title: 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 micrograms of licochalcone A/ml. Licochalcone A showed a high level of resistance to heating at 80 to 121 degrees 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 micrograms/ml, but was not effective against gram-negative bacteria or eukaryotes at 50 micrograms/ml. Although the cationic antimicrobial peptides protamine and epsilon-poly-L-lysine resulted in the loss of antimicrobial activity in the presence of either 3% (wt/vol) NaCl or protease at 20 micrograms/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.
authors.affiliation: Research Laboratory, Higashimaru Shoyu Co., Ltd., 100-3, Tominaga, Tatsuno, Hyogo 679-4193, Japan.
authors.forename: Ryo-Ichi
authors.initials: R
authors.lastname: Tsukiyama
authors.forename: Harumi
authors.initials: H
authors.lastname: Katsura
authors.forename: Nozomu
authors.initials: N
authors.lastname: Tokuriki
authors.forename: Makio
authors.initials: M
authors.lastname: Kobayashi
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development; D002599:Chalcone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D047188:Chalcones; D005506:Food Contamination / Q000517:prevention & control; D005519:Food Preservation / Q000379:methods*; D006035:Glycyrrhiza / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D018517:Plant Roots / Q000737:chemistry; D013171:Spores, Bacterial / Q000187:drug effects*
chemical_list: D047188:Chalcones; D002599:Chalcone; C070840:licochalcone A