Antifungal Activity of Some Thiosemicarbazones and Their Copper Complexes.

An extensive literature has developed in recent years in the field of chelate compounds with special reference to their antimicrobial properties. Thus, for example, the copper chelate of oxine (8-hydroxyquinoline) has been the subject of numerous investigations (Hollingshead, 1956). Thiosemicarbazones (TSC), which are compounds capable of forming chelates, have been investigated by Domagk (1950) who found p-acetamidoand p-methoxybenzaldehyde TSC to be antitubercular, while subsequent investigations by a number of workers (Hoggarth et al., 1949; Donovick et al., 1950; Hamre, Bernstein, and Donovick, 1950; Mascitelli-Coriandoli and Maiocchi, 1955) have shown other TSC to be antimycobacterial. It has been suggested by Gausman et al. (1953) that the activity of these compounds is due to their property of forming chelates with metals. This property of TSC has been used as the basis of a method for the quantitative determination of a number of metals (Guha Sircar and Satpathy, 1954). It was considered that the chelates of TSC with metals such as copper may have antifungal properties through a mechanism similar to that of the copper chelate of oxine (8-hydroxyquinoline), which is known to be an effective textile preservative. To study this possibility, a number of TSC having aliphatic and aromatic substituents, respectively, together with their copper complexes, were prepared and their antifungal activity toward two organisms was determined by two methods. For purposes of comparison two commercial fungicides were also examined.