Reactive metabolites

One of the reasons behind unexpected drug induced toxicity can be chemically reactive metabolites that bind covalently to protein or DNA. Due to their high reactivity and short life-span, these metabolites cannot be analyzed directly as such, but have to be first stabilized by trapping agents, such as S-glutathione (GSH), cyanide (KCN) or semicarbazide (SCA). Of these, GSH is clearly the most used trapping agent, although KCN and SCA may be used for trapping certain types of reactive metabolites that are not trapped by GSH, such as iminium ions or aldehydes. In addition, acyl-glucuronide conjugates, formed in the presence of carboxylic acid group, may cause toxicity by covalent binding to proteins. Liability for toxicity of an acyl glucuronide metabolite may be evaluated by measuring the rate of acyl-migration, i.e., formation of isomeric acyl-glucuronides and eventually formation of reactive aldehyde-isomer. This method is a valuable tool for assessing acyl-glucuronide reactivity without the need for synthetised glucuronide metabolites. In addition to acyl glucuronide conjugates, also formation of even more reactive Acyl CoA-conjugates or other related conjugates (glycine, taurine, carnitine) may be investigated by our methods.