HOCl Solution Research Articles

Superoxide-mediated Formation of Tyrosine Hydroperoxides and Methionine Sulfoxide in Peptides through Radical Addition and Intramolecular Oxygen Transfer

The chemistry underlying superoxide toxicity is not fully understood. A potential mechanism for superoxide-mediated injury involves addition to tyrosyl radicals, to give peptide or protein hydroperoxides. The rate constant for the reaction of tyrosyl radicals with superoxide is higher than for dimerization, but the efficiency of superoxide addition to peptides depends on the position of the Tyr residue. We have examined the requirements for superoxide addition and structurally characterized the products for a range of tyrosyl peptides exposed to a peroxidase/O(2)(.) system. These included enkephalins as examples of the numerous proteins and physiological peptides with N-terminal tyrosines. The importance of amino groups in promoting hydroperoxide formation and effect of methionine residues on the reaction were investigated. When tyrosine was N-terminal, the major products were hydroperoxides that had undergone cyclization through conjugate addition of the terminal amine. With non-N-terminal tyrosine, electron transfer from O(2)(.) to the peptide radical prevailed. Peptides containing methionine revealed a novel and efficient intramolecular oxygen transfer mechanism from an initial tyrosine hydroperoxide to give a dioxygenated derivative with one oxygen on the tyrosine and the other forming methionine sulfoxide. Exogenous amines promoted hydroperoxide formation on tyrosyl peptides lacking a terminal amine, without forming an adduct. These findings, plus the high hydroperoxide yields with N-terminal tyrosine, can be explained by a mechanism in which hydrogen bonding of O(2)(.) to the amine increases is oxidizing potential and alters its reactivity. If this amine effect occurred more generally, it could increase the biological reactivity of O(2)(.) and have major implications.

Theoretical investigation on the reaction of adhesion unit dopa in mussel with electrolyzing seawater

Adhesive proteins secreted by the marine mussel could bind strongly to all kinds of surfaces, for instance, ship hulls and petroleum pipelines. Studies indicated that there was an unusual amino acid 3,4-dihydroxy- l-phenylanine (dopa), which was the crucial super adhesive unit in the proteins. The technology of electrolyzing seawater was employed to generate HOCl solution to hinder the adhesion. However, the detailed anti-fouling mechanism of HOCl solution remained unknown to be fully explained. Herein, we theoretically reported a study of single molecular (dopa) reaction under the HOCl solution environment, which would be helpful to reveal the anti-fouling mechanism through electrolyzing seawater. By using the density functional theory (DFT) quantum mechanics procedure, we theoretically studied the reaction mechanism of the adhesive unit dopa in mussel with electrolyzing seawater. Two possible pathways (1 and 2) were obtained (Fig. 6). The transition state for each pathway was determined, the intrinsic reaction coordinate (IRC) was analyzed and the mechanism had been confirmed. The calculations indicated dopa tended to have electrophonic attacking substitution reaction to generate 3-chlorine-4,5-dihydroxyphenylalanine (dopa-Cl) with different pathways, which hindered the formulation of conjuncted dopa–dopa and thus the stickiness among mussel adhesive proteins reduced. The transition states computation showed that pathway (1) had one transition state (TS1-1) with an activation energy of 102.22 kJ mol −1, while pathway (2) had two transition states (TS2-1, TS2-2) with activation energies of 191.98 kJ mol −1 and 42.00 kJ mol −1 respectively and one intermediate (IM2-1). Rate constant value of pathway (1) was much bigger than that of pathway (2) regardless of high or low temperature, which meant that in the reaction process, pathway (1) was the favorable reaction step; but as the temperature rose, the competitiveness of pathway (2) gradually increased. After the theoretical calculation, we found that it was Cl + played an important and direct role in the dopa's modification.

Effects of a Low Concentration Hypochlorous Acid Nasal Irrigation Solution on Bacteria, Fungi, and Virus

Saline irrigation would be more effective for chronic sinusitis patients if it had bactericidal effects. Low concentrations of hypochlorous acid may be used as a nasal irrigation solution. First, we developed a 0.85% NaCl solution by adding NaCl to tap water (pH 7.0 and 8.4) and measuring the concentration of free chlorine and hypochlorous acid after giving the solution a short electrical impulse of 20 seconds. Then we investigated whether the derived hypochlorous acid had a toxic effect on human primary nasal epithelial cells, if and what effect it had on the expression of mucin genes, and, finally, if it had bactericidal, fungicidal, or virucidal effects. In vitro biochemical experiment. We treated human primary nasal epithelial cells with 3.5 ppm of hypochlorous acid and then examined the cells for cytotoxicity. We also investigated the bactericidal, fungicidal, and virucidal effects by challenging the cells with the following microorganisms Aspergillus fumigatus, Haemophilus influenzae, Klebsiella pneumoniae, Rhizopus oryzae, Candida albicans, Methicillin-resistant Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus pyogenes. To study the virucidal effects of HOCl, we used the human influenza A virus to challenge the cells. : In the cytotoxicity assay and in the morphological examination, the cells did not show anytoxicity at 30 minute or 2 hours after treatment with HOCl. More than 99% of bactericidal or fungicidal activity was noted for all species, except for Candida albicans, in tap water at either pH 7.0 or 8.4. In addition, a 3.2-log10 reduction was achieved in cells challenged with the human influenza A virus. A low concentration HOCl solution can be used as an effective nasal irrigation solution.

