Identification of glycyrrhizin metabolites in humans and of a potential biomarker of liquorice-induced pseudoaldosteronism: a multi-centre cross-sectional study
Liquorice [main ingredient, glycyrrhizin (GL)] is widely used as a food sweetener and herbal medicine. Occasionally, liquorice consumption causes pseudoaldosteronism as a side effect which causes oedema, hypokalaemia, and hypertension due to hyperactivity of mineral corticoid receptor. We aimed to detect GL metabolites in human blood and urine samples and to determine the pathological relationship between GL metabolites and pseudoaldosteronism. For this multi-centre, retrospective, cross-sectional study, we recruited patients who had visited Center for Kampo Medicine in Keio University Hospital, Department of Japanese Oriental (Kampo) Medicine in Chiba University Hospital, Clinic of Japanese Oriental (Kampo) Medicine in Kanazawa University Hospital, and Department of Oriental Medicine in Kameda Medical Center from November 2011 to July 2018. We collected laboratory data including concentration of serum potassium, plasma activity of renin and aldosterone, and residual blood and/or urine samples of participants who had experienced symptoms/signs of pseudoaldosteronism in the form of increase in blood pressure and occurrence or aggregation of oedema while taking liquorice-containing herbal preparations, and measured GL metabolites using a highly selective liquid chromatography tandem mass spectrometer system. We registered 97 participants (mean age 60 ± 15 years; male:female 14:83). 18β-glycyrrhetinic acid (GA) was detected in 67 serum samples (median 122 nM, range 5 nM–1.8 µM) and 18β-glycyrrhetyl-3-O-sulfate (compound 3) in 68 samples (median 239 nM, range 2 nM–4.2 µM). 3-Monoglucuronyl 18β-glycyrrhetinic acid, 22α-hydroxy-18β-glycyrrhetyl-3-O-sulfate-30-glucuronide, 22α-hydroxy-18β-glycyrrhetyl-3-O-sulfate, and GL itself were not or rarely detected. We could not find any correlation between blood pressure or peripheral oedema and serum concentration of GL metabolites. Sulfotransferase 2A1 catalysed the metabolic reaction of GA to compound 3, a major GL metabolite in human blood. High serum concentration of compound 3 was related to lower renin, aldosterone, and potassium levels, suggesting a pathological relationship between compound 3 and liquorice-induced pseudoaldosteronism. This is the first study to identify the association between a novel metabolite, compound 3, and the incidence of pseudoaldosteronism, highlighting it as a promising biomarker.
KeywordsKampo medicine Side effect Liquorice Glycyrrhizin
A part of the current study was presented at the 70th Annual Conference of Japan Society of Oriental Medicine held in Tokyo, Japan in 2019. We would like to thank Kaori Sawai, Akiko Shirai, and Koh’ichi Ryu for helping with sample collection, Asuka Hirasawa and Miaki Mitamura for assisting in the analysis of GL metabolites, Yuna Tashita for validating SULT1A1 activity, and Editage (http://www.editage.com) for English language editing.
KT and TY had full access to the clinical data used in this study and take responsibility for the data’s integrity and the accuracy of the data analysis. YM, KI, and TM had full access to the basic research data used in this study and take responsibility for the analysis of GL metabolites. KT, TY, and TM wrote a draft of this manuscript. TY, TN, KOO, and KM participated in designing the study and collecting human samples and clinical data. TN, MM, and KW reviewed a draft of this manuscript, and KW made comments. All authors read and approved the final manuscript.
This work was supported by Grant-in-Aid of a Research Project for Improving Quality in Healthcare and Collecting Scientific Evidence on Integrative Medicine from the Japan Agency for Medical Research and Development in data analysis and presentation (AMED) under Grant numbers, JP17lk0310036h0001, JP18lk0310049h0001, and JP19lk0310064h0001. The funding source had no involvement in the interpretation of data, writing of the report, and the decision to submit the article for publication.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in the studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
All registered participants provided written informed consent, and the study design was approved by the appropriate institutional review boards at Keio University, Chiba University, Kanazawa University, and Kameda Medical Center.
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