Oxidative Stress And Human Diseases: The role of oxidative stress has been postulated in many conditions, including atherosclerosis, inflammatory condition, certain cancers, and the process of aging. Oxidative stress is now thought to make a significant contribution to all inflammatory diseases (arthritis, vasculitis, glomerulonephritis, lupus erythematous, adult respiratory diseases syndrome), ischemic diseases (heart diseases, stroke, intestinal ischemia), hemochromatosis, acquired immunodeficiency syndrome, emphysema, organ transplantation, gastric ulcers, hypertension and preeclampsia, a neurological disorder (Alzheimer’s disease, Parkinson’s disease, muscular dystrophy), alcoholism, smoking-related diseases, and many others. An excess of oxidative stress can lead to the oxidation of lipids and proteins, which is associated with changes in their structure and functions.
Heart diseases continue to be the biggest killer, responsible for about half of all the deaths. The oxidative events may affect cardiovascular diseases therefore, it has the potential to provide enormous benefits to the health and lifespan. Polyunsaturated fatty acids occur as a major part of the low-density lipoproteins (LDL) in blood and oxidation of these lipid components in LDL play a vital role in atherosclerosis. The three most important cell types in the vessel wall are endothelial cells; smooth muscle cells and macrophages can release free radicals, which affect lipid peroxidation, and with a continued high level of oxidized lipids, blood vessel damage to the reaction process continues and can lead to the generation of foam cells and plaque the symptoms of atherosclerosis. Oxidized LDL is atherogenic and is thought to be important in the formation of atherosclerosis plaques Furthermore, oxidized LDL is cytotoxic and can directly damage endothelial cells. Antioxidants like B-carotene or vitamin E play a vital role in the prevention of various cardiovascular diseases.
Reactive oxygen and nitrogen species, such as superoxide anion, hydrogen peroxide, hydroxyl radical, and nitric oxide and their biological metabolites also play an important role in carcinogenesis. ROS induce DNA damage, as the reaction of free radicals with DNA includes strand break base modification and DNA protein cross-links. Numerous investigators have proposed the participation of free radicals in carcinogenesis, mutation, and transformation; their presence in the biosystem could lead to mutation, transformation, and ultimately cancer. Induction of mutagenesis, the best known biological effect of radiation, occurs mainly through damage of DNA by the HO. Radical and other species are produced by the radiolysis, and also by direct radiation effect on DNA, the reaction effects on DNA. The reaction of HO. Radicals are mainly in addition to the double bond of pyrimidine bases and abstraction of hydrogen from the sugar moiety resulting in a chain reaction of DNA. These effects cause cell mutagenesis and carcinogenesis. lipid peroxides are also responsible for the activation of carcinogens.
Antioxidants can decrease oxidative stress-induced carcinogenesis by direct scavenging of ROS and/or by inhibiting cell proliferation secondary to protein phosphorylation. B-carotene may be protective against cancer through its antioxidant function because oxidative products can cause genetic damage. Thus, the photoprotective properties of B-carotene may protect against ultraviolet light-induced carcinogenesis. Immunoenhancement of B-carotene may contribute to cancer protection. B-carotene may also have an anticarcinogenic effect altering the liver metabolism effects of carcinogens. Vitamin C may help prevent cancer. The possible. mechanisms by which vitamin C may affect carcinogenesis include antioxidant effects, blocking of formation of nitrosamines, enhancement of the immune response, and acceleration of detoxification of liver enzymes. Vitamin E, an important antioxidant, plays a role in immunocompetence by increasing humoral antibody protection, resistance to bacterial infections, cell-mediated immunity, the T-lymphocytes tumor necrosis factor production, inhibition of mutagen formation, repair of membranes in DNA, and blocking micro cell line formation. Hence vitamin E may be useful in cancer prevention and inhibit carcinogenesis by the stimulation of the immune system. The administration of a mixture of the above three antioxidants revealed the highest reduction in risk of developing cardiac cancer.
Free Radical And Aging
The human body is in a constant battle to keep from aging. Research suggests that free radical damage to cells leads to the pathological changes associated with aging. An increasing number of diseases or disorders, as well as the aging process itself, demonstrate link either directly or indirectly to these reactive and potentially destructive molecules. The major mechanism of aging attributes to DNA or the accumulation of cellular and functional damage. Reduction of free radicals or decreasing their rate of production may delay aging. Some of the nutritional antioxidants will retard the aging process and prevent disease. Based on these studies, it appears that increased oxidative stress commonly occurs during the aging process, and antioxidant status may significantly influence the effects of oxidative damage associated with advancing age. Research suggests that free radicals have a significant influence on aging, that free radical damage can be controlled with adequate antioxidant defense, and that optimal intake of an antioxidant nutrient may contribute to enhanced quality of life. Recent research indicates that antioxidants may even positively influence the life span.
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