Antioxidants And Antioxidant Enzymes In Higher ...
The aims of our study were to assess whether the increased oxidative stress in inflamed joints is reflected by serum lipid peroxidation and also to check alterations in the levels of extracellular antioxidants and antioxidant enzyme activities in patients with rheumatoid arthritis. Serum malondialdehyde and ceruloplasmin levels and the activity of CuZn superoxide dismutase were higher, while transferrin levels and the activities of glutathione peroxidase and catalase were lower in patients (n = 37) than in healthy controls (n = 30). Disease activity score correlated positively with serum malondialdehyde level and CuZn superoxide dismutase activity. Probably, superoxide radicals in serum could be dismutated to produce hydrogen peroxide by increased CuZn superoxide dismutase activity, but hydrogen peroxide could not have been detoxified due to decreased activities of serum glutathione peroxidase and catalase. Hydrogen peroxide possibly converted to hydroxyl radical by iron due to lower transferrin level might have led to increased serum lipid peroxidation in patients with rheumatoid arthritis.
Antioxidants and Antioxidant Enzymes in Higher ...
Free radicals and related species have attracted a great deal of attention in recent years. They are mainly derived from oxygen (reactive oxygen species/ROS) and nitrogen (reactive nitrogen species/RNS), and are generated in our body by various endogenous systems, exposure to different physicochemical conditions or pathophysiological states. Free radicals can adversely alter lipids, proteins and DNA and have been implicated in aging and a number of human diseases. Lipids are highly prone to free radical damage resulting in lipid peroxidation that can lead to adverse alterations. Free radical damage to protein can result in loss of enzyme activity. Damage caused to DNA, can result in mutagenesis and carcinogenesis. Redox signaling is a major area of free radical research that is attracting attention. Nature has endowed us with protective antioxidant mechanisms- superoxide dismutase (SOD), catalase, glutathione, glutathione peroxidases and reductase, vitamin E (tocopherols and tocotrienols), vitamin C etc., apart from many dietary components. There are epidemiological evidences correlating higher intake of components/ foods with antioxidant abilities to lower incidence of various human morbidities or mortalities. Current research reveals the different potential applications of antioxidant/free radical manipulations in prevention or control of disease. Natural products from dietary components such as Indian spices and medicinal plants are known to possess antioxidant activity. Newer and future approaches include gene therapy to produce more antioxidants in the body, genetically engineered plant products with higher level of antioxidants, synthetic antioxidant enzymes (SOD mimics), novel biomolecules and the use of functional foods enriched with antioxidants.
The first line of defense is the preventive antioxidants, which suppress the formation of free radicals. Although the precise mechanism and site of radical formation in vivo are not well elucidated yet, the metal-induced decompositions of hydroperoxides and hydrogen peroxide must be one of the important sources. To suppress such reactions, some antioxidants reduce hydroperoxides and hydrogen peroxide beforehand to alcohols and water, respectively, without generation of free radicals and some proteins sequester metal ions.
The second line of defense is the antioxidants that scavenge the active radicals to suppress chain initiation and/or break the chain propagation reactions. Various endogenous radical-scavenging antioxidants are known: some are hydrophilic and others are lipophilic. Vitamin C, uric acid, bilirubin, albumin, and thiols are hydrophilic, radical-scavenging antioxidants, while vitamin E and ubiquinol are lipophilic radical-scavenging antioxidants. Vitamin E is accepted as the most potent radical-scavenging lipophilic antioxidant.
The third line of defense is the repair and de novo antioxidants. The proteolytic enzymes, proteinases, proteases, and peptidases, present in the cytosol and in the mitochondria of mammalian cells, recognize, degrade, and remove oxidatively modified proteins and prevent the accumulation of oxidized proteins.
