Investigating binding of insecticide buprofezin to DNA by experimental and metadynamics simulation studies.

Buprofezin () is an insecticide which belongs to the thiadiazine structural family and known to damage DNA in mice. Though its toxic effect on human is not known clearly, understanding the mechanism of interaction of with DNA can prove useful when required. Multi-spectroscopic experiments such as UV-Vis, fluorescence, circular dichroism (CD) and H NMR coupled with viscosity measurements, urea effect and voltametric studies were performed to ascertain the mode of binding of with calf thymus DNA (CT-DNA). Analysis of UV-Vis and fluorescence spectra indicated the formation of a complex between and CT-DNA. Other experiments such as competitive binding assays with ethidium bromide (EB) and Hoechst 33258, viscosity measurements, effect of urea, CD, voltammetric studies and H NMR spectral analysis suggested that intercalates into the base pairs of CT-DNA. All these results revealed that the binding mode of with CT-DNA should be intercalation and the binding constant is in the order of 10 M. The ΔH < 0 and ΔS < 0 suggested that H-bonding or van der Waals force was the main binding force between and CT-DNA. The proposed mode of binding of with CT-DNA has been visualized using molecular docking and metadynamics simulation studies, which showed that the phenyl ring of binds to CT-DNA via π-π stacking interaction in addition to H-bond formation.Communicated by Ramaswamy H. Sarma.