Redox-active metal(II) complexes of sterically hindered phenolic ligands: Antibacterial activity and reduction of cytochrome c

The synthesis and physico-chemical characterization of Fe(II) and Mn(II) complexes of 4,6-di-tert-butyl-3[(2-hydroxyethyl)sulphanyl]-1,2-dihydroxybenzene (HLI) and 2-amino-4,6-di-tert-butylphenol (HLII) were carried out. Antibacterial activity of the Co(II), Fe(II) and Mn(II) complexes was evaluated in comparison with Cu(II) complexes and three common antibiotics; it was found to follow the order: (1) Сu(LI)2 > Сo(LI)2 > Fe(LI)2 ⩾ Mn(LI)2 > HLI; (2) Сu(LII)2 > Сo(LII)2 > HLII > Fe(LII)2 ⩾ Mn(LII)2; and their reducing ability (determined electrochemically) followed the same order. Spectrophotometric investigation was carried out in order to estimate the rate of the reduction of bovine heart сytochrome c with the ligands and their metal(II) complexes. NADPH:cytochrome P450-reductase was found to increase the rate of сytochrome c reduction with HLI and HLII ligands, while adrenodoxin in couple with NAD(P)H: adrenodoxin reductase had no substantial effect thereon. It was shown that the reduction of сytochrome c with these compounds cannot be related solely to the facility of their oxidation оr ionization.

The synthesis, physico-chemical characterization and biological evaluation of Fe(II) and Mn(II) complexes of 4,6-di-tert-butyl-3[(2-hydroxyethyl)sulphanyl]-1,2-dihydroxybenzene (HLI) and 2-amino-4,6-di-tert-butylphenol (HLII) were carried out.Figure optionsDownload as PowerPoint slide