Isolation of α-glucosidase inhibitors including a new flavonol glycoside from Dendrobium devonianum

From the whole plant of Dendrobium devonianum, a new flavonol glycoside, 5-hydroxy-3-methoxy-flavone-7-O-[beta-D-apiosyl-(1 -> 6)]-beta-D-glucoside, as well as 13 known compounds, was isolated. Their structures were identified based on extensive spectroscopic studies including HR-EI-MS, H-1, C-13 NMR, DEPT, H-H COSY, HSQC, HMBC and NOESY spectra. The new compound and gigantol were evaluated for their alpha-glucosidase inhibitory activity, and both displayed more potent alpha-glucosidase inhibitory activity than acarbose, one of the most potent alpha-glucosidase inhibitor drugs, with the inhibition rate of 43.4% and 36.7%, respectively, in the concentration of 437.5 mu mol/L.