The antimicrobial activity

In this study it was verified the antimicrobial activity of a sample of green propolis originated from
Bacharis dracucunlifolia (“alecrim”) against 16 pathogenic microorganisms of the oral cavity (table 1).
Microorganisms associated with oral mucosa diseases, dental caries, periapical abscess and periodontitis
were selected for this study. More than 200 different components have been identified in propolis
solutions and phenolic compounds seem to be associated with biological activities, including propolis
antimicrobial properties8,9,10,11. In this work it was verified the antimicrobial susceptibility of specific
components of ethanolic fractions of BGP. Kruskal-Wallis test indicated no significant differences in
the susceptibility profile of isolated compounds (tables 1 and 2) in comparison to total BGP (P< 0.05).
None of the assayed fractions was more active than BGP, suggesting that the antibacterial activity is
probably caused by the synergistic effects of different compounds, corroborating previously reported
results12,13 . In yeast, propolis biological mechanism of action appears to be associated with cell wall and
plasm membrane disruption observed through electron microscopy14. On the other hand, propolis
mechanism of action on bacteria is complex and a simple analogy to the mode of action of classic
antibiotics can not be made13,15,16. Although the antimicrobial properties of propolis have been subject of
many investigations, it is difficult to compare different studies, since composition of propolis may vary
geographically and several methods of study are used in different laboratories17. However, in this study
both Gram positive and Gram negative bacteria were sensitive to BGP and to isolated compounds
differently of other studies17,18,19. This finding shows that Brazilian green propolis has significant
antimicrobial potential against bacteria and yeast, but the effect will be specie dependent16.
As far as we are concern this is the first documented paper that reports the antimicrobial activity of
isolated compounds of Brazilian green propolis extract against pathogenic oral bacteria and yeast. The
MIC and the MBC results showed significant differences of BGP on the microorganisms of the same
group, e.g., MIC values for Candida spp. ranged from 20 to 50 mg/ml. Similarly, for microaerophilic
Gram positive bacteria, MIC values ranged from 25 to 50mg/ml could be detected. The same profile was
observed for MBC. The results of diffusion in agar have not shown significant statistical differences
between less pathogenic species (S.sanguis/ C. glabrata) and more aggressive microorganisms (A.
actinomycetemcomitans / C. albicans).