Role of melatonin as a protective antioxidant in the amelioration of oxidative stress mediated tissue injury: a new vision for futuristic medicine

Abstract

Melatonin (N-acetyl-5-methoxy tryptamine) is ubiquitous in almost every creature; diatoms, bacteria, plants, and animals. During the
course of organic evolution, melatonin (a pineal secretory product in vertebrates and mammals, including humans) never changed its
structure and thus remain conserved as an ancient molecule in nature. Since discovery of the antioxidant properties of melatonin by
Dr. Dun-Xian Tan in 1993, its antioxidative efficacy in various situations of oxidative stress in plants, animals and humans has been well
established. It is clear that melatonin has evolved much earlier than other antioxidants. Ischaemic heart disease (IHD) and consequential myocardial infarction (MI) is a health problem of global concern and its ubiquitous prevalence is increasing worldwide annually. The involvement of oxidative stress in myocardial ischemia has long been recognized around the globe. Moreover, the prescribed medicines for cardiac tissue well-being sometimes became detrimental for gastric epithelium. Though endogenous gastric melatonin plays a protective role in offering protection to the entire gastric system, stress-mediated challenged melatonin level brings about threats to the gastric system. Mitigation of oxidative stress in the myocardium and gastric system as well, by antioxidants, may play an effective role in protection and the results of our studies carried out through several years have revealed that melatonin offers extensive protection toward the said systems when subjected to stress by physiological as well as synthetic molecules. Further, we have extrapolated our studies to check whether its protective action is extended toward erythrocytes, the first exposed cellular system to various exogenous and endogenous stressors. Moreover, melatonin was also found to exhibit cardio-protection when ISO aggravated high-fat diet-induced oxidative stress-mediated myocardial onslaught. Our studies revealed the association of a unique pathway in cardio-protection by melatonin. These findings further strengthen the role of melatonin as a cardio-protective antioxidant with no or minimal side effects, recognized globally and having immense future therapeutic relevance