Figure 2.

The targeting of melatonin to the mitochondria. Melatonin enters the organelles through specific oligopeptide transporters (PETP 1/2). In these organelles melatonin reduces ROS and prevent lipid peroxidation. Melatonin in mitochondria increase the efficiency of the electron transport chain and improve ATP production. ROS produced by this reaction are directly scavenged by melatonin but are also scavenged by mitochondria SIRT3 and metabolized by SOD2. Melatonin also modulates UCP2 for maintaining the inner mitochondrial membrane potential and prevents opening of the MPT pore. This limit the translocation of cytochrome c in cell cytosol and, so, prevents cellular apoptosis.