Abstract: A sensitive RP-HPLC-UV method has been developed and validated for the quantification of daphnoretin in rat plasma. Daphnoretin was extracted from rat plasma by protein precipitation and liquid-liquid extraction. Separation was performed on a Diamonsil C18 column (200 mm×4.6 mm, 5 μm) with a mobile phase of methanol-20 mmol/L ammonium acetate (adjusted to pH 3.2 with acetic acid, 42:58, v/v) at a flow rate of 1.0 mL/min. The UV detector was set at 345 nm and column temperature was set at 40 °C. The calibration curves were linear over the concentration range of 0.020-2.00 μg/mL. The lower limit of quantification (LLOQ) of daphnoretin in rat plasma was 0.020 μg/mL. The intra- and inter-day relative standard deviation (RSD) for measurement of quality control (QC) samples (0.050, 0.200 and 1.60 μg/mL) ranged from 5.0%-10.6%. Relative error (RE) was from ±(1.2%-2.5%). The validated method was used successfully in a pharmacokinetic study of daphnoretin in rats after intraperitoneal injection.

Key words: HPLC, Pharmacokinetic study, Daphnoretin, Rat plasma