Identification And Action Mechanism Of Essential Oils And Active Components To Phytopathogenic Fungi

The increasing concern over environmental effects and food safety caused byorganic synthetic pesticides has highlighted the need for alternative products.Pesticidal activity screening from plants could lead to the discovery of new pestcontrol agents. In this study, tweleve essential oils were applied to screen the oneswith a better inhibition rate of plant pathogenic fungi. Separation, purification andidentification of antifungal ingredients of cinnamon oil, geranium oil, mint oil werecarried out under the bioassay-guided fractionation method. The results are asfollows:1. The experiment distilled the essential oils of aromatic plants. The antifungalactivities of tweleve essential oils were measured with mycelial growth method, withPythium aphanidermatum, Pythium μltimum, Fusarium oxysporium, Fusariumsolani, Botrytis cinerea and Fusarium graminearum as test strains. The resultsindicated that all the tested essential oils possessed the antifungal activities againstsix fungi at the concentration of2g/L, especially the antifungal activities of sixessential oils including citronella oil，cinnamon oil，geranium oil, lavender oil, teatree oil and mint oil was excellent with100%inhibition rate against all the tested sixplant pathogenic fungi. The effects of cinnamon oil, geranium oil, mint oil on sporegermination of B. cinerea were examined. There was a significant inhibition offungal spore germination.2. Under the bioassay-guided fractionation method, we obtained three activeantifungal substances, namely PCa、MCb and CBb after purification steps of TLCand silica gel column chromatography of cinnamon oil, geranium oil and mint oil.The EC50of PCa against F. graminearum and B. cinerea was83.30μg/mL and52.12μg/mL respectively, MCb possessed the EC50value of172.24μg/mL and52.23μg/mL, while CBb possessed the EC50value of41.6μg/mL and45.67μg/mL against F. graminearum and B. cinerea respectively. We further determined the threesubstances by1H-NMR, and data comparisons were carried out. Finally, PCa wasdetermined as citronellol, MCb was menthol, and CBb was Cinnamaldehyde.3. Micropscopic observation revealed that the mycelia of B. cinerea appeaerddistortion, with protoplasm agglomerated and leaking of cell contents on the effect ofantagonistic substance. After treatment of citronellol, cinnamaldehyde, Menthol, theinclusion of mycelium, glucose content, soluble proteins, NADH oxidase andchitinase activity were different with that of control.