Biological evaluation of a novel amino acid‐based macrocyclic Mn(III) and Fe(III) complexes

Abstract

A new tetradentate ligand 4-benzylidine-1,7-bis(4-hydroxy-3-methoxyphenyl) hepta-1,6-diene-3,5-bis(2-imino-3-phenylpropanoic acid) of the type N 2 O 2 has been synthesized from curcumin derived non-enolisable diketone and L-phenylalanine and complexed with Mn(III) and Fe(III) metal ions. The non-enolisable curcumin was obtained by Knoevenagel condensation. The synthesized ligand and complexes (MnL & FeL) were characterized by various spectral techniques. Using absorption and emission spectral techniques CT-DNA and BSA binding studies has been carried out. The absorption and emission spectral tools reveal the intercalative mode of binding between the CT-DNA and the metal complexes. The fluorescence of BSA was quenched around 340 nm by the metal complexes followed by static quenching mechanism. The emission spectra of BSA were recorded at three different temperatures. The binding sites, mode of binding, binding energy and the donor-acceptor distance on the basis of Forster's resonance energy transfer (FRET) were calculated. The binding site of the metal complexes with CT-DNA and BSA has been discussed by molecular docking studies in order to substantiate the experimental results.

Evaluation of DNA/BSA Binding and Chemical Nuclease Activity of L-Tyrosine-Based Mn(III) and Fe(III) Metallo-Intercalators

“…27 The magnetic moment values of 4.86 BM and 5.91 BM for MnL and FeL, respectively, further confirms the octahedral geometry. 28 The values obtained for molar conductance (51.78 and 51.56) of MnL and FeL complexes, respectively, reveals that the complexes are 1:1 electrolytes. 29…”

“…The increase in complex concentration enhances the DNA viscosity as the base pairs of DNA get separated at its intercalation sites causing increase in the overall DNA length. 35 The viscosity of the DNA increases gradually with increase in complex concentration. These results indicate that both the complexes under study can intercalate the adjacent DNA base pairs, causing an expansion in the helix, and thus enhance the viscosity of DNA.…”