Isolation and identification of 6-methylapigenin, a competitive ligand for the brain GABA(A) receptors, from Valeriana 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%.