Study of the different aspects of protection against the exposure of ionizing radiation has always been an active area of research. High cost and toxicity of radioprotective drugs have limited their use. So, search for new drugs with a high degree of protection and lower cost and side effects seem a necessity. In this study radioprotective effect of aqueous as well as alcoholic extracts of the Mann of Cotoneaster nummularia( Shirkhesht), regarding their high accessibility and possibly low side effects, against 2 Gy Gamma irradiation, was analyzed using micronucleus assay on bone marrow cells of male mice (Balb/c). Different doses of 250, 500, 1000 mg/kg/BW for aqueous and 3750, 7500, 15000 mg/kg/BW for alcoholic extract of Shirkhesht were administered IP for five constitutive days prior to 2 Gy gamma irradiation. The result compared with the known radioprotective effect of vitamin E after the same treatment schedule. High frequency of micronucleus was observed in non treated gamma-exposed mice, which represented the clastogenic effect of irradiation. Vitamin E, aqueous and alcoholic extracts of Shirkhesht treated mice represented a 5.56, 3.32 and 2.1 times decrease in the gamma-induced micronucleus frequency respectively. The data suggest a radioprotective effect of shirhkesht compared to vitamin E.

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