The inhibition of oleanolic acid on protein non-enzymatic glycation

Non-enzymatic glycation can produce advanced glycation end products (AGEs), inducing a series of diabetic complications. In this study, oleanolic acid (OA) was found to inhibit the formation of fructosamine and α-dicarbonyl compounds, while AGEs was almost suppressed by OA at the concentration of 500 μg/mL. Moreover, OA exhibited strong anti-fibrillation and antioxidant abilities. It decreased the production of dityrosine, N′- formylkynurenine and kynurenine with strong ·OH and O2·− scavenging capacities. The binding of OA with lysine and arginine of bovine serum albumin (BSA) prevented BSA from the attack of sugars. The C−12 in the C ring of OA was predicted to trap methylglyoxal (MGO), forming the OA−MGO adduct. The antioxidant and MGO trapping abilities together with the secondary structure protection may be the main mechanism of anti-glycation ability of OA. These findings suggest that foods rich in OA are promising sources of anti-glycation agents. The study also provides a theoretical basis for the further functional research of OA in the prevention and treatment of diabetic complications.