Preliminary Assessment of p-Anisidinium-Based Ionic Solids as Potential DNA Staining Agents: DFT and Molecular...

This work involved the preparation and characterization of a variety of p-anisidinium-based ionic solids (ISs) exhibiting significant DNA-staining capabilities, as guided and evidenced by their observed chromogenic behavior in ethanol under UV-Vis absorption. The obtained structural and functional group elucidation results verified the successful preparation of the ISs (¹H and ¹³C-NMR, and FTIR), the significant role played by different anions on their overall colour compared to the pristine material was validated, and this was attributed to the aniline chromophore moiety and electronic interaction between the cation and anion. The UV-Vis absorption spectra illustrated three characteristic bands attributed to π→π*, n→π*, and intermolecular anion-cation charge-transfer-transition (CTT) commonly observed for p-anisidinium-based compound. Gel electrophoresis analysis was conducted to examine the potential of the ISs as novel alternatives that can be used either as loading or fluorescent DNA staining dyes. Among the examined, [p-Anis]⁺[NO₂]^- was illustrated as a potent alternative loading and fluorescent DNA-staining dye. This observation was further validated with DFT simulation using b3lyp/6-311 + + g(d, p) method, and gave energy gap 3.40 eV, suggesting good chemical reactivity and moderate electronic conductivity, with global electrophilicity index value of 3.41 eV suggesting low stabilization energy and high susceptibility to charge transfer. The obtained ADME parameters suggest that this compound is soluble in water, have good drug likeness, supporting its DNS binding affinity, and a potential orally active drug since it obeys both Lipinski and Verber rules. The binding energies from the molecular docking simulations are - 6.9 and - 4.9 kcal/mol for ciprofloxacin and [p-Anis]⁺[NO₂]^-, respectively against Escherichia coli; and - 5.7 and - 5.9 kcal/mol for metronidazole and [p-Anis]⁺[NO₂]^-, respectively against Clostridium difficile. Key residues Met404 and Ala429 are common in both pairs for E. coli while Arg272 and Asp285 in both pairs C. difficile.