Baicalin

Baicalin is one of the main active ingredients obtained from the roots of huang qin (Scutellaria baicalensis Georgi). The Pharmacopoeia of the People’s Republic of China (2015) stipulates that the content of baicalin in radix scutellariae with dry goods shall not be less than 9.0%. The medicinal radix scutellariae distribution in China are now Yunnan radix scutellariae (S. amoena C.?H. Wright), sticky hairs radix scutellariae (S. viscidula Bunge), Gansu radix scutellariae (S. rehderiana Diels), Lijiang radix scutellariae (S. likiangensis Diels), Sichuan radix scutellariae (S. hypericifolia Lev l.), radix scutellariae (S. tenax W.?W. Smith var. patentipilosa G.? Y. Wu), etc., which contain a certain amount of baicalin. Radix scutellariae medicinal has a long history in China. Listed as goods in Shen Nong’s Classic of Materia Medica, it has been used clinically to treat diseases with symptoms such as “heat jaundice, intestinal dysentery, edema, amenorrhea, malignant sore, and scleritis” for about 2000? years. Scutellaria is recorded in the Pharmacopoeia of the People’s Republic of China to have the effects of “clear heat and wet, purging fire to detoxify, stop bleeding and tocolysis.” It is one of the commonly used traditional Chinese herbs, which is clinically used alone or with other Chinese medicine compatibility for the treatment of respiratory infections, acute dysentery, viral hepatitis, allergic disease and gynecological disease, and so on.

Light yellow powder

Appearance: light yellow crystalline powder at room temperature. Solubility: insoluble in methanol, ethanol, and acetone; slightly soluble in chloroform and nitrobenzene; almost insoluble in water; soluble in hot acetic acid. Melting point: 202–205?°C.

The chemical research of the genus Scutellaria began in 1889. Baicalein (scutellarein) is the first flavonoid isolated from Vietnam radix scutellariae (S. altissima) in 1910. In 1922, Shibata Gui Tai and his collaborators isolated and obtained baicalin, baicalein, wogonin, and benzoic acid from Scutellaria baicalensis.
Among the flavonoids in Scutellaria baicalensis, the content of baicalein is the highest. Its official name is baikeli. Baicalin is formed by the combination of baicalein and one molecule of glucuronic acid. Both baicalein and baicalin exist in Scutellaria baicalensis. Studies showed that baicalein could be transferred into baicalin and other metabolites in the blood. However, baicalin by oral is hardly absorbed. Baicalein can be absorbed and also rapidly converted into baicalin.
At present, there are a variety of mature extraction methods for obtaining baicalin and baicalein from Scutellaria baicalensis. Due to the poor water solubility, oral preparation of baicalin is mostly used in clinical practice. Research showed that baicalin had a significant first pass effect, which led to its low bioavailability. Baicalin-metal complexes formed by the combination of baicalin and metal ions were found to enhance bioavailability and increase pharmacological activities. In addition, the preparation of ester-type prednisone was easily hydrolyzed by esterase and could improve the lipid solubility of baicalin.

Baicalin has been used in a study to examine its neuroprotective effect in chronically stressed rats.2

Baicalin is mainly used for the adjuvant therapy of acute and chronic hepatitis and persistent hepatitis.

ChEBI: The glycosyloxyflavone which is the 7-O-glucuronide of baicalein.

Baicalin is a key flavonoid found in the roots of Scutellaria baicalensis. It is known to have different biological activities, such as anti-oxidative, anti-inflammatory, antitumor and anti-apoptotic activities.

In clinical, baicalin is mainly used as the adjuvant therapy for acute and chronic hepatitis and persistent hepatitis. Baicalin was shown to reduce the expression of hepatitis B surface antigen, e antigen and the core antigen, and inhibited hepatitis B virus DNA replication. Reduced serum alanine aminotransferase level was observed in hepatitis patient treated with baicalin, and other liver function indexes were also found to be improved. No adverse reactions about baicalin have been reported. In addition, baicalin was reported to treat early diabetic nephropathy and alleviate the symptoms of diabetic neuropathy
As one of the antimicrobial components of Scutellaria baicalensis, eye drops containing 3% baicalin are used clinically in the treatment of trachoma, with the similar curative effect as rifampicin.
Moreover, baicalein is used clinically for the treatment of enteritis and dysentery.

This baicalein glucuronide (FW = 446.36 g/mol; CAS 21967-41-9), also known as 5,6-dihydroxy-4-oxygen-2-phenyl-4H-1-benzopyran-7-b-D glucopyranose acid, is a flavone prodrug found in the Chinese medicinal herb Huang-chin (Scutellaria baicalensis) that is hydrolyzed to baicalein (See Baicalein). Baicalin is a slow, tight-binding inhibitor of Jack Bean urease, rapidly forming initial BA-urease complex (Ki = 3.9 × 10–3 M) that slowly isomerizes to the final complex (overall inhibition constant of Ki* = 0.15 × 10 μM. Inhibition can be reversed by dithiothreitol but not dilution of substrate. Baicalin also inhibits prolyl oligopeptidase, a cytosolic serine peptidase that hydrolyzes proline-containing peptides at the carboxy terminus of proline residues and is associated with schizophrenia, bipolar affective disorder, and related neuropsychiatric disorders. (See Pramiracetam)