Effects of Pycnogenol on bone resorption by P. gingivalis infection

Pycnogenol (PYG) is a standardized bark extract of the French maritime pine tree (Pinus pinaster Aiton). The extract has been used in European countries as a dietary supplement because of its free-radical-scavenging activity. Furthermore, it has been reported to have antibacterial activity or inhibitory effects on various pathogenic activities of oral bacteria. Objectives: To examine the effect of the extract on alveolar bone loss induced by Porphyromonas gingivalis in rats. Methods: Antibacterial activity was determined by relative viability of the bacterium treated with the extract. Adherence of P. gingivalis to gingival epithelial cells was assessed by adding the PYG to the cells culture for 60 min prior to the infection. The inhibitory effect of the material on P. gingivalis adhesion was evaluated in compared to the control. Alveolar bone loss assay was performed as follows. Special pathogen-free (SPF) 3-week-old male Sprague-Dawley rats were infected with P. gingivalis suspended in 5% carboxymethylcellulose. Each rat received 0.5ml (1.5 x 10⁹ cells per ml) by oral gavage (five times) at 48-hour interval. PYG was mixed in feeds (0.025%, w/w) and animals were fed on the diet throughout the experiment. Results: The drastic antibacterial activity of the PYG was observed against P. gingivalis at the lowest concentration, 0.001% (P <0.05). Addition of the extract to epithelial cells inhibited the adhesion by P. gingivalis in a dose-dependent manner. The levels of bone loss in rats supplemented with PYG were significantly lower than those infected with P. gingivalis. Conclusion: These results suggest that French pine tree extract may prevent bone absorption in rats infected with P. gingivalis by inhibiting the adherence and accumulation of this organism.