The antioxidative effects of the glycosyl derivatives of ascorbic acid on the lipid oxidation of cooked chicken breast meat patties were compared, and the synergistic effect when combined with ?-tocopherol was determined in terms of thiobarbituric acid-reactive substances (TBARS) and volatiles production during storage. The results indicate that the glycosylated ascorbic acids had very effective antioxidative activity in preventing lipid oxidation, and were better in their synergistic effect in comparison to authentic ascorbic acid, with maltosyl-ascorbic acid being the most effective. Volatiles production was highly correlated with the TBARS values in the lipid oxidation of cooked meat. The antioxidative effect preventing the production of volatiles was particularly strong on pentanal, fairly strong on propanal and butanal, and not at all on ethanal. Propanal, pentanal, and the total volatiles thus provided a good representation of the lipid oxidation status of cooked chicken meat.   

Effects of ascorbic acid (AA), ascorbic acid glycoside (AAG) and ?-tocopherol monoglycoside (TMG) on radiation - and H2O2-induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, AAG was found to possess the most marked protector properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of AA and AAG, as well as properties of radical adducts formed during their interaction with OH radicals.   

The authors report a case of calcium oxalate arthropathy in a woman undergoing intermittent peritoneal dialysis who was not receiving pharmacologic doses of ascorbic acid. She developed acute arthritis, with calcium oxalate crystals in Heberden's and Bouchard's nodes, a phenomenon previously described in gout. Intermittent peritoneal dialysis may be less efficient than hemodialysis in clearing oxalate, and physicians should now consider calcium oxalate-associated arthritis in patients undergoing peritoneal dialysis who are not receiving large doses of ascorbic acid.

Soils and ground water in nature are dominated by chloride and sulphate salts. There have been several studies concerning NaCl salinity, however, little is known about the Na(2)SO(4) one. The effects on antioxidative activities of chloride or sodium sulphate in terms of the same Na(+) equivalents (25 mM Na(2)SO(4) and 50 mM NaCl) were studied on 30 day-old plants of Ocimum basilicum L., variety Genovese subjected to 15 and 30 days of treatment. Growth, thiobarbituric acid reactive substances (TBARS), relative ion leakage ratio (RLR), hydrogen peroxide (H(2)O(2)), ascorbate and glutathione contents as well as the activities of ascorbate peroxidase (APX, EC 1.11.1.11); glutathione reductase (GR, EC 1.6.4.2) and peroxidases (POD, EC 1.11.1.7) were determined. In leaves, growth was more depressed by 25 mM Na(2)SO(4) than 50 mM NaCl. The higher sensitivity of basil to Na(2)SO(4) was associated with an enhanced accumulation of H(2)O(2), an inhibition of APX, GR and POD activities (with the exception of POD under the 30-day-treatment) and a lower regeneration of reduced ascorbate (AsA) and reduced glutathione (GSH). However, the changes in the antioxidant metabolism were enough to limit oxidative damage, explaining the fact that RLR and TBARS levels were unchanged under both Na(2)SO(4) and NaCl treatment. Moreover, for both salts the 30-day-treatment reduced H(2)O(2) accumulation, unchanged RLR and TBARS levels, and enhanced the levels of antioxidants and antioxidative enzymes, thus achieving an adaptation mechanism against reactive oxygen species. PMID:20580239

Twenty compounds were isolated from the ethanol extract of Distylium racemosum branches and their inhibitory activities on tyrosinase, elastase and free radicals evaluated. The isolated compounds were identified as dibenzofurans (1-4), abscisic acid (5), 6'-O-galloylsalidroside (6), catechin derivatives (7-11), gallic acid derivatives (12-14), tyrosol (15), flavonoids (16-18), lupeol (19) and 1,2,3,6-tetragalloylglucose (20). For study of tyrosinase inhibition activities, when compared with arbutin (IC(50) 48.8??g/mL), four compounds (8, 11, 13, 17) showed higher activities, with IC(50) values of 4.8, 30.2, 40.5 and 37.7??g/mL, respectively. For the elastase inhibition test, dibenzofuran 1 showed greater activity than the positive control, oleanolic acid (IC(50) 9.7??g/mL), with an IC(50) of 7.7??g/mL. In the studies on DPPH radical scavenging activities, five compounds (11, 12, 13, 14, 15) showed higher activities than ascorbic acid (IC(50) 5.0??g/mL), with IC(50) values of 4.6, 3.9, 2.9, 3.8 and 4.7??g/mL, respectively. PMID:21351300

