Cytotoxic Cardiac Glycoside from the Parasitic Plant Cuscuta reflexa.

Bioassay guided fractionation of the cytotoxic extract of the plant Cuscuta reflexa, employing cytotoxic assay against a panel of 60 cell lines, led to the isolation of 13 compounds identified as odoroside H ( 1), 21-hydroxyodoroside H ( 2), neritaloside ( 3), strospeside ( 4), 16- β-hydroxydigitoxin ( 5), N-trans and cis feruloyl tyramines ( 6 and 7), ethyl caffeate ( 8), coumarins ( 9 and 10), ursolic acid ( 11), β-sitosterol glucoside ( 12), and 4-O-p-coumaroyl- β-D-glucoside ( 13). Compound 2 was found to be a new natural product while 1, 3, 4, 5, 6, 7, 10, and 11 are known compounds isolated from this source for the first time. Compounds 1, 3, and 4 possessed very good cytotoxic activity against renal and prostate cancer cell lines. Of these compounds, 1 showed a positive hollow fiber test and was selected for in vivo xenograft testing. The structures of compounds 1-5 have been established through chemical and spectral studies including UV, IR, mass, NMR (H and C), and 2D NMR (COSY-45°, NOESY, HMQC, HMBC, and J-resolved) experiments. [ABSTRACT FROM AUTHOR]