Peroxy Research Articles

EFFECT OF DENTURE CLEANSERS ON HARDNESS OF ACRYLIC SOFT LINER

Plasticizer is the content of the soft liner (with soft acrylic polymer (poly ethylmethacrylate)) or denture tissue conditioner material that maintains the soft said material. However, it will release as a result of the saliva or water solution being absorbed that could be effected on the acrylic soft liner physical properties such as a hardness. Selection of the denture cleanser is very important to minimize its impact, which is the traditional plant cinnamon (Cinnamomum burmani) can be used as an alternative of natural denture cleansure agents besides alkaline peroxide chemicals used frequently. The aim of this study was to determine the effect of different denture cleansers on hardness of acrylic soft liner. Method: Eighteen cylindrical acrylic soft liner samples (15mm x 10 mm (ASTM: D-2240 64T)) were divided into 3 groups : group I aquadest immersion, group II alkaline peroxide immersion and group III cinnamon immersion. The measurement of acrylic soft liner hardness was done using Shore A hardness D2240 after 7 days of immersion. The results were submitted to one-way ANOVA and post hoc Bonferroni. Results: The highest average of acrylic soft liner hardness was shown by alkaline peroxide immersion group followed by cinnamon immersion group and aquadest immersion group sequentially. There was a significant difference between all groups (p<0.05). Conclusion: There was effect of different denture cleansers on hardness of acrylic soft liner. Keywords: soft liner, denture cleanser, cinnamon

Adsorption of Oligomeric Peroxides on Aerosil and Magnesium Oxide and Their Behavior on the Water-Air Phases Interface

Oligomeric peroxide adsorption of sebacic acid on aerosil and magnesium oxide was studied. Adsorption process parameters were found. It is shown that the adsorption takes place through the hydrogen bonds formation between OH– groups of adsorbents surface and peroxide groups. The adsorption process suggests the behavior of peroxide compounds on the water-air phase’s interface. Monomolecular film formations on water surface for oligomeric peroxides were studied. It was found that calculated values of the area extrapolated to zero pressure (S0) depend on the solvent which was used to apply the peroxide in the phases interface. Oligomeric peroxide monolayers considered as condensation-type monolayers. Thermal decomposition of oligomeric peroxide and its di- and monoperoxide analogues was studied. It was shown that total constants of thermal degradation rate k for oligomeric peroxide are higher than those for di- and monoperoxide analogues. There is a correlation between S0 calculated values and the constants of thermal degradation rate for oligoperoxide. The less is S0 value the higher is k value. The conformational state of the macromolecule was preserved during transferring the oligomeric peroxide solution in an organic solvent to the phases interface that affects k values.

Evaluation of hydrogen peroxide-assisted endoscopic ultrasonography-guided necrosectomy in walled-off pancreatic necrosis

Hydrogen peroxide is a liquid that functions in mechanical removal of the necrotic tissue via the elimination of tissue debris.In this study, we aimed to evaluate the effectiveness of the use of hydrogen peroxide in necrosectomy treatment of walled-off pancreatic necrosis.Records of 24 patients who were diagnosed with pancreatic necrosis or walled-off pancreatic necrosis and underwent endoscopic necrosectomy (EN) were retrospectively assessed. Patients were divided into 2 groups; hydrogen peroxide used for treatment or not used, and these 2 groups were compared.A total of 24 patients underwent endoscopic intervention for walled-off pancreatic necrosis. Procedural success was comparable between the 2 groups. During the post-procedural follow-up, the duration of the hospital stay, recurrence, and complication rates were found to be similar in both groups. The mean number of the endoscopic interventions was significantly lower in the hydrogen peroxide group (4.2 ± 1.4 vs 6.1 ± 4.2; P = .01).The use of hydrogen peroxide for EN in walled-off pancreatic necrosis patients seems to have similar efficiency and safety. However, it can be said that the use of hydrogen peroxide could reduce the number of endoscopic procedures.

The effect of different irrigation solutions on fracture healing in a rat femur fracture model.

