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Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the dysfunction and death of motor neurons through multifactorial mechanisms that remain unclear. ALS has been recognized as a multisystemic disease, and the potential role of skeletal muscle in disease progression has been investigated. Reactive aldehydes formed as secondary lipid peroxidation products in the redox processes react with biomolecules, such as DNA, proteins, and amino acids, resulting in cytotoxic effects. 4-Hydroxy-2-nonenal (HNE) levels are elevated in the spinal cord motor neurons of ALS patients, and HNE-modified proteins have been identified in the spinal cord tissue of an ALS transgenic mice model, suggesting that reactive aldehydes can contribute to motor neuron degeneration in ALS. One biological pathway of aldehyde detoxification involves conjugation with glutathione (GSH) or carnosine (Car). Here, the detection and quantification of Car, GSH, GSSG (glutathione disulfide), and the corresponding adducts with HNE, Car-HNE, and GS-HNE, were performed in muscle and liver tissues of a hSOD1G93AALS rat model by reverse-phase high-performance liquid chromatography coupled to electrospray ion trap tandem mass spectrometry in the selected reaction monitoring mode. A significant increase in the levels of GS-HNE and Car-HNE was observed in the muscle tissue of the end-stage ALS animals. Therefore, analyzing variations in the levels of these adducts in ALS animal tissue is crucial from a toxicological perspective and can contribute to the development of new therapeutic strategies.

Copperiiiii tetraglycine complexes were investigated for their ability to catalyze the autoxidation of sulfite resulting in oxidative DNA damage. The focus of this work is on DNA damage by Cuiii and oxysulfur radicals formed by the oxidation of Siv oxides by dissolved oxygen in the presence of Cuii tetraglycine complexes. The results suggest that sulfite is rapidly oxidized by oxygen in the presence of Cuii complexes producing Cuiii tetraglycine, which can be monitored spectrophotometrically at 365 nm. A synergistic effect of Cuii with a second metal ion Niii, Coii or Mnii traces was observed.

NiIIGGH GGH glycylglycylhistidine reacts rapidly with Siv, in air-saturated solution, to produce NiIIIGGH. A mechanism is proposed where initial NiIIIoxidizes SO32−to SO3−, which reacts with dissolved oxygen to produce SO5−, initiating radical chain reactions. DNA strand breaks and 8-oxo-7,8-dihydro-2′-deoxyguanosine formation were observed in air-saturated solutions containing micromolar concentrations of Niii and Siv. The extent of DNA damage showed dependence on the ratio of the NiIIGGH : Siv concentrations and the ionic strength.

In the present work, we study the reaction of singlet oxygen (¹O2) with isolated DNA. Emphasis is placed on the identification and quantitative measurement of the DNA modifications that are produced by the reaction of ¹O2 with DNA. For this purpose, calf-thymus DNA was incubated with the endoperoxide of N,N'-di(2,3-dihydroxypropyl)-1,4-naphthalenedipropanamide, a chemical generator of ¹O2. Thereafter, DNA was digested, and the resulting oxidized nucleosides were measured by means of a recently optimized high-performance-liquid-chromatography tandem-mass-spectrometry assay. It was found that, among the different DNA lesions observed, 7,8-dihydro-8-oxo-2'-deoxyguanosine is the major ¹O2-mediated DNA-damage product. Interestingly, cyclobutane pyrimidine dimers, oxidized pyrimidine bases, 7,8-dihydro-8-oxo-2'-deoxyadenosine, and 2,6-diamino-5-formamido-4-hydroxypyrimidine are not formed, at least not in detectable amounts, following treatment of DNA with the ¹O2 generator. The reported results strongly suggest that the decomposition of the endoperoxide provides a pure source of ¹O2, and that reaction of ¹O2 with isolated DNA induces the specific formation of 7,8-dihydro-8-oxo-2'-deoxyguanosine.

Experimental and epidemiological evidence suggests that lycopene, a carotenoid present in tomatoes, tomato products, and several fruits and vegetables, may play a role in preventing certain cancers in humans. We have investigated the effect of lycopene pretreatment on lipid peroxidation, oxidative damage to DNA, and histopathological changes in liver of animals subjected to intraperitoneal (ip) ferric nitrilotriacetate (Fe-NTA) administration. Compared with control rats, liver of Fe-NTA-treated animals showed a significant increase in the 8-oxo-7,8-dihydro-2′-deoxyguanosine level and a 75% increase in malondialdehyde accumulation concomitant with histopathological changes. Five days of lycopene pretreatment (10 mg/kg body weight, ip) almost completely prevented liver biomolecule oxidative damage and protected the tissue against the observed histological alterations.

