Spectroscopic, electrochemical DNA binding and in vivo anti-inflammatory studies on newly synthesized Schiff bases of 4-aminophenazone

•4-Aminophenazone (Ap-1) and its Schiff bases, Ap-2, Ap-3, Ap-4 interact with DNA via intercalation.•All compounds showed good DNA binding as investigated by spectroscopic and voltammetric studies.•Kb, n, ΔG calculated from all techniques were well concord.•Ap-4 revealed its relatively stronger binding at stomach pH.•Ap-4 exhibited greater percentage of edema inhibition than other Schiff bases.

4-Aminophenazone (Ap-1) Schiff bases i.e., 4-{(3,4,5-trimethoxybenzylidine) amino}phenazone (Ap-2), 4-{(2-chlorobenzylidine) amino}phenazone (Ap-3) and 4-{(4-chlorobenzylidine)amino} phenazone (Ap-4) were synthesized and characterized by different spectroscopic techniques. Interaction of these compounds with ds.DNA was investigated through UV–Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry at stomach (4.7) and blood (7.4) pH under 37 °C (human body temperature). Instrumental findings were further quantified both kinetically and thermodynamically. Results obtained through these techniques inferred intercalative mode of binding of all the compounds with DNA. The binding constant data, “Kb”, and free energy change, ΔG, indicated comparatively greater binding affinity and more spontaneity of binding of compounds with DNA at stomach pH (4.7), respectively. However, among these compounds, Ap-4 showed comparatively greater binding at both the pH. Formation of compound-DNA complex was further confirmed through the decrease in diffusion rates after the addition of DNA. The in vivo anti-inflammatory activity of the compounds was evaluated using the carrageenan-induced hind paw edema method. The results revealed that among all the compounds, Ap-4 showed greater percentage of edema inhibition compared to standard drug.

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