Anthelmintic metabolites of Dalea ornata (Fabaceae)

Ancylostema ceylanicum, or hookworm, is a blood feeding intestinal parasite and a major health burden, with approximately a billion people infected in tropical and subtropical regions of the world. Hookworm infection often leads to iron-deficiency anemia, weight loss, stunted growth and malnutrition. Control strategies have relied on mass treatment with benzimidazoles, however, there has been an increase in resistance of hookworms to these drugs. Consequently, there is an urgent need to develop alternative therapies. The methanolic crude extract of aerial portions of Dalea ornata (Fabaceae) exhibited anthelminthic activity toward A. ceylanicum in an ex vivo assay. Extracts of D. ornata roots were essentially inactive. Increased potency, compared to extracts, was observed in a chromatographically enriched fraction, with worm mortality rates of 80 – 100% after 72h for all doses (100, 50, 10µg/mL). Dose-dependence was also observed in the assay. Further purification by Sephadex LH-20 chromatography and successive gradient separations over silica gel has led to twelve phenolic compounds. Structure determinations were accomplished primarily by extensive 1D and 2D NMR spectroscopy and mass spectrometry. Details and results of the ex vivo assay and structures of the isolated compounds will be presented.

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