Hypochlorite Scavenging Research Articles

Exploring the Phytochemical Composition and the Bioactive Properties of Malbec and Torrontés Wine Pomaces from the Calchaquíes Valleys (Argentina) for Their Sustainable Exploitation.

Hydroalcoholic extracts from Malbec and Torrontés wine pomaces (Vitis vinifera L.) originating from the high-altitude vineyards of Argentina's Calchaquí Valleys were characterized. Total phenolics, hydroxycinnamic acids, orthodiphenols, anthocyanins, non-flavonoid phenolics, total flavonoids, flavones/flavonols, flavanones/dihydroflavonols, and tannins were quantified through spectrophotometric methods, with the Malbec extract exhibiting higher concentrations in most of phytochemical groups when compared to Torrontés. HPLC-DAD identified more than 30 phenolic compounds in both extracts. Malbec displayed superior antiradical activity (ABTS cation, nitric oxide, and superoxide anion radicals), reduction power (iron, copper, and phosphomolybdenum), hypochlorite scavenging, and iron chelating ability compared to Torrontés. The cytotoxicity assessments revealed that Torrontés affected the viability of HT29-MTX and Caco-2 colon cancer cells by 70% and 50%, respectively, at the highest tested concentration (1 mg/mL). At the same time, both extracts did not demonstrate acute toxicity in Artemia salina or in red blood cell assays at 500 µg/mL. Both extracts inhibited the lipoxygenase enzyme (IC50: 154.7 and 784.7 µg/mL for Malbec and Torrontés), with Malbec also reducing the tyrosinase activity (IC50: 89.9 µg/mL), and neither inhibited the xanthine oxidase. The substantial phenolic content and diverse biological activities in the Calchaquí Valleys' pomaces underline their potentialities to be valorized for pharmaceutical, cosmetic, and food industries.

Three-Dimensional Quantitative Structure and Activity Relationship of Flavones on Their Hypochlorite Scavenging Capacity.

Flavonoids, a class of polyphenolic substances widely present in the plant realm, are considered as ideal hypochlorite scavengers. However, to our knowledge, little study has focused on the structure-activity relationship between flavonoids and hypochlorite scavenging capacity. Herein, we report for the first time the three-dimensional quantitative structure and activity relationship (3D-QSAR) combined with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Four models derived from CoMFA and CoMSIA with different combinations of descriptors were built and compared; the CoMFA model, which included both steric and electrostatic fields, showed great potential (R2 = 0.989; Q2 = 0.818) in predictive quality according to both internal and external validation criteria. Additionally, the average local ionization energy (ALIE), electrostatic potential (ESP), and orbital weighted dual descriptor (OWDD) were determined to identify the key structural moiety for scavenging capacity of flavonoids against hypochlorite. The computational results indicated that hypochlorous acid (HClO) serves as an electrophile undergoing electrophilic addition to the C6 carbon, which has the highest negative charge density, which are influenced by the functional groups on the flavones. The DFT calculated mechanism revealed the catalytic role of water of mono- and di-chlorination reactions, characterized by low activation barriers, and the involvement of neutral, instead of high-energy carbocation, intermediates.

CD36 down regulation by the macrophage antioxidant 7,8-dihydroneopterin through modulation of PPAR-γ activity

CD36 is the key scavenger receptor driving the formation of cholesterol-loaded foam cells, the principal cellular component of atherosclerotic plaques. CD36 is down regulated by 7,8-dihydroneopterin, a potent superoxide and hypochlorite scavenging antioxidant generated by interferon-γ stimulated macrophages. 7,8-dihydroneopterin downregulates CD36 mRNA and protein levels so inhibiting macrophage foam cell formation in vitro. We examined the mechanism of 7,8-dihydroneopterin downregulation of CD36 by measuring CD36 and PPAR-γ levels by Western blot analysis, in the monocyte-like U937 cells with a range of PPAR-γ stimulants and inhibitors. Lipoxygenase activity was measured by monitoring linoleic acid oxidation at 234 nm for diene formation. Between 100 and 200 μM, 7,8-dihydroneopterin decreased CD36 levels by 50% within 12 h with levels dropping below 25% by 24 h. CD36 levels returned to basal levels after 24 h. Inhibition of protein synthesis by cycloheximide shows 7,8-dihydroneopterin had no effect on CD36 degradation rates. PPAR-γ levels were not altered by the addition of 7,8-dihydroneopterin. MAP Kinase, P38 and NF-κB pathways inhibitors SP600125, PD98059, SB202190 and BAY 11-7082, respectively, did not restore the CD36 levels in the presence of 7,8-dihydroneopterin. The addition of the lipophilic PPAR-γ activators rosiglitazone and azelaoyl-PAF prevented the CD36 downregulation by 7,8-dihydroneopterin. 7,8-dihydroneopterin inhibited soybean lipoxygenase and reduced U937 cell basal levels of cellular lipid oxides as measured by HPLC-TBARS analysis. The data show 7,8-dihydroneopterin down regulates CD36 expression by decreasing the level of lipid oxide stimulation of PPAR-γ promotor activity, potentially through lipoxygenase inhibition.

