Studies On The Lipase-catalyzed Esterification Of Oleyl Ferulate

Ferulic acid (FA) is widely used in food, pharmaceutical and cosmetic areas, due to its antioxidant and anticancer activity. However, the hydrophilic character of ferulic acid reduces its application in hydrophobic media. Combination of ferulic acid with lipophilic moieties, can be employed to alter its solubility in oil-based solvent. In the present study, the esterification conditions between ferulic acid and oleyl alchol were investigated in non-aqueous medium, catalyzed by the native Aspergillus niger lipase and the Novozym 435 of Denmark. The results were as follows:The result indicated that the esterification conversion reached to 99.2%, when the reaction was carried out in isooctane(single organic solvent), Aspergillus niger lipase concentration was 0.1 g/mL, the temperature was 60℃, molecular sieve concentration was 5 mg/mL, and the molar ratio of ferulic acid to oleyl alchol was 1:6.In the isooctane/2-butanone system(co-solvents), under the following reaction conditions:Aspergillus niger lipase concentration 0.2 g/mL, the temperature 60℃, molecular sieve concentration 5 mg/mL and the molar ratio of ferulic acid to oleyl alchol 1:8,conversion rate of esterification was 97.6%;the optimal conditions in the cyclohexane/2-butanone system(co-solvents) were Aspergillus niger lipase concentration 0.25 g/mL, the temperature 60℃,molecular sieve concentration 5 mg/mL and the molar ratio of ferulic acid to oleyl alchol 1:8,conversion rate of esterification was 91%.Volumetric productivity of oleyl ferulate in isooctane/[Hmim][PF6](3:1,V/V)(organic solvent/ionic liquid) mixing system was 13.1 mg/mL, when ferulic acid content was 0.05 mmol/mL, the molar ratio of ferulic acid to oleyl alchol was 1:8,catalyzed by 0.375 g/mL Aspergillus niger lipase under 60℃.The result indicated that the volumetric productivity of oleyl ferulate reached to 4.51 mg/mL, when the reaction was carried out in [Hmim][PF6] system (pure ionic liquid), Aspergillus niger lipase concentration was 0.267 g/mL, the temperature was 60℃,ferulic acid content was 0.08 mmol/mL.In the isooctane/[Hmim][PF6](3:1,V/V)(organic solvent/ionic liquid) mixing system, under the following reaction conditions:Novozym 435 concentration 75 mg/mL, ferulic acid content 0.08 mmol/mL, the temperature 60℃and the molar ratio of ferulic acid to oleyl alchol 1:4, volumetric productivity of oleyl ferulate was 48.5 mg/mL; the optimal conditions in the isooctane/[Omim][PF6](3:1,V/V)(organic solvent/ionic liquid) mixing system were Novozym 435 concentration 75 mg/mL, ferulic acid content 0.05 mmol/mL, the temperature 60℃and the molar ratio of ferulic acid to oleyl alchol 1:4, volumetric productivity of oleyl ferulate was 26.92 mg/mL.In [Bmim][TF2N] (pure ionic liquid) system, volumetric productivity of oleyl ferulate was 105.7 mg/mL, under the following conditions:200 rpm speeds of shaking, temperature 60℃, Novozym 435 content 160 mg/mL; in [Bmim][PF6](pure ionic liquid) system, when speeds of shaking was 200 rpm, the temperature was 60℃, Novozym 435 content was 200 mg/mL, volumetric productivity of oleyl ferulate was 130.6 mg/mL.