Four Prenylflavone Derivatives with Antiplasmodial Activities from the Stem of Tephrosia purpurea subsp. leptostachya

Four new flavones with modified prenyl groups, namely (E)-5-hydroxytephrostachin (1), purleptone (2), (E)-5-hydroxyanhydrotephrostachin (3), and terpurlepflavone (4), along with seven known compounds (5–11), were isolated from the CH(2)Cl(2)/MeOH (1:1) extract of the stem of Tephrosia purpurea subsp. leptostachya, a widely used medicinal plant. Their structures were elucidated on the basis of NMR spectroscopic and mass spectrometric evidence. Some of the isolated compounds showed antiplasmodial activity against the chloroquine-sensitive D6 strains of Plasmodium falciparum, with (E)-5-hydroxytephrostachin (1) being the most active, IC(50) 1.7 ± 0.1 μM, with relatively low cytotoxicity, IC(50) > 21 μM, against four cell-lines.