Mutagenicity of Potassium Alkanediazotates in Chinese Hamster V79 Cells and Their Alkylating Activity.
作者:Satoko UKAWA-ISHIKAWA、Masako SEKI、Masataka MOCHIZUKI
DOI:10.1248/bpb.22.577
日期:——
Alkanediazohydroxides are the key intermediates of carcinogenic N-nitroso compounds, and exist as geometrical isomers. In this paper, the mutagenicity and cytotoxicity of (E)- and (Z)-potassium alkanediazotates, precursors of alkanediazohydroxides, in Chinese hamster V79 cells were investigated. Mutagenic and cytotoxic activities of (E)-diazotates were dose-dependent, and activity decreased with an increase in the alkyl chain length; methyl>ethyl>propyl, butyl. On the other hand, (Z)-diazotates were less mutagenic and cytotoxic than(E)-diazotates, however (Z)-potassium methanediazotate did show weak mutagenicity. To compare chemical reactivity with biological activity, alkylating activity towards incotinamide in an aqueous phosphate buffer system was evaluated as an index of the chemical reactivity of diazotates. Using a fluorometric HPLC method, alkylated nicotinamides were detected with high sensitivity in the reaction with all diazotates tested. The alkylting activity of (Z)-methanediazotate was higher than that of the corresponding (E)-diazotate, but the other isomers with ethyl, propyl and butyl groups had similar reactivity under the conditions used. The activity decreased by increasing the alkyl chain-length, which correlated well with the mutagenicity in V97 cells and also with that in Salmonella typhimurium, which we reported earlier. The results for (E)-diazotates were similar to the corresponding N-nitroso-N-(hydroxymethyl)alkylamines, further supporting the notion that α-hydroxy nitrosamines decompose through alkanediazohydroxide and alkylate DNA, and suggests that geometrical isomerism influences the carcinogenicity of N-nitroso compounds in mammals.
烷二氧基化物是致癌 N-亚硝基化合物的关键中间体,并以几何异构体的形式存在。本文研究了烷二多氧化合物的前体--(E)-烷二多氧钾盐和(Z)-烷二多氧钾盐在中国仓鼠 V79 细胞中的诱变性和细胞毒性。(E)-噻唑酸钾的致突变活性和细胞毒性活性与剂量有关,活性随烷基链长度的增加而降低;甲基>乙基>丙基和丁基。另一方面,(Z)-重氮酸盐的致突变性和细胞毒性低于(E)-重氮酸盐,但(Z)-甲二重氮酸钾确实表现出微弱的致突变性。为了比较化学反应活性和生物活性,对重氮酸盐的化学反应活性进行了评估,将其作为重氮酸盐在磷酸水缓冲体系中对incotinamide的烷基化活性指标。采用荧光高效液相色谱法,在与所有测试的重氮酸盐发生反应时,都能高灵敏度地检测到烷基化的烟酰胺。在所用条件下,(Z)-甲基重氮酸酯的烷基化活性高于相应的(E)-重氮酸酯,但带有乙基、丙基和丁基的其他异构体具有相似的反应活性。活性随着烷基链长的增加而降低,这与 V97 细胞的诱变性以及我们早先报告的鼠伤寒沙门氏菌的诱变性密切相关。(E)-重氮酸盐的结果与相应的 N-亚硝基-N-(羟甲基)烷基胺相似,进一步支持了 α-羟基亚硝胺通过烷二羟基分解并烷化 DNA 的观点,并表明几何异构体影响了 N-亚硝基化合物在哺乳动物中的致癌性。