Peroxone chemistry: formation of H2O3 and ring-(HO2)(HO3) from O3/H2O2

Essential Protective Role of Catalytically Active Antibodies (Abzymes) with Redox Antioxidant Functions in Animals and Humans

During the life of aerobic organisms, the oxygen resulting from numerous reactions is converted into reactive oxygen species (ROS). Many ROS are dangerous due to their high reactivity; they are strong oxidants, and react with various cell components, leading to their damage. To protect against ROS overproduction, enzymatic and non-enzymatic systems are evolved in aerobic cells. Several known non-enzymatic antioxidants have a relatively low specific antioxidant activity. Superoxide dismutases, catalase, glutathione peroxidase, glutathione S-transferase, thioredoxin, and the peroxiredoxin families are the most important enzyme antioxidants. Artificial antibodies catalyzing redox reactions using different approaches have been created. During the past several decades, it has been shown that the blood and various biological fluids of humans and animals contain natural antibodies that catalyze different redox reactions, such as classical enzymes. This review, for the first time, summarizes data on existing non-enzymatic antioxidants, canonical enzymes, and artificial or natural antibodies (abzymes) with redox functions. Comparing abzymes with superoxide dismutase, catalase, peroxide-dependent peroxidase, and H₂O₂-independent oxidoreductase activities with the same activities as classical enzymes was carried out. The features of abzymes with the redox activities are described, including their exceptional diversity in the optimal pH values, dependency and independence on various metal ions, and the reaction rate constants for healthy donors and patients with different autoimmune diseases. The entire body of evidence indicates that abzymes with redox antioxidant activities existing in the blood for a long time compared to enzymes are an essential part of the protection system of humans and animals from oxidative stress.

Mechanism and kinetics for the reaction of methyl peroxy radical with O2

Quantum chemical calculations and dynamics simulations were performed to study the reaction between methyl peroxy radical (CH₃O₂) and O₂. The reaction proceeds through three different pathways (1) H-atom abstraction, (2) O₂ addition and (3) concerted H-atom shift and O₂ addition reactions. The concerted H-atom shift and O₂ addition pathway is the most favourable reaction both kinetically and thermodynamically. The major product channel formed from these reactions is H₂CO + OH + O₂. Trajectory calculations also confirm that H₂CO + OH + O₂ is the main product channel. An estimated rate constant expression for this reaction from master equation calculations is 4.20 × 10¹³ e^-8676/T cm³ mole^-1 s^-1.

Increased sanitization potency of hydrogen peroxide with synergistic O3 and intense pulsed light for non-woven polypropylene

Supplies of respiratory masks have recently become a concern due to the onset of the SARS-CoV-2 pandemic. Sanitization and reuse of masks can alleviate high mask consumption and production stresses. In the present work, improved sanitization potency of vaporous hydrogen peroxide (VHP) treatment of resilient bacterial spores while retaining polymeric filter performance was explored. A batch fumigation chamber with hydrogen peroxide (H₂O₂) vapor and ozone (O₃) is featured, followed by intense pulsed light (IPL) flash treatments. A resilient bacterial indicator, Geobacillus stearothermophilus (G. stearothermophilus), was utilized to compare the efficacy of various H₂O₂ concentrations in combination with O₃ and IPL. It was found that exposure to 30 minutes of 4.01 L min⁻¹ 0.03% H₂O₂ aqueous vapor and 3 g h⁻¹ O₃ followed by 10 IPL flashes per side completely inactivated G. stearothermophilus. The xenon sourced IPL irradiation was found to synergistically enhance radical production and strengthen the complementary biocidal interaction of H₂O₂ with O₃. Due to the synergistic effects, H₂O₂ was able to sanitize at a diluted concentration of 0.03% H₂O₂. The physical properties, such as surface potential, tensile strength, hydrophobicity, and filtration efficiency of >300 nm saline water aerosol of fibrous polypropylene (PP) sheets, were maintained. In addition, no residue of sanitizers was detected, thus confirming the biosafety and applicability of this method to disposable masks. Performance was benchmarked and compared with commercially available processes. The synergistic regime was found to achieve sterilization of G. stearothermophilus at drastically reduced H₂O₂ concentrations and in ambient conditions relative to commercial methods.