A smartphone-based portable analytical system for on-site quantification of hypochlorite and its scavenging capacity of antioxidants

A high-throughput smartphone-based colorimetric reader (HSCR) was developed to quantitatively detect hypochlorite in aqueous solution and determine hypochlorite scavenging capacity in high-throughput format by a blue probe DMMA-IR780, which changes from deep blue to pink upon epoxidation by hypochlorite on one of the double bonds. The reaction mechanism between probe and hypochlorite was study by mass spectrum and attribute to the formation and degradation of chlorohydrins. The color change was recorded by a smartphone-based colorimetric reader to apply into an android-based application for on-site determination and analysis. This portable system could quantify hypochlorite with linearity range of 0.43 to 875 μM and limit of detection at 0.08 μM. Taking advantages of smartphone and probe DMMA-IR780, the assay provides a cost-effective and hand-held platform for on-site HOCl determination and quantification of hypochlorite scavenging capacity of dietary antioxidants.

Two-Dimensional FTIR Spectroscopic Characterization of Functional Groups of NaOCl-Exposed Alginate: Insights into Membrane Refouling after Online Chemical Cleaning

In-depth understandings of the interactions between NaOCl and foulants (e.g., alginate) at a molecular level can provide a deeper insight into the optimization of chemical cleaning. In this study, two-dimensional Fourier transform infrared correlation spectroscopic (2D-FTIR-COS) analysis was used to probe the hypochlorite oxidation of alginate at normal wastewater treatment operating pH (i.e., 6, 7, and 8). The 2D-FTIR-COS characterization indicated that the groups in alginate were degraded by NaOCl in a similar sequence at all investigated pHs: carboxylate groups (-COOH at pH 6 and 7) > C-O-C bonds, C-O bonds of uronic acids > C-O-C bonds. The results also showed that the presence of hemiacetals, which are formed by uronic acids, can protect alginate chains from oxidation during their initial exposure to NaOCl (30 min) and thus maintain alginate at a constant molecular size. Additionally, the rupture of C-O-C bonds resulting from initial oxidation (30 min) increased the viscosity of alginate solution because of the decreased stiffness of alginate chains and the rise of stronger intermolecular junctions. Long-term exposure to NaOCl (480 min) largely degraded uronic acids and the C-O-C bonds of alginate molecules, leading to decreases in molecular weight and viscosity at pH 6 and 7. However, because of the low degree of oxidation at pH 8, molecular weight and viscosity of alginates were slightly changed after long-term exposure (480 min) to NaOCl. Our results imply that the partial oxidation of alginate during hypochlorite scavenging enhanced its fouling propensity, which could have a potential implication for the implementation of chemical cleaning.

Separation of chlorinated diastereomers of decarboxy-betacyanins in myeloperoxidase catalyzed chlorinated Beta vulgaris L. extract.

A comparative chromatographic evaluation of chlorinated decarboxylated betanins and betanidins generated under activity of hypochlorous acid exerted upon these highly antioxidative potent decarboxylated pigments derived from natural sources was performed by LC-DAD-ESI-MS/MS. Comparison of the chromatographic profiles of the chlorinated pigments revealed two different directions of retention changes in relation to the corresponding substrates. Chlorination of all betacyanins that are decarboxylated at carbon C-17 results in an increase of their retention times. In contrast, all other pigments (the non-decarboxylated betacyanins as well as 2-decarboxy- and 15-decarboxy-derivatives) exhibit lower retention after chlorination. During further chromatographic experiments based upon chemical transformation of the related pigments (decarboxylation and deglucosylation), the compounds' structures were confirmed. The elaborated method for determination of chlorinated pigments enabled analysis of a chlorinated red beet root extract that was submitted to the MPO/H2O2/Cl- system acting under inflammation-like conditions (pH 5). This indicates a promising possibility for measurement of these chlorinated pigments as indicators of specific inflammatory states wherein betacyanins and decarboxylated betacyanins act as hypochlorite scavengers.

