Pharmacological Studies on Chemical Protectors against Radiation. IV. : Studies on Radioprotective Effects of Vitamin E and its Derivatives

This experiment was undertaken to determine the radioprotective activity of vitamin E and its esterified derivatives, using survival time and body weight changes in X-irradiated mice as the pharmacological indices. Male mice of ddY strain, 5 to 6 weeks old, were used in this experiment. Each group consisting of 10 mice was exposed to 700 R whole body X-irradiation, which caused 100% mortality of the mice without medication within 2 weeks after X-irradiation under the condition adopted for this experiment. The test preparations such as vitamin E, and its acetate, ferulate, caffeate, and succinate were dissolved in sesame oil or cottonseed oil, or suspended in 5% Tween 80 aqueous solution, and administered intraperitoneally 24 or 3 hr. before the irradiation or 5 min after irradiation ; 1 mmole/kg of vitamin E, acetate or ferulate, 0.5 mmole/kg of the caffeate, or 0.25 mmole/kg of the succinate. The potency of radioprotective effect of each preparation was evaluated, based on the elongation of survival time up to 30 days and increase in body weight two weeks after irradiation, comparing with the control. Tween 80, used as the detergent to emulsify the preparation, did not show any influence on survival time and body weight. Sesame oil was slightly radioprotective on survival time and body weight. Cottonseed oil caused decrease in body weight under a certain circumstance. Under the condition of this experiment, vitamin E was little effective, while the acetate was slightly effective, and the other esters were significantly effective, and it was found that radioprotective effect was increased by esterification of vitamin E. It was also found that estimates of the effect based on survival time and on body weight were agreement. Radioprotective effect of the preparations seemed to depend the solvent used and the time of administration.