Modeling and optimization of lipase-catalyzed hydrolysis for production of (S)-2-phenylbutyric acid enhanced by hydroxyethyl-β-cyclodextrin

Abstract

Abstract An efficient reactive system was established to produce (S)-2-phenylbutyric acid (2-PBA) through the enzymatic enantioselective hydrolysis of 2-phenylbutyrate ester (2-PBAE) in aqueous medium. Lipase CALA from Canadian antarctica and hexyl 2-phenylbutyrate (2-PBAHE) were identified upon screening as the best enzyme and substrate, respectively. Adding hydroxyethyl-β-cyclodextrin (HE-β-CD) to improve the solubility of the substrate resulted in a 1.5 times increase in substrate conversion while retaining a high enantioselectivity compared with that when HE-β-CD was not added. The effects of lipase concentration, substrate concentration and HE-β-CD concentration, temperature, pH, and reaction time on enantiomeric excess and conversion rate were investigated, and the optimal conditions were identified using response surface methodology (RSM). Under the optimal conditions, namely 50 mg/mL lipase CALA, 30 mmol/L substrate, 60 mmol/L HE-β-CD, pH of 6.5, temperature of 83 °C and reaction time of 18 h, the enantiomeric excess and overall conversion rate were 96.05% and 27.28%, respectively. This work provides an efficient alternative method for improving the conversion of aromatic ester substrates by including β-cyclodextrin in an aqueous hydrolysis reaction system.