While bone marrow or stem cell transplantation can rescue bone marrow aplasia in patients accidentally exposed to a lethal radiation dose, radiation-induced irreversible gastrointestinal damage (GI syndrome) is fatal. We investigated the effects of ascorbic acid on radiation-induced GI syndrome in mice. Ascorbic acid (150 mg/kg/day) was orally administered to mice for 3 days, and then the mice underwent whole body irradiation (WBI). Bone marrow transplantation (BMT) 24 h after irradiation rescued mice receiving a WBI dose of less than 12 Gy. No mice receiving 14 Gy-WBI survived, because of radiation-induced GI syndrome, even if they received BMT. However, pretreatment with ascorbic acid significantly suppressed radiation-induced DNA damage in the crypt cells and prevented denudation of intestinal mucosa; therefore, ascorbic acid in combination with BMT rescued mice after 14 Gy-WBI. DNA microarray analysis demonstrated that irradiation up-regulated expressions of apoptosis-related genes in the small intestine, including those related to the caspase-9-mediated intrinsic pathway as well as the caspase-8-mediated extrinsic pathway, and down-regulated expressions of these genes in ascorbic acid-pretreated mice. Thus, pretreatment with ascorbic acid may effectively prevent radiation-induced GI syndrome.   

THP-1 cell-derived foam cells were exposed to oxidative stress through combined treatment with acetylated LDL (acLDL) and copper ions (Cu2+). The foam cells showed caspase-dependent apoptotic changes on exposure to oxidative stress for 6?h, and necrotic changes with the leakage of LDH after 24?h. KY-455, an anti-oxidative ACAT inhibitor, and ascorbic acid (VC) but not YM-750, an ACAT inhibitor, prevented apoptotic and necrotic changes. These preventive effects of KY-455 and VC were accompanied by the inhibition of lipid peroxidation in culture medium containing acLDL and Cu2+, suggesting the involvement of oxidized acLDL in apoptosis and necrosis. Foam cells accumulated esterified cholesterol (EC) for 24?h in the presence of acLDL without Cu2+, which was suppressed by KY-455 and YM-750. Fo...

Abstract in english In this investigation, we evaluated essential oils from six medicinal plants from Burkina Faso for their antiacetylcholinesterase and antioxidant abilities. The chemotype of most active were also determined. The best antiacetylcholinesterase activities were recorded for the essential oils of Eucalyptus camaldulensis (IC50 18.98 µ g/mL) and Ocimum canum (IC50 36.16 µ g/mL). Their chemotype have been related to the 1,8-cineole one. Both essential oils demonstrated a linea (more) r mixed non competitive inhibition. The essential oil of Ocimum basilicum which belong to the linalool-eugenol chemotype exhibited the best radical scavenging activity (IC50 3.82 µ g/mL) and reducing power (531.75 mg AAE/g). In comparison with gallic and ascorbic acids, O. basilicum essential oil evidenced interesting antioxidant activities. The antiacetylcholinesterase and antioxidant activities of essential oils were discussed in regard with their chemical composition.

The present study was designed to determine whether the treatment with an ethanolic extract of pomegranate (EEP) (Punica granatum) can be useful for the treatment of the deleterious effect of lead acetate (LA) administration on sperm production in rats. The effects of EEP were compared with those of ascorbic acid (AA) that is a strong antioxidant and has been shown to reverse lead-induced damage on the reproductive system. The rats were divided into five different groups: those received distilled water (control group), LA, LA with EEP, LA with AA, and EEP alone, respectively. LA administration inhibited spermatogenesis by reducing the length of the stages related to spermiation (VII and VIII) and onset of mitosis (IX-?XI). LA-treated rats also showed a reduction in epididymal sperm number ...

The effects of purple sweet potato anthocyanin (SPA) and Cordyceps mushroom extract (CME) on lipid peroxidation, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and cognitive deficits were examined. Both SPA and CME exhibited DPPH radical scavenging activities with similar potency. In contrast, only SPA was shown to effectively inhibit lipid peroxidation initiated by Fe2+ and ascorbic acid in rat brain homogenates. Furthermore, SPA markedly enhanced cognitive performance, assessed by passive avoidance test in ethanol-treated mice. Combined treatments with SPA and CME did not significantly influence the effects of SPA alone. These results demonstrate that anthocyanin prepared from purple sweet potato exhibits memory enhancing effects, which may be associated with its antioxidant properties. PMID:14609130

Somatic embryogenesis could be achieved in Themeda quadrivalvis (Linn.) O. Ktze -fodder grass species on MS medium supplemented with 2,4-D. Incorporation of putrescine in the medium stimulated embryogenesis, however its lower concentration stimulated production of non-regenerative callus. Other polyamines such as spermine and spermidine could not evoke similar response. Ascorbic acid used as antioxidant could not prevent browning in embryogenic cultures, however it stimulated embryogenesis. Inhibition of auxin polar transport by use of TIBA and HFCA reduced the embryogenic response significantly and produced distorted or abnormal embryos. Antiethylene substances such as AgNO3 and CoCl2 added in the medium adversely affected the process of embryogenesis and counteracting the stimulatory role of ethylene. PMID:19405386

