Design, Synthesis, Molecular Docking, and Nanoformulation of Novel Diclofenac–Benzimidazole Hybrid Analogues Loaded into Biodegradable PLGA Nanocarriers for Improved Anti-Inflammatory Activity and Gastroprotective Potential

Abstract

Background: Diclofenac is a widely prescribed nonsteroidal anti-inflammatory drug (NSAID) used for the treatment of pain and inflammation; however, its long-term administration is frequently associated with gastrointestinal adverse effects. Molecular hybridization and nanotechnology-based drug delivery systems offer promising strategies for improving therapeutic efficacy while minimizing toxicity. Objective: The present study aimed to design, synthesize, and evaluate novel diclofenac–benzimidazole hybrid analogues and develop PLGA-based nanoformulations with enhanced anti-inflammatory activity and gastroprotective potential. Methods: A series of diclofenac–benzimidazole hybrid analogues were designed using molecular hybridization principles and subjected to molecular docking against cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF α), and nuclear factor-kappa B (NF-κB). The synthesized compounds were characterized using FTIR, ^1H NMR, LC MS, and elemental analysis. The lead compound (DBH-7) was encapsulated into biodegradable poly(lactic-co glycolic acid) (PLGA) nanoparticles using the solvent evaporation method. The nanoformulation was characterized for particle size, polydispersity index, zeta potential, encapsulation efficiency, morphology, and in vitro drug release behavior. Anti-inflammatory activity was evaluated through COX inhibition assays, cytokine suppression studies, and carrageenan-induced paw edema models. Gastroprotective effects were assessed using ulcer index determination and histopathological examination. Results: Molecular docking studies revealed that DBH-7 exhibited the highest binding affinity toward COX-2 (−9.8 kcal/mol), TNF-α (−8.1 kcal/mol), and NF-κB (−8.0 kcal/mol), outperforming diclofenac. The synthesized hybrids were obtained with yields ranging from 68–89% and purity exceeding 96%. DBH-7-loaded PLGA nanoparticles displayed a mean particle size of 168.4 ± 6.2 nm, polydispersity index of 0.184 ± 0.02, zeta potential of −24.7 ± 1.4 mV, and encapsulation efficiency of 88.6 ± 2.1%. Sustained drug release was observed over 72 h with cumulative release of 89.4%. The nanoformulation demonstrated superior COX-2 selectivity, significant suppression of TNF-α and IL-6 production, and enhanced inhibition of carrageenan-induced paw edema (85.6%) compared with diclofenac (58.4%). Furthermore, DBH-7-loaded PLGA nanoparticles markedly reduced gastric ulceration and preserved gastric mucosal architecture. Conclusion: The combination of diclofenac–benzimidazole molecular hybridization and PLGA nanoencapsulation 
successfully produced a multifunctional therapeutic system with enhanced anti-inflammatory efficacy, improved 
COX-2 selectivity, sustained drug release, and significant gastroprotective effects. DBH-7-loaded PLGA 
nanoparticles represent a promising candidate for the development of safer and more effective anti-inflammatory 
therapies.