In Vitro and Computational Studies of Indoleninyl-Pyrimido[1,2-b]Indazoles as DNA Binding Agents

A series of indoleninyl-pyrimido[1,2-b]indazoles, including the parent compound 1 and its derivatives (2–4) with different substituents were previously synthesized. However, their precise mode of DNA interactions is still largely unexplored. DNA binding studies revealed that only compound 3 exhibited significant hyperchromism with a binding constant, K_b of 5 × 10⁶ M^− 1, indicating that it strongly binds to the DNA minor groove. As demonstrated from DNA denaturation studies, ionic strength studies, and molecular docking calculations, the minor groove binding ability of 3 was confirmed, with electrostatic and hydrophobic interactions involved in the formation of the DNA adduct. In summary, these preliminary findings from both computational and experimental studies suggested that 3 remains promising for further development as a cytotoxic agent targeting DNA.