The present study examined the antioxidant activity and protective effect of extracts from Asparagus racemosus roots against Lipofectamine-induced apoptosis. Five fractions from a successive extraction process ranging from non-polar to more polar solvents were obtained. The total saponin content as a marker in terms of diosgenin equivalent value of the root extracts was found to be in the range of 240-420 ?g/mg extract, with higher values for the ethanol and aqueous fractions. The antioxidant activity measured using the DPPH method in terms of mean effective concentration (EC(50)) of the aqueous fraction was found to be 600 ?g/ml as compared to 1.5 ?g/ml of ascorbic acid. It is proposed that Asparagus racemosus root extracts effectively inhibit Lipofectamine-induced apoptosis by their protective effect, and may serve as an advantageous alternative option for gene delivery. PMID:22977482

The effects of salicylic acid (SA; 1 mmol L(-1)) and ultrasound treatment (40 kHz, 10 min) either separately or combined on the chilling injury (CI) in cold-stored peach fruit ( Prunus persica Batsch cv. Baifeng) were investigated. The results showed that SA treatment alone alleviated CI during storage. Ultrasound alone had no influence, but when it was combined with SA, it resulted in greater inhibition of CI than SA alone. The activities of antioxidant enzymes, such as catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, were induced by a combination of SA with ultrasound. In addition, the combined treatment also increased the endogenous SA concentrations in peaches. These results suggested that the induced tolerance against CI by the combination of ultrasound and SA treatment in cold-stored peach fruit was related to the induction of antioxidant enzymes and the increase in the SA concentration. PMID:22229406

This study aimed to explore the antioxidant and DNA protection abilities of hydroalcoholic extracts from fruits of Anadenanthera colubrina (ACHE), Libidibia ferrea (LFHE) and Pityrocarpa moniliformis (PMHE). These extracts were tested by five antioxidant methods (phosphomolibdenium and reducing power assays; superoxide, hydrogen peroxide and nitric oxide scavenging) and DNA protection capacity. Total phenolic content was measured by Folin-Ciocalteu method. ACHE exhibited the highest phenolic content (578mg/g GAE), followed by LFHE (460mg/g GAE) and PMHE (448mg/g GAE). In phosphomolibdenium assay, ACHE showed 24.81% of activity in relation to ascorbic acid, whereas LFHE and PMHE had 21.08% and 18.05%, respectively. These plants showed high ability to inhibit reactive species tested with IC5...

A differential amperometric method for the specific determination of ascorbic acid in honey was developed by association of a flow injection analysis (FIA) system and a tubular reactor containing the ascorbate oxidase enzyme immobilised. A gold electrode modified by electrochemical deposition of palladium was employed as working electrode. Ascorbic acid was quantified in seven samples of commercial honeys using a potential of +0.60V vs. Ag/AgCl(sat). The linear dynamic range in ascorbic acid extends from 1 to 50mmolL-1, at pH 7.0. At flow rate of 1.5mLmin-1 and injecting 250mL sample volumes, a sampling frequency of 180 determinations per hour is afforded. The detection and quantification limit of this method are 0.14 and 0.49mmolL-1, respectively. The samples analyses were compared with t...

Cardiac toxicity is a major adverse effect caused by doxorubicin (DOX) therapy. Many recent studies have shown that DOX toxicity involves generation of reactive oxygen species (ROS). Although protection or alleviation of DOX toxicity can be achieved by administration of antioxidant vitamins such as ascorbic acid and vitamin E, their cardioprotective effect remains controversial. Thus alternative naturally occurring antioxidants may potentially be candidates for antioxidant therapy. In this study, we investigated the antioxidative and cytoprotective effects of Phyllanthus urinaria (PU) against DOX toxicity using H9c2 cardiac myoblasts. The total antioxidant capacity of PU (1 mg/ml) was 5306.75±461.62 FRAP value (?M). DOX IC50 values were used to evaluate the cytoprotective effects of PU ethanolic extract (1 or 10 ?g/ml) in comparison with those of ascorbic acid (VIT C, 100 ?M) and N-acetylcysteine (NAC, 100 ?M). PU treatments (1 or 10 ?g/ml) dose dependently caused rightward DOX IC50 shifts of 2.8- and 8.5-fold, respectively while treatments with VIT C and NAC increased DOX IC50 by 3.3- and 4.2-fold, respectively. Additionally, lipid peroxidation and caspase-3 activity were parameters used to evaluate cytoprotective effect. All antioxidants completely inhibited cellular lipid peroxidation and caspase-3 activation induced by DOX (1 ?M). Endogenous antioxidant defense such as total glutathione (tGSH), catalase and superoxide dismutase (SOD) activity was also modulated by the antioxidants. PU treatment alone dose dependently increased tGSH, and this effect was retained in the presence of DOX. Similar effect was observed in the assessment of catalase and SOD enzyme activity. The nuclear factor ?B (NF?B) transcription factor assay demonstrated that all antioxidants significantly inhibited DOX-induced NF?B activation. Our results suggest that PU protection against DOX cardiotoxicity was mediated through multiple pathways and this plant may serve as an alternative source of antioxidants for prevention of DOX cardiotoxicity.   

