Study On Antifungal Activity Of Extracts Of Five Medicinal Plants And Antifungal Active Components Of Leonurus Japonicus

In this paper,the excessive and unreasonable use of traditional chemical pesticides has caused great impact on the environment and human health.Therefore,people pay more and more attention to plant pesticides with low toxicity and friendly environment.The inhibitory activity of methanolic extracts of five medicinal plants,including Leonurus japonicus 、 Mentha haplocalyx Briq 、 chizonepeta tenuifolia Briq 、 Fructus Kochiae Scopariae、Salvia chinensia Benth,against eight kinds of fungus(Colletotrichum siamense、Pseudopestalotiopsis camelliae-sinensis 、 Colletotrichum gloeosporioides 、 Alteraria alternata、Fusarium oxysporum、Neofabraea actinidiae、Physalospora piricola Nose)was evaluated.The chemical constituents of Leonurus japonicas were isolated,identified and screened by modern separation techniques.The main results are as follows:1.When the concentration of each plant extract was 5 mg/m L,the inhibition rates of Leonurus japonicas against Physalospora piricola Nose and Fusarium oxysporumf sp.niveum were 95.4% and 52.6%,respectively.The inhibition rates of Fructus Kochiae Scopariae against Colletotrichum siamense,Colletotrichum gloeosporioides,Fusarium oxysporum and Physalospora piricola Nose were 71.7%,70.7%,67.8% and 52.9%,respectively.The inhibition rates of the crude extracts from other plants were all lower than50%.2.Through various extraction and separation methods and pop technology,a total of13 compounds were isolated and identified from Leonurus japonicas.Including 2 steroids,5 hemihelianoid diterpenes,1 flavonoid,1 triterpene,1 riboflavin and 3 other compounds.In these compounds,two new compounds include one semiduranoid diterpenes: 12(Leonurusjap)and one arbuusursolic: 13(Leonurusursolic).In addition,compounds 1,5,6and 7 were isolated from Leonurus for the first time.3.The bacteriostatic effects of compounds 2-4,7-9 and 11 were tested at 200μg/ml.The results showed that all of them had different degrees of inhibitory activity,among which compound 3,7,8,9,11 had inhibition rates of more than 50%,and it was worth noting that compound 11 had the highest inhibition rate of 99.4% against Fusarium oxysporumf sp.niveum.The results showed that the crude extracts of 5 kinds of medicinal plants selected in this experiment had different degrees of inhibitory activity against 8 kinds of plant pathogens tested,among which the stronger inhibitory activities were Leonurus japonicas and Fructus Kochiae Scopariae.Through the study on the active components of Leonurus,it was found that some compounds had strong inhibitory activity against the pear rustellaria and the inhibitory rate was as high as 99.4%.The above results will provide some reference for the research and development of plant fungicides.