Extraction, assay, and analysis of antimicrobials from plants with activity against dental pathogens (Streptococcus sp.)

Abstract

Many dental and periodontal diseases are largely a question of bacterial etiology. Dental caries develop due to an increase of strongly acidogenic and aciduric gram-positive bacteria while common forms of periodontal disease are linked to anaerobic gram-negative bacteria in subgingival plaque. Many plants and plant-derived antimicrobial components are used in folklore therapeutics for the treatment of periodontal disorders and for the purposes of oral hygiene. Some have been evaluated for possible use in modern medicine, while thousands of other potentially useful/plants have not been tested. In this study, we evaluated the feasibility of screening for antibacterials isolated from plants with activity against three representatives of oral streptococci. We developed and tested the following methodologies: (1) Extraction of antibacterial components from plants; (2) Assays for antibacterial activity; (3) Chromatographic methods for initial analysis of compounds of interest. The screening process for plant antimicrobials consisted of extraction of plant material and assay of antibacterial activity using a spotting test with the selected oral streptococci as indicator strains. In addition, we developed chromatographic procedures that allow characterization and optimization of initial isolation steps. Depending on the indicator microorganisms used, the screening assay can target additional pathogens including other streptococci (group A and B, and pneumococci) and periodontal pathogens such as Porphyromonas. Also, we noted that the activity of some extracts varied against different oral bacteria. Our conclusion, supported by extensive data, was that the screening for antimicrobials from plants is a feasible approach to the identification of natural compounds with antimicrobial properties against dental pathogens.