Objectives This study aims to evaluate and compare radiological, biomechanical, histopathological, histomorphometric and immunohistochemical effects of povidone iodine (PVP-I), hydrogen peroxide (HPO) and chlorhexidine gluconate (CHG) on fracture healing in their minimum cytotoxic and most efficient concentrations.Materials and methods This experimental animal study, conducted between April 2018 and January 2019, included 48 male Sprague Dawley® rats (weighing 356 g; aging 9 weeks) which were randomly divided into four groups: control (saline), HPO, PVP-I and CHG. Rat model of femoral fracture was established and intramedullary fixation was applied. Solutions were applied to fracture region in determined concentration and time, and all subjects were sacrificed on Day 28. Extracted femurs were investigated radiologically by micro-computed tomography. Then, all groups were divided into two random groups to be evaluated biomechanically, histopathologically, histomorphometrically and immunohistochemically.Results In histopathological evaluation, inflammation score of CHG group was significantly lower than other groups, and inflammation score of PVP-I group was significantly lower than control and HPO groups (p<0.05). Biomechanically, flexural strength (σbend) (megapascal) values of CHG and control groups showed similar results, but there was no significant difference between all groups (p>0.05). In immunohistochemical localization of bone morphogenic protein (BMP)-4, osteoblast and chondroblast histoscores (H-scores) of HPO group were significantly lower than other groups, and chondroblast H-score in CHG group was lower than control and PVP-I groups (p<0.05). In immunohistochemical localization of BMP-7, osteoblast H-score was significantly higher in CHG group than other groups (p<0.05).Conclusion We determined that CHG 0.05% solution had no negative effect on the fourth week of fracture healing histopathologically, immunohistochemically and biomechanically, and is an alternative irrigative to normal saline.

Diarylalkanoids as Potent Tyrosinase Inhibitors from the Stems of Semecarpus caudata.

From a CHCl3-soluble extract of the stems of Semecarpus caudata (Anacardiaceae), two new diarylalkanoids, semedienone (1) and semetrienone (2), were isolated. Their structures were elucidated based on NMR spectroscopic data interpretation. These compounds possess strong tyrosinase inhibitory activity with the IC50 values of 0.033 and 0.11 μM, respectively. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. Accordingly, semedienone (1) showed good interactions with the peroxide group and amino acid residues. The biosynthesis of the isolated diarylalkanoids was proposed.

Assessment of a novel bleaching agent formula containing 35% hydrogen peroxide and titanium tetrafluoride: an in vitro study.

This study developed experimental gels containing titanium tetrafluoride (TiF4) combined with commercial 35% hydrogen peroxide (HP), and evaluated bleaching efficacy and pH of the gels, and mineral content and morphology of enamel submitted to these treatments. In phase-1, different stock gels mixed with TiF4 were combined with HP. In phase-2, the selected gels were tested on enamel/dentin specimens (n=8): HP; HP and Natrosol+TiF4 (HPnT); HP and Natrosol+Chemygel+TiF4 (HPncT); HP and Aristoflex+TiF4 (HPaT). Bleaching was performed in four sessions (3x15min-application/session). Color (CIEL*a*b*) and whiteness index (WID) were measured after each session, whereas whiteness index differences (ΔWID), color alteration (CIELab-ΔE, CIEDE2000-ΔE00), enamel morphology and pH, at end of bleaching therapy. The change in Knoop microhardness (ΔKHN) was compared before and after bleaching. Data were analyzed by two-way repeated measures ANOVA and Bonferroni (CIEL*, a*, b*), one-way ANOVA and Tukey (ΔWID, ΔE, ΔE00), and LSD (ΔKHN) tests (α=5%). SEM and pH measurements were submitted to descriptive analysis. No differences were observed in lightness (L*) or WID among the groups (p > 0.05), but HP exhibited lower b* values (p<0.05), higher ΔWID than HPnT, and the highest ΔE among the groups (p < 0.05). No differences in ΔE00 were observed between HP and HPncT (p > 0.05), and HPncT showed higher ΔKHN than HP (p < 0.05). HP presented pH values closer to neutral (6.9), whereas experimental agents showed acidic pH values (2.3-3.9). No morphological changes were observed in HP or HPncT groups. HPncT was able to bleach the enamel and maintain enamel microhardness and surface integrity, even at low pH.

