Use of Essential Oils for the Treatment of Fusarium oxysporum f. sp. Albedinis: Chemical Profile, In Vitro Antifungal Activity, and In Silico Investigation by Molecular Docking Study

Abstract

Background: Fusarium oxysporum f. sp. Albedinis a telluric fungal pathogen commonly found in soils, is the causal agent of fungal vascular wilt of date palms in Moroccan oases. The infection by the pathogen leads to the death of the date palm after six months to two years, which causes enormous economic and environmental damage. Objective: The framework of this paper is to determine the chemical composition of six essential oils using GC-MS and their antifungal activity on the mycelial growth of Fusarium oxysporum f. sp. Albedinis, as well as the molecular docking study to evaluate the inhibitory potential of fungal trypsin. Methods: The essential oils were extracted from different parts of the plants (whole plant, flowers, and leaves) by steam distillation, and were identified using gas chromatography-mass spectrometry (GC/MS). The antifungal assay of the extracted essential oils and their main components was assessed using the direct contact method with the fungus at different concentrations; the obtained results were evaluated by calculating the minimum inhibitory concentration (MIC) of each essential oil, followed by an in-silico study of the major identified compounds for better understanding of the inhibitory potential against fungal trypsin activity. Results: The identification of the different bioactive compounds using GC-MS revealed that Rosmarinus officinalis Eo was characterized by eucalyptol 46.26%, camphor 10.03%, and β-pinene 6.63%; while Lavandula officinalis Eo was endowed by the presence of linalool 14.93%, camphor 14.11%, and linalyl acetate 11.17%. Furthermore, Artemisia herba alba was rich in 1,3,5-cycloheptatriene, 1,6- dimethyl- 36.44%, camphor 22.50%, and α-thujone 7.21%. While Eucalyptus globulus was rich in eucalyptol 74.32%, β-Cymene 11.41%, α-Pinene 6.96%. Finally, Mentha pepirita and Mentha pulegium were both characterized by the presence of D-limonene 20.15%, trans-carveol 19.59%, D-Carvone 14.96%, and pulegone (42.40%), 3-cyclopentene-1-ethanol, 2,2,4-trimethyl- (11.28%), 1,3,4- trimethyl-3-cyclohexenyl-1-carboxaldehyde (9.68%), respectively. Regarding the in vitro, all Eos from different plants exhibited pronounced antifungal effect. The MIC values recorded for E. globulus were MIC= 1.75 mg/L, M. pulegium and L. officinalis (MIC= 1.80 mg/L), and M. piperita (MIC= 1.90 mg/L). The strongest inhibition potential was associated with R. officinalis EO (MIC= 1.15 mg/L) and A. herba alba EO (MIC= 1.60 mg/L). As for the computational study performed camphor one of the bioactive compounds showed its ability to act against trypsin which could be considered a potential candidate against Fusarium oxysporum f. sp. Albedinis. Conclusion: The studied essential oils from different medicinal and aromatic plants showed significant antifungal activity, probably due to the Camphor which could have an inhibitory effect on the Fusarium oxysporum f. sp. Albedinis trypsin. Further research should be conducted in vivo for a better understanding of the mechanism of action of these essential oils.