Bioactive Selenium Nanoparticles Synthesized from Propolis Extract and Quercetin Based on Natural Deep Eutectic Solvents (NDES)

This study presents the process of obtaining of antimicrobial selenium nanoparticles in propolis extract and quercetin using natural deep eutectic solvents (NDES). The extraction using NDES as solvent makes it possible to obtain extracts with a higher content of active compounds compared to extraction with water, especially as it concerns compounds with limited solubility in water. Based on the results, the highest content of flavonoids, terpenes and antioxidant activity were found in the propolis extract with the applied NDES citric acid-propanediol-proline. The total phenolic content of propolis extracts ranged from about 30 to 200 mg/g dry weight, and the flavonoid content ranged from about 3 to 70 mg quercetin equivalents. Spherical selenium nanoparticles obtained from propolis extract had a particle size of 279 nm, while Se NPs obtained from quercetin dissolved in NDES had a particle size of about 96.0 nm. Se NPs obtained in the presence of both quercetin and propolis extract had high antioxidant activity. The activity of selenium nanoparticles synthesized using propolis was confirmed against E. coli, P. aeruginosa, S. aureus and C. albicans . The MBC of the microorganisms were 25, 100, 100 and 25 mg/l, respectively for E. coli, P. aeruginosa, S. aureus and C. albicans .