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

饮食中的诱变和致癌抑制物特别令人感兴趣，因为它们可能对人类癌症预防有用。根据这一观点，发酵牛奶中遇到的乳酸菌菌株在营养、治疗、抗肿瘤以及抗癌功能方面都具有很高的价值。最近的研究结果表明，乳酸菌对N-亚硝胺等各种诱变剂/致癌物也具有抗突变活性。在本研究中，我们首先检测了从印度尼西亚和蒙古的发酵乳制品“dadih”和“kefir”中分离出的乳酸菌的结合能力。所有菌株对致突变色氨酸热解产物，即色氨酸热解产物Trp-P1和Trp-P2均表现出较强的结合能力。其中，乳酸乳球菌亚种T-80对这类诱变剂的结合能力最强，但随着胰酶浓度的增加，结合能力降低。作为实验的第二部分，我们以鼠伤寒沙门氏菌TA 98链霉菌素依赖菌株(SD 510)为指示菌，检测了上述发酵乳制品对N-亚硝胺(NPIP)、N-亚硝基二甲胺(NDMA)、N-亚硝基二乙胺(NDEA)和N-亚硝基吡啶(NPYR)的抗突变作用。40株菌株对NDEA和NDMA有抗突变活性，但对NPIP和NPYR无抗突变活性。

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.