Isolation of steroidal saponins newly reported from <i>Solanum nigrum</i> and evaluation of cytotoxicity against HeLa cells

Cervical cancer remains a major cause of mortality worldwide, highlighting the need for novel therapeutic candidates with improved specificity and reduced adverse effects. Solanum nigrum is a medicinal plant with diverse bioactivities, and its anticancer potential has been frequently associated with steroidal saponins. In this study, bioactivity-guided fractionation of S. nigrum leaves afforded three furostane-type steroidal saponins (compounds 1–3), whose structures were elucidated by UPLC–QTOF–MS and extensive 1D/2D NMR analyses. Compound 2 was identified as the known saponin uttroside B, whereas compounds 1 and 3 were isolated from S. nigrum for the first time, including the C-25 epimer of uttroside B and tribuluside A. All compounds were evaluated for in vitro cytotoxicity against the human cervical cancer cell line HeLa and showed dose-dependent antiproliferative activity, with tribuluside A displaying the highest potency. Further biological evaluation of tribuluside A indicated suppression of colony formation and migration, accompanied by G2/M-phase accumulation and apoptosis induction. Overall, these findings provide compound-level evidence supporting S. nigrum steroidal saponins as bioactive constituents relevant to cervical cancer models.