Asymmetric reduction of ketones by biocatalysis using medlar (Mespilus germanicaL) fruit grown in Algeria

The biocatalytic reduction of ketones was performed using medlar fruit (Mespilus germanica L), which is grown in large amounts in Algeria. Experiments were performed using aqueous medium with fresh medlar. Prochiral heteroaryl ketones containing furan, thiophene, chroman, and thiochroman moieties were reduced with enantiomeric excess (ee) of up to 98%. High enantioselectivities have been observed especially for the bioreduction of tetralone 4 and thiochromanone 5 with ee of 89% and 98%, respectively. Bioreduction using different parts of medlar indicate that chromanone 6 was reduced with good asymmetric inductions 77% < ee < 85% whichever part of fruit was employed (whole, flesh, or juice) and medlar juice exhibited the best activity.