Schomburgkixanthone, a novel bixanthone from the twigs of <i>Garcinia schomburgkiana</i>

Abstract

A novel bixanthone, named schomburgkixanthone (<b>1</b>), was isolated from the twigs of <i>Garcinia schomburgkiana</i>, along with six known compounds, griffipavixanthone (<b>2</b>), 4-hydroxyxanthone (<b>3</b>), 2-hydroxyxanthone (<b>4</b>), 1,6-dihydroxyxanthone (<b>5</b>), 1,7-dihydroxyxanthone (<b>6</b>), and 1,3,5-trihydroxyxanthone (<b>7</b>). The structure of <b>1</b> was identified by the application of NMR and MS data analyses and comparison with previous reports. Compound <b>1</b> showed the most powerful inhibition of rat intestinal <i>α</i>-glucosidase, with IC₅₀ values of 0.79 for maltase and 1.81 mM for sucrase. Compound <b>2</b> most strongly inhibited sucrase, with an IC₅₀ value of 4.58 mM.