Baicalin

BeschreibungBaicalin 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.

HistoryThe 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.