ABSTRACT
ABSTRACT Melatonin hormone (N-acetyl-5-methoxytryptamine) is produced by the pineal gland and plays an important protective role for humans. Many of the benets of melatonin and its metabolites are related to their antioxidant, anti-inammatory, and prooxidative effects. Melatonin has been shown to act on human phagocytes as well as rat splenic macrophages, and may be considered a potent immunomodulator at physiological concentrations. It can stimulate natural immunity, which is an important defense against microbial infections. This molecule is also present in different plants and is denominated phytomelatonin. Its presence in edible and medicinal plants calls for attention due to the possible effect of exogenous melatonin on human physiology, related to sleep and other functions correlated to circadian rhythm. Phytomelatonin concentrations vary from the order of pictograms to micrograms per gram, detected by different techniques. Many melatonin-rich plants in the diet are Eurasian in origin, such as tart cherry, red wine grape, and oat, but some are from America, such as tomato, pineapple, and corn. Investigations into the traditional knowledge of tea infusions and other homemade remedies in the induction of sleep have revealed the presence of phytomelatonin in medicinal plants from China and some other countries. Some native medicinal plants in Brazil might also have phytomelatonin. These plants belong to a rich ora, in many cases endemic to the biomes of the Amazon, Cerrado, and Mata Atlântica, that are now under pressure from deforestation. Previous studies have shown that several melatoninrich medicinal plants have the ability to induce immune system activation and display benecial effects against diseases. This chapter attempts to evaluate the potential presence of phytomelatonin in Brazilian ora and its relation to medicinal use, and to evidence the main effects of this hormone’s associated plants on human health.
