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.

History
Apocynin was first described by Oswald Schmiedeberg, a German pharmacologist in 1883 and was first isolated from the root 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.

Physical properties
Apocynin is a solid with a melting point of 115° C and the faint odor of vanilla. It is souble hot water, alcohol, benzene, chloroform, and ether.

Mode of action
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. Apoycnin 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. Apoycnin 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.

Potential use in medical treatments

 * Anti-arthritic: Neutrophils are a key component of the pathogenesis of collagen induced arthritis and in the mechanisms that lead to the start of inflammation of the joints. The action of apocynin reduces the presence of such cells before the inflammation has begun but it is unable to reverse inflammation that is already present.
 * Bowel disease: Apocynin treatment in rats has been proven to lessen damage in the colon as wells as the enzymatic activity of myeloperoxidase which is associated with inflammation. In addition, apocynin also decreased the number of macrophages and polymorphonuclear leukocytes in the colon.
 * Anti-asthmatic: The glucoside of apocynin, androsen, is being investigated for the treatment of asthma for has been shown to prevent bronchial obstruction in guinea pigs. It is believed that the anti-asthmatic quality of apocynin comes from its interference with certain inflammatory processes.
 * Atherosclerosis: Apocynin is used in the treatment of atherosclerosis in order to prevent the activity of NADPH oxidase activity, halting the production of reactive oxidative species. In effect, this inhibition stops initiation of disease in the endothelial cells.