We have analyzed the stability of betalains in juices prepared from Moroccan yellow cactus pears (Opuntia ficus indica (L.) Mill.) as a function of temperature and pH. The experiments were carried out at temperatures ranging from 80 to 100 degrees C with juices at pH 3.5, 5 and 6.5. The degree of pigment retention decreased when the temperature increased. The degradation constant rates were determined for thermal degradation rates of pseudo-first order. The Arrhenius plot obtained for the degradation of betaxanthin from the yellow fruits was not linear. Regardless of the temperature of treatment, the lowest degradation was obtained for pH 5. When some stabilizers were tested for the protection of pigments, the results showed that ascorbic acid was a better protective agent at pH 3.5, increasing the protection by 40%. The inhibitive action of betalain pigments extracted from cactus pears towards corrosion of stainless steel in phosphoric acid was investigated using electrochemical polarization and electrochemical impedance spectroscopy (EIS) methods. It was found that the presence of natural pigments reduces the corrosion rate of the tested metal, especially on addition of the red pigments (97%). The inhibition efficiency increases as the pigment concentration of extracts increases. It was also found that the pigments tested act as mixed inhibitors. The inhibitive action of the extracts is discussed in term of adsorption and that such adsorption follows a Langmuir adsorption isotherm. The calculated values of the free energy of adsorption indicated that the adsorption process is spontaneous. PMID:22164774

Aluminum (Al) toxicity limits crop yield in acidic soil through affecting diverse metabolic processes, especially photosynthesis. The aim of this work was to examine the effect of Al on photosynthetic electron transport in vivo as determined by chlorophyll fluorescence and delayed fluorescence of tobacco leaves. Results showed that Al treatment inhibited the photosynthetic rate and electron transfer, and decreased photosystem (PS) II photochemical activity in a time- and concentration-dependent manner, which could not be obviously alleviated by the addition of the reactive oxygen species (ROS) scavenger ascorbic acid (AsA). These results suggested that photosynthetic electron transfer chain components, especially PSII, might be directly damaged by Al instead of in an ROS-dependent manner. Furthermore, the fluorescence imaging and biochemical analysis exhibited that Al, after entering the cells, could accumulate in the chloroplasts, which paralleled the decreased content of Fe in the chloroplast. The changes in the chlorophyll fluorescence decay curve, the delayed fluorescence decay curve and the chlorophyll fluorescence parameters indicated that Al, through interacting with or replacing the non-heme iron between Q(A) and Q(B), caused the inhibition of electron transfer between Q(A) and Q(B), resulting in PSII photochemical damage and inhibition of the photosynthetic rate. In summary, our results characterized the target site of Al phytotoxicity in photosynthetic electron transport, providing new insight into the mechanism of Al phytotoxicity-induced chloroplast dysfunction and photosynthetic damage. PMID:22611177

Cholestasis, encountered in a variety of clinical disorders, is characterized by intracellular accumulation of toxic bile acids in the liver. Furthermore, oxidative stress plays an important role in the pathogenesis of bile acids. Taurolithocholic acid (TLC) was revealed in previous studies as the most pro-oxidative bile acid. Melatonin, a well-known antioxidant, is a safe and widely used therapeutic agent. Herein, we investigated the hepatoprotective role of melatonin on lipid and protein oxidation induced by TLC alone and in combination with FeCl(3) and ascorbic acid in rat liver homogenates and hepatic membranes. The lipid peroxidation products, malondialdehyde and 4-hydroxyalkenals (MDA + 4-HDA), and carbonyl levels were quantified as indices of oxidative damage to hepatic lipids and proteins, respectively. In the current study, the rise in MDA + 4-HDA levels induced by TLC was inhibited by melatonin in a concentration-dependent manner in both liver homogenates and in hepatic membranes. Melatonin also had protective effects against structural damage to proteins induced by TLC in membranes. These results suggest that the indoleamine melatonin may potentially act as a protective agent in the therapy of those diseases that involve bile acid toxicity. PMID:20564217

