Design, synthesis, and biological evaluation of a new series of amide-linked chalcone derivatives as selective COX-2 inhibitors.

Ten structurally diverse chalcone-acetamide derivatives (AS2-1-AS2-10) were designed and synthesized to investigate their potential as analgesic and anti-inflammatory agents. The synthetic route involved Claisen-Schmidt condensation to form the α,β-unsaturated ketone framework, followed by etherification with modified 2-chloroacetamides, which introduced N-aryl and N-alkyl amide functional groups. All compounds were obtained in satisfactory yields under mild conditions and were structurally characterized using FTIR, 1H-NMR, 13C-NMR, and EIMS. In silico ADMET profiling indicated favorable drug-like attributes, including balanced lipophilicity, suitable polarity, and predicted gastrointestinal absorption, suggesting the oral viability of the compounds. Molecular docking studies showed a stronger binding affinity of AS2 derivatives with COX-2 than with COX-1, supported by hydrogen bonding and electrostatic interactions, thereby explaining their selective anti-inflammatory potential. Cytotoxicity evaluation using the MTT assay on normal murine fibroblast (3T3) cells revealed low toxicity toward the cell viability. COX isoenzyme inhibition studies identified AS2-2, AS2-5, and AS2-10 as the most potent COX-2 inhibitors, exhibiting low micromolar IC50 values and selectivity indices comparable to that of nimesulide. Consistently, in vivo pharmacological studies demonstrated significant suppression of nociceptive responses in acetic acid-induced writhing and formalin-induced paw licking models. Moreover, these derivatives markedly reduced inflammation in a carrageenan-induced paw edema model. The enhanced activity of AS2-2 (3-Cl), AS2-5 (2-NO2), and AS2-10 (4-F-benzyl) is attributed to substituent-driven electronic and lipophilic effects, which optimize the COX-2 interaction while limiting COX-1 inhibition. Collectively, the AS2 series represents promising, selective, and biocompatible lead scaffolds with dual analgesic and anti-inflammatory potential for preclinical development.