Evaluation of DNA Binding, Radicals Scavenging and Antimicrobial Studies of Newly Synthesized N-Substituted Naphthalimides: Spectroscopic and Molecular Docking Investigations.

ABSTRACT

In this study, we investigated a new series of naphthalimide based Schiff base compounds as potential DNA binding, antioxidant and antimicrobial agents. The structural characterization of synthesized compounds was carried out with the aid of elemental analysis and spectroscopic techniques (UV-vis., IR, (1)H and (13)C NMR). The DNA binding properties of target compounds against Ct-DNA (calf thymus) have been investigated in detail by numerous biophysical techniques (UV-vis, fluorescence, ethidium bromide displacement assay, Time resolved fluorescence, viscosity, cyclic voltammetry and circular dichorism) and the evidences have suggested that the test compounds could interact with DNA via intercalative binding. The extent of DNA binding (Kb) of these compounds follow the order of 3b (3.33 × 10(4) M(-1)) > 3a (2.25 × 10(4) M(-1)) > 3c (2 × 10(4) M(-1)), suggesting that compound 3b binds more strongly to Ct- DNA than the compounds 3a and 3c. Molecular docking results further support intercalative binding of test compounds with DNA. The binding energies of docked compounds (3a-3c) were found to be -8.20 to -8.69 kcal/ mol, suggesting greater binding affinity to Ct-DNA. The synthesized compounds displayed potential antimicrobial activities against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Salmonella typhimurium. Compound 3c has emerged as most active against all the four tested bacterial strains with MIC value in the range of 0.031-0.062 mg/mL. In the mutagenicity studies, all the test compounds were found to be non-mutagenic both in the presence and absence of metabolic activation. Furthermore, the antioxidant activity experiments show that these compounds exhibited potential scavenging activities against DPPH and H2O2 radicals.