Hypochlorite scavenging activity of cerium oxide nanoparticles

In this report, we provide evidence that specific synthesis of cerium oxide nanoparticles can scavenge the hypochlorite anion, which is a strong extracellular oxidant involved in the inflammatory processes.

Novel mechanism for scavenging of hypochlorite involving a periplasmic methionine-rich Peptide and methionine sulfoxide reductase.

ABSTRACTReactive chlorine species (RCS) defense mechanisms are important for bacterial fitness in diverse environments. In addition to the anthropogenic use of RCS in the form of bleach, these compounds are also produced naturally through photochemical reactions of natural organic matter and in vivo by the mammalian immune system in response to invading microorganisms. To gain insight into bacterial RCS defense mechanisms, we investigated Azospira suillum strain PS, which produces periplasmic RCS as an intermediate of perchlorate respiration. Our studies identified an RCS response involving an RCS stress-sensing sigma/anti-sigma factor system (SigF/NrsF), a soluble hypochlorite-scavenging methionine-rich periplasmic protein (MrpX), and a putative periplasmic methionine sulfoxide reductase (YedY1). We investigated the underlying mechanism by phenotypic characterization of appropriate gene deletions, chemogenomic profiling of barcoded transposon pools, transcriptome sequencing, and biochemical assessment of methionine oxidation. Our results demonstrated that SigF was specifically activated by RCS and initiated the transcription of a small regulon centering around yedY1 and mrpX. A yedY1 paralog (yedY2) was found to have a similar fitness to yedY1 despite not being regulated by SigF. Markerless deletions of yedY2 confirmed its synergy with the SigF regulon. MrpX was strongly induced and rapidly oxidized by RCS, especially hypochlorite. Our results suggest a mechanism involving hypochlorite scavenging by sacrificial oxidation of the MrpX in the periplasm. Reduced MrpX is regenerated by the YedY methionine sulfoxide reductase activity. The phylogenomic distribution of this system revealed conservation in several Proteobacteria of clinical importance, including uropathogenic Escherichia coli and Brucella spp., implying a putative role in immune response evasion in vivo.

Development of a Differential Pulse Voltammetric (DPV) Assay for Assessing the Hypochlorite Scavenging Capacity of Pure Compounds and Beverages

Hypochlorite has cytotoxic effect and can provoke the development of a number of chronic inflammatory diseases. A new assay for the assessment of hypochlorite scavenging capacity (HSC), based on the differential pulse voltammetric (DPV) analysis of hypochlorite before and after reduction by dietary antioxidants, was developed. This electroanalytical assay was validated by testing linearity, precision, and accuracy. The calibration curves of antioxidant compounds covering polyphenols, ascorbic acid, and glutathione were investigated, and their response sensitivities and linear concentration ranges were determined. The calibration graph of Trolox (reference compound) was linear with a slope of 6.82 × 10−3 A L mol−1. The limit of detection and limit of quantification for Trolox were 2.55 and 8.50 μM, respectively. Moreover, this method was successfully applied to evaluate the HSC of fruit juices with turbid and colored components. In comparison of popular probe-based methods and hypochlorite scavenging efficacy assay, the proposed DPV method is rapid and better represents the direct scavenging activity of antioxidant samples toward hypochlorite (i.e., the total amount of hypochlorite scavenged by antioxidants). Finally, the chemical meaning of HSC value based on multiple oxidation process (MOS) was analyzed by structural theoretical calculation. It was demonstrated that the proposed DPV-based method is applicable in reflecting the MOS of antioxidants. Overall, the recommended DPV method is simple and enables the direct evaluation of the total hypochlorite scavenging capacity of dietary antioxidants.

Optimization of dicarboxylic acid cellulose synthesis: Reaction stoichiometry and role of hypochlorite scavengers

The reaction conditions in terms of reaction time, sodium chlorite stoichiometry, and the effect of hypochlorite scavengers on the chlorite oxidation of dialdehyde cellulose (DAC) was studied. The impact of storage on the reactivity of DAC fibers was also investigated. It was found that chlorite oxidation of DAC is a rapid reaction, resulting in oxidation of 71% of the aldehyde after only 8min when 2.5 times excess of sodium chlorite compared to aldehyde groups was used. Reactivity of DAC was observed to decrease quickly during the storage and only 68% of the aldehyde groups reacted after two weeks storage compared to the reaction performed with freshly prepared DAC. Hydrogen peroxide and sulfamic acid were observed to increase the reaction efficiency of chlorite oxidation by reducing the amount of side-reactions between chlorite and hypochlorite. A minor amount of sulfamic acid can be used to replace acetic acid as a catalyst.

