Apocynin

Apocynin, also known as acetovanillone, is a natural organic compound structurally related to vanillin. It has been isolated from a variety of plant sources and is being studied for its variety of pharmacological properties. Apocynin, also known as acetovanillone, is a natural organic compound structurally related to vanillin. It has been isolated from a variety of plant sources and is being studied for its variety of pharmacological properties. Apocynin was first described by Oswald Schmiedeberg, a German pharmacologist, in 1883 and was first isolated by Horace Finnemore, in 1908, from the root of Canadian hemp (Apocynum cannabinum). At the time, this plant was already used for its known effectiveness against edema and heart problems. In 1971, apocynin was also isolated from Picrorhiza kurroa, a small plant that grows at high altitudes in the western Himalayas. P. kurroa was used for ages as a treatment for liver and heart problems, jaundice, and asthma. In 1990, Simons et al. isolated apocynin to a pharmacologically useful level using an actively guided isolation procedure. Apocynin's observed anti-inflammatory capabilities proved to be a result of its ability to selectively prevent the formation of free radicals, oxygen ions, and peroxides in the body. Apocynin has since been extensively studied to help determine its disease-fighting capabilities and applications. Apocynin is a solid with a melting point of 115 °C and the faint odor of vanilla. It is soluble in hot water, alcohol, benzene, chloroform, and ether. NADPH oxidase is an enzyme that effectively reduces O2 to superoxide (O2–•), which can be used by the immune system to kill bacteria and fungi. Apocynin is an inhibitor of NADPH oxidase activity and thus is effective in preventing the production of the superoxide in human white blood cells or neutrophilic granulocytes. It does not however obstruct the phagocytic or other defense roles of granulocytes. Due to the selectivity of its inhibition, apocynin can be widely used as an inhibitor of NADPH oxidase without interfering in other aspects of the immune system. Apocynin was used to determine whether ionic activation due to proton flux across the membrane of renal medulla cells was coupled to NADPH oxidase production of superoxide. Apocynin was introduced to the cells and completely blocked the production of superoxide, and was a key component in determining that the proton outflow was responsible for the activation of NADPH oxidase. The mechanism of action of apocynin is not understood yet. In the experimental studies, apocynin is shown to dimerize and form diapocynin. Although, diapocynin seems to have beneficial effect in reducing reactive oxygen species and anti-inflammatory properties, it is still yet to be shown as biologically relevant molecule. Biotransformation of apocynin predominantly leads to glycosylated form of apocynin. Another molecule that is shown to form under experimental conditions is nitroapocynin. Small scale early stage clinical trials for apocynin were conducted for chronic obstructive pulmonary disease (COPD) in 2011 and asthma in 2012 but they did not progress any further.