Effects of Enzymatic Activation of Bleaching Gels on Hydrogen Peroxide Degradation Rates, Bleaching Effectiveness, and Cytotoxicity

2019 ◽  
Vol 44 (4) ◽  
pp. 414-423 ◽  
Author(s):  
U Ortecho-Zuta ◽  
CC de Oliveira Duque ◽  
ML Leite ◽  
EAF Bordini ◽  
FG Basso ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radicals ◽  
Free Radical ◽  
Membrane Damage ◽  
Positive Control ◽  
Degradation Rates ◽  
Enzymatic Activation ◽  
Negative Controls ◽  
Bleaching Gels ◽  
Harmful Effects

SUMMARY Objectives: The aim of this study was to evaluate the effect of horseradish peroxidase (HRP) on the release of free radicals, bleaching effectiveness, and indirect cytotoxicity of a 35% hydrogen peroxide (HP) bleaching gel. Methods and Materials: First, HP degradation rates and free radical release were evaluated for 35% HP in contact or not with HRP (10 mg/mL). The bleaching gel associated or not with HRP was then applied (3 × 15 minutes) to enamel/dentin discs adapted to artificial pulp chambers, and the culture medium in contact with dentin surfaces (extract) was collected and exposed to cultured odontoblast-like cells. Membrane damage and viability of cells as well as oxidative stress were evaluated. Residual HP/free radical diffusion was quantified, and bleaching effectiveness (ΔE) was assessed. Unbleached discs served as negative controls. Results: The addition of HRP to the 35% HP bleaching gel enhanced the release of free radicals in comparison with plain HP gel. The 35% HP-mediated cytotoxicity significantly decreased with HRP in the bleaching gel and was associated with reduced HP/free radical diffusion through the enamel/dentin discs. ΔE values increased every bleaching session for HRP-containing gel relative to positive control, accelerating the whitening outcome. Conclusion: The enzymatic activation of a 35% HP bleaching gel with HRP accelerated HP degradation mediated by intensification of free radical release. This effect optimized whitening outcome as well as minimized residual HP and free radical diffusion through enamel and dentin, decreasing the harmful effects on odontoblast-like cells.

Analysis of the soybean metallothionein system under free radical stress: protein modification connected to lipid membrane damage

Metallomics ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1792-1804 ◽  
Author(s):  
Mireia Tomàs Giner ◽  
Elena Jiménez-Martí ◽  
Roger Bofill Arasa ◽  
Anna Tinti ◽  
Michele Di Foggia ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Protein Modification ◽  
Cell Membranes ◽  
Lipid Membrane ◽  
Metal Clusters ◽  
Membrane Damage ◽  
Stress Protein ◽  
Structural Rearrangement ◽  
Free Radical Stress

Metal clusters act as good interceptors of free radicals for four plant metallothioneins: partial deconstruction, structural rearrangement and damage transfer to cell membranes.

scholarly journals Hydrogen Peroxide Effects on Natural-Sourced Polysacchrides: Free Radical Formation/Production, Degradation Process, and Reaction Mechanism—A Critical Synopsis

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 699
Author(s):  
Chigozie E. Ofoedu ◽  
Lijun You ◽  
Chijioke M. Osuji ◽  
Jude O. Iwouno ◽  
Ngozi O. Kabuo ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radicals ◽  
Free Radical ◽  
Structural Characteristics ◽  
Radical Formation ◽  
Research Attention ◽  
Natural Sources ◽  
Polysaccharide Degradation ◽  
Free Radical Formation

Numerous reactive oxygen species (ROS) entities exist, and hydrogen peroxide (H2O2) is very key among them as it is well known to possess a stable but poor reactivity capable of generating free radicals. Considered among reactive atoms, molecules, and compounds with electron-rich sites, free radicals emerging from metabolic reactions during cellular respirations can induce oxidative stress and cause cellular structure damage, resulting in diverse life-threatening diseases when produced in excess. Therefore, an antioxidant is needed to curb the overproduction of free radicals especially in biological systems (in vivo and in vitro). Despite the inherent properties limiting its bioactivities, polysaccharides from natural sources increasingly gain research attention given their position as a functional ingredient. Improving the functionality and bioactivity of polysaccharides have been established through degradation of their molecular integrity. In this critical synopsis; we articulate the effects of H2O2 on the degradation of polysaccharides from natural sources. Specifically, the synopsis focused on free radical formation/production, polysaccharide degradation processes with H2O2, the effects of polysaccharide degradation on the structural characteristics; physicochemical properties; and bioactivities; in addition to the antioxidant capability. The degradation mechanisms involving polysaccharide’s antioxidative property; with some examples and their respective sources are briefly summarised.

scholarly journals Uji Aktivitas Antioksidan Ekstrak Buah Kluwih (Artocarpus Communis)

