Abstract:
Zinc(II), copper(II), nickel(II) and cobalt(II) complexes of Schiff-bases, obtained by the
condensation of 3 rd generation Cephalosporin e.g., Ceftriaxone, Cefixime, Cefotaxime,
and Ceftazidime with the respective aldehydes such as furyl-2-carboxaldehyde,
thiophene-2-carboxaldehyde,
salicylaldehyde,
pyrrol-2-carboxaldehyde
and
3-
hydroxynaphthalene-2-carboxaldehyde were synthesized and characterized by their
physical, molar conductance, magnetic moments, and electronic spectral measurements
(IR, 1 H and
13
C NMR and mass), analytical (CHN analysis) and thermal analyses data.
Analytical data and electrical conductivity measurements indicated the formation of M:L
(1:2) complexes of the type [M(L) 2 (H 2 O) 2 ] or [M(L) 2 (H 2 O) 2 ]Cl 2 [where M = Zn(II),
Cu(II), Ni(II) and Co(II)] in which ligands act as bidentate towards divalent metal ions
via azomethine-N and deprotonated-O of salicyl and naphthyal, furanyl-O, thienyl-S and
XIIIdeprotonated pyrrolyl-N. The magnetic moments and electronic spectral data suggest
octahedral geometry for these complexes.
The main objective of present study is to highlight the potential of Cephalosporin
derivatives as antimicrobial agents. The work comprises of the study of changes in
antimicrobial activity of four cephalosporins, Ceftiaxone, Cefixime, Cefotaxime and
ceftazidime by condensation of free amino group (NH 2 ) of these Cephalosporin with the
carbonyl (HC=O) group of aldehydes to achieve the target of twenty new Cephalosporin
derived Schiff bases (L 1 )-(L 20 ) and their metal complexation with Zn(II). Cu(II), Ni(II),
Co(II) salts. The synthesized ligands, along with their metal complexes were screened
for their antibacterial activity against different Gram-positive & Gram-negative
(Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, Pseudomonas
aeruginosa, Salmonella enteritidis and Klebsiella pneumonia) bacterial strains using
agar-well diffusion method. The minimum inhibitory concentration (MIC) was observed
and thereafter compared with the standard MIC’s of the respective drug by agar dilution
method against both Gram positive and Gram-negative organisms so as to evaluate
changes in antimicrobiological activity of the standard cephalosporins after azomethine
formation with aldehydes and their metal interactions. The results of these studies show
the metal complexes to be more antibacterial against one or more species as compared to
the uncomplexed ligands. It was concluded that metal elements that are essential for our
body mechanism either present in the body or coadminstered with vitamins markedly
influence the MIC’s of antibiotics by producing synergism or antagonism.