27-O-(tert-Butyldimethylsilyl)withaferin A
27-O-(tert-Butyldimethylsilyl)withaferin A (compound 9a), a natural withanolide, is an apoptosis inducer. 27-O-(tert-Butyldimethylsilyl)withaferin A shows antiproliferative activity against HeLa, A-549 and MCF-7 human cancer cell lines, and against normal Vero cells[1].