2018 ◽  
Vol 7 (2) ◽  
pp. 85
Author(s):  
Mohammad Arif ◽  
Nurdin Rahman ◽  
Supriadi Supriadi
Keyword(s):  
Antioxidant Activity ◽  
Free Radicals ◽  
Free Radical ◽  
Vitamin C ◽  
Positive Control ◽  
Fruit Extract ◽  
Fruit Extracts ◽  
Ic50 Value ◽  
Fruit Powder ◽  
Central Sulawesi

This study aimed to determine antioxidant activity of artocarpus camansi fruit extracts from Sigi, Central Sulawesi. This study was conducted by maceration extraction technique, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) as the source of free radicals, and vitamin C as a positive control. UV-Vis spectrophotometer was used for measuring the absorbance of artocarpus camansi fruit extracts. artocarpus camansi fruit powder was extracted by maceration using ethanol. Various concentrations of artocarpus camansi fruit extracts used were 20, 40, 60, and 80 mg/L. The results showed that the IC50 value for artocarpus camansi (artocarpus communis) fruit extract was 88.715 mg/L, whereas the IC50 value for vitamin C was 37.153 mg/L. Artocarpus camansi (artocarpus communis) fruit extracts are powerful antioxidants category based on IC50 value. The optimum percentage antioxidant activity of artocarpus camansi fruit extracts to inhibit free radical amounted to by 50.65%

Study of antioxidant potential in leaves, stems, nuts of Juglans regia L.

2012 ◽  
Vol 1 (10) ◽  
pp. 79 ◽  
Author(s):  
G. Raja* ◽  
Ivvala Anand Shaker ◽  
Inampudi Sailaja ◽  
R. Swaminathan ◽  
S. Saleem Basha ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Juglans Regia ◽  
Radical Scavenging ◽  
Antioxidant Compounds ◽  
Free Radical Damage ◽  
Radical Damage

Natural antioxidants can protect the human body from free radicals and retard the progress of many chronic diseases as well as lipid oxidative rancidity in foods. The role of antioxidants has protected effect against free radical damage that may cause many diseases including cancer. Primary sources of naturally occurring antioxidants are known as whole grains, fruits, and vegetables. Several studies suggest that regular consumption of nuts, mostly walnuts, may have beneficial effects against oxidative stress mediated diseases such as cardiovascular disease and cancer. The role of antioxidants has attracted much interest with respect to their protective effect against free radical damage that may cause many diseases including cancer. Juglans regia L. (walnut) contains antioxidant compounds, which are thought to contribute to their biological properties. Polyphenols, flavonoids and flavonols concentrations and antioxidant activity of Leaves, Stems and Nuts extract of Juglans regia L. as evaluated using DPPH, ABTS, Nitric acid, hydroxyl and superoxide radical scavenging activity, lipid peroxidation and total oxidation activity were determined. The antioxidant activities of Leaves, Stems and Nuts extract of Juglans regia L. were concentration dependent in different experimental models and it was observed that free radicals were scavenged by the test compounds in all the models.

The effect of cation concentration on the nitrogen splitting constant of nitroxide free radicals

1990 ◽  
Vol 55 (10) ◽  
pp. 2377-2380
Author(s):  
Hamza A. Hussain
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Bonding ◽  
Free Radicals ◽  
Esr Spectroscopy ◽  
The Other ◽  
Tetraethylammonium Bromide ◽  
Splitting Constant ◽  
The One ◽  
Positively Charged ◽  
Two Equilibria

Nitroxide free radicals prepared from diethylamine, piperidine and pyrrolidine by oxidation with hydrogen peroxide were studied by ESR spectroscopy. The changes in the 14N splitting constant (aN) caused by the addition of KBr or tetraethylammonium bromide were measured in dependence on the concentration of the ions. For diethylamine nitroxide and piperidine nitroxide, the results are discussed in terms of two equilibria: the one, involving the anion, is associated with a gain or loss of hydrogen bonds to the nitroxide oxygen atom, the other is associated with the formation of solvent shared units involving the cation, which results in changes in the hydrogen bonding strenght. The large increase in the aN value in the case of pyrrolidine nitroxide is explained in terms of an interaction from one side of the positively charged N atom; the increase in aN in the case of diethylamine and piperidine nitroxides is explained in terms of interactions with both sides of the positively charged N atom.

THE KINETICS OF THE THERMAL REACTIONS OF ETHYLENE OXIDE

1963 ◽  
Vol 41 (12) ◽  
pp. 2956-2961 ◽  
Author(s):  
M. Lynne Neufeld ◽  
Arthur T. Blades
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Ethylene Oxide ◽  
Thermal Reactions ◽  
Kinetics Of

The thermal reactions of ethylene oxide in the presence of an excess of propylene have been studied as a function of pressure and it has been found that there are two sets of products, acetaldehyde and free radicals, presumably methyl and formyl. These products are believed to arise from an excited acetaldehyde intermediate. Some evidence has been obtained for the occurrence of a surface-catalyzed rearrangement to acetaldehyde but the free radical products are uninfluenced by surface.

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