Cytotoxic flavonoid glycosides from rapistrum rugosum l

Five flavonoid glycosides were isolated from the-butanol soluble fraction of the ethanolic extract of Rapistrum rugosum and their structures were assigned from 'H- and [13]C-NMR spectra [DEPT] with 2D NMR as quercetin-3-[9-a-L-rhamnopyranoside [1], quercetin-3-<9-/?-D-xyloside [2], quercetin, 3-0-a-L-arabinopyranoside, 7-0-a-L-rhamnopyranoside [3], kaempferol 3-0-a-L-arabinopyranoside, 7-0-a-L-rhamnopyranoside [4] and rutin [5]. The SRB cytotoxic assay was used to investigate the antitumor activities of "-butanol extract, compound 3 and its hexaacetate 3a, for the first time. Compounds 3 and 3a showed cytotoxic activity against the human cancer cell line, namely, HepG2 [hepatocellular carcinoma cell line] with IC[50] [concentration of compound required to reduce cell survival by 50%] 0.86 microg/mL and 3.50 microg/mL, respectively. These results proved that compound 3, the major flavonoid of the ft-butanol soluble fraction, has significant cytotoxic activity compared with the standard antitumor drug doxorubicin [0.60 microg/mL]