Compendium of the most significant studies with reference to properties, intake, effects.
Bhadoria N, Gunwal MK, Suryawanshi H, Sonarkar SS. Antiadherence and antimicrobial property of herbal extracts (Glycyrrhiza glabra and Terminalia chebula) on Streptococcus mutans: An in vitro experimental study. J Oral Maxillofac Pathol. 2019 Jan-Apr;23(1):73-77. doi: 10.4103/jomfp.JOMFP_103_18.
Abstract. Background: Herbal agents are used for treating different forms of diseases since decades. In the current study, the antiadhesive property of herbal extracts has been evaluated using Glycyrrhiza glabra (GG) and Terminalia chebula (TC) herbal extracts on Streptococcus mutans....Conclusion: Both the plant extracts exhibit inhibitory activity against S. mutans. However, TC had more clinically significant results than GG, but it was found statistically insignificant.
Wang L, Zhang K, Han S, Zhang L, Bai H, Bao F, Zeng Y, Wang J, Du H, Liu Y, Yang Z. Constituents Isolated from the Leaves of Glycyrrhizauralansis and Their Anti-Inflammatory Activities on LPS-Induced RAW264.7 Cells. Molecules. 2019 May 18;24(10):1923. doi: 10.3390/molecules24101923.
Abstract. Licorice, the root and rhizome of Glycyrrhiza uralansis Fisch, is one of the most frequently used Traditional Chinese Medicines in rigorous clinical trials to remove toxins and sputum, and to relieve coughing. However, the aerial parts are not used so widely at present. It has been reported that the aerial parts have many bioactivities such as anti-microbial and anti-HIV activities. In this study, we aimed to discover the bioactive compounds from the leaves of G. uralensis. Four new compounds, licostilbene A-B (1-2) and licofuranol A-B (3-4), together with eight known flavonoids (5-12), were isolated and identified from the leaves of G. uralensis. Their structures were elucidated mainly by the interpretation of high-resolution electrospray mass spectrometry (HR-ESI-MS) and nuclear magnetic resonance (NMR) spectroscopic data. Compared with quercetin, which showed a 50% inhibitory concentration (IC50) value of 4.08 μg/mL, compounds 1-9 showed significant anti-inflammatory activities by inhibiting lipopolysaccharide (LPS)-induced nitric oxide (NO) production with IC50 values of 2.60, 2.15, 3.21, 3.25, 2.00, 3.45, 2.53, 3.13 and 3.17 μg/mL, respectively. The discovery of these active compounds is important for the prevention and treatment of inflammation.
Zhou JX, Wink M. Evidence for Anti-Inflammatory Activity of Isoliquiritigenin, 18β Glycyrrhetinic Acid, Ursolic Acid, and the Traditional Chinese Medicine Plants Glycyrrhiza glabra and Eriobotrya japonica, at the Molecular Level. Medicines (Basel). 2019 May 10;6(2):55. doi: 10.3390/medicines6020055.
Abstract. Background: We investigated the effect of root extracts from the traditional Chinese medicine (TCM) plants Glycyrrhiza glabra L., Paeonia lactiflora Pall., and the leaf extract of Eriobotrya japonica (Thunb.) Lindl., and their six major secondary metabolites, glycyrrhizic acid, 18β glycyrrhetinic acid, liquiritigenin, isoliquiritigenin, paeoniflorin, and ursolic acid, on lipopolysaccharide (LPS)-induced NF-κB expression and NF-κB-regulated pro-inflammatory factors in murine macrophage RAW 264.7 cells. Methods: The cytotoxicity of the substances was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. RAW 264.7 cells were treated with LPS (1 μg/mL) or LPS plus single substances; the gene expression levels of NF-κB subunits (RelA, RelB, c-Rel, NF-κB1, and NF-κB2), and of ICAM-1, TNF-α, iNOS, and COX-2 were measured employing real-time PCR; nitric oxide (NO) production by the cells was quantified with the Griess assay; nuclear translocation of NF-κB was visualized by immunofluorescence microscopy with NF-κB (p65) staining. Results: All the substances showed moderate cytotoxicity against RAW 264.7 cells except paeoniflorin with an IC50 above 1000 μM. Glycyrrhiza glabra extract and Eriobotrya japonica extract, as well as 18β glycyrrhetinic acid and isoliquiritigenin at low concentrations, inhibited NO production in a dose-dependent manner. LPS upregulated gene expressions of NF-κB subunits and of ICAM-1, TNF-α, iNOS, and COX-2 within 8 h, which could be decreased by 18β glycyrrhetinic acid, isoliquiritigenin and ursolic acid similarly to the anti-inflammatory drug dexamethasone. NF-κB translocation from cytoplasm to nucleus was observed after LPS stimulation for 2 h and was attenuated by extracts of Glycyrrhiza glabra and Eriobotrya japonica, as well as by 18β glycyrrhetinic acid, isoliquiritigenin, and ursolic acid. Conclusions: 18β glycyrrhetinic acid, isoliquiritigenin, and ursolic acid inhibited the gene expressions of ICAM-1, TNF-α, COX-2, and iNOS, partly through inhibiting NF-κB expression and attenuating NF-κB nuclear translocation. These substances showed anti-inflammatory activity. Further studies are needed to elucidate the exact mechanisms and to assess their usefulness in therapy.
