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Toxicokinetics of Nerve Agents
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Marcel J. van der Schans, Hendrik P. Benschop, Christopher E. Whalley
Therefore, attention has been paid to pretreatment with highly reactive scavengers, which would intercept or destroy the nerve agent when it enters the bloodstream, before it could reach its target site. It is anticipated that effective scavengers will offer protection against both lethal and incapacitating effects of an acutely toxic dose. In addition, if a scavenger remains in circulation at an effective concentration during a relatively long period of time, the pretreatment will, a fortiori, protect against long-term exposure to low doses of a nerve agent (Benschop et al., 1998). It is further anticipated that bioscavengers will not induce adverse physiological effects, particularly when bioscavengers of human origin are applied.
Decarboxylation of 7-−14 C-Benzoic Acid
Published in Robert A. Greenwald, CRC Handbook of Methods for Oxygen Radical Research, 2018
Gary W. Winston, Arthur I. Cederbaum
The specificity of commonly used ·OH scavengers towards ·OH as compared to other radicals is not well known. Most of these compounds are rather nonspecific and may react with other radicals, especially those that have an oxidizing power similar to that of ·OH, and produce the same products. For example, Pry or and Tang9 demonstrated that ethylene can be generated from methional by a variety of radicals. Therefore, an understanding of the specificity of various scavengers would be of value, especially in studies in complex biological systems or in vivo studies where other techniques such as ESR spectroscopy may not be used readily.
Benzene Metabolism (Toxicokinetics and the Molecular Aspects of Benzene Toxicity)
Published in Muzaffer Aksoy, Benzene Carcinogenicity, 2017
Keith R. Cooper, Robert Snyder
A comparison of the results of Post and Snyder,58,59 Gilmour and Snyder,52,53 and Sawahata and Neal,74 using microsomal systems, suggest a similarity of the enzyme(s) responsible for the metabolism of benzene and phenol. Griffiths et al.49,50 and Snyder2 using isolated, reconstituted phenobarbital-induced rat hepatic mixed function oxidase suggest that the first step in benzene metabolism is predominantly mediated by cytochrome P-450 with the formation of an epoxide which rearranges to form phenol. Further metabolism is largely via free radical mechanisms. Treatment both in vivo and in vitro with free radical scavengers have demonstrated that the amount of covalent binding and adverse effects in vivo are prevented.
Chrysin Suppresses HT-29 Cell Death Induced by Diclofenac through Apoptosis and Oxidative Damage
Published in Nutrition and Cancer, 2021
Endogenous and exogenous antioxidants can prevent and repair damage caused by ROS by third line of defense through removing oxidatively modified proteins and prevent the accumulation of oxidized proteins by action of proteolytic enzymes, proteinases, proteases, and peptidases (16). Therefore, they are called as “free radical scavengers” and can improve the immune defence and lower the risk of disease and cancer. Enzymatic antioxidants, which include superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT), act by metabolizing superoxide and other peroxides. They act as endogenous antioxidant defence systems, which clear ROS activity and accumulation in cells and maintain redox balance. The initial route of protection against the free radicals is SOD, which catalyzes the formation of superoxide (O2-) to hydrogen peroxide (16). Nonenzymatic antioxidants include flavonoids, vitamin E, carotenoid, polyphenols, vitamin C and glutathione (17).
Nanoliposomes encapsulation of enriched phenolic fraction from pistachio hulls and its antioxidant, anti-inflammatory, and anti-melanogenic activities
Published in Journal of Microencapsulation, 2020
Ehsan Oskoueian, Ehsan Karimi, Reza Noura, Mahdi Ebrahimi, Negin Shafaei, Ensiyeh Karimi
The inflammation is a complex, well-orchestrated and considered as a protective process regulated by the release of various cellular and chemical mediators. In the presence of inflammation, the cellular production of ROS increases and may disrupt the cell function. The nitric oxide is a reactive nitrogen species (RNS) produced upon the activity of inducible nitric oxide synthase (iNOS) and is expressed primarily in macrophages after stimulation by LPS/INF-γ. To maintain the cellular metabolic activity and alleviate the inflammation, the free radicals are contracted via antioxidant enzymes such as superoxide dismutase, catalase, and the glutathione peroxidase and other antioxidants such as bioactive phytochemicals and vitamins provided from dietary sources. The PEF-NLs appeared to be the good NO scavenger (Table 2) since the IC50 value was below 200 µg/ml according to Tsai et al. (2007) classification for NO scavengers. In addition, the PEF-NLs is considered as strong inhibitors of NO production in LPS/IFN-γ stimulated RAW 264.7 cell lines (Figure 3(b)). The results revealed that the PEF-NLs not only directly scavenged the free radicals but also suppressed the iNOS, COX-2, and NF-κB as pro-inflammatory genes. Thus, the PEF-NLs acted through a different mechanism in modulating inflammation. The anti-inflammatory activity observed in the pistachio hulls observed in this study was consistent with the results reported by Grace et al. (2016a).
Human macrophage responses to metal-oxide nanoparticles: a review
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Camila Figueiredo Borgognoni, Joo Hyoung Kim, Valtencir Zucolotto, Harald Fuchs, Kristina Riehemann
ROS scavengers are useful to reduce the damage of oxidative stress. The body has an antioxidant defence system composed of enzymes (e.g. superoxide dismutase) and substances like glutathione and some vitamins. However, facing the abundance of ROS, several substances such as Trolox, PEG, BHA and NAPDH oxidase have been used in studies presenting efficient ROS scavenging abilities [59,73,78–80]. Interestingly, some metal oxide nanoparticles present this property, as is the case of cerium oxide nanoparticles. Cerium oxide exhibit catalytic properties since they present a reversibility of the oxidation states Ce+3 and Ce+4 that leads to oxygen vacancies [81]. Lord et al. [82] investigated the antioxidant properties of cerium oxide nanoparticles in U-937 derived macrophages (PMA-differentiated) exposing the cells for up to 72 h to the nanoparticle. The authors demonstrated the uptake of the nanoparticles by the cells leading to a continuous intracellular ROS scavenger action.