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 Garcinia genus.