Relative reactivity of substituted acetophenones in enantioselective biocatalytic reduction catalyzed by plant cells of Daucus carota and Petroselinum crispum

We have examined enantioselective bioreduction of acetophenone and its substituted derivatives into corresponding S-alcohols catalyzed by Daucus carota and Petroselinum crispum plant cells in water and isooctane. We found that the nature of the substituent has a profound effect on the relative reactivity of substituted acetophenones and enantioselectivity of biocatalytic reduction. Electron-withdrawing substituents –Br and –NO₂ enhance the initial rate of reaction and yields of products, while electron-donating substituent –OCH₃ decreases them. The reduction rates and yields of products in water were noticeably higher in comparison with similar reductions conducted in isooctane. Correlations between the initial reaction rate and the substituent constant (σ⁺) in the aromatic ring characterizing its nature were established. Comparison of ρ constants of bioreduction catalyzed by D. carota and P. crispum shows that the sensitivity of the reduction to the nature of the substituents is more significant in the case of D. carota biocatalyst. Comparison of ρ constants for D. сarota and P. crispum in water and isooctane indicates that the sensitivity of bioreduction to the nature of the substituent tends to increase from water to isooctane.