We have studied the action of ascorbate (vitamin C) on human immunodeficiency virus type 1 (HIV-1), the etiological agent clinically associated with AIDS. We report the suppression of virus production and cell fusion in HIV-infected T-lymphocytic cell lines grown in the presence of nontoxic concentrations of ascorbate. In chronically infected cells expressing HIV at peak levels, ascorbate reduced the levels of extracellular reverse transcriptase (RT) activity (by greater than 99%) and of p24 antigen (by 90%) in the culture supernatant. Under similar conditions, no detectable inhibitory effects on cell viability, host metabolic activity, and protein synthesis were observed. In freshly infected CD4+ cells, ascorbate inhibited the formation of giant-cell syncytia (by approximately 93%). Exposure of cell-free virus to ascorbate at 37 degrees C for 1 day had no effect on its RT activity or syncytium-forming ability. Prolonged exposure of virus (37 degrees C for 4 days) in the presence of ascorbate (100-150 micrograms/ml) resulted in the drop by a factor of 3-14 in RT activity as compared to a reduction by a factor of 25-172 in extracellular RT released from chronically infected cells. These results indicate that ascorbate mediates an anti-HIV effect by diminishing viral protein production in infected cells and RT stability in extracellular virions. PMID:1698293

The behaviour of four known antioxidants (quercetin, ascorbic acid, catechin and caffeic acid) and their mixtures at different molar ratios was studied in view of elaborating predictions over an eventual pro-oxidant or synergistic antioxidant activity. The Co(II)-EDTA luminol chemiluminescence showed that the mixture of quercetin and ascorbic acid at ratio 2:1 had the most pronounced antioxidant activity, while that of quercetin and caffeic acid at ratio 1:2 showed the least antioxidant activity, which may be interpreted as a strong propensity for pro-oxidant behaviour. The LC-MS analysis for the two mixtures revealed a significant amount of unoxidised quercetin in the case of quercetin with ascorbic acid, whereas in the case of quercetin with caffeic acid this amount was negligible. This ...

Corrosion behaviours of AISI 304 stainless steel (SS) and Inconel-600 in dilute EDTA/citric acid/ascorbic acid solution of pH = 2.8 have been studied at 95 .deg. C with electrochemical polarization, weight loss measurement and metallographic observation. Polarization curves on AISI 304 SS were very similar to those on Inconel-600 in all solutions except a slightly higher passive current density on Inconel-600. Anodic polarization curves on AISI 304 SS and Inconel-600 in EDTA/citric acid mixture were also similar to those in EDTA solution. A passive region was found over the range of potential from-300 mV to 400 mV in EDTA solution as well as in EDTA/citric acid mixture. The passive current density in EDTA solution and in EDTA/citric acid mixture dose not depend on both kinds and concentration of chemicals in the experimental range. In case of EDTA/ascorbic acid mixture, the anodic current density was exactly the same with that in EDTA/citric acid mixture at potential below 100 mV. The higher anodic current density in EDTA/ascorbic acid mixture than in EDTA/citric acid mixture, however, was observed at potential above 100 mV. The metal oxidation current density calculated from weight loss at 400 mV in EDTA/ascorbic acid mixture was almost equal to that in EDTA/citric acid mixture. And anodic oxidation of chemicals on Pt increased with a sequence of citric acid, EDTA and ascorbic acid. So the higher anodic current in EDTA/ascorbic acid mixture than in EDTA/citric acid mixture was due to ascorbic acid oxidation. Those results indicated that EDTA, citric acid and ascorbic acid have no influence on corrosion behaviours of AISI 304 SS and Inconel-600 in the passive region. In all solutions passive current density was about 3 {approx} 5 {mu} A/cm{sup 2}, and corrosion current density was about 1 {approx} 5 {mu} A. No pitting and intergranular corrosion were observed over the range of potential from 300 mV to 400 mV.

