Exploring the binding mechanism of 5-hydroxy-3',4',7-trimethoxyflavone with bovine serum albumin: Spectroscopic and computational approach

The current study was carried out to investigate the binding mechanism of a potential flavonoid compound 5-hydroxy-3',4',7-trimethoxyflavone (HTMF) with bovine serum albumin (BSA) using ultraviolet-visible, fluorescence, circular dichroism (CD) spectral measurements along with molecular docking and molecular dynamics (MD) simulation. It was confirmed from fluorescence spectra that the intrinsic fluorescence of BSA was robustly quenched by HTMF through a static quenching mechanism. The number of binding sites (n) for HTMF binding on BSA was found to be about one. The thermodynamic parameters estimated from the van't Hoff plot specified that hydrophobic force was the predominant force in the HTMF-BSA complex and there also exist hydrogen bonds and electrostatic interactions. The effect of HTMF on the BSA conformation examined using CD studies revealed that there is a decrease in the helical content of BSA upon HTMF interaction. The results of molecular docking study shed light on the binding mode which exposed that HTMF bind within the hydrophobic pocket of the subdomain IIIA of BSA. The stability of HTMF-BSA complex with respect to free protein was analyzed from the molecular dynamic studies. The electronic structure analysis of HTMF was achieved by using density functional theory (DFT) calculations at B3LYP/6-31G** level to support its antioxidant role. The results of computational analysis are in good consistence with the experimental data and the present findings suggested that HTMF exhibits a good binding propensity to BSA protein which will be helpful for the drug design.

6-Chloro-2-(4-meth-oxy-phen-yl)-4-phenyl-quinoline

In the title compound, C₂₂H₁₆ClNO, the quinoline ring system makes dihedral angles of 56.30 (6) and 7.93 (6)°, respectively, with the adjacent phenyl and benzene rings. The dihedral angle between these phenyl and benzene rings is 56.97 (8)°. In the crystal, weak C—H⋯π and π–π [centroid–centroid distances of 3.7699 (9) and 3.8390 (9) Å] inter­actions link the mol­ecules into a layer parallel to the ab plane.

Di-μ-hydroxido-κ(4) O:O-di-μ-perchlorato-κ(4) O:O'-bis-[(2,2'-bi-pyridine-κ(2) N,N')copper(II)]

In the title binuclear copper(II) complex, [Cu₂(ClO₄)₂(OH)₂(C₁₀H₈N₂)₂], the Cu^II ion is coordinated in the form of a Jahn–Teller distorted octahedron by two bi­pyridine N atoms, two perchlorate O atoms and two hydroxide O atoms, and displays a distorted octa­hedral geometry. The mol­ecule belongs to the symmetry point group C_2h. The Cu^II ion is located on a twofold rotation axis and the hydroxide and perchlorate ligands are located on a mirror plane. Within the dinuclear mol­ecule, the Cu⋯Cu separation is 2.8614 (7) Å. The crystal structure exhibits O—H⋯O, C—H⋯O and π–π [centroid–centroid distance = 3.5374 (13) Å] inter­actions.

1,2-Bis(2-hy-droxy-5-methyl-benzyl-idene)hydrazine

The mol-ecular structure of the title compound, C16H16N2O2, is stabilized by intra-molecular O-H⋯N hydrogen bonds with S(6) graph-set motifs, so that the mol-ecule is almost planar, with a C=N-N=C torsion angle of -179.7 (2)° and a dihedral angle of 1.82 (12)° between the aromatic rings. In the crystal, weak C-H⋯π inter-actions lead to the formation of a three-dimensional network.

2-Hydroxy-3-methoxymethyl-5-methylbenzaldehyde

In the title mol­ecule, C₁₀H₁₂O₃, all non-H atoms lie in a common plane (r.m.s deviation = 0.010 Å). The mol­ecular conformation is stabilized by an intra­molecular O—H⋯O hydrogen bond.