Aureonitol is a fungal metabolite that has been found inChaetomiumand has antiviral activity.1It inhibits replication of the influenza A subtype H3N2 with an EC50value of 30 nM at a multiplicity of infection (MOI) of 0.01. It also inhibits replication of laboratory-adapted and clinical isolates of H3N2 (EC50s = 100 and 312 nM, respectively), as well as clinical isolates of the influenza A subtype H1N1 (EC50= 417 nM). Aureonitol inhibits hemagglutination activity of H3N2 and H1N1.