Antimicrobial effects of o-cymen-5-ol and zinc, alone & in combination in simple solutions and toothpaste formulations.

This study aimed to evaluate antimicrobial effects of an o-cymen-5-ol/zinc system. o-Cymen-5-ol and zinc gluconate minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined against Streptococcus mutans, Actinomyces viscosus, Porphyromonas gingivalis, Fusobacterium nucleatum and Candida albicans. Synergy was investigated by checkerboard MIC/MBC; inhibition of P. gingivalis protease activity and S. mutans glycolysis were investigated. Slurried toothpastes containing the system were assessed in kill time assays against S. mutans and E. coli. o-Cymen-5-ol MIC was between 1.7 mM to 3.4 mM; MBC was 3.4 mM to 6.7 mM. Zinc gluconate MIC was 2.8 mM to 11 mM; MBC was between 11 mM and >44 mM. The two agents in solution showed synergy (FICI≤0.50) against P. gingivalis and F. nucleatum, with MIC of 0.42 mM/0.69 mM for o-cymen-5-ol/zinc gluconate, respectively. Zinc inhibited glycolysis and protease to a greater degree than o-cymen-5-ol; glycolysis inhibition by the two agents was additive. o-Cymen-5-ol/zinc chloride in toothpaste showed greater effects than placebo (120s log10 kill=7.35±0.40 and 4.02±0.40, respectively). The zinc/o-cymen-5-ol system has direct antimicrobial effects and inhibits oral disease-related processes. Synergistic effects were seen against anaerobes. A system combining o-cymen-5-ol and zinc shows properties desirable for incorporation in toothpastes.