Chemical constituents and antimicrobial activity of the aerial part of <i>Solanum betaceum</i> Cav. (Solanaceae)

A new saponin namely diosgeninoside (25 <i>R</i>-spirost-5-en-3-<i>O</i>-[<i>β</i>-_D-glucopyranosyl (1→2) - <i>β</i>-_D-glucuronic acid]) and a new fatty acid betacic acid: (<i>Z</i>)-8(<i>S</i>*),9(<i>S</i>*),10(<i>R</i>*)-trihydroxy-11-octadecenoic acid together with six known compounds: <i>N</i>-<i>trans</i>-coumaroyl tyramine, ergosta-7,22-dien<i>-</i>3<i>β,</i>5<i>α,6β-</i>triol, <i>β</i>-sitosterol, and <i>β</i>-sitosterol-3-<i>O</i>-<i>β</i>-_D-glucopyranoside, <i>L</i>-threitol and soya-cerebroside I were isolated from the methanolic extract of <i>Solanum betaceum</i>. The structures were elucidated by interpretation of their 1D and 2D NMR spectra and spectrometric data. The methanolic extract, the EtOAc and <i>n</i>-BuOH fractions, and several isolated compounds were tested for antibacterial activity against four bacteria (<i>Staphylococcus aureus</i>; <i>Staphylococcus epidermidis</i>; <i>Escherichia coli</i>; and <i>Pseudomonas aeruginosa</i>). The methanolic extract and the EtOAc fraction showed moderate activity against <i>Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i> with MIC value of 128 µg/mL. Compound <b>1</b> showed moderate activity against <i>Staphylococcus aureus</i> with MIC value of 64 µg/mL.