茶多酚对脂氧合酶介导酚噻嗪类与联苯胺等氧化相互作用的抑制

Effect of tea polyphenols on soybean lipoxygenase-mediated interaction of phenothiazines with benzidine and other xenobiotics

目的研究茶多酚(GTP)及其单体表没食子儿茶素没食子酸酯(EGCG)对脂氧合酶(LOX)介导酚噻嗪类化合物与联苯胺(BZ)等相互作用的影响,探讨其通过抑制脂氧合酶介导这种氧化增强作用的新机制而发挥防癌和对抗化学物其他毒作用的可能性。方法用分光光度法和电子自旋共振波谱仪(ESR)检测氧化产物和自由基。结果大豆脂氧合酶(SLO)能介导酚噻嗪类对BZ等化学物氧化的增强作用。GTP、EGCG等对SLO介导的氧化增强效应均有抑制作用,其抑制能力有显著意义的高于LOX抑制剂棉子酚、还原剂二硫苏糖醇、谷胱甘肽、自由基清除剂丁羟基茴香醚和丁羟基甲苯。结论SLO介导产生的酚噻嗪阳离子自由基可增强BZ等的氧化作用;GTP和EGCG可明显抑制此氧化增强效应。

Objective To research the effects of tea polyphenols （GTP） and its monomer（-）-epigallocatechin gallate（EGCG） on the interaction of phenothiazines with benzidine （BZ）and other xenobiotics mediated by lipoxygenase （LOX）, and to raise a novel possible mechanism of anti-toxicity and anti-cancer effects of GTP and EGCG by inhibiting lipoxygenase-catalyzed stimulation of xenobiotics oxidation. Methods The oxidation products and free radical intermediates were detected by spectrophotometry and electron spin resonance （ESR） spectrometer. Results Phenothiazines increased the oxidation of BZ and other xenobiotics mediated by soybean lipoxygenase （SLO）. GTP, EGCG and other moderators all inhibited the above enzymatic reaction of oxidation enhancement and the inhibitive effect of EGCG was more significant potent than LOX inhibitor gossypol, reducer dithiothreitol, glutathione and free radical scavenger, butylated hydroxyanisole and butylated hydroxytoluene. Conclusions Phenothiazines cation free radical generated by SLO stimulated the oxidation of benzidine and other xenobiotics; GTP and EGCG Could inhibit the oxidation enhancement.