Towards Understanding the Liver Toxicity Observed for Herbal Products of Withania somnifera Ashwagandha DNA Damage by Withanone

Abstract

we decided to look into the various metabolites of Ashwagandha. A structural analysis of the various metabolites revealed that withanolites have multiple electrophilic functional groups (epoxide and Michael acceptor) that are generally associated with adverse reactions and are called toxicophores. We first looked into the toxicology of win, being a major withanolite metabolite that has an epoxide functional group and Michael acceptors (alkene) in its structure. We found that win forms adducts with nucleosides, dG, dA, and dC but not dT. Using various biochemical assays, we showed that win forms non-labile adducts in DNA. We also found that win forms adducts with the cellular protective agent GSH and with amines, although the aminde-adducts are reversible. Interestingly, win can alkylate DNA in the presence of GS and amines indicating the potential genotoxicity of this metabolite. They found that the DNA adducts of win have serious biological consequences. We also showed using mammalian cell survival assays, that win is non-toxic till ~25 uM, with cytotoxicity gradually increasing with increasing concentrations of win above that. Finally, based on the data presented here we concluded that win is efficiently detoxified by GSH under normal cellular conditions, but under limiting GSH concentration or high concentration (overdose) of win it can be cytotoxic. Our work provides a potential mechanism for the reported Ashwagandha-mediated liver damage.