Protective Effect of a Lactobacillus salivarius Strain of Human Origin

The protective effect of a Lactobacillus salivariusstrain from human faeces (HA8) was evaluated against the cytotoxicity of N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrosodibutylamine (NDBA) and N-nitrosopiperidine (NPIP) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. L. salivariusHA8 strain showed a moderate protective effect against NPYR and weak against NDBA and NPIP. No protective effect against cytotoxicity of NDMA was observed at the bacterial population used. To test the effect of L. salivariusHA8 on cytokine production (interleukin-1 ± (IL-1 ±), interleukin-8 (IL-8) and tumour necrosis factor alpha (TNF-≥)), the human macrophage cell line (THP-1) was cultured in the presence and absence of lipopolysaccharide (LPS). L. salivariusHA8 induced IL-1 ±, IL-8 and TNF-≥ releases when cells were stimulating with and without LPS.

Protective effects of organosulfur compounds towards N-nitrosamine-induced DNA damage in the single-cell gel electrophoresis (SCGE)/HepG2 assay

The aim of this study was to investigate the protective effect of organosulfur compounds towards N-nitrosamine-induced DNA damage in the single-cell gel electrophoresis (SCGE)/HepG2 assay. N-Nitrosopyrrolidine (NPYR) and N-nitrosodimethylamine (NDMA) incubated with formamidopyrimidine-DNA glycosylase (Fpg), caused a significant increase in oxidative DNA damage in comparison to the solvent control, the lowest effective concentrations, being 5 and 27 mM, respectively. NPYR exerted greater genotoxic effects than NDMA. None of the organosulfur compounds (OSCs) concentrations tested in presence or absence of Fpg enzyme, caused DNA damage per se. OSCs (diallyl sulfide, DAS and dipropyl sulfide, DPS, 1-50 microM; diallyl disulfide, DADS and dipropyl disulfide, DPDS, 1-5 microM) reduced the genotoxic effects of the N-nitrosamines in a dose-dependent manner when HepG2 cells were simultaneously treated with OSCs and N-nitrosamines. The effect of NPYR was attenuated by about 61-67%, respectively, with the highest concentration of DAS (50 microM) and DADS (5 microM). The protective effect of DADS (5 microM, 66%) was higher than DAS (50 microM, 53%) towards NDMA-induced oxidative DNA damage. A concentration of 50 microM DPS and 5 microM DPDS led to a 65-63% and 59-65% reduction in NPYR/NDMA-induced oxidative DNA damage, respectively. Our results indicate that OSCs protect human-derived cells against the oxidative DNA damaging effect of NPYR and NDMA, two carcinogenic compounds which occur in the environment.

Effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced oxidative DNA damage (strand breaks and oxidized purines/pyrimidines) in human hepatoma cells

The aim of this study was to evaluate the effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced DNA damage (DNA strand breaks and oxidized purines/pyrimidines) in human hepatoma cells (HepG2), using the Comet assay. Treatment with hydrogen peroxide (H(2)O(2)) increased the levels of DNA strand breaks and oxidized purine and pyrimidine bases, in a concentration and time dependent manner. Organosulfur compounds (OSCs) reduced DNA strand breaks induced by H(2)O(2). In addition, OSCs also decreased the levels of oxidized pyrimidines. However, none of the OSCs tested reduced the levels of oxidized purines. Isothiocyanates compounds (ITCs) and vitamin C showed protective effects towards H(2)O(2)-induced DNA strand breaks and oxidized purine and pyrimidine bases. The results indicate that removal of oxidized purine and pyrimidine bases by ITCs was more efficient than by OSCs and vitamin C. Our findings suggest that OSCs, ITCs and vitamin C could exert their protective effects towards H(2)O(2)-induced DNA strand breaks and oxidative DNA damage by the free radical-scavenging efficiency of these compounds.