Biochemical Aspects of Fatty Liver
Robert G. Meeks, Steadman D. Harrison, Richard J. Bull in Hepatotoxicology, 2020
The second microsomal pathway represents only a bypass from the first one. In fact, flavoprotein can release one electron to oxygen, thus forming the superoxide anion . This can act as a further hydrogen acceptor, thus producing hydrogen peroxide, H2O2. In the presence of catalase, mostly present in peroxisomes, H2O2 is decomposed to water and oxygen, which can oxidize ethanol to acetaldehyde. The production of the superoxide anion can occur independently upon the nature of the attacked substrate, the only condition being the presence of excess substrate with reference to the amount of oxygen available. Therefore, formed during the oxidation of whatsoever substrate can oxidize ethanol. The demonstration of this possibility has been for a long time the main argument of the opponents to the theory of the existence of MEOS as a direct ethanol-oxidizing enzymatic chain.
The Promising Antiradical Potential of Castanospermum australe A. Cunn. and C. Fraser ex Hook.
Parimelazhagan Thangaraj in Medicinal Plants, 2018
Hydrogen peroxide is not very reactive, but sometimes it is toxic to cells because it may give rise to hydroxyl radicals in the cells (Halliwell 1991). Therefore, removing H2O2 is very important for the antioxidant defence in cell or food systems. Dietary polyphenols have also been shown to protect mammalian and bacterial cells from cytotoxicity induced by hydrogen peroxide, especially compounds with the orthodihydroxy phenolic structure, quercetin, catechin, gallic acid ester and caffeic acid ester (Nakayama 1994). The results can be correlated to the ability of polar organic solvents to extract phenolics, tannins and flavonoids of bark, which showed maximum scavenging of hydrogen peroxide when compared to other parts. The lower percentage of the activity of samples obtained by maceration reveals that the active components responsible for hydrogen peroxide reduction may be heat-stable compounds, which can be extracted by the hot percolation methods such as Soxhlet extraction. Therefore, the ethanol extracts of bark and leaf C. australe can be used as a potent hydrogen peroxide scavenger in body systems.
The Science of Tooth Whitening
Linda Greenwall in Tooth Whitening Techniques, 2017
Whitening agents mainly consist of hydrogen peroxide. The empirical formula for hydrogen peroxide is H2O2. The structural formula is HO–OH (Kelleher 2008). The whitening agents act by a redox reaction with the discolored substrate. When the whitening agent is placed onto the teeth, reactive oxygen is released; the discolored substrate is chemically reduced and transformed into a colorless material (McEvoy 1989). The oxidation reaction occurs when the peroxide diffuses through the dentin structure and into the peritubular dentin (Chng et al. 2005). See Figure 2.1.
Accidental ingestion of 3% hydrogen peroxide in the neonatal period
Published in Baylor University Medical Center Proceedings, 2023
Seda Aydoğan, Nurdan Dinlen Fettah, Hasan Akduman, Ayşegül Zenciroğlu
Hydrogen peroxide (H2O2) is a colorless and odorless liquid with an oxidizing agent used in most household disinfectants. It is used as a general household disinfectant, in nonchlorine bleach, as a contact lens disinfectant, in hair coloring and some tooth whitening products, as well as in the chemical industry and for medical sterilization.1 Hydrogen peroxide can come in different concentrations, from 3% to 90%;2 generally, severe H2O2 toxicity occurs with a 35% concentration. Concentrated H2O2 is caustic and may cause local tissue damage upon exposure.3 The toxicity can be evaluated with three mechanisms: lipid peroxidation, corrosive damage, and oxygen gas formation.3 Hydrogen peroxide toxicity from accidental ingestion has generally been seen in adults. We describe a newborn who was given H2O2 accidentally by his father.
Effect of taxifolin on cisplatin-associated oxidative optic nerve damage in rats
Published in Cutaneous and Ocular Toxicology, 2021
Ibrahim Ahiskali, Irmak Ferah Okkay, Renad Mammadov, Ufuk Okkay, Ferda Keskin Cimen, Nezahat Kurt, Halis Suleyman
TAS determines the total antioxidant capacity of different antioxidant molecules in a tissue [24] while TOS determines the total oxidant capacity [25]. TOS and TAS levels of tissue homogenates were determined using a novel automated measurement method and commercially available kits (Rel Assay Diagnostics, Turkey), both developed by Erel [24,25]. The TAS method was based on the bleaching of characteristic colour of a more stable ABTS [2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)] radical cation by antioxidants and, measurements were performed at 660 nm. The results were expressed as nmol hydrogen peroxide (H2O2) equivalent/L. In TOS method, the oxidants presented in the sample oxidized the ferrous ion-o-dianisidine complex to ferric ion. The oxidation reaction was enhanced by glycerol molecules, which had been abundantly present in the reaction medium. The ferric ion produced a coloured complex with xylenol orange in an acidic medium. The colour intensity, which could be measured at 530 nm spectrophotometrically, was related to the total amount of oxidant molecules presented in the sample. The results were expressed as µmol Trolox equivalent/L.
Effect of 900-, 1800-, and 2100-MHz radiofrequency radiation on DNA and oxidative stress in brain
Published in Electromagnetic Biology and Medicine, 2019
Mehmet Esref Alkis, Hakki Murat Bilgin, Veysi Akpolat, Suleyman Dasdag, Korkut Yegin, Mehmet Cihan Yavas, Mehmet Zulkuf Akdag
TOS measurement was performed by the fully automatic colorimetric measurement method developed by Erel (2005). In this method, the oxidants present in the sample oxidize the ferrous (Fe2+) ion-o-dianisidine complex to the ferric ion. Glycerol molecules that are abundant in the reaction medium accelerate oxidation reactions. In the acidic environment, ferric ions create a colorful complex with xylene orange. The color intensity measured spectrophotometrically is directly proportional to the total amount of oxidant molecules present in the sample. The analysis is calibrated with hydrogen peroxide and the results are expressed in micromolar hydrogen peroxide equivalents per liter (μmol H2O2 Equiv./Liter). Total oxidant capacity measurement was performed using a TOS kit (Rel Assay, Turkey, Catalog No. RL0024) and read on the plate reader (Thermo Scientific Multiskan FC, 2011 −06, USA) at 530-nm wave length.
Related Knowledge Centers
- Antiseptic
- Chemical Compound
- Oxidizing Agent
- Oxygen
- Peroxidase
- Reactive Oxygen Species
- Properties of Water
- Bleach
- Stabilizer
- Thermal Decomposition