Comparison of the Major Flavonoid Content of Raw and Steamed Scutellariae Radix by High-Performance Liquid Chromatography

This study was conducted to evaluate the effects of different extraction methods on the major flavonoid content of raw and steamed Scutellariae radix by applying high-performance liquid chromatography. Eight extraction methods such as extraction method in 2010 Chinese Pharmacopoeia (ChP-method), water refluxing extraction (WTRE-method), 60% ethanol refluxing extraction (ETRE-method), ultrasonic-assisted aqueous extraction (UAAE-method), ultrasonic-assisted 60% ethanol extraction (UAEE-method), cellulase-assisted solvent extraction (CASE-method), pectinase-assisted solvent extraction (PASE-method), and double-enzyme-assisted solvent extraction (DEASE-method) were investigated. The content ranges of baicalin (BG), wogonoside (WG), baicalein (BA), and wogonin (WO) in raw Scutellariae radix by using ChP-, ETRE-, UAEE-, WTRE-method were 194.91~226.50, 69.90~77.11, 33.30~68.83, and 15.83~20.40 μmol g^-1 herbals, respectively, while those by using UAAE-, CASE-, PASE-, DEASE-method were 3.81~7.17, 14.34~26.50, 134.70~227.58, and 42.92~46.79 μmol g^-1 herbals, respectively. The result showed that the effects of different extraction methods on the major flavonoid content in raw Scutellariae radix were very significant. However, the content ranges of BG, WG, BA and WO in steamed Scutellariae radix by using eight extraction methods were 196.48~239.94, 67.99~79.93, 33.30~71.42, and 9.85~22.87 μmol g^-1 herbals, respectively. Compared with raw Scutellariae radix, the effects of different extraction methods on the major flavonoid content in steamed Scutellariae radix were not significant. Based on these findings, the extraction method and the extraction solvent selected could influence the content of the bioactive flavonoids extracted from Scutellariae radix, and the processing could also do it.