Studies of the toxicological potential of tripeptides (L-valyl-L-prolyl-L-proline and L-isoleucyl-L-prolyl-L-proline): VIII. Assessment of cytotoxicity and clastogenicity of tripeptides-containing casein hydrolysate and Lactobacillus helveticus-fermented milk powders in Chinese hamster lung cells.

The objective of this chromosomal aberration test was to assess the mutagenic potential of tripeptides by determining their ability to induce chromosomal aberrations in cultured Chinese hamster lung (CHL) cells. The test agents used in these experiments were (1) powdered casein hydrolysate (CH) and (2) powdered Lactobacillus helveticus-fermented milk (FM). Both test agents contain two tripeptides, L-valyl-L-prolyl-L-proline (VPP) and L-isoleucyl-L-prolyl-L-proline (IPP). CHL cells were cultured and exposed in the presence or absence of a rat hepatic metabolizing system (S9); CH or FM (1250, 2500, 5000 microg/ml of incubation medium); or positive-control agents, mitomycin C (0.1 or 0.05 microg/ml) or benzo(a)pyrene (20 microg/ml). In experiments with CH, cells were incubated for 6 h (either in the presence or absence of S9) or for 24 h (without S9). In experiments with FM, the cells were incubated for 6 h (either in the presence or absence of S9) or for 24 or 48 h (without S9). Neither short-term nor continuous exposure to either CH or FM caused the induction of significant changes in cell growth indices, incidences of chromosomal aberrations or the incidence of polyploids. Exposures of cells to mitomycin C and benzo(a)pyrene consistently resulted in the induction of the anticipated aberrant cells after either short-term or continuous exposures. The results of these assays support the conclusions that, under the conditions of these experiments, neither CH nor FM possesses demonstrable potential for the induction of cytotoxicity or clastogenesis.