Baicalein

Baicalein is a plant flavone, chemically 5,6,7-trihydroxyflavone, belonging to the broad family of flavonoid polyphenols. It was first isolated from the roots of Scutellaria baicalensis, the Baikal or Chinese skullcap, and it also occurs in the related Scutellaria lateriflora, in Oroxylum indicum (the Indian trumpet flower), and in some other plants ^[1]. Scutellaria baicalensis root, known as Huang Qin in traditional Chinese medicine, has been used for centuries, and baicalein together with baicalin and wogonin is among the flavones that give the herb its characteristic activity ^[1].

Baicalein is closely tied to baicalin, its 7-O-glucuronide; baicalin is essentially baicalein carrying an attached glucuronic acid group ^[1]. The two forms interconvert in the body, since baicalin can be hydrolyzed to baicalein for absorption and baicalein can be conjugated back to baicalin, a relationship that shapes how the compound is taken up and distributed ^[1]. The three neighboring hydroxyl groups on baicalein's structure give it strong metal-binding and free-radical-scavenging properties, which underlie much of its antioxidant behavior ^[2].

Most of what is known about baicalein comes from laboratory and animal studies rather than large human trials. It is a potent inhibitor of lipoxygenase enzymes, blocking both platelet 12-lipoxygenase and reticulocyte 15-lipoxygenase, actions relevant to inflammation ^[2]. It has been shown to inhibit indoleamine 2,3-dioxygenase, an enzyme implicated in immune regulation and neurodegeneration, and in the same work it encouraged neurite outgrowth in human neural stem cells ^[3]. Reviews of skullcap flavones highlight baicalein's neuroprotective activity, including reduction of oxidative stress, interference with the protein aggregation seen in Alzheimer's and Parkinson's disease models, and anticonvulsant, anxiolytic, and mild sedative effects in animals ^[1]. Baicalein has additionally been studied for antiviral, anticancer, and metabolic effects, though these remain preclinical ^[1].

Baicalein is not an approved drug in most jurisdictions and is met primarily as a research compound and as a constituent of skullcap extracts sold as botanical supplements ^[1]. It is available in purified form for laboratory use and appears in some dietary products, but its value in humans has not been established through rigorous clinical trials ^[1].

Generally well tolerated in studies, with mild GI effects the most common. It can inhibit some drug-metabolizing enzymes and affect clotting, so caution is warranted with anticoagulants and other medications. As with many flavonoids, thorough long-term human safety data is limited. Pregnancy safety isn't established.