Organocatalytic sulfoxidation

Treatment of a sulfide with a catalytic amount of a 1,3-diketone in the presence of silica sulfuric acid as a co-catalyst and hydrogen peroxide (50% aq) as the stoichiometric oxidant leads to the corresponding sulfoxide product. The reaction is effective for diaryl, aryl-alkyl and dialkyl sulfides and is tolerant of oxidisable and acid sensitive functional groups. Investigations have shown that the tris-peroxide 2, formed on reaction of pentane-2,4-dione with hydrogen peroxide under acidic reaction conditions, can oxidise two equivalents of sulfide using the exocyclic peroxide groups whereas the endocyclic peroxide remains intact. Calculations provide a mechanism consistent with experimental observations and suggest the reaction proceeds via an initial acid catalysed ring opening of a protonated tris-peroxide prior to oxygen transfer to a sulfur nucleophile.

PH-dependent rearrangement determines the iron-activation and antitumor activity of artemisinins

The action mechanisms of artemisinins remains elusive for decades, and one long-standing question is whether the indispensable peroxide group is activated by iron or heme. Although heme usually reacts faster with artemisinins than iron does, we have found that rearrangement of dihydroartemisinin (DHA) into monoketo-aldehyde-peroxyhemiacetal (MKA) under physiological conditions can significantly enhance its reaction towards iron. The rearrangement is pH-dependent and the derived MKA is identified by LC-MS in the cellular metabolites of DHA in cancer cells. MKA reacts quickly with ferrous irons to afford reactive carbon-centered radicals and can inhibit enzyme activities in vitro. Moreover, MKA oxidizes ferrous irons to ferric irons, which may explain the effect of DHA on decreasing cellular labile iron pool (LIP). Both addition of exogenous iron and increase in LIP via triggering ferroptosis can enhance the cytotoxicity of DHA against cancer cells. While artesunate (ATS) can also decompose to MKA after hydrolyzing into DHA, the other artemisinins of lower antitumor activity, e.g. artemisinin (ART), artemether (ATM) and arteether (ATE), exhibit negligible hydrolysis and rearrangement under the same conditions. Our study reveals the vital role of molecular rearrangement to the activation and activity of artemisinins and provides a new strategy for designing antitumor molecules containing endoperoxide group.

Effects and mechanism of copper oxide nanozymes on wound healing of full-thickness skin defects in diabetic mice

Effects and mechanism of copper oxide nanozymes on wound healing of full-thickness skin defects in diabetic mice

The role of Rheum ribes roots alcoholic extract in reducing the effect of oxidative stress on the reproductive system of male rats

The current study investigated the effect of Rheum ribes extracts alone or synergistically with zinc in the oxidative-antioxidatve status in semen of male rats exposed to oxidative stress with hydrogen peroxide (0.5%) and compared these effects with the role of vitamin E. 40 Male rats were used aged (12-14) weeks and weighed (130_220) g and randomly divided into (8) groups, 5 animals for each as follows:&#x0D; 1-Control group, 2-hydrogen peroxide group (H2O2 0.5%), 3-Ethanolic root extract of Rheum root + zinc (100 mg / kg bw) + H2O2, 4-ethanolic extract of Rheum root + vitamin E (500 mg / kg),+ H2O2,5-ethanolic extract of Rheum root (500 mg / kg bw) + H2O2,6-Zinc group (100 mg / kg body weight), 7-vitamin E 500 (mg/kg body weight), 8-ethanolic extract of Rheum roots. The results showed a significant increase (P≤0.05) in the level of malonadialdehyde (MDA) and a significant decrease in the levels of antioxidant enzymes, catalase enzyme (Cat), superoxide dismutase (SOD), reduced glutathione (GSH) and glutathione peroxidase (GPx) and total antioxidant level in semen. The treatment of rats exposed to hydrogen peroxide (0.5%) with the extract of the roots of the Rheum showed a significant decrease in the level of malonadialdehyde compared with the group of hydrogen peroxide and a significant increase in the levels of antioxidants enzymes in semen. The use of the extract synergistically with zinc sulphate (100 mg / kg bw) and vitamin E (500 mg / kg bw) showed similar results to the control group. Current results indicate the role of the alcoholic extract of the roots of the Rheum ribes plant in reducing the effects of oxidative stress and thus improve the function of the reproductive system in male rats