Skeletal muscles are the largest organs in the human body, and several therapeutic trials have been conducted that included stem cell transplantation to regenerate damaged or wasted muscles. It is well known that it is essential to make a favorable microenvironment (stem cell niche) to induce the proper differentiation of the transplanted stem cells. Some drugs, such as losartan (angiotensin II type I blocker), enhance the therapeutic effects of transplanted stem cells by inhibiting fibrosis. In this study, we hypothesized that another substance, vitamin C (ascorbic acid), might improve the niche for stem cell transplantation based on its potent antioxidant effects. In both gross and microscopic observations, vitamin C depleted mice exhibited more incomplete regeneration of damaged muscles than those treated with vitamin C. Carbonylated protein groups, which are the end-products of oxidative stress, were detected in all experimental groups; however, the vitamin C-depleted groups exhibited a more potent positive reaction than that of the vitamin C-supplied groups. The difference is clearer in the presence of transplanted stem cells. Moreover, the serum total vitamin C level and ascorbic acid (AA) to dehydroascorbic acid (DHA) ratio also were decreased in the presence of transplanted adipose-derived stem cells (ASCs). Taken together, these data can be considered as proof of vitamin C utilization by cells in vivo. Meanwhile, the vitamin C-supplied groups displayed more severe fibrosis than that of the vitamin C-depleted groups. Since vitamin C is a major cofactor for the collagen synthesis, its deficiency resulted in reduced fibrosis. In conclusion, we demonstrated that vitamin C not only has a positive effect on adjusting the stem cell niche to boost muscle regeneration, but also has an adverse aspect due to its profibrotic effect. PMID:23051044

The antioxidant properties of the water and ethanol leaf extracts of kinkeliba (Combretum micranthum) were investigated, including scavenging of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (IC?? values: 8.02?±?0.34 for the ethanol extract [KE] and 9.1?±?0.28 for the water extract [KW]), the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical (IC(50) values: 7.4?±?0.14 for KE and 11.8?±?0.01 for KW) and the hydroxyl radical (58.1% for KE and 61.1% for KW). The ferric thiocyanate method, reducing power, metal chelating activity, an assay of protein oxidation and the ?-carotene-linoleic bleaching assay were also used. Butylated hydroxytoluene and ascorbic acid were used as the reference antioxidant compounds. At 20 mg mL?¹ concentration, KW and KE provided 36.8% and 75.1% inhibition of lipid peroxidation of linoleic acid emulsion, respectively. The IC?? values of the ethanol extract in ABTS and DPPH tests were significantly lower than those from the water extract. Furthermore, crude polyphenols were extracted from kinkeliba leaf with 90% ethanol solution using a water bath treatment and then purified by a macroporous resin, AB-8. The polyphenols from kinkeliba leaf were subjected to analyses by RP-HPLC and ESI-MS. The dominant polyphenols in kinkeliba leaf were identified as gallic acid, rutin trihydrate, (+)-catechin and benzoic acid. PMID:21480049

Background Some studies have shown that antioxidant ascorbic acid has renal protective effects, but the beneficial effects of contrast-induced nephropathy prevention remain to be clearly shown. Therefore, we aimed to determine whether ascorbic acid pretreatment reduces the risk of contrast-induced nephropathy in a high-risk population of patients with renal insufficiency undergoing coronary angiography. Methods We conducted a prospective, randomized, controlled trial, involving 156 consecutive patients with chronic renal insufficiency (calculated estimated glomerular filtration rate<60 mL/min/1.73 m2 and/or serum creatinine?1.1 mg/dL) undergoing coronary angiography. Patients were randomized to ascorbic acid (n=74, 3 g intravenous injection before the procedure and oral 1 g per day for 2 days after the procedure, ascorbic acid group) or sodium chloride alone (n=82, control group). All patients received pre-and postprocedure hydration. Results There was no difference between the ascorbic acid group and control group in mean peak increase in serum creatinine measured within 48 hours after coronary angiography, the primary study end point (0.012±0.146 vs 0.022±0.212 mg/dL respectively, p=0.216). The incidence of contrast-induced nephropathy, a secondary end point defined as increase of either?25% or?0.5 mg/dL in serum creatinine, was 5.4% in ascorbic acid-treated patients (4/74) and 6.3% in control group patients (6/82), a nonsignificant difference (p=0.690). There were also no differences between the 2 groups in the inhospital clinical outcomes or length of hospital stay. Conclusion Ascorbic acid pretreatment for short-term at high dose do not prevent renal function deterioration after administration of contrast medium in patients with baseline renal insufficiency undergoing coronary angiography.   

The effect of power ultrasound on the voltammetric behavior of ascorbic acid and dehydroascorbic acid at a glassy carbon electrode is described. The voltammetric characteristics of both compounds were found to be modified by ultrasonically formed radicals. In the case of dehydroascorbic acid the sin...

Abstract Selective electroanalytical responses for ascorbic acid, dopamine and uric acid at a carbon modified electrode based on 3-n-propyl-1-azonia-4-azabicyclo[2.2.2]octane silsesquioxane chloride (SiDbCl) is reported. The overlapped peaks observed at an unmodified electrode are resolved into three well defined voltammetric peaks allowing the simultaneous determination of the three species. Detection limits of 37, 0.3 and 0.1-mo-L-1 of ascorbic acid, dopamine and uric acid, respectively, were calculated from calibration curves based on differential pulse voltammetric experiments performed in Britton-Robinson buffer solution at pH-7.04.

