Elucidation on Abnormal Behavior of Glycyrrhizin Salts in High Performance liquid Chromatography Determination for Quasi-Drug Products

Glycyrrhizinates such as monoammonium and dipotassium glycyrrhizinates which are extracted from licorice, converted to easily water-soluble salts and refined have been formulated in many quasi-drug products as an anti-inflammatory agent. A quantitative analysis of glycyrrhizinates in quasi-drug products has usually and successfully been carried out by high performance liquid chromatography (HPLC). However, a slightly higher value than the actual content has sometimes been observed in daily analysis. As the result of our various studies to investigate these phenomena, we finally found that a minor constituent in commercial glycyrrhizinates, which was identified as monomethyl glycyrrhizinate, was hydrolyzed after they were formulated in quasi-drug products and converted to glycyrrhizin which in turn was determined by HPLC as a higher value.