New phenolic compounds from the seeds of Nigella glandulifera and their inhibitory activities against human cancer cells.

Four phenolic compounds, including two new ones, Nigephenol A and B (1-2), and a new natural product, Nigephenol C (3), were isolated from the seeds of Nigella glandulifera. Their structures were elucidated on the basis of spectroscopic analyses using HR-ESI-MS, 1D and 2D NMR spectra. All compounds were evaluated by MTT method for in vitro cytotoxicity against four human cancer cell lines (Bel7402, HepG2, HCT-8 and A549). The results revealed that Compounds 1-4 showed more selective activities against HepG2 cells, and that Compound 2 showed significant inhibitory effects against four human tumor cell lines with IC50 values comparable to those of 5-fluorouracil.