Determination of Cobalt(II)-Hydrogen Peroxide-Induced DNA Oxidative Damage and Preventive Antioxidant Activity by CUPRAC Colorimetry

The classical Fenton system composed of Fe(II) and H2O2 uses harsh oxidative conditions and cannot realistically simulate physiological oxidations which are less severe. Here, reactive oxygen species (ROS) were generated with a combination of CoSO4 and H2O2 to provide milder conditions. DNA was used as a biologically meaningful probe for monitoring the oxidative conversion. Oxidative hazard on DNA was accomplished in ammonia/ammonium chloride buffer at 37 degrees C, and the Fenton reaction was stopped with trichloroacetic acid (TCA). A suitable aliquot of this solution was added to cupric ion reducing antioxidant capacity (CUPRAC) reaction mixture, and the absorbance at 450 nm was recorded. The oxidized species derived from DNA were CUPRAC-reactive while intact DNA was not. The protective effects of antioxidants (AOxs), known to have radical scavenging effects, were tested; green tea and a synthetic fetal bovine serum (FBS) were also successfully used as real ROS scavengers. Although the classical iron-based Fenton procedure applied in ethanol medium generated CUPRAC-responsive products, the proposed system was perfectly ethanol-tolerant, enabling the CUPRAC measurement of DNA oxidation products against an unaffected reagent blank. The protective effects of phenolic antioxidants, perfectly solubilized in ethanol, could also be measured

The Protective Role of Hippophae rhamnoides L. on Rat Brain and Liver Tissues Exposed to Cold Plus Immobilization Stress Model

AIM: To investigate the protective role of Hippophae rhamnoides L. (Sea buckthorn, SBT) in cold plus immobilization stress-induced oxidative and nitrosative stress in rats. MATERIAL and METHODS: Thirty-two Wistar albino rats were randomly divided into four groups: control (i.p. physiological saline), SBT (i.p. 200 mg/kg/48h SBT extract), stress (i.p. physiological saline; 6-h cold plus immobilization stress) and SBT+stress (i.p. 200 mg/kg/48h SBT; 6-h cold plus immobilization stress).* In liver and brain tissues 3-nitrotyrosine levels were determined by ELISA while total antioxidant capacity, total thiol, total glutathione, total nitrite+nitrate levels, superoxide dismutase and glutathione peroxidase activities were measured using colorimetric methods. RESULTS: In the SBT+stress group, the total glutathione levels and glutathione peroxidase activities were significantly higher in both tissues, whereas the total nitrite+nitrate levels and superoxide dismutase activities decreased compared with the stress group. The 3-nitrotyrosine levels as oxidative and nitrosative stress markers were found to be significantly higher in SBT+stress group in both tissues than in the control. No significant differences were found between the stress and SBT+stress groups in the liver. CONCLUSION: The results show that SBT has antioxidant properties against cold plus immobilization stress-induced oxidative and nitrosative stress and that it can be recommended as a natural antioxidant and nutritional supplement

Sulfate radical formation by Cr(III) activation of peroxydisulfate Diphenylcarbazide spectrophotometric determination of sulfate radical and its scavenging activity

Even though sulfate anion radical (SO4 center dot) is a very reactive oxidant used in advanced oxidation processes, a reliably selective and simple colorimetric method for determining this radical can hardly be found. Peroxydisulfate (S2O82 center dot) or peroxymonosulfate (HSO5 center dot) can be activated with transition metal ions to produce SO4 center dot. We have discovered that Cr(III) can be an activator for persulfate, generating Cr(VI) along with SO4 center dot. By measuring the emerging chromate with diphenyl carbazide (DPC) spectrophotometry at 542 nm, we could measure both the formation of SO4 center dot and its scavenging with antioxidant compounds. We could also investigate a number of UV-absorbing SO4 center dot scavengers which could not be measured with other UV spectrometric methods. In addition to conventional antioxidants (phenolics such as quercetin, catechin, epicatechin, caffeic acid, thiols like cysteine and N-acetyl cysteine, and ascorbid acid), nitro-aromatics (represented by 2,4,6-trinitrophenol and 2,4-dinitrophenol) used in ammunition formulations could also be measured as scavengers. The presence of scavengers caused a reduction in the amount of Cr(VI) generated, where the difference in absorbance (Delta A) of chromate - with respect to the DPC method - in the absence and presence of scavengers was a linear function of SO4 center dot scavenging capacity. Ethanol and tert-butanol were tested as solvents to show the selectivity of the method for SO4 center dot. The method was statistically compared to a suitably modified ABTS/persulfate assay. The efficiency order of sulfate radical scavengers was determined and ranked (Spearman's test) using both the proposed method and modified ABTS/persulfate method to reveal a moderate correlation. (C) 2021 Elsevier B.V. All rights reserved