Oxygen is a double-edged sword. We cannot live without oxygen but at same time we are continuously exposed to oxygen toxicity. However molecular oxygen is neither very reactive nor very toxic. The apparent toxicity of oxygen is actually due to free oxygen radicals formed by partial reduction of molecular oxygen. Moreover, a free radical of any species is capable of independent existence hence term free. Generally enhanced reactivity of free radicals over more stable molecules result from the fact that more energy is required, for example, to maintain two separate species with an unpaired electron than to allow them to...
are vitamin E, -carotene and vitamin C. A potent radioprotector neutralizes free radicals and mitigates oxidative stress and may also stimulate inherent oxidant defence system. Modification of radiation response can be achieved by means of chemical substances that can significantly decrease the magnitude of the response when present in a biologic system during irradiation. This type of modification may be classified as chemical protection and substances responsible for it may be termed chemical protectors or chemical radioprotectors. In recent years there has been a growing interest in the research concerned to the modification of radiation injury in biological systems.