化学
人血清白蛋白
圆二色性
氢键
结合常数
猝灭(荧光)
荧光
疏水效应
荧光光谱法
结晶学
立体化学
结合位点
分子
色谱法
有机化学
生物化学
量子力学
物理
作者
Otávio Augusto Chaves,Cosme H.C. dos Santos Oliveira,Romulo Correia Ferreira,Darí Cesarín-Sobrinho,Antônio Eduardo da Hora Machado,José Carlos Netto‐Ferreira
标识
DOI:10.1016/j.chphi.2023.100411
摘要
Spectroscopic studies were carried out for the interaction of the bioactive compounds 2,3-dimethoxyxanthone (1) and 3,4-dimethoxyxanthone (2) with human serum albumin (HSA). The UV absorption, steady-state, and time-resolved fluorescence spectroscopy studies showed that 1 and 2 interact with HSA through a ground-state association. The decrease in the Stern-Volmer constant (KSV) values with increasing temperature, and the bimolecular quenching rate constant (kq) values in the order of 1012 M−1s−1 indicated a static fluorescence quenching mechanism, corroborating with time-resolved fluorescence decays. The association constant (Ka) values in the order of 104 M−1 indicated a moderate interaction between these xanthones and HSA. Circular dichroism experiments showed weak perturbation on the secondary structure of albumin after the interaction with 1 and 2. Thermodynamic parameters suggested that the binding is entropically (for HSA:1, ΔS° 0.012±0.003 and for HSA:2 0.008±0.002 J/molK) and enthalpically (for HSA:1, ΔH° -24.0 ± 0.99 and for HSA:2 -25.6 ± 0.67 kJ/mol) controlled, with a Gibbs free energy change (ΔG°) close to -28.0 kJ/mol in both cases. Competitive drug-displacement and molecular docking results showed that 1 and 2 could interact not only with subdomain IIA, where Trp-214 residue can be found, but also with subdomains IIIA and IB. Hydrogen bonding, electrostatic, and hydrophobic interactions were detected as the main binding forces to stabilize the association HSA:1 and HSA:2. Overall, the dimethoxyxanthones have similar binding affinity compared with highly oxygenated xanthones, e.g., mangiferin, gentiacaulein, and norswertianin.
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