Phenothiazine: the parent molecule.

Phenothiazine is an aromatic tricyclic compound that first emerged from the furtive chemical activity surrounding the aniline dye industry at the latter half of the 19th century. It contains both nitrogen and sulphur atoms and is the parent molecule of a multitude of drugs that have enjoyed varied and extensive use throughout medical and veterinary practice. The compound itself is not without biological activity and has been shown to possess insecticidal, antifungal, antibacterial and anthelmintic properties. It was this latter vermifugal application that has earned the molecule a place alongside penicillin and DDT for its colossal impact on mankind. Following its extensive usage over many years, unwanted reactions including neuromuscular incoordination, photosensitization and haemolytic anaemia have been reported and these have limited its use in the present climate. Investigations into the mode of action of phenothiazine and its underlying biochemical properties have been undertaken but the molecule has yet to reveal its secrets and still poses problems of understanding at the molecular level. This article reviews the literature, both established and current, and presents a contemporary view on phenothiazine and its interaction with biological systems.