A new withanolide from <i>saponaria officinalis</i> and its antimicrobial and cytotoxic activities

A new compound, 5β,6β-epoxy-20α,24β,25α-trihydroxy-1,3-dioxowitha-2-enolide (<b>1</b>), and two known compounds, gracillin (<b>2</b>) and 5α-hydroxylaxogenin (<b>3</b>), have been isolated from the aerial part of <i>Saponaria officinalis</i>. High-resolution mass spectrometry and 1D and 2D NMR spectroscopy analysis data were used to establish the structure of the new compound. The antimicrobial activity of the new compound against some opportunistic strains of microorganisms and its cytotoxicity against two cancer cell lines and two healthy cell lines <i>in vitro</i> were studied. 5β,6β-Epoxy-20α,24β,25α-trihydroxy-1,3-dioxowitha-2-enolide was found to be most active against three bacterial strains: <i>Staphylococcus aureus</i>, <i>Bacillus subtilis</i>, and <i>Pseudomonas aeruginosa</i>, with inhibition zone diameters of 21.04 ± 0.10 mm, 22.08 ± 0.12 mm, and 18.12 ± 0.13 mm, respectively. Compound <b>1</b> also showed significant cytotoxicity against HEp-2 and HeLa cell lines (IC₅₀ = 23.2 μM and 54.9 μM, respectively).