New sulfonamide complexes with essential metal ions [Cu (II), Co (II), Ni (II) and Zn (II)]. Effect of the geometry and the metal ion on DNA binding and nuclease activity. BSA protein interaction

• Published in: Journal of inorganic biochemistry 2020-01, Vol.202, p.110823-110823, Article 110823
• Main Authors: Tŏpala, Tamara, Pascual–Álvarez, Alejandro, Moldes–Tolosa, M. Ángeles, Bodoki, Andreea, Castiñeiras, Alfonso, Torres, Javier, del Pozo, Carlos, Borrás, Joaquín, Alzuet–Piña, Gloria
• Format: Article
• Language: English
• Subjects: BSA interaction; DNA binding; Essential metal ions; Nuclease activity; Photonuclease activity; Sulfonamide complexes
• ISSN: 0162-0134; 1873-3344
• DOI: 10.1016/j.jinorgbio.2019.110823

Mixed divalent Cu, Co, Ni and Zn complexes containing the new sulfonamide ligand N–(2–(pyridin–2–yl)ethyl)quinoline–8–sulfonamide (HQSEP) were prepared and characterized by physico-chemical techniques. The tetracoordinate [Cu(QSEP)X] [X = Br (1), Cl (2)] compounds present a seesaw geometry (τ4 = 0.56 (1) and 0.50 (2)). The Cu(II) in the [Cu(QSEP)(NO3)(MeOH)] (3) complex is five coordinate with a slightly distorted SP geometry (τ = 0.11). The [M(QSEP)(benz)] [M = Cu(II) (4), Ni(II) (5), Co(II) (6) and Zn(II) (7); benz = benzoate] compounds are configurationally isotypic. The coordination geometries of the M(II) ions can be best described as distorted SP (τ = 0.29, 0.15, 0.34 and 0.18 for 4, 5, 6 and 7, respectively). The interaction of the compounds with CT–DNA was studied by different techniques. Notably, these studies indicated that the tetracoordinate complexes (1 and 2) present higher DNA affinity than pentacoordinate compounds (3–7). In line with the Irving–Williams order of stability, 5 presented higher propensity for DNA binding than 6. Interestingly, the cleavage activity of 1–4 in the presence of ascorbate/H2O2 follows the same trend as that found for DNA binding affinity, being the tetracoordinate 1 and 2 more effective as nucleases than the five coordinate 3 and 4. Also, the DNA cleavage reaction mechanism was investigated. DNA cleavage experiments upon irradiation indicated the important role of the aromatic nature of the coligand in the photocleavage activity of 1–4. Finally, the interaction of the compounds with bovine serum albumin (BSA) was studied and the binding constants were calculated. Mixed divalent Cu, Co, Ni and Zn complexes (1–7) with a new sulfonamide ligand (HQSEP) were prepared and characterized. Their propensity for DNA binding and DNA cleavage activity with ascorbate/H2O2 and upon irradiation was studied. Moreover, the binding of the complexes to bovine serum albumin (BSA) was tested. [Display omitted] •Seven sulfonamide complexes have been synthesized and structurally characterized.•Tetracoordinate 1 and 2 present higher affinity for DNA than pentacoordinate 3–7.•The different DNA affinity of 1 and 2 is related to their mode of interaction.•The DNA cleavage activity follows the same trend observed for DNA binding affinity.•The aromatic nature of the coligand determines the photonuclease activity of 1–4.