Role of the side chain stereochemistry in the α-glucosidase inhibitory activity of kotalanol, a potent natural α-glucosidase inhibitor

Synthesis and evaluation of four diastereomers (9a, 9b, 9c and 9d) of kotalanol, a potent alpha-glucosidase inhibitor isolated from an Ayurvedic medicinal plant Salacia species, are described. Stereo-inversion at C-3' and C-4' of kotalanol (2) caused significant decrease of the inhibitory activities against maltase and sucrase, whereas inhibitory activity against isomaltase sustained, thus resulted in exerting selectivity against isomaltase. (C) 2011 Elsevier Ltd. All rights reserved.