In Vitro Study of the Damaging Effects of the Fungicide Dithianon on DNA Structure by Spectroscopic Techniques

The common broad-spectrum protectant fungicide known as Dithianon is utilized in agriculture to manage pests; however, it could pose risks to human health. Dithianon may be associated with health problems due to its affinity for DNA. The interaction between Dithianon and calf thymus DNA (CT-DNA) was examined using UV-Vis absorption, fluorescence spectroscopy, and viscosity measurements with Neutral Red (NR) dye as a spectral probe in a physiological buffer. Dithianon, intercalated in DNA (K [DNA-Dithianon] = 2.3 × 10⁵ M^-1), causes the displacement of the NR dye from the NR-DNA complex. The binding constants (K_f), the number of binding sites (n ≈ 1), and thermodynamic parameters of the interaction of DNA-Dithianon were determined using the fluorescence quenching method at various temperatures. Dithianon's ability to intercalate in DNA base pairs was further supported by the variations in CT-DNA base stacking observed in circular dichroic spectrum measurements and the rise in viscosity of the CT-DNA solution. The interaction energy between Dithianon and the DNA was primarily due to hydrophobic Van der Waals interactions. This study offers a comprehensive understanding of how dithianon interacts with CT-DNA, providing insights into the toxic effects of the fungicide.