Free radical epoxidation of 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene by hematin and polyunsaturated fatty acid hydroperoxides

1981 ◽  
Vol 103 (22) ◽  
pp. 6744-6746 ◽  
Author(s):  
Thomas A. Dix ◽  
Lawrence J. Marnett
Keyword(s):  
Fatty Acid ◽  
Free Radical ◽  
Polyunsaturated Fatty Acid ◽  
Fatty Acid Hydroperoxides

scholarly journals A Caleosin-Like Protein with Peroxygenase Activity Mediates Aspergillus flavus Development, Aflatoxin Accumulation, and Seed Infection

2015 ◽  
Vol 81 (18) ◽  
pp. 6129-6144 ◽  
Author(s):  
Abdulsamie Hanano ◽  
Ibrahem Almousally ◽  
Mouhnad Shaban ◽  
Elizabeth Blee
Keyword(s):  
Fatty Acid ◽  
Aspergillus Flavus ◽  
Polyunsaturated Fatty Acid ◽  
Calcium Binding ◽  
Antioxidant Activities ◽  
Fungal Growth ◽  
Oxidation Reactions ◽  
Content Type ◽  
Fatty Acid Hydroperoxides

ABSTRACTCaleosins are a small family of calcium-binding proteins endowed with peroxygenase activity in plants. Caleosin-like genes are present in fungi; however, their functions have not been reported yet. In this work, we identify a plant caleosin-like protein inAspergillus flavusthat is highly expressed during the early stages of spore germination. A recombinant purified 32-kDa caleosin-like protein supported peroxygenase activities, including co-oxidation reactions and reduction of polyunsaturated fatty acid hydroperoxides. Deletion of the caleosin gene prevented fungal development. Alternatively, silencing of the gene led to the increased accumulation of endogenous polyunsaturated fatty acid hydroperoxides and antioxidant activities but to a reduction of fungal growth and conidium formation. Two key genes of the aflatoxin biosynthesis pathway,aflRandaflD, were downregulated in the strains in whichA. flavusPXG(AfPXG) was silenced, leading to reduced aflatoxin B1 productionin vitro. Application of caleosin/peroxygenase-derived oxylipins restored the wild-type phenotype in the strains in whichAfPXGwas silenced.PXG-deficientA. flavusstrains were severely compromised in their capacity to infect maize seeds and to produce aflatoxin. Our results uncover a new branch of the fungal oxylipin pathway and may lead to the development of novel targets for controlling fungal disease.

The chemistry of lipid alkoxyl radicals and their role in metal-amplified lipid peroxidation

1995 ◽  
Vol 61 ◽  
pp. 65-72 ◽  
Author(s):  
Lawrence J. Marnett ◽  
Allan L. Wilcox
Keyword(s):  
Lipid Peroxidation ◽  
Steady State ◽  
Fatty Acid ◽  
Hydroxyl Radical ◽  
Metal Complexes ◽  
Polyunsaturated Fatty Acid ◽  
Ring Opening ◽  
Steady State Concentration ◽  
State Concentration ◽  
Fatty Acid Hydroperoxides

Reaction of polyunsaturated fatty acid hydroperoxides with metal complexes generates lipid alkoxyl radicals and metal-oxo complexes. Lipid alkoxyl radicals are presumed to be the species responsible for metal-amplified lipid peroxidation because of the chemical analogy of simple organic alkoxyl radicals to the hydroxyl radical. However, polyunsaturated fatty acid alkoxyl radicals exhibit a rich and diverse chemistry that is dominated by intramolecular cyclization to epoxyallylic radicals. Studies described herein demonstrate that the equilibrium between cyclization and ring-opening of epoxyallylic radicals lies overwhelmingly toward cyclization. Thus lipid alkoxyl radicals have a steady-state concentration that is so low that their contribution to metal-amplified lipid peroxidation is insignificant. In fact, the species responsible for metal amplification of lipid peroxidation appears to be the epoxyperoxyl radical formed by coupling the epoxyallylic radical to molecular oxygen.

HPLC Analysis of Lipid-derived Polyunsaturated Fatty Acid Peroxidation Products in Oxidatively Modified Human Plasma

2000 ◽  
Vol 46 (6) ◽  
pp. 829-836 ◽  
Author(s):  
Richard W Browne ◽  
Donald Armstrong
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Fatty Acid ◽  
Free Radical ◽  
Human Plasma ◽  
Polyunsaturated Fatty Acid ◽  
Human Blood Plasma ◽  
Clinical Markers ◽  
Oxidatively Modified ◽  
And Oxidative Stress

Abstract Background: Lipid peroxidation is a prominent manifestation of free radical activity and oxidative stress in biological systems. Diverse methodologies have been developed that measure a variety of lipid peroxidation products used as markers of lipid peroxidation processes. Methods: Hydroxy and hydroperoxy polyunsaturated fatty acid (PUFA) peroxidation products were analyzed in human blood plasma by reversed-phase HPLC after liquid-liquid extraction of total lipids and alkaline hydrolysis of lipid esters to liberate free PUFAs. An isocratic mobile phase containing 1 g/L acetic acid-acetonitrile-tetrahydrofuran (52:30:18, by volume) over 60 min duration, with ultraviolet absorbance detection at 236 nm by photodiode array, enabled the resolution and quantification of 13 regioisomeric hydroxy and hydroperoxy PUFAs. Results: As little as 250 μL of human plasma was utilized with an analytical range of 0.033–1.6 μmol/L for each compound. Intra- and interassay CVs for all compounds detected in normal or oxidatively modified human plasma were 3.2–11% and 4.7–12%, respectively. Analytical recoveries were 87–103%. Analysis of human plasma exposed to artificial oxidation with Cu2+ ion and hydrogen peroxide, a free radical-generating reaction, showed marked increases in hydroxy and hydroperoxy PUFA concentrations. Conclusion: Lipid-derived hydroxy and hydroperoxy PUFAs may be useful as clinical markers of lipid peroxidation and oxidative stress in the peripheral circulation.

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