Perisomalien A, a new cytotoxic scalarane sesterterpene from the fruits of Periploca somaliensis.

The CHCl₃ fraction of MeOH extract of Periploca somaliensis (family Asclepiadaceae) fruits afforded a new scalarane sesterterpene, namely perisomalien A (1), along with lupeol acetate (2), β-amyrin (3), cycloart-23Z-ene-3β,25-diol (4), and β-sitosterol-3-O-β-D-glucopyranoside (5). Their chemical structures were established by various spectroscopic analyses, in addition to comparison with the formerly reported data. Moreover, the cytotoxic activity of these metabolites was assessed towards MCF-7, HepG2, and HCT-116 tumour cell lines using sulforhodamine B (SRB) assay. Compound 4 showed the most potent cytotoxic profile with IC₅₀ 9.0 µM towards MCF-7, compared to doxorubicin (IC₅₀ 0.18 µM). Also, 1 and 4 possessed the most potent effect towards HepG2 with IC₅₀s 26.7 and 25.9 μM, respectively. In addition, all tested compounds showed cytotoxic effects with IC₅₀ values ranging from 19.9 to 39.3 µM against HCT-116.