The present invention relates to compositions and methods for inhibiting nonenzymatic cross-linking (protein aging). Accordingly, a composition is disclosed which comprises a substituted 1,2,4-triazine of the formula (I) ##STR1## and the biologically and pharmaceutically acceptable salts thereof; capable of inhibiting the formation of advanced glycosylation endproducts of target proteins. The method comprises contacting the target protein with the composition. Both industrial and therapeutic applications for the invention are envisioned, as food spoilage and animal protein aging can be treated.