Synthesis of alkyl glycoside fatty acid esters: Effect of reaction parameters and the incorporation of n-3 polyunsaturated fatty acids

Abstract

Alkyl glycoside fatty acid esters were synthesized by lipase-catalyzed transesterification of methyl glucoside, methyl galactoside, and octyl glucoside as the carbohydrate starting material and methyl oleate, eicosapentaenoic acid, and docosahexaenoic acid as the acyl donors. The experiments were carried out in benzene/pyridine using lipases from various sources as biocatalysts. The parameters studied were the effects of different enzymes, enzyme concentration, enzyme reuse, solvent volume, and different alkyl glycosides on the incorporation of oleic acid (n-9) and n-3 polyunsaturated fatty acids into alkyl glycosides. The immobilized Candida lipases SP382 and 2001 gave higher incorporation of fatty acids (44–75 mol%) compared to the immobilized Mucor miehei (18 mol%) and the other nonimmobilized lipases (0–37 mol%). For the different carbohydrates, methyl glucoside gave the highest incorporation of oleic acid (76.5 mol%) followed by methyl galactoside (71.5 mol%) and octyl glucoside (53.7 mol%). The optimal conditions for these reactions under the conditions studied were immobilized SP382 lipase from Candida antarctica as enzyme used at 20%, once, in 3 ml of benzene/pyridine (2:1 v/v), with methyl glucoside as the carbohydrate starting material and ethyldocosahexaenoic acid as the acyl donor.