The role of oxygen functionalities and edge plane sites on disposable screen-printed carbon electrodes (SPCE) was evaluated for simultaneous determination of dopamine, uric acid and ascorbic acid in this study. Both electrochemically preanodized and oxygen plasma treated SPCEs were adopted for the purpose of partially differentiating these two effects. Raman and XPS analyses verify that different treatment can indeed induce different surface characteristics. The electrocatalytic activity thereby increases by the substantial increase in surface bound carbon-oxygen functional groups and/or the generation of edge plane sites through surface reorientation. Possible mechanism is proposed to explain the voltammetric behavior. The peaks for dopamine, uric acid and ascorbic acid are especially wel...

Ferrous*EDTA has been found to be an effective scrubbing agent for nitric oxide gas. A major process problem is oxidation of the iron to the ferric species, leading to a significant decrease in NO{sub x}-removal capability. Argonne National Laboratory discovered a class of organic compounds that, when used with ferrous*EDTA in a sodium carbonate chemistry, could maintain high levels of NO{sub x} removal. However, those antioxidant/reducing agents (A/R) are not effective in a lime-based chemistry. In recent reports, it has been found that ascorbic acid and related compounds are capable of maintaining stable NO{sub x} removals of about 50% (compared with about 15% without the agent) in a lime-based FGD chemistry with Fe(II)*EDTA. It is believed that the improved performance of Fe(II)*EDTA is due to the catalytic action of ascorbate in the Fe(III)*EDTA reduction system, where Fe(III)*EDTA is reduced by ascorbate and oxidized ascorbate is then reduced back to the ascorbate by sulfite/bisulfite anions, which come from the dissolution of SO{sub 2} in the flue gas. In the present work, the kinetics of the reduction of ferric chelate by ascorbate and reduction of oxidized ascorbate by sulfite/bisulfite anions at a typical flue-gas scrubber-system operating temperature ({approximately}55 C) have been determined.

Abstract:- This research studied the influence of treatment with ascorbic acid, citric acid, and calcium lactate dipping and cassava starch edible coatings on quality parameters and shelf life of fresh-cut pineapple in slices during 12 d at 5 C. After previous tests, the treatments selected for this study were samples dipped into antibrowning solution with 0.5% of ascorbic acid and 1% of citric acid, with and without 2% of calcium lactate and coated with 2% of cassava starch suspensions. Changes in weight loss, juice leakage, mechanical properties (stress at failure), color parameters (L* and H*), ascorbic acid content, sensory acceptance, and microbial growth of fruits were evaluated. Samples only treated with antibrowning agents were used as control. Edible coatings with and without calc...

The antioxidant properties of prenylflavones, isolated from Artocarpus heterophyllus Lam., was evaluated in this study. Among them, artocarpine, artocarpetin, artocarpetin A, and cycloheterophyllin diacetate and peracetate had no effect on iron-induced lipid peroxidation in rat brain homogenate. They also did not scavenge the stable free radical 1,1-diphenyl-2-picrylhydrazyl. In contrast, cycloheterophyllin and artonins A and B inhibited iron-induced lipid peroxidation in rat brain homogenate and scavenged 1,1-diphenyl-2-picrylhydrazyl. They also scavenged peroxyl radicals and hydroxyl radicals that were generated by 2,2'-azobis(2-amidinopropane) dihydrochloride and the Fe3+-ascorbate-EDTA-H2O2 system, respectively. However, they did not inhibit xanthine oxidase activity or scavenge superoxide anion, hydrogen peroxide, carbon radical, or peroxyl radicals derived from 2,2'-azobis(2,4-dimethylvaleronitrile) in hexane. Moreover, cycloheterophyllin and artonins A and B inhibited copper-catalyzed oxidation of human low-density lipoprotein, as measured by fluorescence intensity, thiobarbituric acid-reactive substance and conjugated-diene formations and electrophoretic mobility. It is concluded that cycloheterophyllin and artonins A and B serve as powerful antioxidants against lipid peroxidation when biomembranes are exposed to oxygen radicals. PMID:9667491

