[Analysis of main flavonoids contents of Scutellaria baicalensis].

OBJECTIVE: To develop a HPLC-DAD method for simultaneous determination of six flavonoids in Scutellaria baicalensis, and study the effect of geographic sources, culturation, harvesting time and processing on the contents of flavonoids. METHOD: The analysis was performed on a Thermo ODS-2 Hypersil column (4.6 mm x 250 mm, 5 microm) at 26 degrees C with a gradient program of acetonitrile-0.1% H3 PO4 aqueous solution-tetrahydrofuran as the mobile phase and a Diode Array Detector as the detector with the detection wavelength at 274 nm. The flow rate was 1.0 mL x min(-1), and the injection value was 20 microL. RESULT: Six flavonoids, baicalin (1), oroxylin A-7-O-glucuronide (2), wogonoside (3), baicalein (4), wogonin (5) and oroxylin A (6), were linear over the selected range with R2 > or = 0.999 3. The average recoveries were between 96.6% -103.0%, and RSD were less then 5.0% (n = 9) for flavonoids 1-6. By analyzing the data obtained, the effect of geographic sources, culturation, harvesting time and processing on the contents of flavonoids were discussed. CONCLUSION: This method is simple, sensitive, reliable and reproducible. It can be used for the quality control of S. baicalensis.