Baicalein (5,6,7-trihydroxyflavone) is a flavone, a type of flavonoid, originally isolated from the roots of Scutellaria baicalensis and Scutellaria lateriflora. It is also a constituent of Oroxylum indicum (Indian trumpetflower) and thyme. It is the aglycone of baicalin.
Baicalein, along with its glucuronide baicalin, is a positive allosteric modulator of the benzodiazepine site and a non-benzodiazepine site of the GABA<sub>A</sub> receptor, but with an affinity over 250àlower than diazepam. It displays subtype selectivity for ñ<sub>2</sub> and ñ<sub>3</sub> subunit-containing GABA<sub>A</sub> receptors.
The flavonoid has been shown to inhibit certain types of lipoxygenases.
Baicalein is an inhibitor of CYP2C9, an enzyme of the cytochrome P450 system that metabolizes drugs in the body.
A derivative of baicalin is a known prolyl endopeptidase inhibitor.