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 reported in Oroxylum indicum (Indian trumpetflower) and Thyme.[1] It is the aglycone of baicalin. Baicalein is one of the active ingredients of Sho-Saiko-To, which is a Chinese classic herbal formula, and listed in Japan as Kampo medicine.[citation needed]
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Other names | Biacalein; Noroxylin |
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UNII |
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ECHA InfoCard | 100.164.911 |
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Formula | C15H10O5 |
Molar mass | 270.240 g·mol−1 |
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Baicalein, along with its glucuronide baicalin, is a positive allosteric modulator of the benzodiazepine site and/or a non-benzodiazepine site of the GABAA receptor but with an affinity over 250× lower than diazepam.[2][3][4][5][6][7] It displays subtype selectivity for α2 and α3 subunit-containing GABAA receptors.[8] In accordance, baicalein shows anxiolytic effects in mice without incidence of sedation or myorelaxation.[7][8][9] It is thought that baicalein, along with other flavonoids, may underlie the anxiolytic effects of S. baicalensis and S. lateriflora.[10][11] Baicalein is also an antagonist of the estrogen receptor, or an antiestrogen.[11]
The flavonoid has been shown to inhibit certain types of lipoxygenases[12] and act as an anti-inflammatory agent.[13] It has antiproliferative effects on ET-1-induced proliferation of pulmonary artery smooth muscle cell proliferation via inhibition of TRPC1 channel expression.[14] Possible antidepressant effects have also been attributed to baicalein in animal research.[15]
Baicalein is an inhibitor of CYP2C9,[16] an enzyme of the cytochrome P450 system that metabolizes drugs in the body.
A derivative of baicalin is a known prolyl endopeptidase inhibitor.[17]
Baicalein has been shown to inhibit Staphylococcus aureus biofilm formation and the quorum sensing system in vitro.[18]
It has also been shown to be effective in vitro against all forms of Borrelia burgdorferi and Borrelia garinii.[19]