Cyclooxygenase (Prostaglandin-endoperoxide synthase) (COX)

Cyclooxygenase (COX), formally known as prostaglandin-endoperoxide synthase (PTGS), is a bifunctional enzyme that plays a critical role in the biosynthesis of prostanoids, including prostaglandins, prostacyclin, and thromboxane [1][2]. It catalyzes the conversion of arachidonic acid into prostaglandin H2 (PGH2) through two distinct steps: a cyclooxygenase reaction and a peroxidase reaction [3]. In humans, the enzyme exists in two main isoforms: COX-1, which is constitutively expressed in most tissues to maintain physiological functions like gastric mucosal integrity and platelet aggregation, and COX-2, which is primarily induced by inflammatory stimuli [1][4]. Because prostanoids are key mediators of pain, fever, and inflammation, COX enzymes are the primary therapeutic targets for nonsteroidal anti-inflammatory drugs (NSAIDs) [1]. Non-selective NSAIDs like ibuprofen and naproxen inhibit both isoforms, whereas selective inhibitors like celecoxib target COX-2 to minimize gastrointestinal side effects associated with COX-1 inhibition [5]. However, modulation of these enzymes requires careful management due to potential risks, including gastrointestinal bleeding and adverse cardiovascular events such as myocardial infarction or stroke [1][5]. Beyond its role in acute inflammation, COX activity is also implicated in the progression of certain cancers, particularly colorectal cancer, and neurodegenerative diseases [2][4]. The "unspecified isoform" designation typically refers to pharmacological contexts where a drug's activity across COX-1 and COX-2 is either combined or not specifically distinguished [1].

Other names

Prostaglandin G/H synthasePTGSPGHSCyclo-oxygenase

Inhibition of the cyclooxygenase activity of the enzyme, preventing the conversion of arachidonic acid to prostaglandin G2 and subsequently prostaglandin H2, which serves as the precursor for various inflammatory mediators.