Inhibition of glycoxidative modification of proteins by some substances of natural origin

Abstract

Summary Introduction: Advanced glycation end-products (AGE) and advanced oxidation protein products (AOPP) are the main products of glycoxidative modification in diabetes. Objective: The aim of this study was to identify the natural substance with the strongest antiglycoxidative properties among dietary supplements or medicines available without prescription in Poland. Methods: Bovine serum albumin (BSA), vitamin C (VC), aminoguanidine (A), quercetin (Q) and green tea (GT) were tested in vitro in comparison to controls in glycation, oxidation and glycoxidation processes. The decreased AGE and AOPP concentrations were measured as markers of these processes. Results: AGE level was reduced by 72% by VC and at least by 43% by all examined substances in the glycation process. AOPP was reduced by 99% by VC and at least by 40% by all examined substances in the oxidation process. Formation of AGE/AOPP was inhibited by 61% by Q and by 97% by A, and at least 49/88% by all examined substances, respectively. This lowering of AGE/AOPP level was statistically significant (p<0.001) for all test substances in comparison to the positive control C(+). Conclusion: All examined substances are able to inhibit glycative, oxidative and glycoxidative modification of proteins in different degrees depending on their concentration.