Genotoxicity evaluation of two derived products from Allium extracts: s-propylmercaptocysteine and s-propyl mercaptoglutathione

Propyl-propane-thiosulfonate (PTSO) is one of the main organosulfur compounds present in Allium essential oils with a widely documented biological activity. For this reason, it could be used as a food and feed additive in the agri-food industry. A genotoxicity evaluation of substances and their metabolites present in food is necessary to guarantee the consumer's health following the recommendations of the European Food Safety Authority (EFSA). To evaluate the toxicological profile of derivatives of PTSO, the cytotoxicity, an Ames test, a micronucleus test and the comet assay were performed. Results showed that non-cytotoxic effects were observed in Caco-2 exposed to s-propyl mercaptocysteine (CSSP) and s-propyl mercaptoglutathione (GSSP) (0-450 mu M). The mutagenicity index remained in the range of 0.6-1.4 for both compounds, showing no mutagenic effects for the concentrations of 5000-312.5 mu g GSSP/plate and 250-15.63 mu g CSSP/plate. Moreover, the % binucleated cells with micronuclei were 1.3-2.2 and 1.6-2.7 for GSSP and GSSP, respectively. For comet assays there was no DNA-genotoxic or oxidative damage in a concentration range of 112.5-450 mu M. Therefore, we can conclude that these compounds are not genotoxic at the conditions tested. These results support that the presence of CSSP and GSSP in the food/ feed is not of concern, although further studies are needed to complete their safety profile.