Synthesis of Epoxyperoxides and Peroxide Derivatives of -D-Galactopyranose Based Thereon

New epoxide-containing peroxides have been synthesized via the interaction between epichlorohydrin and ditertiary -hydroxyalkyl peroxides. The effect of reaction conditions on both the yield and composition of the reaction products has been established. Through the reactions of either the synthesized epoxide-containing peroxides with 1,2;3,4-di-O-isopropylidene--D-galactopyranose or 6-O-glycidyl-1,2;3,4-di-O-isopropylidene--D-galactopyranose with the -hydroxyalkyl peroxides, new peroxide derivatives with ditertiary and primary-tertiary peroxide groups have been synthesized successfully. The decomposition of the developed substances has been studied by complex thermal analysis and the kinetic parameters of the thermolysis have been determined.

Degradation Features Of Polyethylene And Gelatin Compositions

In this work, biodegradable properties of gelatin and polyethylene compositions, in addition to, influence of ultra violet radiation and peroxide groups were studied. In order to obtain thermoplastic gelatin water and glycerin were used as a plasticizer. For polyethylene/gelatin blends, to provide compatibility polyethylene functionalized with maleic anhydride. It was found that as gelatin content increases, biodegradation also grows while mechanical properties (elastic module and yield strength) decrease.

An Effective Hybrid Heterogeneous Catalyst to Desulfurize Diesel: Peroxotungstate@Metal-Organic Framework.

A peroxotungstate composite comprising the chromium terephthalate metal–organic framework MIL-101(Cr) and the Venturello peroxotungstate [PO4{WO(O2)2}4]3− (PW4) has been prepared by the impregnation method. The PW4@MIL-101(Cr) composite presents high catalytic efficiency for oxidative desulfurization of a multicomponent model diesel containing the most refractory sulfur compounds present in real fuels (2000 ppm of total S). The catalytic performance of this heterogeneous catalyst is similar to the corresponding homogeneous PW4 active center. Desulfurization efficiency of 99.7% was achieved after only 40 min at 70 °C using H2O2 as an oxidant and an ionic liquid as an extraction solvent ([BMIM]PF6, 2:1 model diesel/[BMIM]PF6). High recycling and reusing capacity was also found for PW4@MIL-101(Cr), maintaining its activity for consecutive oxidative desulfurization cycles. A comparison of the catalytic performance of this peroxotungstate composite with others previously reported tungstate@MIL-101(Cr) catalysts indicates that the presence of active oxygen atoms from the peroxo groups promotes a higher oxidative catalytic efficiency in a shorter reaction time.

Studying and imparting moisture absorption qualities of the new wood based bio-composite material

The paper reviews the method of creating a new bio-composite material based on birch wood and describes the mechanism of interaction of used motor oil with birch wood by infrared spectroscopy involved. It also provides data on the moisture absorption of the newly obtained composite. Used motor oil has high hydrophobic and antiseptic properties. The main chemical changes in oils occur as a result of its oxidation during engine operation under the temperature influence. However, the spectrum of spent engine oil is distinguished by the appearance of three new peaks: the wide peak of 3600-3000 cm−1, which is formed during characteristic vibrations of the OH group, indicating water cut in the engine oil, a narrow peak of 1740 cm−1, characteristic of stretching vibrations of the carbonyl group (C = O). In addition to these peaks, the other peak was detected at the 1150 cm−1 frequency and, yet, another weakly pronounced peak of 970 cm−1, which correspond to stretching vibrations of the peroxide group (C-O-O). The mechanism for impregnating wood with used engine oil has been developed. The moisture absorption of wood impregnated with spent engine oil is 3 times less than that of natural wood.

Evaluation of the Pharmacophoric Role of the O-O Bond in Synthetic Antileishmanial Compounds: Comparison between 1,2-Dioxanes and Tetrahydropyrans.

