CHIKV nsP2 protease-IN-2 (Compound 2o) is an allosteric inhibitor of the non-structural protein 2 helicase (nsP2hel), with IC50 values of 0.5 μM for nsP2 ATPase and 0.9 μM for RNA helicase. It exhibits broad-spectrum antiviral activity against alphaviruses, effectively targeting Chikungunya virus (CHIKV), Mayaro virus (MAYV), and Venezuelan equine encephalitis virus (VEEV), with an EC50 of 0.12 μM against CHIKV-nLuc. This compound is useful for research on alphavirus infections.