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Cyclooxygenase
Cyclooxygenase (COX), officially known as prostaglandin-endoperoxide synthase (PTGS), is an enzyme (specifically, a family of isozymes, ) that is responsible for biosynthesis of prostanoids, including thromboxane and prostaglandins such as prostacyclin, from arachidonic acid. A member of the animal-type heme peroxidase family, it is also known as prostaglandin G/H synthase. The specific reaction catalyzed is the conversion from arachidonic acid to prostaglandin H2 via a short-living prostaglandin G2 intermediate. Pharmaceutical inhibition of COX can provide relief from the symptoms of inflammation and pain. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, exert their effects through inhibition of COX. Those that are specific to the COX-2 isozyme are called COX-2 inhibitors. The active metabolite ( AM404) of paracetamol is a COX inhibitor, a fact to which some or all of its therapeutic effect has been attributed. In medicine, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PTGS1
Cyclooxygenase 1 (COX-1), also known as prostaglandin-endoperoxide synthase 1 ( HUGO PTGS1), is an enzyme that in humans is encoded by the ''PTGS1'' gene. In humans it is one of three cyclooxygenases. History Cyclooxygenase (COX) is the central enzyme in the biosynthetic pathway to prostaglandins from arachidonic acid. This protein was isolated more than 40 years ago and cloned in 1988. Gene and isozymes There are two isozymes of COX encoded by distinct gene products: a constitutive COX-1 (this enzyme) and an inducible COX-2, which differ in their regulation of expression and tissue distribution. The expression of these two transcripts is differentially regulated by relevant cytokines and growth factors. This gene encodes COX-1, which regulates angiogenesis in endothelial cells. COX-1 is also involved in cell signaling and maintaining tissue homeostasis. A splice variant of COX-1 termed COX-3 was identified in the central nervous system of dogs, but does not result in a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COX-2
Cyclooxygenase-2 (COX-2), also known as prostaglandin-endoperoxide synthase 2 ( HUGO PTGS2), is an enzyme that in humans is encoded by the ''PTGS2'' gene. In humans it is one of three cyclooxygenases. It is involved in the conversion of arachidonic acid to prostaglandin H2, an important precursor of prostacyclin, which is expressed in inflammation. Function PTGS2 (COX-2), converts arachidonic acid (AA) to prostaglandin endoperoxide H2. PTGSs are targets for NSAIDs and PTGS2 (COX-2) specific inhibitors called coxibs. PTGS-2 is a sequence homodimer. Each monomer of the enzyme has a peroxidase and a PTGS (COX) active site. The PTGS (COX) enzymes catalyze the conversion of AA to prostaglandins in two steps. First, hydrogen is abstracted from carbon 13 of arachidonic acid, and then two molecules of oxygen are added by the PTGS2 (COX-2), giving PGG2. Second, PGG2 is reduced to PGH2 in the peroxidase active site. The synthesized PGH2 is converted to prostaglandins ( PGD2, PG ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COX-2 Inhibitor
Cyclooxygenase-2 inhibitors (COX-2 inhibitors), also known as coxibs, are a type of nonsteroidal anti-inflammatory drug (NSAID) that directly target cyclooxygenase-2 (COX-2), an enzyme responsible for inflammation and pain. Targeting selectivity for COX-2 reduces the risk of peptic ulceration and is the main feature of celecoxib, rofecoxib, and other members of this drug class. After several COX-2–inhibiting drugs were approved for marketing, data from clinical trials revealed that COX-2 inhibitors caused a significant increase in heart attacks and strokes, with some drugs in the class having worse risks than others. Rofecoxib (sold under the brand name Vioxx) was taken off the market in 2004 because of these concerns, while celecoxib (sold under the brand name Celebrex) and traditional NSAIDs received boxed warnings on their labels. Many COX-2–specific inhibitors have been removed from the US market. As of December 2011, only Celebrex (celecoxib) is still available for purc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonsteroidal Anti-inflammatory Drug
Non-steroidal anti-inflammatory drugs (NSAID) are members of a Indication (medicine), therapeutic drug class which Analgesic, reduces pain, Anti-inflammatory, decreases inflammation, Antipyretic, decreases fever, and Antithrombotic, prevents blood clots. Side effects depend on the specific drug, its dose and duration of use, but largely include an increased risk of Stomach ulcers, gastrointestinal ulcers and bleeds, heart attack, and kidney disease. The term ''non-steroidal'', common from around 1960, distinguishes these drugs from corticosteroids, another class of anti-inflammatory drugs, which during the 1950s had acquired a bad reputation due to overuse and side-effect problems after their introduction in 1948. NSAIDs work by inhibiting the activity of cyclooxygenase enzymes (the COX-1 and COX-2 isozyme, isoenzymes). In cells, these enzymes are involved in the synthesis of key biological mediators, namely prostaglandins, which are involved in inflammation, and thromboxanes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ibuprofen
Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that is used to relieve pain, fever, and inflammation. This includes dysmenorrhea, painful menstrual periods, migraines, and rheumatoid arthritis. It can be taken oral administration, orally (by mouth) or Intravenous therapy, intravenously. It typically begins working within an hour. Common side effects include heartburn, nausea, indigestion, and abdominal pain. Potential side effects include gastrointestinal bleeding. Long-term use has been associated with kidney failure, and rarely liver failure, and it can exacerbate the condition of people with heart failure. At low doses, it does not appear to increase the risk of myocardial infarction (heart attack); however, at higher doses it may. Ibuprofen can also worsen asthma. While its safety in early pregnancy is unclear, it appears to be harmful in later pregnancy, so it is not recommended during that period. It works by inhibiting the production of prostaglandins by dec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspirin
