Journal articles: 'Antioxidant defences'

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Eaton, Simon. "The biochemical basis of antioxidant therapy in critical illness." Proceedings of the Nutrition Society 65, no. 3 (August 2006): 242–49. http://dx.doi.org/10.1079/pns2006501.

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During critical illness free radical production may increase as a result of, for example, sepsis or tissue trauma. In addition, because of a potential for increased losses, and the possibility of inadequate nutrition, the antioxidant defences of the body may become compromised. Thus, the delicate balance between free radicals and antioxidants may be disturbed. Various nutritional and pharmacological strategies to enhance antioxidant defences have been proposed, which aim either to maintain or enhance endogenous antioxidant stores or to provide alternative antioxidant agents. Trace elements and amino acids are particularly important, and their synergistic role in the maintenance of the body's antioxidant defence network will be discussed.

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Viña, Jose, Mari-Carmen Gomez-Cabrera, and Consuelo Borras. "Fostering antioxidant defences: up-regulation of antioxidant genes or antioxidant supplementation?" British Journal of Nutrition 98, S1 (October 2007): S36—S40. http://dx.doi.org/10.1017/s0007114507839596.

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Vitamins have traditionally been considered as food components that are required in the normal diet to prevent deficiencies. However, a newer concept of the function of vitamins in nutrition has taken them beyond simply prevention of deficiency symptoms. This concept considers that many vitamins, when taken in relatively larges doses, have important functions beyond preventing deficiencies. Linus Pauling was instrumental in putting forward this concept, particularly for vitamin C. Thus, relatively high intakes of vitamins, and in particular vitamins C and E which are antioxidants, are considered to be healthy for the human population. This may be true in some special situations such as, for instance, the prevention of Alzheimer's disease progression. However, recent epidemiological evidence has not supported the claim that antioxidant vitamins increase well-being and prolong life span. In fact, vitamin supplementation may be even detrimental and reduce life span. A new concept that we would like to put forward is that nutrients up-regulate the endogenous antioxidant defences. This is particularly true in the case of phytoestrogens for example, which bind to oestrogen receptors and eventually up-regulate the expression of antioxidant genes. In this review we discuss the pros and cons of antioxidant vitamin supplementation and also the possibility that the ingestion of some nutrients may be very effective in increasing antioxidant defences by up-regulating the activity of antioxidant enzymes which are normally present in the cell.

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Vanacker, H., J. Harbinson, J. Ruisch, T. L. W. Carver, and C. H. Foyer. "Antioxidant defences of the apoplast." Protoplasma 205, no. 1-4 (March 1998): 129–40. http://dx.doi.org/10.1007/bf01279303.

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Sevcikova, M., H. Modra, A. Slaninova, and Z. Svobodova. " Metals as a cause of oxidative stress in fish: a review." Veterinární Medicína 56, No. 11 (December 12, 2011): 537–46. http://dx.doi.org/10.17221/4272-vetmed.

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This review summarizes the current knowledge on the contribution of metals to the development of oxidative stress in fish. Metals are important inducers of oxidative stress in aquatic organisms, promoting formation of reactive oxygen species through two mechanisms. Redox active metals generate reactive oxygen species through redox cycling, while metals without redox potential impair antioxidant defences, especially that of thiol-containing antioxidants and enzymes. Elevated levels of reactive oxygen species lead to oxidative damage including lipid peroxidation, protein and DNA oxidation, and enzyme inactivation. Antioxidant defences include the enzyme system and low molecular weight antioxidants. Metal-binding proteins, such as ferritin, ceruloplasmin and metallothioneins, have special functions in the detoxification of toxic metals and also play a role in the metabolism and homeostasis of essential metals. Recent studies of metallothioneins as biomarkers indicate that quantitative analysis of mRNA expression of metallothionein genes can be appropriate in cases with elevated levels of metals and no evidence of oxidative damage in fish tissue. Components of the antioxidant defence are used as biochemical markers of oxidative stress. These markers may be manifested differently in the field than in results found in laboratory studies. A complex approach should be taken in field studies of metal contamination of the aquatic environment.  

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Felicijan, Mateja, Metka Novak, Nada Kraševec, and Andreja Urbanek Krajnc. "Antioxidant defences of Norway spruce bark against bark beetles and its associated blue-stain fungus." Agricultura 12, no. 1-2 (December 1, 2015): 9–18. http://dx.doi.org/10.1515/agricultura-2016-0002.

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Abstract Bark beetles and their fungal associates are integral parts of forest ecosystems, the European spruce bark beetle (Ips typographus Linnaeus, 1758) and the associated pathogenic blue stain fungus Ceratocystis polonica (SIEM.) C. MOREAU, are the most devastating pests regarding Norway spruce [Picea abies (L.) H. KARST.]. Bark beetles commonly inhabit weakened and felled trees as well as vital trees. They cause physiological disorders in trees by destroying a phloem and cambium or interrupt the transpiration -ow in the xylem. Conifers have a wide range of effective defence mechanisms that are based on the inner bark anatomy and physiological state of the tree. The basic function of bark defences is to protect the nutrient-and energy-rich phloem, the vital meristematic region of the vascular cambium, and the transpiration -ow in the sapwood. The main area of defence mechanisms is secondary phloem, which is physically and chemically protected by polyphenolic parenchyma (PP) cells, sclerenchyma, calcium oxalate crystals and resin ducts. Conifer trunk pest resistance includes constitutive, inducible defences and acquired resistance. Both constitutive and inducible defences may deter beetle invasion, impede fungal growth and close entrance wounds. During a successful attack, systemic acquired resistance (SAR) becomes effective and represents a third defence strategy. It gradually develops throughout the plant and provides a systemic change within the whole tree’s metabolism, which is maintained over a longer period of time. The broad range of defence mechanisms that contribute to the activation and utilisation of SAR, includes antioxidants and antioxidant enzymes, which are generally linked to the actions of reactive oxygen species (ROS). The presented review discusses the current knowledge on the antioxidant defence strategies of spruce inner bark against the bark beetle (Ips typographus) and associated blue stain fungus (Ceratocystis polonica).

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Chainy, Gagan Bihari Nityananda, Biswaranjan Paital, and Jagneswar Dandapat. "An Overview of Seasonal Changes in Oxidative Stress and Antioxidant Defence Parameters in Some Invertebrate and Vertebrate Species." Scientifica 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/6126570.

