Two novel cadmium(II) complexes with demethylcantharate and polypyridyl: Crystal structure, interactions with DNA and bovine serum albumin

Two novel mixed-ligand complexes [Cd2(DCA)2(bipy)2(H2O)2] (1) and [Cd2(DCA)2(phen)2]·4H2O (2) (DCA = demethylcantharate, 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, C8H8O5; bipy = 2,2′-bipyridine, C10H8N2; phen = phenanthroline, C12H8N2) were synthesized and characterized by elemental analysis, infrared spectra, thermogravimetric analysis and X-ray diffraction. The complexes crystallized in the triclinic crystal system with P1¯ space group. The complex was binuclear molecule. In complex 1, Cd(II) ion was seven-coordinated by two nitrogen atoms from bipy, four oxygen atoms of carboxyl groups from DCA and one water molecule. In complex 2, each Cd(II) ion was six-coordinated by two nitrogen atoms from phen, one ether oxygen atom and three oxygen atoms of carboxyl groups from DCA. DNA binding properties of the complexes were investigated by electronic absorption spectra, fluorescence spectra and viscosity measurements. Results indicated that the complexes bound to DNA via partial intercalation mode. The values of binding constants Kb/(M−1) were 1.03 × 104 (1) and 5.26 × 104 (2) at 298 K. Meanwhile, the complexes could quench the fluorescence of bovine serum albumin (BSA) through static quenching with the binding constants KA/(M−1) of 2.87 × 105 (1) and 3.87 × 105 (2) and the binding site of 0.98 (1) and 0.97 (2). In addition, complex 2 had stronger inhibition ratios than Na2(DCA) against human hepatoma cells (SMMC7721) lines and human gastric cancer cells (MGC80-3) lines in vitro. The IC50 values of complex 2 against the two tested cells were 25.54 ± 6.66 and 19.14 ± 1.05 μM, respectively.

Two novel cadmium(II) complexes of demethylcantharate and polypyridyl were designed and synthesized, the structures were determined by X-ray diffraction. The interactions of complexes with DNA and bovine serum albumin (BSA) were studied. The antiproliferative activities against human hepatoma cells (SMMC-7721) and human gastric cancer cells (MGC80-3) were tested with MTT assay in vitro.Figure optionsDownload as PowerPoint slideHighlights
► [Cd2(DCA)2(bipy)2(H2O)2] and [Cd2(DCA)2(phen)2]·4H2O were synthesized and characterized.
► The complexes bound DNA strongly via partial intercalation modes.
► They have intense interaction with bovine serum albumin through static quenching.
► Complex 2 has strong activities against human hepatoma and gastric carcinoma cell lines in vitro.