Abstract
Three flavonoid glycosides and one aglycone were isolated from the ethanol extract (EE) of Horwoodia dicksoniae (Brassicaceae), for the first time, and their structures were established from negative ESI-MS, H-1-, C-13-NMR and DEPT as luteolin 7-O-beta-D-glucopyranoside (1), luteolin 6-C-beta-D-galactopyranoside (2), apigenin 6-C-beta-D-galactopyranoside (3) and luteolin (4). The SRB cytotoxicity assay was used to investigate the antitumor activity of the EE, Compounds 1, 2 and 4. Compound 1 showed the highest cytotoxic activity against the three human cell lines, including HEP-G2, HCT-116 and MCF-7 (IC50 = 10.7, 9.3 and 9.9 mu g/ml, respectively), compared with doxorubicin as reference drug. Compound 4 showed selective antitumor activity against the colon cell line (IC50 = 9.5 mu g/ml). The present investigation also demonstrates the protective effect of Compounds 1, 2 and 4 with strong antioxidant potential, in glycerol-induced myoglobinuric acute renal failure in rats. Moreover, all tested compounds separately attenuated renal dysfunction, and restored the oxidant balance by decreasing renal MDA levels, increasing the activity of the depleted renal antioxidant enzymes, and the non enzymatic antioxidant GSH. They also, decreased the elevated serum inflammatory marker (TNF-alpha), and ameliorated apoptotic kidney damage by reduction in caspase-3 activity. Taken together, 1 was found to be the most biologically active compound.