In Silico and In Vitro Antifungal Investigations of Verbascoside Isolated From Verbascum Ozturkii

Abstract

This study investigates the antifungal properties of verbascoside isolated from Verbascum ozturkii. The primary objective is to evaluate its efficacy against two agriculturally significant plant pathogens, Phytophthora infestans and Verticillium dahliae. Verbascoside was isolated using preparative high-performance liquid chromatography (HPLC) and its structure was elucidated via nuclear magnetic resonance (NMR) spectroscopy. In vitro antifungal assays demonstrated moderate inhibitory effects with verbascoside (2 mg/mL) reducing mycelial growth by 23.49% for P. infestans and 19.42% for V. dahliae. To elucidate the antifungal mechanism, quantum chemical calculations and molecular docking studies were conducted. Analyses of frontier molecular orbitals (HOMO-LUMO) and molecular electrostatic potential (MEP) identified critical interaction sites. Molecular docking demonstrated that verbascoside binds favorably to the protein structures of V. dahliae (PDB: 5xmz) and P. infestans (PDB: 6jyg). Molecular dynamics simulations confirmed the stability of these interactions with molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) calculations indicating more favorable binding free energy for the verbascoside-6jyg complex. This research underscores the potential of verbascoside as a natural antifungal agent highlighting the significance of protein-specific interactions. The findings contribute to the development of alternative antifungal strategies and emphasize the novelty of verbascoside activity against these plant pathogens.