Inhibition of mitochondrial respiratory chain by arylthiolated 2,3-ethylenedioxy-1,4-benzoquinones.
作者:Koichi MORI、Shihoko HAMA、Fumino KATO、Tadashi OKAMOTO、Takeo KISHI、Hiroteru SAYO
DOI:10.1248/cpb.38.1100
日期:——
A series of arylthiolated 2, 3-ethylenedioxy-1, 4-benzoquinones as a coenzyme Q (CoQ) antagonist was tested for inhibition of succinate oxidase and reduced nicotinamide adenine dinucleotide (NADH) oxidase systems in the mitochondrial respiratory chain. The following characteristics were revealed : (1) 2, 3-ethylenedioxy, 5-arylthio and 5, 6-diarylthio groups were confirmed to be favorable for inhibition of both systems; (2) these analogs were more effective in the succinate oxidase system than in the NADH oxidase system; (3) 4' substituents on the benzene side ring had little effect on inhibitory activity; (4) the acting sites of these analogs had no strict stereospecificity. The reduced minus oxidized difference spectra revealed that these analogs inhibited the succinate oxidase system at the site between succinate and CoQ, and the NADH oxidase system at the site after cytochrome a+a3, suggesting these analogs might act as antagonists of CoQ in the succinate oxidase system. However, 5-(4'-nitrophenylthio)-2, 3-ethylenedioxyl-1, 4-benzoquinone (If) strongly inhibited only the succinate oxidase system at the site after cytochrome a+a3.
研究人员测试了一系列芳硫基 2,3-乙烯二氧基-1,4-苯醌类化合物作为辅酶 Q(CoQ)拮抗剂对线粒体呼吸链中琥珀酸氧化酶和还原型烟酰胺腺嘌呤二核苷酸(NADH)氧化酶系统的抑制作用。结果表明:(1) 2, 3-乙烯二氧基、5-芳硫基和 5, 6-二芳硫基被证实对这两个系统都有抑制作用;(2) 这些类似物对琥珀酸氧化酶系统的抑制作用大于对 NADH 氧化酶系统的抑制作用;(3) 苯侧环上的 4' 取代基对抑制活性的影响很小;(4) 这些类似物的作用位点没有严格的立体特异性。还原减氧化差谱显示,这些类似物在琥珀酸与 CoQ 之间的部位抑制琥珀酸氧化酶系统,在细胞色素 a+a3 之后的部位抑制 NADH 氧化酶系统,表明这些类似物可能在琥珀酸氧化酶系统中作为 CoQ 的拮抗剂。然而,5-(4'-硝基苯硫基)-2,3-亚乙二氧基-1,4-苯醌(If)仅能强烈抑制细胞色素 a+a3 后部位的琥珀酸氧化酶系统。