Objective. To evaluate the antimicrobial activity of soft and purified propolis extracts. Study object and methods. Antimicrobial activity of soft and purified propolis extracts was determined with reference cultures of Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 33499, Pseudomonas aeruginosa ATCC 27853, Proteus mirabilis ATCC 12459, Bacillus subtilis ATCC 6633, Bacillus cereus ATCC 8035, and fungus Candida albicans ATCC 60193. Microbiological tests were performed under aseptic conditions. Minimum inhibitory concentration (MIC) – the highest dilution of preparation (the lowest concentration of preparation) that suppresses growth of reference microorganisms – was determined. Results. Concentration of phenolic compounds in soft propolis extract that possesses antimicrobial activity against gram-positive (Staphylococcus aureus, Enterococcus faecalis) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis) is 0.587±0.054 mg and 0.587±0.054–0.394±0.022 mg (P>0.05) and in purified propolis extract – 0.427±0.044 mg and 0.256±0.02 mg (P>0.05). Klebsiella pneumoniae is most resistant to soft propolis extract when the concentration of phenolic compounds is 1.119± 0.152 mg and to purified propolis extract when the concentration of phenolic compounds is 1.013±0.189 mg (P>0.05). Spore-forming Bacillus subtilis bacteria are more sensitive to soft and purified propolis extracts when the concentration of phenolic compounds is 0.134±0.002 mg and 0.075±0.025 mg, respectively, and Bacillus cereus – when the concentration is 0.394±0.022 mg and 0.256±0.02 mg (P>0.05). Sensitivity of fungus Candida albicans to soft and purified propolis extracts is the same as Bacillus subtilis. Encapsulated bacterium Klebsiella pneumoniae is most resistant to antimicrobial action of soft and purified propolis extracts as compared with gram-positive Staphylococcus aureus and Enterococcus faecalis bacteria (P<0.05), gram-negative Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis (P<0.05), sporeforming Bacillus subtilis and Bacillus cereus bacteria (P<0.05), and fungus Candida albicans (P<0.05). There is no statistically significant difference between antimicrobial effect of soft propolis extract and purified propolis extract on gram-positive bacteria, gram-negative bacteria, spore-forming bacteria, encapsulated bacteria, and Candida fungus. Conclusions. Soft and purified propolis extracts possess antimicrobial activity. They could be recommended as natural preservatives in the manufacture of pharmaceutical products.

Enzyme-assisted extraction is a valuable tool for mild and environmentally-friendly extraction conditions to release bioactive compounds and sugars, essential for silver nanoparticle (AgNP) green synthesis as capping and reducing agents. In this research, plant and fungal kingdoms were selected to obtain the enzyme-assisted extracts, using green synthesized AgNPs. For the synthesis, pseudo-cereal Fagopyrum esculentum (F. esculentum) and lichen Certaria islandica (C. islandica) extracts were used as environmentally-friendly agents under heating in an aqueous solution. Raw and enzyme-assisted extracts of AgNPs were characterized by physicochemical, phytochemical, and morphological characteristics through scanning and transmission electron microscopy (SEM and TEM), as well as Fourier transform infrared spectroscopy (FTIR). The synthesized nanoparticles were spherical in shape and well dispersed, with average sizes ranging from 10 to 50 nm. This study determined the total phenolic content (TPC) and in vitro antioxidant activity in both materials by applying standard methods. The results showed that TPC, ABTS•+, FRAP, and DPPH• radical scavenging activities varied greatly in samples. The AgNPs derived from enzymatic hydrolyzed aqueous extracts C. islandica and F. esculentum exhibited higher antibacterial activity against the tested bacterial pathogens than their respective crude extracts. Results indicate that the extracts’ biomolecules covering the AgNPs may enhance the biological activity of silver nanoparticles and enzyme assistance as a sustainable additive to technological processes to achieve higher yields and necessary media components.

Ring closure reactions O 0130Synthesis of Azole Derivatives from 3-Phenylaminopropanohydrazide and Evaluation of Their Antimicrobial Efficacy. -Five-membered heterocyclic compounds are constructed through direct transformations or via intermediate semicarbazides.Thus, pyrazole and pyrrole derivatives (IX) and (XI) having a phenylaminopropanoyl moiety are prepared from phenylaminopropanohydrazide (I) by condensation with diketones (VIII) and (X), resp. Intramolecular cyclization reaction of semicarbazides (III) and (XIII) or carbamoyl derivative (VI) afford new triazole (IV) and (XV), oxadiazole (V) and (VII), and thiadiazole (XIV) compounds. (V), (VII), and (XIV) exhibit in vitro antimicrobial activity. -(TUMOSIENE, I.; KANTMINIENE, K.; PAVILONIS, A.; MAZELIENE

No abstract

As antimicrobial drugs destroy microorganisms or stop their growth, they are used to treat infections. Due to the increasing resistance of infectious agents to antimicrobial drugs, there is a need to find new natural products with antimicrobial properties. Natural products such as bee products honey, propolis, pollen, bee bread, and royal jelly are important products with numerous different active biological features, antimicrobial and antiviral among them. The aim of this study was to investigate the antimicrobial effect of royal jelly, honey, and the mixture of honey and royal jelly on gram-positive and gram-negative bacteria, spore bacteria, and the fungus Candida albicans. Royal jelly and honey were collected in Lithuanian apiaries. The antimicrobial activity of royal jelly, honey, and honey-royal jelly mixture (9% solution) was determined using the ‘well’ method of diffusion into agar. Reference cultures of gram-positive and gram-negative bacteria, spore bacteria, and the fungus Candida albicans were used in the study. Royal jelly was found to be the most effective against Staphylococcus epidermidis and Enterococcus faecalis. Royal jelly had the strongest antibacterial effect on Enterococcus faecalis, honey on Listeria monocytogenes and Staphylococcus aureus, and the mixture of honey-royal jelly on S. epidermidis. Royal jelly, honey, and honey-royal jelly solutions were not antibacterial against Proteus vulgaris. Royal jelly, honey, and honey-royal jelly had a weak effect on Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Royal jelly had no effect on Bacillus subtilis, Bacillus cereus, and Candida albicans, and the antibacterial effect of honey and honey-royal jelly mixture was weak. Royal jelly, honey, honey-royal jelly mixture had the strongest effect on gram-positive bacteria. A weaker antimicrobial effect was observed against gram-negative bacteria, spore bacteria, and C. albicans. Royal jelly had no effect on P. vulgaris, and honey-royal jelly mixture had similar antimicrobial activity to honey.