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Antioxidant defence system, a highly conserved biochemical mechanism, protects organisms from harmful effects of reactive oxygen species (ROS), a by-product of metabolism. Both invertebrates and vertebrates are unable to modify environmental physical factors such as photoperiod, temperature, salinity, humidity, oxygen content, and food availability as per their requirement. Therefore, they have evolved mechanisms to modulate their metabolic pathways to cope their physiology with changing environmental challenges for survival. Antioxidant defences are one of such biochemical mechanisms. At low concentration, ROS regulates several physiological processes, whereas at higher concentration they are toxic to organisms because they impair cellular functions by oxidizing biomolecules. Seasonal changes in antioxidant defences make species able to maintain their correct ROS titre to take various physiological functions such as hibernation, aestivation, migration, and reproduction against changing environmental physical parameters. In this paper, we have compiled information available in the literature on seasonal variation in antioxidant defence system in various species of invertebrates and vertebrates. The primary objective was to understand the relationship between varied biological phenomena seen in different animal species and conserved antioxidant defence system with respect to seasons.

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Kusumaningrum, Amalia Ratna. "Antioxidant supplementation during in vitro maturation." Journal of Midwifery 4, no. 2 (June 7, 2020): 1. http://dx.doi.org/10.25077/jom.4.2.1-7.2019.

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During in vitro maturation (IVM), oocytes are exposed to different situations from in vivo which may cause oxidative stress. Supplementation of antioxidants to the culture media is effective in as antioxidant defences against reactive oxygen species (ROS). Antioxidant is safe, it has some side effects. This is reviewed in this paper. Studies reported, supplementation antioxidant with different dose showed different effects. Double-edged eﬀects of exogenous antioxidants on cellular responses during in vitro maturation depending potentially on their concentrations. Physiologic doses leading to beneficial eﬀects whereas high doses may result in harmful eﬀects.

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Surai, Kochish, Fisinin, and Kidd. "Antioxidant Defence Systems and Oxidative Stress in Poultry Biology: An Update." Antioxidants 8, no. 7 (July 22, 2019): 235. http://dx.doi.org/10.3390/antiox8070235.

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Poultry in commercial settings are exposed to a range of stressors. A growing body of information clearly indicates that excess ROS/RNS production and oxidative stress are major detrimental consequences of the most common commercial stressors in poultry production. During evolution, antioxidant defence systems were developed in poultry to survive in an oxygenated atmosphere. They include a complex network of internally synthesised (e.g., antioxidant enzymes, (glutathione) GSH, (coenzyme Q) CoQ) and externally supplied (vitamin E, carotenoids, etc.) antioxidants. In fact, all antioxidants in the body work cooperatively as a team to maintain optimal redox balance in the cell/body. This balance is a key element in providing the necessary conditions for cell signalling, a vital process for regulation of the expression of various genes, stress adaptation and homeostasis maintenance in the body. Since ROS/RNS are considered to be important signalling molecules, their concentration is strictly regulated by the antioxidant defence network in conjunction with various transcription factors and vitagenes. In fact, activation of vitagenes via such transcription factors as Nrf2 leads to an additional synthesis of an array of protective molecules which can deal with increased ROS/RNS production. Therefore, it is a challenging task to develop a system of optimal antioxidant supplementation to help growing/productive birds maintain effective antioxidant defences and redox balance in the body. On the one hand, antioxidants, such as vitamin E, or minerals (e.g., Se, Mn, Cu and Zn) are a compulsory part of the commercial pre-mixes for poultry, and, in most cases, are adequate to meet the physiological requirements in these elements. On the other hand, due to the aforementioned commercially relevant stressors, there is a need for additional support for the antioxidant system in poultry. This new direction in improving antioxidant defences for poultry in stress conditions is related to an opportunity to activate a range of vitagenes (via Nrf2-related mechanisms: superoxide dismutase, SOD; heme oxygenase-1, HO-1; GSH and thioredoxin, or other mechanisms: Heat shock protein (HSP)/heat shock factor (HSP), sirtuins, etc.) to maximise internal AO protection and redox balance maintenance. Therefore, the development of vitagene-regulating nutritional supplements is on the agenda of many commercial companies worldwide.

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Lenaz, G., C. Bovina, G. Formiggini, and G. Parenti Castelli. "Mitochondria, oxidative stress, and antioxidant defences." Acta Biochimica Polonica 46, no. 1 (March 31, 1999): 1–21. http://dx.doi.org/10.18388/abp.1999_4179.

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Mitochondria are strongly involved in production of reactive oxygen species, considered today as the main pathogenic agent of many diseases. A vicious circle of oxidative stress and damage to cellular structures can lead to either cell death by apoptosis or to a cellular energetic decline and ageing. The early involvement of mitochondria in apoptosis includes expression of pro-apoptotic factors, release of cytochrome c from the inter-membrane space and opening of the permeability transition pore: cytochrome c release appears to precede pore opening. The mitochondrial theory of ageing considers somatic mutations (deletions) of mitochondrial DNA induced by oxygen radicals as the primary cause of energy decline; experimentally, Complex I appears to be mostly affected. We have developed the Pasteur effect (enhancement of lactate production by mitochondrial inhibition) as a bio-marker of mitochondrial bioenergetics in human platelets, and found it to be decreased in aged individuals. Cells counteract oxidative stress by antioxidants; among lipophilic antioxidants coenzyme Q is the only one of endogenous biosynthesis; exogenous coenzyme Q, however, may protect cells from oxidative stress in vivo.

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Lenaz, Giorgio, Marika Cavazzoni, Maria Luisa Genova, Marilena D'Aurelio, Milena Merlo Pich, Francesco Pallotti, Gabriella Formiggini, Mario Marchetti, Giovanna Parenti Castelli, and Carla Bovina. "Oxidative stress, antioxidant defences and aging." BioFactors 8, no. 3-4 (1998): 195–204. http://dx.doi.org/10.1002/biof.5520080305.

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Colominas-Ciuró, R., M. Bertellotti, VL D’Amico, E. Carabajal, J. Benzal, V. Vidal, M. Motas, M. Santos, N. Coria, and A. Barbosa. "Diet, antioxidants and oxidative status in pygoscelid penguins." Marine Ecology Progress Series 665 (April 29, 2021): 201–16. http://dx.doi.org/10.3354/meps13651.

