Lipase-catalyzed Esterification of Selected Phenolic Acids with Linolenyl Alcohols in Organic Solvent Media

Lipase-catalyzed esterification of selected phenolic acids with linolenyl alcohols was investigated in selected organic solvent media. The enzyme activity for the esterification of dihydrocaffeic acid with linolenyl alcohol in solvent mixtures of hexane/2-butanone of 75:25 (v/v) and 65:35 (v/v) was 0.88 and 0.47 micromol of esterified dihydrocaffeic acid/(g of solid enzyme.min), respectively, with a corresponding esterification yield of 76 and 58%, respectively. However, the esterification of ferulic acid with linolenyl alcohol in the reaction medium of hexane/2-butanone of 65:35 (v/v) resulted in a low yield (16%). Using the reaction medium of hexane/2-butanone of 75:25 (v/v), an increase in linolenyl alcohol concentration with a concomitant use of a constant amount of dihydrocaffeic acid resulted in an increase in esterification yield. The highest esterification yield of 99% was obtained with a ratio of dihydrocaffeic acid to linolenyl alcohol of 1:8 after 7 d of reaction. Biosynthesis of the end product, linolenyl dihydrocaffeate, was confirmed by electrospray ionization mass spectroscopy structural analysis; the ester product demonstrated an antiradical activity close to that of alpha-tocopherol.