Exploring the interaction of Valsartan and Valsartan-Zn(ll) complex with DNA by spectroscopic and in silico methods.

Belonging to the Sartan family, antihypertensive drug - Valsartan (Val) had been found to possess antioxidant properties. Also, the zinc complex of Valsartan (VZn) has been recently recognized as inducing agents of the reductive stress effects thus possessing anticancer activity. Hence, in this work an attempt has been made to understand the interaction of Val and VZn with DNA using spectroscopic and in silico methods as DNA has been identified as the target for many anticancer drugs. VZn has been prepared in 2:1 M ratio and characterised by absorbance, FTIR, HRMS, NMR and Job's continuous variation method. VZn has been tested against human lungs cancer cell line which exhibited good anticancer activity (IC50 = 89 µg/mL). Interaction of Val and VZn with ct-DNA under physiological conditions has been studied by spectroscopic techniques such as fluorescence, absorbance, FTIR, circular dichroism (CD) and in silico methods. Fluorescence quenching, DNA melting and viscometric studies confirmed that both ligand and complex bind to the grooves of the ct-DNA. The experimental results have revealed that VZn strongly bind with DNA compared to Val. Docking study suggested that, Val binds at major groove while VZn binds to both minor and major grooves of B-DNA.

Comprehensive analysis of the atenolol - DNA complex by viscometric, molecular docking and spectroscopic techniques.

This paper discusses multi-spectroscopic and molecular docking analysis of the interaction between atenolol (ATN) and deoxyribose nucleic acid (DNA) using alizarin (ALZ) as a spectroscopic probe. ATN is a ß1 -receptor antagonist belonging to the ß-blocker class of molecules. Experimental findings that were based on different spectroscopic analysis, melting studies, viscometric analysis, 1 H nuclear magnetic resonance and circular dichroism studies revealed the presence of a grove-binding mode. The effect of ionic strength was also studied, and observations suggested that electrostatic interaction also played a minor role during interaction. Molecular docking analysis suggested that the dominant force for the grove-binding phenomenon was hydrogen bonding between the 24-H residue of ATN and O of the 10-G residue, and the 40-H residue of ATN and N of the 17-A base residue. Competitive binding study of the ALZ-DNA complex with ATN showed that, despite an increase in the amount of ATN in the ALZ-DNA complex, the overall absorbance remained unchanged. The decrease in fluorescence in the ALZ-DNA system may be due to new non-fluorescent ATN-DNA-ALZ complex formation.