Fungicidal And Nematicidal Activities Screening Of Ten Species Of Tropical Plants As Well As Identification Of Their Active Components

In this paper,Fungicidal and insecticidal activities of 10 tropical plants were studied.The research contents and results are as follows:1.Fungicidal and insecticidal activities of the extracts of 10 tropical plants against 10 phytopathogenic fungi and Meloidogyne incognita(J2)were determined.The results of bioassay showed that each plant extract showed different degrees of fungicidal and insecticidal activities.The extracts of Waltheria Indica and Helicteres angustifolia have the obvious biological activity.At 500 ?g/mL,the mycelial growth inhibition rate of CH2Cl2 extract of the stem of Waltheria Indica against 5 phytopathogenic fungi(Botryosphaeria dothidea,Collelotrichum musae,Pestalotipsis guepinii,Phylophthora nicotianae,Sclerotinia sclerotiorum)were more than 70%.Especially,the mycelial growth inhibition rate of CH2Cl2 extract of the stem of Waltheria Indica against Sclerotinia sclerotiorum reached 100%.The EC50 values of CH2Cl2 extract of the stem of Waltheria Indica against the 5 plant pathogenic fungi were 129.8 ?g/mL,46.60 p.g/mL,59.28?g/mL,198.80 ?g/mL,49.47 ?g/mL,respectively.The relative inhibitory rates of CH2Cl2 extract of the stem of Waltheria Indica on the spore germination against Colletotrichum musae were more than 80%at 50 ?g/mL and 100 ?g/mL.In vivo antifungal evaluation against the Colletotrichum musae showed that the control effect of CH2Cl2 extract of the stem of Waltheria Indica was 86.95%at 5 mg/mL.The results of the pot experiment showed that the control effect of the stem CH2Cl2 extract of Waltheria Indica against the Sclerotinia sclerotiorum was 89.23%at 5 mg/mL.In the pot experiment,the control effect of the stem CH2Cl2 extract of Waltheria Indica against the Pseudoperonospora cubensis,Erysiphe cichoracearum,Phakopsora pachyrhizi and Colletotrichum orbiculare were over 70%at 10 mg/mL.In the screening of nematicidal activity,the CH2Cl2 extracts of the leave,stem and root of Waltheria Indicas showed strong nematocidal activity against Meloidogyne incognita,for example,the corrected morality rate reached 100%at 500 ?g/mL and the 24 h ECso values were 36.24 ?g/mL,51.75?g/mL and 53.13 ?g/mL respectively.The mycelial growth inhibition rate of the root petroleum ether and ethyl acetate extracts of Helicteres angustifolia against Colletotrichum musae reached 76.50%and 68.92%at 500 mg/mL,and the EC50 values was 0.062 mg/mL and 0.052 mg/mL respectively.The relative inhibitory rates of the root petroleum ether and root ethyl acetate extracts of Helicteres angustifolia on the spore germination of Collelotrichum musae were more than 70%at 2 mg/mL,4 mg/mL and 8 mg/mL.In vivo antifungal evaluation showed that the control effects of the petroleum ether and ethyl acetate extracts of the root of Helicteres angustifolia against Colletotrichum musae were 72.32%and 59.77%,respectively.2.The active components of the dichloromethane extract of the stem of Waltheria Indica were bioassay-guided isolated by TLC,silica gel column chromatography and Sephadex LH-20 column chromatography.Compounds 1 and 2 have fungicidal activities and compound 3 has nematicidal activity.Further strucuture identification of compounds 1-3 was carried out by 1H-NMR,13C-NMR and HRMS.Finally,compound 1-3 were determined as Antidesmone,Waltherione C and Waltherione A through comparison with the literature data.The bioassay results showed that Antidesmone have broad-spectrum antifungal activity and the antifungal activity was even better than that of commercial botanical fungicides(carvacrol,eugenol and osthole),the ECso values of Antidesmone against 5 phytopathogenic fungi were 20.15 ?g/mL,10.80?g/mL,6.45 ?g/mL,13.47 ?g/mL and 0.60 ?g/mL.The relative inhibitory rates of Antidesmone on the spore germination against Colletotrichum musae were more than 80%at 0.3 ?g/mL and 0.6?g/mL.The EC50 Values of Waltherione A against Meloidogyne incognitae was 0.394 ?g/mL.3.The components of the petroleum ether and ethyl acetate extracts of the root of Helicteres angustifolia were preliminarily analyzed by GC-MS.Generally,36 major chemical components were identified in the root petroleum ether extract and 17 major chemical components were identified in the root ethyl acetate extract.Among the 8 main compounds,diisobutyl phthalate and dibutyl phthalate showed high antifungal activity against Colletotrichum musae and the mycelial growth inhibition rate were 65.12%and 68.07%at 100 ?g/mL respectively.The EC50 values of diisobutyl phthalate and dibutyl phthalate were 56.66 ?g/mL and 37.04 ?g/mL respectively.It is speculated that the antifungal ingredients may be diisobutyl phthalate and dibutyl phthalate.