Discovery of Phytochemicals as Inhibitors of Human Metapneumovirus: In-Silico Docking Studies

Human metapneumovirus (HMPV) remains a leading cause of severe paediatric and geriatric respiratory morbidity, manifesting in pathologies from bronchiolitis to pneumonia. Despite its clinical burden, no licensed vaccines or targeted antivirals exist. This study utilizes an advanced computational pipeline to identify novel therapeutic leads targeting two high-consequence viral proteins: the Fusion (F) protein, essential for viral-cell entry, and the M2-1 matrix protein, a critical processivity factor for viral replication.

A library of plant-derived bioactive compounds was screened using an integrated in silico framework. Molecular docking was performed using AutoDock Vina to quantify binding energies. The structural stability and conformational flexibility of the top-ranking ligand-protein complexes were rigorously validated through 100ns molecular dynamics (MD) simulations using the Desmond module. Furthermore, ADMETlab 3.0 was utilized to perform comprehensive pharmacokinetic profiling and toxicity assessments.

Several phytochemicals demonstrated superior binding efficacy compared to the reference antiviral ribavirin (Glide binding scores: -5.6 to -7.6 kcal/mol). Notably, somniferine and 17-α-hydroxy withanolide D were identified as the most promising candidates, exhibiting exceptional affinity for both F and M2-1 targets, with high binding scores. Other high-affinity leads include withanolide derivatives (C, L, D, and S) and sitoindoside IX. MD simulations confirmed that these phytochemicals maintained high structural stability within the binding pockets, characterized by minimal RMSD fluctuations.

Considering high binding affinities as well as stabilities of the docked poses confirmed with MD simulations studies shows that withanolide derivatives are capable of inhibiting key proteins of HMPV, which are responsible for viral entry and replication. The high binding affinity as well as sustained interactions of somniferine and 17-α-hydroxy withanolide D at active sites of F and M2-1 proteins indicate that these phytochemicals present in plants may act as potential lead compounds for drug development against HMPV.

These findings identify somniferine and related withanolides, especially 17-α-hydroxy withanolide D, as promising scaffold candidates for HMPV therapeutic development. Their favourable drug-likeness and superior binding energies relative to ribavirin suggest high potential for further optimization. While these in-silico results are robust, subsequent in-vitro neutralizing assays and in-vivo toxicity studies are warranted to translate these leads into clinically useful agents.