Zhou JX, Braun MS, Wetterauer P, Wetterauer B, Wink M. Antioxidant, Cytotoxic, and Antimicrobial Activities of Glycyrrhiza glabra L., Paeonia lactiflora Pall., and Eriobotrya japonica (Thunb.) Lindl. Extracts. Medicines (Basel). 2019 Mar 30;6(2):43. doi: 10.3390/medicines6020043.
Abstract. Background: The phytochemical composition, antioxidant, cytotoxic, and antimicrobial activities of a methanol extract from Glycyrrhiza glabra L. (Ge), a 50% ethanol (in water) extract from Paeonia lactiflora Pall. (Pe), and a 96% ethanol extract from Eriobotrya japonica (Thunb.) Lindl. (Ue) were investigated. Methods: The phytochemical profiles of the extracts were analyzed by LC-MS/MS. Antioxidant activity was evaluated by scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals and reducing ferric complexes, and the total phenolic content was tested with the Folin⁻Ciocalteu method. Cytotoxicity was determined with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in murine macrophage RAW 264.7 cells. Antimicrobial activity of the three plant extracts was investigated against six bacterial strains with the broth microdilution method. Results: Only Pe showed high antioxidant activities compared to the positive controls ascorbic acid and (-)-epigallocatechin gallate (EGCG) in DPPH assay; and generally the antioxidant activity order was ascorbic acid or EGCG > Pe > Ue > Ge. The three plant extracts did not show strong cytotoxicity against RAW 264.7 cells after 24 h treatment with IC50 values above 60.53 ± 4.03 μg/mL. Ue was not toxic against the six tested bacterial strains, with minimal inhibitory concentration (MIC) values above 5 mg/mL. Ge showed medium antibacterial activity against Acinetobacter bohemicus, Kocuria kristinae, Micrococcus luteus, Staphylococcus auricularis, and Bacillus megaterium with MICs between 0.31 and 1.25 mg/mL. Pe inhibited the growth of Acinetobacter bohemicus, Micrococcus luteus, and Bacillus megaterium at a MIC of 0.08 mg/mL. Conclusions: The three extracts were low-cytotoxic, but Pe exhibited effective DPPH radical scavenging ability and good antibacterial activity; Ue did not show antioxidant or antibacterial activity; Ge had no antioxidant potential, but medium antibacterial ability against five bacteria strains. Pe and Ge could be further studied for their potential to be developed as antioxidant or antibacterial candidates.
Martin BR, Reshamwala G, Short M. Treatment of a Woman With Glycyrrhiza glabra for Acute Sinusitis: A Case Report. J Chiropr Med. 2018 Dec;17(4):268-274. doi: 10.1016/j.jcm.2018.04.005.
Abstract. Objective: The purpose of this case report is to describe the treatment of a patient with acute sinusitis using Glycyrrhiza glabra. Clinical features: A 26-year-old woman presented with acute sinusitis of 10-day duration. Her symptoms included facial pressure and soreness around the frontal and maxillary sinuses, a headache, pharyngitis, a fever, rhinorrhea, nasal congestion with postnasal drip, a productive cough, myalgias, and fatigue. Intervention and outcome: After administration of 12 to 15 drops of a 2 000-mg tincture of G glabra twice a day, improvements were noted. Resolution of her symptoms occurred after 3 days of treatment. Conclusion: For the treatment of acute sinusitis, G glabra may be a natural therapeutic remedy.
Chittrarasu M, Sathyanarayana SS, Ahamed S, Aberna A, Bhavani S, Rajaraman G. Antimicrobial efficacy of liquorice against Enterococcus faecalis biofilms in various concentrations at time-dependent variables: An in vitro study. J Conserv Dent. 2019 Jan-Feb;22(1):7-11. doi: 10.4103/JCD.JCD_173_18.
Abstract. Introduction: The purpose this study was to evaluate the inhibitory efficacy of liquorice at various concentrations against Enterococcus faecalis and their biofilms at time-dependent variables in 24 h, 48 h, 72 h, 120 h, and 168 h. Materials and methods: The antienterococcal activity of liquorice and calcium hydroxide was detected employing concentration ranging from 1-4 g and interpreted based on the zone of inhibition. The ability of liquorice to inhibit E. faecalis biofilms during the stages of growth kinetics on microtiter plate was assessed, and the biofilm architecture was evaluated by scanning electron microscope (SEM). Results: Statistically significant antienterococcal was observed at 3 and 4 g of liquorice against 24 and 48 h on microtiter plates. This observation was also complimented by SEM studies of biofilm architecture cultivated in root canals. Conclusions: E. faecalis biofilms at 24 h and 48 h were highly susceptible to liquorice at concentration of 3 and 4 g.
Safety
Falet JP, Elkrief A, Green L. Hypertensive emergency induced by licorice tea. CMAJ. 2019 May 27;191(21):E581-E583. doi: 10.1503/cmaj.180550.
Hypertensive emergency induced by licorice tea.
Falet JP, Elkrief A, Green L.
CMAJ. 2019 May 27;191(21):E581-E583. doi: 10.1503/cmaj.180550.
Allergic Contact Dermatitis to Licorice Root Extract.
Kimyon RS, Liou YL, Schlarbaum JP, Warshaw EM.
Dermatitis. 2019 May/Jun;30(3):227-228. doi: 10.1097/DER.0000000000000475.
Licorice 
Glycyrrhizic acid
