Research Of Antifungal Activity And Mechanisms On Natural Source Phthalide And Isothiocyanate Compounds

In view of the resistance of traditional chemical fungicides to plant pathogenic fungi and the threats to the safety of human and environmental,there is an urgent need to find safe and efficient alternatives to natural products.Based on the previous research,this study evaluated antifungal activity of Angelica sinensis（Oliv.）Diels oil and its main phthalide compounds and natural source of isothiocyanates compounds against 6kinds of common plant pathogen fungi Rhizoctonia solani（R.solani）,Botrytis cinerea（B.cinerea）,Fusarium graminearum（F.graminearum）,Fusarium oxysporum f.sp.vasinfectum（F.oxysporum）,Sclerotinia sclerotiorum（S.sclerotiorum）,Magnaporthe oryzae（M.oryzae）and Aspergillus niger（A.niger）,Aspergillus flavus（A.flavus）.Then,it is investigated the mechanism of action of of some most-active compounds.Through the above research,we hope to find efficient safety of botanical pesticides.The main contents are described as follows:Part 1:Chemical composition of Angelica sinensis（Oliv.）Diels oil and antifungal mechanism of phthalides.In this paper,the volatile oil of Angelica sinensis（Oliv.）Diels was extracted and analyzed while the antifungal activity of four main phthalide compounds and essential oil in Angelica sinensis（Oliv.）Diels was evaluated against six plant pathogenic fungi.Among them,3-Butylidenephthalide（3-BPH）displayed the best antifungal activity against F.graminearum.The transcriptome of F.graminearum was analyzed after treatment with 3-BPH,which showed that 3-BPH could affect ergosterol biosynthesis and the degree of lipid peroxidation of cell membrane in F.graminearum.Moreover,we investigated the possible action mechanisms of the 3-BPH in RNA level based on transcriptomics and validated the related genes and experiments.The above study is expected to provide a valuable reference for finding new plant-derived fungicides.Part 2:The antifungal activity and action mechanism of the natural sources isothiocyanates and their analoguesPrevious studies have shown that isothiocyanates have a good antifungal activity.This chapter firstly screened the antifungal activities of 18 isothiocyanates against eight common fungi.Two dominant compounds were selected to study the synergistic effect of antifungal activity.As a result,we found that 1-（2-Isothiocyanatoethyl）-4-methoxybenzene has the best activity against A.niger,with an EC₅₀ value of 4.19μg/m L.Therefore,we chose A.niger as the target to research the action mechanisms of 1-（2-Isothiocyanatoethyl）-4-methoxybenzene,including observe the morphological changes,measure cell membrane integrity,the content of MDA,mitochondrial membrane potential,endogenous ROS,and the enzyme activities related to mitochondrial function.The results showed that 1-（2-Isothiocyanatoethyl）-4-methoxybenzene may affect the activity of mitochondria by inducing the production of ROS,further affect the TCA cycle process,disrupt REDOX homeostasis,and thus play an antifungal role.