Improved enzymatic synthesis route for highly purified diacid 1,3-diacylglycerols

Abstract

The nutritional benefits and biological functions of diacylglycerols (DAGs) have attracted much attention regarding their synthesis. In this study, we improved the synthesis of diacid 1,3-DAGs by the enzymatic transesterification of 1-monoolein with a fatty acid vinyl ester as an acyl donor. First, 1-monoolein was prepared in 95% ethanol with Amberlyst resin as a catalyst by the cleavage of 1,2-acetonide-3-oleoylglycerol, which had been synthesized by enzymatic esterification of 1,2-acetonide glycerol with oleic acid. Second, purified 1-monoolein was reacted with vinyl palmitate in the presence of a lipase to obtain 1-oleoyl-3-palmitoylglycerol. Subsequently, the reaction conditions for the synthesis of diacid 1,3-DAGs were evaluated. Under the selected conditions, the crude mixture contained 90.6% pure 1-oleoyl-3-palmitoylglycerol. After purification by two-step crystallization, pure 1-oleoyl-3-palmitoylglycerol was obtained with a yield of 83.6%. The main innovations were the use of enzymatic transesterification to obtain highly purified diacid 1,3-DAGs instead of using chemical synthesis and the use of an irreversible reaction with a fatty acid vinyl ester as acyl donor rather than reversible reactions.