Competitive Scavenging Research Articles

Comparison of relative antioxidant activities of British medicinal plant species in vitro

We have determined the relative levels of endogenous antioxidant activity in a range of British medicinal plant species (representative of a variety of plant families, selected on the basis of their widespread use in traditional herbal medicine), via competitive scavenging of the ABTS + or O 2 − radicals in vitro. A number of plant species with appreciable levels (i.e. greater than or comparable with the activity in corresponding extracts of Ginkgo biloba or Panax ginseng, as recognised phytological sources of antioxidant activity) of antioxidant activity against the ABTS + radical were identified as potentially novel sources of free radical scavenging compounds; however none of these extracts showed measurable antioxidant activity when assayed against the O 2 − radical. It, therefore, follows that any comparative determination of antioxidant activity should clearly define the radical species and assay method employed. For those extracts showing activity against the ABTS + radical, in general, it was not possible to predict the potential antioxidant capacity of a given plant species (or the most active part of the plant) on a taxonomical basis, or from its use in traditional or modern medicine. In the longer term further characterisation of the active compounds from plant species with appreciable antioxidant activity identified in the present investigation may prove of value for treatment of disorders such as Alzheimer's disease, in which free radical induced tissue damage has been implicated.

The Effect of α-Tocopherol on the Nitration of γ-Tocopherol by Peroxynitrite

It has been proposed (S. Christenet al. Proc. Natl. Acad. Sci. USA94, 3217–3222, 1997) that although α-tocopherol (α-TH) is an efficient antioxidant, the presence of γ-tocopherol (γ-TH) may be required to scavenge peroxynitrite-derived reactive nitrogen species. To investigate the reactions between α-TH, γ-TH, and peroxynitrite, endogenous levels of both α-TH and γ-TH were monitored when low-density lipoprotein was oxidized in the presence of the peroxynitrite generator 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium (SIN-1). SIN-1 oxidized α-TH while γ-TH levels remained constant. The sparing of γ-TH was also demonstrated when 1,2-dilauroyl-sn-glycero-3-phosphocholine liposomes containing α-TH and γ-TH were incubated with either SIN-1 or peroxynitrite. Our data show that α-TH inhibits peroxynitrite-mediated γ-TH nitration, i.e., 5-NO2-γ-tocopherol formation. The rate constants for the reactions between both α-TH and γ-TH with peroxynitrite suggest that the sparing of γ-TH by α-TH does not occur by competitive scavenging, but may be due to the formation of a transient γ-TH intermediate. Nitration of γ-TH becomes significant only after α-TH levels have been depleted. We conclude α-TH alone is sufficient to remove any peroxynitrite-derived reactive nitrogen species, as the presence of α-TH attenuates nitration of both γ-TH and tyrosine. The present results also indicate that a bolus addition of peroxynitrite or SIN-1 to liposomes containing γ-TH forms 5-NO2-γ-tocopherol in similar yields. This is in contrast to their reaction profile with tyrosine in aqueous solution. Under these conditions, SIN-1 does not form nitrotyrosine at detectable yields.

A role for scavenger receptors in phagocytosis of protein-coated particles in rainbow trout head kidney macrophages

In macrophages of higher vertebrates, Fc receptors and receptors for complement and other serum factors, are generally known to enhance the phagocytic process. In lower vertebrates like salmonid fishes, none of these or other phagocytic receptors have been thoroughly characterized. The purpose of this study was to elucidate to what extent these and other receptors are involved in the process of phagocytosis in rainbow trout ( Oncorhynchus mykiss) head kidney macrophages. We used tosyl activated, paramagnetic dynabeads (2.8 μm in diameter), specifically coated with 12;I labeled Atlantic salmon ( Salmo salar) IgM or bovine serum albumin (BSA) as phagocytic probes. The effect of complement opsonization was also investigated by incubating the beads in serum. Our results indicate that neither the Fc- nor the complement-receptor(s) were important for phagocytosis of these beads. Our data support the idea that scavenger receptors are involved in phagocytosis in rainbow trout head kidney macrophages, as the use of a competitive scavenger receptor ligand extensively decreased degradation of the labeled protein coat on the beads.