Dietary organosulfur compounds from garlic and cruciferous vegetables as potent hypochlorite scavengers

Dietary organosulfur compounds commonly found in garlic and cruciferous vegetables are potent hypochlorite scavengers as measured using a novel fluorescence assay based on quantum dots (QDs) as the nanoprobe. By using hydrogen sulfide as a standard, we quantified the HClO scavenging capacity of organosulfides in the following order: cysteine > methionine > phenethylisothiocyanate > diallyldisulfide ~ dially trisulfide. The reaction products of these sulfides with hypochlorite were characterized by LC–MS spectra, which revealed that the sulfur atoms are the acceptor of oxygen from hypochlorite. Finally, the hypochlorite scavenging activity of garlic upon heat treatment reduced the ClO− scavenging activity significantly.

Protection of flavonoids against hypochlorite-induced protein modifications

Plant polyphenols, such as flavonoids, are ubiquitous components of human diet, and have been recognised as efficient radical scavengers and antioxidants. Their protective effects were especially seen in cell-free assays. Whilst in living cells, depending on experimental conditions, polyphenols may manifest both anti- and pro-oxidative activity. In the present study, the effectiveness of fifteen structurally different flavonoids against hypochlorite-mediated changes in in vitro systems, with and without cells, was tested and compared. Quercetin was found to be the best protector against hypochlorite-mediated fluorescein bleaching and BSA thiol groups oxidation, whilst in living cells its effects on hypochlorite-associated cytotoxicity were moderate. Contrary, epigallocatechin gallate, pelargonidin and catechin, with less impressive hypochlorite scavenging activity in cell-free assays, were the most effective against 3-chlorotyrosine formation after hypochlorite treatment. Taken together, special care should be taken when extrapolating the results on antioxidant propensity of food bioactive compounds in vitro to the cellular milieu.

Hypochlorite scavenging activity of flavonoids.

Scavengers of hypochlorite, a highly reactive oxidant produced by activated phagocytes, could have potential therapeutic effects in diseases in which this oxidant plays a pathogenic role. Flavonoids are polyphenolic substances present in food plants and have been extensively studied for their antioxidant properties against various free radicals. Less is known about their reactivity with hypochlorite. In this study, the hypochlorite scavenging activity of flavonoids was investigated using a microplate assay recently developed in our laboratory. This method evaluates the ability of a substance to inhibit the formation of chloramines in human serum albumin upon oxidation by hypochlorite. Thirteen flavonoids were tested. Most of them inhibited human serum albumin oxidation at micro-molar concentrations and appeared more active than Trolox, a water-soluble equivalent of vitamin E. It was observed that the greater the number of hydroxyl substitutions, the greater the scavenging activity. The 3-hydroxy substitution seemed to be particularly important for scavenging activity, whereas the presence of a 2,3-double bond in the C ring did not. Flavonoids were found to be good hypochlorite scavengers in-vitro and further information is provided about the chemical aspects important for scavenging activity. Thus, flavonoids could have beneficial effects in diseases such as atherosclerosis in which hypochlorite plays a pathogenic role.

Hypochlorite scavenging activity of hydroxycinnamic acids evaluated by a rapid microplate method based on the measurement of chloramines.

Scavengers of hypochlorite (XOCl) could have beneficial effects in diseases in which this oxidant plays a pathogenic role. It has been reported that ferulic acid and chlorogenic acid, the quinic ester of caffeic acid, are good hypochlorite scavengers, but a systematic evaluation of the naturally occurring hydroxycinnamic acids (HCAs), which these substances belong to, has not been performed yet. Thus, in this work we studied, by two different in-vitro methods, the antioxidant activity of five HCAs: p-coumaric acid, ferulic acid, sinapinic acid, caffeic acid and chlorogenic acid. The methods applied in this study were based on the oxidation of human serum albumin (HSA) by XOCl, a new microplate method based on the measurement of chloramines and a previously described carbonyl assay. Firstly, lysine-derived chloramines, in the presence or absence of the HCAs, were detected using 5-thio-2-nitrobenzoic acid (TNB), measuring the absorbance at 415 nm by a microplate reader. To remove excess XOCl, Trolox, a known XOCl scavenger, was added before TNB. Secondly, lysine-derived carbonyls, in the presence or absence of the HCAs, were detected by using 2,4-dinitrophenylhydrazine. Hydroxycinnamic acids appeared active (caffeic >/= sinapinic > chlorogenic congruent with ferulic > p-coumaric acid) by both methods, suggesting possible pharmacological applications for these compounds, which are present at high concentrations in the plant kingdom.

