# Functional and Antimicrobial Properties of Propolis from Different Areas of Romania
## 4 Discussion
The extract from H exhibited a higher flavonoid and phenolic acid value when compared with S and C2. However, it exhibited one of the lowest scores for antimicrobial activity, which suggests that antimicrobial activity is more influenced by flavonoids than the total phenolic acid. Considering the phenolic composition, the variability of phenolic and flavonoid concentrations observed in this study substantiates the impact of geographical origin and the influence of the local flora. Extracts A, S, and H exhibited the highest concentrations of phenolic acids, whereas C1 and C2 exhibited a greater abundance of flavonoids. These findings are consistent with those reported by [PERSON] et al. [42], who documented phenolic concentrations in ethanolic propolis extracts at 270 \(\pm\) 9.2 mg GAE/g, and [PERSON] et al. [43], who observed flavonoid levels ranging from 6.83 to 55.44 mg/g, contingent on the source and extraction methodology. This reinforces the notion that phenolic and flavonoid compounds serve as crucial determining factors in propolis bioactivity. Caffeic acid was identified in all samples, with the highest concentration observed in extract A (77.95 \(\upmu\)g/g). This finding is in accordance with the observations reported by [PERSON] et al. [44], who also noted significant inter-sample variability in the content of phenolic acids. Extract S exhibited the highest concentrations of both protocatechuric acid (0.62 \(\upmu\)g/g) and vanillic acid (1.3 \(\upmu\)g/g). These findings are consistent with those of [PERSON] et al. [45], who reported phenolic contents of 10-28.65 mg/mL in Malaysian stingless bee propolis. The present study thus provides further evidence linking phenolics to antimicrobial and antioxidant activities. Flavonoid analysis revealed that C1 is especially abundant in naringenin (55.41 \(\upmu\)g/g), apigenin (22.46 \(\upmu\)g/g), and pinocembrin (357.86 \(\upmu\)g/g), which correlates with its pronounced antimicrobial activity. This is consistent with the findings of [PERSON] et al. [46], who highlighted the pivotal role of flavonoids in propolis bioactivity, and [PERSON] et al. [47], who reported pinocembrin's therapeutic potential in antimicrobial applications. Extract S, which exhibits elevated levels of protocatechuric and vanillic acid, corroborates the findings of [PERSON] et al. [48], who reported a considerable polyphenol content in Brazilian green propolis. Similarly, the abundance of naringenin and apigenin in C1 is in accordance with the findings of [PERSON] [8], emphasising the antioxidant roles of flavonoids. The presence of CAPE in extracts A, C1, and S underscores the significance of botanical diversity, as CAPE exhibits a broad-spectrum of antimicrobial and antioxidant activity [49]. The concentrationsof polyphenols and flavonoids reported in this study are consistent with those reported in the literature, which highlights substantial variability across propolis samples. For example, [PERSON] et al. [50] reported total phenolic contents ranging from 2.93 to 8.00 mg/mL in Uruguayan propolis, which is similar to the phenolic profiles observed in samples A and S. Furthermore, the findings are consistent with those of [PERSON] et al. [51], who noted significant bioactivity at phenolic concentrations as low as 1 mg/mL. Furthermore, the observed variability in flavonoid content among the extracts is comparable to the findings of [PERSON] et al. [43], who reported a flavonoid range from 6.83 to 55.44 mg/g, depending on the extraction method and geographical origin. The FRAP assay results ranged from 4.8 to 7.4 mg Trolox Eq./g, with extract A demonstrating the highest ferric-reducing power. These findings align with those of [PERSON] et al. [52], who observed a FRAP value of 150 \(\upmu\)mol FeSO\({}_{4}\)/g for Romanian propolis, emphasising the significance of caffeic acid in antioxidant activity. Similarly, [PERSON] and [PERSON] [53] observed higher FRAP values for Brazilian green propolis, further underscoring the role of phenolic compounds in enhancing ferric-reducing capacity.