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Ecologically similar marine species inhabiting the same areas compete for food resources. Such competition is reduced by resource-partitioning strategies that may affect physiology. For instance, diet and feeding strategies may affect the antioxidant defences or the production of reactive oxygen species. Oxidative stress is defined as the imbalance between pro-oxidants and antioxidant defences. If such an imbalance favours the former, this can lead to oxidative damage, and oxidative stress increases. However, to our knowledge, how free-ranging animals adjust their oxidative status in relation to their foraging habitats, diet and dietary antioxidants has not yet been studied. Penguins are an interesting biological model for such a comparison because their diet, based on krill, fish and/or cephalopods, presents strong variation in dietary antioxidant content. We therefore examined trophic level (δ15N), foraging habitat (δ13C), dietary antioxidants (retinol, α-tocopherol and astaxanthin) and oxidative status (plasma non-enzymatic antioxidant capacity and oxidative damage) in pygoscelid penguins (chinstrap Pygoscelis antarcticus, gentoo P. papua and Adélie P. adeliae) breeding in Antarctica. We found interspecific differences in all variables analysed except α-tocopherol. Gentoo penguins exploited more cephalopods and fish in coastal and benthic habitats, Adélies showed an intermediate position, whereas chinstraps foraged more on krill and fish in pelagic waters. Dietary antioxidant levels showed specific patterns resulting in relationships with prey items. However, we did not find any clear relationships between dietary antioxidants and species-specific antioxidant capacity, suggesting the importance of endogenously produced antioxidants. Oxidative status appeared to be differently related to foraging strategy and antioxidant capacity in each species.

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Drury, Josephine A., Julie A. Nycyk, Malcolm Baines, and Richard W. I. Cooke. "Does Total Antioxidant Status Relate to Outcome in Very Preterm Infants?" Clinical Science 94, no. 2 (February 1, 1998): 197–201. http://dx.doi.org/10.1042/cs0940197.

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1. In healthy humans, a balance exists between oxygen-derived free-radical production and their removal by antioxidants. In preterm infants inadequate antioxidant defences may contribute to the pathogenesis of some of the complications of prematurity. 2. Plasma total antioxidant status and malondialdehyde concentration were measured during the first 11 days of life in 25 infants to determine whether increased lipid peroxidation is associated with low extracellular antioxidant status. In a second group of infants, total antioxidant status was quantified within 12 h of birth, and subsequently on days 4 and 10 to investigate the hypothesis that adverse neonatal outcome is associated with low antioxidant status. 3. There may be a weak negative correlation between the total antioxidant status of infants and the lipid peroxidation marker malondialdehyde in plasma (r = −0.24, P = 0.056, n = 89) during the first 11 days of life. In the second group of infants, total antioxidant status was found to be significantly related to plasma urate and bilirubin levels, but not to adverse neonatal outcomes such as chronic lung disease, intraventricular haemorrhage, retinopathy of prematurity or death. 4. If adverse neonatal outcomes are due to inadequate antioxidant defences, these are likely to be intracellular or localized rather than general extracellular deficiencies.

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Roveri, A., R. Bruni, A. Baritussio, M. Coassin, M. Benevento, M. Maiorino, and F. Ursini. "Antioxidant Defences of Rabbit Alveolar Lining Fluid." Respiration 55, no. 1 (1989): 68–73. http://dx.doi.org/10.1159/000195754.

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Filho, Danilo Wilhelm, Cecilia Giulivi, and Alberto Boveris. "Antioxidant defences in marine fish—I. Teleosts." Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology 106, no. 2 (October 1993): 409–13. http://dx.doi.org/10.1016/0742-8413(93)90154-d.

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Filho, Danilo Wilhelm, and Alberto Boveris. "Antioxidant defences in marine fish—II. Elasmobranchs." Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology 106, no. 2 (October 1993): 415–18. http://dx.doi.org/10.1016/0742-8413(93)90155-e.

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Gariballa, SE, and AJ Sinclair. "Cerebrovascular disease and oxidative stress." Reviews in Clinical Gerontology 9, no. 3 (August 1999): 197–206. http://dx.doi.org/10.1017/s0959259899009314.

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There is strong indirect evidence that free radical production appears to be an important mechanism of brain injury after exposure to ischaemia and reperfusion. Although significant brain damage occurs during an ischaemic episode, new cerebral damage can occur after reperfusion. One proposed mechanism for the brain damage that occurs during reperfusion involves generation of free radicals. Body defences against free radicals depends on the balance between free radical generation and the antioxidant protective defence system. Many of these protective antioxidants are essential nutrients or have essential nutrients as part of their molecule that has to be obtained from diet.

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Beaulieu, Michaël, Ines Bischofberger, Isabel Lorenz, Lucie Scheelen, and Klaus Fischer. "Reproducing butterflies do not increase intake of antioxidants when they could benefit from them." Biology Letters 12, no. 2 (February 2016): 20150941. http://dx.doi.org/10.1098/rsbl.2015.0941.

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The significance of dietary antioxidants may be limited by the ability of animals to exploit them. However, past studies have focused on the effects of dietary antioxidants after ‘antioxidant forced-feeding’, and have overlooked spontaneous antioxidant intake. Here, we found that reproducing female Bicyclus anynana butterflies had higher antioxidant defences and enhanced fecundity when forced to consume antioxidants (polyphenols). Interestingly, these positive effects were not constant across the oviposition period. When given the choice between food resources with and without antioxidants, reproducing butterflies did not target antioxidants when they could have benefited the most from them. Moreover, they did not consume more antioxidants than non-reproducing butterflies. These results emphasize that, despite potential positive effects of dietary antioxidants, the ability of animals to exploit them is likely to restrict their ecological significance.

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Fraternale, Daniele, Roberta De Bellis, Cinzia Calcabrini, Lucia Potenza, Luigi Cucchiarini, Umberto Mancini, Marina Dachà, and Donata Ricci. "Aqueous Extract from Vitis vinifera Tendrils is Able to Enrich Keratinocyte Antioxidant Defences." Natural Product Communications 6, no. 9 (September 2011): 1934578X1100600. http://dx.doi.org/10.1177/1934578x1100600925.

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An aqueous extract of V. vinifera L. tendrils was evaluated for its ability to enrich the antioxidant capacity of cultured cells. The long-time antioxidant capability of the extract was measured by in vitro chemical methods, and its influence on reduced glutathione levels and plasma membrane oxido reductase activity was determined in cultured human keratinocytes (NCTC 2544). Keratinocytes are cells normally exposed to oxidative stress, and for this reason adequately equipped with antioxidant defences. However, it has long been suggested that exogenous antioxidants may play an important role in minimizing the adverse effects of oxidative stress on skin. We demonstrated that V. vinifera tendril aqueous extract was able to increase, in a time- and dose-dependent manner, the reduced glutathione concentration and activity of trans plasma membrane oxido reductase as an indirect evaluation of the intracellular redox status of the cells demonstrating a relevant antioxidant activity of this phytocomplex.

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Gopalakrishnan, Singaram, Fang-Yi Chen, Harikrishnan Thilagam, Kun Qiao, Wan-Fang Xu, and Ke-Jian Wang. "Modulation and Interaction of Immune-Associated Parameters with Antioxidant in the Immunocytes of CrabScylla paramamosainChallenged with Lipopolysaccharides." Evidence-Based Complementary and Alternative Medicine 2011 (2011): 1–8. http://dx.doi.org/10.1155/2011/824962.

