Polycyclic Phenol Derivatives from the Leaves of and Their Antibacterial and α-Glucosidase Inhibitory Activity.

Three new polycyclic phenol derivatives, 2-acetyl-4-hydroxy-6H-furo [2,3-g]chromen-6-one (), 2-(1',2'-dihydroxypropan-2'-yl)-4-hydroxy-6H-furo [2,3-g][1]benzopyran-6-one () and 3,8,10-trihydroxy-4,9-dimethoxy-6H-benzo[c]chromen-6-one (), along with seven known ones (-, and ) were isolated for the first time from the leaves of . Their structures were determined by spectroscopic analysis and comparison with literature-reported data. These compounds were tested for their in vitro antibacterial activity against four Gram-(+) bacteria: (), methicillin-resistant (), (), (), and the Gram-(-) bacterium . Compounds , , and showed antibacterial activity toward , and with MIC values ranging from 7.8 to 62.5 µg/mL, but they were inactive to . Compound not only showed the best antibacterial activity against , and , but it further displayed significant antibacterial activity against (MIC 1.95 µg/mL) even stronger than vancomycin (MIC 3.9 µg/mL). No compounds showed inhibitory activity toward . Further bioassay indicated that compounds , , , , and showed in vitro -glucosidase inhibitory activity, among which compound displayed the best -glucosidase inhibitory activity with IC value (0.026 mM) about 15-fold stronger than the reference compound acarbose (IC 0.408 mM). These results suggested that compounds , and were potentially highly valuable compounds worthy of consideration to be further developed as an effective anti- agent or effective -glucosidase inhibitors, respectively. In addition, the obtained data also supported that was rich in structurally diverse bioactive compounds worthy of further investigation, at least in searching for potential antibiotics and -glucosidase inhibitors.