BIOCATALYTIC REDUCTION OF 1-(4-METHYLPHENYL)ETHANONE

Abstract

R- and S-1-(4-Methylphenyl)ethanols serve as a component of the essential oil from some plants in the ginger family and are used as flavoring agents in the production of perfumes, soap fragrances, and synthetic detergents. These compounds exhibit antibacterial activity against Pseudomonas aeruginosa. In this article we studied biotransformation of 1-(4-methylphenyl)ethanone catalyzed by P. crispum cells. It was found that enantioselective reduction of 1-(4-methylphenyl)ethanone catalyzed by P. crispum cells in an aqueous medium at 23-27 °C for 48 h results in formation of (S)-(–)-1-(4-methyl)ethanol with 49% yield (96% ee). Further transformation of initial ketone for 144 h as in the case of similar reduction catalyzed by D. carota cells leads to a slight increase in the yield of alcohol to 51%. However, the optical purity decreases to 80% ee. The bioreduction of 1-(4-methylphenyl)ethanone catalyzed by P.crispum cells was also studied in the presence of exogenous reducing agents (ethanol, isopropanol, or glucose), which are known to significantly affect the yield of the product and the enantioselectivity of the process. Transformation of 1-(4-methylphenyl)ethanone in the presence of ethanol (1-5%) or isopropanol (1-5%) for 144 h leads to (S)-(–)-1-(4-methylphenyl)ethanol with poor yields and optical purity. The reduction of 1-(4-methylphenyl)ethanone in the presence of isopropanol (1-3%) for 72 h leads to a decrease in the yield of (S)-(–)-1-(4-methylphenyl)ethanol, while the concentration of the initial ketone increases. Biotransformation of 1-(4-methylphenyl)ethanone for 144 h in the presence of an equimolar amount of glucose leads to an increase in the yield of (S)-(–)-1-(4-methylphenyl)ethanol to 52% (96% ee).