Inhibitory effect of caffeic acid and dihydrocaffeic acid on the formation of advanced glycation end products: Mechanism analysis based on intermolecular interaction

The accumulation of advanced glycation end products (AGEs) generated from glycation reaction accelerates the development and deterioration of some diseases. Herein, the AGEs model of fructose-induced glycation of human serum albumin (HSA) was constructed and characterized. Both caffeic acid (CA) and dihydrocaffeic acid (DHCA) can inhibit the formation of AGEs, and the inhibitory effect of CA was more pronounced, as confirmed by fluorescence spectroscopy, gel electrophoresis, scanning electron microscopy, and carbonyl and thiol contents analysis. The binding of CA and DHCA to HSA was investigated by fluorescence spectroscopy and molecular docking. The primary inhibitory mechanism was the occupation of the glycation site LYS199 of HSA, and the more significant inhibitory effect of CA was related to its stronger binding affinity. Furthermore, the conformational changes caused by glycation and CA/DHCA binding were monitored using fluorescence, circular dichroism, and dynamic light scattering analysis. The results would help to elucidate the inhibitory mechanism of CA and DHCA on AGEs formation based on their different structures and inhibitory effects, and provide guidance for choosing natural inhibitors for diabetes.