| Based on chemical pretest and bioassay results, with TMV as test organism, some active plants were intentionally screened. According to the bioassay results on TMV, some active substances in the selected plants were extracted, purified and identified. Effection on Brevicoryne bressicae (a virus spreading vector ), bacteria and fungi were also bioassayed. Structure-activity relationship was analyzed with the results of bioassay and structures of natural compounds. The control effects of active substances in TMV different host plants were determined. The systemic study results on antiviral activities of secondary substances from walnut leaves provide a new way for plant virus diseases control, and build a foundation for developing new botanical virucides.1 The study used the directed screening method for the first time. Secondary metabolites of 39 plants were extracted according to pretest results. Bioassays showed that ethanol extracts from different plants had different inhibition effect on TMV infection to Nicotiana glutinosa. The inhibitory rate of 8 plant extracts exceeded 90% among them. The plants are Nelumbo nucifera, Juglans regia, Ficus microcarpal, Myreca rubra, Diospyros kaki, Kyllinga breviforlia, Phyllanthus urinaria and Bauhinia varitagata. It indicated that plants containing alkaloid and flavonoids had higher antiviral activities. Considering their resources, distribution and collection difficulties. Nelumbo nucifera and Juglans rejia were selected as active plants for further study.2 The inhibitory rates of ethanol extracts from walnut leaves on TMV infection to Nicotiana glutinosa varied with concentration. Keep extract concentration at 10.00mg/mL, the results showed that the substances extracted by 70% ethanol had the highest inhibitory rate, which was 96.4% and it was 39.92% and 42.62% higher than that by 95% ethanol and 0.5% hydrochloric acidethanol mixture respectively. Bioassays indicated that substances extracted by solvents with different polarity from 70% ethanol extract had different inhibition rates on TMV infection to Nicotiana glutinosa. Among which the ethyl acetate extracts was highest. Stay the concentration at 1 .00mg/mL, the inhibitory rates in a decreaseing way were ethyl acetate extract, chloroform extract, aether extract, petroleum ether extract and n-butyl alcohol extract.The ethanol extracts from walnut leaves also had a strong contact toxiciry on Brevicoryne bressicae . The higher the concentration of extracts applied on aphids, the higher the knockdown rate was, and the shorter the median lethal time was. Six different extracts from the Walnut leaves were tested for antibacterial and antifungal activity. The extract of alcohol and acetic ester were found to have the remarkable bacteriostasis against 4 bacteria and a fungus (Rhizopus.sp) which were tested, and the higher the concentration, the larger the bacteriostasis. Different concentration of the alcohol extract made different Staphylococcus aureus, Bacillus subtilis and Rhizopus sp. bacteriostasis effect. The results also showed that the bacteriostasis on different bacterias were different at the same concentration.3 Active tracking method was adopted for the first time to isolate antiviral substances. Three antiviral flavonoids were isolated and purified from walnut leaves through solvent extraction, systemic solvent separation, column chromatography, thin layer chromatography and recrystalization. Their chemicalStructure were elucidated to be kaempferol, quercetin and hyperoside, by means of 'H-NMR, 13C-NMR, MS, IR, chemical reaction, and comparison with the spectral data of the known compounds. The study also indicated that the 3 flavonoids compounds all have antiviral activities. Meanwhile, September is proved to be the best time to collect leaves which is after walnut fruits were harvested.4 Different treatments have different control effect on tobacco mosaic disease. Inhibition rates of ethyl acetate extract decrease with dilution factor increased. Am...
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