Electrophilically Activated Nitroalkanes in Reactions With Carbon Based Nucleophiles

Unusual reactivity of nitroalkanes, involving formation of aci-forms (nitronic acids or nitronates) and their subsequent interaction with carbon-based nucleophiles, is surveyed in this review.

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.

Probing the influence of protecting groups on the anomeric equilibrium in sialic acid glycosides with the persistent radical effect

A method for the investigation of the influence of protecting groups on the anomeric equilibrium in the sialic acid glycosides has been developed on the basis of the equilibration of O-sialyl hydroxylamines by reversible homolytic scission of the glycosidic bond following the dictates of the Fischer-Ingold persistent radical effect. It is found that a trans-fused 4O,5N-oxazolidinone group stabilizes the equatorial glycoside, i.e., reduces the anomeric effect, when compared to the 4O,5N-diacetyl protected systems. This effect is discussed in terms of the powerful electron-withdrawing nature of the oxazolidinone system, which in turn is a function of its strong dipole moment in the mean plane of the pyranose ring system. The new equilibration method displays a small solvent effect and is most pronounced in less polar media consistent with the anomeric effect in general. The unusual (for anomeric radicals) poor kinetic selectivity of anomeric sialyl radicals is discussed in terms of the planar π-type structure of these radicals and of competing 1,3-diaxial interactions in the diastereomeric transition states for trapping on the α- and β-faces of the radical.

[Features phase transfer catalytic glycosylation of aromatic hydroxy acids]

The catalytic phase transfer reactions of per acetylated alpha-D-glucosaminyl chloride with isomeric hydroxybenzoic, 1-hydroxy-2-naphthoic acids in solid potassium carbonate--acetonitrile were studied. It was found that the composition and yields of reaction products are determined by the nature of the source ofcarboxylic acids, lipophilic phase transfer catalyst, temperature. For the first time found that the O-beta-glycosyl esters of ortho-hydroxyaromatic acids in the presence of potassium carbonate can anomerizovatsya in 1,2-cis derivatives. The structure of the synthesized compounds proved 1H NMR spectroscopy. In in vivo experiments it was established that glycosyl esters of salicylic acid and per acetylated 2-carboxy phenylglucosaminide exhibit analgesic activity similar to aspirin.