Withanolides from the stems and leaves of Physalis pubescens and their cytotoxic activity.

A phytochemical study of Physalis pubescens L. afforded twelve compounds, including six new withanolides (1, 4, and 6i-9), four new withanolide glucosides (2, 3, 5, and 6), and two known withanolides (10 and 11). Their structures were established via extensive spectroscopic analysis. The absolute configuration of 3 was assigned using X-ray crystallography, and the absolute configurations of the 1,2-diol moiety in 1 were determined using the in situ dimolybdenum electronic circular dichroism method. Compounds 7, 9, and 10 exhibited significant cytotoxicity against human prostate cancer cells (C4-2B and 22Rvl), human renal carcinoma cells (786-O, A-498, Caki-2, and ACHN), human melanoma cells (A375 and A375-S2), and human normal hepatic cell line (L02) with IC50 values in the range of 0.17-5.30μM.