Synthesis, X-ray structures and biological evaluation of novel α-aminophosphonate derivatives as anti-inflammatory and antioxidant agents: an integrated in vitro and in silico study

Abstract

In the field of medicinal chemistry, the design of small molecules is acknowledged as an effective strategy. This study may contribute to the global fight against inflammatory diseases by focusing on the synthesis of novel α-aminophosphonate derivatives incorporating para-aminobenzoic acid (PABA) and benzocaine moieties and evaluating their anti-inflammatory and antioxidant activities. Compounds 1a–1i, 2a–2g and 3a–3f were efficiently prepared via a one-pot Kabachnik–Fields reaction in moderate to high yields. Structural characterization was achieved using spectroscopic techniques and single-crystal X-ray diffraction. Antioxidant activity, assessed by ABTS (<0.1 mM) and phenanthroline (<0.5 mM) assays, revealed that several derivatives exhibited significant radical scavenging and reducing power, particularly those bearing electron-donating groups. In vitro anti-inflammatory evaluation using the bovine serum albumin denaturation assay identified compounds 1f, 3f, 2g and 1i as the most active derivatives, with compound 1f (97.63% ± 0.99%) showing activity comparable to that of diclofenac (98.70% ± 0.15%). Toxicity tests on Tenebrio molitor larvae indicated low toxicity at effective concentrations. Compound 1f was only moderately toxic (50% of mortality rate) at the highest concentration tested (4 mM), and no mortality was observed at lower doses. DFT calculations provided insights into the electronic and physicochemical properties of the synthesized compounds. Molecular docking and molecular dynamics simulations generated hypotheses regarding their possible interactions with the COX-2 binding site, while ADMET analyses predicted the potentially acceptable pharmacokinetic profiles of several derivatives. However, these computational findings do not demonstrate direct COX-2 inhibition, target engagement, or selectivity. When considered alongside the preliminary experimental results, they support prioritizing compound 1f for further experimental evaluation.