Free-radical scavenging activity of radioprotectors: comparison between clinically used radioprotectors and natural antioxidants

Clinically used radioprotectors, amifostine and cysteamine, have been shown to possess free-radical scavenging activities. Natural antioxidants also possess free-radical scavenging activities, some of which have been shown to have radioprotective capability. We carried out a quantitative determination of the scavenging abilities in amifostine and cysteamine and compared the potencies with natural antioxidants by using multiple free-radical scavenging method. Overall, amifostine and cysteamine showed scavenging activity as potent as natural antioxidants. We found a correlation between scavenging activity and radioprotective efficiency that was previously determined in rat thymocytes. These correlations are indicative that natural antioxidants can be effective radioprotectors.