The main objectives of this study were to evaluate the chemical constitution and allergenic potential of red propolis extract (RPE). They were evaluated, using high performance liquid chromatography (HPLC) and the release of β-hexosaminidase, respectively. A plethora of biologically active polyphenols and the absence of allergic responses were evinced. RPE inhibited the release of β-hexosaminidase, suggesting that the extract does not stimulate allergic responses. Additionally, the physicochemical properties and antibacterial activity of hydrogel membranes loaded with RPE were analyzed. Bio-polymeric hydrogel membranes (M) were obtained using 5% carboxymethylcellulose (M1 and M2), 1.0% of citric acid (M3) and 10% RPE (for all). Their characterization was performed using thermal analysis, Fourier transform infrared (FTIR), total phenolic content, phenol release test and, antioxidant activity through 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and Ferric Reducing Antioxidant Power (FRAP). The latter appointed to the similar antioxidant capacity of the M1, M2 and M3. The degradation profiles showed higher thermostability to M3, followed by M2 and M1. The incorporation of RPE into the matrices and the crosslinking of M3 were evinced by FTIR. There were differences in the release of phenolic compounds, with a higher release related to M1 and lower in the strongly crosslinked M3. The degradation profiles showed higher thermostability to M3, followed by M2 and M1. The antibacterial activity of the membranes was determined using the disc diffusion assay, in comparison with controls, obtained in the same way, without RPE. The membranes elicited antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis, with superior performance over M3. The hydrogel membranes loaded with RPE promote a physical barrier against bacterial skin infections and may be applied in the wound healing process.

Alginate encapsulates loaded with clove essential oil (CEO) were prepared by ionic gelation, with subsequent freeze-drying. The objective of the present work was to develop a product with the ability to protect CEO against its easy volatility and oxidation. The following techniques were used to characterize the formulations: eugenol release, degree of swelling, GC/MS, TGA/DSC, and SEM. The alginate solution (1.0%) containing different concentrations of CEO (LF1: 1.0%; LF2: 0.5%; LF3: 0.1%) was dropped into a 3.0% CaCl₂ solution. After lyophilization, the encapsulated samples were wrinkled and rigid, with high encapsulation power (LF3: 76.9% ± 0.5). Three chemical components were identified: eugenol (the major one), caryophyllene, and humulene. The antioxidant power (LF1: DPPH IC₅₀ 18.1 µg mL⁻¹) was consistent with the phenol content (LF1: 172.2 mg GAE g⁻¹). The encapsulated ones were thermally stable, as shown by analysis of FTIR peaks, eugenol molecular structure was kept unaltered. The degree of swelling was 19.2% (PBS). The release of eugenol (92.5%) in the PBS solution was faster than in the acidic medium. It was concluded that the low-cost technology used allows the maintenance of the content and characteristics of CEO in the three concentrations tested, offering a basis for further research with essential oil encapsulates.

The objective of this work was to develop a product capable of protecting Syzygium aromaticum (clove) essential oil against high volatility. Clove oil (CEO) was encapsulated in alginate by ionic gelation with subsequent freeze-drying. Characterization was carried out by GC/MS, TGA/DSC and antioxidant (DPPH), and total phenol (Folin-Ciocalteau) analysis. Eugenol was the majority (81.5%) and the encapsulation efficiency varied between 14.0%+0.96 (F1: 1.0% alginate) and 9.8%+0.35 (F2: 2.0% alginate) in wet encapsulates, and 23.5%+0.14 (LF1: 1.0% alginate) and 16.9%+0.16 (LF2: 2.0% alginate) in freeze-dried encapsulates. The total phenol content reached 714.8+0.97 EAG g-1 in LF1, with strong inhibition of the DPPH radical (71.4%). Freeze-drying provided a higher percentage of active ingredients per gram of encapsulated and it was possible to identify high thermal stability in LF1 (mass loss: 81.8%; 258.9 °C) compared to wet encapsulates (mass loss: 86.5%; 65.8°C). The use of the lowest concentration of alginate seems to have been favorable. In this way, the accessible technology used allows preserving the content and properties of the CEO, offering a basis for new encapsulated research.