Position-Selective Synthesis of MAG Isomers: Enzymatic Approaches and Applications

Monoacylglycerols (MAG) are manufactured as surfactants for cosmetic and food applications. MAGs of medium-chain FAs are beneficial in terms of their dual surfactant and antimicrobial properties. Commercial MAGs mainly comprise saturated FAs, with oleic acid as the only unsaturated option. While MAGs of other unsaturated FAs are expected as functional surfactants, enzymatic methods are preferred for producing oxidation-sensitive unsaturated FA MAGs.

MAGs exist as two isomers (1-MAG and 2-MAG) based on FA binding position on glycerol. Our research revealed enhanced position selectivity in lipase-catalyzed MAG synthesis under dehydration conditions. The strategies in synthesis are:
1- MAG Synthesis: Esterification of FAs with glycerol using MAG/DAG lipase from Penicillium camembertii under reduced pressure selectively produces 1-MAG by suppressing DAG formation. This method successfully synthesizes various MAGs of saturated and unsaturated FAs from C6 to DHA, except C7 and 8.
2-MAG Synthesis: Produced by exchanging FAs at TAG's 1(3) position using Rhizomucor miehei or Candida antarctica lipases to ethyl esters. R. miehei lipase requires 5% water in ethanol, while water inhibits C. antarctica lipase's transesterification activity. The lack of FA specificity of CALB enables 2-MAG production from various TAG including milk fat and fish oils with short chain FAs and PUFAs. This reaction is used in Joint JOCS/AOCS Official Method Ch 3a-19 for FA distribution analysis in TAGs. Additionally, 2-MAG serves as a building block for structured lipids, successfully creating cetacean milk fat mimics with 16:0 at 2-position and PUFAs at 1(3)-position. The structured lipid could be beneficial for human use.