The iodide-catalyzed decomposition of hydrogen peroxide: mechanistic details of an old reaction as revealed by electrospray ionization mass spectrometry monitoring

Dalmázio, Ilza; Moura, Flávia C.C.; Araújo, Maria Helena; Alves, Tânia Maria de Almeida; Lago, Rochel M.; Lima, Guilherme Ferreira de; Duarte, Hélio A.; Augusti, Rodinei

doi:10.1590/s0103-50532008000600008

Cited by 16 publications

(13 citation statements)

References 28 publications

(32 reference statements)

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“…Here it seems clear that potentiation of aPDI by the addition of KI must be due to photogeneration of reactive radicals such as or I 2 •− and HOO • or possibly by decomposition of HOOI − 2 . 33 This conclusion is based upon the following evidence. There was potentiation of killing of MRSA with 10 mM KI in the case of no wash and with 25 mM KI in the case of a wash, whereas there was no potentiation of killing when bacteria were added after light until 100 mM KI is reached.…”

Section: Resultsmentioning

confidence: 97%

“…Considering possible reactive intermediates in these reactions, an interesting paper by Dalmazio et al 33 from Brazil used mass spectrometry and ab initio free energy calculations to study the decomposition of hydrogen peroxide in the presence of iodide anions. They detected a species with m / z 287 that was proposed to be HOOI − 2 and explained its formation as depicted in eq 10 and eq 5.…”

Section: Resultsmentioning

confidence: 99%

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Potassium Iodide Potentiates Broad-Spectrum Antimicrobial Photodynamic Inactivation Using Photofrin

et al. 2017

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It is known that noncationic porphyrins such as Photofrin (PF) are effective in mediating antimicrobial photodynamic inactivation (aPDI) of Gram-positive bacteria or fungi. However, the aPDI activity of PF against Gram-negative bacteria is accepted to be extremely low. Here we report that the nontoxic inorganic salt potassium iodide (KI) at a concentration of 100 mM when added to microbial cells (108/mL) + PF (10 μM hematoporphyrin equivalent) + 415 nm light (10 J/cm2) can eradicate (>6 log killing) five different Gram-negative species (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, and Acinetobacter baumannii), whereas no killing was obtained without KI. The mechanism of action appears to be the generation of microbicidal molecular iodine (I2/I3−) as shown by comparable bacterial killing when cells were added to the mixture after completion of illumination and light-dependent generation of iodine as detected by the formation of the starch complex. Gram-positive methicillin-resistant Staphylococcus aureus is much more sensitive to aPDI (200–500 nM PF), and in this case potentiation by KI may be mediated mainly by short-lived iodine reactive species. The fungal yeast Candida albicans displayed intermediate sensitivity to PF-aPDI, and killing was also potentiated by KI. The reaction mechanism occurs via singlet oxygen (1O2). KI quenched 1O2 luminescence (1270 nm) at a rate constant of 9.2 × 105 M−1 s−1. Oxygen consumption was increased when PF was illuminated in the presence of KI. Hydrogen peroxide but not superoxide was generated from illuminated PF in the presence of KI. Sodium azide completely inhibited the killing of E. coli with PF/blue light + KI.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Potassium Iodide Potentiates Broad-Spectrum Antimicrobial Photodynamic Inactivation Using Photofrin

et al. 2017

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show abstract

“…Dalmázio et al (30) from Brazil used mass spectrometry and ab initio free energy calculations to study the decomposition of hydrogen peroxide in the presence of iodide anions. They detected a species with m/z 287 that was proposed to be HOOI 2 Ϫ .…”

Section: Discussionmentioning

confidence: 99%

Potassium iodide potentiates antimicrobial photodynamic inactivation mediated by Rose Bengal: in vitro and in vivo studies

Wen

Zhang

Szewczyk

et al. 2018

Light-Based Diagnosis and Treatment of Infectious Diseases

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Rose bengal (RB) is a halogenated xanthene dye that has been used to mediate antimicrobial photodynamic inactivation for several years. While RB is highly active against Gram-positive bacteria, it is largely inactive in killing Gram-negative bacteria. We have discovered that addition of the nontoxic salt potassium iodide (100 mM) potentiates green light (540-nm)-mediated killing by up to 6 extra logs with the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, the Gram-positive bacterium methicillin-resistant Staphylococcus aureus, and the fungal yeast Candida albicans. The mechanism is proposed to be singlet oxygen addition to iodide anion to form peroxyiodide, which decomposes into radicals and, finally, forms hydrogen peroxide and molecular iodine. The effects of these different bactericidal species can be teased apart by comparing the levels of killing achieved in three different scenarios: (i) cells, RB, and KI are mixed together and then illuminated with green light; (ii) cells and RB are centrifuged, and then KI is added and the mixture is illuminated with green light; and (iii) RB and KI are illuminated with green light, and then cells are added after illumination with the light. We also showed that KI could potentiate RB photodynamic therapy in a mouse model of skin abrasions infected with bioluminescent P. aeruginosa.

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“…The proposed mechanism follows Eqs. (1) and (2) in aqueous solution 27,28 : ( Supplementary Fig. 4).…”

Section: Resultsmentioning

confidence: 99%

Suppressing hydrogen peroxide generation to achieve oxygen-insensitivity of a [NiFe] hydrogenase in redox active films

Münchberg

Oughli

et al. 2020

Nat Commun

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Redox-active films were proposed as protective matrices for preventing oxidative deactivation of oxygen-sensitive catalysts such as hydrogenases for their use in fuel cells. However, the theoretical models predict quasi-infinite protection from oxygen and the aerobic half-life for hydrogenase-catalyzed hydrogen oxidation within redox films lasts only about a day. Here, we employ operando confocal microscopy to elucidate the deactivation processes. The hydrogen peroxide generated from incomplete reduction of oxygen induces the decomposition of the redox matrix rather than deactivation of the biocatalyst. We show that efficient dismutation of hydrogen peroxide by iodide extends the aerobic half-life of the catalytic film containing an oxygen-sensitive [NiFe] hydrogenase to over one week, approaching the experimental anaerobic half-life. Altogether, our data support the theory that redox films make the hydrogenases immune against the direct deactivation by oxygen and highlight the importance of suppressing hydrogen peroxide production in order to reach complete protection from oxidative stress.

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The iodide-catalyzed decomposition of hydrogen peroxide: mechanistic details of an old reaction as revealed by electrospray ionization mass spectrometry monitoring

Cited by 16 publications

References 28 publications

Potassium Iodide Potentiates Broad-Spectrum Antimicrobial Photodynamic Inactivation Using Photofrin

Potassium Iodide Potentiates Broad-Spectrum Antimicrobial Photodynamic Inactivation Using Photofrin

Potassium iodide potentiates antimicrobial photodynamic inactivation mediated by Rose Bengal: in vitro and in vivo studies

Suppressing hydrogen peroxide generation to achieve oxygen-insensitivity of a [NiFe] hydrogenase in redox active films

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