Synthesis, pulse radiolysis, and in vitro radioprotection studies of melatoninolipoamide, a novel conjugate of melatonin and α-lipoic acid

A novel conjugate of melatonin 2 and α-lipoic acid 4 has been prepared using DCC mediated coupling. The conjugate named melatoninolipoamide has been assigned its structure 1 on the basis of spectral analysis (UV, IR, NMR, and EI-MS). Pulse radiolysis studies of the conjugate were carried out in aqueous solutions with both oxidizing and reducing radicals. The results indicate that the melatonin moiety of the conjugate reacts preferably with oxidizing radicals and the lipoic acid moiety exhibits preferential reaction with reducing radicals. The in vitro radioprotection ability of 1 was examined by γ-radiation induced lipid peroxidation in liposomes and hemolysis of erythrocytes, and compared the results with those of melatonin and α-lipoic acid. The studies suggest that the conjugate can be explored as a probable radioprotector.

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