By introducing synergistic elements to the VHP processes, potent sanitization of polymeric filters is achieved at low H₂O₂ concentrations.

No-Touch Automated Room Disinfection after Autopsies of Exhumed Corpses

Autopsies of exhumed bodies pose a risk of infections with environmental bacteria or fungi, which may be life-threatening. Thus, it is important to use effective methods of disinfection in forensic pathology facilities. In this study, we investigated the effectiveness of no-touch automated disinfection (NTD) system after autopsies of exhumed bodies. Directly after 11 autopsies of exhumed bodies, we used an NTD system based on a peroxone vapor to disinfect the air and surfaces. We measured microbial burden in the air and on surfaces before and after NTD. The NTD system reduced the mean bacterial burden in the air from 171 colony forming units (CFU)/m³ to 3CFU/m³. The mean fungal burden in the air decreased from 221 CFU/m³ to 9CFU/m³. The mean all-surface microbial burden was 79 CFU/100 cm² after all autopsies, and it decreased to 2 CFU/100 cm² after NTD. In conclusion, the peroxone-based NTD system was effective for decontamination of the air and surfaces in a dissecting room after autopsies of exhumed bodies.

No-Touch Automated Disinfection System for Decontamination of Surfaces in Hospitals

Background: Hospital-acquired infections (HAIs) remain a common problem, which suggests that standard decontamination procedures are insufficient. Thus, new methods of decontamination are needed in hospitals. Methods: We assessed the effectiveness of a no-touch automated disinfection (NTD) system in the decontamination of 50 surfaces in 10 hospital rooms. Contamination of surfaces was assessed with a microbiological assay and an ATP bioluminescence assay. Unacceptable contamination was defined as > 100 colony forming units/100 cm² in the microbiological assay, and as ≥ 250 relative light units in the ATP assay. Results: When measured with the microbiological assay, 11 of 50 surfaces had unacceptable contamination before NTD, and none of the surfaces had unacceptable contamination after NTD (p < 0.001). On the ATP bioluminescence assay, NTD decreased the number of surfaces with unacceptable contamination from 28 to 13, but this effect was non-significant (p = 0.176). On the microbiological assay taken before NTD, the greatest contamination exceeded the acceptable level by more than 11-fold (lamp holder, 1150 CFU/100 cm²). On the ATP bioluminescence assay taken before NTD, the greatest contamination exceeded the acceptable level by more than 43-fold (Ambu bag, 10,874 RLU). Conclusion: NTD effectively reduced microbiological contamination in all hospital rooms. However, when measured with the ATP bioluminescence assay, the reduction of contamination was not significant.

First-principles-based reaction kinetics from reactive molecular dynamics simulations: Application to hydrogen peroxide decomposition

This paper presents our vision of how to use in silico approaches to extract the reaction mechanisms and kinetic parameters for complex condensed-phase chemical processes that underlie important technologies ranging from combustion to chemical vapor deposition. The goal is to provide an analytic description of the detailed evolution of a complex chemical system from reactants through various intermediates to products, so that one could optimize the efficiency of the reactive processes to produce the desired products and avoid unwanted side products. We could start with quantum mechanics (QM) to ensure an accurate description; however, to obtain useful kinetics we need to average over ∼10-nm spatial scales for ∼1 ns, which is prohibitively impractical with QM. Instead, we use the reactive force field (ReaxFF) trained to fit QM to carry out the reactive molecular dynamics (RMD). We focus here on showing that it is practical to extract from such RMD the reaction mechanisms and kinetics information needed to describe the reactions analytically. This analytic description can then be used to incorporate the correct reaction chemistry from the QM/ReaxFF atomistic description into larger-scale simulations of ∼10 nm to micrometers to millimeters to meters using analytic approaches of computational fluid dynamics and/or continuum chemical dynamics. In the paper we lay out the strategy to extract the mechanisms and rate parameters automatically without the necessity of knowing any details of the chemistry. We consider this to be a proof of concept. We refer to the process as RMD2Kin (reactive molecular dynamics to kinetics) for the general approach and as ReaxMD2Kin (ReaxFF molecular dynamics to kinetics) for QM-ReaxFF-based reaction kinetics.

