Publication date: Jun 26, 2025

The COVID-19 (coronavirus disease 19) pandemic has underscored the urgent need for effective antiviral agents targeting viral entry mechanisms. This study investigated the inhibitory effects of heparan sulfate (HS) and enoxaparin (EX) on the interaction between the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein and the angiotensin-converting enzyme 2 (ACE2) receptor. A pseudovirus model was employed to evaluate the efficacy of HS and EX under different treatment strategies: pre-treatment of host cells, pre-treatment of the viral particles, and simultaneous co-treatment. Both compounds significantly inhibited viral entry. EX exhibited a dose-dependent effect under all treatment conditions. In cell pre-treatment, EX achieved the highest levels of inhibition, whereas HS demonstrated consistent inhibitory activity that was largely concentration-independent. Viral pre-treatment revealed that both compounds effectively reduced infectivity by interfering directly with viral particles. In the co-treatment experiments, HS demonstrated superior inhibitory activity at lower concentrations compared to EX. The results suggested that HS and EX inhibit SARS-CoV-2 entry via distinct mechanisms. HS likely acts via competitive inhibition at the host cell surface, while EX may bind directly to the spike protein, thereby preventing engagement with the ACE2 receptor. These findings highlight the therapeutic potential of HS and EX as entry inhibitors targeting the early stages of SARS-CoV-2 infection. Further studies are warranted to evaluate their efficacy against emerging variants and in vivo models.

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