Objective: To isolate and purify the active compounds at the benzodiazepine rec-ptor from
Artemisia herba alba. Methods:
The extracts from
Artemisia herba alba were isolated and identified by radio-receptor binding assay with HPLC methods. The chemical structures of the compounds were identified by NMR and mass spectrometry. Results: Two active compounds,dinatin and skrofulein,were got and the both inhibited the bindings of 3H-diazepam to rat brain membranes in vitro with IC50 values of (1.3±0.1) μmol/L and (22.7±2.5) μmol/L for dinatin and skrofulein
respectively. Both compounds also inhibited the binding of prazosin to α1 -adrenoceptor in vitro with value of 74 μmol/L and 700 μmol/L respectively. The GABA-ratios were 1.10 and 1.20 for dinatin and skrofulein respectively and both the compounds showed a slight increase in 35S-TBPS binding. It suggested both the compounds were antagonists or weak partial agonists. Scatchard plot analysis showed a mixed competitive and noncompetitive inhibition by both compounds. Conclusion:Both flavones are antagonists or weak partial agonists of the benzodiazepine receptors and they inhibit the binding of 3H-diazepam to rat brain membranes in vitro by a mixed competitive and noncompetitive mechanism.