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COMBINATION OF SIX COMPOUNDS SYNERGISTICALLY BOOSTS ANTIOXIDANT EFFECTS EX VIVO

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Free radicals are a normal component of cellular oxygen metabolism in mammals. However, free radical-associated damage is an important factor in many pathological processes. Glycation and oxidative damage cause protein modifications, frequently observed in numerous diseases. Albumin represents a very abundant and important circulating antioxidant. This review brings together recent insights on albumin antioxidant properties. First, it focuses on the different activities of albumin concerning protein antioxidation. In particular, we describe the role of albumin in ligand binding and free radical-trapping activities. In addition, physiological and pathological situations that modify the antioxidant properties of albumin are reported.
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Introduction An imbalance between oxidants and antioxidants in favour of oxidants, potentially leading to damage, is termed oxidative stress. Antioxidants (AO), either enzymatic or non-enzymatic, are the ones that can reduce diverse effects of pro-oxidants such as DNA, proteins and lipids damage. Chalcones (1,3-diaryl-2-propen-1-ones) are open chain flavonoids that are widely biosynthesized in plants. Aim of this study was to test antioxidative potency of 15 chalcones (Chs) in in vitro model in serum (native conditions), so as with exogenously induced oxidative stress. Material and methods Oxidative stress was induced in serum samples of healthy individuals with 0.25 mmol/L terc-buthyl-hydroperoxide (TBH), and then we monitored the effects of various concentrations of chalcones on oxidative stress parameters: total antioxidative status (TAS), total oxidative status (TOS), total concentration of sulfhydryl group (SHG) and prooxidative-antioxidative balance (PAB), and calculated prooxidative score, antioxidative score, and oxy score (OS). Nonparametric repeated measures ANOVA (Friedman's test) was used for comparison of antioxidative potency of samples with 15 different chalcones, in a native state and upon TBH influence. Spearman's nonparametric correlation analysis was used for estimation of relation between different parameters. Results Negative Oxy Score (OS) values for Chs11-15 showed significantly stronger antioxidative potency compared to other investigated chalcones (p < 0.05). Ch11, Ch13 and Ch14 remained with negative OS even after TBH addition, whereas OS of Ch12 and Ch15 became positive, with small nominal values. Samples with Ch11 and Ch13 showed significant negative correlation between TAS and TOS (p < 0.05 for both), but in Ch14 sample the negative correlation existed between TAS and PAB (p < 0.05). Conclusion Lower value of OS (i.e. better antioxidative potency) was noticed in samples with Ch11-Ch15. Electron-donor effects of substituent groups as a structural part of these chalcones could explain its antioxidative capability. Phenolic and methyl groups are responsible for antioxidative ability enhancement of five chalcones with the best activity.
Article
A direct and an indirect relationship between paraoxonase 1 (PON1) and atherosclerosis exists. Given PON1's physical location within high‐density lipoprotein (HDL) particles and its recognized enzyme activity, it is certainly reasonable to suggest that PON1 facilitates the antiatherogenic nature of HDL particles. PON1 also plays a role in regulating reverse cholesterol transport, antioxidative, anti‐inflammatory, antiapoptotic, vasodilative, and antithrombotic activities and several endothelial cell functions. HDL dysfunctionality is a more recent issue and seems to be centered on pathological conditions affecting HDL structure and size profiles. This review is focused on the role of PON1 status in different atherosclerosis‐related diseases that we have studied over the last twenty years (coronary heart disease, acute ischemic stroke, diabetes mellitus type 2, end‐stage renal disease, chronic obstructive pulmonary disease, and sarcoidosis) with the aim to determine the true value of PON1 as a biomarker. The role of PON1 in cancer is also covered, as risk factors and mechanisms underlying both atherosclerosis and cancer share common features.
