Ginnalins and Maplexins from Maple Species Inhibit the Formation of Advanced Glycation Endproducts

Abstract

Glycation is a non‐enzymatic process leading to the formation of Advanced Glycation Endproducts (AGEs). The accumulation of AGEs in vivo plays an important role in the pathology of complications in diabetes. Inhibitors of AGEs, especially polyphenols from plant sources, have shown immense potential for diabetes mellitus management. In this study we evaluated the anti‐glycative effects of a series of maple gallotannins, namely ginnalins A‐C and maplexins F and J, at individual stages of protein glycation. A combination of analytical methods were used to determine AGE formation in various in vitro model systems. In the BSA‐fructose assay, maplexin F was the most potent inhibitor of AGEs formation with an IC50 value of 15.8 µM. MALDI‐TOF analysis showed that all maple gallotannins prevented the production of Amadori products, an intermediate formed in the early stage of glycation. Moreover, maple gallotannins were effective in preventing the formation of protein cross‐linking structures. Lastly, the CD spectroscopy demonstrated that the conformational changes of globular protein were reduced in the presence of maple gallotannins, suggesting that these compounds exhibited protective effect on protein's secondary structure. In conclusion, our study demonstrated that gallotannins from maple species display inhibitory activities against the formation of AGEs. Further in vivo studies are needed to evaluate the anti‐AGEs properties of maple gallotannins for their potential applications for the treatment of diabetes and related complications.