DNA interaction and anticancer evaluation of new palladium(II), platinum(II) and silver(I) complexes based on (Δ)- and (Λ)-1,2-bis-(1H-benzimidazol-2-yl)-1,2-ethanediol enantiomers

The synthesis of some new palladium(II), platinum(II) and silver(I) complexes based on (Delta)- and (Lambda)-1,2-bis-(1H-benzimidazol-2-yl)-1,2-ethanediol (Delta-H(2)bie and Lambda-H(2)bie) enantiomers in the absence and presence of the N,N-chelates 2,2'-bipyridyl and 9,10-phenanthroline, and triphenylphosphine is reported. The molecular structures of the new complexes are discussed on the basis of their IR, Raman, UV-Vis, NMR ((1)Eta, C-13 and (31)Rho) and mass spectra, elemental analyses, molar conductivities and TGA properties. Both Delta-H(2)bie and Lambda-H(2)bie coordinate to the metal ions in a neutral bidentate manner through the azome-thine-N and protonated hydroxy-O atoms, while in basic media, Delta-Hbie(-) and Lambda-Hbie(-) are bound to the metal ions through the azomethine-N and deprotonated-O atoms as mono-negative bidentate chelating ligands. The in vitro anticancer activity of the complexes has been evaluated against the human breast cancer (MDA-MB231) and ovarian cancer (OVCAR-8) cell lines. The Delta-H(2)bie complexes are more active against the studied cell lines. The IC50 values for cell growth proliferation of [Ag(PPh3)(Lambda - Eta(2)bie)]CIO4 and [Ag(PPh3)(Lambda-Hbie))are 0.443 and 1.277 mu M, and 0.427 and 1.437 mu M for the MDAMB231 and OVCAR-8 cell lines, respectively. The corresponding IC50 values for cisplatin were 3.20 (MDA-MB231) and 2.28 (OVCAR-8) mu M. The DNA-binding properties of some of the complexes have been studied using circular dichroism (CD) spectroscopy. The results indicate that the complexes may have intercalative CT-DNA binding capabilities. The intercalation of the Delta-enantiomers appears to be greater than is that for the Lambda-enantiomers. Insertion of the complexes into adjacent base pairs prevents neighboring base pairs from close stacking. (C) 2018 Published by Elsevier Ltd.