Title
Molecular hybridization approach of bio-potent CuII/ZnII complexes derived from N, O donor bidentate imine scaffolds: Synthesis, spectral, human serum albumin binding, antioxidant and antibacterial studies
Author
Mohammad Shakir, Summaiya Hanif, Md. Fazle Alam, Hina Younus
Year
2016
Journal
Journal of Photochemistry and Photobiology B: Biology
Abstract
Novel bio-relevant monometallic Schiff base complexes of the type, [Cu(L1)2] (1), [Zn(L1)2]·2H2O (2), [Cu(L2)2]·2H2O (3) and [Zn(L2)2]·H2O (4) [L1double bond; length as m-dash(E)-3-(((3-chloro-4-hydroxyphenyl)imino)methyl)naphthalen-2-ol and L2double bond; length as m-dash(E)-2-chloro-4-((1-(5-chloro-2-hydroxyphenyl)ethylidene)amino)phenol] were synthesized and characterized. A comparative account of analytical, spectroscopic (FT-IR, 1H and 13C NMR, Mass, UV–vis and EPR), thermal (TGA/DTA), XRD and SEM studies revealed a correlation between the structure and function of these biologically active molecular entities. HSA (Human serum albumin) binding profiles of the metal complexes (1–4) were monitored using biophysical techniques viz., absorbance, fluorescence, circular dichromism (CD) and foster resonance energy transfer (FRET). The intrinsic binding constant (Kb) demonstrated substantial binding propensity of L1 linked complexes (1 and 2) in comparison to L2 complexes (3 and 4) suggesting L1 to be more bio-active pharmacophore due to higher planarity and conjugation as compared to L2 ligand. The outcome of fluorescence study revealed static quenching mechanism on the basis of the quenching of HSA by the complexes (1–4). However, modifications in the secondary structure of HSA by complexes (1–4) inferred via CD measurements which revealed the enhancement of α-helicity (67.47% to 69.20%) with the preference order of 1 > 2 > 3 > 4. Furthermore, in-vitro antibacterial study against different bacteria and antioxidant activities against DPPHradical dot and superoxide radical (O2−radical dot) at variable concentrations outspread discernible bio-potencies of the metal complexes as compared to free ligand scaffolds due to the chelation effect.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Ligand binding, Biochemistry