Liquorice for pain?

Rae F Bell,Jari Yli-Kauhaluoma,Eija A Kalso,Vânia M Moreira

doi:10.1177/20451253211024873

Abstract

Liquorice has a long history of use in traditional Chinese, Ayurvedic and herbal medicine. The liquorice plant contains numerous bioactive compounds, including triterpenes, flavonoids and secondary metabolites, with glycyrrhizin being the main active compound. Liquorice constituents have been found to have anti-inflammatory, antioxidant, antiviral, anticancer, hepatoprotective and neuroprotective properties. In addition, they appear to have antidepressant actions and effects on morphine tolerance. Glycyrrhizin, its metabolite glycyrrhetic (glycyrrhetinic) acid and other liquorice-derived compounds such as isoflavonoids and trans-chalcones, exert potent anti-inflammatory effects via a wide range of mechanisms including high mobility group box 1 protein (HMGB1) inhibition, gap junction blockade and α2A-adrenoceptor antagonism. These properties, together with an increasing body of preclinical studies and a long history of use in herbal medicine, suggest that liquorice constituents may be useful for pain management. Glycyrrhizin is used widely in the confectionary, food and tobacco industries, but has documented adverse effects that may limit clinical use. Whether liquorice plant-derived compounds represent a novel class of analgesics is yet to be established. Having a host of bioactive compounds with a broad range of mechanisms of effect, liquorice is a plant that, in the future, may give rise to new therapies for pain.

Highlights

Liquorice has a long history of use in traditional Chinese (TCM), Ayurvedic and herbal medicine as a treatment for kidney, lung and liver ailments, gastric discomfort, arthritis and infections.[1,2]
The 10th edition of the European Pharmacopoeia contains monographs on liquorice root (Liquiritiae radix) and liquorice extract for flavouring purposes (Liquiritiae extractum siccum ad saporandum), a herbal drug and herbal preparation, respectively.[4]
Liquorice constituents have been found to have anti-inflammatory, antioxidant, antiviral, anticancer, hepatoprotective and neuroprotective properties. They appear to have antidepressant actions and effects on morphine tolerance. Liquorice constituents such as glycyrrhizin (GLA) 1, its metabolite glycyrrhetic acid (GRA) 3 and other liquorice-derived compounds such as glabridin 5 and isoliquiritigenin 7 exert these effects via a range of mechanisms including high mobility group box 1 protein (HMGB1) inhibition, gap junction blockade and α2A-adrenoceptor antagonism

Summary

Introduction

Liquorice has a long history of use in traditional Chinese (TCM), Ayurvedic and herbal medicine as a treatment for kidney, lung and liver ailments, gastric discomfort, arthritis and infections.[1,2] Liquorice is used in TCM to alleviate pain.[3]. Activity.[25] In a rodent study, magnesium isoglycyrrhizinate (MgIG) reversed methotrexateinduced hepatotoxicity.[26] COX-2 expression was reduced significantly by 7 days administration of MgIG In another preclinical study, a single dose of ammonium glycyrrhizinate induced antiinflammatory and antinociceptive effects lasting 24–48 h, presumably due to its ability to bind the COX/microsomal prostaglandin E synthase (mPGE) pathway.[27] A murine study found that GLA 1 had significant anti-inflammatory and antinociceptive activities that were mediated via attenuating the expression of COX-2 and proinflammatory cytokines.[28] GLA 1 has been proposed recently as a treatment for rheumatoid arthritis and endometriosis by targeting COX-2.23,29. Peripheral nerve injury [tibial nerve injury (TNI)] resulted in the

Triterpenoid saponin

Semisynthetic triterpenoid

Findings

Conclusions