Production of precursors for anti-Alzheimer drugs: Asymmetric bioreduction in a packed-bed bioreactor using immobilized D. carota cells

Plant-Mediated Enantioselective Transformation of Indan-1-one and Indan-1-ol. Part 2

The main purpose of this publication was to obtain the S-enantiomer of indan-1-ol with high enantiomeric excess and satisfactory yield. In our research, we used carrot callus cultures (Daucus carota L.), whereby the enzymatic system reduced indan-1-one and oxidized indan-1-ol. During the reaction of reduction, after five days, we received over 50% conversion, with the enantiomeric excess of the formed S-alcohol above 99%. In turn, during the oxidation of racemic indan-1-ol after 15 days, 36.7% of alcohol with an enantiomeric excess 57.4% S(+) remained in the reaction mixture. In addition, our research confirmed that the reactions of reduction and oxidation are competing reactions during the transformation of indan-1-ol and indan-1-one in carrot callus cultures.

Plant-Mediated Enantioselective Transformation of Indan-1-One and Indan-1-ol

The main purpose of this work was to discover the way to obtain pure enantiomers of indan-1-ol. The subject of the study was the ability of the plant enzyme system to reduce the carbonyl group of indan-1-one, as well as to oxidize the hydroxyl group of racemic indan-1-ol. Locally available fruit and vegetables were selected for stereoselective biotransformation. During the reduction, mainly alcohol of the S-(+)-configuration with a high enantiomeric excess (ee = 99%) was obtained. The opposite enantiomer was obtained in bioreduction with the apple and parsley. Racemic indan-1-ol was oxidized by all catalysts. The best result was obtained for the Jerusalem artichoke: Over 50% conversion was observed after 1 h, and the enantiomeric excess of unreacted R-(–)-indan1-ol was 100%.

Green synthesis of enantiopure quinoxaline alcohols using Daucus carota

Green chemistry comprises a new approach in the synthesis of biologically active compounds using biocatalysts, thus diminishing the hazards for human health and environmental pollution. Asymmetric bioreduction is one of the most widely employed strategies in chemoenzymatic synthesis to produce enantiomerically pure chiral alcohols. The present study highlights the use biocatalyst Daucus carota for selective bioreduction of quinoxaline ketones 1a-6a to their corresponding optically pure alcohols 1b-6b in high yields (up to 84%) and good enantioselectivity (up to 98%). The absolute configuration of the chiral product (R)-1-(3-methyl 7-nitroquinoxalin-2-yl) ethan-1-ol 2b was confirmed by X-ray crystallography studies. The chiral R-configuration of the products obtained was confirmed by absolute configuration studies and was assigned following anti-Prelogs rule. Quinoxaline pharmacophores form a part of well-known potent drug molecules; hence, the chiral products were studied for determination of their molecular properties using SwissADME property analyser. All the chiral products show no Lipinski rule violations and are expected to have good oral bioavailability. As per the molecular properties prediction studies, the compound 6b (R)-1-(6,7-dichloro-3- methylquinoxalin-2-yl) ethanol is observed to show the best physicochemical properties to be a good lead molecule. Thus, the sustainable methodology was developed, and it confirms the synthesis of novel quinoxaline chiral alcohols in a simple, inexpensive, and eco-friendly condition using D carota.