Effects of Streblus asper leaf extract on the biofilm formation of subgingival pathogens

Streblus asper leaf extract (SAE) possesses antibacterial activity towards Streptococcus mutans and periodontal pathogens, such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. However, there is no report on inhibitory effects of SAE against subgingival biofilm formation. The purpose of this study was to investigate the inhibitory effects of SAE on subgingival biofilm formation using an in vitro model. Subgingival plaque samples from 5 periodontitis patients were cultivated in saliva-coated 96-well microtiter plates in the presence of SAE at concentrations 0.5-90 mg/ml under anaerobic atmosphere at 37 °C for 2, 4 and 8 days by replacing every 2 days with fresh medium alone or SAE-containing medium. Biofilm formation was determined quantitatively by crystal violet staining. TaqMan-based real-time polymerase chain reaction was used to quantify the numbers of P. gingivalis, A. actinomycetemcomitans and total bacteria in the grown subgingival biofilm. The results showed that SAE exhibited more than 70% anti-biofilm activity at 90 mg/ml. The reduction in cell numbers of P. gingivalis, A. actinomycetemcomitans and total bacteria in subgingival biofilm of test groups were observed compared to untreated control. These results revealed that SAE is able to inhibit in vitro subgingival biofilm formation and reduce the numbers of P. gingivalis, A. actinomycetemcomitans and total bacteria.