Sah N K, Kumar S, Subramanian M, Devasagayam T P
Department of Botany, R.D. College, Bihar, India.
Biochem Mol Biol Int. 1995 Feb;35(2):291-6.
Superoxide radical (O2-.), generated by the xanthine-xanthine oxidase system, induces significant amount (20%) of single-strand breaks in plasmid pBR322 DNA. This is almost completely inhibited by its specific scavenger, superoxide dismutase. The biological antioxidants, at near physiological concentrations show great variation in their modulation of DNA damage induced by O2-.. The thiols glutathione, cysteine and dithiothreitol do not protect DNA, instead they greatly enhance the strand-breaking activity of this free radical. However, the lipid soluble antioxidants tannic acid, butein, canthaxanthin, beta-carotene and lipoate offered significant protection to plasmid DNA against O2-.. Since O2-. is the most abundant reactive oxygen species generated, the above mentioned modulating abilities of biological antioxidants may have significant biological implications.
由黄嘌呤 - 黄嘌呤氧化酶系统产生的超氧阴离子自由基（O2-.）可在质粒pBR322 DNA中诱导产生大量（20%）的单链断裂。这几乎完全被其特异性清除剂超氧化物歧化酶所抑制。在接近生理浓度时，生物抗氧化剂对O2-.诱导的DNA损伤的调节作用表现出很大差异。硫醇类物质谷胱甘肽、半胱氨酸和二硫苏糖醇不能保护DNA，相反，它们会大大增强这种自由基的链断裂活性。然而，脂溶性抗氧化剂单宁酸、紫铆因、角黄素、β-胡萝卜素和硫辛酸能为质粒DNA提供显著的保护，使其免受O2-.的损伤。由于O2-.是产生的最丰富的活性氧物种，上述生物抗氧化剂的调节能力可能具有重要的生物学意义。
