Inhibitory Mechanism of Tryptophan on the Formation of Advanced Glycation End Products in Vitro

The intake of dietary advanced glycation end products (AGEs) is closely related to a variety of chronic diseases, especially diabetes and kidney disease. In this study, 13 amino acids were screened for their inhibitory activity on AGEs, revealing that tryptophan (Trp) was selected to evaluate its mechanism of action against the formation of AGEs in bovine serum albumin (BSA)-fructose, BSA-methylglyoxal (MGO), BSA-glyoxal (GO) and arginine (Arg)-MGO models. The inhibitory effect of Trp on fluorescent AGEs was concentration dependent. In BSA-MGO model, the inhibitory effect of Trp on the formation of AGEs was the best, followed by BSA-GO and Arg-MGO models, and Trp had little effect on BSA-fructose mode. The inhibition of different concentrations of Trp on N^ε-carboxymethyl lysine (CML) and N^ε-carboxyethyl lysine (CEL) showed a bell-shaped curve with the highest inhibition efficiency being observed at 1000 μg/mL concentration. Moreover, it was found that Trp could capture MGO by aromatic electron affinity substitution and the Pictet Spengler reaction, with a maximum trapping capacity of 3 molars.