Benzoyl Peroxide System Research Articles

Radical-scavenging and Pro-/anti-inflammatory Activity of Tetracycline and Related Phenolic Compounds With or Without Visible Light Irradiation.

Microbial tetracycline (TC) pastes have been employed to treat oral bacterial infection. In the present study, we investigated the kinetic radical-scavenging and pro-/anti-inflammatory activity of TC with or without visible light irradiation (VLI). The radical-scavenging activity of TC and minocycline (MC) was determined by differential scanning calorimetry (DSC). The stoichiometric factor (n) and the rate constant of inhibition and propagation (kinh/kp) were determined. The levels of cyclooxygenase-2 (Cox2), tumor necrosis factor-α (Tnfα) or nitric oxide synthase 2 (Nos2) mRNA in RAW264.7 cells stimulated with lipopolysaccharide (LPS) were investigated using real-time reverse transcriptase-polymerase chain reaction. The n and kinh/kp values for 1 mM TC in 2,2'-azobisisobutyronitrile and benzoyl peroxide systems were 0.1-0.2 and 119-250, respectively, whereas the corresponding values for quercetin (QU) and resveratrol (RE) were 2-4 and 7-15, respectively. In RAW264.7 cells stimulated with LPS, Cox2 and Tnfα mRNA were over-expressed in the presence of TC. MC down-regulated only the expression of Cox2 by about 50% in LPS-stimulated cells. The anti-inflammatory activity determined on the basis of Cox2 inhibition declined in the order QU>RE>MC>TC. Upon application of VLI, only TC down-regulated the expression of LPS-stimulated Cox2 and Tnfα mRNA. After exposure to VLI, TC, but not MC, markedly up-regulated hemoxygenase-1 (Ho-1) expression. TC is a chain-breaking antioxidant with a large kinh Upon activation by VLI, TC may undergo degradation and its degradation products affect pleiotropic mediators such as Cox2, Tnfα and Ho-1. TC may be useful as a local photodynamic therapy for periodontal diseases.

Iron(III)-mediated ATRP systems of n-docosyl acrylate with AIBN and BPO

Well-defined poly(n-docosyl acrylate) (PDA) with narrow molecular weight distribution has been synthesized by atom transfer radical polymerization (ATRP) and reverse ATRP of n-docosyl acrylate (DA) at 80 °C in N,N-dimethylformamide using the carbon tetrabromide/FeCl3/2,2′-bipyridine (bpy) initiation system in the presence of 2,2′-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) as the source of reducing agent. The rates of polymerization for both the systems exhibit first-order kinetics with respect to the monomer, however, peroxide-initiated system shows slow rate of polymerization as compared to the azo-system. The effect of various reaction parameters on number average molecular weight (M n ) and molecular weight distribution (M w/M n ) have been investigated. The resulting PDA that obtained in presence of AIBN and BPO systems has been compared for both the conventional and reverse ATRP. The reverse ATRP initiated by peroxides behaves differently than that of the azo initiators. In reverse ATRP with BPO, the rate of polymerization (R p) has been significantly increased with the increase of BPO resulting higher M n and broader M w/M n . The reverse ATRP of DA did not exhibit living characteristics with BPO system. PDA has been characterized by GPC, FTIR, and NMR spectroscopy.

ChemInform Abstract: Radical Mono- and Dideoxygenations with the Triethylsilane and Benzoyl Peroxide System.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Quantum-chemical study of the mechanism of formation of styrene polymerization centers under initiation by the ferrocene—benzoyl peroxide system

The mechanism of formation of free polystyrene growth radicals and radicals bound to complexes with ferrocene when polymerization was performed in the presence of the ferrocene—benzoyl peroxide initiating system was studied by quantum-chemical calculations with the use of the PRIRODA program and the PBE/3z method. The calculated structure of the charge transfer complex between ferrocene and benzoyl peroxide was in agreement with the experimental data. The calculated heat effects of possible complex decomposition reactions showed that radical formation easily occurred in the presence of the monomer only. The most favorable energetically scheme of the formation of the active centers of the complex-radical polymerization of styrene, including the intermediate formation of the ferrocene—benzoyloxy radical complex, was suggested.

