Melatonin-antioxidant system: what is known in plants, crustaceans and mammals? Perspectives and challenges

Melatonin (N-acetyl-5-methoxytryptamine) is classically known as chemical messenger of darkness. Both plants and animals respond to photoperiodic signals and the harmonization of physiological events with light/dark cues is also well appreciated. It is interesting that plants and invertebrates accumulate melatonin although they are devoid of melatonin producing gland, pineal gland as in vertebrates including mammals. This led to important question related to common cross-kingdom signal molecule. The major goal of this mini-review is to recapitulate biosynthetic aspects and antioxidant property of melatonin in mammals, crustaceans and plants. Based on the available literature, it can be concluded that the synthesis, mode and target sites of melatonin are well documented in vertebrates including mammals and on the other hand, melatonin production pathways are little understood as compared to its antioxidant property in plants whereas, in crustaceans research related to both aspects are not well defined. The overarching point of this review indicates that both edible plants and crustaceans are consumed by humans as their food and obviously benefited from antioxidant, melatonin. Therefore, research towards melanodermic pathways further enhances our understanding into the meaning of melatonin system in edible plants and crustaceans which ultimately fetches human health.