In plants, algae, and many bacteria, the heme and chlorophyll precursor, [delta]-aminolevulinic acid (ALA), is synthesized from glutamate in a reaction involving a glutamyl-tRNA intermediate and requiring ATP and NADAPH as cofactors. In particulate-free extracts of algae and chloroplasts, ALA synthesis is inhibited by heme. Inclusion of 1.0 mM glutathione (GSH) in an enzyme and tRNA extract, derived from the green alga Chlorella vulgaris, lowered the concentration of heme required for 50% inhibition approximately 10-fold. The effect of GSH could not be duplicated with other reduced sulfhydryl compounds, including mercaptoethanol, dithiothreitol, and cysteine, or with imidazole or bovine serum albumin, which bind to heme and dissociate heme dimers. Absorption spectroscopy indicated that heme was fully reduced in incubation medium containing dithiothreitol, and addition of GSH did not alter the heme reduction state. Oxidized GSH was as effective in enhancing heme inhibition as the reduced form. Co-protoporphyrin IX inhibited ALA synthesis nearly as effectively as heme, and 1.0 mM GSH lowered the concentration required for 50% inhibition approximately 10-fold. Because GSH did not influence the reduction state of heme in the incubation medium, and because GSH could not be replaced by other reduced sulfhydryl compounds or ascorbate, the effect of GSH cannot be explained by action as a sulfhydryl protectant or heme reductant. Preincubation of enzyme extract with GSH, followed by rapid gel filtration, could not substitute for inclusion of GSH with heme during the reaction. The results suggest that GSH with heme during the reaction. The results suggest that GSH must specifically interact with the enzyme extract in the presence of the inhibitor to enhance the inhibition. 48 refs., 7 figs., 4 tabs.

This article describes an undergraduate electrochemistry laboratory experiment in which the students measure the L-ascorbic acid content of a real sample. Gold electrodes modified with self-assembled monolayers (SAMs) of thioctic acid and cysteamine are prepared to study the effects of surface modification on the electrode reaction of L-ascorbic acid at neutral pH. Cyclic voltammograms of L-ascorbic acid are different on these electrodes, owing to the different surface charge of the SAMs. Cysteamine-modified electrodes give a sharper oxidation peak at a smaller overpotential and thus are more suitable for measuring the concentration of L-ascorbic acid in an aqueous solution. A linear calibration curve is obtained using such an electrode, permitting the determination of L-ascorbic acid content in a vitamin C tablet. This experiment provides a means for teaching the basics of voltammetry, teaching the effect of chemical modification of the electrode surface on the electrode reaction, and providing students with hands-on experience in fabricating and utilizing electrochemical sensors. Additionally, it can be completed within three hours and is suitable as an undergraduate laboratory experiment. (Contains 4 figures.)

The aim of the present study was to evaluate the potential pharmacological and toxicological properties of (E)-1-(1-(methylthio)-1-(selenopheny) hept-1-en-2-yl) pyrrolidin-2-one (compound 1), an organoselenium compound. In vitro experiments showed that compound 1 presented a reduction in the lipid peroxidation induced by Fe²? in thiobarbituric acid-reactive species (TBARS) production, and in the generation of reactive species caused by Fe²?/malonate in DCFH-DA oxidation. The high dose (500 mg/kg) induced an increase on ALT but not on AST activity. Hepatic, but not cerebral, ?-ALA-D activity from mice treated with 500 mg/kg presented a significant inhibition. Brain catalase activity was significantly inhibited by 100 mg/kg whereas hepatic catalase activity showed a significant increase at all doses. Hepatic lipid peroxidation was diminished only at lowest dose (100 mg/kg) whereas for brain tissue, all doses induced a significant reduction in TBARS levels. Brain and liver ascorbic acid contents were increased only at highest dose of compound 1. Urea and creatinine levels were not significantly altered by treatments. This is a promising compound with antioxidant activity and low toxicity, suggesting the potential beneficial activity of compound 1 against oxidative damage in many parameters studied in rats and mice. PMID:22411701

Physalis peruviana (PP) is a widely used medicinal herb for treating cancer, malaria, asthma, hepatitis, dermatitis and rheumatism. In this study, the hot water extract (HWEPP) and extracts prepared from different concentrations of ethanol (20, 40, 60, 80 and 95% EtOH) from the whole plant were evaluated for antioxidant activities. Results displayed that at 100 ?g/ml, the extract prepared from 95% EtOH exhibited the most potent inhibition rate (82.3%) on FeCl2–ascorbic acid induced lipid peroxidation in rat liver homogenate. At concentrations 10—100 ?g/ml, this extract also demonstrated the strongest superoxide anion scavenging and inhibitory effect on xanthine oxidase activities. In general, the ethanol extracts revealed a stronger antioxidant activity than ?-tocopherol and HWEPP. Compared to ?-tocopherol, the IC50 value of 95% EtOH PP extract was lower in thiobarbituric acid test (IC50=23.74 ?g/ml vs. 26.71 ?g/ml), in cytochrome c test (IC50=10.40 ?g/ml vs. 13.39 ?g/ml) and in xanthine oxidase inhibition test (IC50=8.97 ?g/ml vs. 20.68 ?g/ml). The present study concludes that ethanol extracts of PP possess good antioxidant activities, and the highest antioxidant properties were obtained from the 95% EtOH PP.