HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY OF THYMOQUINONE IN RABBIT PLASMA AND ITS APPLICATION TO PHARMACOKINETICS

The chemical compound thymoquinone (THQ) isolated from Nigella sativa seed oil has multiple therapeutic potentials. A simple and rapid reversed-phase high-performance liquid chromatography assay was developed to determine the concentration of THQ in rabbit plasma. The procedure involved extraction of the compound and thymol (internal standard) from the plasma using acetonitrile and methanol. The extract was injected onto Waters 5 mu m Atlantis dC-18 Bond pack column (10 , 150x3.9mm 1.d.). The mobile phase consisted of methanol and 10mM KH2PO4 buffer in the ratio of 90:10 (v/v, pH=4.6), which was delivered using isocratic flow at a rate of 0.9mL/min. THQ and the internal standard were monitored using UV detection at 254nm with a total run time of 7min. The method was found to be linear (r(2)>0.997), precise (CVs=3.69-12.63%) and accurate (recovery=88-107.77%) in the concentration range of 0.5-50 mu g/mL. The limits of detection and quantitation of the method were 0.134 and 0.408 mu g/mL, respectively. The within and between-day coefficients of variation were less than 7%. The method has been successfully used to measure THQ plasma concentrations in a rabbit model following an intravenous administration of the drug.