Investigation of antibacterial and biofilm inhibition activity of Michelia figo leaf extracts against dental bacterium

Dental plaque, a complex microbial biofilm, is a pathogenic factor in dental diseases such as dental caries and periodontal disease. The dental diseases usually begin with the formation of dental plaques. S. mutans, S. sobrinus and S. sanguinis are the primary bacterium for the biofilm formation. Some antibiotics and chemical agents could treat oral infections but often accompanied with side effects and drug resistance. To discover agents that can prevent biofilm formation or destroy biofilm is thus considered as a good strategy to avoid drug resistance. Plant natural products are our primary source for discovery of such potential agents. In our study, we have evaluated more than 1,000 plant extracts for their antibacterial and anti-biofilm activity. One plant, Michelia figo (Lour.) Spreng., was found to effectively prevent biofilm formation of dental bacteria. We thus re-collected the plant materials (leaves and stems) for further phytochemical investigation. Bioassay-guided separation was carried out to get the active constituents from this plant, which may lead to the potential use of the plant to prevent dental biofilm formation. [The work described in this paper was supported by HKBU Interdisciplinary Research Matching Scheme (RC-IRMS/12 – 13/03)].