Copper complexes with bioactive ligands Part I--Antimicrobial activity.

Biological properties of new copper(II) complexes of 2-methylthionicotinate (2-MeSNic) of composition Cu(2-MeSNic)2(MeNia)(2).4H2O (where MeNia is N-methyl-nicotinamide), Cu(2-MeSNic)2(Nia)(2).2H2O (where Nia is nicotinamide) and Cu(2-MeSNic)2L2 (where L is isonicotinamide (iNia) or ethyl nicotinate (EtNic)) are reported. Gram(-)-bacteria (Escherichia coli) are more resistant against Cu(II) complexes than Gram(+)-bacteria (Staphylococcus aureus)--significant antistaphylococcal activity was found with Cu(2-MeSNic)2(MeNia)(2).4H2O (IC50 1.3 mmol/L). Candida parapsilosis was most inhibited by Cu(2-MeSNic)2.H2O and Cu(2-MeSNic)2(MeNia)(2).4H2O (IC50 1.4 mmol/L and 1.5 mmol/L, respectively). Biosynthesis of nucleic acids influenced by Cu(2-MeSNic)2(Nia)(2).2H2O indicated by incorporation of 14C-adenine (IC50(Ade) 0.31 mmol/L) is more sensitive than biosynthesis of proteins indicated by incorporation of 14C-leucine (IC50(Leu) 9.94 mmol/L). Cu(II) complexes with expressed antimicrobial activity showed no mutagenic activity.