Anti-infective assessment of <i>Senecio smithioides</i> (Asteraceae) and isolation of 9-oxoeuryopsin, a furanoeremophilane-type sesquiterpene with antiplasmodial activity

<p>The search for anti-infective activity in the antipyretic plant <i>Senecio smithioides</i> was conducted. Petroleum ether (PE), dichloromethane (CH₂Cl₂), ethyl acetate (EtOAc) and hydroethanolic (96% EtOH) extracts, and compounds 9-oxoeuryopsin (<b>1</b>), epoxydecompostin (<b>2</b>) and senecionine (<b>3</b>) were obtained from the aerial parts. All extracts and <b>1</b> were tested against chloroquine-resistant strain of <i>Plasmodium falciparum</i> (ref. chloroquine), <i>Trypanosoma cruzi</i> (ref. nifurtimox), <i>Leishmania braziliensis</i>, <i>Leishmania amazonensis</i> and <i>Leishmania donovani</i> (ref. pentamidine), <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> (ref. gentamicin) and, <i>Neurospora crassa</i> and <i>Candida albicans</i> (ref. ketoconazole). The PE extract exhibited the strongest <i>in vitro</i> activity against <i>Plasmodium falciparum</i> IC₅₀ < 1.0 μg/mL. <b>1</b> was established as a potent antiplasmodial compound with an IC₅₀ = 1.2 μg/mL, 5.2 μM. Other antiparasitic activities were recorded for all extracts and <b>1</b>. Antibacterial and antifungal activity was negligible.