Studies on lactic acid bacteria having antimutagenicity toward N-nitroso compounds

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Dietary inhibitors of mutagenesis and carcinogenesis are of particular interest, because they may be useful for human cancer prevention. In respect with that view, lactic acid bacterial strain encountered in fermented milk are being known to have high value in nutritional, therapeutic, antitumor as well as anticancer functions. Recent findings have shown that lactic acid bacteria also performed antimutagenic activity against various kinds of mutagens/carcinogens such as N-nitrosamins.In the present research, we first examined binding abilities of lactic acid bacteria isolated from "dadih" and "kefir" , which are fermented milk products in Indonesia and Mongolian, respectively. All the isolates exhibited high binding abilities toward mutagenic tryptophane pyrolysates, viz., Trp-P1 and Trp-P2. Among them, Lactococcus lactis subsp.lactis T-80 exhibited the highest binding ability toward such mutagens, but the binding decreased with the increase of trypsin concentration. The mechanism of binding of the T-80 strain with such mutagens was supposed to be due to the formation of hydrophobic bonds.As a second part of experiment, we examined antimutagenicity of the lactic acid bacteria isolated above mentioned fermented milk products toward N-nitrosamines, viz., N-nitrosopiperidine (NPIP) , N-nitrosodimethylamine (NDMA) , N-nitrosodiethylamine (NDEA) and N-nitrosopyrolidine (NPYR) using a Salmonella typhimurium TA 98 streptomycin-dependent strain (SD 510) as an indicator bacteria. 40 strains examined exhibited antimutagenic activity against NDEA and NDMA,but not against NPIP and NPYR.