Rapid estimation of glycyrrhizin and glycyrrhetinic acid in plasma by high-speed liquid chromatography.

Publisher Website
Google Scholar
Abstract
A method was established by which glycyrrhizin [G] and glycyrrhetinic acid present in [rat] plasma can be extracted with methanol and separated and determined quantitatively within 10 min by means of high-speed liquid chromatography. Using this method, G and glycyrrhetinic acid added to the plasma were recovered to satisfactory extents. An in situ recirculating perfusion technique showed that G is absorbed in rat small intestine in an apparent first-order process. There was no detectable amount of glycyrrhetinic acid in the blood after bolus injection of G into the portal vein, although glycyrrhetinic acid was present in a detectable amount in the blood after oral administration. Since it is water-soluble and has a high MW, G is probably absorbed in the small intestine in the form of glycyrrhetinic acid. With the decline of glycyrrhetinic acid in the blood, there was a rise in the blood level of a substance which exhibited the same chromatographic behavior as G. This substance appears to be a glucuronic acid conjugate formed as a metabolite of glycyrrhetinic acid, although it is not clear whether it is a mono- or diglucuronic acid conjugate or a mixture of the two. G injected into the portal vein was slowly eliminated from the blood.