Effect of glycyrrhizic acid on the bioavailability of resveratrol

In this study, the effect of glycyrrhizic acid, a natural bio-enhancer, on the oral bioavailability of resveratrol, a natural and useful phytosterol, was investigated. Bioavailability study was performed on 12 male Oryctolagus cuniculus New Zealand White rabbits. One group of rabbits received 100 mg/kg resveratrol and 100 mg/kg resveratrol and 100 mg/kg glycyrrhizic acid. The rabbits were 0; 2.5; 5; 10; 15; 30 minutes and 1; 2; 4; 6; 8; 10; 24 hours blood was collected and plasmas were obtained. A new HPLC-FL method was developed for the analysis of the samples. In the sample preparation of the method, mobile phase precipitation was used and the amount of resveratrol in the plasma was measured in the C18 column (250 x 4,6 mm, 5 µ i.d.) by isocratic application of acetonitrile-0.2% formic acid (35:65) mobile phase system with 30°C was analyzed at a flow rate of 1 mL/min. Excitation and emission wavelengths were determined as 320 nm and 400 nm, respectively, and quercetin was used as the internal standard in the method. The validation of the developed method was performed according to ICH rules. The calibration curve showed a linearity of 10-800 ng/mL and LOD and LOQ values were determined as 2,17 ng/mL and 7,25 ng/mL, respectively. In the plasma samples studied, Cmax values of resveratrol and resveratrol combined with glycyrrhizic acid were 100,14 ng/mL and 270,16 ng/mL, respectively; The AUC0-∞ olarak values were 8,97 ng.h/mL and 38,59 ng.h/mL, respectively. When the pharmacokinetic data were compared with each other, the increase in AUC0-∞ and Cmax values obtained from the combination of resveratrol with glycyrrhizic acid was 430% and 270%, respectively. These values showed us that glycyrrhizic acid significantly increases the bioavailability of resveratrol.