A comparison of a novel benzoyl peroxide system with a combination benzoyl peroxide and clindamycin product: A 2-week split face study of effectiveness and tolerability

A comparison of a novel benzoyl peroxide system with a combination benzoyl peroxide and clindamycin product: A 2-week split face study of effectiveness and tolerability

Novel Unsaturated Polyester Amide Resins Based on Epoxy Resins

Novel unsaturated polyester amide resins (UPEAs) were prepared by the addition reaction of commercially available epoxy resin, namely diglycidyl ether synthesized from bisphenol-A and epichlorohydrin and having the molecular weight 340 with aromatic unsaturated bisamic acids. These UPEAs were characterized by elemental analysis and number average molecular weight determination by nonaqueous conductometric titrations. The curing study of these UPEAs was carried out by using benzoyl peroxide (BPO) as a catalyst and was monitored by using a differential scanning calorimeter (DSC). According to the curing temperature obtained from the DSC thermograms, the glass fiber reinforced composites (i.e., laminates) of these UPEA–BPO systems have been fabricated. The chemical, mechanical, and electrical properties of these glass fiber composites have also been evaluated. The unreinforced cured samples of the UPEA resins were also analyzed by using thermogravimetric analyzer (TGA).

Homogeneous graft copolymerization of acrylonitrile onto high α‐cellulose in a dimethyl acetamide and lithium chloride solvent system

AbstractHomogeneous graft copolymerization of acrylonitrile (AN) monomer onto high α‐cellulose was investigated in a lithium chloride/N,N‐dimethyl acetamide (DMAc/LiCl) solvent system. Benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were used as radical initiators. By varying temperature, time, and monomer concentrations in grafting reactions, the optimum conditions for both initiator systems were fixed. The graft yield for the AN–BPO system was higher than that for the AN–AIBN system. The optimum conditions of reactions were at temperatures of 70 and 60°C with initiator concentrations of 0.4% (0.36 mmol) and 2% (1.24 mmol) for the AN–AIBN and AN–BPO systems, respectively, at a monomer concentration of 5% (14.1 mmol) solution. The number of grafts per cellulose chain was in the range from 2.2 to 1.1 for AN–BPO and 0.5 to 2.1 for the AN–AIBN system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 630–637, 2003

Kinetic evaluation of reactivity of bisphenol A derivatives as radical scavengers for methacrylate polymerization

The reactivity of bisphenol A (BPA), diethylstilbestrol (DEST) 2,2′-biphenol (22′BP), 4,4′-biphenol (44′BP) and hydroquinone (HQ) as radical scavengers was examined in 2,2′-azobisisobutyronitrile (AIBN)- and benzoyl peroxide (BPO)-induced methyl methacrylate (MMA) polymerization with respect to kinetic considerations. The initial rate of polymerization (IRP) was found to decrease in the order: 44′BP>BPA, DEST>22′BP⪢HQ, while the stoichiometric factor ( n) of free radicals trapped by phenolic moiety decreased in the order: 44′BP (2.3)>HQ (2.0)>BPA, DEST (1.8)⪢22′BP (0.8). It was found that BPA was a more highly efficient inhibitor than HQ and that HQ acts as a retarder at higher concentrations in the BPO system. The high activity of BPA indicated that BPA is probably oxidized by a radical interaction in the dental resin system.

Action of eugenol as a retarder against polymerization of methyl methacrylate by benzoyl peroxide

This study was undertaken to examine an effect of eugenol on polymerization of methyl methacrylate (MMA) by benzoyl peroxide (BPO) and 2,2′-azobisisobutyronitrile (AIBN) in the presence of eugenol. The induction period and initial rate of polymerization (IRP) were determined from polymerization curves of MMA using differential scanning calorimetry (DSC). The induction period increased with increasing concentration of eugenol in both BPO and AIBN systems. The IRP decreased as the concentration of eugenol in both BPO and AIBN systems. The IRP decreased as the concentration of eugenol increased. Its decreasing rate in the BPO system was higher than that in the AIBN system. In the BPO system, the IRP was reduced to zero at 0.5 mol% of eugenol. Eugenol in the BPO system was an efficient retarder, although the decrease in IRP was relatively small, below 0.05 mol%. Eugenol was an inhibitor even at high concentration in the AIBN system. The suppressible effect of eugenol appears to be due to the interaction between free radicals from BPO and eugenol.

