Exploring the Noncovalent Interactions of the Dinuclear Cu(II) Schiff Base Complex with Bovine Serum Albumin and Cell Viability against the SiHa Cancer Cell Line

Abstract

In the present study, a dinuclear bis­(μ-acetate) dicopper­(II) complex [Cu2L2(μ1.1-CH3COO–)2] has been synthesized from a tridentate NNO Schiff Base ligand L (L = 2,4-dibromo-6-((3-(methylamino)­propylimino)­methyl)­phenol) and characterized by elemental, ultraviolet–visible (UV–vis), Fourier transform infrared (FTIR), 1H NMR, and electrospray ionization-mass spectrometry (ESI-MS) spectroscopic studies. The single-crystal X-ray structure, different noncovalent interactions, Hirshfeld surface analysis, and density functional theory (DFT) studies of the dinuclear complex were determined by crystallographic computational studies. The structural study exposed that the complex consists of the penta-coordinated double μ1.1-acetato-bridged dinuclear units of Cu­(II), and it is a centrosymmetric dimer in which the center of inversion lies at the midpoint of two Cu­(II) ions. Hirshfeld surface and DFT studies pointed out the probable potentiality of the crystal in prospective binding with the protein. This was experimentally verified by carrying out the binding interaction studies against bovine serum albumin (BSA) protein using various spectroscopic methods. It was observed that the copper­(II) complex could strongly bind to BSA and could quench the intrinsic fluorescence of BSA. Further, the studied complex was appraised for cell viability studies against SiHa cancer cells. It is observed that cell viability increases with time, demonstrating the biocompatible nature of the complex.

Biophysical insights into the binding capability of Cu(II) schiff base complex with BSA protein and cytotoxicity studies against SiHa

“…Furthermore, we have investigated the conformation of the protein upon the said interaction by circular dichroism (CD) spectroscopy. BSA shows helical nature in the CD spectra ( Figure 6 ) with two negative ellipticity bands at 222 nm and 208 nm corresponding to n → π∗ and π → π∗ transitions, respectively [ 40 ]. It is important to note that CD spectra of the protein in presence of complex below 220 nm could not be monitored, as the complex shows strong absorption below this wavelength range and also due to observing high voltage values for the instrumental limitation within the mentioned wavelength range [ 40 ].…”

“…BSA shows helical nature in the CD spectra ( Figure 6 ) with two negative ellipticity bands at 222 nm and 208 nm corresponding to n → π∗ and π → π∗ transitions, respectively [ 40 ]. It is important to note that CD spectra of the protein in presence of complex below 220 nm could not be monitored, as the complex shows strong absorption below this wavelength range and also due to observing high voltage values for the instrumental limitation within the mentioned wavelength range [ 40 ].

Figure 6 CD spectra represent the helical nature of BSA in the absence of complex (Black) and in the presence of 16 μM (red) and 32 μM (blue) of complex.

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Unveiling the catecholase activities and DNA binding interaction of mono-, di-, and polymeric Cu(ii) complexes derived from heterogeneous Schiff base ligands

“…The syntheses, characterization and crystal structure determination of the three complexes along with three heterogeneous Schiff base ligands L1, N-((6-methoxypyridin-2-yl)methylene)-(piperidin-2-yl)methane amine, L2, 2,4-dibromo-6-((3-(methylamino)propylimino)methyl)phenol and L3, 1-((3-(methylamino) propylimino)methyl)naphthalene-2-ol were discussed in our previous publications. 22,23 The crystal structure of complex 1 shows a square pyramidal geometry, whereas the structure of complex 2 shows that the complex consists of penta coordinated double m 1.1 -acetato bridged dinuclear units of Cu(II) and is a centro symmetric dimer in which the centre of inversion lies at the midpoint of two Cu(II) ions (Fig. S7 in the ESI †).…”

“…The syntheses of the three complexes were performed using a method reported by Samanta et al 22,23 Characterizations by single crystal X-ray diffraction studies and several other physicochemical techniques such as FT-IR, UV-vis, ESI-MS and NMR to establish the structures of the complexes were also performed by Samanta et al 22,23 (Scheme 1). All the structures of the complexes were established using single crystal X-ray crystallography and these structures are given in Fig.…”

Combined theoretical and experimental insights on DNA and BSA binding interactions of Cu(ii) and Ni(ii) complexes along with the DPPH method of antioxidant assay and cytotoxicity studies

“…S8b †). Upon excitation at 295 nm Tryptophan (W) of BSA elicits uorescence emission centered at 350 nm, [43][44][45][46][47] which shows reduction in its intensity (Fig. 5a and b) with successive addition of both the complexes as a result of quenching.…”