Steroids with prominent cytotoxic activity against non-small cell lung cancer cells from the Strophanthus divaricatus

Abstract

Four previously undescribed steroids, named sarmutogenin diginoside, sarmutogenin oleandroside, 16-hydroxy-17βH sarmutogenin digitaloside and 12-dehydroxy sarmutogenin diginoside (1–4), along with eight known ones (5–12) were isolated from the stems and leaves of Strophanthus divaricatus. The chemical structures of the new compounds including their absolute configurations, were characterized by extensive spectroscopic methods, electronic circular dichroism (ECD), X-ray diffraction, as well as comparison with literature data. Most of the isolated compounds demonstrated superior antiproliferative activities against A549 non-small cell lung cancer (NSCLC) cells compared to cisplatin, a first-line treatment regimen for NSCLC. Among these, compounds 2 and 12 can potently inhibited the growth of a panel of NSCLC cells by inducing apoptosis and G2/M cell cycle arrest.