Antibacterial and antifungal evaluation of some chalcogen bearing ligands, their transition and nontransition metal complexes

Abstract

Eight chalcogen bearing compounds, 3-(4-fluorophenyl telluro) propylamine (1), 3-(phenyl telluro)propylammonium acetate salt (2), 3-(phenyl telluro)propylacetamide (3) and α-(phenylseleno) acetic acid (4) (1-4 are ligands), [Ph2Sn(Cl).1](NO3 ) (5), [Ph3Sn.1](BPh4 ) (6), [ZnCl2 .2] (7) and [CdCl2.2] (8) (5-8 are complexes of 1 and 2) were synthesised and screened for antibacterial activity against Gram-positive bacterial strains of Staphylococcus aureus, Bacillus anthracis and the Gramnegative bacteria Escherchia coli. They were also tested for their antifungal activity against Candida tropicalis, Trichophyton rubrum and Asperegillus niger, by using the disk diffusion technique. Inhibition zones demonstrated that compounds 1–3 showed significant activity, due to the presence of N in the form of amine group however Compound 4 bearing an acidic group, shows higher activity against bacterial strains. Compounds 5–8 (having Sn, Zn and Cd in their framework) showed still higher activities, due to increase in the lipophilicity and easier penetration of the compounds into the outer cell wall of the microorganisms, which causes death due to cell membrane rupturing. Compounds 1–8 were most effective against E. coli (bacterial strains), as the cell wall of Gram-negative strains have thin outer lipid membrane, which is made up of lipopolysaccharides. These compounds showed slightly reduced antifungal activity, because the cell wall of fungi is made up of chitin, which is difficult to cross. It could be concluded, from the obtained results that the biological activity of compounds is essentially determined by the number and nature of the organic groups and central metal ion. The presence of NH2, COOH group as well as metal ion like Sn, Zn, Cd in the compounds leads to higher activity.