Antimicrobial Effects of Silver Nanoparticles Stabilized in Solution by Sodium Alginate.

BACKGROUND/PURPOSE: To investigate the effect of nanosilver particles in solution stabilized in a matrix of sodium alginate on the growth and development of pathogenic bacteria such as Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Proteus vulgaris, Enterobacter cloacae, the antibiotic-resistant strain of Pseudomonas aeruginosa, the yeast-like fungus Candida albicans, and the luminescent bacteria Photobacterium leiognathi Sh1. METHODS: Isolates of pathogenic bacteria obtained from bronchoalveolar and peritoneal lavage samples from Wistar rats with experimental pneumonia and peritonitis were tested for their susceptibility to silver nanoparticles in solution with an alginate stabilizer. The antifungal activity of silver nanoparticles in sodium alginate was studied for C. albicans (strain CCM885) using the Sabouraud agar method. The biocidal impact of silver nanoparticles in solution with a sodium alginate matrix on the luminescent bacteria P. leiognathi Sh1 was investigated using a BLM 8801 luminometer. RESULTS: It was observed that a 0.02-0.05% nanosilver solution with an alginate stabilizer limits the growth and development of pathogenic bacteria within the first 24 hours of exposure. If the concentration of nanosilver solution is 0.0005-0.05%, it inhibits the viability of the fungus C. albicans. A nanosilver solution at a concentration of 0.05-0.2 µg/mL represses bioluminescence in the bacteria P. leiognathi Sh1. From these results, it appears that the biocidal effect of nanosilver is related either to the presence of ions that are formed during dissolution, or to the availability of nanoparticles that interrupt the membrane permeability of bacterial cells. CONCLUSION: Silver nanoparticles stabilized in a solution of sodium alginate possess significant in vitro antimicrobial activity, which is manifested by inhibition of the bioluminescence of P. leiognathi Sh1, and inhibition of the growth and development of the pathogenic bacteria S. aureus, E. faecalis, E. coli, P. vulgaris, E. cloacae, the antibiotic-resistant strain of P. aeruginosa, and the fungus C. albicans.

1-R-2-([1,2,4]Triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s: Synthesis, Bioluminescence Inhibition, Molecular Docking Studies, Antibacterial and Antifungal Activities.

The increasing mortality due to antibacterial resistance necessitates the search for novel antimicrobial agents. Hence, series of 1-R-2-([1,2,4]triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s were synthesized, evaluated by spectral data and studied against St. aureus, M. luteum, E. faecalis, E. aerogenes, P. aeruginosa, C. sakazakii, E. coli, K. pneumonia, hospital Streptococcus spp., C. albicans and A. niger in 100, 500 µg/mL and 100 µg/disk. Substances exhibited moderate toxicity in 0.025, 0.1 and 0.25 mg/mL in bioluminescence inhibition tests of Photobacterium leiognathi. SAR exposed that introduction of 2,4-(Cl)2C6H3-, 2,5-(OMe)2C6H3-, 4-Me-2-iPr-C6H3O- and 3-iPr-C6H4O- fragments and reduction of the pyrimidine ring of R-([1,2,4]triazolo[1,5-c]quinazolin-2-ylthio)alcohols were the best modifications to promote antimicrobial activity. Molecular docking showed their good affinity into the active sites of EcPanK-AMPPNP and hDHFR. Hence, reported results will be used for subsequent QSAR model creation and purposeful antimicrobial modification of the strongest compounds.

1-R-2-([1,2,4]Triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s: synthesis, bioluminescence inhibition, molecular docking studies, antibacterial and antifungal activity.

The increasing mortality due to antibacterial resistance necessitates the search for novel antimicrobial agents. Hence, series of 1-R-2-([1,2,4]triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s were synthesized, evaluated by spectral data and studied against St. aureus, M. luteum, E. faecalis, E. aerogenes, P. aeruginosa, C. sakazakii, E.coli, K. pneumonia, hospital Streptococcus spp., C. albicans and A. niger in 100, 500 µg/mL and 100 µg/disk. Substances exhibited moderate toxicity in 0.025, 0.1 and 0.25 mg/mL in bioluminescence inhibition tests of Photobacterium leiognathi. SAR exposed that introduction of 2,4-(Cl)2C6H3-, 2,5-(OMe)2C6H3-, 4-Me-2-iPr-C6H3O- and 3-iPr-C6H4O- fragments and reduction of the pyrimidine ring of R-([1,2,4]triazolo[1,5-c]quinazolin-2-ylthio)alcohols were the best modifications to promote antimicrobial activity. Molecular docking showed their good affinity into the active sites of EcPanK-AMPPNP and hDHFR. Hence, reported results will be used for subsequent QSAR model creation and purposeful antimicrobial modification of the strongest compounds.

Synthesis, cytotoxicity by bioluminescence inhibition, antibacterial and antifungal activity of ([1,2,4]Triazolo[1,5-c]quinazolin-2-ylthio)carboxylic acid amides.

We report in this work the synthesis, cytotoxicity, and antimicrobial activity of ([1,2,4]triazolo[1,5-c]quinazolin-2-ylthio)carboxylic acid amides 4-7 in connection with our previous research in the preparation of triazoloquinazoline derivatives. Due to simplicity, general availability of starting materials, and high yields, the most reliable method of synthesis appeared to be the one with N,N-carbonyldiimidazole activation stage. The chemical structures of all obtained substances were deduced from FT-IR, (1)H-NMR, EI-MS, and LC-MS spectral data. The results of cytotoxicity evaluated by bioluminescence inhibition of bacterium Photobacterium leiognathi, strain Sh1 showed that compounds 4.1, 4.6, and 6.1 were the most cytotoxic. Investigation of the antimicrobial and antifungal activity of amides 4-7 (concentration 5 mg/mL) was carried out by the stiff-plate agar-diffusion method. We found that the compounds possessed low (4.1, 4.7) antifungal activity against Candida tenuis and strong (4.21, 5.1, 5.9) or inefficient (4.7, 4.12, 4.16) activity against Aspergillus niger. Substances 5.1 and 5.9 slightly affected Mycobacterium luteum. Staphylococcus aureus was resistant to all obtained substances, and only the n-butyramide derivatives 7.1 and 7.5 inhibited the growth of Escherichia coli. Hence, there was no strong correlation between bioluminescence inhibition and antimicrobial activity of the investigated substances.

Synthesis of new 2-thio-[1,2,4]triazolo[1,5-c]quinazoline derivatives and its antimicrobial activity.

A series of novel ([1,2,4]triazolo[1,5-c]quinazolin-2-ylthio)carboxylic acids 2a-d and esters 3a-l were synthesized and evaluated for antimicrobial activity. Alkylation of potassium 2-thio-[1,2,4]triazolo[1,5-c]quinazoline 1 with halogenocarboxylic acids and its esters proceeded S-regioselectively. During acid catalyzed esterification of 2a-c, degradation of the pyrimidine ring was observed. The structures of the compounds were elucidated by FT-IR, (1)H- and (13)C-NMR, electron impact mass spectra (EI-MS) and LC-MS spectral data. Antimicrobial and antifungal activity of synthesized compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, Mycobacterium luteum, Candida albicans and Candida tenuis. Acids 2a and 2c exhibited significant activity against C. albicans, which was additionally confirmed by the bioluminescence inhibition test and interrelated with their lipophilicity.