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Invertebrates are dependent on cellular and humoral immune defences against microbial infection.Scylla paramamosainis an important commercial species, but the fundamental knowledge on its immune defense related to the antioxidant and immune-associated reactions is still lacking. The study was to differentiate the responses of immune-associated parameters of haemolymph components inS. paramamosainwhen challenged with bacterial lipopolysaccharides (LPSs). The immunostimulating effects of LPS in crab by triggering various immune parameters (phagocytosis, lysozyme, antibacterial activity, phenoloxidase, and the generation of superoxide and nitric oxide) were investigated. Results showed that the generation of free radicals, phenoloxidase, lysozyme and antibacterial activities was significantly increased through the exposure periods. Conversely, total hemocyte count and lysosomal membrane stability decreased significantly as the exposure period extended to 96 h. The relationship between the antioxidant enzymes and immune reactions due to LPS was highly significant. In addition, ROS production was positively correlated with antioxidant showing immediate response of antioxidant defense to the oxyradicals generated. Overall, the study indicated that nonspecific immune components in hemocytes of crab showed active response to the LPS stimulation, and their responses suggested that many immune-associated parameters could be modulated and interrelated with the influence of antioxidants in crustaceans.

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Rana, Mashidur, Sudhir C. Roy, and Bannur C. Divyashree. "Sperm antioxidant defences decrease during epididymal transit from caput to cauda in parallel with increases in epididymal fluid in the goat (Capra hircus)." Reproduction, Fertility and Development 29, no. 9 (2017): 1708. http://dx.doi.org/10.1071/rd16269.

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The status of antioxidant defences of both spermatozoa and their associated fluids during epididymal transit from the caput to cauda have not been studied so far in any species. Herein we report for the first time that sperm antioxidant defences, namely Cu,Zn-superoxide dismutase (Cu,Zn-SOD) and catalase activity, decrease significantly (P < 0.05) from the caput to cauda during epididymal transit in parallel with increases in Cu,Zn-SOD, total SOD and total glutathione peroxidase (GPx) activity in the luminal fluid of the respective segments. However, levels of GPX1 and GPX3 in epididymal fluid did not change significantly from the caput to cauda. Catalase was detected for the first time in goat spermatozoa. A significantly higher total antioxidant capacity of caudal fluid than of the caput suggests a requirement for a rich antioxidant environment for the storage of spermatozoa. The retention of cytoplasmic droplets in most of the caudal spermatozoa confirmed that these droplets do not contribute to the increased antioxidant defences of cauda epididymidal fluid. Thus, the antioxidant defences of the spermatozoa and their associated epididymal fluid are modulated from the caput to cauda in a region-specific manner. This may be one of the compensatory mechanisms of epididymal fluid to scavenge any excess reactive oxygen species produced in the microenvironment of spermatozoa.

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Rajkumar S, Sambathkumar R, Gomathi Swaminathan, Vijayabaskaran M, and Kannan C. "Evaluation of Fluoride-Induced Neuro Degenerative Defences in Cyclea Peltata Lam Roots." International Journal of Research in Pharmaceutical Sciences 11, no. 4 (December 21, 2020): 8034–41. http://dx.doi.org/10.26452/ijrps.v11i4.4756.

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Many diseases have become easier to diagnose and treat as a result of advancements in medical science and technology, but strokes, which have multiple etiologies and mechanisms, continue to be difficult to treat. Synthetic drugs are notorious for causing a slew of unavoidable side effects. Herbal drugs have a wide range of mechanisms of action and are typically free of side effects, making them excellent alternatives to synthetic drugs for stroke treatment. Cyclea peltata (Lam) Hook f. Thoms roots were studied for their neuroprotective properties against fluoride-induced neurodegeneration in rats. The rat brain homogenate was investigated for the levels of non-enzymatic antioxidants like norepinephrine and serotonin to analyse the health of the brain. Both the hormones norepinephrine and serotonin levels were restored due to the treatment with ethanol extract of the plant. The antioxidant enzyme levels like SOD, CAT, GSH and GPx in the rat brain were estimated, and the results were similar to the non-enzymatic levels. The elevation of antioxidant enzymes indicates that the extract had an antioxidant mechanism that is responsible to help in the prevention of neurodegeneration of rats. In the brain tissues treated with Cyclea peltata extract, there was a significant increase in antioxidant enzymes and a reduction in lipid peroxidation, confirming the antioxidant mechanisms responsible for stroke prevention in extract-treated groups. The root extract of Cyclea peltata was found to show a reasonable inhibitory effect on neurodegeneration when delivered at a dose of 200mg/kg.

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Fangyu, Wang, Yang Hongsheng Yang, Wang Xiaoyu, Xing Kun, and Gao Fei. "Antioxidant enzymes in sea cucumber Apostichopus japonicus (Selenka) during aestivation." Journal of the Marine Biological Association of the United Kingdom 91, no. 1 (July 5, 2010): 209–14. http://dx.doi.org/10.1017/s0025315410000779.

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To evaluate the effect of antioxidant defence in coelomic fluid of sea cucumber, Apostichopus japonicus in aestivation was studied in the field from July to November 2006 in Qingdao. During the sampling period, activities of superoxide dismutase and catalase increased significantly in August and November. Activities of glutathione reductase and glutathione decreased significantly in August and increased significantly in November and activities of Se-glutathione peroxidase increased significantly in August. There were no significant differences in total glutathione peroxidase. In relation to the water temperature in the field, it is known that the oxygen consumption rate dropped and antioxidant defence was enhanced in August. The structure and function of respiratory trees of A. japonicus were completely vivified as normal in November, and it is suggested that antioxidant defence was enhanced because of the sharp change of oxygen consumption. Data indicate that both enzymatic and metabolite antioxidant defences in sea cucumber are adaptable systems that are modulated during pre-aestivating stage and arousing stage.

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Benavídes, María P., Patricia L. Marconi, Susana M. Gallego, María E. Comba, and María L. Tomaro. "Relationship between antioxidant defence systems and salt tolerance in Solanum tuberosum." Functional Plant Biology 27, no. 3 (2000): 273. http://dx.doi.org/10.1071/pp99138.

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A relationship between the antioxidant defence system and salt tolerance in two clones of potato (Solanum tuberosum L.) differing in salt sensitivity was studied. The antioxidant defence system of the sensitive clone responded differently to 100 and 150 mM NaCl. At 100 mM NaCl, growth, dehydroascorbate reductase and catalase activities remained unaltered, but chlorophyll and reduced glutathione content decreased (23% and 35%, respectively), while ascorbate content and superoxide dismutase activity were increased 34% and 63%, with respect to the control (0 mM NaCl). The superoxide dismutase increment was higher under 150 mM NaCl treatment, while a general decrease (except for dehydroascorbate reductase and catalase activities) in all the antioxidant parameters studied was observed in the sensitive clone. Reduced glutathione and ascorbate, the main antioxidant soluble defences, and all antioxidant enzymes (except catalase) were significantly elevated in the tolerant clone compared to the sensitive one when both were grown in the absence of NaCl. Under 100 and 150 mM NaCl treatments, no changes in the antioxidant stress parameters were detected in the tolerant clone. These results suggest a relationship between salt tolerance and the antioxidant defence system in the two clones.

