Silver complexes antibacterial effects

The use of silver nitrate and colloidal silver in wounds dates from the mid-nineteenth century and the term oligodynamic was applied to the antimicrobial action of heavy metals diluted in water [9]. Over the years, attempts to put silver in contact with wounds produced a number of electrolytic methods [9] as well as use of solutions of silver nitrate, in this case as late as 1965 [16]. However, the imbalance of sodium, potassium and chloride caused by silver nitrate in these cases was unsatisfactory due to the number of resulting side effects. These include in some cases methemoglobinemia from reduction of nitrate to nitrite. In 1968, a complex (AgSD) formed from a sulfonamide and silver was introduced in attempts to combine the oligodynamic action of the heavy metal with the antibacterial effect of the sulfonamide [17]. The insoluble product, which is used as a 1% cream, has suitable properties and excellent wide spectrum antibacterial activity, and is used worldwide for burn prophylaxis and other infectious skin conditions [9]. Side effects are few, the major one being leukopenia. The properties and mode of action of AgSD have been reviewed [9,18]. 

The dissociation of silver may not in some cases be a prerequisite for activity silver uracil complexes did not penetrate cells and the in vitro antibacterial action was attributed to membrane effects [25]. A survey of the in vitro antimicrobial effects of a series of metal sulfanilamides also appointed silver and gold salts as the most active, the gold sulfadiazene being as active as the silver complex [26]. The chemistry and microbiology of these species has been summarized [27]. 

NomiyaK, Takahashi, S andNoguchiR, Synthesis of crystal structure of three silver (I) complexes with (j)-(+)-5-ixi-2-tetrahydrofurancarboxylic acid (S-Hothf) and its isomeric forms (f -Hothf and R, S-Hothf) showing wide spectra of effective antibacterial and antifungal activities. Chiral helical polymers in the solid state formed by self-assembly of the dimeric Aglothefjj cores . Journal of The Chemical Society - Dalton Transactions, 2000, issue 8, 1343-1348. 

It has been reported that silver ion-exchanged zeolites exhibit antibacterial activity [32]. The mechanism of antibacterial action of the zeolite is initiated when moisture or liquid film comes into contact with the ion exchange material and silver ions are exchanged with sodium (Na) or other cations from the environment [33]. The released silver ions attach to the bacteria by forming chelate complexes with deoxyribonucleic acid, which blocks the transport processes in the cell [34]. The use of zeolite as a filler in polymeric materials has been reported in the literature and it has been proved that they enhance the antibacterial activity of the polymer [35]. Furthermore, the effect of zeolite content on the physical and thermal properties of the polymer was also examined [35] increasing the silver/zeolite ratio in the polymer led to an increased antimicrobial activity (due to the higher silver ion concentration), but depending upon the application the zeolite content may influence physical, thermal and/or chemical properties of the polymeric material. 

A prominent FDA-approved chitin dressing is rapid deployment hemo-stat (RDH) (Marine Polymer Technologies) which costs 300 per dressing. One study shows that polymeric hber material based on P-NAG is more effective than alpha-chitin or chitosan, since these have a heterogeneous structure and are complexed with minerals and proteins. Moreover, the j3 structure (parallel orientation) of the hbers was found to be more effective than the a structure (antiparallel orientation). In another study, the hemostatic and antibacterial properties of chitosan dressings have been shown to be improved by the addition of polyphosphate polymers and silver nanoparticles respectively. One limiting factor is that all forms of chitin or chitosan bandages are not equally effective and the effectiveness varies from batch to batch. ... 

Antibacterial complexes such as silver sulfadiazene and some mercurials also manifest antiviral activity [51, 52]. Mersalyl, a diuretic (Chapter 12), has some in vivo action when mice treated with lethal doses of coxsackie virus are then administered the mercury complex [53]. The levels needed for 100% inactivation in vitro by mercurials is dependent on the virus, and thiols reverse the antiviral effect [54]. Conformational changes and breakdown into subunits have also been observed after mercury treatment [51],... 

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