[Development and validation of method for the determination of cynarin, luteolin in plasma]

The aim of this study was to develop and validate the method of cynarin and luteolin, the main constituents of artichoke (Cynara scolymus L.) leaf extract, determination in plasma. The compounds were separated using the high-performance liquid chromatography technique with diode array detection (HPLC-DAD). The analysis was preceded by liquid-liquid extraction using as the extracting agent ethyl acetate. The HPLC separation was performed on C18 column under gradient conditions using a mobile phase - 0,05% trifluoroacetic acid in water and methanol. The detector was set at lambda=330 nm. The validation was related to linearity, sensitivity (LOD and LOQ), accuracy and repeatability. In the validated method the linearity was achieved within concentration range 1,5625 - 50,0 microg/cm3 for the cynarin (R2=0,9989) and 1,5625 - 200,0 microg/cm3 for the luteolin (R2=0998). The limits of detection for cynarin and luteolin was: 0,75 microg/cm3 and 0,1 microg/cm3 and the limits of quatification: 2,25 microg/cm3 and 0,2 microg/cm3, respectively. Coefficient of variation for the inter-day and the intra-day analysis, which is a precision and accuracy parameter, do not exceed 10%. Recovery was 67% for the cynarin and 96% for the luteolin. The practical application of this method was proved by analysis of plasma samples from rats. The animals were administrated artichoke leaf extract - orally and intraperitoneally at a dose of 3 g/kg body weight or pure substances - intraperitoneally at a dose 1 mg/kg of luteolin and 0,5 mg/kg of cynarin. The presence of investigated compounds was proved only in samples after intraperitoneal administration of pure substances. The developed method is used to determine simultaneously cynarin and luteolin, after intraperitoneal administration of pure compounds.