In vitro antimicrobial and antioxidant studies on N-(2- hydroxylbenzylidene) pyridine -2-amine and its M(II) complexes

Abstract

A tridentate ligand N–(2–hydroxybenzylidene)pyridine–2–amine has been prepared by condensation of salicylaldehyde and  2–aminopyridine in absolute ethanol. M(II) complexes (M= Mn and Ni) of the ligand were also prepared, recovered by filtration and purified by recrystallization in absolute methanol. Characterization of the prepared compounds was done on the basis of FTIR spectroscopy, solubility test, melting  point/decomposition temperature, conductivity and magnetic susceptibility measurements. Job’s method of continuous variation was used to determine the number of ligands coordinated to the metal ions. The result indicated 1:2 Metal (II) to ligand ratio in both the complexes. Appearance of a sharp peak at 1596cm-1 in the FTIR spectra of the ligand indicated the formation of the azomethine (-C=N-) bond. This peak shifted to lower frequencies (1590 cm-1 and 1557 cm-1) in the spectra of the Mn2+ and Ni2+ complexes respectively due to coordination of the azomethine nitrogen to the metal ions. Antimicrobial activities of the ligand and the complexes were studied on Staphylococcus aureus,  Escherichia coli, Klebsiella pneumonia, Aspergillus funigathus and Mucor sp. isolates using disc diffusion method. The results obtained indicated that the test compounds are active against most of the tested isolates. Antioxidant activity of the compounds was tested using 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging method. The lower IC50 value (2.27 μg/ml) obtained in the ligand, by probit analysis using SPSS 16.0, indicates its high antioxidant property.

Keywords: Salicylaldehyde, Azomethine, Reflux, Antimicrobial and Antioxidant.