Search results for "free radicals"

Electron spin resonance as a tool to monitor the influence of novel processing technologies on food properties

2020

Abstract Background Nowadays, electron spin resonance (ESR) is widely used as a powerful, non-destructive and very sensitive technique for the detection of free radicals in food systems. It can be applied for the direct identification of highly reactive oxygen species, organic and inorganic paramagnetic species and screening of food for potential toxicity. Its applications cover investigating food oxidative stability and properties of irradiated foods including fruits and vegetables, meats and fishes, spices, cereal grains, and oil seeds. Scope and approach This review aims at providing specialists in food science and industry with the fundamentals of ESR spectroscopy, typical radicals pres…

Electron paramagnetic resonance in a biomedical laboratory

2013

Role of Free Radicals and Antioxidant Signaling in Skeletal Muscle Health and Pathology

2009

Skeletal muscle contraction, growth, differentiation and adaptation are governed by complicated biological mechanisms still being studied intensively. Generation of reactive oxygen and nitrogen species (RS) is one of the most prominent events during contractile activity that could influence muscle function and health. While RS generation is known to cause oxidative stress, activate certain pathogenic pathways and aging, they also serve as useful signaling molecules to regulate gene expression of proteins and enzymes that play a vital role in the normal muscle function and defense against detrimental effects of RS. The purpose of the present review is two-fold: first, to provide an overview …

Mitochondria as sources and targets of damage in cellular aging.

2011

Mitochondria are considered as the most important cellular sources and targets of free radicals. They are also a source of signalling molecules that regulate cell cycle, proliferation, and apoptosis. Denham Harman postulated the free radical theory of aging in 1956. Previously Rebecca Gershman showed that radiation toxicity could be attributed to free radical damage. Subsequently, Jaime Miquel formulated the mitochondrial free radical theory of aging. We have shown that mitochondrial size, membrane potential, inner membrane mass and peroxide production is altered inside cells in old animals. These result in an increase in the oxidative damage to mitochondrial DNA with aging that can be prev…

Diindeno-fusion of an anthracene as a design strategy for stable organic biradicals

2016

The consequence of unpaired electrons in organic molecules has fascinated and confounded chemists for over a century. The study of open-shell molecules has been rekindled in recent years as new synthetic methods, improved spectroscopic techniques and powerful computational tools have been brought to bear on this field. Nonetheless, it is the intrinsic instability of the biradical species that limits the practicality of this research. Here we report the synthesis and characterization of a molecule based on the diindeno[b,i]anthracene framework that exhibits pronounced open-shell character yet possesses remarkable stability. The synthetic route is rapid, efficient and possible on the gram sca…

Translocation versus cyclisation in radicals derived from N-3-alkenyl trichloroacetamides

2011

Under radical reaction conditions, two different and competitive reaction pathways were observed for N-(alpha-methylbenzyl)trichloroacetamides with a N-3-cyclohexenyl substituent: 1,4-hydrogen translocation and radical addition to a double bond. However, for radicals with an acyclic alkenyl side chain, the direct cyclisation process was exclusively observed. The dichotomy between translocation and direct radical cyclisation in these substrates has been theoretically studied using density functional theory (DFT) methods at the B3LYP/6-31G** computational level.

EPR, ENDOR and TRIPLE Resonance and MO Studies on Ubiquinones (Q-n): Comparison of Radical Anions and Cations of Coenzymes Q-10 and Q-6 with the Mode…

1997

Radical anions and cations of the biologically important coenzymes Q-6 and Q-10, which have 6 and 10 unsaturated isoprene units in their side chains, respectively, have been generated in various solvents, and the results compared with those obtained for Q-0, a ubiquinone with no isoprene units, and for decylubiquinone Q-2 which has a saturated side chain. Hyperfine splitting constants (hfsc) of methyl and methoxy protons of the substituents in the quinone ring, and beta and gamma protons of the side chain were measured by EPR and ENDOR spectroscopy for both the radical anions and cations of Q-0, Q-6 and Q-10, and for the radical anion of Q-2. The relative signs of the hfsc were determined b…

Experimental and Theoretical Studies on Magnetic Exchange in Silole-Bridged Diradicals.

2006

International audience; Five bis(tert-butylnitroxide) diradicals connected by a silole [2,5-R2-3,4-diphenylsilole; R = Me3CN(®O.bul.)Z; Z = p-C6H4 (7a), p-C6H4C6H4-p (7b), 1,4-naphthalenediyl (7c), m-C6H4 (7d)] or a thiophene [2,5-R2-thiophene; R = p-Me3CN(®O.bul.)C6H4 (12)] ring as a coupler were studied. Compd. 12 crystallizes in the orthorhombic space group Pna21 with a 20.752(5), b 5.826(5), and c 34.309(5) .ANG.. X-ray crystal structure detn., electronic spectroscopy, variable-temp. EPR spectroscopy, SQUID measurements and DFT computations (UB3LYP/6-31+G*) were used to study the mol. conformations and electronic spin coupling in this series of mols. Whereas compds. 7b, 7c, and 7d are q…

Comparison of Protective Effects against Reactive Oxygen Species of Mononuclear and Dinuclear Cu(II) Complexes with N-Substituted Benzothiazolesulfon…

2005

Copper(II) complexes of N-benzothiazolesulfonamides (HL1=N-2-(4-methylphenylsulfamoyl)-6-nitro-benzothiazole, HL2=N-2-(phenylsulfamoyl)-6-chloro-benzothiazole, and HL3=N-2-(4-methylphenylsulfamoyl)-6-chloro-benzothiazole) with ammonia have been synthesized and characterized. The crystal structures of the [Cu(L1)2(NH3)2].2MeOH, [Cu(L2)2(NH3)2], and [Cu(L3)2(NH3)2] compounds have been determined. Compounds and present a distorted square planar geometry. In both compounds the metal ion is coordinated by two benzothiazole N atoms from two sulfonamidate anions and two NH3 molecules. Complex is distorted square-pyramidal. The Cu(II) ion is linked to the benzothiazole N and sulfonamidate O atoms o…

Mitochondrially encoded cysteine predicts animal lifespan

2007

Summary The role of genetic factors in the determination of lifespan is undisputed. However, numerous successful efforts to identify individual genetic modulators of longevity have not yielded yet a quantitative measure to estimate the lifespan of a species from scratch, merely based on its genomic constitution. Here, we report on a meta-examination of genome sequences from 248 animal species with known maximum lifespan, including mammals, birds, fish, insects, and helminths. Our analysis reveals that the frequency with which cysteine is encoded by mitochondrial DNA is a specific and phylogenetically ubiquitous molecular indicator of aerobic longevity: long-lived species synthesize respirat…