Antiplasmodial quinones from Pentas longiflora and Pentas lanceolata

Abstract

The dichloromethane/methanol (1:1) extracts of the roots of Pentas longiflora and Pentas lanceolata showed low micromolar (IC 50=0. 93μg/mL) in vitro antiplasmodial activity against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum. Chromatographic separation of the extract of Pentas longiflora led to the isolation of the pyranonaphthoquinones pentalongin (1) and psychorubrin (2) with IC 50 values below 1μg/mL and the naphthalene derivative mollugin (3), which showed marginal activity. Similar treatment of Pentas lanceolata led to the isolation of eight anthraquinones (411, IC 50=531μg/mL) of which one is new (5,6-dihydroxydamnacanthol, 11), while three nordamnacanthal (7), lucidin - methyl ether (9), and damnacanthol (10) are reported here for the first time from the genus Pentas. The compounds were identified by NMR and mass spectroscopic techniques. © 2012 Georg Thieme Verlag KG Stuttgart New York.