Abstract
BACKGROUND: Dengue fever continues to exert significant global impact, affecting populations worldwide with considerable public health and economic consequences. There is no antiviral drug for dengue. This study focuses on hypericin, a naturally occurring compound from Hypericum perforatum L. whose anti-dengue properties have been underexplored. We systematically examined its antiviral efficacy against dengue virus (DENV), revealing strong inhibitory effects and clarifying its precise antiviral mechanism. METHODS: The study assessed the efficacy of hypericin against DENV using various scientific methods like plaque assays and Western blotting. We looked into its antiviral mechanism. We used a time-of-addition approach during our research. Moreover, the basic mechanisms involved were studied through molecular docking, surface plasmon resonance (SPR), and co-immunoprecipitation (Co-IP). RESULTS: This study demonstrated that hypericin exhibits broad-spectrum antiviral activity against DENV-2 in cell lines derived from multiple species. In time-of-addition experiments, it showed inhibitory effects under co-treatment, direct virucidal, and post-treatment conditions. Crucially, hypericin primarily blocked viral attachment and entry stages, thereby effectively reducing intracellular viral load. Mechanistic investigations revealed a interaction between hypericin and the E protein, evidenced by a computational docking score of -7.0 kcal/mol and an experimental SPR-derived Kd of 7.18 µM. Furthermore, Co-IP assays demonstrated that hypericin competitively blocks the association between the E protein and its cellular receptor, HSP70. CONCLUSION: As per these findings, the E protein was seen to be a target of hypericin with an antiviral activity against DENV-2 at multiple stages by limiting viral adsorption and viral entry projecting a molecular basis for the candidate molecule as a possible anti-dengue agent.