Masoomeh Shaghaghi; Samaneh Rashtbari; Laleh Solouki; Somaieh Soltani; Gholamreza Dehghan
Abstract
Danofloxacin (DNF), a synthetic fluoroquinolone, is widely used as an antibacterial agent against a broad spectrum of pathogens. In the present study, the effects of DNF on the structure of bovine serum albumin (BSA) were investigated using UV-Vis absorption and fluorescence spectroscopy, and molecular ...
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Danofloxacin (DNF), a synthetic fluoroquinolone, is widely used as an antibacterial agent against a broad spectrum of pathogens. In the present study, the effects of DNF on the structure of bovine serum albumin (BSA) were investigated using UV-Vis absorption and fluorescence spectroscopy, and molecular docking methods at different temperatures. The obtained results of UV-Vis absorption studies showed that the microenvironment of the fluorophore residues does not significantly change upon interaction with DNF. Also, fluorometric studies revealed BSA-DNF complex formation and fluorescence quenching of BSA in the presence of DNF. The number of binding sites and binding constants were calculated to be ~1 and in the order of 103, respectively. According to thermodynamic parameters, van der Waals forces and hydrogen bonding play the main role in the BSA-DNF complex formation, which is a spontaneous process. The binding distance between DNF and BSA was calculated by the Förster resonance energy transfer (FRET) method. Molecular docking results were in agreement with thermodynamic and spectroscopic data and confirmed the binding mechanism of DNF to BSA.
Masoomeh Shaghaghi; Gholamreza Dehghan; Fatemeh Khajevand
Abstract
Chelation therapy has been used to remove toxic metals from the body for a long time. Flavonoids such as quercetin (QUR), a well-known protective antioxidant and free radical scavenger, can bind to metal cations and protect our bodies from toxic metals. In the current study, we used UV–Vis, 1HNMR, ...
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Chelation therapy has been used to remove toxic metals from the body for a long time. Flavonoids such as quercetin (QUR), a well-known protective antioxidant and free radical scavenger, can bind to metal cations and protect our bodies from toxic metals. In the current study, we used UV–Vis, 1HNMR, IR, and fluorescence spectroscopic techniques as well as viscosity measurements to investigate the synthesis, characterization, and interaction between Bi(III)-QUR complex and calf thymus DNA (ctDNA) in physiological buffer. The antioxidant activity of the complex was assessed utilizing DPPH and ABTS free radical scavenging, and ferric reducing potential. After chelation of the Bi(III) cation, the antioxidant potential of QUR was reduced. In the presence of ctDNA, the absorption spectrum of Bi(III)-QUR complex was raised, and the fluorescence intensity of Bi(III)-QUR complex was increased. With the addition of the Bi(III)-QUR complex, the relative viscosity of ctDNA rose. These findings indicate that the Bi(III)-QUR complex interacts with ctDNA in a groove-binding mode. The thermodynamic parameters (ΔH, ΔS, and ΔG) of the Bi(III)-QUR complex with ctDNA, as well as well as association constant, Ka, and number of binding sites (n), were assessed from the fluorescence data, indicating that the binding of Bi(III)-QUR complex to ctDNA was primarily driven by hydrophobic interactions.