The effects of aminoguanidine on the glycation (non-enzymic glycosylation) of lens proteins.

Aminoguanidine is being studied as a possible drug to prevent diabetic complications, by blocking the reactive carbonyl group of the Amadori product formed by glycation (non-enzymic glycosylation) of proteins. Thus it prevents the later browning and cross-linking steps. In the present work we show that labelled aminoguanidine becomes bound to glycated lens proteins. We also show that aminoguanidine inhibits the first steps of glycation of lens proteins but has no effect on carbamylation, the reaction with cyanate. It appears, therefore, that aminoguanidine can prevent glycation as well as the browning reactions, and may do so not by acting on the proteins, as other putative anti-cataract drugs do, but by decreasing the concentration of the active aldehyde form of the sugars.