An E.S.R. study of the oxidation of some malonic and other acids by hydroxyl radicals

1981 ◽  
Vol 34 (2) ◽  
pp. 335 ◽  
Author(s):  
FR Hewgill ◽  
GM Proudfoot
Keyword(s):  
Hydroxyl Radicals ◽  
Ethylenediaminetetraacetic Acid ◽  
Flow System ◽  
Dicarboxylic Acids ◽  
Aliphatic Acids ◽  
Ph Values ◽  
Branched Chain

A series of terminal dicarboxylic acids, malonic acids and branched-chain aliphatic acids on oxidation with TiC13/H2O2 in a flow system give rise to e.s.r. spectra arising from mixtures of radicals. In most cases the dominant radical is that formed by abstraction of hydrogen from the β-carbon. Malonic acids complex with titanium(III) ions sufficiently strongly to be examined at elevated pH values without the need for added ethylenediaminetetraacetic acid.

Branched Chain Aliphatic Acids. Isomyristic, Isopalmitic and Isostearic Acids

1933 ◽  
Vol 55 (8) ◽  
pp. 3368-3372 ◽  
Author(s):  
Charles R. Fordyce ◽  
John R. Johnson
Keyword(s):  
Aliphatic Acids ◽  
Branched Chain

scholarly journals III. Peroxisomal β-oxidation, PPARα, and steatohepatitis

2001 ◽  
Vol 281 (6) ◽  
pp. G1333-G1339 ◽  
Author(s):  
Janardan K. Reddy
Keyword(s):  
Fatty Acids ◽  
Dicarboxylic Acids ◽  
Fatty Acyl ◽  
Branched Chain Fatty Acids ◽  
Oxidation Chain ◽  
Branched Chain ◽  
Cytochrome P 450 ◽  
Oxidation System ◽  
Long Chain ◽  
Chain Fatty Acids

Peroxisomes are involved in the β-oxidation chain shortening of long-chain and very-long-chain fatty acyl-CoAs, long-chain dicarboxylyl-CoAs, the CoA esters of eicosanoids, 2-methyl-branched fatty acyl-CoAs, and the CoA esters of the bile acid intermediates, and in the process, they generate H2O2. There are two complete sets of β-oxidation enzymes present in peroxisomes, with each set consisting of three distinct enzymes. The classic PPARα-regulated and inducible set participates in the β-oxidation of straight-chain fatty acids, whereas the second noninducible set acts on branched-chain fatty acids. Long-chain and very-long-chain fatty acids are also metabolized by the cytochrome P-450 CYP4A ω-oxidation system to dicarboxylic acids that serve as substrates for peroxisomal β-oxidation. Evidence derived from mouse models of PPARα and peroxisomal β-oxidation deficiency highlights the critical importance of the defects in PPARα-inducible β-oxidation in energy metabolism and in the development of steatohepatitis.

scholarly journals Royal Jelly Aliphatic Acids Contribute to Antimicrobial Activity of Honey

2018 ◽  
Vol 62 (1) ◽  
pp. 111-123 ◽  
Author(s):  
Walerij Isidorow ◽  
Stanisław Witkowski ◽  
Piotr Iwaniuk ◽  
Monika Zambrzycka ◽  
Izabela Swiecicka
Keyword(s):  
Fatty Acids ◽  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Royal Jelly ◽  
Dicarboxylic Acids ◽  
Antibacterial Action ◽  
Larval Food ◽  
Nutrient Media ◽  
Minimal Inhibitory Concentrations ◽  
Aliphatic Acids

Abstract Honey is valued for its therapeutic qualities which are attributed among others to its antibacterial multifactorial properties. However, all the factors that influence these properties have not been identified. The present study is focused on the antibacterial action of fatty acids originating from royal jelly, the larval food of honeybees. Aliphatic C8-C12 acids characteristic of this bee product had previously been identified in more than fifty different samples of honey originating from seven countries and in eleven samples of Polish herbhoney. Experiments were performed to ascertain the influence of acidity on the antimicrobial activity of the acids. In acidic nutrient media all tested aliphatic hydroxyacids and unsaturated dicarboxylic acids demonstrated antibacterial action against different microbes with minimal inhibitory concentrations between 0.048 and 3.125 mM. Our results confirm that part of the antibacterial activity of honey contributes to these compounds of bee origin.

