Trichilones A–E: New Limonoids from Trichilia adolfi

Abstract

In addition to the trichilianones A-D recently reported from <i>Trichilia adolfi</i>, a continuing investigation of the chemical constituents of the ethanol extract of the bark of this medicinal plant yielded the five new limonoids <b>1</b>-<b>5</b>. They are characterized by having four fused rings and are new examples of prieurianin-type limonoids, having a ε-lactone which in <b>4</b> and <b>5</b> is α, β- unsaturated. The structures of the isolated metabolites were determined by high field NMR spectroscopy and HR mass spectrometry. The new metabolites were shown to have the ε-lactone fused with a tetrahydrofuran ring which is connected to an oxidized hexane ring joined with a cyclo-pentanone having a 3-furanyl substituent. As the crude extract possesses antileishmanial activity, the compounds were assayed for cytotoxic and antiparasitic activities in vitro in murine macrophage cells (raw 264.7 cells) and in <i>Leishmania amazoniensis</i> as well as <i>L. braziliensis</i> promastigotes. Metabolites <b>1</b>-<b>3</b> and <b>5</b> showed moderate cytotoxicity (between 30-94 µg/mL) but are not responsible for the antileishmanial effect of the extract.