Effect of eucalyptus-extract chewing gum on oral malodor: a double-masked, randomized trial.

BACKGROUND: Eucalyptus extracts were found to possess an antibacterial activity against some oral pathogens that produce oral malodor compounds in vitro; however, the clinical effects with respect to oral malodor in humans remain unproven. In the present investigation, a randomized clinical study was designed to test the hypothesis that eucalyptus-extract chewing gum can reduce oral malodor in the general adult population. METHODS: Subjects were randomly assigned to the following three groups: a high-concentration (0.6% eucalyptus extract) group (n = 32), a low-concentration (0.4% eucalyptus extract) group (n = 32), and a placebo group (n = 33). The intake period was 12 weeks. The organoleptic score, level of volatile sulfur compounds (VSCs), and tongue-coating score were recorded at baseline and 4, 8, 12, and 14 weeks. Treatment-to-time interactions among groups were evaluated by repeated-measures analysis of variance (ANOVA) followed by the Games-Howell pairwise comparison test. RESULTS: Relative to baseline readings, significant reductions in clinical parameters, including organoleptic and tongue-coating scores in the high- and/or low-concentration groups, occurred at 4, 8, 12, and 14 weeks (P <0.05). In addition, group-time interactions revealed significant reductions in the organoleptic score, VSCs, and tongue-coating score in both concentration groups compared to the placebo group (P <0.05). CONCLUSIONS: Eucalyptus-extract chewing gum had long-term effects on the olganoleptic score, levels of VSCs, and tongue-coating score. These findings suggest that eucalyptus-extract chewing gum may reduce oral malodor by decreasing the accumulation of tongue coating.

Fusobacterium nucleatum envelope protein FomA is immunogenic and binds to the salivary statherin-derived peptide.

We have previously shown that one of the minimal active regions of statherin, a human salivary protein, for binding to Fusobacterium nucleatum is a YQPVPE amino acid sequence. In this study, we identified the FomA protein of F. nucleatum, which is responsible for binding to the statherin-derived YQPVPE peptide. Overlay analysis showed that a 40-kDa protein of the F. nucleatum cell envelope (40-kDa CE) specifically bound to the YQPVPE peptide. The equilibrium association constant between the affinity-purified 40-kDa CE and the YQPVPE peptide was 4.30 x 10(6). Further, the purity and amino acid sequence analyses of the purified 40-kDa CE revealed approximately 98.7% (wt/wt) purity and a high degree of homology with FomA, a major porin protein of F. nucleatum. Thus, a FomA-deficient mutant failed to bind to the YQPVPE peptide. In addition, increased levels of a FomA-specific mucosal IgA antibody (Ab) and plasma IgG and IgA Abs were seen only in mice immunized nasally with cholera toxin (CT) and the purified 40-kDa FomA protein. Interestingly, saliva from mice that received FomA plus CT as a mucosal adjuvant nasally prevented in vitro binding of F. nucleatum to statherin-coated polyvinyl chloride plates. Taken together, these results suggest that induction of specific immunity to the 40-kDa FomA protein of F. nucleatum, which specifically binds to the statherin-derived peptide, may be an effective tool for preventing the formation of F. nucleatum biofilms in the oral cavity.

Identification of the binding domain of Streptococcus oralis glyceraldehyde-3-phosphate dehydrogenase for Porphyromonas gingivalis major fimbriae.

Porphyromonas gingivalis forms communities with antecedent oral biofilm constituent streptococci. P. gingivalis major fimbriae bind to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) present on the streptococcal surface, and this interaction plays an important role in P. gingivalis colonization. This study identified the binding domain of Streptococcus oralis GAPDH for P. gingivalis fimbriae. S. oralis recombinant GAPDH (rGAPDH) was digested with lysyl endopeptidase. Cleaved fragments of rGAPDH were applied to a reverse-phase high-pressure liquid chromatograph equipped with a C18 column. Each peak was collected; the binding activity toward P. gingivalis recombinant fimbrillin (rFimA) was analyzed with a biomolecular interaction analysis system. The fragment displaying the strongest binding activity was further digested with various proteinases, after which the binding activity of each fragment was measured. The amino acid sequence of each fragment was determined by direct sequencing, mass spectrometric analysis, and amino acid analysis. Amino acid residues 166 to 183 of S. oralis GAPDH exhibited the strongest binding activity toward rFimA; confocal laser scanning microscopy revealed that the synthetic peptide corresponding to amino acid residues 166 to 183 of S. oralis GAPDH (pep166-183, DNFGVVEGLMTTIHAYTG) inhibits S. oralis-P. gingivalis biofilm formation in a dose-dependent manner. Moreover, pep166-183 inhibited interbacterial biofilm formation by several oral streptococci and P. gingivalis strains with different types of FimA. These results indicate that the binding domain of S. oralis GAPDH for P. gingivalis fimbriae exists within the region encompassing amino acid residues 166 to 183 of GAPDH and that pep166-183 may be a potent inhibitor of P. gingivalis colonization in the oral cavity.