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Extracts of herbs and spices are increasingly of interest in the food industry because they retard oxidative degradation of lipids. There is also increasing interest in the antiviral activity of plant products. A liquid, deodorized rosemary extract and an oily extract of a mixture of Provençal herbs were tested for antioxidant and antiviral action in vitro. The rosemary extract (Herbor 025) and the extract of Provençal herbs (Spice Cocktail) inhibited peroxidation of phospholipid liposomes with 50% inhibition concentration values of 0.0009% (v/v) and 0.0035% (v/v), respectively. Herbor 025 and the spice cocktail (at 0.2%, v/v) reacted with trichloromethylperoxyl radical with calculated rates of 2.7 × 104 s −1 and 1.5 × 103 s −1, respectively. The main active components in the herbal preparations, carnosol and carnosic acid, at 0.05% (v/v) react with rate constants of (1–3) × 106 M −1 sec −1 and 2.7 × 107 M −1 sec −1, respectively. Both extracts show good antioxidant activity in the Rancimat test, especially in lard. Herbor 025 and the spice cocktail inhibited human immunodeficiency virus (HIV) infection at very low concentrations which were also cytotoxic. However, purified carnosol exhibited definite anti-HIV activity at a concentration (8μM) which was not cytotoxic. Both preparations promoted some DNA damage in the copper-phenanthroline and the bleomycin-iron systems. The two herbal preparations possess antioxidant properties that may make them useful in the food matrix.
Free radicals and other reactive oxygen species (ROS) are constantly formed in the human body, often for useful metabolic purposes. Antioxidant defenses protect against them, but these defenses are not completely adequate, and systems that repair damage by ROS are also necessary. Mild oxidative stress often induces antioxidant defense enzymes, but severe stress can cause oxidative damage to lipids, proteins, and DNA within cells, leading to such events as DNA strand breakage and disruption of calcium ion metabolism. Oxidative stress can result from exposure to toxic agents, and by the process of tissue injury itself. Ozone, oxides of nitrogen, and cigarette smoke can cause oxidative damage; but the molecular targets that they damage may not be the same.
Chloroplasts isolated from leaves of spinach‐beet ( Beta vulgaris L. ssp. vulgaris ) do not catalyse the hydroxylation of p ‐coumaric acid in the dark unless a reductant (such as ascorbate, NADH or NADPH) is added. Superoxide dismutase has no effect on this reaction. Illuminated chloroplasts catalyse the hydroxylation in the absence of added reductant. This reaction is completely inhibited by superoxide dismutase, but catalase has little effect. Both hydroxylation in the light and hydroxylation in the dark in the presence of reductants are inhibited by diethyldithiocarbamate, EDTA, cyanide and 2‐mercaptoethanol. It is proposed that O 2 .− generated by illuminated chloroplasts is involved in the provision of a reductant to the enzyme phenolase.
Traditional medicinal plants have a long history of therapeutic use. The beneficial health effects of medicinal plants rich in polyphenols are often attributed to their potent antioxidant activities, as established in vitro, since diets rich in polyphenols are epidemiologically associated with a decreased incidence of age-related diseases in humans. However, medicinal plants may also exert pro-oxidant effects that up-regulate endogenous protective enzymes. Care is needed when studying the biological effects of medicinal plants in cell culture because some polyphenols oxidize readily in culture media. This review summarizes the data we have obtained from in vitro and in vivo (Caenorhabditis elegans) studies examining the diverse effects of traditional medicinal plants and their modes of action.
Peroxidases in Chemistry and Biology, Vols. 1 and 2 Edited by J EVERSE, K E EVERSE & M B GRISHAM CRC Press, Boca Raton, Florida, 1991The Cell Biology of Inflammation in the Gastrointestinal Tract edited by T.J. Peters. Corners Publications, Hull, U.K. pp. xvii + 389. Price £39.00
N-acetylcysteine has been widely used as an antioxidant in vivo and in vitro. Its reaction with four oxidant species has therefore been examined. N-acetylcysteine is a powerful scavenger of hypochlorous acid (HOCl); low concentrations are able to protect α 1-antiproteinase against inactivation by HOCl. N-acetylcysteine also reacts with hydroxyl radical with a rate constant of 1.36 × 1010 M−1s−1, as determined by pulse radiolysis. It also reacts slowly with H2O2, but no reaction of N-acetylcysteine with superoxide (O2 −) could be detected within the limits of our assay procedures.
