The Role of Plant-Based Natural Compounds in Inflammation

Arachidonic acid is converted by cyclooxygenases (COXs), microsomal prostaglandin E synthase-1 (mPGES-1) and lipoxygenases (LOXs) into a variety of eicosanoids that mediate inflammatory reactions. COXs and mPGES-1 catalyze the biosynthesis of prostanoids, which are overproduced in inflamed tissue. In the case of LOXs, namely 5-lipoxygenase (5-LOX) catalyzes the biosynthesis of several leukotrienes, from which especially leukotriene B4 (LTB4) is overproduced in several inflammatory diseases. COX enzymes have been one of the most studied therapeutic targets in human history, revealing initially the first-generation COX inhibitors called non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs are the most prescribed drugs worldwide, used to relieve pain, fever and inflammation. The increasing knowledge on inflammatory processes resulted in the reconsideration of the importance of inflammatory targets with the focus turning toward dual 5-LOX/COX-2 and 5-LOX/mPGES-1 inhibitors. In addition, the importance of inflammatory enzymes was recognized in several other diseases such as cancer and cardiovascular and neurodegenerative diseases. Plants are rich sources of natural compounds with original structures and interesting biological activities. Therefore, the search for novel plant-derived compounds regulating inflammation processes may contribute to the development of new and safer drugs for inflammatory diseases or diseases accompanied by inflammation raised by eicosanoids.