Antiproliferative Withanolides from Datura wrightii

A new withanolide, named withawrightolide (1), and four known withanolides (2–5) were isolated from the aerial parts of Datura wrightii. The structure of compound 1was elucidated through 2D NMR and other spectroscopic techniques. In addition, the structure of withametelin L (2) was confirmed by X-ray crystallographic analysis. Using MTS viability assays, withanolides 1–5showed antiproliferative activities against human glioblastoma (U251 and U87), head and neck squamous cell carcinoma (MDA-1986), and normal fetal lung fibroblast (MRC-5) cells with IC50values in the range between 0.56 and 5.6 μM.