Leishmaniases are neglected diseases that can be treated with a limited drug arsenal; the development of new molecules is therefore a priority. Recent evidence indicates that endoperoxides, including artemisinin and its derivatives, possess antileishmanial activity. Here, 1,2-dioxanes were synthesized with their corresponding tetrahydropyrans lacking the peroxide bridge, to ascertain if this group is a key pharmacophoric requirement for the antileishmanial bioactivity. Newly synthesized compounds were examined in vitro, and their mechanism of action was preliminarily investigated. Three endoperoxides and their corresponding tetrahydropyrans effectively inhibited the growth of Leishmania donovani promastigotes and amastigotes, and iron did not play a significant role in their activation. Further, reactive oxygen species were produced in both endoperoxide- and tetrahydropyran-treated promastigotes. In conclusion, the peroxide group proved not to be crucial for the antileishmanial bioactivity of endoperoxides, under the tested conditions. Our findings reveal the potential of both 1,2-dioxanes and tetrahydropyrans as lead compounds for novel therapies against Leishmania.

Evaluation of safety and efficacy of hydrogen peroxide stabilized cream for treatment of mild to moderate acne vulgaris in comparison with benzoyl peroxide gel - double blinded, randomized control study

Acne is defined as a chronic inflammatory disorder of the pilosebaceous unit, which is characterized by comedones, seborrhea, pustules, nodules, pseudocysts and scarring, in some cases. Benzoyl peroxide (BP) is a time tasted molecule in the management of acne. In current study we have tried to compare efficacy of benzoyl peroxide with hydrogen peroxide (HP) in acne vulgaris (AV).To study efficacy and local tolerability of BP and HP in Acne Vulgaris treatment. To compare the efficacy and local tolerability of BP gel and HP cream in a Acne Vulgaris (GRADE 1 AND 2) treatment.A double blinded, randomised control study for the duration of 18 months was carried out in which a total of 150 patients of acne vulgaris (Grade 1 &amp; 2) between the age of 13-30 years of both genders were recruited, which were divided in two groups, with one group treated with benzoyl peroxide gel 2.5% and second group being treated with hydrogen peroxide cream. All the data analysis was done using IBM SPSS ver. 20 software.Both drugs were found to be equally efficacious in reducing acne lesions. Hydrogen peroxide group experienced less side-effects as compared to benzoyl peroxide group.Hydrogen peroxide and benzoyl peroxide are equally efficacious.: In acne grade one and two benzoyl peroxide and hydrogen peroxide are equally efficacious though hydrogen peroxide has less adverse effect.

The influence of violet LED light on tooth bleaching protocols: In vitro study of bleaching effectiveness.

Employing violet LED on tooth bleaching is a recent but promising technique. This study aimed to assess the bleaching effectiveness of violet light-emitting diodes (LEDs) associated or not with bleaching gels containing hydrogen peroxide (HP) or carbamide peroxide (CP). seventy bovine incisors were randomly assigned into 7 groups (n = 10) according to the technique and whitening product used. Group C: Artificial saliva (placebo); Group HP L-: three sessions of HP at 35 % without light activation; Group CP L-: three weeks of CP at 16 % for 4 h/day; Group HP CP L-: three sessions of HP at 35 % without light activation + 2 weeks of CP at 16 %, for 4 h/day; Group LED: four sessions with violet LED; Group HP L+: three sessions with HP at 35 % + violet LED; Group CP L+: three weeks with CP at 16 % for 4 h/day + violet LED. Color changes (ΔE and ΔL) were measured with a portable digital spectrophotometer. The results were similar between the groups of bleaching protocols, demonstrating that the use of the violet LED did not influence bleaching effectiveness when using HP 35 % or CP 16 % after 3 sessions. In addition, the use of the violet LED alone obtained ΔE values ​​similar to the protocols with the use of peroxides, however less variation of ΔL was observed for this group. The use of violet LEDs associated or not with bleaching gels was effective for tooth whitening. In addition, it was also concluded that the physical lightening technique with violet LED used alone produced less variation in dental brightness.

The use of retinoic acid in association with microneedling in the treatment of epidermal melasma: efficacy and oxidative stress parameters.

