Carica papaya lipase-catalyzed synthesis of terpene esters

Abstract

An efficient approach to synthesize terpene esters using plant lipase-Carica papaya lipase (CPL) as the biocatalyst was developed in this work. The effects of chain length of acyl donor and solvent type on the CPL-catalyzed transesterification reaction were investigated firstly. It was found that CPL showed the highest activity in n-hexane with vinyl octanoate as the best acyl donor. To obtain high yield of terpene esters, the main reaction parameters were studied and further optimized by response surface methodology. Ping–Pong Bi–Bi mechanism with dead end complex of citronellol was found to fit the initial rate data and the kinetic parameters were obtained by regression analysis. The optimal conditions were: 55 °C, 9% (w/w) of CPL based on substrate, equimolar ratio of substrates. Under these conditions, yield of more than 99% was achieved after 8 h reaction. Ionic liquids (ILs) were used to improve the operational stability because the CPL was found to lose its activity markedly during the repeated runs, it showed that the stability of CPL increased about 5 times when it was coated with ionic liquids. The CPL is low cost yet effective, thus the process developed here shows obvious potential for the production of terpene esters industrially.