alpha-glucosidase inhibitors from Commelina communis

A methanolic extract of Commelina communis showed potent inhibitory activit y against alpha-glucosidase. One pyrrolidine alkaloid, 2,5-dihydroxymethyl- 3,4-dihydroxypyrrolidine (DMDP, 1) and four piperidine alkaloids, 1-deoxyma nnojirimycin (2), 1-deoxynojirimycin (3), alpha-homonojirimycin (4) and 7-O -beta-D-glucopyranosyl alpha-homonojirimycin (5) were isolated by bioassay- directed fractionation and separation. These compounds have been identified for the first time from Commelina communis, supporting the pharmacological basis of this plant that has been used as a traditional herbal medicine fo r the treatment of diabetes.