Influence of ceruloplasmin and lactoferrin on the chlorination activity of leukocyte myeloperoxidase assayed by chemiluminescence

We demonstrate that addition of H2O2 to a mixture of myeloperoxidase (MPO), chloride and luminol immediately evokes a short intense flash of chemiluminescence (CL). This flash is diminished in the absence of MPO or chloride, and in the complete system it is suppressed by an MPO inhibitor azide, hypochlorite scavengers taurine or methionine, or an MPO peroxidase-cycle substrate guaiacol. Hence, this CL is mostly due to the MPO halogenation function; a measure of this activity is provided by the integral CL. With three independent methods (CL, taurine chlorination, and peroxidase assay) it is shown that MPO activity is suppressed by ceruloplasmin (Cp). Lactoferrin has no effect either on MPO or on the MPO-Cp complex. It is also shown that peroxidase inhibition by Cp is the stronger the larger is the MPO substrate, which suggests steric hindrances to substrate binding in the MPO-Cp complex. Importantly, the conventional chlorination and peroxidase assays detect MPO inhibition by Cp only at a large excess of the latter, whereas the CL assay reveals it at stoichiometric ratios characteristic of the naturally occurring protein complexes.

Antioxidant Evaluation of Three Adaptogen Extracts

Adaptogens are harmless herbs which have pharmaceutical benefits due to their balancing, regulative and tonic functions. However, despite these medicinal effects, the antioxidant potential of adaptogens is rarely mentioned. This study investigated the antioxidant potential of 3 adaptogen extracts, Rhodiola rosea (golden root), Eleutherococcus senticosis (Siberian ginseng) and Emblica officinalis (Indian gooseberry, Amla). The results of this study showed that R. rosea had the highest potential for singlet oxygen scavenging, hydrogen peroxide scavenging, ferric reducing, ferrous chelating and protein thiol protection than either of the other 2 extracts. E. senticosis, on the other hand, showed the best potential for hypochlorite scavenging. In addition, the polyphenol content in the 3 adaptogen extracts followed the order: R. rosea, E. officinalis and E. senticosis. Our data suggest that the antioxidant potential of the 3 adaptogen extracts was proportional to their respective polyphenol content. The supplementation of adaptogen extracts containing high levels of polyphenols may not only have adaptogen properties, but may decrease the risk of complications induced by oxidative stress.

Hydrogen sulphide: A novel physiological inhibitor of LDL atherogenic modification by HOCl

Hypochlorite (HOCl), the product of the activated myeloperoxidase/H2O2/chloride (MPO/H2O2/Cl− ) system is favored as a trigger of LDL modifications, which may play a pivotal role in early atherogenesis. As HOCl has been shown to react with thiol-containing compounds like glutathione and N-acetylcysteine protecting LDL from HOCl modification, we have tested the ability of hydrogen sulfide (H2S)—which has recently been identified as an endogenous vasorelaxant—to counteract the action of HOCl on LDL. The results show that H2S could inhibit the atherogenic modification of LDL induced by HOCl, as measured by apolipoprotein alterations. Beside its HOCl scavenging potential, H2S was found to inhibit MPO (one may speculate that this occurs via H2S/heme interaction) and destroy H2O2. Thus, H2S may interfere with the reactants and reaction products of the activated MPO/H2O2/Cl− system. Our data add to the evidence of an anti-atherosclerotic action of this gasotransmitter taking the role of HOCl in the atherogenic modification of LDL into account.

