Production of glycidyl ethers by chemo-enzymatic epoxidation of allyl ethers

Production of glycidyl ethers is industrially carried Out by reacting alcohols with epichlorhydrin, a potentially carcinogenic compound. This paper investigates a less hazardous alternative-that of a chemo-enzymatic process in which Candida antarctica lipase B catalysed generation of peracid from a carboxylic acid is followed by a Prileshajev epoxidation of the corresponding allyl ether. Trimethylolpropane monoallyl ether (TMPME) was used as a model substrate. A maximal epoxide product yield of 77% was achieved through the optimization of temperature. acid concentration and hydrogen peroxide concentration. Peracid formation was considerably faster than the subsequent epoxidation step, and accumulation of the peracid was Found to be important to drive the epoxidation forward. (C) 2008 Elsevier B.V. All rights reserved

Enzymatic Synthesis of Mixed Acid Phospholipids

Mixed acid phospholipids are valuable compounds, which are used mainly in membrane- and lipoprotein research and in liposome technology. The chemical synthesis of these special lipids is rather difficult and involves both toxic chemicals and harsh reaction conditions, which makes the products less attractive for medical and biological applications. Enzymes in contrast catalyze chemical reactions under mild conditions, providing a promising alternative to the traditional chemical approach. In the thesis 1,3 specific lipases and phospholipase A2 have been applied in order to incorporate fatty acids specifically into the sn-1 and sn-2 position respectively. The phospholipase A2-catalyzed esterification of 1-acyl lysophosphatidylcholine with oleic acid to produce phosphatidylcholine with oleic acid in the sn-2 position was studied in toluene under water activity controlled conditions. The aim of the study was to find the conditions most favorable for the synthesis reaction. To do this the impact of various reaction parameters such as water activity, substrate concentration and temperature on enzyme activity and equilibrium yield was determined. The phosphatidylcholine to lysophosphatidylcholine ratio at equilibrium increased with decreasing water activity and increasing fatty acid concentration, as can be expected from the law of mass action of an esterification reaction. The enzyme activity on the other hand decreased under conditions that favor the esterification. The best yield in the synthesis reaction was 60% at a water activity of 0.11 and an oleic acid concentration of 1.8 M. 1,3 specific lipases were employed to introduce caproic acid into the sn-1 position of phosphatidylcholine. The reaction was carried out in either one step (transesterification reaction) or in two steps (ethanolysis and re-esterification). A comparison between these two reaction modes was made with regard to product yield, product purity, reaction time, and by-product formation as a consequence of acyl migration. Esterification and transesterification reactions were studied in toluene under water activity controlled conditions. The yield in both types of reactions was the same under identical conditions. The highest yield (78%) was obtained at a water activity of 0.11 and a caproic acid concentration of 0.8 M. The reaction time was shorter in the esterification than in the transesterification reaction. The difference in reaction time was especially pronounced at low water activities and high fatty acid concentrations. The loss due to acyl migration was around 16% under a wide range of conditions. The incorporation of a fatty acid into the sn-1 position proved to be thermodynamically more favorable than the incorporation of a fatty acid into the sn-2 position. By a combination of lipase and phospholipase A2 action it was possible to convert egg yolk phosphatidylcholine, containing various fatty acids into phosphatidylcholine with capric acid in the sn-1 position and caproic acid in the sn-2 position. Two egg yolks with a weight of 16 g were required in order to obtain 160 mg of the desired product

Enzymatic fatty acid exchange in glycerophospholipids

Lipases can be used to exchange fatty acids in the sn-1 position of glycerophospholipids and phospholipase A2 is useful for the corresponding exchange reaction in the sn-2 position. In both cases, the exchange can be done in a one-step acidolysis process or in a two-step process. In the latter case, the original fatty acid in the desired position is removed by enzymatic hydrolysis or alcoholysis and after isolation of the resulting lysophospholipid, the new fatty acid is introduced, using the same enzyme, in an esterification reaction. Several synthesis examples from the literature are reviewed. Incorporation of a new fatty acid into the sn-1 position is more favourable than incorporation into the sn-2 position because of the magnitudes of the equilibrium constants of the reactions and because lipases can be used at much lower water activity than phospholipase A2. With the consecutive use of both enzymes highly pure products with defined fatty acids in both positions can be obtained

Enzymatic and chemical synthesis of phosphatidylcholine regioisomers containing eicosapentaenoic acid or docosahexaenoic acid

