Interaction of flavones from the roots of Scutellaria baicalensis with thebenzodiazepine site

A radioreceptor binding assay was used to guide the isolation of four chemi cal constituents in the organic solvent extracts of Scutellaria baicalensis Georgi capable of binding to the benzodiazepine site (BZD-S) of the GABA(A ) receptor: wogonin (K-i = 2.03 +/- 0.24 mu M), baicalin (K-i = 77.10 +/- 4 .79 mu M), baicalein (K-i = 5.69 +/- 0.95 mu M), and scutellarein (K-i = 12 .00 +/- 1.27 mu M) All four compounds contain the flavonoid phenylbenzopyro ne nucleus. Based on BZD-S binding, the order of affinity among these four compounds was wogonin > baicalein > scutellarein > baicalin.