ABSTRACT
Nineteen flavonoids isolated from licorice (Glycyrrhiza glabra, G. inflata and G. uralensis) were tested for their antimicrobial activities against methicillin sensitive Staphylococcus aureus, methicillin resistant S. aureus, Micrococcus luteus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa.
Subject(s)
Anti-Bacterial Agents/pharmacology , Flavonoids/pharmacology , Glycyrrhiza , Methicillin Resistance , Phytotherapy , Staphylococcus aureus/drug effects , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/therapeutic use , Bacillus subtilis/drug effects , Dose-Response Relationship, Drug , Escherichia coli/drug effects , Flavonoids/administration & dosage , Flavonoids/therapeutic use , Humans , Klebsiella pneumoniae/drug effects , Microbial Sensitivity Tests , Micrococcus luteus/drug effects , Plant Roots , Pseudomonas aeruginosa/drug effectsABSTRACT
Licorice is the most used crude drug in Kampo medicines (traditional Chinese medicines modified in Japan). The extract of the medicinal plant is also used as the basis of anti-ulcer medicines for treatment of peptic ulcer. Among the chemical constituents of the plant, glabridin and glabrene (components of Glycyrrhiza glabra), licochalcone A (G. inflata), licoricidin and licoisoflavone B (G. uralensis) exhibited inhibitory activity against the growth of Helicobacter pylori in vitro. These flavonoids also showed anti-H. pylori activity against a clarithromycin (CLAR) and amoxicillin (AMOX)-resistant strain. We also investigated the methanol extract of G. uralensis. From the extract, three new isoflavonoids (3-arylcoumarin, pterocarpan, and isoflavan) with a pyran ring, gancaonols A[bond]C, were isolated together with 15 known flavonoids. Among these compounds, vestitol, licoricone, 1-methoxyphaseollidin and gancaonol C exhibited anti-H. pylori activity against the CLAR and AMOX-resistant strain as well as four CLAR (AMOX)-sensitive strains. Glycyrin, formononetin, isolicoflavonol, glyasperin D, 6,8-diprenylorobol, gancaonin I, dihydrolicoisoflavone A, and gancaonol B possessed weaker anti-H. pylori activity. These compounds may be useful chemopreventive agents for peptic ulcer or gastric cancer in H. pylori-infected individuals.