An Evaluation of Gas Phase Enthalpies of Formation for Hydrogen-Oxygen (HxOy) Species

We have compiled gas phase enthalpies of formation for nine hydrogen-oxygen species (HxOy) and selected recommended values for H, O, OH, H2O, HO2, H2O2, O3, HO3, and H2O3. The compilation consists of values derived from experimental measurements, quantum chemical calculations, and prior evaluations. This work updates the recommended values in the NIST-JANAF (1985) and Gurvich et al. (1989) thermochemical tables for seven species. For two species, HO3 and H2O3 (important in atmospheric chemistry) and not found in prior thermochemical evaluations, we also provide supplementary data consisting of molecular geometries, vibrational frequencies, and torsional potentials which can be used to compute thermochemical functions. For all species, we also provide supplementary data consisting of zero point energies, vibrational frequencies, and ion reaction energetics.

Interconnection of reactive oxygen species chemistry across the interfaces of atmospheric, environmental, and biological processes

Oxidation reactions are ubiquitous and play key roles in the chemistry of the atmosphere, in water treatment processes, and in aerobic organisms. Ozone (O3), hydrogen peroxide (H2O2), hydrogen polyoxides (H2Ox, x > 2), associated hydroxyl and hydroperoxyl radicals (HOx = OH and HO2), and superoxide and ozonide anions (O2(-) and O3(-), respectively) are the primary oxidants in these systems. They are commonly classified as reactive oxygen species (ROS). Atmospheric chemistry is driven by a complex system of chain reactions of species, including nitrogen oxides, hydroxyl and hydroperoxide radicals, alkoxy and peroxy radicals, and ozone. HOx radicals contribute to keeping air clean, but in polluted areas, the ozone concentration increases and creates a negative impact on plants and animals. Indeed, ozone concentration is used to assess air quality worldwide. Clouds have a direct effect on the chemical composition of the atmosphere. On one hand, cloud droplets absorb many trace atmospheric gases, which can be scavenged by rain and fog. On the other hand, ionic species can form in this medium, which makes the chemistry of the atmosphere richer and more complex. Furthermore, recent studies have suggested that air-cloud interfaces might have a significant impact on the overall chemistry of the troposphere. Despite the large differences in molecular composition, concentration, and thermodynamic conditions among atmospheric, environmental, and biological systems, the underlying chemistry involving ROS has many similarities. In this Account, we examine ROS and discuss the chemical characteristics common to all of these systems. In water treatment, ROS are key components of an important subset of advanced oxidation processes. Ozonation, peroxone chemistry, and Fenton reactions play important roles in generating sufficient amounts of hydroxyl radicals to purify wastewater. Biochemical processes within living organisms also involve ROS. These species can come from pollutants in the environment, but they can also originate endogenously, initiated by electron reduction of molecular oxygen. These molecules have important biological signaling activities, but they cause oxidative stress when dysfunction within the antioxidant system occurs. Excess ROS in living organisms can lead to problems, such as protein oxidation-through either cleavage of the polypeptide chain or modification of amino acid side chains-and lipid oxidation.

Effectiveness of a novel ozone-based system for the rapid high-level disinfection of health care spaces and surfaces

BACKGROUND

Vapor-based fumigant systems for disinfection of health care surfaces and spaces is an evolving technology. A new system (AsepticSure) uses an ozone-based process to create a highly reactive oxidative vapor with broad and high-level antimicrobial properties.