Regioselective incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into phosphatidylcholine (PC) was carried out using enzymatic and chemical synthesis. Incorporation at the sn-1 position was successfully achieved by lipase-catalysed esterification of 2-palmitoyl-lysophosphatidylcholine (LPC), although in most cases, the enzymes incorporated EPA and DHA at lower rates than other fatty acids. For the incorporation of DHA, Candida antarctica lipase B was the only useful enzyme, while incorporation of EPA was efficiently carried out using either this enzyme or Rhizopus arrhizus lipase. The highest yields in the lipase-catalysed reactions were obtained at the lowest water activity (close to 0). However, by carrying out the reactions at a higher water activity of 0.22, more EPA and DHA were incorporated. Esterification of 2-palmitoyl-LPC with pure EPA at this water activity converted 66 mol-% of LPC to PC using Rhizopus arrhizus lipase as catalyst. When the fatty acid was DHA and the catalyst Candida antarctica lipase B, 45 mol-% of PC was obtained. For incorporation of EPA and DHA at the sn-2 position, phospholipase A(2) was used, but the reaction was very slow. Chemical coupling of 1 -palmitoyl-LPC and EPA or DHA was more efficient, resulting in complete conversion of LPC

Characterization and optimization of phospholipase A2 catalyzed synthesis of phosphatidylcholine

The phospholipase A2 (PLA2) catalyzed synthesis and hydrolysis of phosphatidylcholine (PC) was studied in a water activity controlled organic medium. The aim of the study was to find the conditions most favorable for the synthetic reaction. To do this, the impact of various parameters such as water activity, substrate concentration and temperature on enzyme activity and equilibrium yield was determined. The PC to lysophosphatidylcholine (LPC) ratio at equilibrium increases with decreasing water activity and increasing fatty acid concentration, as can be expected from the law of mass action of an esterification reaction. The enzyme activity on the other hand decreases under conditions that favor the esterification. The best yield in the synthetic reaction is 60% at a water activity of 0.11 and an oleic acid concentration of 1.8 M. That is to our knowledge the highest yield ever reported in this reaction. Both the hydrolysis and synthesis reaction follow Michaelis-Menten kinetics, the apparent K(m) values are the same for PC and LPC, namely 4.9 mM. V(max) is 82.5 and 10.4 nmol h-1 mg-1 for the hydrolysis and synthesis reaction, respectively. Studies on PLA2 at water activity controlled conditions resulted in a more complete understanding of the enzymatic reaction and allowed to find the conditions most favorable for the synthetic reaction

Synthesis of phosphatidylcholine with defined fatty acid in the sn-1 position by lipase-catalyzed esterification and transesterification reaction.

The incorporation of caproic acid in the sn-1 position of phosphatidylcholine (PC) catalyzed by lipase from Rhizopus oryzae was investigated in a water activity-controlled organic medium. The reaction was carried out either as esterification or transesterification. A comparison between these two reaction modes was made with regard to product yield, product purity, reaction time, and byproduct formation as a consequence of acyl migration. The yield in the esterification and transesterification reaction was the same under identical conditions. The highest yield (78%) was obtained at a water activity (a(w)) of 0.11 and a caproic acid concentration of 0.8 M. The reaction time was shorter in the esterification reaction than in the transesterification reaction. The difference in reaction time was especially pronounced at low water activities and high fatty acid concentrations. The loss in yield due to acyl migration and consequent enzymatic side reactions was around 16% under a wide range of conditions. The incorporation of a fatty acid in the sn-1 position of PC proved to be thermodynamically much more favorable than the incorporation of a fatty acid in the sn-2 position

Enzymatic oil extraction and positional analysis of omega-3 fatty acids in Nile perch and salmon heads

The use of commercial proteases, bromelain and Protex 30L for oil extraction/recovery of polyunsaturated fatty acids (PUFA) from Nile perch and salmon heads was evaluated. Four phases were obtained after hydrolysis, oily phase, emulsion, aqueous phase and sludge. An increase in water content during the hydrolysis resulted in a decrease in oil yield. Maximum oil yield was obtained when hydrolysis was performed with Protex 30L at 55 C, without pH adjustment or water addition. An oil yield of 11.2% and 15.7% of wet weight was obtained from Nile perch and salmon heads, respectively, compared to 13.8% and 17.6%, respectively obtained using solvent extraction. Fatty acid distribution analysis showed 50% of palmitic acid was in sn-2 position in Nile perch triglycerides (TAG), while only 16% of this fatty acid was in sn-2 position in salmon oil TAG. (C) 2010 Elsevier Ltd. All rights reserved

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

Solvent-free enzymatic synthesis of fatty alkanolamides

An environmentally benign and volume efficient process for enzymatic production of alkanolamides is described. Immobilized Candida antarctica lipase B, Novozym (R) 435, was used to catalyze the condensation of lauric acid with monothanolamine. The raction temperature of 90 degrees C was required to keep the reactants in a liquid state. Atepwise addition of the amine minimized problems caused by the formation of a highly viscous amine/fatty acid ion pair. The enzyme was both very active and stable under the reaction conditions, with about half of the activity remaining after 2 weeks. The maximum amide yield obtained when using equimolar amounts of the r4eaction wa 75%, which could be increased to 95% upon water removal. Special precautions to avoid co-distillation of the amine were required, Two different stratagies to avoid the amine loss are presented