Design, synthesis and evaluation of a series of acyclic fleximer nucleoside analogues with anti-coronavirus activity

Abstract

A series of doubly flexible nucleoside analogues were designed based on the acyclic sugar scaffold of acyclovir and the flex-base moiety found in the fleximers. The target compounds were evaluated for their antiviral potential and found to inhibit several coronaviruses. Significantly, compound 2 displayed selective antiviral activity (CC₅₀ >3× EC₅₀) towards human coronavirus (HCoV)-NL63 and Middle East respiratory syndrome-coronavirus, but not severe acute respiratory syndrome-coronavirus. In the case of HCoV-NL63 the activity was highly promising with an EC₅₀ <10 μM and a CC₅₀ >100 μM. As such, these doubly flexible nucleoside analogues are viewed as a novel new class of drug candidates with potential for potent inhibition of coronaviruses.