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.

Pharmacology

Baicalein, along with its glucuronide baicalin, is a positive allosteric modulator of the benzodiazepine site and a non-benzodiazepine site of the GABAA receptor, but with an affinity over 250× lower than diazepam. It displays subtype selectivity for α2 and α3 subunit-containing GABAA 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.