Evaluation of Liquid- and Fog-Based Application of Sterilox Hypochlorous Acid Solution for Surface Inactivation of Human Norovirus

Noroviruses (NVs) are the most frequent cause of outbreaks of gastroenteritis in common settings, with surface-mediated transfer via contact with fecally contaminated surfaces implicated in exposure. NVs are environmentally stable and persistent and have a low infectious dose. Several disinfectants have been evaluated for efficacy to control viruses on surfaces, but the toxicity and potential damage to treated materials limits their applicability. Sterilox hypochlorous acid (HOCl) solution (HAS) has shown broad-spectrum antimicrobial activity while being suitable for general use. The objectives of this study were to evaluate the efficacy of HAS to reduce NV both in aqueous suspensions and on inanimate carriers. HOCl was further tested as a fog to decontaminate large spaces. HOCl effectiveness was evaluated using nonculturable human NV measured by reverse transcriptase PCR (RT-PCR) and two surrogate viruses, coliphage MS2 and murine NV, that were detected by both infectivity and RT-PCR. Exposing virus-contaminated carriers of ceramic tile (porous) and stainless steel (nonporous) to 20 to 200 ppm of HOCl solution resulted in > or = 99.9% (> or = 3 log10) reductions of both infectivity and RNA titers of tested viruses within 10 min of exposure time. HOCl fogged in a confined space reduced the infectivity and RNA titers of NV, murine NV, and MS2 on these carriers by at least 99.9% (3 log10), regardless of carrier location and orientation. We conclude that HOCl solution as a liquid or fog is likely to be effective in disinfecting common settings to reduce NV exposures and thereby control virus spread via fomites.

Oxidative stress as a bio-marker of estrogen exposure in healthy veal calves

In humans, the use of estrogen-based contraceptives is positively related to oxidative stress, via the formation of 2-3,4-quinone metabolites as free radicals by an E2-4-hydroxylase. These compounds are directly genotoxic and can undergo redox cycling to form toxic reactive oxygen metabolites (ROMs). This prompted us to investigate oxidative stress in terms of ROMs and of the anti-oxidant power (AOP) in sera of veal calves exposed to 17β-estradiol (17βE). ROMs and AOP were measured by two colorimetric methods the former based on the Fenton reaction, the latter performed as a neutralization assay of a titred HOCl solution. 17βE Levels were screened by radio immuno assay (RIA) and confirmed by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS), and related for significance to the established threshold (40 ng l −1) in sera. Basal levels were measured in different groups of veal calves: mother suckling (MS; n=102), free grazing (FG; n=108), intensively farmed fed on soia and corn silage (IF−; n=104). In calves with 17βE above the threshold in sera (IF+; n=16), we recorded the highest ROMs level (3.15 mM H 2O 2), with a negative correlation with AOP values. IF+ data significantly differed even from those of MS calves (2.61 mM H 2O 2) naturally exposed to colostrum hormones. The absolute ROMs value combined with an impairment of the AOP adaptive response can be considered an epidemiological bio-marker for xenobiotic estrogen treatments.

EVALUATION OF A CALCIUM ALGINATE FILM FOR USE ON BEEF CUTS

ABSTRACTEffects of a calcium alginate coating on retail beef pieces and steaks were studied. Microbiological analyses were performed on beef pieces following treatments with: (1) a calcium alginate coating; (2) a 200 ppm HOCl solution; (3) a combination of 1 and 2; (4) a coliform inoculation and/or (5) no treatment (control). Each sample was wrapped in a polyvinyl chloride (PVC) film and stored at 5°C for up to 7 days. The rate of microbial growth for total and coliform counts on the meat was not significantly different with coated and uncoated meat samples. The HOCl treated meat had significantly lower total microbial counts and coliform populations when compared to either the calcium alginate or the HOCl‐calcium alginate treated meat. Acceptance of the calcium alginate film involved retail display and organoleptic evaluations of 40 2.54 cm thick beef steaks. Steaks that received the calcium alginate coating were significantly lower in shrinkage loss, drip and degree of off‐odor detected through 96 hr storage when compared to the uncoated steaks. The coating significantly prolonged muscle color through 96 hr storage. No significant differences were observed between treatments for appearance, surface discoloration, flavor, juiciness, tenderness, overall acceptability or cooking loss.