Dietlind Adlercreutz

Chemo-enzymatic epoxidation of oleic acid and methyl oleate in solvent-free medium

Chemo-enzymatic epoxidation of oleic acid (OA) and its methyl ester has been performed using hydrogen peroxide and immobilized lipase from Candida antarctica (Novozym® 435). The purpose of the study was to characterize the reaction under solvent-free conditions. The reaction temperature had a significant impact on epoxidation of OA. At lower temperatures, the substrate conversion was hindered by the formation of solid epoxystearic acid product. Nearly 90% conversion of OA to the epoxide product was obtained after 6 h at 50°C. Longer reaction times at 40°C and above resulted in by-product formation and eventually lowered the product yield. In contrast, the reaction with methyl oleate (MO) was less influenced by temperature. Almost complete epoxidation was achieved at 40–60°C; the higher the temperature the shorter was the reaction time. The main epoxidation product obtained was epoxystearic acid methyl ester (EME), and the remaining was epoxystearic acid (EA) formed by the hydrolytic action of the lipase. Recycling of the lipase for epoxidation of MO at 50°C indicated that the immobilized enzyme was prone to activity loss.

Enzymatic conversions of polar lipids. Principles, problems and solutions

This text provides a brief overview of the principles of enzymatic lipid conversion and some recent advances in the enzymatic conversion of glycerophospholipids and galactolipids. Lipases and phospholipases are used to exchange fatty acids or the polar group in the lipids. The reactions can be carried out either as hydrolysis-esterification sequences or as one-step transferase reactions. The scope and limitations of the different methods are discussed.