ABSTRACT
Even though oxygen and nitrogen are essential and necessary to every aerobic organism, they also have some potentially harmful effects. Oxygen is involved in the production of reactive oxidative species (ROS) and nitrogen in the production of reactive nitrogen species (RNS). Increases in ROS/RNS can cause an imbalance in cell redox reactions, leading to oxidative stress (Augustyniak et al. 2010). At low levels, ROS play important roles by acting as secondary messengers for signal transduction pathways associated with cell growth and differentiation. Production of ROS above normal physiological levels can damage lipids, proteins, and DNA leading to cellular injury (Nagababu et al. 2010).
Oxidative stress is thought to underlie disease and dysfunction in tissues (Deletioglu et al. 2015). It is a common process and is combated in the human body by antioxidant defenses mechanisms. Antioxidants are substances that hinder reactions of free radicals, species that contain one or more unpaired electrons (Powell 2000). ROS and RNS are two important free radicals in aerobic organisms that can cause molecules to become highly reactive (Ruttkay-Nedecky et al. 2013).
This chapter introduces several categories of antioxidants, including endogenous vitamins, phenolics, and minerals, and their mechanisms of actions. Maintaining homeostasis within the cell is critical for cellular functions and antioxidants play an important role in this process.
