Lipase catalyzed acetylation of 3,5,4′-trihydroxystilbene: optimization and kinetics study

Abstract

The use of immobilized lipase from Candida antarctica (Novozym(®) 435) to catalyze acetylation of trans-3,5,4'-trihydroxystilbene was investigated in this study. Response surface methodology and 5-level-4-factor central composite rotatable design were adopted to evaluate the effects of synthesis variables, including reaction time (24-72 h), temperature (25-65 °C), substrate molar ratio (1:15-1:75), and enzyme amount (600-3,000 PLU) on the percentage molar conversion of trans-4'-O-acetyl-3,5-dihydroxystilbene. The results showed that reaction temperature and enzyme amount were the most important parameters on percentage molar conversion. Based on ridge max analysis, the optimum conditions for synthesis were: reaction time 60 h, reaction temperature 64 °C, substrate molar ratio 1:56 and enzyme amount 2,293 PLU. The molar conversion of actual experimental values was 95% under optimal conditions. The synthesis product was analyzed using HPLC, mass and NMR. The results revealed that the major product was trans-4'-O-acetyl-3,5-dihydroxystilbene. The reaction kinetics was found to follow the Ping-Pong mechanism; substrate inhibition was not found at high vinyl acetate concentration.