Synthesis of novel NSAIDs linked to triazolyl-oxadiazole heterocyclic compounds as more comprehensive antimicrobial agents: A computational molecular docking
Introduction: Progress in the development of triazolyl-oxadiazoles is a bisphosphonate-700 inhibitor is still continuing with an outcome of the good scaffold as oxadiazole as well as triazoles individually for antibacterial activity. Hence, we proposed a suitable approach for the synthesis of dual heterocyclic analogues consisting of the therapeutically used non steroidal anti-inflammatory drugs in a combined form and evaluated for their antibacterial, antifungal activities, docking studies. Methods: The chemical structures were confirmed by various spectroscopic methods like IR, 1H NMR, 13C NMR, mass, and elemental analysis. The antibacterial, antifungal activity of these compounds was screened against Gram-positive, Gram-negative bacteria and fungal stains by agar well diffusion method. The crystal structure of S. aureus complexed with active site of bisphosphonate BPH-700 (2ZCS) was obtained from the Protein Database (PDB, http://www.rcsb.org). Molecular properties, drug likeness score, lipophilicity and solubility parameters by Molinspiration and Molsoft software. 7f (2-NO2, 5-Ome), 7g (3-Cl, 4-Cl), 7a (2-NO2) Results: Among the synthesised NSAID-triazolyl-oxadiazole containing 2-nitro-5-methoxy (7f), 3,4-dichloro (7g) derivatives were found to be high active antibacterial agents against S. aureus, E. coli with MICs 16, 19 μg/mL respectively. 2-nitro-5-methoxy (7f), 4-bromo (7h) and 2-nitro (7a) derivatives displayed superior antifungal activity against A. niger and MICs 56, 76, 130 μg/mL respectively. From molecular docking NSAID linked to 3,4-dichloro analogue (7g) revealed stronger binding interaction (ΔG =7.90 Kcal/Mol) with amino acids Asp49 (1.19 A˚), Arg45 (2.17 A˚), Lys17, Lys46 in the active site of S. aureus complexed with bisphosphonate Bph-700 (2ZCS). The compounds followed the Lipinski ‘Rule of five’ were synthesized for antimicrobial screening as oral bioavailable drugs/leads. Maximum drug likeness model score 0.49, 0.41 was found for compounds 7h, 7b. Conclusion: The present work, through simple synthetic approaches, led to the development of novel hybrids of triazole-oxadiazole pharmacophores that exhibited remarkable biological activities against different microorganisms. The compounds showed suitable drug like properties and are expected to present good bioavailability profile. Discussion: An efficient combination of molecular modeling and biological activity provided an insight into QSAR guide lines that could aid in further development of these derivatives.