Phenolics as potential antioxidant therapeutic agents: Mechanism and actions

Accumulating chemical, biochemical, clinical and epidemiological evidence supports the chemoprotective effects of phenolic antioxidants against oxidative stress-mediated disorders. The pharmacological actions of phenolic antioxidants stem mainly from their free radical scavenging and metal chelating properties as well as their effects on cell signaling pathways and on gene expression. The antioxidant capacities of phenolic compounds that are widely distributed in plant-based diets were assessed by the Trolox equivalent antioxidant capacity (TEAC), the ferric reducing antioxidant power (FRAP), the hypochlorite scavenging capacity, the deoxyribose method and the copper-phenanthroline-dependent DNA oxidation assays. Based on the TEAC, FRAP and hypochlorite scavenging data, the observed activity order was: procyanidin dimer > flavanol > flavonol > hydroxycinnamic acids > simple phenolic acids. Among the flavonol aglycones, the antioxidant propensities decrease in the order quercetin, myricetin and kaempferol. Gallic acid and rosmarinic acid were the most potent antioxidants among the simple phenolic and hydroxycinnamic acids, respectively. Ferulic acid displayed the highest inhibitory activity against deoxyribose degradation but no structure–activity relationship could be established for the activities of the phenolic compounds in the deoxyribose assay. The efficacies of the phenolic compounds differ depending on the mechanism of antioxidant action in the respective assay used, with procyanidin dimers and flavan-3-ols showing very potent activities in most of the systems tested. Compared to the physiologically active (glutathione, α-tocopherol, ergothioneine) and synthetic (Trolox, BHA, BHT) antioxidants, these compounds exhibited much higher efficacy. Plant-derived phenolics represents good sources of natural antioxidants, however, further investigation on the molecular mechanism of action of these phytochemicals is crucial to the evaluation of their potential as prophylactic agents.

Interaction of exogenous hypochlorite or hypochlorite produced by myeloperoxidase + H2O2 + Cl- system with unsaturated phosphatidylcholines.

The interaction between unsaturated phosphatidylcholines and either exogenous or endogenous (produced by the enzyme system involving myeloperoxidase (MPO), H2O2, and Cl-) hypochlorite was studied in multilayer liposomes containing oleic, linoleic, and arachidonic acid residues using MALDI-TOF mass spectrometry. At pH 7.4, hypochlorite reacts with the double bond of the oleic acid residue in 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine producing oleic acid chlorohydrin as the main product. Minor amounts of glycols and epoxides were also detected. The main products of the reaction of hypochlorite with 1-stearoyl-2-linoleyl-sn-glycero-3-phosphocholine were mono- and di-chlorohydrins of linoleic acid. The signals of monoglycol, epoxide, and glycol- or epoxide-containing monochlorohydrin derivatives were also present in the mass spectrum. The main products of the reaction of hypochlorite with 1-stearoyl-2-arachidonyl-sn-glycero-3-phosphocholine were lysophosphatidylcholine (1-stearoyl-sn-glycero-3-phosphocholine) and mono-, di-, and trichlorohydrin. Monoglycol and its derivatives containing one or two chlorohydrin groups were also detected. Along with those, carbonyl compounds (aldehyde and acid) formed as a result of double bond breakage in fifth position of arachidonate were detected. Monochlorohydrin was also found when liposomes comprising 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine were incubated in the presence of enzymatic mixture, MPO + H2O2 + Cl-, at pH 6.0. In the absence of the enzyme or either of its substrates (H2O2 or Cl-) or in the presence of the MPO inhibitor (sodium azide) or hypochlorite scavengers (taurine or methionine), monochlorohydrin formation was not observed. These data confirm the suggestion that just the hypochlorite generated in MPO-catalysis provides for chlorohydrin formation. Thus, the use of MALDI-TOF mass spectrometry has shown, along with chlorohydrins, glycols and epoxides as the products of hypochlorite interaction with unsaturated phosphatidylcholines at physiological pH. It was first determined that hypochlorite breaks double bonds in polyunsaturated phosphatidylcholine and also causes lysophosphatidylcholine formation.

Efficacy of Hypochlorous Acid Scavengers in the Prevention of Protein Carbonyl Formation

We observed that protein (bovine serum albumin) carbonyl content increases upon hypochlorite oxidation, and this increase is inhibited in a concentration-dependent manner in the presence of hypochlorite scavengers. Based on this observation, we tested whether some known hypochlorite scavengers (lipoic acid, cysteine, and glutathione) and some other antioxidants (uric acid, ascorbic acid, α-tocopherol, and probucol) could prevent protein carbonyl formation.N-acetylcysteine, dihydrolipoic acid, cysteine, and glutathione (reduced form, GSH), which otherwise could not be tested in a previously reported 5-thio-2-nitrobenzoic acid test system, were successfully evaluated in our assay. The hypochlorite scavenging capacity of different compounds, compared by determining the IC50(concentration which produces 50% inhibition), showed that the compounds tested have the following potency: dihydrolipoic acid > GSH,N-acetylcysteine > cysteine >S-methyl glutathione > lipoic acid, ascorbic acid > cystine, GSSG, and uric acid. No scavenging ability was observed for either α-tocopherol or probucol.