Synthesis, characterization and in vitro DNA binding of chromone Schiff base organotin(IV) complexes

• New organotin(IV) Schiff base complexes of ethanolamine and 3-formylchromone, 1–3.
• The complexes 1–3 bind to DNA in electrostatic interaction via phosphate backbone.
• 5′-GMP interaction studies were carried out to evaluate site-specific recognition.
• Phenyl derivatives (complex 2 and 3) were found to be good antimicrobial agents.
• Molecular docking results corroborated well with the spectroscopic results.

New chromone Schiff base organotin(IV) complexes {dimethyltin dichloride, diphenyltin dichloride and triphenyltin chloride} 1–3 were synthesized and thoroughly characterized by various spectroscopic methods (FT-IR, NMR and ESI-MS), elemental analysis and molar conductance values. The in vitro DNA binding profile of complexes 1–3 was carried out by absorption, fluorescence spectroscopy and viscosity measurements. The corroborative results of DNA binding studies revealed that the complexes 1–3 exhibit electrostatic mode of binding preferably via oxygen of sugar-phosphate backbone of DNA helix. The extent of DNA binding was determined quantitatively by Kb, K and Ksv values which demonstrated greater DNA binding propensity of 2 as compared to 1 and 3. In order to obtain further evidence and to determine the interaction mode of the metal ion to the specific target site at the molecular level of complexes 1–3, interaction with 5′-GMP involving UV–vis, 1H and 31P NMR studies were carried out which validated their preferential phosphate binding affinity. Additionally, the molecular docking studies of complex 2 was carried out with B-DNA (PDB ID: 1BNA) which also revealed an electrostatic interaction mode via outside edge stacking with the oxygen atom of the phosphate backbone of DNA. Further, antibacterial and antifungal activity of organotin(IV) complexes 1–3 was also evaluated.

Interaction and antimicrobial studies of complex 2. Figure optionsDownload as PowerPoint slide