PEROXYGENASE METABOLISM OF N ACETYLBENZIDINE BY PROSTAGLANDIN H SYNTHASE

N ′-（3 ′-单磷酸脱氧鸟苷-8-基）-N-乙酰基联苯胺（1A）是一种 联苯胺暴露的生物标志物，起始的终产物，和 产生遗传毒性损伤。 前列腺素H合酶（PHS）激活 芳香胺膀胱癌致癌物N-乙酰联苯胺（ABZ）形成 1A. 本研究探讨了ABZ代谢PHS的机制。 花生四烯酸（0.2 mM）与公羊精囊微粒体转化 3 H-ABZ（0.06 mM）至4 '-硝基-4-乙酰氨基联苯（总量的21%） 通过HPLC测定代谢）。 与抗坏血酸、N '-羟基-N-乙酰基联苯胺 （N 'HA）是主要产物，并通过ESI/MS/MS鉴定。 用H2 O2（0.3mM）观察结果。 氰化物（10 mM），a 过氧化物酶抑制剂，阻止代谢，但细胞色素P-450 抑制剂SKF-525 A、呋拉茶碱或β-萘黄酮（0.1 mM） 没有 DMPO缺乏作用表明， 不涉及电子转移产生的。 H2 O2、氧气 未检测到摄取。 既不是羟基化合物也不是超氧化物 是氧结合的来源，因为甘露醇和超氧化物 歧化酶没有抑制作用。 来确定氧气的来源 引入ABZ，使用[18 O] H2 O2。 18 O-N 'HA富集 与[18 O] H2 O2碱性氧化甲萘醌相比， 18 O-环氧化物。 N 'HA富集类似于环氧化物。 因此，PHS 通过过氧化代谢ABZ。 N 'HA可在PHS期间形成1A ABZ的代谢

N'-(3'-Monophospho-deoxyguanosin-8-yl)-N-acetylbenzidine (1A) is a biomarker of benzidine exposure, an endproduct of initiation, and produces genotoxic lesions. Prostaglandin H synthase (PHS) activates the aromatic amine bladder carcinogen N-acetylbenzidine (ABZ) to form 1A. This report examines the mechanism of PHS metabolism of ABZ. Arachidonic acid (0.2 mM) with ram seminal vesicle microsomes convert 3H-ABZ (0.06 mM) to 4'-nitro-4-acetylaminobiphenyl (21% of total metabolism by HPLC). With ascorbic acid, N'-hydroxy-N-acetylbenzidine (N'HA) was the major product and was identified by ESI/MS/MS. Similar results were observed with H2O2 (0.3 mM). Cyanide (10 mM), a peroxidase inhibitor, prevented metabolism, but cytochrome P-450 inhibitors SKF-525A, furafylline, or (-naphtho-flavone (0.1 mM) did not. The lack of effect of DMPO suggests that radical products generated by electron transfer were not involved. With H2O2, oxygen uptake was not detected. Neither h ydroxyl ra dicals nor superoxide are sources of oxygen incorporation, because mannitol and superoxide dismutase did not inhibit. To determine the source of oxygen incorporated into ABZ, [18O]H2O2 was used. 18O-N'HA enrichment was compared to [18O]H2O2 alkaline oxidation of menadione to its 18O-epoxide. N'HA enrichment was similar to the epoxide. Thus, PHS metabolizes ABZ by peroxygenation. N'HA may form 1A during PHS metabolism of ABZ.