Biocatalytic synthesis and characterization of sn-1/3 and sn-2 monoacylglycerols.

To investigate the lipase-catalyzed synthesis of high purity sn-1/3 and sn-2 monoacylglycerols (1/3-MAG and 2-MAG) of different fatty acids (FAs). The 1/3-MAGs of three FAs (16:0, 17:0, 16:1) were synthesized using lipase-catalyzed esterification of glycerol with FAs. The 2-MAGs were obtained from the ethanolysis of synthetic triacylglycerols using sn-1,3 regiospecific lipase. The effects of lipase types, substrate ratio, temperature, reaction time and lipase load on the MAG conversion were studied. Under the optimal conditions, high purities (96.74%, 95.44%, 92.96%) with acceptable isolated yields (51.00%, 54.28%, 46.00%) were obtained for 1/3-16:0-MAG, 1/3-17:0-MAG, and 1/3-16:1-MAG, respectively. For 2-16:0-MAG, 2-17:0-MAG, and 2-16:1-MAG, the purities were 92.64, 95.04, and 96.48%, with isolated yields of 50.64, 52.16, and 26.12%, respectively. The molecular structures of the synthetic compounds were confirmed by 1H NMR, and MS and the melting points were characterized by DSC. High purity MAG isomers can be synthesized via lipase-catalyzed reactions to be building blocks for production of functional lipids, the melting points of which are largely governed by the hydrophobic interactions among the alkanyl chains.