Aspirin () is the genericized trademark for acetylsalicylic acid (ASA), a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic. Specific inflammatory conditions that aspirin is used to treat include Kawasaki disease, pericarditis, and rheumatic fever. Aspirin is also used long-term to help prevent further heart attacks, ischaemic strokes, and blood clots in people at high risk. For pain or fever, effects typically begin within 30 minutes. Aspirin works similarly to other NSAIDs but also suppresses the normal functioning of platelets. One common adverse effect is an upset stomach. More significant side effects include stomach ulcers, stomach bleeding, and worsening asthma. Bleeding risk is greater among those who are older, drink alcohol, take other NSAIDs, or are on other blood thinners. Aspirin is not recommended in the last part of pregnancy. It is not generally recommended in children with infections ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin
Prostaglandins (PG) are a group of physiology, physiologically active lipid compounds called eicosanoids that have diverse hormone-like effects in animals. Prostaglandins have been found in almost every Tissue (biology), tissue in humans and other animals. They are derived enzymatically from the fatty acid arachidonic acid. Every prostaglandin contains 20 carbon atoms, including a carbon ring, 5-carbon ring. They are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives. The structural differences between prostaglandins account for their different biological activities. A given prostaglandin may have different and even opposite effects in different tissues in some cases. The ability of the same prostaglandin to stimulate a reaction in one tissue and inhibit the same reaction in another tissue is determined by the type of receptor (biochemistry), receptor to which the prostaglandin binds. They act as autocrine or paracrine factors with their target cells ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostacyclin
Prostacyclin (also called prostaglandin I2 or PGI2) is a prostaglandin member of the eicosanoid family of lipid molecules. It inhibits platelet activation and is also an effective vasodilator. When used as a drug, it is also known as epoprostenol. The terms are sometimes used interchangeably. Function Prostacyclin chiefly prevents formation of the platelet plug involved in primary hemostasis (a part of blood clot formation). It does this by inhibiting platelet activation. It is also an effective vasodilator. Prostacyclin's interactions contrast with those of thromboxane (TXA2), another eicosanoid. Both molecules are derived from arachidonic acid, and work together with opposite platelet aggregatory effects. These strongly suggest a mechanism of cardiovascular homeostasis between these two hormones in relation to vascular damage. Medical uses It is used to treat pulmonary arterial hypertension (PAH), pulmonary fibrosis, as well as atherosclerosis. Prostacyclins are given to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Heme-dependent Peroxidases
Animal heme-dependent peroxidases is a family of peroxidases. Peroxidases are found in bacteria, fungi, plants and animals. On the basis of sequence similarity, a number of animal heme peroxidases can be categorized as members of a superfamily: myeloperoxidase (MPO); eosinophil peroxidase (EPO); lactoperoxidase (LPO); thyroid peroxidase (TPO); prostaglandin H synthase (PGHS); and peroxidasin. Function Myeloperoxidase (MPO) plays a major role in the oxygen-dependent microbicidal system of neutrophils. EPO from eosinophilic granulocytes participates in immunological reactions, and potentiates tumor necrosis factor (TNF) production and hydrogen peroxide release by human monocyte-derived macrophages. MPO (and possibly EPO) primarily use Cl−ions and H2O2 to form hypochlorous acid (HOCl), which can effectively kill bacteria or parasites. In secreted fluids, LPO catalyses the oxidation of thiocyanate ions (SCN−) by H2O2, producing the weak oxidizing agent hypothiocyanite (OSCN−), wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin H2
Prostaglandin H2 (PGH2), or prostaglandin H2 (PGH2), is a type of prostaglandin and a precursor for many other biologically significant molecules. It is synthesized from arachidonic acid in a reaction catalyzed by a cyclooxygenase enzyme. The conversion from arachidonic acid to prostaglandin H2 is a two-step process. First, COX-1 catalyzes the addition of two free oxygens to form the 1,2-dioxane bridge and a peroxide functional group to form prostaglandin G2 (PGG2). Second, COX-2 reduces the peroxide functional group to a secondary alcohol, forming prostaglandin H2. Other peroxidases like hydroquinone have been observed to reduce PGG2 to PGH2. PGH2 is unstable at room temperature, with a half life of 90–100 seconds, so it is often converted into a different prostaglandin. It is acted upon by: * prostacyclin synthase to create prostacyclin * thromboxane-A synthase to create thromboxane A2 and 12-(S)-hydroxy-5Z,8E,10E-heptadecatrienoic acid (HHT) (see 12-Hydroxyheptadecatri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arachidonic Acid
Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega−6 fatty acid 20:4(ω−6), or 20:4(5,8,11,14). It is a precursor in the formation of leukotrienes, prostaglandins, and thromboxanes. Together with omega−3 fatty acids and other omega−6 fatty acids, arachidonic acid provides energy for body functions, contributes to cell membrane structure, and participates in the synthesis of eicosanoids, which have numerous roles in physiology as signaling molecules. Its name derives from the ancient Greek neologism ''arachis'' 'peanut', although peanut oil does not contain any arachidonic acid. Arachidonate is the name of the derived carboxylate anion ( conjugate base of the acid), salts, and some esters. Chemistry In chemical structure, arachidonic acid is a carboxylic acid with a 20-carbon chain and four '' cis''- double bonds; the first double bond is located at the sixth carbon from the omega end. Some chemistry sources define 'arachidonic acid' to designa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
