Daturametelins H, I, and J: three new withanolide glycosides from Datura metel L

Three new withanolide glycosides named daturametelins H-J (1-3), together with two known ones, daturataturin A (4) and 7,27-dihydroxy-1-oxowitha-2,5,24-trienolide (5), were isolated from the MeOH extract of the aerial parts of Datura metel L. (Solanaceae). Their structures were determined mainly by spectroscopic techniques including 2D-NMR (HMBC, HMQC, (1)H,(1)H-COSY, NOESY) and MS experiments. Compounds 1-5 were tested for their antiproliferative activity towards the human colorectal carcinoma (HCT-116) cell line. The nonglycosidic compound 5 exhibited the highest activity of the tested withanolides, with an IC(50) value of 3.2+/-0.2 microM (Table 3).