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-[β-D-apiosyl-(1 → 6)]-β-D-glucoside, as well as 13 known compounds, was isolated. Their structures were identified based on extensive spectroscopic studies including HR-EI-MS, (1)H, (13)C NMR, DEPT, H-H COSY, HSQC, HMBC and NOESY spectra. The new compound and gigantol were evaluated for their α-glucosidase inhibitory activity, and both displayed more potent α-glucosidase inhibitory activity than acarbose, one of the most potent α-glucosidase inhibitor drugs, with the inhibition rate of 43.4% and 36.7%, respectively, in the concentration of 437.5 μmol/L.