Antioxidant properties and efficient enzymatic synthesis of lipophilic resveratrol monolaurates

Resveratrol (RES) is a natural non-flavonoid polyphenolic antioxidant. The low solubility of RES in water (26 mg/L) and oil (175.51 mg/kg) limited its antioxidant activity and bioavailability. In order to overcome these issues, in this work, a lipophilic resveratrol laurate was efficiently synthesized using RES as starting material in the presence of enzymes. The catalytic activities of enzymes (Lipase CALA, Lipozyme TL 100L, Lipase CALB, Novozym 435, Lipozyme TLIM, and Lipozyme RMIM) were investigated and screened. Moreover, reaction conditions were optimized using response surface methodology. Meanwhile, thermodynamic and kinetic analyses were also conducted to investigate the enzymatic mechanism. Results showed that, Lipozyme RMIM showed the best performance for resveratrol monolaurates regioselective synthesis. Two products, 3-resveratrol monolaurate (3-RC12) and 4′-RC12, were prepared and purified. The optimal reaction conditions for the preparation of 3-RC12, and 4′-RC12 were 1:65 substrate ratio and 11.7 wt% lipase dosage at 75 °C for 33.2 h. Under these conditions, the RES conversion reached a maximum of 98.04 ± 1.76%. The regioselective products were analyzed for antioxidant activity. Notably, the esterification site significantly impacts resveratrol monoesters' antioxidant activity. And 3-RC12 demonstrates superior ABTS and DPPH radical cation scavenging activity, surpassing RES and 4′-RC12. Notably, in yield and antioxidant activity, 3-RC12 is better than 4′-RC12, which make it a potential antioxidant for industrial application.