Cytotoxic withaphysalins from Physalis minima

A novel withanolide, withaphysalin P (1) with a nine-membered ring, and six other new withaphysalins, 2-7, together with the three known withaphysalins 8-10 were isolated from Physalis minima L. The structures were deduced by means of spectroscopic analyses, and that of withaphysalin P (1) was confirmed by a single-crystal X-ray diffraction analysis. Plausible biosynthetic pathways were postulated (Scheme 1). All compounds were tested for their antiproliferative activities toward the human colorectal-carcinoma HCT-116 cells and human nonsmall-cell lung-cancer NCI-H460 cells (Table 4). Compounds 1-3, 7-10, 7a, and 7b displayed moderate cytotoxic activity against the two human cancer cell lines.