Melatonin: an ancient note in a contemporary wrap

At the beginning of life, natural selection is and still the principal driving force for the evolution of all organisms to adapt in the particular environments of the earth. As a result, ultimately neither the strongest, nor the supreme intelligent but the most adaptable species win the race. Not only the organisms, but also the elements which are necessary for survival of them also undergo extreme evolution. These include DNA, proteins and other biochemical moleculesAt the beginning of life, natural selection is and still the principal driving force for the evolution of all organisms to adapt in the particular environments of the earth. As a result, ultimately neither the strongest, nor the supreme intelligent but the most adaptable species win the race. Not only the organisms, but also the elements which are necessary for survival of them also undergo extreme evolution. These include DNA, proteins and other biochemical molecules. However, melatonin, an indoleamine, presents in the early life form remains unchanged in its structure from unicellular organisms to mammals. When it was discovered, it was considered to be a neuronal hormone produced exclusively in the pineal gland of vertebrates. The latter discovery of its presence in primitive bacteria drives the melatonin research in different directions. Its primary function is serving as an antioxidant in all organisms. Its chemical structure is perfect to scavenge free radicals and thus, this molecule is preserved from bacteria to mammals. However, this molecule acquired many additional functions during evolution. These include circadian regulation, immuno-enhancement, oncostatic, anti-inflammatory and anti-aging activities. In the review, we are trying to present hypothetical and most plausible chronological events in the functional evolvements of melatonin during the process of evolution.