Evaluation of physcion isolated from endophytic Aspergillus fumigatus ASH3 as an antiviral agent against coxsackievirus B4 and herpes simplex virus type 1: in silico-supported in vitro study.

Physcion, an anthraquinone compound from the endophytic fungus Aspergillus fumigatus ASH3, isolated from Lotus hebranicus, has been studied for its antiviral activity against Coxsackievirus B4 (CVB4) and Herpes simplex virus type 1 (HSV-1) in the in silico and in vitro study. The MTT assay was performed to investigate cytotoxicity on Vero cells with CC₅₀ of 452.25 ± 4.91 µg/mL and maximum non-toxic concentration (MNTC) of 125 µg/mL, indicating that physcion has relatively low cytotoxicity. At the MNTC, physcion displayed potent antiviral activity with inhibition rates of 90.52% for CVB4 and 83.22% for HSV-1. The IC₅₀ for CVB4 was 70.7 ± 0.86 µg/mL, while HSV-1 was 78.23 ± 0.83 µg/mL; both of which had selectivity index values (SI = 6.40 and 5.78, respectively) that indicate a wide therapeutic index and potent antifungal activity, respectively. Molecular docking studies showed that physcion interacts stably with several viral protein targets, such as HSV-1 DNA polymerase-processivity factor (PDB: 8OJA), HSV UDG (PDB: 5AYS), and the CVB4 terminase complex (PDB: 6M5U), with binding energies from − 5.8 to -7.5 kcal/mol. The docking poses made meaningful hydrogen bonds with key residues such as Ser1183, Lys1136, ArgA134, TyrA138, and Gln223, as well as supporting hydrophobic interactions and π–π stacking that stabilizes the binding. Molecular dynamics simulations confirmed the complexes remained conformationally stable during the 100 ns trajectories with RMSD fluctuations of ≤ 2 Å and maintained hydrogen-bond occupancies. The ADMET profile suggested stringent plasma-protein binding (99.49%), adherence to Lipinski’s and Golden-Triangle rules, modest oral absorption, and low cardiotoxicity (hERG = 0.04), supporting its potential as an orally bioavailable antiviral lead. Overall, the combined in vitro and computational results show physcion is a safe, naturally-derived antiviral candidate with dual activity against human viruses, regardless of enveloped or non-enveloped types. This study represents the first report of the antiviral activity of physcion isolated from A. fumigatus ASH3, positioning it as a promising scaffold to develop novel broad-spectrum antiviral therapeutics.