Atividade antimicrobiana de soluções de própolis

Abstract

The present study aimed to evaluate, in vitro, the antimicrobial activity of propolis extractive solutions on bacterial strains used as reference in antimicrobial susceptibility tests and on two periodontopathogens, through agar diffusion test and minimum inhibitory concentration. Three extractive propolis solutions were used: one marketed as 50% ethanolic propolis extract in 90°GL alcohol and the other two manipulated from in natura propolis to obtain 50% propolis solutions in 70°GL alcohol. The samples used in the study were submitted to thin layer chromatographic analysis, presenting the flavonoids pre-qualified by the standard: quercetin, chrysin, galangin, tectochrysin and pinocembrin. The bacterial strains used: Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Pseudomonas aeruginosa (ATCC 27853) were cultivated on Mϋeller-Hinton agar at 36°C for 48 hours. The strains of periodontopathogenic microorganisms: Porphyromonas gingivalis (ATCC 33277) and Actinobacillus actinomycetemcomitans (ATCC 29522) were cultured on blood agar supplemented with hemin and menadione, and incubated at 36°C for 5 days in anaerobic jars. The inoculum was prepared at concentration 1 on the McFarland scale. For the agar diffusion test, 7 mm diameter paper discs were impregnated with l0μ1 of the propolis extractive solutions. As a control, 10μ1 of the 70% and 90% ethyl alcohol solvent were used. For tests with facultative anaerobic microorganisms and P. aeruginosa, the inoculums were seeded in Petri dishes containing Müller-Hinton agar and incubated at 36°C for 48 hours. For P. gingivalis and A. actinomycetecomitans, the medium used was supplemented blood agar. After distributing the paper discs, the plates were incubated in an anaerobic atmosphere at 36°C for 5 days. For the evaluation of the minimum inhibitory concentration (MIC), the propolis solutions were diluted or not, in culture medium in the proportions 1:20, 1:40, 1.80, 1:160, 1:320, 1:640, 1: 1280 and 1:2560. The medium used to evaluate the MIC for facultative anaerobes and for P. aeruginosa was Müller-Hinton agar and for P. gingivalis and for A. actinomycetemcomitans, supplemented blood agar. The media surfaces were seeded with 4μ1 of inoculum and the plates were incubated at 37°C for a minimum of 48 hours. In the results obtained by the agar diffusion test, S. aureus, P.gingivalis and A. actinomycetemcomitans were inhibited by the three extractive solutions tested. In the evaluation of the minimum inhibitory concentration, E. faecalis and the species that showed sensitivity to the agar diffusion test were inhibited by different concentrations of the analyzed solutions. P. aeruginosa and E. coli were resistant to lower dilutions of propolis extractive solutions (1:20) in the culture medium. The highest inhibition patterns were evidenced in relation to P. gingivalis. In all tests, the microorganisms were resistant to the solvent: ethanol at 70°GL and 90°GL.