Article
The connection of oxidative stress with dyslipidemia creates a newly-emerging atherosclerosis risk factor involved in acute ischemic stroke development. This study analyzed the influence of oxidative stress on structural changes of high-density lipoprotein (HDL) particles connected with modification in protective paraoxonase 1 (PON1) activity. This study used 185 patients with acute ischemic stroke and 185 apparently healthy controls. Oxidative stress status, PON1 status, lipids and high-sensitivity C-reactive protein (hsCRP) were determined. In isolated HDL lipoprotein fraction we determined selected markers of oxidative stress (malondialdehyde, MDA) and the content of total sulfhydryl (SH) groups. The capability of oxidative and PON1 status parameters to discriminate patients according to survival status was evaluated. Stroke patients had lower HDL-cholesterol than controls and a remarkable fall in PON1 activity (control group-227U/L, survivors-42U/L, lethal outcome group-61U/L, p < 0.001), along with more prominent inflammation. Pronounced oxidative stress and impaired antioxidative protection was present among patients. HDL fraction analysis revealed a significant decrease of SH groups content (control group vs. patients, p < 0.05) and increased in MDA content in patients (lethal outcome vs. control group, p < 0.05). According to logistic regression analysis, the best predictor of disease outcome was oxidative stress marker - prooxidative-antioxidative balance (PAB). Pronounced oxidative stress in this group of acute ischemic stroke patients probably led to HDL structural changes, which could further cause an alteration or decrease of PON1 activity. Evidence of increased prooxidant level associated with decreased protective, antioxidative factors suggests their mutual involvement in this complex pathology. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Article
The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with (67)Zn and (70)Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6-71.0) and was not different from that from zinc gluconate with 60.9% (50.6-to 71.7). Absorption from zinc oxide at 49.9% (40.9-57.7) was significantly lower than from both other supplements (P < 0.01). Three participants had little or no absorption from zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at clinicaltrials.gov as NCT01576627.
Article
The superoxide dismutase which is present in the cytosol of eukaryotic cells is a cuprozinc enzyme (SODCu2Zn2)(E.C. 1. 15. 1. 1). It catalyses the dismutation of superoxide anions O2 to hydrogen peroxide (H2O2) plus oxygen. the importance of copper for the activity of the enzyme is well established and this activity can be used as a marker of copper status. Zinc is also essential for many enzymatic activities: however, the link between zinc nutritional status and SOD activity remains poorly explored. the aim of the present work was to discover whether there is a relationship in vivo between catalytic activity of superoxide dismutase and nutritional status of zinc. Three ap proaches have been used; the eflect of increasing concentrations of zinc on the in vitro activity of different forms of the enzyme: native SOD, zinc-depleted (SODCu2E2)and zinc- and copper-depleted apoenzyme (SODE2E2)The importance of zinc on SOD activity in vivo was also studied by determining the SOD activity in zinc-deficient rats, and in dialysis patients in whom it is known that the trace element status is highly disturbed. Our data confirm that zinc modulates superoxide dismutase activity in vitro, since the addition of zinc to SODCu2E2led a significant increase in catalytic activity. Moreover, in vivo SOD activity in zinc-deficient rats was decreased compared with control, and chronic renal patients, showed a concommitant decrease in SOD activity which paralleled their zinc levels.
Article
The term "antioxidant paradox" is often used to refer to the observation that oxygen radicals and other "reactive oxygen species" are involved in several human diseases, but giving large doses of dietary antioxidant supplements to human subjects has, in most studies, demonstrated little or no preventative or therapeutic effect. Why should this be? First, the role of reactive oxygen species in the origin and/or progression of most human diseases is unclear, although they probably are important in cancer, neurodegenerative diseases, and perhaps some others. Second, the endogenous antioxidant defences in the human body are complex, interlocking and carefully regulated. The body's "total antioxidant capacity" seems unresponsive to high doses of dietary antioxidants so that the amount of oxidative damage to key biomolecules is rarely changed. Indeed, manipulation of endogenous antioxidant levels (e.g. by supplying weak "pro-oxidants") may be a more useful approach to treatment and prevention of diseases in which reactive oxygen species are important than is consumption of large doses of "dietary antioxidants". © 2012 The Authors. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.
