## 3 Results and Discussion  
### Propolis Extracts Characterization  
The biological activity/properties of propolis are related to its chemical composition, namely the presence and concentration of specific phenolic compounds with antimicrobial and antioxidant properties [22; 29]. The concentration of those compounds in propolisis extracts could vary because of many factors, such as the production region, period of harvesting, methodological differences in extract preparations, solvent used, time and temperature of extraction [13; 29; 30; 31; 32]. For instance, [PERSON] et al. [29] showed that the antimicrobial action of aqueous propolisis extracts against different microorganisms was inferior compared to corresponding ethanolic propolis extracts. According to the same authors, this difference is a consequence of the low water solubility of most compounds with antimicrobial activity. In a preliminary approach, the total phenolic content and the antioxidant activity of 34 propolis extracts, obtained according to different methodologies and using samples of propolisis from different Portuguese regions, were determined (data not shown). Among these 34 extracts, four (E1, E2, E3 and E4) were selected for this work, because of their high phenolic content and antioxidant activity (DPPH and FRAP) (Table 1). The four ethanolic extracts of Portuguese propolisis showed a high total phenolic content (between 275-314 mg GAE/g dry extract) and a significant anti-radical activity according to the DPPH test (258-318 mg TE/g dry extract), and ferric reduction antioxidant power (3.7-4.6 mmol Fe\({}^{2+}\)/g dry extract). It is difficult to compare the obtained results, concerning total phenolic content and the antioxidant activities, with those obtained by others because of discrepancies in the methods used for quantification, compounds used as references, and the units used to express the results (g raw propolisis, mL of extract, g dry extract, etc,.). Nevertheless, the total phenolic contents observed were in line with other studies with propolisis samples from central coast and north-eastern regions of Portugal [10; 30]. Significant differences were observed among the total phenolic content and antioxidant activity of the four extracts analyzed. Thus, E1 showed a total phenolic content and a reducing activity significantly lower than E2, E3, and E4. On the other hand, E1 presented a DPPH radical-scavenging capacity significantly higher than E3 and E4. The differences observed among the four propolisis extracts can result from their specific composition in phenolic compounds. When analyzing different samples of propolisis, [PERSON] et al. [33] showed that the total phenolic content is not directly correlated with the biological activity of the extracts. Other authors have reported that the antioxidant and/or antimicrobial properties of propolisis extracts correlates not only with their concentration of total polyphenols, but also with the presence of some individual components, such as pinocembrin [34]. The analysis of 40 propolisis samples, collected from six different geographical origins in Portugal, showed that most of them had a similar phenolic profile, but with differences in concentrations, presenting the samples from north and central coast the highest phenolic concentration [35]. In general flavonoids are more abundant