Magister Scientiae (Medical Bioscience) - MSc(MBS)Good oral health has a major influence on the general quality of life and well-being. Several chronic and systemic diseases have been attributed to poor oral health. With the increasing incidence of oral diseases, the global need for alterative prevention and treatment methods and safe, effective, and economical products has expanded. There are many studies showed that Streptococcus mutans has been implicated as major etiological agent of dental caries. South African has very rich natural flora especially Cape region. Several South African medicinal plants have been used since immemorial time for treatment of different human pathologies including dental problems. The antibacterial activities of plants extracts have been recognized and documented scientifically during the last few decades. In this project we aimed at the screening of 31 South African plants randomly collected from Cape region for their antibacterial activity against Streptococcus mutans initially at two concentrations (500 and 100 µg/ml).MIC’s and MBC’s were determined for the active plant extracts, as well as the qualitative studies of the effect of the active extracts on the biofilm formation. The best or the most active safe plant (Psoralea fruticans) was submitted to chromatographic separation to isolate the bioactive compounds which could be responsible for such activity. Identification of the pure active compounds was carried out using different spectroscopic techniques. Finally the biological evaluation of the isolated pure compounds was measured against S. mutans and also the cytotoxicity studies in-vitro against normal cells lines was carried out