Planta Med 2007; 73 - P_104
DOI: 10.1055/s-2007-986886

Antibacterial activity of liquorice, glycyrrhetinic acid and derivatives against Helicobacter pylori

R Krausse 1, J Bielenberg 2, W Blaschek 3
  • 1Institute for Infection Medicine, University Medical Center Schleswig-Holstein Campus Kiel (UKSH) and Christian-Albrechts University of Kiel, Brunswiker Straße 4, 24105 Kiel, Germany
  • 2Raphael-Pharmacy, Bahnhofstr. 53, 25364 Westerhorn, Germany
  • 3Institute of Pharmacy, Department of Pharmaceutical Biology, Christian-Albrechts University of Kiel, Gutenbergstrasse 76, 24118 Kiel, Germany

The medicinal use of Liquorice and its main constituent, glycyrrhizin (GL) on peptic ulcers has a long tradition [1]. The beneficial effects might also be, in part, due to their bactericidal effect on H. pylori (Hp) [2,3,4]. Therefore, the in vitro activity of liquorice (Extractum Liquiritiae [EL], GL content 6.4%), glycyrrhizic acid (GL), the aglycone of GL, glycyrrhetinic acid (GA) and a novel lipophilic derivative of glycyrrhetinic acid monoglucuronide (GAMG), acetylated GAMG (aGAMG) against several Hp strains has been investigated.

29 Hp strains (two clarithromycin [CLR]- and five metronidazol [MET]-resistant) were tested. The minimal inhibitory concentrations (MICs) were determined by the agar dilution method on BHI-agar, containing two fold serial dilutions (range [µg/ml]: EL 3.15–400, GA and GL 3.5–400, aGAMG 0.78–400). The killing kinetics of Hp strains were monitored in BHI-broth (˜ 106–7 cfu/ml), after 0, 4, 24, 48, 72 and 96h.

GA was the most potent compound (MIC50/90=50/100µg/ml). 23 of the tested 29 Hp strains were inhibited at MIC ≤50µg/ml. CLR-resistant strains were susceptible at 12.5 and 25µg/ml, 4 MET-resistant strains at 25–50 and one at 200µg/ml. The MIC (µg/ml) of aGAMG tested with 24 strains was ≤6.25 (7 strains), 50 (1 strain), 100–200 (3 strains) and ≥400 (13 strains). EL and GL were less active (MICs >400µg/ml). GA exhibited rapid, concentration and strain-dependent bactericidal activity.

The potent in vitro activity of GA against different susceptible and antibiotic-resistant strains of H. pylori provides an extended interpretation of its beneficial effect on peptic ulcers.

References: [1] Armanini, D. et al. (2000) Exp. Clin. Endocrinol. Diabetes 110: 257–261. [2] Kim, D.H. et al. (2000) Arch. Pharm. Res. 23: 172–177. [3] Dunn, B.E. et al. (1997) Clin. Microbiol. Rev. 10:720–741. [4] Krausse, R. et al. (2004)J. Antimicrob. Chemother. 54:243–246.