Antibacterial Activity of Licochalcone A against Spore-Forming Bacteria

Abstract

Licochalcone A was isolated from the roots of licorice, Glycyrrhiza inflata, which has various uses in the food and pharmaceutical industries; isolation was followed by extraction with ethanol and column chromatography with silica gel. In this study, the activities of licochalcone A against some food contaminant microorganisms were evaluated in vitro. The vegetative cell growth of Bacillus subtilis was inhibited in a licochalcone A concentration-dependent manner and was completely prevented by 3 g of licochalcone A/ml. Licochalcone A showed a high level of resistance to heating at 80 to 121°C for 15 min. Licochalcone A did not inhibit the germination of heat-treated spores of B. subtilis induced by L-alanine. Licochalcone A showed effects against all gram-positive bacteria tested and especially was effective against all Bacillus spp. tested, with MICs of 2 to 3 g/ml, but was not effective against gram-negative bacteria or eukaryotes at 50 g/ml. Although the cationic antimicrobial peptides protamine and -poly-L-lysine resulted in the loss of antimicrobial activity in the presence of either 3% (wt/vol) NaCl or protease at 20 g/ml, the antibacterial activity of licochalcone A was resistant to these conditions. Thus, licochalcone A could be a useful compound for the development of antibacterial agents for the preservation of foods containing high concentrations of salts and proteases, in which cationic peptides might be less effective.

Isolation and antimicrobial activities of actinobacteria closely associated with liquorice plants Glycyrrhiza glabra L. and Glycyrrhiza inflate BAT. in Xinjiang, China

“…One possible explanation is that among the actinobacteria, antimicrobial activity against the tested indicator organisms is widespread, thereby making the tested set of indicators not suitable for differentiating the antimicrobial ranges. Another possible explanation is that the resistance against plant antimicrobials and the selfresistance against antimicrobials produced by the strains themselves are not connected (Tsukiyama et al, 2002).…”

Eugenol Reduces the Expression of Virulence-Related Exoproteins in Staphylococcus aureus

“…Currently, there is a trend in food processing to avoid the application of chemical preservatives such as NaCl and nitrates. Thus, the use of bioactive compounds derived from EOs as alternative antimicrobial agents is garnering great interest (14,37). Eugenol, the major phenolic compound and antimicrobial component of clove oil, has been registered by the European Commission for use as a flavoring ingredient in foodstuffs and is considered to pose no risk to consumer health (7).…”

Antibacterial Compounds from Glycyrrhiza uralensis

“…Some of these flavonoids have shown inhibitory activities against bacterial growth. [10][11][12] Streptococcus mutans (S. mutans) is an oral pathogen responsible for the initiation and progression of dental caries. 14 There is an urgent need for new antimicrobial compounds that can inhibit S. mutans effectively.…”