Defining in vitro topical antimicrobial and antibiofilm activity of epoxy-tigliane structures against oral pathogens

BACKGROUND: Peri-implantitis has become an inexorable clinical challenge in implantology. Topical immunomodulatory epoxy-tiglianes (EBCs), derived from the Queensland blushwood tree, which induce remodeling and resolve dermal infection via induction of the inflammasome and biofilm disruption, may offer a novel therapeutic approach. DESIGN: In vitro antimicrobial activity of EBC structures (EBC-46, EBC-1013 and EBC-147) against Streptococcus mutans, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in minimum inhibitory concentration, growth curve and permeabilization assays were determined. Antibiofilm activity was assessed using minimum biofilm eradication concentration (MBEC) experiments. Biofilm formation and disruption assays were analyzed using confocal laser scanning microscopy, scanning electron microscopy and direct plate counting. RESULTS: The observed antimicrobial efficacy of the tested compounds (EBC-1013 > EBC-46 > EBC-147) was directly related to significant membrane permeabilization and growth inhibition (p < 0.05) against planktonic S. mutans and P. gingivalis. Antibiofilm activity was evident in MBEC assays, with S. mutans biofilm formation assays revealing significantly lower biomass volume and increased DEAD:LIVE cell ratio observed for EBC-1013 (p < 0.05). Furthermore, biofilm disruption assays on titanium discs induced significant biofilm disruption in S. mutans and P. gingivalis (p < 0.05). CONCLUSIONS: EBC-1013 is a safe, semi-synthetic, compound, demonstrating clear antimicrobial biofilm disruption potential in peri-implantitis.