Suhad M. Hamdon¹, Ghada Y. Abdul-Rahman^1,

Aims: The aim of the study was to evaluate the susceptibility of Aggreagatibacter actinomycetemcomitans to licorice root (Glycyrrhiza glabara) extracts and to compare the antibacterial effect of this extract on biofilm versus planktonic cell. Materials and Methods: Subgingival plaque samples were taken to obtain fresh clinical isolates of A. actinomycetemcomitans. The isolates were divided into: biofilm positive (biofilm cell) and biofilm negative (planktonic cell) using crystal violet assay. Well diffusion method has been used to assess and compare the antibacterial effect of the ethanolic and aqueous extract of Glycyrrhiza glabara (licorice root) on the biofilm and planktonic clinical isolates of A. actinomycetemcomitans. Licorice root extracts were prepared at different concentrations: (50 µg), (100 µg), (250 µg), tetracycline at concentration (25 µg) used as control positive, and DMSO (dimethyle sulphaxsazol) for alcoholic licorice extract and sterile water as control negative for aqueous licorice extract. Results: Antimicrobial sensitivity test proved that (licorice root extract has good antibacterial effect against A actinomycetemcomitans and this effect was less against biofilm cell when compared with planktonic cell, and the effective concentration of licorice extracts was 250 µg which produced inhibition zone compatible to tetracycline. Conclusions: This study proved that licorice extract had antibacterial effect against A. actinomycetyemcomitans, and this effect was decreased on biofilm phenotype which is more resistant to antimicrobial agents.

Aggregatibacter actinomycetemcomitans, Glycyrrhiza glabara, biofilm, planktonic