ABSTRACT
Eight known secondary metabolites were isolated from the methanolic extract of the whole plant of Astragalus lycius Boiss. They were identified as 5,5'-dihydoxy-3'-methoxy-isoflavone-7-0-ß-D-glucoside (1), genistin (2), sissotrin (3), 5,4'-dimethoxy-isoflavone-7-0-ß-D-glucopyranoside (4), (7S,8R)-5-methoxydehydrodiconiferyl alcohol-4-0-ß-D-glucopyranoside (5), 4-0-lariciresinol-glucoside (6), 2-phenylethyl-ß-D-glucopyranoside (7) and ß-sitosterol-3-O-ß-D-glucopyranoside (8) by spectroscopic methods including (1)H- and (13)C-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 µM concentration.
Subject(s)
Antineoplastic Agents , Astragalus Plant/metabolism , Phytochemicals , Antineoplastic Agents/analysis , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Cell Line , Cell Survival/drug effects , Humans , Phytochemicals/analysis , Phytochemicals/metabolism , Phytochemicals/pharmacology , Secondary MetabolismABSTRACT
One hundred and twenty-six mesophilic Actinomycete cultures were isolated from the Aegean region of Turkey. The antimicrobial activities of pure isolates were tested using the agar-plaque method. Based on high antimicrobial activity against methicillin resistant Staphylococcus aureus (MRSA) and Escherichia coli O157-H7 (E. coli), the isolate M-33-5 was selected for bioactivity-guided isolation. Fermentation, followed by solvent partition (H2O-EtOAc, H2O-n-BuOH), showed that the highest activity was present in the EtOAc extract. By using chromatographic methods, two bioactive compounds were isolated and their structures were determined by spectral methods to be 4'-deacetyl griseusin A and griseusin A. The MIC values of griseusin A and 4'-deacetyl griseusin A against MRSA and E. coli were < or = 1.0 microg/mL. The cytotoxicities of the EtOAc extract and 4'-deacetyl griseusin A were also evaluated against two cancer cell lines (human servical cancer: HeLa; murine fibroblastic cells: L-929). The EtOAc extract showed strong cytotoxic activity against HeLa and L-929 lines with IC50 values of 1.57 and 2.43 microg/mL, respectively, whereas 4'-deacetyl griseusin A was very potent with IC50 values of 0.43 versus HeLa, and 0.12 microg/mL against L-929. The active strain M-33-5 was identified as Streptomyces griseus by 16SrDNA sequence data.
