In order to investigate the functions of reductones, their mutagenic action was studied with and without cupric ion using Salmonella typhimurium TA 100 strain. Triose reductone (TR), which has the simplest enediol structure among reductones, induced a notable frequency of his+ revertants at 2.5 or 5 mM. The addition of cupric ion to TR at a molar ratio of 1:1, 000 lowered the most active concentration of TR to 1mM. Another typical enediol reductone, ascorbic acid (AsA), had no detectable mutagenic action by itself. However, the treatment of the bacteria with a freshly mixed solution of 5mM AsA and 1 or 5 μM cupric ion exerted effective mutagenic action. The mutagenecity of these reductones, with or without cupric ion, occurred at a relatively narrow range of concentrations. Furthermore, the frequency induced by these reductones was extremely low compared with that by N-methyl-N' nitro-nitrosoguanidine or the mixture of AsA and cupric ion which was used by STICH et al. (STICH, H. F., KARIM, J., KOROPATONIC, J., and LO, L., Nature, 260, 722 (1976)). On the other hand, ascorbyl-3-phosphate, in which 3-OH groups of AsA was esterified with phosphate, had no effective mutagenic function even in the presence of cupric ion. These findings indicated that enediol structure in reductones played an essential role in the mutagenesis. The higher concentrations of reductones or the mixture with cupric ion seemed to cause the lethal effect on the bacteria. Control with or without cupric ion exerted no mutagenic action.