Effect of Purine Nucleoside Phosphates on OH-Radical Generation by Reaction of Fe2+ With Oxygen

The influence of various purine nucleotides, nucleosides and nucleoside phosphates on the generation of OH-radicals by the reaction of Fe2+ with oxygen was investigated. Coumarin-3-carboxylic acid was used as a fluorescent detector of OH.. Nucleoside triphosphates caused the enhancement of OH. production due to chelation of ferrous ion by the phosphate moiety. About 30% of produced OH. are intramolecularly scavenged by the nucleoside moiety of the chelator molecule. Nucleoside diphosphates cause a slight enhancement of OH. yield. Nucleotides, nucleosides and nucleoside monophosphates decrease the OH. production. Rate constants of reaction between OH. and nucleoside derivatives were determined from the competitive scavenging of OH radicals, produced by oxidation of Fe(2+)-EDTA complex. Derivatives of guanosine and xanthine are more efficient scavengers in comparison to adenine and inosine. Phosphate groups do not affect the constant of reaction of nucleoside with OH.. Our results suggest that the yield of OH. in the presence of the nucleotide derivatives is determined by chelation of ferrous with polyphosphates and preferential OH. scavenging by the organic portion of molecule. We propose that the generation of active oxygen intermediates in the reaction between nucleoside triphosphate complexes of iron and molecular oxygen is involved in iron-related cellular injury.

Reactivity of propylimidazole platinum complexes in water-methanol systems

The radiation reduction of platinum complexes Pt(PIA) 2Cl 4 and Pt(PIA) 2Cl 2, in methanol and aqueous methanol solutions have been examined. The intermediate oxidation states Pt(III) and Pt(I) have been identified by ESR in solid state. The yields of Pt(I) depend on the kind of halide ions in the complex. The corresponding rate constants of reactions between the complexes and e solv − have been determined by pulse radiolysis. The attempts to determine the rate constants of scavenging of oxidizing radicals by complexes using pNDA as the competitive scavenger were unsuccessful because of the low corresponding rate constants and the secondary processes of NDA incorporation into the complexes.

In Situ Radiolysis Time-Resolved ESR Studies of Spin Trapping by DMPO: Reevaluation of Hydroxyl Radical and Hydrated Electron Trapping Rates and Spin Adduct Yields

The second-order rate constants for the reaction of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) with radiolytically produced hydroxyl radicals and hydrated electrons have been measured in aqueous solution by direct observation of spin adduct initial yield using time-resolved electron spin resonance. The rate constants are 2.8 × 109 mol-1 dm3 s-1 for the DMPO−hydroxyl radical addition reaction and 3.2 × 109 mol-1 dm3 s-1 for the reaction of DMPO and hydrated electron, using sodium formate and chloroacetic acid as competitive scavengers of the hydroxyl radical and hydrated electron, respectively. The hydrated electron−DMPO competition study determined the fraction of DMPO−H produced directly from radiolytically produced hydrogen atoms as 0.082 of the total DMPO−H yield, indicating that approximately half of the hydrogen atoms react with DMPO to produce non-aminoxyl products. The fraction of the total hydroxyl radical yield leading to DMPO−OH spin adduct was determined to be 0.94, using the bleach of 2,2,6,6-tet...

Ferritin Stimulation of Hydroxyl Radical Production by Rat Liver Nuclei

Iron mobilized from ferritin has been shown to catalyze production of potent reactive oxygen intermediates. Experiments were carried out to evaluate the ability of ferritin to catalyze nuclear generation of hydroxyl radical in the presence of either NADPH or NADH. In the absence of redox cycling agents, ferritin did not catalyze nuclear oxidation of hydroxyl radical scavenging agents (2-keto-4-thiomethylbutyric acid, dimethylsulfoxide, ethanol) even if EDTA was added to chelate any released iron. The addition of menadione or paraquat resulted in a ferritin-dependent oxidation of chemical scavengers; menadione promoted the catalysis by ferritin with either NADPH or NADH, whereas paraquat was much more reactive with NADPH as the nuclear reductant. The presence of an externally added iron chelator was required for elevated rates of scavenger oxidation, with EDTA and DTPA being more reactive than ATP or citrate and desferrioxamine being inhibitory. The ferritin-catalyzed hydroxyl radical scavenger oxidation was sensitive to superoxide dismutase, catalase, and competitive scavengers. In the absence or presence of ferritin, rates of NADPH- or NADH-dependent H 2O 2 production were low; menadione increased H 2O 2 production with both NADPH and NADH, whereas paraquat was mostly effective with NADPH. Depending on the nature of the added chelating agent (e.g., EDTA, ATP) and the reductant, rates of nuclear production of ·OH in the presence of redox cycling agent plus ferritin were 10 to 70% as high as rates found with redox cycling agent plus ferric-chelate (e.g., ferric-EDTA, ferric-ATP). Since reactive oxygen intermediates such as the hydroxyl radical can alter the structural integrity of the nucleus and interact with DNA, the ability of ferritin to promote nuclear generation of hydroxyl radical may play a role in the toxicity associated with iron as well as redox cycling agents.

