In vitro antiviral potential of H. helix L. and V. thapsus L. on Vero cell adapted human parainfluenza virus (HPIV) With molecular docking insights

Introduction: Human parainfluenza viruses (HPIVs) are significant contributors to respiratory infections worldwide, with a lack of effective antiviral therapies. This study investigates the antiviral potential of bioactive saponins extracted from H. helix (常春藤) and V. thapsus (毛蕊花), two medicinal plants traditionally used for respiratory ailments. This study evaluates the antiviral potential of H. helix L. (ivy) and V. thapsus L. (mullein), two medicinal plants with traditional uses in herbal systems, including therapeutic parallels in Traditional Chinese Medicine (TCM), against HPIV using Vero cell lines. Methods: Plant extracts were prepared using ethanol extraction, followed by dilution and characterization via HPLC and HNMR to identify saponins. In vitro antiviral assays were conducted on Vero cell lines infected with HPIV, assessing pre-, post-, and simultaneous treatments. Hemagglutination assay quantified viral activity. Molecular docking of major saponins against HPIV’s HN protein was performed to predict interaction mechanisms. Results: HPLC identified hederacoside C, hederacoside D, and α-hederin in H. helix, and thapsuine A in V. thapsus. HNMR spectra supported the presence of complex saponin structures. Both extracts demonstrated dose-dependent antiviral activity, with H. helix exhibiting the most potent inhibition at 40 µg/mL, particularly when administered before infection. Molecular docking revealed strong binding affinities of hederacoside C and α-hederin with the HN protein, indicating a potential mechanism of action. Conclusion: The results suggest that H. helix and V. thapsus possess significant anti-HPIV activity, likely mediated by saponins disrupting viral replication. This study highlights the promise of H. helix and V. thapsus as natural antiviral agents within an integrative TCM framework, paving the way for future research into their clinical applications against respiratory viral infections.