Syfte: Syftet med denna in vitro studie var att testa 8 olika växtextrakt (kanel, nejlika, tranbär, aronia, humle, lime, grönt te, timjan) på två av Streptococcus mutans egenskaper, biofilmbildning och syraproduktion, samt mäta totala fenolmängden i varje växtextrakt. Material och metod: Vattenbaserat (humle, aronia, tranbär, grönt te) och etanolbaserat (nejlika, kanel, timjan, lime) växtextrakt testades på S. mutans biofilmbildning och syraproduktion. Biofilmen framställdes i mikrotiterplattor. Bacto™ Todd Hewitt Broth näringslösning och en nyligen isolerad stam av S. mutans användes. Den totala fenolmängden i varje växtextrakt mättes kolorimetriskt.Resultat: Kanel, nejlika och tranbär utövade inhibition på S. mutans biofilmbildning men humle, grönt te, timjan och lime inte påvisade någon inhibitionseffekt. Från studieresultatet framgår också att de testade växtextrakten förutom timjan hade inhibitionseffekt på S. mutans syraproduktion. Aronia som tidigare inte testats på kariogena bakterier uppvisade i likhet med tranbär inhibitionseffekt på S. mutans biofilmbildning och syraproduktion. Extraktens lägsta koncentration med inhibitionseffekt (MIC) på biofilmbildning och syraproduktion varierade mycket liksom växtextraktens totala fenolmängd och inget tydligt samband kunde påvisas mellan inhibitionseffekter och den totala fenolmängden.Slutsats: Vissa av de testade växtextrakten har inhibitionseffekt på S. mutans biofilmbildning och syraproduktion. Växtextraktens inhibitionseffekter på S. mutans biofilmbildning och syraproduktion är oberoende av varandra. Växtextraktens inhibitionseffekter på S. mutans biofilmbildning och syraproduktion är inte relaterade till den totalafenolmängden. / Aim: The aim of this in vitro study was to test eight different plant extracts (cinnamon, clove, cranberry, chokeberry, hops, lime, green tea, thyme) for inhibition of Streptococcus mutans properties biofilm formation and acid production, as well as measuring total phenolic content in each plant extract. Material and methods: Water-based (hops, chokeberry, cranberry, green tea) and ethanol-based (clove, cinnamon, thyme, lime) plant extract was tested on S. mutans biofilm formation and acid production. The biofilm was prepared in microtiter plates. Bacto Todd Hewitt Broth ™ broth and a freshly isolated strain of S. mutans were used. The total phenolic content in each plant extract was measured colorimetrically. Results: Cinnamon, clove and cranberry exerted inhibition on S. mutans biofilm formation, but hops, green tea, thyme and lime did not demonstrate inhibition effect. All tested plant extracts except for thyme had inhibitory effect on S. mutans acid production. Aronia, not previously tested on cariogenic bacteria showed, like the cranberry inhibition effect on S. mutans biofilm formation and acid production. Extracts lowest concentration with inhibition effect (MIC) on biofilm formation and acid production varied widely as well as plant extracts total phenol amount and no clear correlation between inhibition effects and total phenolic content was seen.Conclusion: Some of the tested plant extracts had inhibitory effect on S. mutans biofilm formation and acid production. Plant extracts inhibitory effects on S. mutans biofilm formation and acid production was independent of each other. Plant extracts inhibitory effects on S. mutans biofilm formation and acid production was not related to total phenol content.

Infections caused by antibiotic resistant pathogenic bacteria is an increasing issue inhealthcare, and development of new antimicrobial substances could contribute to combat the continued spread. Plants have historically been used in traditional medicine, have intrinsic defense mechanisms against microbes, and could therefore be a source for new antimicrobial agents. At the Department of Chemistry and Biomedicine at Linnaeus University, Kalmar, a total of 18 extracts made from 9 different combinations of Swedish-growing plants were available.The purpose of the current thesis was to investigate possible antimicrobial effects of the plant extracts in vitro, on a selection of Gram-positive (n=3) and Gram-negative (n=4) bacterial strains. Initial screening of all 18 extracts was performed with agar-based methods including agar well diffusion and direct application on inoculated agar. Detection of concentration-dependent antimicrobial effects was performed with four extracts on Staphylococcus aureus and Enterococcus faecalis. At inhibitory concentrations, viability was estimated as colony forming units/ml (CFU/ml).Screening showed that 11 of 18 extracts affected the growth of at least one of the strains tested. Gram-positive species were affected to a greater extent than Gram-negatives. Estimation of concentration dependency showed inhibitory effects at 50 mg/l in the most potent extracts. Viability estimation revealed an average reduction for both S. aureus and E. faecalis, as compared to the positive control. In conclusion, the study showed possible antimicrobial effects of several extract-bacteria combinations, disclosing potential substances for further investigations.