Radical mono- and dideoxygenations with the triethylsilane + benzoyl peroxide system.

Thionocarbonates and xanthates of primary and secondary alcohols, as well as dixanthates of vic-diols can easily be deoxygenated to the corresponding hydrocarbons or olefins with triethylsilane and benzoyl peroxide in high-yielding radical reactions.

Effects of ligands on the “living” radical polymerization initiated by the aged Cr2+ plus benzoyl peroxide system

AbstractThe “living” radical polymerization of methyl methacrylate with the aged Cr2+ plus benzoyl peroxide (BPO) system in the presence of various amines as ligand has been studied in N,N′‐dimethylformamide. Aliphatic amines such as ethylenediamine diminished the rate of polymerization, while dipyridyl (dipy) and o‐phenanthroline (phen) accelerated the polymerization rate as follows: phen > dipy > pyridine ≃ none. Specifically, the rate of polymerization in the presence of phen had a maximum value at [phen]/[Cr2+] = 0.5. The retardation of polymerization by aliphatic amines was explained by the interaction of BPO with free and coordinated amines. The latter result may support the mechanism involving the complexed radical proposed for the living radical polymerization with the aged Cr2+ + BPO system. In the presence of phen the effects of aging period and aging temperature as well as polymerization temperature were studied and the nature of complexed radicals is discussed.

Covalent binding of carbon tetrachloride metabolites to liver nuclear DNA, proteins, and lipids

14 C from 14 CCl 4 irreversibly binds in vivo to liver DNA from strain A J mice and Sprague-Dawley rats. Binding of 14 CCl 4 to DNA was also observed in vitro in incubation mixtures containing microsomes and a NADPH-generating system as well as in tissue slices. Chemically induced ·CCl 3 (CCl 4 + benzoyl peroxide system) intensively binds to DNA. Liver nuclear proteins also irreversibly bind CCl 4 metabolites. Nuclear protein fractionation studies revealed that deoxyribonucleoproteins, acidic proteins, histones, and residual proteins are the favorite targets of metabolite interaction. Nuclear sap proteins are less intensively labeled. Nuclear lipids were markedly labeled by CCl 4 reactive metabolites. Most of the label is in the phospholipid fraction and diphosphatidylglycerol is most intensively labeled; phosphatidylethanolamine, phosphatidylcholine, lysophosphatidylcholine, and sphingomyeline are also labeled by metabolites. The interaction of ·CCl 3 with DNA and nuclear proteins could be relevant to CCl 4-induced liver tumors and hepatotoxic effects.

An ESR and spin-trap study of the interaction of acyl peroxides with tetrahalomethanes in the presence of iron compounds

1. ESR and spin-trap methods have been used to show that the interaction of Fe(CO)5 or Fe(C5H5)2 with peroxides leads to the formation of acyloxy radicals. Carried out in CCl4, these reactions lead to the formation of both acyloxy and.CC13 radicals. Initiated by the Fe(CO)5 or Fe(C5H5)2+benzoyl peroxide systems, the reaction of BrCCl3 with α-olefins lead to the formation of.CCl3 radicals and adducts of these radicals with the olefin: CCl3CH2.CHR1, where R1=C4H9, C6H13. Initiated by the iron compound + acyl peroxide system, tetrahalomethane addition to olefins proceeds through a radical chain mechanism, chain propagation being through the.CCl3 radicals. 2. Spin adducts of α-phenyl-N-tert-butylnitron with acyloxy and.CCl3 radicals, and 2-methyl-2-nitrosopropane with.CCl3 and CCl3CH2CHR (R is an alkyl) radicals, have been identified.

Radiation-induced polymerization. I. A pyrotechnic binder

In the past, binder systems had to be limited to systems where the catalytically initiated polymerization exotherm was low. With radiation-initiated polymerization, this is not a problem, and the number of monomers which can now be investigated is unlimited. Based upon the styrene–benzoyl peroxide system, addition of peroxide sensitizers significantly decrease the radiation dose required for 100% conversion.