Article
Reactive oxygen species, such as superoxide and hydrogen peroxide, are generated in all cells by mitochondrial and enzymatic sources. Left unchecked, these reactive species can cause oxidative damage to DNA, proteins, and membrane lipids. Glutathione peroxidase-1 (GPx-1) is an intracellular antioxidant enzyme that enzymatically reduces hydrogen peroxide to water to limit its harmful effects. Certain reactive oxygen species, such as hydrogen peroxide, are also essential for growth factor-mediated signal transduction, mitochondrial function, and maintenance of normal thiol redox-balance. Thus, by limiting hydrogen peroxide accumulation, GPx-1 also modulates these processes. This review explores the molecular mechanisms involved in regulating the expression and function of GPx-1, with an emphasis on the role of GPx-1 in modulating cellular oxidant stress and redox-mediated responses. As a selenocysteine-containing enzyme, GPx-1 expression is subject to unique forms of regulation involving the trace mineral selenium and selenocysteine incorporation during translation. In addition, GPx-1 has been implicated in the development and prevention of many common and complex diseases, including cancer and cardiovascular disease. This review discusses the role of GPx-1 in these diseases and speculates on potential future therapies to harness the beneficial effects of this ubiquitous antioxidant enzyme.
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Vertebrates sequester iron from invading pathogens, and conversely, pathogens express a variety of factors to steal iron from the host. Recent work has demonstrated that in addition to iron, vertebrates sequester zinc and manganese both intracellularly and extracellularly to protect against infection. Intracellularly, vertebrates utilize the ZIP/ZnT families of transporters to manipulate zinc levels, as well as Nramp1 to manipulate manganese levels. Extracellularly, the S100 protein calprotectin sequesters manganese and potentially zinc to inhibit microbial growth. To circumvent these defenses, bacteria possess high affinity transporters to import specific nutrient metals. Limiting the availability of zinc and manganese as a mechanism to defend against infection expands the spectrum of nutritional immunity and further establishes metal sequestration as a key defense against microbial invaders.
Article
Plasma from fasted adult male subjects was labeled in vitro with 54MnCl2 and then fractionated using several techniques. Molecular sieve chromatography showed that the major 54Mn-containing peak had a very low molecular weight (VLMW), although four other significant peaks, one of which corresponded to the mass of transferrin (Tf), were also observed. The 54Mn content of the Tf peak increased with increasing incubation time in vitro, suggesting the oxidation of Mn+2 to Mn+3 before its association with Tf. This time-dependent effect was verified using affinity chromatography consisting of immobilized anti-Tf. Electrophoretic analyses of plasma yielded equivocal results, indicating a limited value of this method for investigating plasma manganese localization. The above findings are discussed in the context of factors that influence the oxidation and metabolism of Mn2+ in human plasma.
Article
For 8 wk 5 groups of 10 men each were given 0.5 g/day DL-methionine, 150 micrograms Se/day as sodium selenite with or without methionine or 150 micrograms Se/day as selenomethionine with or without methionine. Twenty subjects received placebo as controls. Initially plasma Se rose more rapidly than RBC Se. Increases in Se levels were significantly greater with selenomethionine than with the selenite supplement. In the placebo and methionine supplemented groups neither plasma nor RBC Se varied significantly over the course of the study. Supplementation with selenium resulted in marked increases in plasma and RBC GSH-Px within 2 and 4 wk, respectively. Plasma and RBC GSH-Px activity did not differ significantly between Se-supplemented groups. These studies suggest that selenomethionine-Se was more effective in raising plasma and RBC Se than was selenite-Se. Methionine supplements may increase the bioavailability of selenium in severely deficient subjects.
