Dihydroosajaxanthone: A New Natural Xanthone from the Branches of Garcinia Schomburgkiana Pierre

Garcinia schomburgkiana, locally known in thailand as an edible fruit “ma-dan”, is a plant species of the clusiaceae family which has been reported as sources of a variety of compounds with biological activities. in the phytochemical studies of ma-dan, four xanthones were, for the very first time, isolated from the branch acetone extract of g. schomburgkiana. their structures were determined through the analysis of spectroscopic data (1^h, 13^c-nmr, ir and ms) and the comparison with those previously reported. dihydroosajaxanthone (1), an original synthetic xanthone, is reported herein for the first time as a naturally occurring xanthone, together with three known xanthones: xanthochymone a (2), 1,3,7-trihydroxy-2-(3-hydroxy-3-methylbutyl) xanthone (3) and 1,3,5,6-tetrahydroxyxanthone (4). these compounds, especially dihydroosajaxanthone (1), might be considered as chemotaxonomic markers of the garciniagenus.