Free radical production from the aerobic oxidation of reduced pyridine nucleotides catalysed by phenazine derivatives

Davis, Graham; Thornalley, Paul J.

doi:10.1016/0005-2728(83)90106-8

Cited by 56 publications

(27 citation statements)

References 12 publications

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“…The theoretical Q Ext values are expressed in arbitrary units. Experimental SPR spectra due to pyocyanin-mediated reduction of Ag ϩ were determined by incubating AgNO 3 (100 M) with pyocyanin (5 M) and NADPH (100 M) as the source of reducing equivalents (23) in water (pH 7.0; 32°C; 18 M⍀ · cm Ϫ1 ) followed by scanning spectrophotometry to observe the emergence of SPR bands associated with nanoparticulate Ag 0 formation. The experimental Q Ext values are expressed in real units.…”

Section: Methodsmentioning

confidence: 99%

Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

Müller

Merrett

2014

Antimicrob Agents Chemother

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Silver in its ionic form (Ag ؉ ), but not the bulk metal (Ag 0 ), is toxic to microbial life forms and has been used for many years in the treatment of wound infections. The prevalence of bacterial resistance to silver is considered low due to the nonspecific nature of its toxicity. However, the recent increased use of silver as an antimicrobial agent for medical, consumer, and industrial products has raised concern that widespread silver resistance may emerge. Pseudomonas aeruginosa is a common pathogen that produces pyocyanin, a redox toxin and a reductant for molecular oxygen and ferric (Fe 3؉ ) ions. The objective of this study was to determine whether pyocyanin reduces Ag ؉ to Ag 0 , which may contribute to silver resistance due to lower bioavailability of the cation. Using surface plasmon resonance spectroscopy and scanning electron microscopy, pyocyanin was confirmed to be a reductant for Ag ؉ , forming Ag 0 nanoparticles and reducing the bioavailability of free Ag ؉ by >95% within minutes. Similarly, a pyocyanin-producing strain of P. aeruginosa (PA14) reduced Ag ؉ but not a pyocyanin-deficient (⌬phzM) strain of the bacterium. Challenge of each strain with Ag ؉ (as AgNO 3 ) gave MICs of 20 and 5 g/ml for the PA14 and ⌬phzM strains, respectively. Removal of pyocyanin from the medium strain PA14 was grown in or its addition to the medium that ⌬phzM mutant was grown in gave MICs of 5 and 20 g/ml, respectively. Clinical isolates demonstrated similar pyocyanin-dependent resistance to Ag ؉ . We conclude that pseudomonal silver resistance exists independently of previously recognized intracellular mechanisms and may be more prevalent than previously considered.

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Section: Methodsmentioning

confidence: 99%

Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

Müller

Merrett

2014

Antimicrob Agents Chemother

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“…PCN’s induction of oxidative stress is, at least in part, due to its ability to increase intracellular levels of reactive oxygen species (ROS), in particular superoxide (O 2 · − ) [10,11,12,17,25,34,35] and hydrogen peroxide (H 2 O 2 ) [25,36]. These increases are mediated by dismutase and under aerobic conditions, H 2 O 2 and O 2 · − and are formed by cyclic non-enzymatic reduction by NAD(P)H [12,17,34] with PCN accepting electrons from NAD(P)H [10,11,12].…”

Section: Role Of Oxidative Stress In Pyocyanin’s Toxicitymentioning

confidence: 99%

Cellular Effects of Pyocyanin, a Secreted Virulence Factor of Pseudomonas aeruginosa

Hall

McDermott

Anoopkumar‐Dukie

et al. 2016

Toxins

336

254

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Pyocyanin has recently emerged as an important virulence factor produced by Pseudomonas aeruginosa. The redox-active tricyclic zwitterion has been shown to have a number of potential effects on various organ systems in vitro, including the respiratory, cardiovascular, urological, and central nervous systems. It has been shown that a large number of the effects to these systems are via the formation of reactive oxygen species. The limitations of studies are, to date, focused on the localized effect of the release of pyocyanin (PCN). It has been postulated that, given its chemical properties, PCN is able to readily cross biological membranes, however studies have yet to be undertaken to evaluate this effect. This review highlights the possible manifestations of PCN exposure; however, most studies to date are in vitro. Further high quality in vivo studies are needed to fully assess the physiological manifestations of PCN exposure on the various body systems.

