Abstract
Coccinia grandis or ivy gourd is an edible plant. Its leaves and fruits are used as vegetable in many countries. Many works on antidiabetic activity of a crude extract of C. grandis, i.e., in vitro, in vivo, and clinical trials studies, have been reported. Profiles of the antidiabetic compounds were previously proposed by using LC-MS or GC-MS. However, the compounds responsible for antidiabetic activity have rarely been isolated and characterized by analysis of 1D and 2D NMR data. In the present work, UHPLC-ESI-QTOF-MS/MS analysis and GNPS molecular networking were used to guide the isolation of alpha-glucosidase inhibitors from an extract of C. grandis leaves. Seven flavonoid glycosides including rutin (1), kaempferol 3-O-rutinoside (2) or nicotiflorin, kaempferol 3-O-robinobioside (3), quercetin 3-O-robinobioside (4), quercetin 3-O-beta-D-apiofuranosyl-(1 -> 2)-[alpha-L-rhamnopyranosyl-(1 -> 6)]-beta-D-glucopyranoside (5) or CTN-986, kaempferol 3-O-beta-D-api-furanosyl-(1 -> 2)-[alpha-L-rhamnopyranosyl-(1 -> 6)]-beta-D-glucopyranoside (6), and kaempferol 3-O-beta-D-apiofuranosyl-(1 -> 2)-[alpha-L-rhamnopyranosyl-(1 -> 6)]-beta-D-galactopyranoside (7) were isolated from C. grandis leaves. This is the first report of glycosides containing apiose sugar in the genus Coccinia. These glycosides exhibited remarkable alpha-glucosidase inhibitory activity, being 4.4-10.3 times more potent than acarbose. Moreover, they also displayed virucidal activity against influenza A virus H1N1, as revealed by the ASTM E1053-20 method.
