Ultrasonic pretreatment for lipase-catalyzed synthesis of 4-methoxy cinnamoyl glycerol

Abstract

• Ultrasonic pretreatment lipase-catalyzed synthesis of 4-methoxy cinnamoyl glycerol (4MCG) was studied. • The enzymatic method using ultrasonic pretreatment significantly improved overall esterification reaction rate and monoester (4MCG) yield. • The ultrasonic pretreatment process did not damage the lipase activity. 4-Methoxy cinnamoyl glycerol (4MCG) is a very promising UV filters material in personal care products. In order to effectively improve the yield of 4MCG, a systematic study on ultrasonic pretreatment enzymatic esterification for 4MCG products was carried out. An ultrasonic frequency of 35 kHz, ultrasonic power of 150 W and ultrasound irradiation time of 1.5 h was determined to guarantee satisfactory degree of esterification and lipase activity. The optimum production was achieved in organic solvent system at 65 °C with 4MCA to glycerol molar ratio of 1:5, enzyme amount of 15 mg/mL, resulting in a monoester yield of above 66% and 55% after 48 h and 24 h of reaction under ultrasonic pretreatment, respectively. The experimental kinetic data were studied. The reactions were modeled by a system of sequential first-order rate expressions, kinetic parameters were estimated from experimental data fit to the model equations. Results show that the monoester yield in the ultrasonic pretreatment process (24 h) were above 1.5-fold as that in mechanical stirring process without essential damaging to lipase activity. The enzymatic method using ultrasonic pretreatment was obviously superior to the mechanical stirring for enzymatic method and chemical method in terms of conversion rate and the monoester yield. These results are of great significance for applying ultrasonic pretreatment method to prepare 4MCG.