Chemical composition of Cymbopogon citratus (DC.) Stapf essential oil and evaluation of its antifungal activities against phytopathogenic fungi

Abstract

Background: Cymbopogon citratus essential oil (EO) is used for its antifungal, antibacterial and allopathic activities. Its efficiency has been proven to be due to its compounds such as citral, β-myrcène, limonene, linalool and geranyl. Aim: The aim of this work is to characterize the chemical composition of EO obtained from grown introduced C.citratus commonly known as lemongrass and to investigate its antifungal activities against several fungi and oomycetes. By studying Botrytis cinerea mutants which are multidrug resistant (MDR), the genes resposable of resistance to the EO was determined. Material and methods: The EO was isolated by hydrodistillation from aerial parts. The chemical composition was analyzed using gas chromatography/mass spectrometry. The antifungal activities of the EO was assessed by in vitro assay against the following fungi: Fusarium oxysporum radicis lycopersici, Pythium ultimum, Rhizoctonia solani, Fusarium culmurum as well as Botrytis cinera and its MDR mutants. Results: The chemical composition of the EO showed that the major component is cis-citral. In vitro assays showed that the EO significantly inhibited the growth of the pathogenic fungi. Fusarium oxysporum radicis lycopersici and Pythium ultimum were the most sensitive fungi to EO with 100ppm and 150ppm as respective IC50. The EO direct effect was confirmed by studying Botrytis cinerea mutants that demonstrated the involvement of mrr1, MDR3 and artD genes in the resistance to the EO. These results suggest that the EO antifungal effect could be due to cis-citral component but also to the synergic interaction between the different compounds present in the EO mixture. Conclusion: As a natural product, C.citratus EO has the potential to be used as a direct antifungal against necrotrophic, soil born and oomycetes fungi.