Nitroxide-mediated protection against X-ray-and neocarzinostatin-induced DNA damage

The stable free radical Tempol (4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy) has been shown to protect against X-ray-unduced cytotoxicity and hydrogen peroxide- or xanthine oxidase-induced cytotoxicity and mutagenicity. The ability of Tempol to protect against X-ray- or neocarzinostatin (NCS)-induced mutagenicity or DNA double-strand breaks (dsb) was studied in Chinese hamster cells. Tempol (50 mM) provided a protection factor of 2.7 against X-ray-induced mutagenicity in Chinese hamster ovary (CHO) AS52 cells, with a protection factor against cytotoxicity of 3.5. Using the field inversion gel electrophoresis technique of measuring DNA dsb, 50 mM Tempol provides a threefold reduction in DNA damage at an X-ray dose of 40 Gy. For NCS-induced damage, Tempol increased survival from 9% to 80% at 60 ng/mL NCS and reduced mutation induction by a factor of approximately 3. DNA dsb were reduced by a factor of approximately 7 at 500 ng/mL NCS. Tempol is representative of a class of stable nitroxide free radical compounds that have superoxide dismutase-mimetic activity, can oxidize metal ions such as ferrous iron that are complexed to DNA, and may also detoxify radiation-induced organoperoxide radicals by competitive scavenging. The NCS chromophore is reduced by sulfhydryls to an active form. Electron spin resonance (ESR) spectroscopy shows that 2-mercaptoethanol-activated NCS reacts with Tempol 3.5 times faster than does unactivated NCS. Thus, Tempol appears to inactivate the NCS chromophore before a substantial amount of DNA damage occurs.

Reactivity of the Transient UV-Band Produced in Irradiated Liquid Carbon Tetrachloride with Various Alcohols

Abstract The reactivities of the transient UV-band with a peak at 330 nm produced in irradiated liquid carbon tetrachloride with various alcohols have been measured using the absolute technique of pulse radiolysis. The obtained bimolecular rate constants have been compared with those previously determined for the reaction of chlorine atoms with various alcohols using the competitive scavenging method. The values of reaction rate constants of the UV-band are nearly twice those of chlorine atoms. Similar kinetic isotope effects were observed for deuterated methanol and 2-methyl-2-propanol. However, the dependence on the structure of the alcohols, which is characteristic for hydrogen abstraction from alcohols by chlorine atoms, has not been established by the reaction of the UV-band. These results strongly suggest that the assignment of the UV-band to chlorine atoms is not plausible, and instead, support the assignment to parent cations.

Synergistic interactions between nadph-cytochrome P-450 reductase, paraquat, and iron in the generation of active oxygen radicals

The toxicity associated with paraquat is believed to involve the generation of active oxygen radicals and the production of oxidative stress. Paraquat can be reduced by NADPH-cytochrome P-450 reductase to the paraquat radical; this results in consumption of NADPH. A variety of ferric complexes, including ferric-ATP, -citrate, -EDTA, ferric diethylenetriamine pentaacetic acid and ferric ammonium sulfate, produced a synergistic increase in the paraquat-mediated oxidation of NADPH. This synergism could be observed with very low concentrations of iron, e.g. 0.25 μM ferric-ATP. Very low rates of hydroxyl radical were generated by the reductase with paraquat alone, or with ferric-citrate or -ATP or ferric ammonium sulfate in the absence of paraquat; however, synergistic increases in the rate of hydroxyl radical generation occurred when these ferric complexes were added together with paraquat. Ferric-EDTA and -DTPA catalyzed some production of hydroxyl radicals, which was also synergistically elevated in the presence of paraquat. Ferric desferrioxamine was essentially inert in the absence or presence of paraquat. This enhancement of hydroxyl radical generation was sensitive to catalase and competitive scavengers but not to superoxide dismutase. The interaction of paraquat with NADPH-cytochrome P-450 reductase and ferric complexes resulted in an increase in oxygen radical generation, and various ferric complexes increased the catalytic effectiveness and potentiated significantly the toxicity of paraquat via this synergistic increase in oxygen radical generation by the reductase.

