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Marine Polysaccharides from Algae
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Wen-Yu Lu, Hui-Jing Li, Yan-Chao Wu
Oxygen is the key substance in the normal metabolic activities of aerobic organisms. In the environment of high redox potential, organisms inevitably produce reactive oxygen species (ROS), including hydrogen peroxide (H2O2), hydroxyl radical (•OH), peroxyl radical (ROO-), superoxide anion (•O2-) and nitroxide radical (NO•) (Wu et al., 2015). ROS play an important role in various physiological activities of organisms. Low or moderate concentrations of ROS prevent infectious agents from infecting host cells and interfering with cell mitosis (Valko et al., 2007). High concentration of ROS may destroy the balance of pro-oxidants/antioxidants in organisms and cause oxidative stress (Valko et al., 2006).
Experimental Results on Cellular and Subcellular Systems Exposed to Low-Frequency and Static Magnetic Fields
Published in Ben Greenebaum, Frank Barnes, Biological and Medical Aspects of Electromagnetic Fields, 2018
Myrtill Simkó, Mats-Olof Mattsson
Oxidative stress is the imbalance between the production of prooxidants and antioxidants. Oxidative stress is recognized as a main mechanism by which MF might induce toxicity. Reactive nitrogen species (RNS), derived from nitric oxide (NO), and superoxide are produced via the enzymatic activity of inducible nitric oxide synthase 2 (NOS2) and NADPH oxidase, respectively. The formation and release of ROS is closely connected to the immune defense system and especially to phagocytic processes. Thus, ROS formation is part of the cascade of events in the antimicrobial action of phagocytic cells, called oxidative burst, which results from the assembly of a complex electron transport system in the plasma membrane. High levels of ROS can lead to a number of damaging pathological consequences in cells and the organism, including lipid peroxidation, protein damage, deactivation of enzymatic activities, and DNA modification and pro-inflammatory processes. In the normal cellular biochemistry, there is a balance between free radical formation and the action of an antioxidative system. A number of primary antioxidant enzymes such as different dismutases, catalases, reductases, or peroxidases are known to neutralize the amounts of ROS. Irregularity or disturbance in the redox homeostasis by increased quantities of ROS or by the inhibition of the action of antioxidants can lead to cellular oxidative stress causing direct oxidative damages in cells and tissues, and may also initiate inflammatory processes. Other modulations in cell functions via signal transduction processes can furthermore be induced. Therefore, oxidative stress caused by the formation of radical oxygen and nitrogen species plays a decisive role in cytotoxicity and inflammation, eventually leading to the onset of pathophysiological alterations and pathogenesis.
Plant-Mediated Biosynthesis of Nanoparticles
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Majid Darroudi, Mohammad Ehsan Taghavizadeh Yazdi, Mohammad Sadegh Amiri
Cerium oxide nanoparticles (CeO2-NPs) have captured the interest of many researchers in nanotechnology since they have many practical applications such as catalysts [156], sustainable pollutant removers [157], antimicrobial agents [158], antioxidants [159], neuronal protectors [160], biosensors [161], and environment [162]. Normally, cerium has two oxidation states, i.e., Ce3+ and Ce4+, and it can be taken from this fact that cerium dioxide can have two diverse oxide forms, i.e., CeO2 (Ce4+) or Ce2O3 (Ce3+), in bulk material [163]. The cerium oxide lattice accommodates a cubic fluorite structure, with both forms (Ce3+ and Ce4+) capable of coexisting on its surface. Thus, it can be stated that CeO2-NPs contain upgraded redox features in comparison to the bulk materials. In addition, one can observe the crucial function of mixed valance state in hunting the reactive oxygen and nitrogen species. CeO2-NPs have been shown to be effective in opposing pathologies that are related to chronic oxidative stress and inflammation. Also, in accordance with various reports, CeO2-NPs seem to contain multiple enzymes, such as superoxide oxidase, catalase, and oxidase, and mimetic qualities; for this reason, they have been of interest in biological fields, including bioanalysis [164,165], biomedicine [166], and drug delivery [167]. Various routes and synthesis procedures have been assessed for the purpose of fabricating CeO2-NPs, such as solution precipitation [168], sono-chemical method [169], hydrothermal process [170], spray pyrolysis [171], and sol–gel methods [172]. Nonetheless, the use of these techniques is rife with different drawbacks, such as employment of toxic solvents and reagents, requisition of high temperature and pressure, and the demand for external additives such as stabilizing or capping agents during the reaction. Although similar core elements apply for every type of CeO2-NPs, the same biological impacts are not exhibited by all of them. Due to the utilization of different NPs and the inducement of various physiochemical parameters, some reports have announced the pro-oxidant toxicity of these particular particles in some specific cases, while other studies have suggested their antioxidant protective outcomes in different situations. The production of CeO2-NPs with diverse physicochemical qualities is dependent on the synthesizing procedure, type of the employed stabilizing agent, and the Ce3+/Ce4+ surface ratio [173,174]. Particles as small as <10 nm have been achieved through some green synthesizing procedures of CeO2-NPs. As has been suggested by some reports, the plant-based synthesis of CeO2-NPs can furnish larger NPs than those from biopolymer and nutrient-based techniques, although they possess antibacterial properties that have displayed high levels of cytotoxicity to bacterial cells [175,176].