Abstract5-Aminolevulinic acid (ALA) is a heme precursor that accumulates in lead poisoning and inborn porphyrias. It has been shown to produce reactive oxygen species upon metalcatalyzed aerobic oxidation and to cause oxidative damage to proteins, liposomes, DNA, and subcellular structures. Studies have also shown that ALA may condense to yield the cyclic product 3,6-dihydropyrazine 2,5-dipropanoic acid (DHPY). Here we propose that DHPY could be involved in DNA damage in the presence of high concentrations of ALA. Exposure of plasmid pUC19 DNA to low concentrations of DHPY (2 10 M) in the presence of 0.1 mM Cu[2+] ions causes DNA strand breaks, as demonstrated by agarose gel electrophoresis. It was also shown that in the presence of Cu[2+] ions DHPY is able to increase the oxidation of monomeric 2deoxyguanosine to form 8- oxo-7,8-dihydro-2deoxyguanosine as inferred from high performance liquid chromatography measurements using electrochemical detection. Addition of a metal chelator (bathocuproine, 0.5 mM), the DNA compacting polyamines spermidine (1 mM) and spermine (1 mM) or antioxidant enzymes such as superoxide dismutase (10 g/ml) and catalase (20 g/ml) protect the DNA against these damages. The data presented here are discussed with respect to the increased frequency of liver cancer in patients with acute intermittent porphyria.

A high incidence of cancer has been correlated with chronic iron overload, and carotenoids are of interest as possible anticarcinogens. We have investigated the effect of lycopene on lipid peroxidation and on the formation of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) in CV1-P monkey cells exposed to ferric nitrilotriacetate (Fe-NTA) plus ascorbate. Cells supplemented with lycopene (20 pmol/106 cells) showed a reduction of 86% in Fe-NTA/ascorbate-induced lipid peroxidation (TBARS). Levels of 8-oxodGuo rose from 1.59 ± 0.09 residues/106 dGuo in the control cells to 14.02 ± 0.41 residues/106 dGuo after incubation with (1:4 mM) Fe-NTA/ascorbate (40 μM). Lycopene supplementation decreased in 77% the 8-oxodGuo levels in Fe-NTA/ascorbate-treated cells. These results indicate that lycopene can protect mammalian cells against membrane and DNA damage and possibly play a protective role against tumor promotion associated with oxidative damage.

Cellular accumulation of 5-aminolevulinic acid (ALA), the first specific intermediate of heme biosynthesis, is correlated in liver biopsy samples of acute intermittent porphyria affected patients with an increase in the occurrence of hepatic cancers and the formation of ferritin deposits in hepatocytes. 5-Aminolevulinic acid is able to undergo enolization and to be subsequently oxidized in a reaction catalyzed by iron complexes yielding 4,5-dioxovaleric acid (DOVA). The released superoxide radical (O•−2) is involved in the formation of reactive hydroxyl radical (•OH) or related species arising from a Fenton-type reaction mediated by FeII and CuI. This leads to DNA oxidation. The metal catalyzed oxidation of ALA may be exalted by the O•−2 and enoyl radical-mediated release of FeII ions from ferritin. We report here the potentiating effect of ferritin on the ALA-mediated cleavage of plasmid DNA and the enhancement of the formation of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo). Plasmid pBR322 was incubated with ALA and varying amounts of purified ferritin. DNA damage was assessed by gel electrophoresis analysis of the open and the linear forms of the plasmid from the native supercoiled structure. Addition of either the DNA compacting polyamine spermidine or the metal chelator ethylenediaminetetraacetic acid (EDTA) inhibited the damage. It was also shown that ALA in the presence of ferritin is able to increase the oxidation of the guanine moiety of monomeric 2′-deoxyguanosine (dGuo) and calf thymus DNA (CTDNA) to form 8-oxodGuo as inferred from high performance liquid chromatography (HPLC) measurements using electrochemical detection. The formation of the adduct dGuo-DOVA wasdetected in CTDNA upon incubation with ALA and ferritin. In a subsequent investigation, the aldehyde DOVA was also able to induces strand breaks in pBR322 DNA.

The tetraruthenated porphyrin, u.‐[/wes0‐5,1O,15,2O‐tet‐ra(pyridyl)porphyrin]tetrakis[ftis‐(bipyridine)chloride ruthenium(II)] (TRP) is a supramolecular cationic species. The aim of the present investigation was to evaluate the photodynamic properties of TRP and Zn‐TRP to damage DNA with emphasis on the mechanistic aspects. The ability for tetraruthenated porphyrin derivatives to induce photosensitization reactions has been determined using 2′‐deoxyguanosine as a DNA model compound. The main photooxidation products of the targeted nucleoside were identified and classified according to their mechanisms of formation, involving either a radical pathway (type I) or a singlet oxygen‐mediated mechanism (type II). Quantification of the different oxidation products provides a means to evaluate the relative contribution of type I and type II pathways associated with the oxidative photosensitization of 2′‐deoxyguanosine by tetraruthenated porphyrin derivatives. Results indicate that x02 plays a major role in the mechanism of photooxidation mediated by these porphyrin derivatives. In addition an increase of the photosensitizing effect in the presence of zinc is observed. For each sensitizer, the ratio between type II and type I photoproducts has been calculated and compared to that of other known dyes such as methylene blue and riboflavin.