Antibacterial Activity of Phenolic Compounds in Olive Oil Extracts on Periodontopathogenic Oral Bacteria

Phenolic compounds are secondary metabolites of plants metabolism and can be found in olive oil. They exhibit antimicrobial activity towards both gram-positive and gram-negative bacteria. However, little is known about the antibacterial activity of the compounds towards periodontopathogens. The study aimed to investigate the potential of these compounds as antibacterial agents towards pathogens, specifically Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum. Phenolic compounds were extracted from extra virgin olive oil (EVOO) through liquid-liquid separation using methanol:water (70:30), and hexane. It was then prepared in various concentrations to determine its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against the periodontopathogens. The anti-adhesion activity was quantified using crystal violet staining while the effects on the morphology were examined through scanning electron microscopy (SEM). The MICs of the phenolic compounds on A. actinomycetemcomitans, P. gingivalis and F. nucleatum were 31.25 mg/mL, 62.5 mg/mL and 125 mg/mL, respectively. The MBCs of the phenolic compounds on A. actinomycetemcomitans and F. nucleatum were 62.5 mg/mL and 125 mg/mL, respectively suggesting this compound can eradicate these bacteria. There was no bactericidal effect on P. gingivalis. The adhesion of all the bacteria was interrupted by the compounds at the lowest concentration (1.95 mg/mL). SEM findings showed disruption of bacterial cell surfaces such as blebs and disintegration of cells after exposure to this extract. Phenolic compounds of olive oil exhibited antibacterial activity against the tested pathogens, with bactericidal effects on A. actinomycetemcomitans and F. nucleatum and bacteriostatic effects on P. gingivalis.