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Camus, Lionel, Bjørn Gulliksen, Michael H. Depledge, and Malcolm B. Jones. "Polar bivalves are characterized by high antioxidant defences." Polar Research 24, no. 1-2 (July 2005): 111–18. http://dx.doi.org/10.3402/polar.v24i1.6257.

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Fernandes, Ana Sofia, Matilde Castro, and Nuno Guerreiro Oliveira. "Oxidative stress and antioxidant defences – a pedagogical review." Journal Biomedical and Biopharmaceutical Research 8, no. 1 (June 2011): 97–108. http://dx.doi.org/10.19277/bbr.8.1.8.

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Frank, Lee. "Development of the antioxidant defences in fetal life." Seminars in Neonatology 3, no. 3 (August 1998): 173–82. http://dx.doi.org/10.1016/s1084-2756(98)80002-x.

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Camus, Lionel, Bjørn Gulliksen, Michael H. Depledge, and Malcolm B. Jones. "Polar bivalves are characterized by high antioxidant defences." Polar Research 24, no. 1-2 (July 2004): 111–18. http://dx.doi.org/10.1111/j.1751-8369.2004.tb00018.x.

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Camus, Lionel, Bjørn Gulliksen, Michael H. Depledge, and Malcolm B. Jones. "Polar bivalves are characterized by high antioxidant defences." Polar Research 24, no. 1-2 (July 2005): 111–18. http://dx.doi.org/10.1111/j.1751-8369.2005.tb00144.x.

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Tappia, Paramjit S., Kerry L. Troughton, Simon C. Langley-Evans, and Robert F. Grimble. "Cigarette Smoking Influences Cytokine Production and Antioxidant Defences." Clinical Science 88, no. 4 (April 1, 1995): 485–89. http://dx.doi.org/10.1042/cs0880485.

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1. Smoking exerts an inflammatory stimulus on lung macrophages, and smokers generally have low intakes of antioxidant micronutrients. This study was performed to investigate the relationship between whole-blood tumour necrosis factor production, plasma interleukin-6 and acute-phase protein concentration and antioxidant vitamins in smokers and non-smokers. 2. Measurement of tumour necrosis factor was conducted in whole blood stimulated with endotoxin (lipopolysaccharide), and interleukin-6 concentrations were measured in the plasma of smokers and non-smokers. Enzyme and dietary antioxidant concentrations and acute-phase proteins were determined in the two groups. 3. Tumour necrosis factor production and plasma interleukin-6 concentrations were 38% (P = 0.01) and 16% (P = 0.07) greater, respectively, in smokers than in non-smokers. Plasma vitamin A and E concentrations were unaffected by smoking; however, a 21% lower plasma vitamin C (P = 0.04) concentration was observed in smokers, than in non-smokers despite a similar intake of this vitamin by the two groups. 4. Concentrations of the acute-phase proteins α1-acid glycoprotein, caeruloplasmin and α2-macroglobulin were increased in the plasma of smokers compared with non-smokers by 39%, 28% and 12% respectively (P < 0.01). Our studies indicate that smokers have a compromised antioxidant status and elevated concentrations of tumour necrosis factor and interleukin-6 as a consequence of smoking. 5. These observations may provide some insight into the biological mechanisms underlying the pathology associated with smoking.

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Buffinton, Gary D., and William F. Doe. "Depleted mucosal antioxidant defences in inflammatory bowel disease." Free Radical Biology and Medicine 19, no. 6 (December 1995): 911–18. http://dx.doi.org/10.1016/0891-5849(95)94362-h.

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Bolton, Colin H., Alison A. Leaf, and Leonie G. Downs. "Antioxidant defences and lipid peroxidation in preterm infants." Biochemical Society Transactions 25, no. 3 (August 1, 1997): 522S. http://dx.doi.org/10.1042/bst025522s.

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Oso, Babatunde Joseph, Olufunke Temiloluwa Oso, and Adenike Temidayo Oladiji. "Redox balance: A probable target in the management of immune dysfunction." Brazilian Journal of Biological Sciences 5, no. 10 (2018): 259–64. http://dx.doi.org/10.21472/bjbs.051006.

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Activation of cell-mediated immune is usually interconnected with the generation of oxidative species. The objective of this review was to concisely discuss the interplay between redox balance and immune functions. A qualitative review of peer reviewed papers published in journals and other publications was conducted. The review showed that cellular oxidants which act as signalling molecules could drive biological responses such as those that modulate the productions of pro- and anti-inflammatory cytokines and immune function. Moreover, beneficial effects of these cellular oxidants could be maintained by an array of defence pathways which include antioxidants, proteins and antioxidant enzymes. When there is an imbalance between increased oxidative species and suppressed antioxidant defences, oxidative stress and associated secondary complications may occur. Therefore, maintaining the redox homeostasis and immune responses through modulation of redox-sensitive inflammatory pathways may offer anticipative possibilities for management of diseases associated with dysfunctional redox homeostasis and immune disorders.

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Berzosa, C., I. Cebrián, L. Fuentes-Broto, E. Gómez-Trullén, E. Piedrafita, E. Martínez-Ballarín, L. López-Pingarrón, R. J. Reiter, and J. J. García. "Acute Exercise Increases Plasma Total Antioxidant Status and Antioxidant Enzyme Activities in Untrained Men." Journal of Biomedicine and Biotechnology 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/540458.

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Antioxidant defences are essential for cellular redox regulation. Since free-radical production may be enhanced by physical activity, herein, we evaluated the effect of acute exercise on total antioxidant status (TAS) and the plasma activities of catalase, glutathione reductase, glutathione peroxidase, and superoxide dismutase and its possible relation to oxidative stress resulting from exercise. Healthy untrained male subjects () performed three cycloergometric tests, including maximal and submaximal episodes. Venous blood samples were collected before and immediately after each different exercise. TAS and enzyme activities were assessed by spectrophotometry. An increase of the antioxidant enzyme activities in plasma was detected after both maximal and submaximal exercise periods. Moreover, under our experimental conditions, exercise also led to an augmentation of TAS levels. These findings are consistent with the idea that acute exercise may play a beneficial role because of its ability to increase antioxidant defense mechanisms through a redox sensitive pathway.

