Aroylthiourea derivatives of ciprofloxacin drug as DNA binder: Theoretical, spectroscopic and electrochemical studies along with cytotoxicity assessment.

Aroylthiourea derivatives of ciprofloxacin drug - [1-cyclopropyl-6-fluoro-7-(4-((4-methoxybenzoyl)carbamothioyl)piperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid] ATU-1, [1-cyclopropyl-7-(4-((2,4-dibromobenzoyl)carbamothioyl)piperazin-1-yl)-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid] ATU-2, and [1-cyclopropyl-7-(4-((3,5-dinitrobenzoyl)carbamothioyl)piperazin-1-yl)-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid] ATU-3 were synthesized, characterized and investigated for DNA binding at stomach pH (4.7) and at 37 °C. All findings by using DFT, molecular docking, spectroscopic (UV-, fluorescence; FL-), cyclic voltammetric (CV) and viscometric techniques revealed that these compounds have the potency to bind with DNA via a mixed mode of interaction. The binding affinity of ATU-1 was evaluated comparatively greater with Kb × 104/M-1 (docking; 5.55, UV-; 7.93, FL-; 5.62, CV; 6.06), ΔG/kJmol-1(docking; -27.07, UV-; -29.07, FL-; -28.18, CV; -28.38) and n (FL-; 1.20, CV; 2.72). Stern-Volmer quenching constant (Ksv) further pointed towards comparatively greater binding affinity of ATU-1 for DNA, while bimolecular quenching constant (Kq) values showed the involvement of static quenching mechanism in the compound - DNA interaction. Comparatively lesser IC50 (7.1 μM) value obtained from biological work on Huh-7 cancer cell line further confirmed the greater anticancer potential of ATU-1 than that of ATU-2&3.