Nikaido H, Mishima H K, Moriishi M, Kitamura S, Tatsumi K
Department of Ophthalmology, Hiroshima University School of Medicine, Japan.
Jpn J Ophthalmol. 1992;36(1):103-7.
By microsomes obtained from bovine ciliary body, 1,1-diphenylhydrazine was oxidized to N-nitrosodiphenylamine in the presence of NADPH. This reaction was stimulated by riboflavin which was recognized to be an electron carrier. The oxidizing activity by microsomes was markedly inhibited by superoxide dismutase, but not by SKF 525-A or carbon monoxide. Similarly, the oxidation of 1,1-diphenylhydrazine to its corresponding nitrosamine occurred in varying degrees when the hydrazine derivative was exposed to visible light in the presence of photosensitizers such as riboflavin, flavin adenine dinucleotide, flavin mononucleotide, lumiflavin, lumichrome, NAD+, NADH, NADP+, or NADPH. The photochemical oxidation was inhibited by active oxygen-scavengers such as superoxide dismutase, L-ascorbic acid or alpha-tocopherol. The superoxide radical involved in the photochemical reaction was determined by measuring the oxidation of epinephrine to adrenochrome. The oxidation of epinephrine was well correlated to that of 1,1-diphenylhydrazine. Thus, the present study provided evidence that the superoxide radical is responsible for the oxidation of a hydrazine derivative to a corresponding nitrosamine by ocular tissue microsomes and by photosensitizers.
通过从牛睫状体获得的微粒体，在NADPH存在的情况下，1,1 - 二苯基肼被氧化为N - 亚硝基二苯胺。该反应受到核黄素的刺激，核黄素被认为是一种电子载体。微粒体的氧化活性受到超氧化物歧化酶的显著抑制，但不受SKF 525 - A或一氧化碳的抑制。同样，当肼衍生物在核黄素、黄素腺嘌呤二核苷酸、黄素单核苷酸、发光黄素、发光色素、NAD +、NADH、NADP +或NADPH等光敏剂存在的情况下暴露于可见光时，1,1 - 二苯基肼会不同程度地氧化为相应的亚硝胺。光化学氧化受到超氧化物歧化酶、L - 抗坏血酸或α - 生育酚等活性氧清除剂的抑制。通过测量肾上腺素氧化为肾上腺色素来确定光化学反应中涉及的超氧自由基。肾上腺素的氧化与1,1 - 二苯基肼的氧化密切相关。因此，本研究提供了证据，表明超氧自由基是导致肼衍生物被眼组织微粒体和光敏剂氧化为相应亚硝胺的原因。
