Analyses of radioprotective action and cytotoxicity of various sulfhydryl compounds in cultured mouse L cells.

*疋 田光史,堀 川正克,森 俊雄:金 沢大学薬学部放射薬品化学教室,金 沢市宝町13-1〒920 The radioprotective action and cytotoxicity of various sulfhydryl compounds ; 2-mercapto propionylglycine (MPG), 2-mercaptopropionylglycine-amide (MPG-amide), 2-mercaptopropionyl phenylalanine (MPPA), 2-mercaptopropionylphenylglycine (MPPG), 3-mercaptopropionylglycine (3-MPG), AET, cysteine and cysteamine were compared in irradiated and unirradiated mouse L cells using colony forming ability as a criterion . It was indicated that the sulfhydryl com pounds divided into three classes, according to their radioprotective action and toxicity. Most effective radioprotection was obtained by cysteamine and cysteine , followed by AET and MPG amide in that order. Toxicity of these sulfhydryl compounds were generally observed in concentrations in the range of 0.1-2 mM, while they are much less toxic and effectively radi oprotective in higher concentration, especially in cysteamine and cysteine. On the other hand, MPG, MPPA, MPPG and 3-MPG were all non-toxic and generally ineffective in protecting ir radiated cells, except that MPG in concentrations around 0.02 mM and 15 mM and MPPA and 3-MPG around 15 mM have a slight but significant protective action .