Cytotoxic withanolides from Datura innoxia

Chemical investigation of the aerial parts (except fruits) of the medicinal, hallucinogen and toxic plant Datura innoxia Mill. [Solanaceae] led to the isolation of the new withanolide, dinnoxolide A (1), along with the known compounds 21,27-dihydroxy-1-oxowitha-2,5,24-trienolide (2), daturamalakin B (3) and withametelin (4). Their structures were established by analysis of their spectroscopic data, including 1D and 2D NMR experiments and MS. Compounds 2 and 3 were isolated as natural products for the first time and the name dinnoxolide B was given to compound 2. The four withanolides showed in vitro cytotoxic activity against U251 (glioblastoma) and SK-LU-1 (lung adenocarcinoma) human cancer cell lines, with IC₅₀ values ranging from 1.2 to 19.6 µM, and also against the noncancerous monkey kidney cell line (COS-7), with IC₅₀ values ranging from 5.0 to 19.7 µM. Compound 4 was two times more active than the reference compound, etoposide, against lung adenocarcinoma cells.