 2: 249260 (2009) Sharma   249 APPRAISIG RADIOPROTECTIVE POTETIAL OF TIOSPORA CORDIFOLIA (AMRITA) EXTRACT I SWISS ALBIO MICE EXPOSED TO DIFFERET DOSES OF GAMMA RADIATIO Riddhi Sharma, M.Sc, Priyanka Sharma, M.Sc and P.K. Goyal, Ph.D.* Summary The root extract of   (TCE) is a unique drug used in Indian systems of medicine for several diseases and as a vitalizer. Looking at its sundry applications, hydro alcoholic extract was examined for its radio protective potential against gamma radiation in Swiss albino mice. Animals were divided into two groups and irradiated, with or without TCE extracts, given orally at 25, 50, 100, 125, 250, 500, 750, 1000 and 2000 mg.kg.b.wt./day before irradiation. The acute toxicity studies showed that the drug was non5toxic up to a dose of 2500 mg.kg.b.wt./day. Administration of TCE resulted in a dose5dependent decline in radiation induced mortality up to a dose of 75 mg.kg.b.wt./day the dose at which the highest number of survivors (87%) was observed. This was considered optimum dose for radioprotection and used in further radiomodulatory studies exposure to 6, 7, 8, 9, 10 and 11Gy of gamma radiation. The treatment of mice with 75 mg.kg.b.wt./day TCE reduced the severity of symptoms of radiation sickness and mortality at all exposure doses, and a significant increase in survival was observed as compared with the non5 treated irradiated group. The TCE treatment effectively protected mice against the gastrointestinal as well as bone marrow related death, as revealed by the increased number of survivors at all irradiation doses. The dose reduction factor was found to be 1.68. To understand the mechanism of action, biochemical parameters as lipid peroxidation (LPx) & Glutathione (GSH) content were evaluated, indicating radioprotection afforded by TCE may be in part due to the scavenging of reactive oxygen species induced by ionizing radiation.Irradiation of animals resulted in an elevation in lipid peroxidation (LPx) and a significant decline in glutathione in liver. Conversely, administration of animals with TCE before irradiation caused a significant decline in LPx accompanied by a significant incresse in GSH concentration. : Gamma radiation,  , LPx, GSH, Swiss albino mice. *Corresponding author Dr. P. K. Goyal Radiation and Cancer Biology Laboratory, Department of Zoology, University of Rajasthan, Jaipur 302 004 India. Phone 5 09829134133 Fax – 0091 1415 2656273 Email5 pkgoyal2002@rediffmail.com,sonasiddha@gmail.com.