Biorredução de cetonas aromáticas pró-quirais empregando Pseudomonas sp. isolada de Nopalea cochenellifera (L.) Salm Dyck

Abstract

Herein we describe the study biocatalytic potential of the whole cell of microorganisms isolated from a plant belonging to Cactacea family, Nopalea cochenillifera (L.) Salm- Dyck, popularly known as “palma doce” or “palma forrageira”. The microorganisms were isolated by induction technique using as acetophenone susbtrate. Among the microorganisms strains (I-1, I-2, I-3, I-4) only I-2, (Pseudomonas sp), was effective as biocatalyst in reducing the acetophenone. The best conditions for carrying out the bioreduction of acetophenone were as follows: 1g of resting cells of Pseudomonas sp, resuspended in buffer solution pH 7, at 28 ° C and rotation of 175 r.p.m for 4 days, obtaining the (S)-1-phenylethanol with conversion of 77% e.e. and 89%. The bioreduction study, using the Pseudomonas sp strain, was extended to the following derivatives of acetophenone, 4-methoxy-acetophenone (2a), 4-methyl acetophenone (3a), 4-nitro-acetophenone (4a), 4 -bromo-acetophenone (5a), 4-chloro-acetophenone (6a), 4-fluoro-acetophenone (7a), 3-methoxy-acetophenone (8a), 3-methyl acetophenone (9a), 3-nitro-acetophenone (10a) 2-methoxy-acetophenone (11a), 2-methyl acetophenone (12a), 2-nitro-acetophenone (13a), 2-bromo-acetophenone (14a), 2-chloro-acetophenone (15a), 2 - fluoro-acetophenone (16a). It is not worthy that all the alcohols were obtained with Prelog selectivity (S configuration). In general, the best results were obtained for the derivatives of acetophenone with substituent methoxyl, methyl, nitro and bromine in position - ortho (e.e. of 94 to > 99% conversion and 23-80%). With respect to the chlorine and fluorine substituents, the best results of selectivity and enzymatic activity were obtained for the – para substituted derivatives (e.e. 93% and 73% conversion, 83% e.e. and conversion of 51%, respectively).