Hydrolysis and esterification of acylglycerols and analogs in aqueous medium catalyzed by microbial lipases

The stereoselectivity of microbial lipases from Chromobacterium viscosum (CVL) and Rhizopus arrhizus (RAL) towards monoacylglycerols (rac-1(3)-oleoylglycerol and 2-oleoylglycerol), diacylglycerols (1,3-dioleoylglycerol and rac-1,2(2,3)-dioleoylglycerol) and 2-O-ether analogs (rac-1(3)-oleoyl-2-O-hexadecylglycerol and rac-1(3)-octanoyl-2-O-hexadecylglycerol) was determined. The results of the hydrolysis of 2-O-ether analogs confirmed the importance of the substituent at C-2 of acylglycerols in the stereoselective recognition by microbial lipases and also showed that acylation of mono- and diradylglycerols with oleic acid overlaps the hydrolysis reaction in aqueous medium. With the short-chain, water-soluble octanoic acid no significant esterification occurred. Using rac-1,2(2,3)-dioleoylglycerol as a substrate for the hydrolysis with RAL and CVL, the appearance of 1,3-dioleoylglycerol and of 1(3)-monooleoylglycerol was demonstrated. The possibility of chemical vs. enzyme-catalyzed isomerization of 1,2-dioleoylglycerol and of 2-oleoylglycerol is discussed.