Article
Selenium has been increasingly recognized as an essential element in biology and medicine. Its biochemistry resembles that of sulfur, yet differs from it by virtue of both redox potentials and stabilities of its oxidation states. Selenium can substitute for the more ubiquitous sulfur of cysteine and as such plays an important role in more than a dozen selenoproteins. We have chosen to examine zinc-sulfur centers as possible targets of selenium redox biochemistry. Selenium compounds release zinc from zinc/thiolate-coordination environments, thereby affecting the cellular thiol redox state and the distribution of zinc and likely of other metal ions. Aromatic selenium compounds are excellent spectroscopic probes of the otherwise relatively unstable functional selenium groups. Zinc-coordinated thiolates, e.g., metallothionein (MT), and uncoordinated thiolates, e.g., glutathione, react with benzeneseleninic acid (oxidation state +2), benzeneselenenyl chloride (oxidation state 0) and selenocystamine (oxidation state -1). Benzeneseleninic acid and benzeneselenenyl chloride react very rapidly with MT and titrate substoichiometrically and with a 1:1 stoichiometry, respectively. Selenium compounds also catalyze the release of zinc from MT in peroxidation and thiol/disulfide-interchange reactions. The selenoenzyme glutathione peroxidase catalytically oxidizes MT and releases zinc in the presence of t-butyl hydroperoxide, suggesting that this type of redox chemistry may be employed in biology for the control of metal metabolism. Moreover, selenium compounds are likely targets for zinc/thiolate coordination centers in vivo, because the reactions are only partially suppressed by excess glutathione. This specificity and the potential to undergo catalytic reactions at low concentrations suggests that zinc release is a significant aspect of the therapeutic antioxidant actions of selenium compounds in antiinflammatory and anticarcinogenic agents.
Article
Previous studies from this laboratory as well as others have demonstrated that breast tumor cells fail to undergo primary apoptosis in response to agents which induce DNA damage such as ionizing radiation and the topoisomerase II inhibitor adriamycin. Similarly, the primary response of breast tumor cells to vitamin D(3) [1,25-(OH)(2)-D(3)] and its analogs such as EB 1089 is growth inhibition, with apoptosis occurring in only a small fraction of the cell population. The possibility that the combination of vitamin D(3) compounds with radiation might promote cell death (i.e. through a differentiation stimulus plus DNA damage) was investigated by exposing both TP53 (formerly known as p53) wild-type and TP53 mutated breast tumor cells to 1,25-(OH)(2)-D(3) or EB 1089 for 48 h prior to irradiation. This combination resulted in enhanced antiproliferative effects in the TP53 wild-type MCF-7 cells based on both a clonogenic assay and the determination of numbers of viable cells. The combination of EB 1089 with radiation increased DNA fragmentation based on both the terminal transferase end-labeling (TUNEL) and bisbenzamide spectrofluorometric assays, suggesting the promotion of apoptosis. The observed increase in DNA fragmentation was not due to an enhancement of the extent of initial DNA damage induced by radiation. These findings suggest that vitamin D compounds may be useful in combination with radiation in the treatment of breast cancer.
Article
Blood vessels express 3 isoforms of superoxide dismutase (SOD): cytosolic or copper-zinc SOD (CuZn-SOD), manganese SOD (Mn-SOD) localized in mitochondria, and an extracellular form of CuZn-SOD (EC-SOD). Because there are no selective pharmacological inhibitors of individual SOD isoforms, the functional importance of the different SODs has been difficult to define. Recent molecular approaches, primarily the use of genetically-altered mice and viral-mediated gene transfer, have allowed investigators to begin to define the role of specific SOD isoforms in vascular biology. This review will focus mainly on the role of individual SODs in relation to endothelium under normal conditions and in disease states. This area is important because reactive oxygen species and superoxide anion are thought to play major roles in changes in vascular structure and function in pathophysiology.
