3-Aryl-1,2,4-oxadiazole Derivatives Active Against Human Rhinovirus

The human rhinovirus (hRV) is the causative agent of the common cold that often aggravates respiratory complications in patients with asthma or chronic obstructive pulmonary disease. The high rate of mutations and variety of serotypes are limiting the development of anti-hRV drugs, which emphasizes the need for the discovery of novel lead compounds. Previously, we identified antiviral compound 1 that we used here as the starting material for developing a novel compound series with high efficacy against hRV-A and -B. Improved metabolic stability was achieved by substituting an ester moiety with a 1,2,4-oxadiazole group. Specifically, compound 3k exhibited a high efficacy against hRV-B14, hRV-A21, and hRV-A71, with EC₅₀ values of 66.0, 22.0, and 3.7 nM, respectively, and a relevant hepatic stability (59.6 and 40.7% compound remaining after 30 min in rat and human liver microsomes, respectively). An in vivo study demonstrated that 3k possessed a desirable pharmacokinetic profile with low systemic clearance (0.158 L·h^-1·kg^-1) and modest oral bioavailability (27.8%). Hence, 3k appears to be an interesting candidate for the development of antiviral lead compounds.