In vitro antimicrobial activity of propolis and Arnica montana against oral pathogens

Arnica and propolis have been used for thousands of years in folk medicine for several purposes. They possess several biological activities such as an ti-inflammatory, antifungal, antiviral and tissue regenerative, among other s. Although the antibacterial activity of propolis has already been demonst rated, very few studies have been done on bacteria of clinical relevance in dentistry. Also, the antimicrobial activity of Arnica has not been extensi vely investigated. Therefore the aim hen was to evaluate in vitro the antim icrobial activity, inhibition of adherence of mutans streptococci and inhib ition of formation of water-insoluble glucan by Arnica and propolis extract s. Arnica montana (10%, w/v) and propolis (10%, w/v) extracts from Minas Ge rais State were compared with controls. Fifteen microorganisms were used as follows: Candida albicans - NTCC 3736, F72; Staphylococcus aureus - ATCC 2 5923; Enterococcus faecalis - ATCC 29212; Streptococcus sobrinus 6715; Stre p. sanguis - ATCC 10556; Strep. cricetus - HS-6; Strep. mutans - Ingbritt 1 600; Strep. mutans - OMZ 175; Actinomyces naeslundii - ATCC 12104, W 1053; Act. viscosus OMZ 105; Porphyromonas gingivalis; Porph. endodontalis and Pr evotella denticola (the last three were clinical isolates). Antimicrobial a ctivity was determined by the agar diffusion method and the zones of growth inhibition were measured. To assess cell adherence to a glass surface, the organisms were grown for 18 h at 37 degrees C in test-tubes at a 300 angle . To assay water-insoluble glucan formation, a mixture of crude glucosyltra nsferase and 0.125 M sucrose was incubated for 18 h at 37 degrees C in test -tubes at a 30 degrees angle. Arnica and propolis extracts (20 mu l) were a dded to these tubes to evaluate the % of inhibition of cell adherence and w ater-insoluble glucan formation. The propolis extract significantly inhibit ed all the microorganisms tested (p < 0.05), showing the largest inhibitory zone for Actinomyces spp. The Arnica extract did not demonstrate significa nt antimicrobial activity. Cell adherence and water-insoluble glucan format ion were almost completely inhibited by the propolis extract at a final con centration of 400 mu g/ml and 500 mu g/ml, respectively. The Arnica extract showed slight inhibition of the adherence of the growing cells (19% for St rep. mutans and 15% for Strep. sobrinus) and of water-insoluble glucan form ation (29%) at these same concentrations. Thus, the propolis extract showed in vitro antibacterial activity, inhibition of cell adherence and inhibiti on of water-insoluble glucan formation, while the Arnica extract was only s lightly active in those three conditions. (C) 2000 Elsevier Science Ltd. Al l rights reserved.