Singlet Oxygen In Tumor Therapy

Our understanding of radiation chemistry has developed over a recent year; compounds have been develop which can modify the initial radiochemical event. There had been extensive investigation on the effect of oxygen in tumor therapy after its recognition by Gary et al in 1953 101. Membranes and DNA are important targets for ionizing radiation and are major sites for the development of the oxygen effects. The involvement of reactive oxygen species such as the superoxide anion and the hydroxyl radical to explain ionizing radiations cytotoxic effects 102. Free radicals are highly reactive molecular species. They react with almost every type of cellular molecules, causing cell injury ,metabolic disturbance, and eventually cell death 103. Oxygen …show more content…
During the exercise singlet oxygen is generated by radiations, the action of lipoxygenases or peroxidases, and by the reaction of hydrogen peroxide with HOCl, superoxide anion, or peroxynitrate, as well as during the respiratory burst of phagocytes . Singlet oxygen is soft and non-toxic for mammalian cells that can be generated during the oxidative stress and has capability to attack cellular molecules like amino acids, nucleic acids and membrane lipids. It is also involved in the oxidation of cholesterol 112, Singlet oxygen is both a signal and a weapon have curative power against various pathogens such as microbes, viruses, and cancer cells in the human organisms.

a.2.2.4) Peroxynitrite (ONOO-) Peroxynitrite radicals may be generated by the action of NO· on superoxide anion as shown below: The peroxynitrite have high diffusibility across the cell membranes and play significant role as a biological oxidant. It is cytotoxic, materialize to be main tissue damaging specie generated at the site of inflammation, tissue injury and oxidizes low-density lipoprotein (LDL) and cause various kidney diseases and neurodegenerative disorders …show more content…
Observation shows that the mitochondrion is particularly susceptibleto oxidative stress .The excess production of reactive oxygen species (ROS) such as superoxide anion (O2¯), singlet oxygen (1O2 ), hydrogen peroxide (H2O2) and the hydroxyl (·OH) radical byorganisms are thought to be involved in damaging of lipid, protein and DNA in mitochondriaand other biological systems. The uses of antioxidants were suggested as anti-aging agents

a.5) Antioxidants
An antioxidant as a substance is effective in the prevention of oxidation by molecular oxygen and therefore, helps to prolong the lifetime. Thus, antioxidants found nearly in all material which is potentially oxidizable. In recent years antioxidants are of major interest for both food scientists and health professionals. The importance of antioxidants to the food industry is in the prevention of rancidity, off- flavor, and similar phenomenon . Hence, the food scientists frequently link antioxidants with "inhibitors of lipid peroxidation and resulting food deterioration". By comparison, in the human body tissues as well as gastrointestinal tract, oxidative damage to proteins and DNA is just as important as damage to lipids . Indeed, oxidative DNA damage is a major factor in the development of cancer, so that dietary antioxidants can prevent the body from damage caused by ROS, and would be expected to have an anticancer effect. Hence, a broader definition of an antioxidant is; that “Any substance that,

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