**7. Conclusion**

Given the central role of DNA as radiobiological target, the design of radioprotectors which bind to DNA is an obvious strategy, however neither of the DNA binding radioprotectors discussed in this paper arose from such a deliberate design plan. WR1065 and amifostine emerged from an empirical drug development program, and the association between radioprotective efficacy and DNA binding only became evident in retrospect. In the case of methylproamine, derived from a minor groove DNA binding ligand developed for an entirely different purpose, and found to have a serendipitous radioprotective activity, incorporation electron-rich substituents has improved radioprotective activity compared to Hoechst 33342. No doubt this rational thread might be followed more explicitly in the design of future radioprotectors, but it remains to be seen whether it is possible to design DNA-binding radioprotectors that are devoid of any toxicity derived from the DNA-binding property.