This study aimed to evaluate the effectiveness of isolated treatment with retinoic acid and its combination with the microneedling technique in facial melasma, seeking to associate these results with possible oxidative damage. This is a blinded randomized clinical trial with 42 women with facial melasma (skin phototype I-IV), randomized into Group A (microneedling and 5% retinoic acid) or Group B (5% retinoic acid alone). Four procedures were applied with 15days intervals (4 blood collections). Clinical improvement was assessed using the Melasma Area Severity Index (MASI). Serum oxidative stress levels were evaluated by protein oxidation (carbonyl), lipid peroxidation (TBARS) and sulfhydryl groups, as well as enzyme activities of superoxide dismutase (SOD) and catalase (CAT). The statistical analyzes were performed by generalized estimation equation (GEE). There was a reduction in MASI scale and TBARS levels in both groups over time (p < 0.05), with no difference between groups (p = 0.416). There was also a substantial increase in the carbonyl levels at 30days (p = 0.002). The SOD activity decreased after 30days, regardless of group (p < 0.001), which was maintained after 60days. In Group A, there was a reduction in sulfhydryl levels at 60days (p < 0.001). It is important to highlight that both groups demonstrated efficacy in the clinical improvement of melasma within at least 60days, reducing the MASI score by almost 50%. However, microneedling with retinoic acid seems to be the worst treatment because there is a reduction in the non-enzymatic antioxidant defense, which is important to protect against oxidative stress.

Structurally characterized new alkyl- and alkenyl-gallium peroxides having interesting structural motifs

Reaction of lithium gallium hydride, LiGaH4, with one equivalent of tert-butyllithium generated lithium(tert-butyl)trihydridogallate, Li[tBuGaH3] (1), as colorless solid via LiH elimination. Treatment of 1 with four equivalents of tert-butyl hydrogenperoxide and subsequent crystallization generated few colorless crystals at -35 °C. Single crystal X-ray diffraction study showed the formation of a (tert butyl) galliumperoxide [tBu-Ga(OOtBu)2O(H)-Li(HOtBu)2]2 (2) where a strongly reducing “tBu-Ga” group is situated intact to two strongly oxidizing “Ga-O-O-tBu” moieties. Further, two such alkyl-galliumperoxo units dimerizes through hydroxolithium bridges. A close look at the single crystal X-ray structure of 2 show the presence of strong hydrogen bonding interactions between the peroxide oxygen and hydroxy group of tert-butanol, which are coordinated to the lithium ions. Similarly, the first alkenyl-gallium peroxide was generated via reaction of [Ph-CH=C(SiMe3)GaH2tBuLi] (3) with three equivalent of tert-butyl hydrogen peroxide. Single crystal X-ray diffraction study showed the formation of an alkenyl-gallium peroxide [Ph-CH=C(SiMe3)Ga(OOtBu)3Li]2 (4) via elimination of two equivalents of hydrogen and one equivalent of isobutane where three tert-butylperoxo groups along with an alkenyl group are attached concurrently to a single gallium atom. In addition, each of the lithium atoms are coordinated with four different oxygen atoms of two different peroxide groups.

Thermal Safety Performance Evaluation for Typical Free Radical Polymerization Initiator of Tert‐butyl Peroxypivalate

AbstractTert‐butyl peroxypivalate is a typical free radical polymerization initiator due to the active O−O peroxide group, and it is a thermal instability material. To evaluate the thermal safety of tert‐butyl peroxypivalate, Dewar test, Differential Scanning Calorimetry (DSC) and Accelerating Rate Calorimeter (ARC) were used to study the self‐accelerating decomposition temperature (SADT), thermal performance parameters and kinetic parameters. The results of DSC reveal that the onset decomposition temperature of the initiator was 76.30 °C. The apparent activation energy (Ea) was 91.86 kJ mol−1 by Kissinger method. In ARC test, the onset decomposition temperature was 40.64 °C. The adiabatic temperature of the reaction was 86.68 °C, and the apparent activation energy was 120.14 kJ mol−1. The results of Dewar test show that the SADT of the initiator was 38 °C. The simulated SADT value by thermal analysis software (AKTS) was about 35 °C which was basically consistent with the results of Dewar test.