Antiplasmodial β-triketones from the flowers of the Australian tree Angophora woodsiana

Abstract

Chemical investigations of the MeOH extract of air dried flowers of the Australian tree Angophora woodsiana (Myrtaceae) yielded two new β-triketones, woodsianones A and B (1, 2) and nine known β-triketones (3-11). Woodsianone A is a β-triketone-sesquiterpene adduct and woodsianone B is a β-triketone epoxide derivative. The structures of the new and known compounds were elucidated from the analysis of 1D/2D NMR and MS data. The relative configurations of the compounds were determined from analysis of ¹H-¹H coupling constants and ROESY correlations. All compounds (1-11) had antiplasmodial activity against the chloroquine sensitive strain 3D7. The known compound rhodomyrtone (5) and new compound woodsianone B (2) showed moderate antiplasmodial activities against the 3D7 strain (1.84µM and 3.00µM, respectively) and chloroquine resistant strain Dd2 (4.00µM and 2.53µM, respectively).

Keywords: Angophora woodsiana; Antiplasmodial activity; Myrtaceae; β-Triketones.