Synthesis of lipophilic arbutin ester by enzymatic transesterification in high pressure carbon dioxide.

In this study, a novel one-step enzymatic acylation was developed for the synthesis of hydrophobic arbutin ester, by using supercritical carbon dioxide (SC-CO2) as the reaction solvent. Immobilized Novozym 435 from Candida antarctica was identified as the best biocatalyst for producing arbutin palmitate through transesterification between arbutin and palmitic acid ethyl ester in SC-CO2. A transesterification yield of 85.21 % was obtained in batch operation using palmitic acid ethyl ester as the acyl donor, hexane/propylene glycol as the co-solvent and Novozym 435 as the enzyme at 10 MPa and 60 °C for 20 h in SC-CO2. The yield of arbutin palmitate increased with increasing temperature over the range of 40-60 °C in the current study. Operating at an arbutin/palmitic acid ethyl ester molar ratio of 5.0, the conversion of arbutin decreased, probably due to an inhibitory effect of the high concentration of palmitic acid ethyl ester on the enzyme. The 38 % original enzyme activity of Novozym 435 was maintained after being used for 3 cycles (60 h) under optimized conditions.

Enzymatic synthesis of isomaltotriose palmitate and evaluation of its emulsifying property.

Enzymatic syntheses of oligosaccharide fatty acid esters are important owing to their wide range of industrial applications in the food, cosmetic, and pharmaceutical industries. Transesterification of isomaltotriose and palmitic acid vinyl ester, catalyzed by the metalloprotease thermolysin, was performed in organic solvents. The process parameters (reaction time and temperature) were optimized to achieve the highest yield of isomaltotriose palmitate (IP). The water content of the reaction system played a key role in the acylation of isomaltotriose. Dimethyl sulfoxide was thought to be the most suitable reaction medium by taking the degree of substitution of the modified isomaltotriose into account. The optimum reaction time, temperature, water content, and enzyme concentration were 24h, 45°C, 40%, and 0.05%, respectively, under which the product yield was as high as 89.7%. The enzyme operational stability study showed that thermolysin retained 51.5% of its initial activity for the synthesis of IP (even after repeated use for 72h). Moreover, test results showed that the emulsifying capacity and emulsion stability of IP are 107.5mL oil/g ester and 16.3%, respectively.

Lipase-catalyzed synthesis of palmitanilide: Kinetic model and antimicrobial activity study.

Enzymatic syntheses of fatty acid anilides are important owing to their wide range of industrial applications in detergents, shampoo, cosmetics, and surfactant formulations. The amidation reaction of Mucor miehei lipase Lipozyme IM20 was investigated for direct amidation of triacylglycerol in organic solvents. The process parameters (reaction temperature, substrate molar ratio, enzyme amount) were optimized to achieve the highest yield of anilide. The maximum yield of palmitanilide (88.9%) was achieved after 24 h of reaction at 40 °C at an enzyme concentration of 1.4% (70 mg). Kinetics of lipase-catalyzed amidation of aniline with tripalmitin has been investigated. The reaction rate could be described in terms of the Michaelis-Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. The kinetic constants were estimated by using non-linear regression method using enzyme kinetic modules. The enzyme operational stability study showed that Lipozyme IM20 retained 38.1% of the initial activity for the synthesis of palmitanilide (even after repeated use for 48 h). Palmitanilide, a fatty acid amide, exhibited potent antimicrobial activity toward Bacillus cereus.

Enzymatic synthesis of sialic acid derivative by immobilized lipase from Candida antarctica.

The effects of important reaction parameters on the enhancement of sialic acid derivative lipophilic properties through the lipase-catalyzed esterification of N-acetyl neuraminic acid methyl ester are investigated in this study. It is found that the lipase Novozym 435 from Candida antarctica is particularly useful in the preparation of sialic acid methyl ester monononanoate (SAMEMN). The optimum temperature for the SAMEMN synthesis reaction using Novozym 435 is 60°C, and nonanoic anhydride is found to be the best substrate among all acyl donors. The Novozym 435-catalyzed esterification of N-acetyl neuraminic acid methyl ester gave a maximum yield of 87.7% after 6h in acetonitrile at 60°C. Because the novel method developed is simple, yet effective, it could potentially be used industrially for the production of sialic acid derivatives.

Lipase-catalyzed production of a bioactive terpene ester in supercritical carbon dioxide.

Direct esterification of alpha-terpineol and acetic anhydride catalyzed by Candida rugosa lipase was performed in supercritical carbon dioxide (SC-CO(2)) with organic solvent serving as co-solvents. The highest yield of terpinyl acetate after 1.5h of reaction performance (95.1%) was obtained in SC-CO(2) with n-heptane serving as a co-solvent and immobilized Candida rugosa lipase as an enzyme at 50 degrees C. The optimal pressure for terpinyl acetate synthesis in SC-CO(2) medium was 10 MPa. Acetic anhydride was the best substrate among all acyl donors. Anhydrous enzyme was found to be the best for the esterification reaction. Lipase immobilization increased the catalytic efficiency up to 1.8-fold. The analysis of the initial rate data showed that reaction followed a Ping-Pong Bi-Bi mechanism with inhibition by acetic anhydride. The kinetic constants were obtained by multiple regression analysis of experimental findings. The reaction went smoothly without the use of hazardous reactants, and the developed method is useful for industrial application.

Synthesis of terpinyl acetate by lipase-catalyzed esterification in supercritical carbon dioxide.

Terpinyl acetate was successfully synthesized from alpha-terpineol and acetic anhydride in supercritical carbon dioxide (SC-CO(2)) by enzymatic catalysis. Five different lipases (Candida rugosa type VII, Amano PS, Amano AP-6, Amano G and Lipozyme RM IM) as biocatalysts for the terpinyl acetate synthesis were compared. An esterification extent of 53.0% was obtained in continuous operation using acetic anhydride as acyl donor and C. rugosa lipase as enzyme at 10MPa and 50 degrees C for 1.5h. Temperature in the range of 35-50 degrees C demonstrated that the yield of terpinyl acetate increase with temperature increase in the current study. Operating at a alpha-terpineol/acetic anhydride molar ratio 3.0, the conversion of alcohol decreased, probably due to an inhibitory effect on enzyme by high concentration of acetic anhydride or by formation of acetic acid. However, the enzyme activity still remained more than 50% after 10.5h repeated esterification in a batch under optimized conditions.