Structure-based profiling of putative therapeutics against monkeypox virus VP39 using pharmacophore modelling and molecular dynamics simulation studies.

The growing global health threat of the monkeypox virus (MPXV) underscores the critical need for effective antiviral agents, since there are currently no therapeutics. The MPXV VP39, a methyltransferase, is essential for viral replication, hence a potential target for anti-MPXV drug candidates. Herein, a structure-based pharmacophore modelling and molecular docking approach was employed to screen natural compounds (NCs: 581,426) from the COCONUT database for potential inhibitors of MPXV VP39. After ranking of the docking scores, an ensemble-based docking of the top-ranked 20 NCs against multiple conformations obtained from ttcluster analysis of the molecular dynamics simulation trajectory of unbound MPXV VP39 further identified five leads with favourable interaction profiles, drug-likeness, ADMET properties, and synthetic features when compared to the reference standard (sinefungin). Further analysis of the thermodynamic stability of the resulting complexes of the leads over a 100-ns MD simulation period revealed varying degrees of thermodynamic stability while maintaining the structural integrity of MPXV VP39. Furthermore, the thermodynamic binding free energy calculation, while corroborating the docking analysis, identified CNP0297833 (-39.07 kcal/mol), CNP0371756 (-25.76 kcal/mol), and CNP0402319 (-19.26 kcal/mol) as the most promising candidates, with better modulatory effect against MPXV VP39 relative to sinefungin (-3.68 kcal/mol). These leads were stabilised with hydrophobic (Phe115, Val139, and Val116) and electrostatic (Glu46 and Asp138) interactions in different conformational clusters. In addition to the observed consistent interaction patterns, favourable binding energies, pharmacokinetics, ADMET, thermodynamic stability, and molecular orbital energies of these leads, the potential for optimisation for enhanced binding features for the active site of MPXV VP39 was elucidated. Further in vitro investigation to validate these findings is suggested to establish the putative leads as therapeutics targeting the replication phase of MPXV.