title: The anti-inflammatory activity of licorice, a widely used Chinese herb.
abstract: BACKGROUND
  Increasing incidence and impact of inflammatory diseases have encouraged the search of new pharmacological strategies to face them. Licorice has been used to treat inflammatory diseases since ancient times in China.
  
  
  OBJECTIVE
  To summarize the current knowledge on anti-inflammatory properties and mechanisms of compounds isolated from licorice, to introduce the traditional use, modern clinical trials and officially approved drugs, to evaluate the safety and to obtain new insights for further research of licorice.
  
  
  METHODS
  PubMed, Web of Science, Science Direct and ResearchGate were information sources for the search terms 'licorice', 'licorice metabolites', 'anti-inflammatory', 'triterpenoids', 'flavonoids' and their combinations, mainly from year 2010 to 2016 without language restriction. Studies were selected from Science Citation Index journals, in vitro studies with Jadad score less than 2 points and in vivo and clinical studies with experimental flaws were excluded.
  
  
  RESULTS
  Two hundred and ninety-five papers were searched and 93 papers were reviewed. Licorice extract, 3 triterpenes and 13 flavonoids exhibit evident anti-inflammatory properties mainly by decreasing TNF, MMPs, PGE2 and free radicals, which also explained its traditional applications in stimulating digestive system functions, eliminating phlegm, relieving coughing, nourishing qi and alleviating pain in TCM. Five hundred and fifty-four drugs containing licorice have been approved by CFDA. The side effect may due to the cortical hormone like action.
  
  
  CONCLUSIONS
  Licorice and its natural compounds have demonstrated anti-inflammatory activities. More pharmacokinetic studies using different models with different dosages should be carried out, and the maximum tolerated dose is also critical for clinical use of licorice extract and purified compounds.
authors.affiliation: a School of Chinese Pharmacy, Beijing University of Chinese Medicine , Beijing , China.
authors.forename: Rui
authors.initials: R
authors.lastname: Yang
authors.affiliation: a School of Chinese Pharmacy, Beijing University of Chinese Medicine , Beijing , China.
authors.forename: Bo-Chuan
authors.initials: BC
authors.lastname: Yuan
authors.affiliation: a School of Chinese Pharmacy, Beijing University of Chinese Medicine , Beijing , China.
authors.forename: Yong-Sheng
authors.initials: YS
authors.lastname: Ma
authors.affiliation: a School of Chinese Pharmacy, Beijing University of Chinese Medicine , Beijing , China.
authors.forename: Shan
authors.initials: S
authors.lastname: Zhou
authors.affiliation: a School of Chinese Pharmacy, Beijing University of Chinese Medicine , Beijing , China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000009:adverse effects / Q000302:isolation & purification / Q000493:pharmacokinetics / Q000627:therapeutic use*; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000517:prevention & control*; D018836:Inflammation Mediators / Q000378:metabolism; D020714:Maximum Tolerated Dose; D008517:Phytotherapy; D010936:Plant Extracts / Q000009:adverse effects / Q000302:isolation & purification / Q000493:pharmacokinetics / Q000627:therapeutic use*; D010946:Plants, Medicinal; D018570:Risk Assessment
chemical_list: D000893:Anti-Inflammatory Agents; D018836:Inflammation Mediators; D010936:Plant Extracts
keywords: Glycyrrhiza glabra L.; Glycyrrhiza inflata Bat.; Glycyrrhiza uralensis Fisch.; flavonoid; glycyrrhetinic acid; glycyrrhizin