Background: Achillea talagonica (Asteraceae) is an endemic herbaceous plant in Iran with small yellow flowers and several times pinnately divided leaves in worm shape. The plant was found to be cytotoxic in our previous studies.Materials and Methods: A. talagonica was collected in May 2005 from Talegan in north of Iran during the full flowering stage. Dried aerial parts of the plant were reduced in to small pieces and percolated with ethyl acetate for 72 hours. The extract obtained was filtered and then concentrated under reduced pressure and completely dried by a freeze dryer. Column chromatography of the extract on silica gel and sephadex LH-20 yielded in isolation of three main components. Cytotoxic activity was evaluated against the Artemia salina larvae by the Brine Shrimp Cytotoxicity Bioassay.Results: Isolated compounds were identified as b-sitosterol (1), salvigenin (5- hydroxy 4', 6, 7- three methoxy flavone) (2) and santoflavon (5- hydroxy 4', 3', 6, 7- tetra methoxy flavone) (3). NMR data of all the isolated compounds showed good agreement with literature data.Conclusions: In our previous studies ethyl acetate extract of A. talagonica showed cytotoxic activity in brine shrimp lethality assay. The results of BST assay indicated that only santoflavone (3) showed a good cytotoxic activity (LC50=15 mg/ml) against A. salina larvae so this compound seems to be responsible for the extract toxicity of A. talagonica against Artemia nauplii.

Five flavonoid glycosides were isolated from then -butanol soluble fraction of the ethanolic extract of Rapistrum rugosum and their structures were assigned from 1H- and 13C-NMR spectra (DEPT) with 2D NMR as quercetin-3- O-a-L-rhamnopyranoside (1), quercetin-3- O-b-D-xyloside (2), quercetin, 3-O-a- L-arabinopyranoside, 7- O-a-L-rhamnopyranoside (3), kaempferol 3- O-a-L-arabinopyranoside, 7- O-a-L-rhamnopyranoside (4) and rutin (5). The SRB cytotoxic assay was used to investigate the antitumor activities of n -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 IC50 (concentration of compound required to reduce cell survival by 50%) 0.86 mg/mL and 3.50 mg/mL, respectively. These results proved that compound 3, the major flavonoid of the n -butanol soluble fraction, has significant cytotoxic activity compared with the standard antitumor drug doxorubicin (0.60 mg/mL).