HPLC determination of 18β-glycyrrhetinic acid urine excretion profile after ingestion of glycyrrhizin

Glycyrrhizin is the main pharmacologically active component in licorice. It has a pleasant aromatic sweet taste and is commonly used as flavouring and sweetening agent in confectionery, beverages, chewing gums, and tobacco products. Long term consumption of higher amounts of glycyrrhizin results in serious side effects known as the syndrome of pseudoaldosteronism, which is caused by the glycyrrhizin metabolite 3β-monoglucuronyl-18β-glycyrrhetinic acid (3-MGA). The aim of our study was to determine urine excretion profile of 3-MGA. We analyzed 18β-glycyrrhetinic acid obtained after enzymatic hydrolysis of. Six healthy volunteers ingested 0.6g of glycyrrhizin. In the first experimental period, glycyrrhizin was ingested in the morning and in the second experimental period, which followed after two weeks, glycyrrhizin was ingested in the evening. Each urine excretion was collected separately and the urine volume measured. Results showed that the maximum amount of metabolite is excreted between 19 and 20h after glycyrrhizin ingestion. Maximum elimination rates in six individuals were 27–110µg/h. After 4 days, 0.14–0.33% of ingested glycyrrhizin was detected in urine, which is in accordance with literature. There were no significant differences in elimination rates when glycyrrhizin was ingested in the morning or evening. It is often extremely difficult to establish licorice abuse as the cause of mineralocorticoid symptoms. We were able to detect glycyrrhizin metabolites even 4 days after ingestion of a single dose. This suggests a clinically applicable diagnostic HPLC method and provides some important clinical data on glycyrrhizin metabolism.