Isolation and Identification of 6-Methylapigenin, a Competitive Ligand for the Brain GABAAReceptors, fromValeriana wallichii

Using the guidance by a competitive assay for the benzodiazepine binding site in the GABA A receptor, active compounds were isolated from the rhizomes and roots of Valeriana wallichii DC. The UV, NMR and mass spectral data permitted the identification of 6-methylapigenin. This flavonoid has a Ki = 495 nM for the BDZ-bs and a GABA ratio of 1.6 - 2.0, which suggests possible agonistic properties. The calculated percentage of 6-methylapigenin in the crude drug is in the range: 0.013 % to 0.0013 %. Abbreviations BDZ-bs:benzodiazepine binding site GABA ratio:gamma amino butyric acid ratio GABA A :gamma amino butyric acid type A receptor 3 H-FNZ:tritium flunitrazepam Ki:inhibition constant