Radioprotection of Swiss albino mice by plant extract Mentha piperita (Linn.).

The oral administration of Mentha extract (ME) before exposure to gamma radiation was found to be effective in increasing the frequency of radiation-induced endogenous spleen colonies. A significant increase in the weight of the spleen was observed in animals of the Mentha and radiation combined group in comparison to the irradiation-alone group on day 10 of postirradiation. Furthermore, a significant increase in the body weight of animals in the Mentha and radiation combined group was observed in all the radiation doses studied. A regression analysis of survival data yielded LD50/30 as 6.48 +/- 0.07 and 11.59 +/- 0.21 Gy for the irradiation-alone and the Mentha and radiation combined group, respectively, and produced a dose reduction factor (DRF) of 1.78. Significant increases in total erythrocyte and leucocyte counts, hemoglobin concentration, and hematocrit values were observed in the animals of the Mentha and radiation combined group in comparison to the hematological values observed in the irradiation-alone group at all radiation doses studied (6, 8, and 10 Gy). A dose-dependent decrease in reduced glutathione (GSH) content and an increase in lipid peroxidation (LPO) levels were observed in control animals. However, the animals of the Mentha and radiation combined group exhibited a significant increase in GSH content and a decrease in LPO level, but the values remained below normal. A significant increase in the serum alkaline phosphatase activity was observed in the animals of the Mentha and radiation combined group during the entire period of study, and normal range was evident at 24 h (6 Gy) and day 5 (8 Gy). However, this level could not be restored even at day 30 in 10 Gy exposed animals. Measured acid phosphatase activity in the animals of the Mentha and radiation combined group was found to be significantly lower than the respective controls and attained normal value at day 5 (6 and 8 Gy) and day 20 (10 Gy).