Insights from Syzygium aromaticum Essential Oil: Encapsulation, Characterization, and Antioxidant Activity.

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.

Coexistence of the Oxazolidinone Resistance-Associated Genes cfr and optrA in Enterococcus faecalis From a Healthy Piglet in Brazil.

Oxazolidinones are one of the most important antimicrobials potentially active against glycopeptide- and ß-lactam-resistant Gram-positive pathogens. Linezolid-the first oxazolidinone to be approved for clinical use in 2000 by the US Food and Drug Administration-and the newer molecule in the class, tedizolid, inhibit protein synthesis by suppressing the formation of the 70S ribosomal complex in bacteria. Over the past two decades, transferable oxazolidinone resistance genes, in particular cfr and optrA, have been identified in Firmicutes isolated from healthcare-related infections, livestock, and the environment. Our goals in this study were to investigate the genetic contexts and the transferability of the cfr and optrA genes and examine genomic features, such as antimicrobial resistance genes, plasmid incompatibility types, and CRISPR-Cas defenses of a linezolid-resistant Enterococcus faecalis isolated in feces from a healthy pig during an antimicrobial surveillance program for animal production in Brazil. The cfr gene was found to be integrated into a transposon-like structure of 7,759 nt flanked by IS1216E and capable of excising and circularizing, distinguishing it from known genetic contexts for cfr in Enterococcus spp., while optrA was inserted into an Inc18 broad host-range plasmid of >58 kb. Conjugal transfer of cfr and optrA was shown by filter mating. The coexistence of cfr and optrA in an E. faecalis isolated from a healthy nursery pig highlights the need for monitoring the use of antibiotics in the Brazilian swine production system for controlling spread and proliferation of antibiotic resistance.

Biogenic synthesis of silver nanoparticles using Brazilian propolis.

Biological methods have been used to synthesize silver nanoparticles through materials such as bacteria, fungi, plants, and propolis due to their reducing properties, stabilizer role and environmentally friendly characteristic. Considering the antimicrobial activity of propolis as well as the broad-spectrum antibacterial effects of silver nanoparticles, this study aim to describe the use of Brazilian propolis to synthesize silver nanoparticles (AgNP-P) and investigate its antimicrobial activity. The synthesis was optimized by factorial design, choosing the best conditions for smaller size particles. AgNP-P demonstrated a maximum absorbance at 412 nm in ultraviolet-visible spectra, which indicated a spherical format and its formation. Dynamic light scattering demonstrated a hydrodynamic size of 109 nm and polydispersity index less than 0.3, showing a good size distribution and stability. After its purification via centrifugation, microscopy analysis corroborates the format and showed the presence of propolis around silver nanoparticle. X-ray diffraction peaks were attributed to the main planes of the metallic silver crystalline structure; meanwhile infrared spectroscopy demonstrated the main groups responsible for silver reduction, represented by ∼22% of AgNP-P indicates by thermal analysis. Our product revealed an important antimicrobial activity indicating a synergism between propolis and silver nanoparticles as expected and promising to be an effective antimicrobial product to be used in infections.