Ionising radiation therapy is a common treatment for different types of cancers. The side effects associated with radiation includes destruction of normal cells, especially the dividing cells. The cells in the gastrointestinal (GI) tract and bone marrow are the primary targets. The GI damage is reflected by early histological changes, functional alterations and symptoms of nausea, vomiting and diarrhea. This has been designated as the radiation syndrome. Many synthetic drugs have been used to treat GI disorders but a definite cure has not been discovered so far and these available medications also cause several side effects. The herbal extracts are being tested for long time as preventive food supplement/drug in this disease. The radio protective effects of Nigella sativa (black cumin, (Ranunculacea) is already reported but its mechanism of action is not well established. Here in this review this aspect has been explored with special reference to various in vitro and in vivo models.Keyword: Nigella sativa; Thymoquinone; Radioprotector; Herbal; Radiation Defence Life Science Journal, Vol. 2, No. 3, July 2017, pp. 264-269, DOI : 10.14429
REVIEW PAPER265 PANDAY, et al.: DEf. LIfE SCI. J., VOL. 2, NO. 3, JuLY 2017, DOI : 10.14429/dlsj.2.11665 cancers of the skin, cervix, prostate, lungs, thyroid and brain), and may be the only treatment needed to cure the cancer 7 . Nevertheless, radiation therapy remains dose limited by the tolerance of surrounding normal tissues.The gastrointestinal tract (GIT) not only is a major doselimiting organ during abdominal, pelvic, and retroperitoneal radiation therapy 8 but is also one of organs for the outcome of accidental whole-body radiation exposure. An exposure to the dose of 5 Gy -8 Gy, may result to death within few weeks. However low dose in the range of 2 Gy -5 Gy, may result to delayed symptoms especially to the hematopoietic system, resulting immunosuppression and rapid manifestation of infections. The GI damage is another cause of death depending on the dose and severity of damage, including intestinal crypt cell death. Therefore, interventions that reduce gastrointestinal radiation injury are urgently needed. Radiation enteritis is a challenging clinical problem in patients receiving ionising radiation 9 . Clinically, irradiation can result in several deleterious gastro-intestinal symptoms such as bleeding, anorexia, nausea, vomiting and diarrhea i.e. gastrointestinal radiation syndrome 10,11 . The high sensitivity of the GIT to ionising radiation (and other cytotoxic insults) is a dose limiting issue in some radio-and chemotherapy practices. The duodenum is the most radiosensitive region of the digestive tract, followed by jejunum, ileum, esophagus, stomach, colon, and rectum, in order of radiosensetivity 12,13 .The mucosal cells are characterised by rapid proliferation rate and relatively high degree of radiosensetivity. In both animal models and patients, small intestinal and whole gut transit was markedly accelerated within hours after irradiation 14,15 . ...