Molecular Docking Analysis of Bioactive Compounds from Cinnamomum zeylanicum Bark Essential Oil Targeting Chitin Synthase and 1,3-β-Glucan Synthase in Mycotoxigenic Fungi

Abstract

Mycotoxigenic fungi pose significant threat to food safety and global agriculture, necessitating the development of effective and sustainable natural antifungal agents. Cinnamomum zeylanicum bark essential oil (CBEO) is known for its broad antifungal activity; however, the molecular mechanisms underlying its effects remain poorly understood. In this study, an in silico approach was employed to investigate the inhibitory potential of Gas Chromatography–Mass Spectrometry(GC–MS)-identified CBEO constituents against two essential fungal cell-wall biosynthetic enzymes: chitin synthase (CHS) and 1,3-β-glucan synthase (FKS). Docking analyses were performed using AlphaFold-predicted protein structures and a binding energy threshold of ≤ -6.0 kcal/mol was set as benchmark based on established binding energies of known antifungal inhibitors: nikkomycin Z and caspofungin. Several CBEO compounds exhibited favorable binding affinities, indicating strong interactions with the catalytic regions of both enzymes. Benzyl benzoate (- 6.937 kcal/mol), copaene (-6.692 kcal/mol), and Acetate, cinnamyl ester (-6.311 kcal/mol) showed binding affinities comparable to nikkomycin Z against CHS, while alpha-phellandrene dimer (-8.211 kcal/mol), caryophyllenyl alcohol (-7.686 kcal/mol), and β- caryophyllene (-7.657 kcal/mol) surpassed the reference drug caspofungin against FKS. Interaction analyses revealed that hydrophobic interactions, π-alkyl bonds, and aromatic stacking played dominant roles in stabilizing the ligand-enzyme complexes. These findings indicate that CBEO contains multiple bioactive constituents capable of targeting fungal cell-wall biosynthesis through a multi-target mechanism, supporting its potential application as a natural antifungal agent for improving food safety and mitigating mycotoxin contamination in cereal products.