METHODS

Ozone gas at 50-500 ppm was combined with 3% hydrogen peroxide vapor in a test chamber and upscaled in rooms measuring 82 m3 and 90 m3 in area. Test organisms included methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococcus, Escherichia coli, Pseudomonas aeruginosa, Clostridium difficile, and Bacillus subtilis spores dried onto steel discs or cotton gauze pads.

RESULTS

The combination of 80-ppm ozone with 1% hydrogen peroxide vapor achieved a very high level of disinfection, with a ≥6 log10 reduction in the bacteria and spores tested on steel discs and MRSA tested on cotton gauze during a 30- to 90-minute exposure. The entire system was scalable such that it achieved the same high level of disinfection in both the 81-m3 and 90-m3 rooms in 60-90 minutes.

CONCLUSION

The ozone hydrogen peroxide vapor system provides a very high level of disinfection of steel and gauze surfaces against health care-associated bacterial pathogens. The system is an advanced oxidative process providing a rapid and effective means of disinfecting health care surfaces and spaces.

Diels–Alder reaction of acenes with singlet and triplet oxygen – theoretical study of two-state reactivity

An interesting change in mechanism (from concerted to biradical) is described for the reaction of acenes (benzene through pentacene) with molecular oxygen (either singlet oxygen, 1Deltag-O2, or triplet oxygen, 3Sigmag-O2).

Platelet function unaffected by ozonated autohaemotherapy in chronically haemodialysed patients

BACKGROUND

The therapeutic use of ozone is still a controversial medical strategy due to the potential toxicity of ozone, which is recognized as a highly reactive oxidant. The reactive oxygen species are known to induce platelet aggregation, the process involved in the development of atherosclerosis and cardiovascular events. In the present study, the influence of ozonated autohaemotherapy (O3-AHT) on the platelet function was evaluated in chronically haemodialysed patients with peripheral arterial disease.

METHODS

This was an oxygen-controlled, cross-over study, in which nine sessions of autohaemotherapy with oxygen administration as a control were followed by nine sessions of O3-AHT. The platelet function was assessed by the extent of spontaneous aggregation (SPA) and agonist-induced aggregation (AIPA), where different concentrations of adenosine were used as an agonist.

RESULTS

There were no differences between SPA and AIPA assessed after nine sessions of O3-AHT and after nine sessions of autohaemotherapy with oxygen administration. SPA and AIPA did not change after the first session of O3-AHT as compared with the levels before this procedure.

CONCLUSION

O3-AHT with ozone concentration of 50 microg/ml and citrate as an anticoagulant does not induce platelet aggregation.

Hemiortho Esters and Hydrotrioxides as the Primary Products in the Low-Temperature Ozonation of Cyclic Acetals: An Experimental and Theoretical Investigation

