Binding interaction, conformational change, and molecular docking study of N-(pyridin-2-ylmethylene)aniline derivatives and carbazole Ru(II) complexes with human serum albumins

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• 作者：Saravanan Thangavel^a ; Ramar Rajamanikandan^b ; Holger B. Friedrich^a ; ^{friedric@ukzn.ac.za" class="auth_mail" title="E-mail the corresponding author} ; Malaichamy Ilanchelian^b ; Bernard Omondi^a
• 关键词：Ru(II) complexes ; N ; N&prime ; chelated ligands ; Human serum albumins ; Circular dichroism ; Molecular docking
• 刊名：Polyhedron
• 出版年：2016
• 出版时间：9 March 2016
• 年：2016
• 卷：107
• 期：Complete
• 页码：124-135
• 全文大小：2086 K

文摘

New [RuCl₂(1,5cod)(L1)] (1), [RuCl₂(1,5cod)(L2)] (2), [RuCl₂(1,5cod)(L3)] (3), [RuCl₂(1,5cod)(L4)] (4), [RuCl₂(1,5cod)(L5)] (5) (L = (p-R-N-(pyridin-2-ylmethylene)aniline), R = H (L1), Cl (L2), OCH₃ (L3), CH₃ (L4), L5 = (9-ethyl-N-(pyridin-2-ylmethylene)9H-carbazole-3-amine and 1,5cod = η⁴-cyclooctadiene) complexes were synthesized and characterized by ¹H and ¹³C NMR, melting point analysis, elemental analysis, HR-Mass spectrometry, FT-IR and UV–Vis spectroscopy. The single crystal X-ray structures of complexes 1, 2 and 3 revealed coordination of the ligands to the Ru(II) center in a bidentate manner via the N atoms. The geometry around the Ru(II) center is pseudooctahedral with the two Cl atoms and the π-bonds of the cyclooctadiene occupying the coordination sites. Interactions of Ru(II) complexes 1–5 with human serum albumins (HSA) were investigated using UV–Vis, synchronous emission and circular dichroism spectroscopy. The results demonstrated that the Ru(II) complexes 1–5 have significantly strong interaction with HSA proteins. Complexes 1, 3 and 5 showed moderate-to-high binding constants (K_b) 1.77 × 10⁵ dm³ mol⁻¹ (1), 1.07 × 10⁵ dm³ mol⁻¹ (3) and 1.07 × 10⁵ dm³ mol⁻¹ (5) respectively. Circular dichroism (CD) studies revealed decreased α-helix content within HSA upon interaction with complexes 1–5, suggesting a conformational change of the HSA secondary structure. Also, molecular docking studies were carried out to identify the binding models of the HSA–Ru complexes and binding energy of complexes 1–5 in HSA, which further revealed the contribution of amino acid residues of HSA in Ru(II) complex binding.