Babu, T Sudhakar; Tripuranthakam, Sridevi; Greenberg, Bruce M
Metals and polycyclic aromatic hydrocarbons (PAHs) are known to be toxic to plants. Because metals and PAHs often are cocontaminants in the environment, plants can be subjected to damage caused by their combined effects. We recently found that copper and an oxygenated PAH (1,2-dihydroxyanthraquinone [1,2-dhATQ]) synergistically are toxic to plants. This synergistic toxicity was linked indirectly to production of reactive oxygen species (ROS). In this study, plant growth, chlorophyll pigments, protein accumulation, and ROS production were chosen as endpoints to assess the mechanism of toxicity of copper and 1,2-dhATQ to Lemna gibba in more detail. Because copper and PAHs can generate ROS, we assayed for specific antioxidant enzymes: Superoxide dismutase (SOD), glutathione reductase (GR), and ascorbate peroxidase (APX). Copper treatment at a concentration that did not cause growth inhibition resulted in upregulation of Mn SOD, Cu-Zn SOD, and APX. At a level that moderately was toxic to plants, 1,2-dhATQ did not alter significantly the levels of these antioxidant enzymes. However, a synergistically toxic mixture of copper plus 1,2-dhATQ upregulated Cu-Zn SOD, Mn SOD, and GR, although APX activity was downregulated. When plants were treated with the ROS scavenger dimethyl thiourea (DMTU), enhanced toxicity and formation of ROS caused by the mixture both were diminished substantially. However, 1,2-dhATQ toxicity was not affected significantly by DMTU. Based on this study, the toxicity caused by the mixture of copper plus 1,2-dhATQ directly can be connected to elevated levels of ROS. PMID:16445081
Ramamoorthy, Siva; Mudgal, Gaurav; Rajesh, D; Nawaz Khan, F; Vijayakumar, V; Rajasekaran, C
Oldenlandia umbellata L., commonly known as 'chay root', belongs to the family Rubiaceae and is one of the unexplored dye-yielding plants. The roots from this plant are the sources of red dye. Extraction protocol and dye characterisation have not been completely studied so far in this plant. Hence, in this article we have used UV spectrophotometry, thin layer chromatography, GC-MS, high-performance liquid chromatography and NMR to identify the five major colouring compounds, including 1,2,3-trimethoxyanthraquinone, 1,3-dimethoxy-2-hydroxyanthraquinone, 1,2-dimethoxyanthraquinone, 1-methoxy-2-hydroxyanthraquinone and 1,2-dihydroxyanthraquinone. It showed application feasibility as a new pH indicator. PMID:19731140
Akhtar, Tariq A; Lees, Hazel A; Lampi, Mark A; Enstone, Daryl; Brain, Richard A; Greenberg, Bruce M
Plants accumulate flavonoids in response to a myriad of environmental challenges, especially when exposed to ultraviolet (UV) radiation or situations causing oxidative stress. However, the origin and nature of the signal triggering their accumulation remain obscure. In this study, a group of flavonoids belonging to the flavone class was identified in Lemna gibba (duckweed). These flavones accumulated upon exposure to UV radiation, low temperature, copper and the photosynthetic electron transport (PET) inhibitors 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) and 1,2-dihydroxyanthraquinone (DHATQ). All of these stressors were also shown to promote PET chain (PETC) reduction; however, in the co-presence of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) or a light regime that oxidized the PETC, flavonoid accumulation ceased. Chloroplast-derived reactive oxygen species (ROS) were not associated with all of the stress conditions that promoted both PETC reduction and flavonoid synthesis, indicating that ROS were not a strict requisite for flavonoid accumulation. Transcripts for the flavonoid biosynthetic genes, chalcone synthase (CHS) and chalcone isomerase, were similarly responsive to the PETC redox state, as were a panel of transcripts revealed by differential display PCR. Collectively, these results provide evidence that PETC redox status is one of the factors affecting flavonoid biosynthesis. PMID:20199616
康文艺; 张丽; 宋艳丽
目的:寻找茜草中抑制α-葡萄糖苷酶活性的成分.方法:利用体外抑制α-葡萄糖苷酶活性模型进行追踪,采用各种色谱法分离,运用多种谱学技术鉴定结构,并对活性化合物进行酶抑制动力学研究.结果:茜草三氯甲烷提取物具有很高的活性,从中分离出3个具抑制α-葡萄糖苷酶活性的蒽醌类化合物,分别鉴定为:1,3-二羟基-2-甲基蒽醌(1),1-羟基-2一甲基葸醌(2)和1,2-二羟基蒽醌(3),其中化合物3(IC_(50)=7.97 mg·L~(-1))活性最好,与1(IC_(50)=35.96 mg·L~(-1))和2(IC_(50)=15.98 mg·L~(-1))的活性都明显高于阳性对照阿卡波糖(IC_(50)=1 081.27 mg·L~(-1)).化合物1和2为竞争性抑制类型.结论:化合物1-3为首次报道对α-葡萄糖苷酶抑制活性.%Objective: To search α-glucosidase inhibitors from Rubia cordifolia. Methed: The α-glucosidase inhibitors were isolated by the column chromatographic techniques and the bioassay-guided method in vitro. A combination of MS and NMR spectrosco-py was used to identify the chemical structures. The inhibitory kinetics of the inhibitors were also investigated. Result: The chloroform extract showed high inhibitory activity,and three active compounds were isolated and identified as 1,3-dihydroxy-2-methylanthraquinone (1), 1-hydroxy-2-methylanthraquinone (2) and 1,2-dihydroxyanthraquinone (3). The IC_(50) values of compound 1-3 were all lower than that of acarbose. Compound 1 and 2 shown competitive type manner on α-glucosidase, whereas compound 3 shown noncompetitive type model. Conclusion: Compounds 1-3 as strong inhibitors of α-glucosidase were reported for the first time.