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“…A phenazine-water complex has been shown to abstract an electron from DNA bases in isolation (Choudhury and Basu, 2005). Some phenazine derivatives can be very active as redox agents (Davis and Thornalley, 1983). In the case of phenazine methosulfate, a radical cation is produced as it oxidizes reduced pyridine nucleotides within cells.…”

Section: Toxicological Evaluation Of Phenazine and Chlorophenazinesmentioning

confidence: 99%

Potential carcinogenic hazards of non-regulated disinfection by-products: Haloquinones, halo-cyclopentene and cyclohexene derivatives, N-halamines, halonitriles, and heterocyclic amines

Bull¹,

et al. 2011

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Drinking water disinfectants react with natural organic material (NOM) present in source waters used for drinking water to produce a wide variety of by-products. Several hundred disinfection by-products (DBPs) have been identified, but none have been identified with sufficient carcinogenic potency to account for the cancer risks projected from epidemiological studies. In a search for DBPs that might fill this risk gap, the present study projected reactions of chlorine and chloramine that could occur with substructures present in NOM to produce novel by-products. A review of toxicological data on related compounds, supplemented by use of a quantitative structure toxicity relationship (QSTR) program TOPKAT® identified chemicals with a high probability of being chronically toxic and/or carcinogenic among 489 established and novel DBPs. Classes of DBPs that were specifically examined were haloquinones (HQs), related halo-cyclopentene and cyclohexene (HCP&H) derivatives, halonitriles (HNs), organic N-chloramines (NCls), haloacetamides (HAMs), and nitrosamines (NAs). A review of toxicological data available for quinones suggested that HQs and HCP&H derivatives appeared likely to be of health concern and were predicted to have chronic lowest observed adverse effect levels (LOAELs) in the low μg/kg day-1 range. Several HQs were predicted to be carcinogenic. Some have now been identified in drinking water. The broader class of HNs was explored by considering current toxicological data on haloacetonitriles and extending this to halopropionitriles. 2,2-Dichloropropionitrile has been identified in drinking water at low concentrations, as well as the more widely recognized haloacetonitriles. The occurrence of HAMs has been previously documented. The very limited toxicological data on HAMs suggests that this class would have toxicological potencies similar to the dihaloacetic acids. Organic N-halamines are also known to be produced in drinking water treatment and have biological properties of concern, but no member has ever been characterized toxicologically beyond bacterial or in vitro studies of genotoxicity. The documented formation of several nitrosamines from secondary amines from both natural and industrial sources prompted exploration of the formation of additional nitrosamines. N-Diphenylnitrosamine was identified in drinking waters. Of more interest, however, was the formation of phenazine (and subsequently N-chorophenazine) in a competing reaction. These are the first heterocyclic amines that have been identified as chlorination by-products. Consideration of the amounts detected of members of these by-product classes and their probable toxicological potency suggest a prioritization for obtaining more detailed toxicological data of HQs > HCP&H derivatives > NCls > HNs. Based upon a ubiquitous occurrence and virtual lack of in vivo toxicological data, NCls are the most difficult group to assign a priority as potential carcinogenic risks. This analysis indicates that research on the general problem of DBPs re...

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Free radical production from the aerobic oxidation of reduced pyridine nucleotides catalysed by phenazine derivatives

Cited by 56 publications

References 12 publications

Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

Cellular Effects of Pyocyanin, a Secreted Virulence Factor of Pseudomonas aeruginosa

Potential carcinogenic hazards of non-regulated disinfection by-products: Haloquinones, halo-cyclopentene and cyclohexene derivatives, N-halamines, halonitriles, and heterocyclic amines

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