A new benzophenone, and the antiplasmodial activities of the constituents of <i>Securidaca longipedunculata</i> fresen (Polygalaceae)

Abstract

Extracts from <i>Securidaca longipedunculata</i> showed antiplasmodial activities against reference clones and clinical isolates using SYBR Green I method. A new benzophenone, 2,3,4,5-tetramethoxybenzophenone (<b>1</b>) was isolated and characterized along with seven known compounds: 4-hydroxy-2,3-dimethoxybenzophenone (<b>2</b>); 3-hydroxy-5-methoxybiphenyl (<b>3</b>), methyl-2-hydroxy-6-methoxybenzoate (<b>4</b>), benzyl-2-hydroxy-6-methoxybenzoate (<b>5</b>), 2-hydroxy-6-methoxybenzoic acid (<b>6</b>), 2,4,5-trimethoxybenzophenone (<b>7</b>) and 2-methoxy-3,4-methylenedioxybenzophenone (<b>8</b>). Compounds <b>1</b> and <b>2</b> showed <i>ex vivo</i> antiplasmodial activities (IC₅₀ 28.8 μM and 18.6 μM, respectively); while <b>5</b> and <b>8</b> showed <i>in vivo</i> activities (IC₅₀ 19.7 μM and 14.5 μM, respectively) against D6 strain. In a cytotoxicity assay, all the extracts (with an exception of the MeOH extract of the leaves) and pure compounds were not toxic to the normal LO2 and BEAS cell-lines, while the methanol roots extract (IC₅₀ 66.4 µg/mL against A549, and 77.4 µg/mL against HepG2), compounds <b>6</b> (IC₅₀ 22.2 µM against A549) and <b>7</b> (IC₅₀ 45.2 µM against HepG2) were weakly active against cancerous cell-lines.