Biofilm Eradication Activity of Herb and Spice Extracts Alone and in Combination Against Oral and Food-Borne Pathogenic Bacteria

The purpose of this study was to select herbs and spices with potent biofilm eradication activities. Further, the combined effects of herb and spice extracts against pathogenic biofilms were evaluated. The biofilm eradication activities of ethanol extracts of 104 herbs and spices were measured by combining a colorimetric microbial viability assay with a biofilm formation technique. Ethanol extract of clove had potent biofilm eradication activities against Escherichia coli, Porphyromonas gingivalis, and Streptococcus mutans. Ethanol extracts of eucalyptus and rosemary had potent biofilm eradication activities against P. gingivalis, Staphylococcus aureus and S. mutans. The combination of extracts of clove with eucalyptus or rosemary showed synergistic or additive effects, or both, on biofilm eradication activities. The main biofilm inhibitors in the ethanol extracts of clove, eucalyptus and rosemary were eugenol, macrocarpals and carnosic acid, respectively. The combinations of extracts of clove with eucalyptus or rosemary had potent biofilm eradication activities against oral and food-borne pathogenic bacteria. The findings of the present study reveal that specific combinations of herb and spice extracts may prevent and control biofilm-related oral diseases, food spoilage, and food poisoning.