Strong Antimicrobial Activity of Collinin and Isocollinin Against Periodontal and Superinfectant Pathogens In vitro

Periodontitis pathogenesis involves activation of host immune responses triggered by microbial dysbiosis. Therefore, controlling periodontal pathogens in-vivo is a main goal of periodontal therapy. New antimicrobials might help to control periodontal infection and improve treatment outcomes at "the dark times" of increasing antibiotic resistance. Here, we determined the biological activity of collinin and isocollinin against 8 bacterial strains. Antimicrobial activity of collinin and isocollinin, chlorhexidine digluconate (CHX) and sodium hypochlorite (NaClO) was evaluated against clinically relevant periodontal bacteria, like Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia, Dialister pneumosintes strains and superinfectants like Escherichia coli, Staphylococcusaureus, and Pseudomonasaeruginosa strains. A broth microdilution test was carried out to determine the minimum inhibitory concentration of collinin and isocollinin against those strains, and bacterial viability was determined by resazurin assay at diverse concentration and exposure times. P. gingivalis was the most susceptible strain to collinin and isocollinin (MIC 2.1 μg/mL and 4.2 μg/mL respectively). Other periodontal pathogens showed MICs <17 μg/mL for collinin and MICs between 20 and 42 μg/mL for isocollinin, whereas CHX and NaClO showed MICs of 62 and 326 μg/mL, respectively. Collinin and isocollinin also exhibited antimicrobial activity against superinfectant bacteria (MIC < 21 and < 42 μg/mL, respectively). Overall, collinin and isocollinin showed a remarkable antibacterial activity against relevant periodontal and superinfective bacteria, especially against P. gingivalis (MIC 2.1 μg/mL and 4.2 μg/mL respectively) and the highly virulent P. aeruginosa (MIC 5.2 and 20.8 μg/mL, respectively).