Withanolides from var. and the Relative Configurational Revision of Some Known Analogs.

var. is a plant possessing abundant withanolides, but in-depth research is lacking. In our ongoing study of var. , 15 previously undescribed withanolides (-), along with 21 known analogs (-), were isolated from the whole plant. The structures of the withanolides (-) were elucidated based on analysis of their 1D and 2D NMR, HRESIMS, and ECD data. Additionally, the application of γ-gauche effects with the help of ROESY correlations led to the formulation of empirical rules for withanolides with 14-OH/15-OAc to rapidly determine the 14-OH orientations, making it possible to propose configurational revisions of 19 previously reported analogs (-). Withanolides , -, and showed potent cytotoxic activities against three human cancer cell lines (HCT-116, MDA-MB-231, and A549).