Inhibitory effect of epicatechin gallate on protein glycation

Protein glycation can produce the advanced glycation end products (AGEs), which has a potential health risk due to its relevance with diabetic complications. Searching for potent inhibitors to suppress hyperglycemia-induced protein glycation is of great significance. Here, we probed the anti-glycation potential of epicatechin gallate (ECG), an important ingredient of green tea, by spectroscopy and chromatography supplemented by molecular docking. It was found that ECG suppressed the carbonylation and the formation of amyloid cross-β structures of bovine serum albumin (BSA) as well as the generation of AGEs in BSA-fructose model by 65.6%, 73.7% and 87.0%, resepctively. A combination of ECG with epigallocatechin gallate (EGCG) at molar ratios from 0.5:1 to 2:1 exhibited the interactive effects on AGEs formation from moderate antagonism to synergy. Moreover, ECG at 44.2 μg/mL showed a trapping efficiency of 81.6% for the important precursor methylglyoxal (MGO) of AGEs within 24 h, and the formed ECG-mono-MGO and ECG-di-MGO adducts were verified by LC-QqQ-MS analysis. The inhibitory effect of ECG on the protein glycation may be due to its MGO trapping and the specific binding with certain amino acid residues of BSA. These findings may provide the theoretical basis for the development of ECG as an inhibitor of protein glycation.