Acylated Flavonoid from Vaccinium Corymbosum (Ericaceae) Flowers with Yeast α-Glucosidase Inhibitory Activity

Purpose: To isolate and identify chemical constituents with yeast α-glucosidase inhibitory activity from the methanol extract of V. myrtillus (blueberry) flowers. Methods: The active fraction (ethyl acetate extract) were chromatographed on C18 MPLC column, Sephadex LH-20 column and semi-preparative HPLC column. The isolated compounds were identified by the extensive ^1H-nuclear magnetic resonance spectroscopy (NMR), ^13C-NMR, 2D-NMR and high resolution mass spectral (HR-MS) analyses. Results: Two phenolic compounds, an acylated flavonoid and a coumaric acid derivative, were isolated and identified as isorhamnetin-3-O-(6 -O-coumaroyl)-β-D-glucoside (1) and cis-cinnamic acid methyl (2). Compound 1 showed powerful α-glucosidase inhibitory activity and in this regard, was superior to the positive drug, acarbose. Conclusion: Compounds 1 and 2 were isolated for the first time from this species and the genus of Vaccinium. This is the first report on characterization of these phenolic compounds and the possible utilization of blueberry flowers for nutraceutical and functional food applications.