Anxiolytic- and antidepressant-like effects of the ethanolic extract from Citrus limon plant widely used in Northeastern Brazil

Propolis is an organotherapeutic product collected by honeybees and has relevant pharmacological properties, highlighting the high antimicrobial activity. This study aimed to evaluate in vitro the synergistic effect between three ethanol extract of different Brazilian propolis samples: green (Baccharis dracunculifolia) (A), red (Dalbergia ecastophyllum) (B) and brown (Copaifera sp) (C) propolis by antimicrobial sensitivity of Streptococcus mutans(ATCC 25175) and Streptococcus sanguinis (ATCC 10557), through the agar diffusion method. Aliquots of each microorganism containing 1.0x106 CFU / mL were inoculated on Mueller- Hinton agar supplemented with 5% dextrose and sterile blank discs containing 20 μL of each propolis sample (A, B, C) and combined (A + B, A + C, B + C, and  A + B + C) were planted on the agar. Tetracycline 30 mg discs and blank discs containing 70% alcohol served as controls. After incubation at 37°C in bacteriological incubator in a 5% CO2 atmosphere for 24 and 48 h the inhibition zones were measured. The results showed that all extracts inhibited the growth of both microorganisms, while the samples (B) and (A + B), were significantly more effective than the others. For samples B and C similar results were observed.   Key words: Streptococcus mutans, Streptococcus sanguinis, Brazilian propolis, antimicrobial activity, synergism.