Synthesis of Oxadiazole Derivatives and Evaluation of Antibacterial Activity against Escherichia coli

Oxadiazole derivatives are one of the most significant types of heterocyclic compounds in medicinal chemistry, which are characterized by their broad range of biological activities such as antibacterial, antifungal, anticancer, anti-inflammatory and antiviral properties. Gram-negative bacteria, including Escherichia coli, have become increasingly resistant to many of the common antibiotics used in recent years, leading to the search for new, more effective and less toxic antibacterial agents. Oxadiazole derivatives gained significant interest due to their level of pharmacological properties, electron deficient aromatic structure and bio-target interaction. The chemistry, synthetic methods, structure–activity relationships and antibacterial activity of oxadiazoles against Escherichia coli are discussed in this review. A variety of synthetic approaches to 1,2,4-oxadiazole and 1,3,4-oxadiazole derivatives are reviewed, such as cyclisation reactions, oxidative condensation and microwave-assisted synthesis. Also discussed are the mechanisms of antibacterial action, and the effect of substituents on the activity. In addition, some recently published oxadiazole derivatives with high inhibitory activity against resistant bacterial strains are highlighted. The review highlights the significance of oxadiazole scaffolds as potential promising candidate drugs for further development in the field of antibacterial agents.