Secondary Metabolites from Astragalus lycius and Their Cytotoxic Activities

Eight known secondary metabolites were isolated from the methanolic extract of the whole plant of Astragalus lycius Boiss. They were identified as 5,5'-dihydroxy-3'-methoxy-isoflavone-7-O-beta-D-glucoside (1), genistin (2), sissotrin (3), 5,4'-dimethoxy-isoflavone-7-O-beta-D-glucopyranoside (4), (7S,8R)-5-methoxydehydrodiconiferyl alcohol-4-O-beta-D-glucopyranoside (5), 4-O-lariciresinol-glucoside (6), 2-phenylethyl-beta-D-glucopyranoside (7) and beta-isitosterol-3-O-beta-D-glucopyranoside (8) by spectroscopic methods including H-1- and C-13-NMR and HR-MS experiments, and by comparison with literature values. Compounds 1-7 are reported for the first time from Astragalus taxa. All of the compounds were tested for their cytotoxic activities against a number of cancer cell lines. Among them, only 6 exhibited significant activity against human colon carcinoma (HT-29) at 2.69 mu M concentration.