Antioxidants
<p><b>An antioxidant</b> is a molecule that inhibits the oxidation of other molecules. Oxidation is a chemical reaction that can produce free radicals, leading to chain reactions that may damage cells. Antioxidants such as thiols or ascorbic acid (vitamin C) terminate these chain reactions. The term "antioxidant" is mainly used for two different groups of substances: industrial chemicals which are added to products to prevent oxidation, and natural chemicals found in foods and body tissue which are said to have beneficial health effects.</p>
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To balance the oxidative state, plants and animals maintain complex systems of overlapping antioxidants, such as glutathione and enzymes (e.g., catalase and superoxide dismutase) produced internally or the dietary antioxidants: vitamin A, vitamin C, and vitamin E.</p>
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Antioxidant dietary supplements do not improve health nor are they effective in preventing diseases as shown by randomized clinical trials including supplements of beta-carotene, vitamin A, and vitamin E singly or in different combinations having no effect on mortality rate or cancer risk. Supplementation with selenium or vitamin E does not reduce the risk of cardiovascular disease.[5][6] Oxidative stress can be considered as either a cause or consequence of some diseases, an area of research stimulating drug development for antioxidant compounds for use as potential therapies.</p>
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<b>Antioxidants</b> can attenuate the damaging effects of ROS in vitro and delay many events that contribute to cellular aging. The use of multivitamin/mineral supplements (MVMs) has grown rapidly over the past decades. Some recent studies demonstrated no effect of antioxidant therapy; sometimes the intake of antioxidants even increased mortality. Oxidative stress is damaging and beneficial for the organism, as some ROS are signaling molecules in cellular signaling pathways. Lowering the levels of oxidative stress by antioxidant supplements is not beneficial in such cases. The balance between ROS and antioxidants is optimal, as both extremes, oxidative and antioxidative stress, are damaging. Therefore, there is a need for accurate determination of individual's oxidative stress levels before prescribing the supplement antioxidants.</p>
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Molecular oxygen was introduced to the early reducing atmosphere of the Earth about 2.7 billion years ago by O2- evolving photosynthetic organisms, causing the advent of the reactive oxygen species (ROS) as unwanted byproducts (Halliwell, 2006). Aerobic metabolism constantly generates ROS which are confined to the different plant cellular compartments, like the chloroplast, mitochondria and peroxisomes. Recent findings also shed light on the role of apoplast as a site for ROS generation (Jubany-Marí et al., 2009; Roychoudhury and Basu, 2012). Under favorable conditions, ROS is constantly being generated at basal levels. However, they are unable to cause damage, as they are being scavenged by different antioxidant mechanisms (Foyer and Noctor, 2005). The delicate balance between ROS generation and ROS scavenging is disturbed by the different types of stress factors like salinity, drought, extreme temperatures, heavy metals, pollution, high irradiance, pathogen infection, etc</p>
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<img src="/8fa0c73e-245f-54f9-87a4-b47ce89da029.png"/> There are three primary types of antioxidants found in nature. These include phytochemicals, vitamins, and enzymes. Most of the most powerful antioxidants are found in plants. This is due to the fact that plants are exposed to UV light all throughout the day. <br />
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Because plants generate a large number of free radicals, they have a natural built-in protection system that prevents the free radicals from causing the cellular damage that would eventually result in the plant withering and dying. This protection comes from naturally-occurring antioxidants.</p>
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Example enzymes are synthesized in the human body, and include superoxide dismutase (SOD), glutathione peroxidase, glutathione reductase, and catalases. In order for antioxidant enzymes to provide optimum antioxidant activity, they require co-factors such as iron, copper, selenium, magnesium, and zinc.</p>
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