Beam Induced Damage in Human Colon-Derived

Unavoidable exposure to radiosensitive normal tissues around cancerous tumor during 9 the radiotherapy can cause side effects such as self-limited acute toxicities, mild chronic symptoms, 10 or severe organ dysfunction. Nevertheless, clinical use of currently available radiation protective 11 agents is limited because of their generic cytotoxicity. A study on radiation protective effect of 12 delphinidin was conducted with proton-beam-exposed human colon cells (CCD-18Co). The 13 measurement in changes of survival fractions of CCD-18Co with/without delphinidin 14 administration at different radiation doses were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 15 diphenyl tetrazolium bromide (MTT) assay. The changes in expression of reactive oxygen species 16 (ROS) and in activities of antioxidant enzymes were measured by colorimetric assays using 17 pertinent assay kits. The measurement of pro-apoptosis/pro-survival protein expressions using 18 Western blot assay and the measurement of DNA damage using comet assay were also fulfilled to 19 evaluate the molecular level of radiation damages in CCD-18Co cells. The experimental results 20 revealed that the pre-administration of delphinidin regulated antioxidant enzymes, reduced ROS, 21 decreased DNA damage, regulated pro-apoptosis/pro-survival proteins, and eventually reduced 22 apoptosis of CCD-18Co cells. In conclusion, it is claimed that delphinidin is nontoxic natural 23 radiation protective compound, and thus delphinidin can be used to protect normal colon tissues 24 during the proton beam therapy. 25