Chemical constituents from the bark of the Cameroonian mahogany Trichilia emetica Vahl (Meliaceae)

Phytochemical investigation of the stem bark extract of Trichilia emetica led to the isolation of two new naturally occurring compounds including a prieurianin-class limonoid named trichirokin (1) and the steroid ergosta-5,24(28)-diene-3S, 16S, 20S-triol (4), along with nine known compounds characterized as rohituka-3 (3), rohituka-9 (2), scopoletin, benzoic acid, protocatechuic acid, lignoceric acid, beta-sitosterol, stigmasterol and beta-sitosterol-3-O-beta-D-glucopyranoside. The crystal structures of rohituka-3 (3) and ergosta-5,24(28)-diene-3S, 16S, 20S-triol (4) are reported here for the first time. The structures of the compounds were elucidated by extensive spectroscopic and spectrometric data interpretation. The stereochemistry of compound 1 was established on the basis of its NOESY spectrum and the comparison of its optical rotation value with that of its congener 2. None of the reported compounds displayed antibacterial or cytotoxic activity.