Novel broad-spectrum metal-based antifungal agents. Correlations amongst the structural and biological properties of copper (II) 2-acetylpyridine N4-dialkylthiosemicarbazones

Copper(II) complexes of the type [Cu(L)X], where L = tridentate anion of 2-acetylpyridine N4-diethyl thiosemicarbazone and X = C1 or Br, were screened against seven fungal strains pathogenic to man viz. Aspergillus niger, Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Tricophyton rubrum, Epidermophyton floccosum and Microsporum canis. The greater growth inhibition exhibited by the bromo complex can be explained on the basis of its lower Cu(II)/Cu(I) redox couple and greater covalent bonding. These compounds represent a novel class of metal-based antifungal agents which provide opportunities for a large number of synthetic variations for modulation of the activities.