Antioxidants and inflammatory disease: Synthetic and natural antioxidants with anti-inflammatory activity

Oxidants play a significant role in the pathogenesis of a number of disorders such as inflammation, rheumatoid arthritis, asthma, psoriasis and contact dermatitis leading to oxidative stress. Oxidative stress may be defined as an imbalance between cellular production of reactive oxygen species (ROS) and antioxidant defense mechanisms. ROS (e.g., superoxide radical, peroxynitryl, hydroxyl radical and hydrogen peroxide) are constantly produced as a result of metabolic reactions in living systems. The aim of this review is to describe recent developments in the study of antioxidants and their role in preventing the formation of ROS. The processes associated with inflammatory responses are complex and often involve ROS. There are many mediators, which initiate and amplify the inflammatory response such as histamine, serotonin, pro-inflammatory cytokines (interleukin-1B (IL-1b) and tumor necrosis factor (TNF-alpha)), inflammatory cells (leukotrienes, macrophages), metabolic products of arachidonic acid (thomboxane A(2), prostaglandins and leukotrienes). The first part of this review focuses on the role of ROS in inflammation. The second part concerns synthetic antioxidants with anti inflammatory activity, and the third part addresses naturally occurring antioxidants with anti inflammatory activity.