Carnosine and anserine act as effective transglycating agents in decomposition of aldose-derived Schiff bases

There are numerous publications describing the positive effects of carnosine (β-alanyl-histidine) and anserine (β-alanyl-1-N-methyl-histidine) on cell and organ function. Of special interest to us is the fact that these dipeptides act to retard and (in one instance) reverse non-enzymatic glycation. To date, the primary explanation for these anti-glycating effects has been the fact that carnosine and anserine can serve as alternative and competitive glycation targets, thereby protecting proteins from this deleterious process. In this paper, we document another mechanism by which these two peptides can retard or reverse glycation. The process involves decomposition of the very first intermediates of the non-enzymatic glycation cascade (aldosamines a.k.a. Schiff bases) by nucleophilic attack of carnosine and/or anserine on the preformed aldosamine such as glucosyl-lysine. If future research shows this reaction is to be physiologically important, this mechanism could explain some of the beneficial effects of carnosine and anserine as anti-glycating agents.