In order to understand how antioxidants work, we must start at the When the free radicals (pro-oxidants) outnumber the antioxidants, this can. Understanding Oxidants and Diabetes Complications. April 4, Dr. Keith Blackwell. Dr. Robert Stanton. You may have heard about the importance of. They can either donate an electron to or accept an electron from other molecules, therefore behaving as oxidants or reductants. The most important.
Researchers have also noted that free radical damage accumulates with age. Because it is not possible to directly measure free radicals in the body, scientists have reached these conclusions by measuring the by-products that result from free radical reactions.
So where do anti-oxidants come in? Anti-oxidants fight free radicals. Our bodies naturally contain certain anti-oxidant enzymes such as superoxide dismutase, but we can also get them from the foods we eat. The best known anti-oxidants are beta carotene, vitamins C and E, and the mineral selenium.
Other anti-oxidants include ginkgo biloba, coenzyme Q10, tocotrienols, and polyphenols, which are substances found in most plants. It is important to note, however, that all anti-oxidants do not do the same job or work in the same manner. For example, copper, manganese, zinc, selenium and other trace minerals are really only anti-oxidants when they combine with bodily enzymes to try to eliminate free radicals.
Vitamins A, C, E and beta-carotene seem to work on their own or in conjunction with each other. Vitamin C, for instance can work in partnership with vitamin E, cleaning free radical substances from vitamin E molecules so those molecules can continue to attack other free radicals.
Beta-carotene converts to vitamin A, a powerful anti-oxidant, when there is a shortage of vitamin A in the body. Lycopene, found in many fruits and vegetables, appears to assist the male prostate, although it also has a positive anti-oxidant effect body wide as well. As you can see, all anti-oxidants are not created equal. There is also such a thing as too much of an anti-oxidant; Vitamin A can be toxic when taken in too large a quantity. Catalase is a common enzyme found in nearly all living organisms, which are exposed to oxygen, where it functions to catalyze the decomposition of hydrogen peroxide to water and oxygen.
To this end, catalase is frequently used by cells to rapidly catalyze the decomposition of hydrogen peroxide into less reactive gaseous oxygen and water molecules. The glutathione system includes glutathione, glutathione reductase, glutathione peroxidases, and glutathione S-transferases. This system is found in animals, plants, and microorganisms. There are at least four different glutathione peroxidase isozymes in animals. The glutathione S-transferases show high activity with lipid peroxides.
These enzymes are at particularly high levels in the liver and also serve in detoxification metabolism. As it cannot be synthesized in humans and must be obtained from the diet, it is a vitamin. In cells, it is maintained in its reduced form by reaction with glutathione, which can be catalyzed by protein disulfide isomerase and glutaredoxins. Glutathione is a cysteine-containing peptide found in mostforms of aerobic life. Glutathione has antioxidant properties since the thiol group in its cysteine moiety is a reducing agent and can be reversibly oxidized and reduced.
In cells, glutathione is maintained in the reduced form by the enzyme glutathione reductase and in turn reduces other metabolites and enzyme systems as well as reacting directly with oxidants. Melatonin, also known chemically as N-acetylmethoxytryptamine,[ 65 ] is a naturally occurring hormone found in animals and in some other living organisms, including algae.
Melatonin, once oxidized, cannot be reduced to its former state because it forms several stable end-products upon reacting with free radicals. Therefore, it has been referred to as a terminal or suicidal antioxidant.
Vitamin E is the collective name for a set of eight related tocopherols and tocotrienols, which are fat-soluble vitamins with antioxidant properties.
Uric acid accounts for roughly half the antioxidant ability of plasma. In fact, uric acid may have substituted for ascorbate in human evolution. Synthetic and natural food antioxidants are used routinely in foods and medicine especially those containing oils and fats to protect the food against oxidation.
There are a number of synthetic phenolic antioxidants, butylated hydroxytoluene BHT and butylated hydroxyanisole BHA being prominent examples. These compounds have been widely uses as antioxidants in food industry, cosmetics, and therapeutic industry. However, some physical properties of BHT and BHA such as their high volatility and instability at elevated temperature, strict legislation on the use of synthetic food additives, carcinogenic nature of some synthetic antioxidants, and consumer preferences have shifted the attention of manufacturers from synthetic to natural antioxidants.
It has been reported that there is an inverse relationship between the dietary intake of antioxidant-rich food and medicinal plants and incidence of human diseases. The use of natural antioxidants in food, cosmetic, and therapeutic industry would be promising alternative for synthetic antioxidants in respect of low cost, highly compatible with dietary intake and no harmful effects inside the human body.
Many antioxidant compounds, naturally occurring in plant sources have been identified as free radical or active oxygen scavengers. In the last decade, preventive medicine has undergone a great advance, especially in developed countries. Research has demonstrated that nutrition plays a crucial role in the prevention of chronic diseases, as most of them can be related to diet. Functional food enters the concept of considering food not only necessary for living but also as a source of mental and physical well-being, contributing to the prevention and reduction of risk factors for several diseases or enhancing certain physiological functions.
Broccoli, carrots, and tomatoes are considered functional foods because of their high contents of physiologically active components sulforaphen, B-carotene, and lycopene, respectively. Green vegetables and spices like mustard and turmeric, used extensively in Indian cuisine, also can fall under this category.
