Melatonin as a microenvironmental cue for parasite development inside the host

Throughout the evolutionary process, parasites have acquired characteristics that function as survival mechanisms. It has been reported that melatonin, a molecule present in virtually all living organisms, has several roles in parasite biology such as preventing tissue damage, regulating gene expression and inflammatory processes, and acting as a free radical scavenger.  Additionally, melatonin produced by the hosts accelerates the intra-erythrocytic cycle of the human malaria parasite Plasmodium falciparum and the rodent malaria parasite P. chabaudi, respectively. These findings have recently led to an increased research enthusiasm to find how melatonin influences the biological cycle of parasites. Therefore, this review aims to gather and analyze the potential relationships of host produced melatonin with the parasites Plasmodium sp., Trypanosoma cruzi, Leishmania spp., Toxoplasma gondii, Schistosoma mansoni, Opisthorchis viverrini, and Entamoeba histolytica, respectively.