Low-temperature ozonation (-78 degrees C) of 1,3-dioxolanes 1a-1f and 1,3-dioxanes 1g and h in acetone-d6, methyl acetate, and tert-butyl methyl ether produced both the corresponding hemiortho esters (2a-h, ROH) and acetal hydrotrioxides (3a-h, ROOOH) in molar ratios ROH/ROOOH ranging from 0.5 to 23. Both types of intermediates were fully characterized by 1H, 13C, and 17O NMR spectroscopy. DFT calculations suggest that ozone abstracts a hydride ion from 1 to form an ion pair, R+ -OOOH, which subsequently collapses to either the corresponding hemiortho ester (ROH) or the acetal hydrotrioxide (ROOOH). Hemiortho esters decomposed quantitatively into the corresponding hydroxy esters. Experimentally obtained activation parameters for the decomposition of 2a (E(a) = 13.5 +/- 1.0 kcal/mol, log A = 8.3 +/- 1.0) are in accord with a highly oriented transition state involving, according to B3LYP calculations (deltaH(a)(298) = 13.2 kcal/mol), two molecules of water as a bifunctional catalyst. This mechanism is also supported by the magnitude of the solvent isotope effect for the decomposition of 2e, i.e., k(H2O)/k(D2O) = 4.6 +/- 1.2. Besides the hydroxy esters and oxygen (3O2/1O2), dihydrogen trioxide (HOOOH) was formed in the decomposition of most of the acetal hydrotrioxides (ROOOH) investigated. The activation parameters for the decomposition of the hydrotrioxides 3a-e in various solvents were E(a) = 20 +/- 2 kcal/mol, log A = 13.5 +/- 1.5. Several mechanistic possibilities for the decomposition of ROOOH were tested by experiment and theory. The formation of the hydroxy esters and oxygen could be explained by the intramolecular transfer of the proton to form the hydroxy ester. The assistance of water in the decomposition of ROOOH to form the hydroxy esters, either directly or via hemiortho esters, was also investigated. According to DFT calculations, the formation of a hydroxy ester via hemiortho ester is energetically more favorable (deltaH(a)(298) = 14.5 kcal/mol), again due to the catalytic effect of two water molecules. HOOOH generation requires the involvement of water in the decomposition of ROOOH where the direct formation out of ROOOH is energetically preferred. The energy for a reaction between two molecules of water and singlet oxygen (delta1O2) is too high to occur in solution.

Oxygen, oxysterols, ouabain, and ozone: a cautionary tale

The recent account of the oxidation of tissue cholesterol by ozone created in human arterial plaques by the oxidation of water by electronically excited (singlet) dioxygen depends on the identification of the oxysterols formed and on the presumption that they are formed uniquely by ozone action. The chief oxysterols found, 3beta-hydroxy-5-oxo-5,6-secocholestan-6-al and 3beta,5-dihydroxy-5beta-B-norcholestane-6beta-carboxaldehyde, were identified as their 2,4-dinitrophenylhydrazones by chromatographic properties and a single mass spectral ion m/z 597 interpreted as [M-H](-). Conventional identification procedures for oxysterols were not conducted. Accordingly, absent other evidence, error may exist; such errors are known in the literature. Moreover, the assertion that ozone be the only oxidant that could form the 5,6-secosterol aldehyde from cholesterol is unproven. Other equally novel unproven processes can be posed. The account of biological ozone mimics prior 30-year-old reports of singlet oxygen itself in biological systems. Lest a similar history develop for biological ozone three topics of steroid oxidation are here reviewed to aid in understanding the current matter. Caution in evaluating the account of biological ozone is warranted.

endo/exo Isomerism in Norcarane and 2-Norcaranol Hydrotrioxides (ROOOH)

Ozonation of norcarane (1) yielded endo and exo norcarane hydrotrioxides (2a, 2b), as characterized by (1)H and (13)C NMR spectroscopy. Further ozonation of the primary decomposition products of these hydrotrioxides, i.e., 2-norcaranols (3), produced the corresponding isomeric 2-norcaranol hydrotrioxides (4a, 4b), and hydrogen trioxide (HOOOH).

The role of the HOOO(-) anion in the ozonation of alcohols: large differences in the gas-phase and in the solution-phase mechanism

The mechanism of the ozonation of isopropyl alcohol was investigated for the gas and the solution phase using second-order many body perturbation theory and density functional theory (DFT) with the hybrid functional B3LYP and a 6-311++G(3df,3pd) basis set. A careful analysis of calculated energies (considering thermochemical corrections, solvation energies, BSSE corrections, the self-interaction error of DFT, etc.) reveals that the gas-phase mechanism of the reaction is dominated by radical or biradical intermediates while the solution-phase mechanism is characterized by hydride transfer and the formation of an intermediate ion pair that includes the HOOO(-) anion. The product distribution observed for the ozonation in acetone solution can be explained on the basis of the properties of the HOOO(-) anion. General conclusions for the ozonation of alcohols and the toxicity of ozone (inhaled or administered into the blood) can be drawn.