Abstract:Global climate change and associated adverse abiotic stress conditions, such as drought, salinity, heavy metals, waterlogging, extreme temperatures, oxygen deprivation, etc., greatly influence plant growth and development, ultimately affecting crop yield and quality, as well as agricultural sustainability in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS), during various processes associated with abiotic stress. Moreover, the generation of ROS is a fundamental process in higher plants and employs to transmit cellular signaling information in response to the changing environmental conditions. One of the most crucial consequences of abiotic stress is the disturbance of the equilibrium between the generation of ROS and antioxidant defense systems triggering the excessive accumulation of ROS and inducing oxidative stress in plants. Notably, the equilibrium between the detoxification and generation of ROS is maintained by both enzymatic and nonenzymatic antioxidant defense systems under harsh environmental stresses. Although this field of research has attracted massive interest, it largely remains unexplored, and our understanding of ROS signaling remains poorly understood. In this review, we have documented the recent advancement illustrating the harmful effects of ROS, antioxidant defense system involved in ROS detoxification under different abiotic stresses, and molecular cross-talk with other important signal molecules such as reactive nitrogen, sulfur, and carbonyl species. In addition, state-of-the-art molecular approaches of ROS-mediated improvement in plant antioxidant defense during the acclimation process against abiotic stresses have also been discussed.Keywords: abiotic stress; antioxidant systems; ascorbate-glutathione pathway; cross tolerance; H2O2; oxidative stress; plant stress tolerance; reactive nitrogen species; reactive oxygen species; stress signaling
The normal biochemical reactions in our body, increased exposure to the environment, and higher levels of dietary xenobiotic's result in the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The ROS and RNS create oxidative stress in different pathophysiological conditions. The reported chemical evidence suggests that dietary antioxidants help in disease prevention. The antioxidant compounds react in one-electron reactions with free radicals in vivo/in vitro and prevent oxidative damage. Therefore, it is very important to understand the reaction mechanism of antioxidants with the free radicals. This review elaborates the mechanism of action of the natural antioxidant compounds and assays for the evaluation of their antioxidant activities. The reaction mechanisms of the antioxidant assays are briefly discussed (165 references). Practical applications: understanding the reaction mechanisms can help in evaluating the antioxidant activity of various antioxidant compounds as well as in the development of novel antioxidants.
These enzymes also require co-factors such as selenium, iron, copper, zinc, and manganese for optimum catalytic activity. It has been suggested that an inadequate dietary intake of these trace minerals may compromise the effectiveness of these antioxidant defense mechanisms. The consumption and absorption of these important trace minerals may decrease with aging.
Antioxidants, such as vitamins C and E and carotenoids, may help protect cells from damage caused by free radicals. Other naturally occurring antioxidants include flavonoids, tannins, phenols and lignans. Plant-based foods are the best sources. These include fruits, vegetables, whole grains, nuts, seeds, herbs and spices, and even cocoa.
As a bonus, fruits, vegetables and whole grains high in antioxidants are also typically high in fiber, low in saturated fat and cholesterol, and good sources of vitamins and minerals. So enjoy the variety.
Every one of us has both free radicals and antioxidants present inside of our bodies at all times. Some antioxidants are made from the body itself, while we must get others from our diets by eating high-antioxidant foods that double as anti-inflammatory foods.
What is an antioxidant, and why is it important? While there are many ways to describe what antioxidants do inside the body, one antioxidant definition is any substance that inhibits oxidation, especially one used to counteract the deterioration of stored food products or remove potentially damaging oxidizing agents in a living organism.
Antioxidants include dozens of food-based substances you may have heard of before, such as carotenoids like beta-carotene, lycopene and vitamin C. These are several examples of antioxidants that inhibit oxidation, or reactions promoted by oxygen, peroxide and/or free radicals.
Along with other compounds on the list of antioxidants, vitamin C antioxidants are highly effective at neutralizing free radicals to protect against disease. Other vitamins and minerals that have powerful antioxidant properties include vitamin A, vitamin E, manganese and selenium.
As described above, the single most important benefit of antioxidants is counteracting free radicals found inside every human body, which are very destructive to things like tissue and cells. Free radicals are responsible for contributing to many health issues and have connections to such diseases as cancer and premature aging of the skin or eyes.
These antioxidants are believed to be easily transported around the body, especially to the delicate parts of the eyes called the macula and the lens. In fact, there are more than 600 different types of carotenoids found in nature, but only about 20 make their way into the eyes.
Similarly, flavonoid antioxidants found in berries, such as bilberries or grapes (also great sources of the antioxidant resveratrol), may be especially beneficial at supporting vision into older age.Ad 041b061a72