In vitro antimicrobial activities of anethole, carvacrol, cinnamon bark oil, eugenol, guaiazulene and thymol against G streptococci

The present study describes the antimicrobial activity of various natural \nsubstances against group G streptococci. A total of 50 strains of group G \nstreptococci was included in this study. The minimum bactericidal concentrations \nof 6 substances — anethole, eugenol, guaiazulene, carvacrol, cinnamon bark oil \nfrom Cinnamomum zeylanicum and thymol were obtained by the broth \nmicrodilution method. The substances were extended either directly in brain heart \ninfusion broth or in 24 % ethanol. Carvacrol was found to be the most effective \nsubstance with the highest antimicrobial activity, which inhibited the growth of 90 \n% of group G streptococci strains at the concentration of 236.7 :g ml–1. The \nminimum bactericidal concentrations of eugenol, oil from the bark of \nCinnamomum zeylanicum, and thymol were 1000 :g ml–1. Anethole and \nguaiazulene were the least effective natural substances in our study.