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P, Sushma, Bindu Jacob, and Narendhirakannan R.T. "Evaluation Of Antioxidant And Cytotoxicity Properties Of Amygdalin Extracted From Prunus Dulcis." Kongunadu Research Journal 6, no. 2 (December 30, 2019): 8–12. http://dx.doi.org/10.26524/krj295.

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Free-radical reactions have been implicated in the pathology of many human diseases like atherosclerosis, ischemic heart disease, aging process, inflammation, diabetes, immuno-suppression,neurodegenerative disease etc. Radicals and other reactive oxygen species are formed constantly in the human body and are removed by the enzymatic and non-enzymatic antioxidant defence. The disturbance in ‘redox homeostasis’ that occurs when antioxidant defences are inadequate can damage lipids, proteins,carbohydrates and DNA. Drugs with multiple protective mechanisms, including antioxidant activity, may be one way of minimizing tissue injury. Phytochemicals with antioxidant property are naturally present in food are of great interest due to their beneficial effects on human health as they offer protection against oxidative deterioration. Amygdalin, also known as vitamin B17 is a cyanogenic glycoside found in several sources mainly in apples, pears, apricots, plums, peaches. Several reports claim amygdalin to be good chemopreventive agent, however these claims are not often backed by proper scientific evidence. Thus the present study is aimed to evaluate the therapeutic potential of amygdalin isolated from Prunus dulcis by studying its in vitro antioxidant and cytotoxic properties.Free-radical reactions have been implicated in the pathology of many human diseases like atherosclerosis, ischemic heart disease, aging process, inflammation, diabetes, immuno-suppression,neurodegenerative disease etc. Radicals and other reactive oxygen species are formed constantly in the human body and are removed by the enzymatic and non-enzymatic antioxidant defence. The disturbance in ‘redox homeostasis’ that occurs when antioxidant defences are inadequate can damage lipids, proteins,carbohydrates and DNA. Drugs with multiple protective mechanisms, including antioxidant activity, may be one way of minimizing tissue injury. Phytochemicals with antioxidant property are naturally present in food are of great interest due to their beneficial effects on human health as they offer protection against oxidative deterioration. Amygdalin, also known as vitamin B17 is a cyanogenic glycoside found in several sources mainly in apples, pears, apricots, plums, peaches. Several reports claim amygdalin to be good chemopreventive agent, however these claims are not often backed by proper scientific evidence. Thus the present study is aimed to evaluate the therapeutic potential of amygdalin isolated from Prunus dulcis by studying its in vitro antioxidant and cytotoxic properties.

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Mullineaux, Philip, Louise Ball, Carolina Escobar, Barbara Karpinska, Gary Creissen, and Stanislaw Karpinski. "Are diverse signalling pathways integrated in the regulation of Arabidopsis antioxidant defence gene expression in response to excess excitation energy?" Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 355, no. 1402 (October 29, 2000): 1531–40. http://dx.doi.org/10.1098/rstb.2000.0713.

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When low–light–grown Arabidopsis rosettes are partially exposed to excess light (EL), the unexposed leaves become acclimated to excess excitation energy (EEE) and consequent photo–oxidative stress. This phenomenon, termed systemic acquired acclimation (SAA), is associated with redox changes in the proximity of photosystem II, changes in foliar H 2 O 2 content and induction of antioxidant defences. The induction of extra–plastidial antioxidant systems is important in the protection of the chloroplast under EL conditions. A larger range of transcripts encoding different antioxidant defence enzymes may be induced in the systemically acclimated leaves and these include those encoded by the glutathione peroxidase ( GPX2 ) and glutathione–S–transferase ( GST ) genes, which are also highly induced in the hypersensitive response and associated systemic acquired resistance (SAR) in incompatible plantpathogen interactions. Furthermore, the expression of the SAR–inducible pathogenesis–related protein gene, PR2 , is enhanced in SAA leaves. Wounded leaf tissue also shows enhanced systemic induction of a cytosolic ascorbate peroxidase gene ( APX2 ) under EL conditions. These and other considerations, suggest H 2 O 2 and other reactive oxygen species (ROS) could be the common factor in signalling pathways for diverse environmental stresses. These effects may be mediated by changes in the level and redox state of the cellular glutathione pool. Mutants with constitutive expression of a normally EL–inducible APX2 gene have much reduced levels of foliar glutathione. The expression of APX1 and APX3 , encoding cytosolic and peroxisome–associated isoforms, respectively, are also under phytochrome–A–mediated control. The expression of these genes is tightly linked to the greening of plastids in etiolated seedlings. These data suggest that part of the developmental processes that bring about the acclimation of leaves to high light includes the configuration of antioxidant defences. Therefore, the linkage between immediate responses of leaves to EL, acclimation of chloroplasts to EEE and the subsequent changes to leaf form and function in high light could be mediated by the activity of foliar antioxidant defences and changes in the concentration of ROS.

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Marchioli, Roberto. "Vitamin E and Cardiovascular Disease." Thrombosis and Haemostasis 85, no. 05 (2001): 758–60. http://dx.doi.org/10.1055/s-0037-1615713.

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SummaryInterest in the use of antioxidants for the treatment of human disease, and in the role of dietary antioxidants in the prevention of disease development, has been sustained for at least two decades. Several anti-oxidant protective mechanisms exist and constitute a primary defensive system including enzymatic defences (glutathione peroxidase and superoxide dismutase, which depend on the presence of ions such as selenium, zinc, copper, and manganese) and naturally occurring vita-mins such as vitamin E, vitamin A, beta-carotene, and vitamin C. The most important natural antioxidants are vitamin E (in the form of α-, β-, γ-, and δ-tocopherols), beta-carotene, vitamin C and selenium (fundamental constituent of glutathione-peroxidase, i.e., an enzyme with antioxidant function). The first two are lipophilic substances whilst ascorbic acid is hydrophilic. Each antioxidant has a different important mechanism of action since oxidative damage can be caused by lipid- or water-soluble molecules. Lipid-soluble antioxidants are likely to be very important in preventing the peroxidation of low-density lipo-proteins (LDL) and this action could be paramount in the prevention of atherosclerosis. On the other hand, water-soluble antioxidants could be useful where a water-soluble oxidative stress occurs (e.g., inflammation). As lipophilic molecules, vitamin E and beta-carotene are incorporated into the LDL particle. Vitamin E is the main lipid-soluble chain-breaking antioxidant in plasma and tissues and converts the peroxyl-free radical to hydroperoxide, a less reactive radical. It acts as a first-line anti-oxidative defence of LDL particles, protecting unsatu-rated fatty acids from peroxidation. Beta-carotene is a carotenoid (precursor of vitamin A, pro-vitamin) that acts as scavenger of oxidising radicals such as singlet oxygen and is a second-line antioxidative defence of LDL cholesterol. Vitamin C (ascorbic acid) can react with singlet oxygen, superoxide, hydroxyl radicals, and is the first line of antioxi-dative defence in water-soluble compartments. In addition, it plays an important role in regenerating reduced -tocopherol.

