Melatonin and redox homeostasis

Abstract

Redox homeostasis and redox signaling are constituents of preservation of a normal physiological state. Whereas the equilibrium between oxidants and nucleophiles is conserved in redox homeostasis, oxidative stress promotes the formation of a radically altered redox state. It is known that modification of circadian clock may lead to severe alteration in redox balance. Melatonin [N-acetyl-5-methoxytryptamine, (MLT)] regulates numerous physiological functions including circadian rhythm, sleep-wake cycle, gonadal activity, redox homeostasis, neuroprotection, immune-modulation, and anticancer activity in organisms. Insufficient MLT production is closely related to development of aging process, tumorigenesis, visceral adiposity, neurodegenerative disorders, etc. Reactive oxygen species (ROS) are not intrinsically harmful or beneficial in cellular redox metabolism. Redox homeostasis is an integrative status for both of the hormetic response to ROS overproduction and subsequent redox signaling. MLT and its derivatives are traditionally classified as hormone-like substances. Their redox sensitive regulatory activity and direct interaction with intracellular ROS serve as second messenger in cell signaling. This review involves the role of redox homeostasis in the pathogenesis of age-related disorders and its relationship with MLT, therefore, targeting the circadian rhythm may propose new therapeutic approach for these disorders.