Flavonoid Enantiomers and Benzofurans With α-Glucosidase Inhibitory Activity From the Leaves of Morus alba.

Fourteen flavonoids (1-12, 19, and 20) and six 2-arylbenzofurans (13-18), consisting of 10 chiral and 10 achiral compounds, were isolated and identified from the leaves of the famous medicinal plant Morus alba. Nine flavonoids (1-9) of the 10 chiral molecules were further analyzed and separated into the respective enantiomers by chiral HPLC, with the absolute configurations assigned via electronic circular dichroism analysis, which has clarified the puzzles on their optical/enantiomeric purity and configurational assignment in the previous reports. Most isolates showed significant inhibitory activity against the diabetic target α-glucosidase, and the binding mode of compound 13 with the enzyme was further explored, which identified it as a mixed-type inhibitor.