Protective properties of filamentous blue–green alga Spirulina against the oxidative stress induced by cadmium in freshwater mussel Unio ravoisieri
Published in Chemistry and Ecology, 2019
Abdelhafidh Khazri, Ali Mezni, Badreddine Sellami, Samir Touaylia, Ichrak Noiyri, Hamouda Beyrem, Ezzeddine Mahmoudi
In the present study, the parameters of antioxidant status, SOD, CAT, GST were significantly decreased maybe either due to the excessive ROS synthesis, indicating Cd-induced oxidative stress in this organ. The depression of these enzyme activities, as observed in the present study, reflects perturbations in normal oxidative mechanisms during Cd toxicity. In addition, PC and MDA were found significantly increased in the digestive gland after Cadmium-treated mussel, suggesting that Cadmium treatment caused oxidative damage to the proteins and lipids in this organ. Principal component analysis (PCA) loading plot is shown in Figure 6. Positive associations between SOD, CAT, GST are identified when these variables are clustered together (< 90° angle), with smaller angles representing stronger associations. Conversely, MDA and PC on the opposite side of the origin (approximately 180°) are negatively associated with SOD, CAT and GST. Based on the results, we concluded that exposed to Cd they induced higher ROS production and depletion in the antioxidant enzyme activities and become unable to effectively scavenge the excessive ROS at the early toxicity and maintain the redox equilibrium. Oxidative stress is a result of imbalances in the equilibrium status between pro-oxidants and antioxidants that would result in a significant damage to tissues and organs.
Redox homeostasis in sport: do athletes really need antioxidant support?
Published in Research in Sports Medicine, 2019
Ambra Antonioni, Cristina Fantini, Ivan Dimauro, Daniela Caporossi
Pro-oxidant refers to any endobiotic or xenobiotic that induces oxidative stress either by generation of ROS or by inhibition of the antioxidant systems. It can include all reactive, free radical molecules contained in cells or tissue. Biologically relevant ROS include hydroxyl radical (OH•), superoxide anion (O−2), peroxyl radical (RO2•), peroxynitrite (ONO2−), hypochlorous acid (HOCl−), hydrogen peroxide (H2O2), singlet oxygen (1O2), and ozone (O3) (Valko et al., 2007). Reactive nitrogen and sulphur species also constitute separate radical groups with independent biological functions (Giles & Jacob, 2002). Environmental pro-oxidants may be classified into several categories such as drugs, transition metals, pesticide, PA, and, under certain circumstances, even the antioxidants (e.g. vitamins and polyphenols) (Rahal et al., 2014).
The impact of exercise training on the lipid peroxidation metabolomic profile and respiratory infection risk in older adults
Published in European Journal of Sport Science, 2019
Diana Silva, Eduardo Arend, Silvia M. Rocha, Alisa Rudnitskaya, Luís Delgado, André Moreira, Joana Carvalho
Oxidative stress plays a major role in low-grade inflammation, which is characteristic of age-associated diseases (Cannizzo, Clement, Sahu, Follo, & Santambrogio, 2011). Oxidative stress theory of aging stipulates that reactive oxygen species, like peroxides and aldehydes, play a role in oxidative damage to cells and in the imbalance of pro-oxidants and antioxidants, resulting in apoptosis or a progressive decrease in cellular function, which lead to immunosenescence (Cannizzo et al., 2011). However, evidence of this relationship is still controversial (Salmon, Richardson, & Perez, 2010). Lipid peroxidation increases significantly with age, although this increase seems to be prevented by lifelong competitive training (Barranco-Ruiz et al., 2017), but also with resistance training (Vincent, Vincent, Braith, Lennon, & Lowenthal, 2002).