.6,7 Unlike most small-molecule biological antioxidants such as vitamin C (ascorbic acid), α-tocopherol (vitamin E), lipoic acid etc., melatonin does not redox-cycle.
It undergoes molecular rearrangement, effectively removing the free electron from the system – a so-called suicidal antioxidant (Fig. 1).
Each of these products of rearrangement is also a potent antioxidant in its own right.2,8,9 Furthermore, most of these processes involve more than one reactive oxygen species (ROS) per step, so that one melatonin molecule could scavenge up to 10 radical species before the final metabolite is eliminated form the body.
10 Additionally, the relative position of melatonin and its metabolites in the antioxidant “pecking order” (electrochemical potential) may contribute greatly to its utility in biological systems.11