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Free radical mechanisms in tissue injury
01 Jan 1972-
TL;DR: This short review of free radicals discusses certain types of free radical, such as nitroxyl-radicals and free radicals stabilized by steric or derealization features, which are stable enough to be crystallised and stored at temperatures above 0°.
Abstract: Free radicals are molecules or molecular fragments containing a single unpaired electron. In general, free radicals are reactive chemically, some (e.g. HO•) being extremely reactive. However, certain types of free radical, such as nitroxyl-radicals and free radicals stabilized by steric or derealization features, are much less reactive and a few (e.g. diphenyl picryl hydrazyl) are stable enough to be crystallised and stored at temperatures above 0°. Table 1 gives the general structures of free radicals that will be discussed in this short review.
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TL;DR: This chapter discusses microsomal lipid peroxidation, a complex process known to occur in both plants and animals that involves the formation and propagation of lipid radicals, the uptake of oxygen, a rearrangement of the double bonds in unsaturated lipids, and the eventual destruction of membrane lipids.
Abstract: Publisher Summary This chapter discusses microsomal lipid peroxidation Lipid peroxidation is a complex process known to occur in both plants and animals It involves the formation and propagation of lipid radicals, the uptake of oxygen, a rearrangement of the double bonds in unsaturated lipids, and the eventual destruction of membrane lipids, producing a variety of breakdown products, including alcohols, ketones, aldehydes, and ethers Biological membranes are often rich in unsaturated fatty acids and bathed in an oxygen-rich, metal-containing fluid Lipid peroxidation begins with the abstraction of a hydrogen atom from an unsaturated fatty acid, resulting in the formation of a lipid radical The formation of lipid endoperoxides in unsaturated fatty acids containing at least 3 methylene interrupted double bonds can lead to the formation of malondialdehyde as a breakdown product Nonenzymic peroxidation of microsomal membranes also occurs and is probably mediated in part by endogenous hemoproteins and transition metals The direct measurement of lipid hydroperoxides has an advantage over the thiobarbituric acid assay in that it permits a more accurate comparison of lipid peroxide levels in dissimilar lipid membranes
11,945 citations
Journal Article•
TL;DR: Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional, and suggestions are made where such possibilities may be worth pursuing.
Abstract: Flavonoids are nearly ubiquitous in plants and are recognized as the pigments responsible for the colors of leaves, especially in autumn. They are rich in seeds, citrus fruits, olive oil, tea, and red wine. They are low molecular weight compounds composed of a three-ring structure with various substitutions. This basic structure is shared by tocopherols (vitamin E). Flavonoids can be subdivided according to the presence of an oxy group at position 4, a double bond between carbon atoms 2 and 3, or a hydroxyl group in position 3 of the C (middle) ring. These characteristics appear to also be required for best activity, especially antioxidant and antiproliferative, in the systems studied. The particular hydroxylation pattern of the B ring of the flavonoles increases their activities, especially in inhibition of mast cell secretion. Certain plants and spices containing flavonoids have been used for thousands of years in traditional Eastern medicine. In spite of the voluminous literature available, however, Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional. Suggestions are made where such possibilities may be worth pursuing.
4,663 citations
Cites background from "Free radical mechanisms in tissue i..."
...Administration of eriodictyol and (1)-catechin to mice also depressed the enhancement of in situ liver chemiluminescence produced by CCl4, which reacts with cytochrome P450 to initiate in vivo lipid peroxidation (Slater, 1984)....
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TL;DR: A comprehensive survey on the compositional properties of LDL relevant for its susceptibility to oxidation, on the mechanism and kinetics of LDL oxidation, and on the chemical and physico-chemical properties of HDL oxidized by exposure to copper ions is provided.
2,289 citations
TL;DR: An increased concentration of end products of lipid peroxidation is the evidence most frequently quoted for the involvement of free radicals in human disease, but it is likely that increased oxidative damage occurs in most, if not all, human diseases and plays a significant pathological role in only some of them.
2,204 citations
TL;DR: These various principles will be illustrated by considering several thiol compounds by scavenging biologically important reactive oxygen species by preventing their formation, or by repairing the damage they do.
1,772 citations
Cites background from "Free radical mechanisms in tissue i..."
...cal, CC13" [3]....
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...Radicals can react with other molecules in a number of ways [3]....
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98 citations
TL;DR: This book is excellent value, attractively presented and stimulating to read and is strongly recommended to all scientists searching for new insights into the complex problems of cancer research.
Abstract: The book is based on the Proceedings of a symposium held at Brunel University in July 1981 supported by the National Foundation for Cancer Research. The subject has been presented under three main headings; electron spin resonance (ESR); lipid peroxidation and activated intermediates, comprising 18 chapters. Discussion sessions are detailed, stimulating and skillfully edited. The application of ESR studies to cancer specifically and to biological problems in general is well reviewed in two chapters of the first section. Uterine cancer, which is a major, but declining, contributor to female deaths in the UK and other countries, shows interesting tissue ESR changes. Normal cervix and endometrium display strong signals but malignant tissue shows a reduced or undetectable signal. Evidence so far points to changes in peroxy radicals. Another example of preliminary but fascinating new data is the ESR spectra seen in leukaemic blood samples. In this case, an extra signal is found in leukaemic blood which is thought to arise from a disturbance in ascorbate metabolism. Loss of membrane polyunsaturated fatty acids by peroxidation will lead to cell damage as a result of structural changes and impairment of function. A less well-studied but equally important aspect of lipid peroxidation is the simultaneous formation of a large number of highly active peroxidic and aldehydic fragmentation molecules. Several such products show inhibitory properties towards cancer cells, with hydroxynonenal displaying the most potent activity. Malondialdehyde (MDA) is perhaps the best known of the secondary aldehydic products of lipid peroxidation. In this section it is said to be a major contributor to thiobarbituric acid reactivity (TBA) in both tissue and pure lipid systems in its free form. The adduct formed with TBA in such systems is indeed an MDA-TBA adduct, however, most workers in this field find that MDA is mainly derived from peroxidic precursors which decompose during the acid-heating stage of the TBA test. In the last section concise and interesting accounts are given of the microsomal activation of carbon tetrachloride to free radical intermediates and their involvement in liver damage, decompartmentalised iron in cancer and the antitumour antibiotics. This latter topic is an important area of current free radical research offering the potential to deliver site-specific free radicals to target DNA. Priced at £ 24 this book is excellent value, attractively presented and stimulating to read. It is strongly recommended to all scientists searching for new insights into the complex problems of cancer research.
72 citations
"Free radical mechanisms in tissue i..." refers background in this paper
..., 1976, 1980) is the possibility that the nitroxy radical may be transported to other regions of the cell in the form of an adduct with polyunsaturated fatty acid (Stier et al., 1982; Floyd, 1982b)....
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TL;DR: It is suggested that a major action of sporidesmin in the rat is to produce severe damage to capillary networks particularly in the lungs, in contrast to the sheep, for example, where the most serious developments apparently arise from a biliary mechanism.
23 citations
19 citations