MODE OF ANTIBACTERIAL ACTION OF RETROCHALCONES FROM GLYCYRRHIZA-INFLATA

Licochalcone A-D and echinatin, retrochalcones isolated from the roots of Glycyrrhiza inflata, showed antimicrobial activity. Among them, li cochalcone A and C had potent activity against some Gram-positive bact eria. These retrochalcones inhibited oxygen consumption in susceptible bacterial cells. The oxidation of NADH in bacterial membrane preparat ions was also inhibited by them. NADH-cytochrome c reductase was inhib ited by licochalcones, while cytochrome c oxidase was not. NADH-CoQ re ductase and NADH-FMN oxidoreductase were not inhibited. The site of re spiratory inhibition of licochalcones was thought to be between CoQ an d cytochrome c in the bacterial respiratory electron transport chain. (C) 1998 Elsevier Science Ltd. All rights reserved.