Plasma liquid chromatographic analysis and investigation bioavailability of some diterpenoid compounds in rosmarinus species

In this study high performance liquid chromatographic (HPLC) methods have been developed in order to determine two diterpenoid compounds called carnosol and carnosic acid in human plasma, which are subjected to scientific studies due to mainly anticarcinogenic and other several medical effects and which are found in the species of Lamiaceae family but mainly in Rosmarinus species. For this purpose the analytes, that are extracted from plasma by liquid-liquid extraction technique, separated with reverse phase chromatography, C18 (250 mm × 4.6 mm × 5 μm) column and a mobile phase composed of methanol-%2 o-phosphoric acid using gradient elution profile with a flow rate 1.2 mL/min for carnosol and with C18 (150 mm × 4.6 mm × 5 μm) column and methanol-%2 o-phosphoric acid (90:10 (v/v)) mixture as mobile phase with isocritical flow and 1 mL/min flow rate for carnosic acid. Both of the analytes have been detected by UV dedection at 230 nm. The developed methods have been validated according to ICH criteria in the terms of selectivity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), robustness and stability. The linearity and the correlation coefficient of the linearity equation for carnosol and carnosic acid methods are 1-20 ng/mL and 0.25-8 ng/mL and 0.9942 and 0.9906, respectively. The RSD % values for carnosol and carnosic acid methods are 5.71 and 5.13, respectively. Additionally, both compounds have been collected by preparative HPLC and their qualitative analysis have been performed by LC - tandem mass spectrometry combination and IR spectrometry. The developed methods have been applied to healthy volunteer following oral administration of the extract of Rosmarinus officinalis L. and the methods have been used to determine the pharmacokinetic parameters such as Cmax, tmax, t1/2 and AUC0-t, AUC0-∞.