No abstract is provided for this article.
Both ferrioxamine and desferrioxamine react with the hydroxyl radical with a second order rate constant equal to 1.3 × 1010 M−1 s−1. Conditions for the use of desferrioxamine as a probe for the role of iron salts in the formation of hydroxyl radicals in biochemical systems are discussed.
Conference Article| February 01 1976 Production of the Superoxide Radical by Horseradish Peroxidase BARRY HALLIWELL; BARRY HALLIWELL 1Department of Biochemistry, King's College London, Strand, London WC2R2LS, U.K. Search for other works by this author on: This Site PubMed Google Scholar SUNIL AHLUWALIA SUNIL AHLUWALIA 2Department of Biochemistry, King's College London, Strand, London WC2R2LS, U.K. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1976) 4 (1): 73–74. https://doi.org/10.1042/bst0040073 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation BARRY HALLIWELL, SUNIL AHLUWALIA; Production of the Superoxide Radical by Horseradish Peroxidase. Biochem Soc Trans 1 February 1976; 4 (1): 73–74. doi: https://doi.org/10.1042/bst0040073 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search This content is only available as a PDF. © 1976 Biochemical Society1976 Article PDF first page preview Close Modal You do not currently have access to this content.
A bstract : In the late 1950's free radicals and antioxidants were almost unheard of in the clinical and biological sciences but chemists had known about them for years in the context of radiation, polymer and combustion technology. Daniel Gilbert, Rebeca Gerschman and their colleagues related the toxic effects of elevated oxygen levels on aerobes to those of ionizing radiation, and proposed that oxygen toxicity is due to free radical formation, in a pioneering paper in 1956. Biochemistry owes much of its early expansion to the development and application of chromatographic and electrophoretic techniques, especially as applied to the study of proteins. Thus, superoxide dismutase (SOD) enzymes (MnSOD, CuZnSOD, FeSOD) were quickly identified. By the 1980's Molecular Biology had evolved from within biochemistry and microbiology to become a dominant new discipline, with DNA sequencing, recombinant DNA technology, cloning, and the development of PCR representing milestones in its advance. As a biological tool to explore reaction mechanisms, SOD was a unique and valuable asset. Its ability to inhibit radical reactions leading to oxidative damage in vitro often turned out to be due to its ability to prevent reduction of iron ions by superoxide. Nitric oxide (NO·) provided the next clue as to how SOD might be playing a critical biological role. Although NO· is sluggish in its reactions with most biomolecules it is astoundingly reactive with free radicals, including superoxide. Overall, this high reactivity of NO· with radicals may be beneficial in vivo , e.g. by scavenging peroxyl radicals and inhibiting lipid peroxidation. If reactive oxygen species are intimately involved with the redox regulation of cell functions, as seems likely from current evidence, it may be easier to understand why attempts to change antioxidant balance in aging experiments have failed. The cell will adapt to maintain its redox balance. Indeed, transgenic animals over‐expressing antioxidants show some abnormalities of function. There must therefore be a highly complex interrelationship between dietary, constitutive, and inducible antioxidants within the body, under genetic control. The challenge for the new century is to be able to understand these relationships, and how to manipulate them to our advantage to prevent and treat disease.
FREE RADICALS and other reactive oxygen species are constantly formed in the human body. Many of them serve useful physiological func tions, but they can be toxic when generated in excess and this toxicity is often aggravated by the presence of ions of such transition metals as iron or copper. Excess generation of reactive oxygen species within tissues can damage DNA, lipids, proteins and carbohydrates. Which of these is the most important target of damage depends upon the cell type subjected to the oxidative stress and upon how it is imposed.
