Evaluating the Oxidative Stress in Inflammation: Role of Melatonin

Abstract

Oxygen is used by eukaryotic cells for metabolic transformations and energy production in mitochondria. Under physiological conditions, there is a constant endogenous production of intermediates of reactive oxygen (ROI) and nitrogen species (RNI) that interact as signaling molecules in physiological mechanisms. When these species are not eliminated by antioxidants or are produced in excess, oxidative stress arises. Oxidative stress can damage proteins, lipids, DNA, and organelles. It is a process directly linked to inflammation; in fact, inflammatory cells secrete a large number of cytokines and chemokines responsible for the production of ROI and RNI in phagocytic and nonphagocytic cells through the activation of protein kinases signaling. Currently, there is a wide variety of diseases capable of producing inflammatory manifestations. While, in the short term, most of these diseases are not fatal they have a major impact on life quality. Since there is a direct relationship between chronic inflammation and many emerging disorders like cancer, oral diseases, kidney diseases, fibromyalgia, gastrointestinal chronic diseases or rheumatics diseases, the aim of this review is to describe the use and role of melatonin, a hormone secreted by the pineal gland, that works directly and indirectly as a free radical scavenger, like a potent antioxidant.

Keywords: antioxidant; chronic diseases; inflammation; melatonin; oxidative stress.

Figure 1

Biosynthesis of melatonin from tryptophan.

Figure 2

Diagram of the main mechanisms for the development of the oral diseases based on inflammation and oxidative stress: gingivitis and periodontitis and the role of MLT in their inhibition. Positive signs mean induction and negative inhibition. The line explains the cascade of reactions which relates gingivitis with periodontitis and involved exogenous and endogenous factors. The dotted line indicates where the activity of melatonin is targeted.