摘要：In the present study,cytotoxic effects of D-Ala,D-Pro and D-Lys are demonstrated.In an effort to study the possible mechanisms of the observed cytotoxicity,catalase activity,H2O2 generation,and apoptotic activity were measured in HeLa and MCF-7 cell lines.Although D-Lys is a poor substrate for DAO and therefore low H2O2 was detected,it was shown to provoke severe impairment of cellular integrity and survival.Interestingly,a very good substrate for DAO,such as D-Pro,did not substantially reduce cell viability.On the other hand,a moderate substrate for DAO,represented by D-Ala,was shown to moderately trigger toxicity in the tested cell lines.Although a correlation between the in vitro cytotoxicity of D-amino acids and the amount of H2O2 produced was absent,there was a good agreement between the ability of D-amino acids to trigger apoptosis and to provoke toxicity.Our results indicate that the toxicity of D-amino acids does not appear to be solely mediated by H2O2.Therefore,we hypothesize that other possible contributing apoptosis-mediated pathways might cause the observed toxicity.