A nutraceutical is any nontoxic food extract supplement that has scientifically proven health benefits for both the treatment and prevention of disease. The major active nutraceutical ingredients in plants are flavonoids. As is typical for phenolic compounds, they can act as potent antioxidants and metal chelators. They also have long been recognized to possess anti-inflammatory, antiallergic, hepatoprotective, antithrombotic, antiviral, and anticarcinogenic activities.
Ingredients that make food functional are dietary fibers, vitamins, minerals, antioxidants, oligosaccharides, essential fatty acids omega-3 , lactic acid bacteria cultures, and lignins. Many of these are present in medicinal plants. Indian systems of medicine believe that complex diseases can be treated with complex combination of botanicals unlike in west, with single drugs. Whole foods are hence used in India as functional foods rather than supplements. Some medicinal plants and dietary constituents having functional attributes are spices such as onion, garlic, mustard, red chilies, turmeric, clove, cinnamon, saffron, curry leaf, fenugreek, and ginger.
Some herbs as Bixa orellana and vegetables like amla, wheat grass, soyabean, and Gracinia cambogia have antitumor effects. Other medicinal plants with functional properties include A. Free radicals damage contributes to the etiology of many chronic health problems such as cardiovascular and inflammatory disease, cataract, and cancer.
Antioxidants prevent free radical induced tissue damage by preventing the formation of radicals, scavenging them, or by promoting their decomposition. Synthetic antioxidants are recently reported to be dangerous to human health.
Thus the search for effective, nontoxic natural compounds with antioxidative activity has been intensified in recent years. In addition to endogenous antioxidant defense systems, consumption of dietary and plant-derived antioxidants appears to be a suitable alternative. Dietary and other components of plants form a major source of antioxidants. The traditional Indian diet, spices, and medicinal plants are rich sources of natural antioxidants; higher intake of foods with functional attributes including high level of antioxidants in antioxidants in functional foods is one strategy that is gaining importance.
Newer approaches utilizing collaborative research and modern technology in combination with established traditional health principles will yield dividends in near future in improving health, especially among people who do not have access to the use of costlier western systems of medicine.
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This article has been cited by other articles in PMC. Abstract In recent years, there has been a great deal of attention toward the field of free radical chemistry.
Ageing, antioxidant, free radicals, oxidative stress. Production of free radicals in the human body Free radicals and other ROS are derived either from normal essential metabolic processes in the human body or from external sources such as exposure to X-rays, ozone, cigarette smoking, air pollutants, and industrial chemicals.
Some internally generated sources of free radicals are[ 8 ] Mitochondria. Free radicals in biology Free radical reactions are expected to produce progressive adverse changes that accumulate with age throughout the body [ Table 1 ].
Open in a separate window. Cardiovascular diseases Heart diseases continue to be the biggest killer, responsible for about half of all the deaths. Carcinogenesis Reactive oxygen and nitrogen species, such as super oxide anion, hydrogen peroxide, hydroxyl radical, and nitric oxide and their biological metabolites also play an important role in carcinogenesis.
Free radical and aging The human body is in constant battle to keep from aging. Oxidative damage to protein and DNA Oxidative damage to protein Proteins can be oxidatively modified in three ways: Lipid peroxidation Oxidative stress and oxidative modification of biomolecules are involved in a number of physiological and pathophysiological processes such as aging, artheroscleosis, inflammation and carcinogenesis, and drug toxicity. History The term antioxidant originally was used to refer specifically to a chemical that prevented the consumption of oxygen.
Antioxidant defense system Antioxidants act as radical scavenger, hydrogen donor, electron donor, peroxide decomposer, singlet oxygen quencher, enzyme inhibitor, synergist, and metal-chelating agents. Mechanism of action of antioxidants Two principle mechanisms of action have been proposed for antioxidants. Levels of antioxidant action The antioxidants acting in the defense systems act at different levels such as preventive, radical scavenging, repair and de novo, and the fourth line of defense, i.
Catalase Catalase is a common enzyme found in nearly all living organisms, which are exposed to oxygen, where it functions to catalyze the decomposition of hydrogen peroxide to water and oxygen. Glutathione systems The glutathione system includes glutathione, glutathione reductase, glutathione peroxidases, and glutathione S-transferases. Glutathione Glutathione is a cysteine-containing peptide found in mostforms of aerobic life.
Melatonin Melatonin, also known chemically as N-acetylmethoxytryptamine,[ 65 ] is a naturally occurring hormone found in animals and in some other living organisms, including algae. Tocopherols and tocotrienols Vitamin E Vitamin E is the collective name for a set of eight related tocopherols and tocotrienols, which are fat-soluble vitamins with antioxidant properties. Uric acid Uric acid accounts for roughly half the antioxidant ability of plasma.
Indian dietary and medicinal plants as functional foods Ingredients that make food functional are dietary fibers, vitamins, minerals, antioxidants, oligosaccharides, essential fatty acids omega-3 , lactic acid bacteria cultures, and lignins. Footnotes Source of Support: Nil Conflict of Interest: Methodological consideration for characterization for potential antioxidant actions of bioactive components in plants foods. Pathological roles of reactive oxygen species and their defence mechanism.
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Understanding Oxidants and Diabetes Complications
Oxidants, antioxidants and the current incurability of metastatic cancers Also key to better understanding is why and how the anti-diabetic drug metformin (the . Oxidant species such as superoxide radical (O), hydrogen peroxide in our understanding of the primary mechanism of oxidant toxicity to cells, and in. Anti-oxidants have recently become a buzzword in nutrition and cancer To understand how, it is important to first examine another set of.