Phenothiazine

Phenothiazine itself is only of theoretical interest, but derivatives of it revolutionized psychiatry, other fields of medicine, and pest management. Other derivatives have been studied for possible use in advanced batteries and fuel cells. Phenothiazine-derived drugs In 1876, methylene blue, a derivative of phenothiazine, was synthesized by Heinrich Caro at BASF. The structure was deduced in 1885 by Heinrich August Bernthsen. Bernthsen synthesized phenothiazine in 1883. and make methicillin-resistant Staphylococcus aureus (MRSA) susceptible to beta-lactam antibiotics. The major reason why thioridazine has not been utilized as an antimicrobial agent is due to adverse effects on the central nervous system and cardiovascular system (particularly QT interval prolongation). Phenothiazine antipsychotics are classified into three groups that differ with respect to the substituent on nitrogen: the aliphatic compounds (bearing acyclic groups), the "piperidines" (bearing piperidine-derived groups), and the piperazine (bearing piperazine-derived substituents). Nondrug applications The synthetic dye methylene blue, containing the structure, was described in 1876. Many water-soluble phenothiazine derivatives, such as methylene blue, methylene green, thionine, and others, can be electropolymerized into conductive polymers used as electrocatalysts for NADH oxidation in enzymatic biosensors and biofuel cells. Phenothiazine is used as an anaerobic inhibitor for acrylic acid polymerization, often used as an in-process inhibitor during the purification of acrylic acid. == Trade names ==

Like many commercially significant compounds, phenothiazine has numerous trade names, including AFI-Tiazin, Agrazine, Antiverm, Biverm, Dibenzothiazine, Orimon, Lethelmin, Souframine, Nemazene, Vermitin, Padophene, Fenoverm, Fentiazine, Contaverm, Fenothiazine, Phenovarm, Ieeno, ENT 38, Helmetina, Helmetine, Penthazine, XL-50, Wurm-thional, Phenegic, Phenovis, Phenoxur, and Reconox. ==Former uses==

Phenothiazine was formerly used as an insecticide and as a drug to treat infections with parasitic worms (anthelminthic) in livestock and people, but its use for those purposes has been superseded by other chemicals. Phenothiazine was introduced by DuPont as an insecticide in 1935. About 3,500,000 pounds were sold in the US in 1944. However, because it was degraded by sunlight and air, it was difficult to determine how much to use in the field, and its use waned in the 1940s with the arrival of new pesticides like DDT that were more durable. As of July 2015 it is not registered for pesticide use in the US, Europe, or Australia. As an anthelminthic It was introduced as anthelminthic in livestock in 1940 and is considered, with thiabendazole, to be the first modern anthelminthic. The first instances of resistance were noted in 1961. Uses for this purpose in the US are still described but it has "virtually disappeared from the market." In the 1940s it also was introduced as antihelminthic for humans; since it was often given to children, the drug was often sold in chocolate, leading to the popular name, "worm chocolate." Phenothiazine was superseded by other drugs in the 1950s. == Structure and synthesis==

The central C4SN ring is folded in phenothiazines. The compound was originally prepared by Bernthsen in 1883 via the reaction of diphenylamine with sulfur, but more recent syntheses rely on the cyclization of 2-substituted diphenyl sulfides. Few pharmaceutically significant phenothiazines are prepared from phenothiazine, although some of them are. Phenothiazines are electron donors, forming charge-transfer salts with many acceptors. == References ==