Detection of photolytically produced hydroxyl radicals by reaction with 2,2,2-trichloroethanol

A screening technique for the detection of the hydroxyl radical on photolysis of drugs or other chemicals is described. The technique depends upon scavenging the radical with 2,2,2-trichloroethanol in buffered aqueous solution and determining the liberated chloride ion. The system was validated using sodium nitrite as a model source of photolytically produced hydroxyl radicals. Competition kinetic experiments were performed using glucose, glycine and sulphate ion as competitive scavengers. The drugs metronidazole, phenylephrine and chloroquine diphosphate were examined for hydroxyl radical production on simulated sunlight photolysis, metronidazole caused no chloride liberation from 2,2,2-trichloroethanol on the time scale studied. In the case of chloroquine diphosphate, chloride ion liberated directly from the drug on its photolysis interfered with kinetic evaluation of the results. Chloride ion production from 2,2,2-trichloroethanol induced by phenylephrine was kinetically equivalent to that caused by the hydroxyl radical.

Increased microsomal interaction with iron and oxygen radical generation after chronic acetone treatment

In vivo administration of acetone influences a variety of reactions catalyzed by rat liver microsomes. The effect of chronic treatment with acetone (1% acetone in the water for 10–12 days) on interaction with iron and subsequent oxygen radical generation by liver microsomes was evaluated. Microsomes from the acetone-treated rats displayed rates of H 2O 2 generation, an increase in iron-dependent lipid peroxidation, and enhanced chemiluminescence upon the addition of t-butylhydroperoxide. The ferric EDTA-catalyzed production of formaldehyde from DMSO or of ethylene from 2-keto-4-thiomethylbutyrate was increased 2-fold after acetone treatment. This increase in hydroxyl radical generation was accompanied by a corresponding increase in NADPH utilization and was sensitive to inhibition by catalase and a competitive scavenger, ethanol, but not to superoxide dismutase. In vitro addition of acetone to microsomes had no effect on oxygen radical generation. Associated with the chronic acetone treatment was a 2-fold increase in the microsomal content of cytochrome P-450 and in the activity of NADPH-cytochrome- P-450 reductase. It appears that increased oxygen radical generation by microsomes after chronic acetone treatment reflects the increase in the major enzyme components which comprise the mixed-function oxidase system.

Radiation damage to ?X174 DNA and biological effects

Dilute aqueous solutions of biologically active DNA can serve as a simplified model system of the cell. As a biological endpoint the survival of the DNA (after transfection to E. coli spheroplasts) is used. Damage in the DNA, irradiated in water with gamma rays, can be ascribed to reactions with primary waterradicals. By introducing additives in such solutions, which will scavenge the primary waterradicals, competition between a scavenger and DNA for such radicals can be studied. Comparison of different additives makes it possible to decide whether a compound behaves like a simple scavenger, radiosensitizer or like a radioprotector. In this context work has been done with the electron-affinic radiosensitizers metronidazole, misonidazole and nifuroxime. We have found that these wellknown cellular sensitizers do not enhance the inactivation of biologically active DNA. They act as simple competitive scavenger for waterradicals. However, if besides a sensitizer a trace of a metalloporphyrin containing compound (e.g. cyt. c) is present during irradiation an enhanced DNA inactivation, which can be interpreted as sensitization, is observed. Without sensitizer metalloporphyrins induce an enhanced protection of DNA. Apart from these effects the consequences of both chemical-(sulphydryl) and enzymatic-(excision; recombination) repair has been studied. It has been found that sulphydryl compounds are able to react with DNA radicals, modifying the radiation damage in such a way that e.g. breaks are prevented. Further in double-stranded DNA a considerable amount of OH and also H radical damage appeared to be reparable by the excision-repair mechanism. However, post-replication repair had only very small or no effect on the amount of damage.

