Two new steroidal alkaloids from the mature fruits of Solanum nigrum

Two previously undescribed steroidal alkaloids, compounds 1–2, were isolated from the ripe fruits of Solanum nigrum , along with seven known metabolites (3–9). Based on spectroscopic and chemical evidence, including IR, NMR, and HR-ESI-MS analyses, the structures of the isolated compounds were elucidated as 12 β -hydroxy-(3 β ,22 α ,25 R )-spirosol-5-en-27-acid-3- O - α - L -rhamnopyranosyl-(1→2)- β - D -glucopyranosyl-(1→3)]- β - D -galacopyranoside and 12 β -hydroxy-(3 β ,22 α ,25 R )-spirosol-5-en-27-acid-3- O - α - L -rhamnopyranosyl-(1→2)-[ α - L -rhamnopyranosyl-(1→4)]- β - D -glucopyranoside. Four steroidal alkaloids (compounds 1–2 and 4–5) were tested for their anti-proliferative effects against the HT-29, A549, and Lewis cell lines. Both of the previously isolated compounds inhibited the proliferation of these three cell lines in a dose-dependent manner, with the most significant effect being in the A549 cells, but neither reached IC 50 at 50 μM. These results revealed that S . nigrum had weak cytotoxicity, indicating its clinical safety as a traditional anti-tumor herbal medicine. • Two undescribed steroidal alkaloids were isolated from Solanum nigrum. • The structure of compounds were determined by analysis of OR, IR, HR-ESI-MS, and NMR spectra. • Cytotoxicity evaluation against HT-29, A549 and Lewis was examined.