Abstract
The present study was carried out to elucidate the difference in the concentration of glycyrrhizin (G) in the rat plasma and in its absorption after oral administration of licorice extract and G. The concentration of G in the plasma was determined by high performance liquid chromatography. It was found that the time required for a maximum concentration (Tmax) of G was 8 h after administration of licorice extract. On the other hand, G reached a maximum plasma concentration at less than 6 h after administration of G. The plasma level of G fell slowly within 24 h after their oral administration, and it was still detected in the plasma even after 24 h. The maximum concentration (Cmax) of G in the plasma after oral administration of licorice extract was somewhat lower than that of G. On the other hand, the area under the plasma-time curve (AUC24h) of G after oral administration of licorice extract was almost the same as that of G. The effects of licorice extract and G on excretive urine volume was also investigated in rats. Licorice extract and G, at the dose used in this experiment, did not show any effect as compared with a control group.
