Antidiabetic activity of methanolic extract, petroleum ether, ethyl acetate and n-butanol fractions of Ipomoea cairica (L.) Sweet leaves was performed in-vitro using α-glucosidase and α-amylase inhibition methods. Phytochemical study of the ethyl acetate fraction which possessed the highest antidiabetic activity led to isolation of five flavonoids for the first time from this plant, including two rare flavonoid sulphates, ombuin-3-sulphate [1] and rhamnetin-3-sulphate [2] and three flavonoid glycosides, kaempferol 7-O-α-L-rhamnopyranoside [3], kaempferol 3,7-di-O-α-L-rhamnopyranoside [4] and quercetin 3-O-α-L-arabinopyranoside [5]. The 1H and 13C NMR of 1 and 13C NMR of 2, were reported here for the first time. Compounds [1-4] showed a concentration-dependent in-vitro inhibitory activity against α-glucosidase and α-amylase. Furthermore, in-silico study predicted that compounds (1-5) showed good interactions with α-glucosidase, α-amylase, and protein tyrosine phosphatase 1b.
Keywords: Convolvulaceae; Ipomoea cairica (L.) Sweet; diabetes; molecular docking; sulphated flavonoids; tyrosine phosphatase 1b.