Crystal structures, interactions with biomacromolecules and anticancer activities of Mn(II), Ni(II), Cu(II) complexes of demethylcantharate and 2-aminopyridine.

Three novel transition metal complexes (Hapy)(2)[M(DCA)(2)]·6H(2)O (M = Mn(II) (1), Ni(II) (2), Cu(II) (3); DCA = demethylcantharate, 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylate, C(8)H(8)O(5); Hapy = 2-aminopyridine acid, C(5)H(7)N(2)) were synthesized and characterized by elemental analysis, infrared spectra, thermogravimetric analysis and X-ray diffraction. DNA binding properties of the complexes were investigated by electronic absorption spectra, fluorescence spectra and viscosity measurements. Results indicated the complexes could bind to DNA through partial intercalation mode with binding constants K ( b )/(L·mol(-1)) of 1.91 × 10(4) (1), 5.13 × 10(4) (2) and 1.12 × 10(5) (3) at 298 K. Meanwhile, the interactions of the complexes with BSA were also studied by fluorescence spectra. The results suggested that the complexes could quench the fluorescence of BSA through static quenching with the binding constants K ( A )/(L·mol(-1)) of 1.44 × 10(6) (1), 1.14 × 10(7) (2) and 2.98 × 10(4) (3). And the main contribution was tryptophan residues of BSA. The antiproliferative activity test revealed that complexes showed more intense inhibition ratios against human hepatoma cells lines and human gastric cancer cells lines in vitro. Copper(II) complex (3) possesses the strongest inhibition ratio against human hepatoma cells.