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Pablo Hernando, Marcelo, Gabriela Fabiana Malanga, and Gustavo Adolfo Ferreyra. "Oxidative stress and antioxidant defences generated by solar UV in a Subantarctic marine phytoflagellate." Scientia Marina 69, S2 (December 30, 2005): 287–95. http://dx.doi.org/10.3989/scimar.2005.69s2287.

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Babin, A., C. Saciat, M. Teixeira, J. P. Troussard, S. Motreuil, J. Moreau, and Y. Moret. "Limiting immunopathology: Interaction between carotenoids and enzymatic antioxidant defences." Developmental & Comparative Immunology 49, no. 2 (April 2015): 278–81. http://dx.doi.org/10.1016/j.dci.2014.12.007.

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Mougeot, Francois, Jesuús Martínez-Padilla, Lucy M. I. Webster, Jonathan D. Blount, Lorenzo Pérez-Rodríguez, and Stuart B. Piertney. "Honest sexual signalling mediated by parasite and testosterone effects on oxidative balance." Proceedings of the Royal Society B: Biological Sciences 276, no. 1659 (December 2, 2008): 1093–100. http://dx.doi.org/10.1098/rspb.2008.1570.

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Extravagant ornaments evolved to advertise their bearers' quality, the honesty of the signal being ensured by the cost paid to produce or maintain it. The oxidation handicap hypothesis (OHH) proposes that a main cost of testosterone-dependent ornamentation is oxidative stress, a condition whereby the production of reactive oxygen and nitrogen species (ROS/RNS) overwhelms the capacity of antioxidant defences. ROS/RNS are unstable, very reactive by-products of normal metabolic processes that can cause extensive damage to key biomolecules (cellular proteins, lipids and DNA). Oxidative stress has been implicated in the aetiology of many diseases and could link ornamentation and genetic variation in fitness-related traits. We tested the OHH in a free-living bird, the red grouse. We show that elevated testosterone enhanced ornamentation and increased circulating antioxidant levels, but caused oxidative damage. Males with smaller ornaments suffered more oxidative damage than those with larger ornaments when forced to increase testosterone levels, consistent with a handicap mechanism. Parasites depleted antioxidant defences, caused oxidative damage and reduced ornament expression. Oxidative damage extent and the ability of males to increase antioxidant defences also explained the impacts of testosterone and parasites on ornamentation within treatment groups. Because oxidative stress is intimately linked to immune function, parasite resistance and fitness, it provides a reliable currency in the trade-off between individual health and ornamentation. The costs induced by oxidative stress can apply to a wide range of signals, which are testosterone-dependent or coloured by pigments with antioxidant properties.

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Wood, Lisa G., and Peter G. Gibson. "Reduced circulating antioxidant defences are associated with airway hyper-responsiveness, poor control and severe disease pattern in asthma." British Journal of Nutrition 103, no. 5 (October 29, 2009): 735–41. http://dx.doi.org/10.1017/s0007114509992376.

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Dietary antioxidants are important in protecting against oxidative stress. We have previously demonstrated that circulating dietary antioxidant levels are reduced in asthma. The present study examined the variation in dietary antioxidant levels in asthma, according to airway responsiveness, asthma control and clinical asthma pattern. Peripheral blood was collected from forty-one subjects with stable, persistent asthma. Airway responsiveness was assessed by hypertonic saline challenge. Asthma control was assessed using the Asthma Control Questionnaire. Clinical asthma pattern was determined using Global Initiative for Asthma (GINA) criteria. Whole-blood carotenoids (β-carotene, lycopene, α-carotene, β-cryptoxanthin, lutein/zeaxanthin) and tocopherols (α-, δ-, γ-tocopherol) were measured by HPLC. Plasma antioxidant potential (AOP) was determined by colorimetric assay (OxisResearch, Portland, OR, USA). Asthmatic subjects with airway hyper-responsiveness (AHR) had reduced levels of β-carotene and α-tocopherol compared with those without AHR. Subjects with uncontrolled asthma had low levels of AOP compared with those with controlled or partly controlled asthma. Subjects with a severe persistent clinical asthma pattern had reduced levels of α-tocopherol compared with those with a mild to moderate asthma pattern. We conclude that asthmatic subjects with AHR, uncontrolled asthma and a severe asthma pattern have impaired antioxidant defences and are thus most susceptible to the damaging effects of oxidative stress. This highlights the potential role for antioxidant supplementation in these subjects.

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Abdel Hamid, Enas R., Walaa H. Ali, Ashraf Azmy, Hanaa H. Ahmed, Lobna S. Sherif, and Maysa T. Saleh. "Oxidative Stress and Anti-Oxidant Markers in Premature Infants with Respiratory Distress Syndrome." Open Access Macedonian Journal of Medical Sciences 7, no. 17 (August 30, 2019): 2858–63. http://dx.doi.org/10.3889/oamjms.2019.534.

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BACKGROUND: Neonatal respiratory distress syndrome (RDS) caused by decreased surfactant and structural lung immaturity. The imbalance between oxidative status and antioxidant defence system was suggested to be an important trigger for lung affection with RDS. AIM: The goal of the current research was to elucidate the significance of the oxidant/ antioxidant status in the pathogenesis of RDS in preterm infants. PATIENTS AND METHODS: This controlled study included 31 preterm neonates with RDS and 36 healthy preterm neonates. Quantification level of oxidative stress biomarkers; malondialdehyde (MDA) & hydrogen peroxide (H2O2) along with antioxidant enzymes activity; catalase (CAT) & superoxide dismutase (SOD) in plasma of healthy premature neonates compared with those with RDS. RESULTS: status of oxidative stress markers (MDA & H2O2) showed a significant increase with decreased levels of antioxidant enzymes activity (CAT & SOD) in neonates with RDS when compared to healthy prematures. CONCLUSION: The results obtained in this study indicate that the increased oxidative stress accompanied by reduced antioxidant defences may play a significant role in the pathogenesis of respiratory distress in preterm newborns.

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Jiang, Jun, Xiao-Yun Wu, Xiao-Qiu Zhou, Lin Feng, Yang Liu, Wei-Dan Jiang, Pei Wu, and Ye Zhao. "Glutamate ameliorates copper-induced oxidative injury by regulating antioxidant defences in fish intestine." British Journal of Nutrition 116, no. 1 (May 17, 2016): 70–79. http://dx.doi.org/10.1017/s0007114516001732.

