Determination of aglycone conjugated metabolites of scutellarin in rat plasma by HPLC.

A specific, precise and accurate high-performance liquid chromatography (HPLC) method for the determination of aglycone conjugated metabolites of scutellarin in plasma after enzymolysis to scutellarein (the aglycone of scutellarin) was developed and validated. The chromatographic separation was performed on a Lunar C18(2) reversed-phase column at a column temperature of 40 degrees C. The mobile phase, delivered at 1.0 ml/min, consisted of acetonitrile-KH2PO4 buffer (40 mM, pH 2.5) (33:67, v/v). The detection wavelength was set at 335 nm. Scutellarein and I.S. (quercetin) were isolated by a liquid-liquid extraction after incubating the plasma samples with beta-glucuronidase/sulfatase. The method was validated using scutellarin spiked plasma as standards. Linearity was confirmed in the concentration range of 0.2165-4.329 nmol/ml, R.S.D.s were within 8.32%, and the recoveries of scutellarein ranged from 101.2 to 108.6%. The method is applicable to the pharmacokinetic study of aglycone conjugated metabolites of scutellarin in rats after oral administration of scutellarin.