Kinetics and mechanism of the gas-phase pyrolysis of hexafluorodisilane in the presence of iodine and some reactions of silicon difluoride

The gas-phase thermal decomposition of Si2F6 in the presence of I2 has been found to follow first-order kinetics with the formation of SiF4, SiF2I2 and SiF3I. The reactions appear to be homogeneous and consistent with the mechanism: Si2F6→ SiF2+ SiF4(slow)(1), SiF2+ I2→ SiF2I2(fast).(2) SiF3I is a minor product and its mechanism of formation is uncertain. Rate measurements over the temperature range 603–652 K fit the Arrhenius equation: log (k1/s–1)=(12.41 ± 0.24)–(193.5 ± 2.9 kJ mol–1)/RT ln 10. In competitive scavenging reactions at 630 K, SiF2 is found to react with I2 3.6 times faster than with O2 and 17 times faster than HI. The reaction of SiF2 with I2 is also at least a factor of 102 faster than with HBr or benzene and greater than 104 times faster than with SiF4. The absence of an I˙ atom displacement process is consistent with D(F3Si—SiF3) 337 kJ mol–1, which leads to the value ΔH⊖f(Si2F6)⩽–2337 kJ mol–1.

Ethylene production from α-keto-4-thiomethylbutyric acid by isolated rat liver cells, suspension medium, and perfusates in the absence and presence of iron

Experiments were carried out to evaluate the production of hydroxyl radical-like species by intact rat liver cells by assaying for the production of ethylene from α-keto-4-thiomethylbutyric acid in the absence and presence of added iron. In the absence of iron, a low rate of ethylene production, which was not sensitive to superoxide dismutase, catalase, or competitive scavengers was observed. Ethylene was produced when KMBA was incubated with perfusates of rat liver or the suspension medium obtained after incubating liver cells for varying periods of time, followed by removal of the liver cells. Boiling the perfusate or suspension medium had no effect on ethylene production. This ethylene production does not appear to reflect an oxygen radical-mediated event. The addition of ferric-EDTA, but not ferric-desferrioxamine, increased ethylene production by the hepatocyte suspensions in a reaction sensitive to inhibition by catalase, ascorbate oxidase, and competitive scavengers, but not superoxide dismutase. The sensitivity to externally added catalase and ascorbate oxidase suggested that the ethylene production reflected an extracellular oxygen radical generating system. Ferric alone and several ferric chelates, for example, ferric-ATP, ADP, AMP, histidine, and citrate stimulated ethylene production using perfusates of liver or suspension medium after removal of the hepatocytes. The sensitivity of the added iron system to ascorbate oxidase suggested that during perfusion or incubation of liver cells, efflux of ascorbate occurs, follwed by reduction of the iron and subsequently, extracellular production of oxygen radicals. Indeed, a strong correlation was observed between rates of ethylene production in the presence of iron and levels of ascorbate in the perfusates. Thus, the use of KMBA plus iron is not suitable to detect intracellular production of hydroxyl radical-like species in cells such as hepatocytes, which leak ascorbate.

Concentration-dependent inactivation of superoxide dismutase

The inactivation yield of superoxide dismutase (superoxide: superoxide oxidoreductase, EC 1.15.1.1) from bovine erythrocytes, when Co 60-γ-irradiated in air, N 2 or N 2O-saturated solutions, increases exponentially with the initial enzyme concentration. In aerated solutions at ⪯10 μM, the inactivation process continues in a concentration-dependent manner in the subsequent 72 h. This post-irradiation effect is inhibited by catalase. Above 10 μM, radiation-induced inactivation of the enzyme is partially reversed in a concentration-dependent manner and is not affected by catalase. In aerated and N 2O-saturated solutions, competitive scavenging of radiation chemical species by catalase and EDTA in combination reduces the inactivation yield by 80%; the residual yield remains dependent on enzyme concentration. Radiation-induced loss of copper and zinc initially exhibits a linear dose-response relationship and is less severe than the drop in enzyme activity.

Kinetic Investigations of the Autoxidation of Adrenalin

Generation rates of superoxide anions (O2-) by autoxidizing adrenalin at pH 9.5 were determined in solutions containing either superoxide dismutase (0.85 M-1 S-1) or hydroxylamine (0.0185 M-1 S-1) as competitive scavengers. The rate constants of O2- with adrenalin and hydroxylamine were calculated for neutral and alkaline solutions. The respective values were for adrenalin: 5.6 X 10(4) M-1 S-1, pH 7.8; 7.0 X 10(3) M-1 S-1, pH 9.5--and for hydroxylamine 5.9 X 10(4) M-1 S-1, pH 7.8; 3.4 X 10(4) M-1 S-1, pH 9.5. The effects of various competitors and O2- sources on the rate constants were compared.

