Pharmacological Effects and Underlying Mechanisms of Licorice-Derived Flavonoids

Table 5

The antibacterial, antiviral, and antiprotozoan effects of licorice flavonoids.

Effects	Compounds	Microorganism	Dose and effect	References
Antibacterial effects	1-Methoxyficifolinol, licorisoflavan A, and 6,8-diprenylgenistein	Streptococcus mutans	Showed bactericidal effects at the concentration of ≥4 μg/ml	[164]
	Flavonoid of G. uralensis extracts	Streptococcus mutans and Candida albicans	The inhibition zones of S. mutans and C. albicans increased in order: 50 μg/ml < 100 μg/ml < 150 μg/ml < 200 μg/ml	[165]
	Licoricidin and glabridin	Streptococcus mutans	Licoricidin had an MIC of 6.25 μg/mL and an MBC between 6.25 and 25 μg/mL; glabridin showed an MIC from 6.25 to 12.5 μg/mL and an MBC between 6.25 and 25 μg/mL against one reference (ATCC 25175) and four clinical (12A, 33A, INB, and T8) strains of S. mutans	[166]
	Flavonoid-rich extract of G. glabra	Helicobacter pylori	At minimum inhibitory concentration (MIC) of 100 μg/ml	[167]
	Flavonoids of G. glabra, namely, licoricone, glycyrin, and glyzarin	Acinetobacter baumannii	Significantly reduced quorum sensing regulated virulence factors of A. baumannii at 0.5 mg/ml	[168]
	Isoliquiritigenin and liquiritigenin	MRSA	MIC of both components exhibited significant anti-MRSA activity (50–100 μg/ml) against clinical isolates of MRSA	[169]
	Licochalcone A	Bacillus subtilis	The vegetative cell growth of B. subtilis was inhibited in a concentration-dependent manner and was completely prevented by 3 μg/ml	[170]
	Licochalcone A	Candida albicans	Reduced C. albicans biofilm growth at 625 μM in vitro; and mice treated with licochalcone A exhibited a markable reduction in total photon flux and CFU/ml/mg of tongue tissue sample	[171]
	Nisin/glabridin, nisin/licoricidin, and nisin/licochalcone A	Enterococcus faecalis	Efficiently restrained the growth of E. faecalis, with MICs ranging from 6.25 to 25 μg/mL	[172]
	6-Aldehydo-isoophiopogonone and liquiritigenin	Multidrug-resistant human bacterial Staphylococcus aureus	6-Aldehydo-isoophiopogonone and liquiritigenin showed activity against S. aureus with a zone inhibition of 10 ± 0.2 mm and 10 ± 0.3 mm	[173]
	Glabridin	Amphotericin B resistant Candida albicans	At an MIC of 31.25–250 μg/mL	[174]
	Liquiritin	Phytophthora capsici	Suppressed the P. capsici mycelial growth with EC50 of 658.4 mg/L and caused P. capsici sporangia to shrink and collapse	[175]
Antiviral effects	Echinantin and isoliquiritigenin	Influenza A viruses	Showed strong inhibitory effects on various neuraminidases from influenza viral strains, H1N1, H9N2, novel H1N1 (WT), and oseltamivir-resistant novel H1N1 (H274Y) expressed in 293T cells	[176]
	Licocoumarone, glyasperin C, 2′-methoxyisoliquiritigenin, glycyrin, licoflavonol, and glyasperin D	Rotaviruses, specially G5P [7] and G8P [7]	The 50% effective inhibitory concentrations (EC50) of the six compounds were 18.7–69.5 μM against G5P [7] and 14.7–88.1 μM against G8P [7]	[177]
	Quercetin of G. uralensis	Herpes simplex virus-1 (HSV-1)	Showed 50% decrease for 10 μg/ml quercetin and 90% decrease for 30 μg/ml of quercetin in plaque formation in Vero cells when incubated with infected cell lysates treated with quercetin; dose-dependently suppressed HSV-1 infection in Raw 264.7 cells	[178]
	Kanzonol Y	Dengue virus (DENV)	Exhibited anti-dengue-virus activity due to the outstanding docking properties with DENV protease, DENV RNA-dependent RNA polymerase, and DENV envelope protein	[179]
	Isobavachalcone	Porcine reproductive and respiratory syndrome virus (PRRSV)	Had potential anti-PRRSV activity and inhibited PRRSV replication at the postentry stage of PRRSV infection	[180]
Antiprotozoan effects	Licochalcone A	Chloroquine-susceptible (3D7) and chloroquine-resistant (Ddz) strains of Plasmodium falciparum	Had potent antiplasmodial efficacy against chloroquine-susceptible (3D7) and chloroquine-resistant (Ddz) strains of Plasmodium falciparum in vitro	[181]