Comparison of extraction methods for the determination of essential oil content, composition and antifungal activity of different plant species

Abstract

Plant essential oils (EOs) are gaining interest as biopesticides for crop protection. The antifungal effect of some EOs is one of their most important crop protection properties. In addition to these direct effects on the pathogen, it has been reported that EOs can induce plant defenses (priming effects) resulting in better protection against the pathogen. Considering the growing importance of EOS as active ingredients, the domestication and cultivation of Aromatic and Medicinal Plants (AMPs) to produce chemically stable EOs contributes to species conservation, provides sustainability of the production and lower variations in active ingredients. Otherwise, the essential oil content and consequently their bioactivity can vary with development stage and by extraction methods. The aim of the study was to compare a laboratory distillation in a Clevenger apparatus and steam distillation in a pilot plant to extract EOs from plant species belonging to the genera Artemisia, Dittrichia, Geranium Lavandula, Mentha, Origanum, Rosmarinus, Salvia, Satureja, Santolina, Tanacetum and Thymus experimentally cultivated. The Eos were analyzed by GC-MS and tested in vitro against phytopathogenic fungi (spores of Alternaria alternata, Botrytis cinerea, Fusarium oxysporum) to select the most active and les phytotoxic one (against Lolium perenne) as plant candidates. Differences in activity and composition have been found between the laboratory and pilot plant extracted oils. Therefore, the semi-industrial conditions for the extraction of bioactive EOs must be optimized case by case to improve the EO content in bioactive compounds.