Interaction with biomacromolecules and antiproliferative activities of Mn(II), Ni(II), Zn(II) complexes of demethylcantharate and 2,2′-bipyridine

•Three new complexes of demethylcantharate and 2,2-bipyridine were synthesized.•Their structures were determined by X-ray diffraction.•The complexes bound DNA moderately via partial intercalation modes.•They have intense interaction with BSA through static quenching.•The Zn(II) complex has strongest activities against the two tested cancer cell lines.

Three new transition metal complexes [Mn2(DCA)2(bipy)2]·5H2O (1), [M2(DCA)2(bipy)2(H2O)]·10H2O(M = Ni(II)(2);Zn(II)(3)), (DCA = demethylcantharate, 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, C8H8O5) were synthesized and characterized by elemental analysis, molar conductance, infrared spectra and X-ray diffraction techniques. Each metal ion was six-coordinated in complexes. Complex 1 has a Mn2O2 center. Complexes 2 and 3 have asymmetric binuclear structure. Great amount of intermolecular hydrogen–bonding and π–π* stacking interactions were formed in these complex structures. The DNA-binding properties of complexes were investigated by electronic absorption spectra and viscosity measurements. The DNA binding constants Kb/(L mol−1) were 1.71 × 104 (1), 2.62 × 104 (2) and 1.59 × 104 (3) at 298 K. The complexes could quench the intrinsic fluorescence of bovine serum albumin (BSA) strongly through static quenching. The protein binding constants Ka/(L mol−1) were 7.27 × 104 (1), 4.55 × 104 (2) and 7.87 × 104 L mol−1 (3) and binding site was one. The complexes bind more tightly with DNA and BSA than with ligands. Complexes 1 and 3 had stronger inhibition ratios than Na2(DCA) against human hepatoma cells (SMMC-7721) lines and human gastric cancer cells (MGC80-3) lines in vitro. Complex 3 showed the strongest antiproliferative activity against SMMC-7721 (IC50 = 29.46 ± 2.12 μmol L−1) and MGC80-3 (IC50 = 27.02 ± 2.38 μmol L−1), which shows potential in anti-cancer drug development.

Graphical abstractThree new Mn(II), Ni(II), Zn(II) complexes of demethylcantharate and 2,2-bipyridine were designed and synthesized. 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 in vitro.Figure optionsDownload full-size imageDownload as PowerPoint slide