Broad-spectrum antiviral activity of benzothiazole-acrylamide hybrids against Zika, Dengue, Chikungunya, and Sindbis viruses

Abstract

Arboviral infections such as those caused by Zika (ZIKV), Dengue (DENV), Chikungunya (CHIKV), and Sindbis (SINV) viruses remain major global health concerns, aggravated by the absence of specific antiviral therapies. Given the overlapping endemicity and co-circulation of these pathogens, the development of pan-antiviral agents capable of simultaneously inhibiting multiple arboviruses is a pressing need. In this study, we report the rational design, synthesis, and biological evaluation of novel benzothiazole–acrylamide hybrid compounds with pharmacophores targeting both Flavivirus and Alphavirus proteases. The designed hybrids were synthesized via a pharmacophore-hybridization strategy combining benzothiazole and acrylamide scaffolds previously associated with anti-ZIKV/DENV and anti-CHIKV activities. Enzymatic assays revealed selective allosteric inhibition of ZIKV NS2B/NS3 protease (IC50 values down to 13.6 μM), with negligible effects against the homologous DENV2 enzyme. The most promising compounds exhibited submicromolar antiviral potency in plaque-reduction assays against ZIKV, CHIKV, and SINV, achieving EC50 values below 1.9 μM and selectivity indices above 16. Notably, compound LQM560 demonstrated robust and balanced activity against all three viruses, as confirmed by qRT-PCR and immunofluorescence analyses, highlighting its pan-antiviral profile. Mechanistic assays indicated an allosteric mode of inhibition toward ZIKV protease, while CHIKV suppression likely involves interference with early replication stages rather than nsP2 protease inhibition. Molecular dynamics and MM/GBSA analyses supported the stability of ligand–NS2B/NS3 complexes, consistent with experimental findings. Overall, this work identifies benzothiazole–acrylamide hybrids as a new class of pan-antiviral small molecules, offering a promising chemical framework for broad-spectrum therapeutic development against emerging arboviruses of medical relevance.