The Effects of Antioxidants on Radiation- Induced Chromosomal Damage in Cancer and Normal Cells Under Radiation Therapy Conditions

Radiotherapy is the major form of treatment for many human cancer. During the course of treatment, the ionising radiation produces many biological effects not only in cancer but also in normal cells. Due to the risk of toxicity to normal cells, the radioprotectors are needed to reduce the normal tissue injury during the irradiation of tumours without influence on effectiveness on cancer treatment. Most of the compounds that showed the radioprotective capacity in laboratory studies failed because of their toxicity to the normal cells. The good radioprotector should be non-toxic and should selectively eliminate the cancer cells. A number of natural dietary ingredients show capacity to protect cells from damage induced by ionising radiation (Arora et al., 2008). It is well known that antioxidant vitamins such as ascorbic acid and vitamin E protect cellular DNA and membranes from radiation-induced damage (Noroozi et al., 1998; Konopacka & Rzeszowska-Wolny, 2001; Kumar et al., 2002; Jagetia, 2007). Recently, several flavonoids, polyphenols and phenolic acids have become more popular as diet compounds due to their beneficial impact on human health. One of them is ferulic acid. It renders preferential radioprotection to normal tissue, but not to tumour cells under both ex vivo and in vivo conditions (Maurya et al., 2005; Maurya & Nair, 2006). Ferulic acid is present in many plant products such as giant fennel, green tea, coffee beans and grains. It is monophenolic phenylpropanoid that acts as an antioxidant against peroxyl radicals-induced oxidation in neuronal culture and in synaptosomal membranes (Kanski et al., 2002). It was found that ferulic acid reduced the number of radiation-induced DNA strand breaks and enhanced the DNA repair processes in peripheral blood lymphocytes but not influenced the level of radiation-induced damage in fibroblastoma tumour cells in mice (Maurya et al., 2005). It has been also showed that the α-tocopherole can preferentially reduce the level of radiation-induced chromosomal damage in normal human cells, but in cancer cells it