In-vitro investigation of biophysical interactions between Ag(I) complexes of bis (methyl)(thia/selena) salen and ct-DNA via multi-spectroscopic, physicochemical and molecular docking methods along with cytotoxicity study.

Four Ag(I) complexes; 1.PF6 , 2.PF6 , 1.ClO4 and 2.ClO4 of bis (methyl)thia salen (1) and bis (methyl)selena salen (2) with two different counter anions (PF6- and ClO4- ) have been investigated for DNA binding properties. In vitro interactional association between the Ag(I) complexes and ct-DNA has been examined by performing the spectroscopic titrations on absorption spectrophotometer and fluorescence spectrophotometer. Competitive binding study has also been done by a fluorescence spectrophotometer using ethidium bromide as a classical intercalator. The spectroscopic methods revealed a major groove. Viscometry and Agarose gel electrophoresis experiments have also been performed as physicochemical methods to confirm the binding of complex molecules with DNA. Molecular docking analysis has been executed to get the theoretical insight into the mode of binding. The docking study demonstrated the major groove binding of all four complexes to the DNA with electrostatic metal-phosphate interactions (between the metal and DNA's backbone) and hydrophobic interactions. Cytotoxicity of the complexes has been studied on the Human Fibroblast foreskin (HFF) cell line. The cytotoxicity results showed positive gesture for moving ahead in the next level of screening; the values were above 10 μM appreciated for the normal cell lines.