Reduction of Bacterial VSCs Production by Pine Bark Extract

Objectives: Halitosis affects a large proportion of the population. In most cases, it is caused by volatile sulfur compounds (VSCs) produced by bacterial species populating in the oral cavity. Especially, Gram-negative anaerobic bacteria are involved in VSCs generation. The objective of this study was to evaluate the effects of Pycnogenol^® (PYC), a phytochemical extract of French maritime pine tree, on the growth, volatile sulfur compound production and gene expression associated with halitosis.
Methods: Antibacterial activity against P. gingivalis, P. intermedia, P. nigrescens, F. nucleatum and A. actinomycetemcomitans, which have been associated with oral malodor, was determined by relative viability after the treatment with the extract. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the extract were determined according to the broth microdilution method. Gas chromatography analysis was performed to measure the concentration of VSCs from bacterial cultures, L-Cysteine and L-Methionine solution with or without PYC. Furthermore, the effect of PYC on the expression of mgl (the gene encoding L-methionine-α-deamino-γ-mercaptomethanelyase), which is responsible for CH₃SH production, in P. gingivalis was analyzed.

Results: Treatment with the extract for 15 min reduced the viable bacterial number in a dose-dependent manner. The MIC and MBC levels were 1000 μg/ml or more, so that PYC showed no apparent growth inhibition. Hydrogen sulfide was produced by all bacteria and PYC inhibited the production in a dose-dependent manner. Methyl mercaptan was markedly produced by P. gingivalis and F. nucleatum culture in 3 hours incubation. Treatment with PYC at 100 μg/ml significantly reduced CH₃SH level in P. gingivalis culture. Moreover, the expression of mgl gene in P. gingivalis was dose-dependently down-regulated by PYC treatment.

Conclusions: The results suggest that PYC is effective to control halitosis by decreasing bacterial VSCs production.