Protection of DNA from Radiation by the Medicinal Plant Holarrhena antidysentrica

Objective: To investigate the radioprotecting ability of the extract of the medicinal plant Holarrhena antidysentrica, especially to protect DNA from gammaradiation induced damages. Materials and Methods: Hydo-alcoholic extract of dried roots of Holarrhena antidysentrica (HAE) was prepared, freeze dried and stored at 4C. The DNA of the plasmid pBR322 was exposed to gamma-radiation in presence and absence of HAE and subjected to agarose gel electrophoresis to study radioprotecting ability of the extract under in vitro conditions. The radioprotecting ability of the extract under ex-vivo conditions was examined by performing alkaline comet assay on human peripheral blood leucocytes exposed to the radiation with and without HAE. Mice were whole body exposed to gammaradiation and single cell suspensions of spleen and bone marrow were subjected to alkaline comet assay to investigate the radioprotecting ability of HAE under in vivo conditions. The effect of HAE on radiation induced mortality was checked by monitoring the mortality of mice exposed to 10 Gray(Gy) whole body gamma-radiation after administering HAE. Results: Exposure to gamma-radiation led to induction of DNA strand breaks, resulting in the relaxation of plasmid DNA from super coiled (ccc) form to open circle (oc) form and the presence of HAE during radiation exposure protected the DNA from the induction of strand breaks. The exposure of the human leucocytes to the radiation ex vivo resulted in the increase in the damage to cellular DNA measured as increase in the comet parameters such as percent DNA in tail, tail length and tail moment and olive tail moment and the presence of the extract during irradiation decreased all the comet parameters indicating ex vivo radioprotection of DNA. In whole body irradiated mice cellular DNA damage in bone marrow and spleen cells, seen as increased comet parameters were found reduced by administration of HAE prior to radiation exposure, indicating in vivo radioprotection of DNA. Investigations on survival of animals following acute lethal dose of 10 Gy whole body gammaradiation Address for