REACTIONS OF O‐2, H2O2 AND OTHER OXIDANTS WITH SULFHYDRYL ENZYMES‡

Abstract— The inactivation of a number of sulfhydryl enzymes by H2O2. OH and O‐2 is discussed. and the efficiencies of inactivation for the free radicals are compared with those of halide radicals. The enzymes with essential acyl‐binding SH groups (papain and GAPDH) exhibit a higher sensitivity to inactivation by O‐2 and H2O2 than those with “unactivated” SH groups (LDH and ADH). The sulfenic acid derivatives from the reactions of papain and GAPDH with H2O2 are repairable by RSH molecules, the rates of repair depending on the nature of the R group.Comparisons of rate constants show that competitive scavenging by RSH must be a very important mechanism for the protection of sensitive SH‐containing proteins against OH, and for papain in oxygen‐free solutions the efficiency of this protection increased in the order GSH < PenSH < CysSH < dithiothreitol. On the other hand, catalase and superoxide dismutase are more effective than RSH compounds in rendering protection against H2O2 and O‐2. In fact in oxygen‐containing systems the effects of RSH are highly complex, because the OH‐ and/or O‐2‐initiated chain oxidation of these molecules produces reactive species, which may inactivate essential SH groups. Experiments with papain showed that the yields and nature of the RSH‐derived species depended on the structure of the R group. Also, very large yields of papain Cys25SSR were produced from the reactions of the radicals and H2O2. In effect, it is apparent that under certain conditions the oxidation of “activated” SH groups of important target molecules could become coupled to the OH or O‐2 ‐initiated oxidation of RSH molecules. This should be taken into account in assessing the overall effectiveness of RSH compounds as cellular protectors.

A probe for homolytic reactions in solution. Part VIII. An electron spin resonance study of the rates of fragmentation and spin trapping of t-butoxycarbonyl radicals and acyl radicals

From a study of the competition between spin trapping and decarboxylation, the rate constant for addition of the t-butoxycarbonyl radical to 2-methyl-2-nitrosopropane (nitrosobutane) has been determined to be 1·1 × 106 I mol–1s–1 at 40° in di-t-butyl peroxide solvent. The rate constant in benzene must be very similar. Competitive scavenging and decarbonylation of a series of acyl radicals (RĊO) shows that the ease of loss of carbon monoxide increases along the series R = Me < Pri < adamantyl < But < PhCH2. An absolute rate constant (3·9 × 103s–1 at 40°) for the decarbonylation of PriĊO is obtained by assuming that this radical adds to nitrosobutane at the same rate as t-butoxycarbonyl. This rate constant is considerably smaller than that obtained previously in the gas phase and a possible source of error in the gas-phase value is identified. The formation of t-butoxy t-butyl nitroxide by addition of t-butoxyl radicals to nitrosobutane is reversible at ambient temperatures. Fragmentation of this nitroxide to give t-butoxyl radicals occurs with a rate constant of ca. 0·14 s–1 at 40°, whilst fragmentation with loss of t-butyl radicals is shown to occur by N–C, and not O–C, fission with a rate constant of ca. 10–3 s–1 at 40°.

Kinetic study of radical production in the thermal decomposition of benzoyl peroxide by electron spin resonance spin trapping (spin counting). Rate (and substituent effect on the rate) of spin trapping by competitive scavenging of benzoyloxy radicals with galvinoxyl

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic study of radical production in the thermal decomposition of benzoyl peroxide by electron spin resonance spin trapping (spin counting). Rate (and substituent effect on the rate) of spin trapping by competitive scavenging of benzoyloxy radicals with galvinoxylEdward G. Janzen, C. Anderson Evans, and Yasutaka NishiCite this: J. Am. Chem. Soc. 1972, 94, 23, 8236–8238Publication Date (Print):November 1, 1972Publication History Published online1 May 2002Published inissue 1 November 1972https://doi.org/10.1021/ja00778a053RIGHTS & PERMISSIONSArticle Views263Altmetric-Citations54LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (381 KB) Get e-Alerts Get e-Alerts