Determination of photonic efficiency and quantum yield of formaldehyde formation in the presence of various TiO2 photocatalysts

2001 ◽  
Vol 44 (5) ◽  
pp. 279-286 ◽  
Author(s):  
C. Wang ◽  
D.W. Bahnemann ◽  
J.K. Dohrmann
Keyword(s):  
Quantum Yield ◽  
Hydroxyl Radicals ◽  
Critical Concentration ◽  
Photon Flux ◽  
Tio2 Photocatalysts ◽  
Ph Values ◽  
Optimum Ph ◽  
Photonic Efficiency ◽  
True Quantum

Illumination of aqueous TiO2 suspentions yields hydroxyl radicals, which can be trapped by methanol producing formaldehyde (HCHO). In this work, the photonic efficiency and quantum yield of HCHO formation in colloidal TiO2 solutions and, P25 and UV 100 suspensions have been determined. Differences in photocatalytic activity of the three photocatalysts have been found and are discussed. The photonic efficiency of HCHO formation in the presence of P25 and UV 100 depends on the concentration of TiO2 and the pH. The critical concentration is 2.5 g/L. Below this, the photonic efficiency with P 25 is higher than with UV 100, and vice versa. Optimum pH values for P25 and UV 100 giving the maximum photonic efficiency are 7.7 and 10.4, respectively. Compared to P25 and UV 100, the true quantum yield of HCHO formation in colloidal TiO2 solution varies a little with pH and virtually does not change with the amount of loading of TiO2. The true quantum yield varies as the inverse square root of light intensity. The quantum yield increases from 0.02 to 0.08 when the absorbed photon flux decreases from 8.1 × 10-7 Ein/L s to 4.9 × 10-8 Ein/L s. A simple model is presented to explain the experimental observation.

Isothermal interpretations of oscillatory ignition during hydrogen oxidation in an open system. I. Analytical predictions and experimental measurements of periodicity

1986 ◽  
Vol 405 (1828) ◽  
pp. 117-128 ◽  
Keyword(s):  
Flow System ◽  
Hydrogen Oxidation ◽  
Mass Conservation ◽  
Stationary States ◽  
Third Body ◽  
Chain Reactions ◽  
Sequence Of Events ◽  
Oxidation Of Hydrogen ◽  
Branched Chain ◽  
Supercritical Reaction

The oxidation of hydrogen under well stirred, flowing conditions is the natural prototype of branched-chain reactions in open, gaseous systems. Experimentally, it exhibits the classical forms for the ( p - T a ) first and second ignition limits in the flow system. The constant reactant supply ensures that stationary states exist at subcritical conditions whereas the supercritical reaction is a repetitive, oscillatory sequence of events. In a linked pair of papers, we investigate isothermal criticality at the second limit in terms of changing nature of the singularities for the mass conservation equations and derive kinetic relationships that explain the oscillatory features. In this paper the origins of oscillatory ignition are traced analytically to chain-branching via H atoms coupled to the changing third-body efficiency in the elementary process H + O 2 + M → HO 2 + M, when water formed during ignition is displaced by the inflow of fresh hydrogen and oxygen. Analytical predictions are made of the periods between successive ignitions and of the conditions at which oscillatory reaction is transformed to a stationary state. A composition limit for the existence of oscillatory ignition in the (lean) mixture H 2 + 15O 2 + 14N 2 is located experimentally and explained in terms of the analytical inter­pretations presented here.

Electron paramagnetic resonance spectroscopic study of nitroxide radicals formed from oximes

1969 ◽  
Vol 47 (12) ◽  
pp. 2227-2236 ◽  
Author(s):  
P. Smith ◽  
W. M. Fox
Keyword(s):  
Hydroxyl Radicals ◽  
Continuous Flow ◽  
Flow System ◽  
Functional Structure ◽  
Methyl Radicals ◽  
Paramagnetic Resonance ◽  
A Value ◽  
Butanedione Monoxime ◽  
Structure Formula ◽  
Electron Paramagnetic

The addition of hydroxyl radicals to each of the oximes, acetaldoxime, acetoxime, and 2,3-butanedione monoxime, has been studied by mixing titanous chloride, hydrogen peroxide, and the oxime in an aqueous continuous-flow system. In each case a β-hydroxy nitroxide (functional structure [Formula: see text] is formed. In confirmation of these results, amino and hydroxymethyl radicals were added to the oximes using similar procedures to give in each case the radicals of functional structure [Formula: see text] and [Formula: see text], respectively. Attempts to add methyl radicals, prepared by the reaction between titanous chloride and t-butyl hydroperoxide, to these oximes gave no observable products save the methyl radicals. However, use of titanous chloride and peracetic acid gave results consistent with the addition of hydroxyl radicals. The addition of hydroxyl radicals to the oxime-O-methyl ethers of acetaldehyde and acetone gave radicals of functional structure [Formula: see text][Formula: see text] which have not previously been identified unambiguously. On the assumption that |QN| = |QHNH| = 23 G in all these radicals, ρNπ has been calculated and used to obtain a value for [Formula: see text] of ca. 11 G which is within the range of other estimates in the literature.

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