Cyclooxygenase (COX), officially known as prostaglandin-endoperoxide synthase (PTGS), is an enzyme that is responsible for formation of important biological mediators called prostanoids, including prostaglandins, prostacyclin and thromboxane. Pharmacological inhibition of COX can provide relief from the symptoms of inflammation and pain. Drugs, like Aspirin, that inhibit cyclooxygenase activity have been available to the public for about 100 years. Two cyclooxygenase isoforms have been identified and are referred to as COX-1 and COX-2. Under many circumstances the COX-1 enzyme is produced constitutively (i.e., gastric mucosa) whereas COX-2 is inducible (i.e., sites of inflammation). Non-steroidal anti-inflammatory drugs (NSAID), such as aspirin and ibuprofen, exert their effects through inhibition of COX. The main COX inhibitors are the non-steroidal anti-inflammatory drugs (NSAIDs).
Acetaminophen (paracetamol) is a selective cyclooxygenase-2 (COX-2) inhibitor with an IC50 of 25.8 μM; is a widely used antipyretic and analgesic drug.
Indomethacin is a potent and nonselective inhibitor of COX1 and COX2, with IC50s of 18 nM and 26 nM for human COX-1 and COX-2, respectively, in CHO cells.
Paradol is a pungent phenolic substance found in ginger and other Zingiberaceae plants. Paradol is an effective inhibitor of tumor promotion in mouse skin carcinogenesis, binds to cyclooxygenase (COX)-2 active site.
Ginsenoside C-K, a bacterial metabolite of G-Rb1, exhibits anti-inflammatory effects by reducing iNOS and COX-2. Ginsenoside C-K exhibits an inhibition against the activity of CYP2C9 and CYP2A6 in human liver microsomes with IC50s of 32.0±3.6 μM and 63.6±4.2 μM, respectively.
Diclofenac is a potent and nonselective anti-inflammatory agent, acts as a COX inhibitor, with IC50s of 4 nM, 1.3 nM for human COX-1 and COX-2 in CHO cells, and 5.1, 0.84 μM for ovine COX-1 and COX-2, respectively.
Xanthohumol is one of the principal flavonoids isolated from hops, the inhibitor of diacylglycerol acetyltransferase (DGAT), COX-1 and COX-2, and shows anti-cancer and anti-angiogenic activities.
Ginsenoside Rg3 is the main component of Red ginseng. Ginsenoside Rg3 inhibits Na+ and hKv1.4 channel with IC50s of 32.2±4.5 and 32.6±2.2 μM, respectively. Ginsenoside Rg3 also inhibits Aβ levels, NF-κB activity, and COX-2 expression.
NS-398 is a non-steroidal an-inflammatory agent with analgesic and antipyretic effects, and selectively inhibits prostaglandin G/H synthase 2/cyclooxygenase 2 (COX-2) activity, with an IC50 of 3.8 μM, and has no effect on COX-1 at 100 μM.
Carprofen is a nonsteroid anti-inflammatory agent, acts as a multi-target FAAH/COX inhibitor, with IC50s of 3.9 μM, 22.3 μM and 78.6 μM for COX-2, COX-1 and FAAH, respectively.
(-)-Epicatechin inhibits cyclooxygenase-1 (COX-1) with an IC50 of 3.2 μM. (-)-Epicatechin inhibits the IL-1β-induced expression of iNOS by blocking the nuclear localization of the p65 subunit of NF-κB.
Rofecoxib is a potent, specific and orally active COX-2 inhibitor, with IC50s of 26 and 18 nM for human COX-2 in human osteosarcoma cells and Chinese hamster ovary cells, with a 1000-fold selectivity for COX-2 over human COX-1 (IC50 > 50 μM in U937 cells and > 15 μM in Chinese hamster ovary cells).
