Melatonin As A Barrier Against SARS-CoV-2

Melatonin is a molecule that has a variety of functions. Many clinical trials have examined the therapeutic uses of melatonin. These show melatonin helps prevent cell damage in many states. The benefits of melatonin are through its properties as a potent antioxidant, and antioxidant enzyme inducer as well as stimulating immune functions. This supports the use of melatonin in viral infections, which often have inflammatory effects and increasing oxidative stress. 

Melatonin is synthesized in the pineal gland and is regulated by the circadian clock. The most important factor regulating metabolism is the light/dark cycle. Melatonin is secreted with low levels during the daylight hours and peaks during darkness. Blood concentrations rise during the evening, reaching the highest values between 02:00 and 04:00 am. The levels return to baseline during the late morning.

Results confirming the antioxidant activity of melatonin were obtained in studies performed on respiratory syncytial virus infection. Respiratory Syncytial Virus is a common cause of bronchiolitis, a respiratory tract disease. This disease is characterized by extensive damage to the bronchial epithelial cells and infiltration and activation of inflammatory cells into the airways.

These results suggest melatonin may prevent injury to the airway structure through the inhibition of oxidative stress and the production of proinflammatory cytokines. Melatonin can be a useful therapeutic agent in Respiratory Syncytial Virus-induced pulmonary disease. Evidence shows respiratory disorders induced by viral pathogens result from the generation of reactive oxygen species by inflammatory cells in response to infection. Modulating the inflammatory response of the reactive oxygen species production, and the related oxidative stress represents a potential to improve reactions against viral infections and their consequences.

Melatonin produced in the lungs acts as a barrier against SARS-CoV-2. It does this by blocking the expression of genes encoding proteins in the cells serving as viral entry points. Researchers at the University of São Paulo found melatonin prevented infection of these cells by the virus and inhibits the immune response. They found that the virus remains in the respiratory tract for a few days and then leaves the host. This study is published in Melatonin Research. DOI:10.32794/mr11250090 

The weakness of melatonin is the short half-life and low levels of serum during day hours. Dosages of melatonin in pharmacological concentrations are non-toxic, and the results obtained in vitro and experimental animals support the beneficial immunoregulatory antioxidant role of melatonin.