Article
Various antioxidants in foods, such as phenolic compounds and carotenoids, were proven to have anticarcinogenic activity. In the case of carotenoids, the mixture of them was found to be very effective. In fact, the development of hepatoma in the high risk group of liver cancer, was significantly suppressed by the treatment with natural carotenoids mixture. The role of nitric oxide (NO) in carcinogenesis has been pointed out, since large quantity of NO has been detected in cancer tissues, and the expression of inducible NO synthase (iNOS) was found to correlate with tumor growth and metastasis. Recently, we found that NO possessed tumor initiating activity in mouse skin carcinogenesis. It has been suggested that some parts of pathological effects induced by NO may depend on peroxynitrite, an active metabolite of NO. Thus, we accessed the tumor initiating activity of peroxynitrite, and found that treatment with peroxynitrite (initiator) plus TPA (promoter) resulted in the formation of skin tumors. Under this experimental condition, it has been proven that natural antioxidants, such as curcumin and nobiletin, showed anti-tumor initiating effect. In the case of nobiletin, suppressive effect on iNOS induction has also been demonstrated. It is of interest that suppression of iNOS induction was also observed in phytoene synthase transgenic mouse. After administration of glycerol (a lung tumor promoter), lower induction of iNOS gene was observed in lung of the phytoene producing mice, comparing with that of control mice. Combinational use of various kinds of antioxidants distributed in foods, e.g., mixture of carotenoids and flavonoids, seems to be effective methods for cancer prevention.
Article
The mechanism for the toxic superoxide radical disproportionation to molecular oxygen and hydrogen peroxide by copper-zinc superoxide dismutase (CuZnSOD) has been studied using the B3LYP hybrid density functional. On the basis of the X-ray structure of the enzyme, the molecular system investigated includes the first-shell protein ligands of the two metal centers as well as the second-shell ligand Asp122. The substrates of the model reaction are two superoxide radical anions, approaching the copper center at the beginning of two half-reactions: the first part of the catalytic cycle involving Cu+ oxidation and the second part reducing Cu2+ back to its initial state. The quantitative free energy profile of the reaction is obtained and discussed in connection with the experimental data on the reduction potentials and CuZnSOD kinetics. The optimized structures are analyzed and compared to the experimental ones. The two transition states alternate the protonation state of His61 and correspond to histidine Cu-His61-Zn bridge rupture/reformation. Modifications applied to the initial model allow the importance of Asp122 for catalysis to be estimated.
Article
To develop a novel colorimetric and automated direct measurement method for total antioxidant capacity (TAC). A new generation, more stable, colored 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS(*+)) was employed. The ABTS(*+) is decolorized by antioxidants according to their concentrations and antioxidant capacities. This change in color is measured as a change in absorbance at 660 nm. This process is applied to an automated analyzer and the assay is calibrated with Trolox. The novel assay is linear up to 6 mmol Trolox equivalent/l, its precision values are lower than 3%, and there is no interference from hemoglobin, bilirubin, EDTA, or citrate. The method developed is significantly correlated with the Randox- total antioxidant status (TAS) assay (r = 0.897, P < 0.0001; n = 91) and with the ferric reducing ability of plasma (FRAP) assay (r = 0.863, P < 0.0001; n = 110). Serum TAC level was lower in patients with major depression (1.69 +/- 0.11 mmol Trolox equivalent/l) than in healthy subjects (1.75 +/- 0.08 mmol Trolox equivalent/l, P = 0.041). This easy, stable, reliable, sensitive, inexpensive, and fully automated method described can be used to measure total antioxidant capacity.
Beneficial role of phytochemicals on oxidative stress and age-related diseases
  • C Forni
  • F Facchiano
  • M Bartoli
  • S Pieretti
  • A Facchiano
  • D 'arcangelo
  • D Norelli
  • S Valle
  • G Nisini
  • R Beninati
  • S Tabolacci
Forni C, Facchiano F, Bartoli M, Pieretti S, Facchiano A, D'Arcangelo D, Norelli S, Valle G, Nisini R, Beninati S, Tabolacci, C, Beneficial role of phytochemicals on oxidative stress and age-related diseases. Biomed Res Int., 2019; 8748253.
  • Mcds Tenório
  • N G Graciliano
  • F A Moura
  • A C Oliveira
  • M O Goulart
Tenório MCDS, Graciliano NG, Moura FA, Oliveira AC, Goulart MO, N-Acetylcysteine (NAC): Impacts on human health. Antioxidants, 2021; 10: 967-1001.