Antioxidants

Mitochondria play a central role in the cell physiology. Besides their classic function of energy metabolism, mitochondria are involved in multiple cell functions including energy distribution through the cell, energy/heat modulation, regulation of reactive oxygen species (ROS), calcium homeostasis and apoptosis control. Simultaneously mitochondria are the main producer and target of ROS and with the result, multiple mitochondrial diseases are related to ROS induced mitochondrial injuries. Increased free radical generation, enhanced mitochondrial inducible nitric oxide (NO) synthase activity, enhanced NO production, decreased respiratory complex activity, impaired electron transport system, and opening of mitochondrial permeability transition pore all have been suggested as factors responsible for impaired mitochondrial function. Among these, neurodegenerative diseases such as Alzheimer´s disease (AD), Parkinson´s disease (PD), amyotrophic lateral sclerosis (ALS), Huntington´s disease (HD) and aging are caused by ROS-induced mitochondrial dysfunctions. Melatonin, the major hormone of the pineal gland, also acts as an antioxidant and as a regulator of mitochondrial bioenergeticfunction. Melatonin is selectively taken up by mitochondrial membranes, a function not shared by other antioxidants, and thus has emerged as a major potential therapeutic tool for treating neurodegenerative disorders. Multiple in vitro and in vivo experiments have shown the protective role of melatonin for preventing oxidative stress induced mitochondrial dysfunction seen in experimental models of PD, AD, and HD. Keeping these functions into consideration, this article was framed to review the protective role of melatonin with mechanistic insights against mitochondrial diseases, and may suggest the new avenues for safe and effective treatment modalities against these devastating neurodegenerative diseases. Future insights have also been discussed.