Iodine antimicrobial activity

Povidone—iodine is a brown, water-soluble powder containing approximately 10% iodine. However, the amount of free iodine, which is responsible for the antimicrobial activity, is low in a concentrated solution, but is released as the solution is diluted (41). Concentrated solutions have actually been contaminated with bacteria (42). For use as an antiseptic, povidine—iodine is diluted with water or alcohol to a concentration of 1% iodine. Detergents are added if it is used as a surgical scmb. lodophors are important as broad-spectmm antiseptics for the skin, although they do not have the persistent action of some other antiseptics. They are also used as disinfectants for clinical thermometers that have been used by tuberculous patients, for surface disinfection of tables, etc, and for clean equipment in hospitals, food plants, and dairies, much as chlorine disinfectants are used. 

The antimicrobial activity of iodine is less dependent than chlorine on temperature and pH, though alkaline pH should be avoided. Iodine is also less susceptible to inactivation by organic matter. Disadvantages in the use of iodine in skin antisepsis are staining of skin and fabrics coupled with possible sensitizing of skin and mucous membranes. 

When iodine and povidone are combined, a chemical reaction takes place forming a complex between the two entities. Some of the iodine becomes organically linked to povidone though the major portion of the complexed iodine is in the form of tri-iodide. Dilution of this iodophor results in a weakening of the iodine linkage to the carrier polymer with concomitant increases in elemental iodine in solution and antimicrobial activity. 

As is apparent from the above information, there is no ideal disinfectant, antiseptic or preservative. All chemical agents have their limitations either in terms of their antimicrobial activity, resistance to organic matter, stability, incompatibility, irritancy, toxicity or corrosivity. To overcome the limitations of an individual agent, formulations consisting of combinations of agents are available. For example, ethanol has been combined with chlorhexidine and iodine to produce more active preparations. The combination of chlorhexidine and cetrimide is also considered to improve activity. QACs and phenols have been combined with glutaraldehyde so that the same effect can be achieved with lower, less irritant concentrations of glutaraldehyde. Some... 

The most widely used and effective disinfectant solutions are based on iodine (iodophor) with concentrations ranging between 0.05% and 0.1%, but sometimes higher concentrations are recommended. Other agents such as chlorhexidine or chlorine dioxide, peroxide, sodium chloride and lactic acid may also be effective (Wilson et al., 1997) but are not common. Recent trials show positive effects of aloe vera-based dipping agents (Leon et al., 2004). One problem of iodine containing products is their low pH value (<4.0), which is necessary for their antimicrobial activity (Hansen and Hamann, 2003). 

Kristinsson KG, Jansen B, Treitz U et al. (1991) Antimicrobial activity of polymers coated with iodine-complexed polyvinylpyrrolidone. J Biomater Appl 5 173-184... 

Polyoxyethylene stearates are unstable in hot alkaline solutions owing to hydrolysis, and will also saponify with strong acids or bases. Discoloration or precipitation can occur with salicylates, phenolic substances, iodine salts, and salts of bismuth, silver, and tannins.Complex formation with preservatives may also occur. The antimicrobial activity of some materials such as bacitracin, chloramphenicol, phenoxymethylpenicillin, sodium penicillin, and tetracycline may be reduced in the presence of polyoxyethylene stearate concentrations greater than 5% w/w. ... 

Although all methods were initially comparable, with bacterial reductions of greater than 99%, recolonization of a test site was significantly reduced after 60 minutes when prepared with an alcohol and iodophor drape, compared with the other methods. Jeng and Severin investigated the performance of a povidone-iodine gel alcohol (5% povidone-iodine and 62% ethanol in gel form) as a 30-second, one-time application preoperative skin preparation [20]. The povidone-iodine gel alcohol formulation delivered rapid and persistent antimicrobial activity against a broad spectrum of bacteria, both in vitro and in vivo, and was found to be an effective skin preparation formulation for use in a single-step 30-second application. 

Allyl protecting groups are advantageous in the synthesis of penicillin N and isopenicillin N <0017601 >. Further investigations and evaluation of the azomethine ylide strategy for bicyclic P-lactam synthesis have been reported <01 JCS(P1)1281>. The bicycles 87 (R = OMe or A-phthalimido) are obtained by the action of iodine on compounds 86, which are reported to possess potent antimicrobial activity <00T5571>. 

Pumyani and Singh [28] described the synthesis of iodine-containing quaternary amine methacrylate (QAMA) copolymers. The monomers were prepared via a two-step reaction i) the reaction of ethylene glycol dimethacrylate with piperazine in methanol at 35 °C and ii) the quaternisation of the synthesised monomer with 1-iodooctane. The antimicrobial activities of the QAMA-containing copolymers were evaluated against Escherichia coli and Staphylococcus aureus. 

PVP-iodine is an iodophor, in other words tamed iodine. That means the disadvantages of free iodine (i.e. unpleasant odour, skin irritations, staining of tissue and corrosion of metal surfaces) are diminished. On dilution in water the complex releases, I2, HOI, OI and I3 which are responsible for the antimicrobial activity of PVP-iodine. However, iodine is by far not as reactive as the remaining halogens. 

A poly( -vinyl-2-pyrroHdinone)-iodine complex [25655-41-8] (PVP-iodine), has been used extensively in hospitals and elsewhere because of its germicidal, bactericidal, fungicidal, and generally disinfecting properties (150). It is sold as a solution that contains about 10% available, or active, iodine and about 5% inactive iodine, in the form of iodide ion (see Disinfectants and antiseptics Industrial antimicrobial agents). 

A method for producing an improved antimicrobial material is disclosed whereby a soft, diy, iodine/acetalised polyviityl alcohol complex sponge material is produced which has a pleasing yellow-gold colouration indicating activation of the antimicrobial elements in the complex. 

CS, which is natural polymer containing active groups, such as -NH2, can be functionalised to introduce new positively charged N-atoms. The CS-iodine complexes exhibit better antimicrobial properties. 

Iodine is known for its broad spectrum of antimicrobial and antiviral activity it kills aU known microflora. The need to unveil the details of the interaction of iodine complexes with biomolecules has grown considerably in recent years. On the one hand, this is due to the search for the interrelationship between the characteristics of donor-acceptor complexes and physiological and biological activity of their constituent molecules. On the other hand, it is because of successful developments of a number of biologically active compounds and drugs containing iodine complexes. 

There is general agreement that free molecular iodine represents the real active iodine species which is based on the frequently observed positive correlation between equilibrium concentration of I2 and the rate of microbial extermination [46]. Furthermore, it is an important parameter for toxicity related features like skin irritation. Triiodide is non-toxic and does not have antimicrobial properties. Importantly, selection of equilibrium concentrations of molecular iodine and triiodide can reduce toxicity while retaining antimicrobial properties. 

Remarkably, the presence in solution of the dmg of I2 molecules and 13 ions affect drug s biological properties such as toxicity, irritation [44, 46]. Selection of equilibrium concentrations of molecular iodine and triiodide can reduce toxicity while retaining antimicrobial properties. The reviewed studies could shed a light on such phenomena. One assumes that involvement of a-dextrins in the mixture ensure the presence of the three active centers located within the a-dextrin helix molecular iodine coordinated lithium halogenides and polypeptides, triiodide and lithium halogenides. We believe that the existence of two complexes of iodine and triiodide reduces toxicity of the dmgs [17-20]. 

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