Baicalein (5,6,7-trihydroxyflavone) is a

flavone Flavone is an organic compound with the formula . A white solid, flavone is a derivative of chromone with a phenyl (Ph) substituent adjacent to the ether group. The compound is of little direct practical importance, but susbstituted derivatives, t ...

, a type of

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

, originally isolated from the roots of '' Scutellaria baicalensis'' and '' Scutellaria lateriflora''. It is also reported in ''

Oroxylum indicum ''Oroxylum indicum'' is a species of flowering plant belonging to the monotypic genus ''Oroxylum'' and the family Bignoniaceae, and is commonly called Indian trumpet tree, oroxylum, Indian trumpet flower, broken bones, Indian caper, scythe tree o ...

'' (Indian trumpetflower) and '' Thyme''. It is the aglycone of

baicalin As baicalin is a flavone glycoside, it is a flavonoid. It is the glucuronide of baicalein. Natural occurrences Baicalin is found in several species in the genus ''Scutellaria'', including '' Scutellaria baicalensis'', and '' Scutellaria late ...

. Baicalein is one of the active ingredients of Sho-Saiko-To, which is a

Chinese classic herbal formula Chinese classic herbal formulas () are combinations of herbs used in Chinese herbology for supposed greater efficiency in comparison to individual herbs. They are the basic herbal formulas that students of Traditional Chinese medicine learn. Later t ...

, and listed in Japan as Kampo medicine. As a Chinese herbal supplement, it is believed to enhance liver health. Baicalein, along with its analogue baicalin, is a positive allosteric modulator of the benzodiazepine site and/or a non-benzodiazepine site of the GABA_A receptor. It displays subtype selectivity for α₂ and α₃ subunit-containing GABA_A receptors. In accordance, baicalein shows anxiolytic effects in mice without incidence of

sedation Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure. Examples of drugs which can be used for sedation include isoflurane, diethyl ether, ...

myorelaxation A muscle relaxant is a drug that affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeu ...

. It is thought that baicalein, along with other flavonoids, may underlie the anxiolytic effects of ''S. baicalensis'' and ''S. lateriflora''. Baicalein is also an

antagonist An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, riv ...

of the estrogen receptor, or an antiestrogen. The flavonoid has been shown to inhibit certain types of lipoxygenases and act as an anti-inflammatory agent. It has antiproliferative effects on ET-1-induced proliferation of pulmonary artery smooth muscle cell proliferation via inhibition of TRPC1 channel expression. Possible antidepressant effects have also been attributed to baicalein in animal research. Baicalein is an

inhibitor Inhibitor or inhibition may refer to: In biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotra ...

of CYP2C9, an enzyme of the

cytochrome P450 Cytochromes P450 (CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are ...

system that metabolizes

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

s in the body. A derivative of baicalin is a known prolyl endopeptidase inhibitor. Baicalein has been shown to inhibit ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...

'' biofilm formation and the quorum sensing system in vitro. It has also been shown to be effective '' in vitro'' against all forms of '' Borrelia burgdorferi'' and '' Borrelia garinii''.

Glycosides

Tetuin Tetuin is a flavone, a type of flavonoid. It is the 6-O-glucoside of baicalein. It can be isolated from the seeds of ''Oroxylum indicum ''Oroxylum indicum'' is a species of flowering plant belonging to the monotypic genus ''Oroxylum'' and the f ...

is the 6-

glucoside A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes. The name was o ...

of baicalein.

References

{{Leukotrienergics Aromatase inhibitors Flavones Pyrogallols GABAA receptor positive allosteric modulators Antiestrogens Anxiolytics

Glycosides

See also

References