Radioprotective Effect of Pyridoxamine-5-thiophosphate and Related Compounds

抄録

Among 6 derivatives of 5-mercaptopyridoxine, pyridoxamine-5-thiophosphate was most powerful in protecting mice from X-radiation. Its efficacy was nearly comparable with that of the typical radioprotector, cysteamine. It was less toxic than any other derivatives tested, the ratio of the median lethal dose to the minimum radioprotective dose was smaller than 1/4. It was effective when administered orally as well as when injected intraperitoneally. Quicker recovery of leucocyte number was observed in the circulating blood of the protected animals than in the controls. The compound protected an enzyme protein (β-glucuronidase) from radiation-inactivation in aqueous solution as powerfully as cysteamine did. However, it was much less effective than cysteamine in protecting HeLa S₃ cells from the loss of reproductive integrity caused by radiation.