# Propolis as Natural Product in the Oral Cavity Bacterial Infections Treatment: A Systematic Review
## 4 Results
### Antibacterial Activity of Propolis in Oral Cavity Bacterial Infections
#### 4.2.1 In Vitro Studies  
[PERSON] et al. [6] examined how ethanolic extracts of propolis (EEP) from Brazil affected various strains of _Streptococcus spp_. The researchers used propolisis from the following regions of the country: Northeastern Brazil (BA), Southeastern (MG), and Southern (RS) Brazil. It was observed that all EEPs had biological activity against _S. mutans_. On the other hand, the highest potency of EEP BA was recorded for all criteria of _in vitro_ procedures that were assessed in this study. The latter suggested that EEP BA could constitute an effective anti-plaque/anti-caries agent. The antibacterial activity assays were carried out, and minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of EEPs against _S. mutans_, _S. sobrinus_, and _S. cricetus_ were determined. The values of MBC were four to eight times higher than the MIC values (Table 3). The authors observed also a marked inhibition of the adherence of _S. mutans_ and _S. sobrinus_ cells caused by EEPs, and the inhibition was significant at all concentrations when compared to the control (80% ethanol). Whereas, EEP BA in the concentration of 12.5 mg/mL inhibited cell adherence by 80% [6]. In the same year, [PERSON] et al. [21] analyzed the impact of southeastern Brazilian propolisis ethanolic extract (10%) against _S. sobrinus_, _S. sanguis_, _S. cricetus_, _S. mutans_, _A. naslundii_, _A. viscosus_, _P. gingivalis_, _P. endodontalis_, and _P. denticola_. The researchers concluded that propolisis could prevent dental caries and periodontal diseases. A significant increase in inhibition growth area after propolisis extract treatment was observed for all bacterial strains. Moreover, in case of the control (80% ethanol), the zone of microbial growth was not observed. The biggest inhibition zone (about 9 mm) was observed for both _Actinomyces spp_. strains [21]. In 2003, [PERSON] et al. [59] analyzed how the crude ethanolic extract of propolisis affected _S. mutans_ and _S. sobrinus_. The researchers observed that propolisis type 6 significantly inhibited the growth and adherence of _Streptococcus mutans_. It should be mentioned that there is a relationship between these biological activities and nonpolar components of propolisis. The authors determined MIC, MBC, and how bacteria adhered to a glass surface. It is noteworthy that the antibacterial activity of the EEP, hexane, and chloroform fractions was recorded. The MICs and MBCs of the test compounds are presented in Table 3[59]. [PERSON] et al. [60] extracted Brazilian propolisis from the Sao Paulo state using several solvents; therefore, they obtained extracts characterized by varied composition. The authors evaluated the activity of propolisis against _S. pyogenes_, _S. mutans_, _S. salivarius_, and _S. sobrinus_ with the use of _in vitro_ assays. Moreover, serial dilution in tubes proved to be the most appropriate method to estimate the bactericidal activity of the propolisis sample. It was observed that the synergistic effect of several components resulted in the bactericidal activity of propolisis. These components were determined with the use of HPLC, and the most efficient extraction was recorded when 50% ethanol was the solvent. Serial dilution in tubes and agar plate diffusion were employed to assay the bacterial activity of the above-mentioned extracts. Table 3 presents the range of MBCs of those six propolisis extracts which were serially diluted in a tube [60]. [PERSON] et al. [61] determined the antimicrobial effect of four various Anatolian propolisis samples on different groups of microorganisms, e.g., _S. mutans_ and _S. sobrinus_, and the researchers compared their chemical compositions. The authors determined MIC values and the chemical compositions of EEPs. The MIC values of the most effective propolisis are shown in Table 3. The GC-MS analysis indicated that the chief compounds of four Anatolian propolisis samples are flavonoids such as pinocombrin, pinostrobin, isalpinin, pinobanksin, quercetin, naringenin, galangin, and chrysin [61].