Pharmacokinetics of luteolin and tetra-acetyl-luteolin assayed by HPLC in rats after oral administration.

Accurate and reproducible HPLC methods were developed and validated for the determination of concentrations of luteolin (LT) and tetra-acetyl-luteolin (TALT) in rat plasma. HPLC analyses were performed on an Agilent TC-C(18) column protected by a guard Agilent Zorbax Eclipse Plus. The mobile phase for LT was a binary mixture of acetonitrile-water (40:60, v/v) containing 0.5% phosphoric acid at a flow rate of 1.0 mL/min, and that for TALT was a binary mixture of methanol-water (70 : 30, v/v) containing 0.5% glacial acetic acid at the same flow rate. The UV detection wavelength for both analytes was set at 350 nm. The calibration curve was linear over the range of 40-1800 ng/mL, the lower limit of quantitation was 40 ng/mL and the lower limit of detection was 20 ng/mL for both LT and TALT. The intra- and inter-day precision (RSD) values for all samples were within 7.9%. The concentration-time curves of LT and TALT after oral administration (30 mg/kg) were both fitted to a two-compartment model. The pharmacokinetic characteristics of TALT were better than that of LT in the maximum plasma concentration (C(max)) and the area under the concentration-time curve (AUC).