Inhibition of nonenzymatic protein glycation and lipid peroxidation by drugs with antioxidant activity

We studied the effects of aminoguanidine (AG), beta-resorcylidene aminoguan idine (RAG), DL-penicillamine (PNCA) and captopril on early and advanced gl ycation of human serum albumin (HSA). We also assessed inhibition of lipid peroxidation by AG and RAG in erythrocytes. Incubation of HSA with D-glucos e (20 mM, 37 degrees C for 21 days) led to the formation of Amadori product s and fluorescent advanced glycation end-products (AGE). Only PNCA markedly reduced the formation of Amadori products, while all tested compounds mark edly reduced the formation of AGE. AG and RAG also inhibited malondialdehyd e formation in erythrocytes incubated with hydrogen peroxide. Addition of A G at concentrations from 1 mu M to 1mM caused a 10-80 % inhibition of lipid peroxidation. Thus, AG and RAG inhibit toxic oxidative processes and may h ave therapeutic potential in a number of human diseases.