http://atarazanas.sci.uma.es/docs/articulos/16671260.pdf

Role of reactive oxygen species in apoptosis: implications for cancer therapy.

Melatonin is a potent endogenous free radical scavenger, actions that are independent of its many receptor-mediated effects In the last several years, hundreds of publications have confirmed that melatonin is a broad-spectrum antioxidant Melatonin has been reported to scavenge hydrogen peroxide (H2O2), hydroxyl radical (HO·), nitric oxide (NO·), peroxynitrite anion (ONOO–), hypochlorous acid (HOCl), singlet oxygen (1O2), superoxide anion (O2–·) and peroxyl radical (LOO·), although the validity of its ability to scavenge O2–· and LOO· is debatable Regardless of the radicals scavenged, melatonin prevents oxidative damage at the level of cells, tissues, organs and organisms The antioxidative mechanisms of melatonin seem different from classical antioxidants such as vitamin C, vitamin E and glutathione As electron donors, classical antioxidants undergo redox cycling; thus, they have the potential to promote oxidation as well as prevent it Melatonin, as an electron-rich molecule, may interact with free radicals via an additive reaction to form several stable end-products which are excreted in the urine Melatonin does not undergo redox cycling and, thus, does not promote oxidation as shown under a variety of experimental conditions From this point of view, melatonin can be considered a suicidal or terminal antioxidant which distinguishes it from the opportunistic antioxidants Interestingly, the ability of melatonin to scavenge free radicals is not in a ratio of mole to mole Indeed, one melatonin molecule scavenges two HO· Also, its secondary and tertiary metabolites, for example, N1-acetyl-N2-formyl-5-methoxykynuramine, N-acetyl-5-methoxykynuramine and 6-hydroxymelatonin, which are believed to be generated when melatonin interacts with free radicals, are also regarded as effective free radical scavengers The continuous free radical scavenging potential of the original molecule (melatonin) and its metabolites may be defined as a scavenging cascade reaction Melatonin also synergizes with vitamin C, vitamin E and glutathione in the scavenging of free radicals Melatonin has been detected in vegetables, fruits and a variety of herbs In some plants, especially in flowers and seeds (the reproductive organs which are most vulnerable to oxidative insults), melatonin concentrations are several orders of magnitude higher than measured in the blood of vertebrates Melatonin in plants not only provides an alternative exogenous source of melatonin for herbivores but also suggests that melatonin may be an important antioxidant in plants which protects them from a hostile environment that includes extreme heat, cold and pollution, all of which generate free radicals

Significance of melatonin in antioxidative defense system: reactions and products.

An ethanol extract of the stem of Opuntia ficus-indica var. saboten (OFS) was assessed to determine the mechanism(s) of its antioxidant activity. The ethanol extract exhibited a concentration-dependent inhibition of linoleic acid oxidation in a thiocyanate assay system. In addition, the OFS extract showed dose-dependent free-radical scavenging activity, including DPPH radicals, superoxide anions (O(2)(*-)), and hydroxyl radicals (*OH), using different assay systems. The OFS ethanol extract was also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals in a Fenton's reaction mixture. Furthermore, the extract showed significant (p < 0.01) dose-dependent protection of mouse splenocytes against glucose oxidase-mediated cytotoxicity. Finally, the OFS extract was characterized as containing a high amount of phenolics (180.3 mg/g), which might be the active compounds responsible for the antioxidant properties of the OFS extract.

Antioxidant property of an ethanol extract of the stem of Opuntia ficus-indica var. saboten.

Mitochondria play a central role in energy metabolism within the cell. Mitochondrial dysfunctions lead to various neurodegenerative disorders and to the so-called "mitochondrial diseases". A vast amount of evidence points to the implication of mitochondria in such complex processes as apoptosis and cardioprotection. The purpose of this review is to present a recent state of our knowledge and understanding of the action of various therapeutically applied substances on mitochondria. These include antitumor, immunosuppressant, and antiviral drugs, potassium channel openers, sulfonylureas, and anesthetics. Some of these substances are specifically designed to affect mitochondrial functions. In other cases, drugs with primary targets in other cellular locations may modify mitochondrial functions as side effects. In any case, identification of mitochondria as primary or secondary targets of a drug may help us to better understand the drug's mechanism of action and open new perspectives for its application. As far as possible, the molecular mechanisms of the interference of particular drugs in the mitochondrial metabolism will be described. In some cases, metabolic routes in which the drugs interfere will also be briefly outlined.

Mitochondria as a Pharmacological Target

Polymorphonuclear leukocytes (PMNs) are the most abundant white cell in humans and an essential component of the innate immune system. PMNs are typically the first type of leukocyte recruited to sites of infection or areas of inflammation. Ingestion of microorganisms triggers production of reactive oxygen species and fusion of cytoplasmic granules with forming phagosomes, leading to effective killing of ingested microbes. Phagocytosis of bacteria typically accelerates neutrophil apoptosis, which ultimately promotes the resolution of infection. However, some bacterial pathogens alter PMN apoptosis to survive and thereby cause disease. Herein, we review PMN apoptosis and the ability of microorganisms to alter this important process.

Neutrophil apoptosis and the resolution of infection

Hydroxyl Radical as a Potential Intracellular Mediator of Polymorphonuclear Neutrophil Apoptosis

We report a case of severe priapism occurring in a patient with unstable hemoglobin, hemoglobin Koln, and underline several factors that may have contributed to this complication: abnormal plasticity of red cells, splenectomy, and cytomegalovirus infection. Since emergency treatment may prevent impotence, patients and parents should be educated about this complication. Am. J. Hematol. 74:73–74, 2003. © 2003 Wiley-Liss, Inc.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ajh.10374

Marie-José Grange

Papers

Hydroxyl Radical as a Potential Intracellular Mediator of Polymorphonuclear Neutrophil Apoptosis

Priapism in a patient with unstable hemoglobin: Hemoglobin Köln

Fatal acute pulmonary fibrosis in a patient treated by danazol for thrombocytopenia.