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AbstractThe objective of this study was to determine the protective effect of glutamate (Glu) in Cu-induced oxidative injury in fish intestine in vivo and enterocytes in vitro. The results indicated that exposure to 6 mg/l Cu for 72 h induced the production of reactive oxygen species, thereby increasing protein oxidation and lipid peroxidation in enterocytes of grass carp in vitro. Cells exposed to Cu alone resulted in a significant increase in lactate dehydrogenase release, which is accompanied by depletions of antioxidants, including total superoxide dismutase (T-SOD), glutathione S-transferase (GST), glutathione reductase (GR), anti-superoxide anion (ASA), anti-hydroxy radical (AHR) activities and GSH content. Pre-treatment with Glu remarkably prevented the toxic effects of Cu on the T-SOD, GST, GR, AHR, and ASA activities and GSH content in enterocytes. However, Cu induced an adaptive increase in the activities of catalase and glutathione peroxidase (GPx). Glu supplementation further increased GPx activity in enterocytes. Interestingly, the experiment in vivo showed that Glu pre-supplementation significantly elevated SOD, GPx, GST, GR, ASA and AHR activities, as well as GSH content. Further results showed that pre-treatment with Glu could alleviate Cu-induced oxidative injury by elevating antioxidant enzyme activities through regulating the expression of NF-E2-related nuclear factor 2 (Nrf2) mRNA. Together, these results indicated that Glu could attenuate Cu-induced cellular oxidative damage in fish intestine, likely mediated through Nrf2 signalling pathways regulating mRNA expressions of antioxidant enzyme genes and synthesis of GSH.

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Fletcher, Louise A., Robert G. Fassett, Ross S. Richards, and Jeff S. Coombes. "Cyclosporine A induced changes to plasma and erythrocyte antioxidant defences." Redox Report 10, no. 1 (February 2005): 2–8. http://dx.doi.org/10.1179/135100005x21543.

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ITURBE-ORMAETXE, I., J. F. MORAN, C. ARRESE-IGOR, Y. GOGORCENA, R. V. KLUCAS, and M. BECANA. "Activated oxygen and antioxidant defences in iron-deficient pea plants." Plant, Cell and Environment 18, no. 4 (April 1995): 421–29. http://dx.doi.org/10.1111/j.1365-3040.1995.tb00376.x.

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Esserti, Siham, Amal Smaili, Kacem Makroum, Malika Belfaiza, Lalla Aicha Rifai, Tayeb Koussa, Imane Kasmi, and Mohamed Faize. "Priming of Nicotiana benthamiana antioxidant defences using brown seaweed extracts." Journal of Phytopathology 166, no. 2 (December 2, 2017): 86–94. http://dx.doi.org/10.1111/jph.12664.

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Song, Miryoung, Maroof Husain, Jessica Jones-Carson, Lin Liu, Calvin A. Henard, and Andrés Vázquez-Torres. "Low-molecular-weight thiol-dependent antioxidant and antinitrosative defences inSalmonellapathogenesis." Molecular Microbiology 87, no. 3 (December 21, 2012): 609–22. http://dx.doi.org/10.1111/mmi.12119.

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Cote, J., E. Arnoux, G. Sorci, M. Gaillard, and B. Faivre. "Age-dependent allocation of carotenoids to coloration versus antioxidant defences." Journal of Experimental Biology 213, no. 2 (December 28, 2009): 271–77. http://dx.doi.org/10.1242/jeb.035188.

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Carvalho, Félix, Eduarda Fernandes, Fernando Remião, and Maria Lourdes Bastos. "Effect of d -amphetamine repeated administration on rat antioxidant defences." Archives of Toxicology 73, no. 2 (April 21, 1999): 83–89. http://dx.doi.org/10.1007/s002040050591.

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Cheng, Lin, Pingnan Sun, Xiaoling Xie, Dongmei Sun, Qi Zhou, Shaozhe Yang, Qingdong Xie, and Xiaoling Zhou. "Hepatitis B virus surface protein induces oxidative stress by increasing peroxides and inhibiting antioxidant defences in human spermatozoa." Reproduction, Fertility and Development 32, no. 14 (2020): 1180. http://dx.doi.org/10.1071/rd20130.

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Hepatitis B virus (HBV) infection may affect sperm motility in patients with HBV. HBV surface protein (HBs) decreases mitochondrial membrane potential, impairs motility and induces apoptotic-like changes in human spermatozoa. However, little is known about how human spermatozoa respond to reactive oxygen species (ROS; mainly peroxides) induced by HBs. In this study, HBs induced supraphysiological ROS levels in human spermatozoa and reduced the formation of 2-cell embryos (obtained from hamster oocytes and human spermatozoa). HBs induced a pre-apoptotic status in human spermatozoa, as well as antioxidant defences by increasing glutathione peroxidase 4 (GPX4) and peroxiredoxin 5 (PRDX5) levels. These results highlight the molecular mechanism responsible for the oxidative stress in human spermatozoa exposed to HBV and the antioxidant defence response involving GPX4 and PRDX5.

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Grundman, Michael, and Patrick Delaney. "Antioxidant strategies for Alzheimer's disease." Proceedings of the Nutrition Society 61, no. 2 (May 2002): 191–202. http://dx.doi.org/10.1079/pns2002146.

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Oxidative damage is present within the brains of patients with Alzheimer's disease (AD), and is observed within every class of biomolecule, including nucleic acids, proteins, lipids and carbohydrates. Oxidative injury may develop secondary to excessive oxidative stress resulting from β-amyloid-induced free radicals, mitochondrial abnormalities, inadequate energy supply, inflammation or altered antioxidant defences. Treatment with antioxidants is a promising approach for slowing disease progression to the extent that oxidative damage may be responsible for the cognitive and functional decline observed in AD. Although not a uniformly consistent observation, a number of epidemiological studies have found a link between antioxidant intake and a reduced incidence of dementia, AD and cognitive decline in elderly populations. In AD clinical trials molecules with antioxidant properties such as vitamin E andGinkgo bilobaextract have shown modest benefit. A clinical trial with vitamin E is currently ongoing to determine if it can delay progression to AD in individuals with mild cognitive impairment. Combinations of antioxidants might be of even greater potential benefit for AD, especially if the agents worked in different cellular compartments or had complementary activity (e.g. vitamins E, C and ubiquinone). Naturally-occurring compounds with antioxidant capacity are available and widely marketed (e.g. vitamin C, ubiquinone, lipoic acid, β-carotene, creatine, melatonin, curcumin) and synthetic compounds are under development by industry. Nevertheless, the clinical value of these agents for AD prevention and treatment is ambiguous, and will remain so until properly designed human trials have been performed.

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Journal articles on the topic 'Antioxidant defences'

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