Nitrite antimicrobial effects

Dykhuizen R., Frazer R., Benjamin N., Duncan C., Smith C.C., Golden M. and Leifert C. (1996). Antimicrobial effect of acidified nitrite on gut pathogens the importance of dietary nitrate in host defence . J Antimicrob Agents Chemothe, 40, 1422-1425. 

Reddy et al. (1983) concluded that NO inactivation of iron-sulfur proteins was the probable mechanism of botulinal inhibition in nitrite-tteated foods. In support of this conclusion, Carpenter et al. (1987) observed decreased activity of clostridial pyruvate-ferredoxin oxidoteductase and lower cytochrome c reducing ability by ferredoxin in extracts of cells treated with nitrite. NO tteatment also inhibits yeast pyruvate decarboxylase (a non-iron-sulfur protein) and py-ruvate-ferredoxin oxidoteductase from C. perfringens (McMindes and Siedler, 1988). They suggested that thiamine-dependent decarboxylation of pyruvate may be an additional site for antimicrobial effects of NO. 

Based on the incomplete inhibition of iron-sulfur proteins by nitrite, and the observation that low-spin Fe—NO EPR signals were observed by C. sporogenes cultures that recovered from nitrite treatment, Payne et al. (1990a) concluded that the antimicrobial effect of nitrite or NO cannot be explained by direct inhibition of preformed pyruvate—ferredoxin oxidoreductase or hydrogenase. 

Ashworth, J., Hargreaves, L. L., and Jarvis, B. (1973). The production of an antimicrobial effect in pork heated with sodium nitrite under simulated commercial pasteurization conditions. J. Food Technol. 8, 477-484. 

Fite, A., Dykhuizen, R., Litterick, A., Golden, M., and Leifert, C. 2004. Effects of ascorbic acid, glutathione, thiocyanate, and iodide on antimicrobial activity of acidified nitrite. Antimicrobial Agents and Chemotherapy 48 655-658. 

Developing alternatives to nitrite is extremely difficult because of its many functions in food including its antimicrobial effect against C. botuli-num, its role in the formation of the characteristic colour of cured meats, its antioxidant activity that prevents the formation of off-flavours and its contribution to the characteristic flavour and texture of cured meats. 

Phenols are rather common antimicrobial components of metalworking fluids however, their use in recent years has been declining (36). The inhibition of nitrosation by phenols has recently been reviewed (35). In general, phenolic compounds inhibit nitrosation by reacting with nitrite (phenol reacts with nitrite 10,0 0 0 times faster than with dimethylamine), but the intermediate nitrosophenolis unstable and enhances nitrosation. "The overall effect is dependent on the steady state concentration of the nitrosophenol and the relative degrees of retardation and enhancement exerted by the phenol and the nitrosophenol, respectively ( 35)". 

Some antioxidants possess antimicrobial properties, such as propyl gallate and butylated hydroxy anisole, which are somewhat effective against bacteria. Butylated hydroxy toluene has demonstrated some antiviral activity. Compatibility of antioxidants with the drug, packaging system and the body should be studied carefully. For example, tocopherols may be absorbed onto plastics ascorbic acid is incompatible with alkalis, heavy metals, and oxidizing materials such as phenylephrine, and sodium nitrite and propyl gallate forms complexes with metal ions such as sodium, potassium and iron. 

The effectiveness of the antimicrobial activity can be enhanced by combining zinc citrate with triclosan [22-24]. Triclosan, or 2,4,4 -trichloro-2-hydroxy diphenyl ether, is an aromatic, trichlorinated synthetic componnd. It can be obtained by reaction of 2,4-dichlorophenol with 2,5-dichloronitrobenzene in the presence of alkali and reduction of the 2,4,4 -trichloro-2 -nitrodiphenyl ether into 2,4,4 -trichloro-2 -aminodiphenyl ether. This is diazotized with sodium nitrite with excess sulfnric acid. After hydrolization, 2,4,4 -trichloro-2 -hydroxydiphenyl ether is extracted with xylene and purified [20-25]. 

Sulphur dioxide (SO2) is another multifunctional additive that is antimicrobial and effective against most bacteria. It has found use in wine, beer, biscuit dough, dried and cut vegetables and fruit. Consumer concern about SO2 in foods has resulted in alternatives being sought and used but, like nitrite, sulphur dioxide is not easy to replace in foods so usually a combination of additives must be used in its place (see section 6.4). 

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]. 

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