Synthesis and Radioprotective Effect of Zinc(II) Complexes with Cysteamine, Cysteine and Mercaptopropionylglycine

Complexes of Zn(II) with radioprotective thiol ligands such as cysteamine, L-cysteine and N-(2-mercaptopropionyl)glycine have been synthesized, characterized, and evaluated for cytotoxicity and radioprotective effect. Zn2(N-(2-mercaptopropionyl)glycine)2 when given intraperitoneally at a dose of 14.1 mgkg−1, 30 min before whole-body γ-irradiation (9.0 Gy, 1 Gy min−1), resulted in 68% 30-day survival of CD2F1 mice. This radioprotection was significantly better than that afforded by equimolar doses of ZnCl2 (7%), by N-(2-mercaptopropionyl)glycine (0%), or by a mixture of ZnCl2 and N-(2-mercaptopropionyl)-glycine (0%). Zn(cysteamine)2 and Zn(L-cysteine)2 afforded 14% and 7% survival of CD2F1 mice. These data show that the radioprotective effect of thiols such as N-(2-mercaptopropionyl)glycine can be enhanced by complexation with Zn(II).