Studies On Antiviral Components Of Botanical Pesticides VFB And Screening Of Some Plants For The Anti-TMV Activity

Direct selection of anti-viral compounds from plants is an important approach in novelantiviral agents development. To provide new materials and theoretical basis for exploitationof antiviral agents from plant resource, this research has been conducted mainly on thefollowing three aspects: the active ingredients were isolated from the botanical antiviral agentVFB by bioassay-guided fractionation modern separation technology, and identifiedpredominantly on the basis of nuclear magnetic resonance(NMR) data; the ethanol extracts of313plants(belonging to214plant species of74families)growing in the northwestern Chinawere evaluated by local lesion and leaf-disc methods to see whether the plants are with orwithout anti-TMV activity; Extracts of the plants screened out were used as experimentalmaterial for preliminary study of the synergistic effect to VFB. The main results andconclusions are shown as follows:1.15compounds were isolated from the botanical antiviral agent VFB based onbioassay-guided fractionation, and the chemical structures of12compounds were identifiedby comparison of their MS and NMR data with those reported in the literature. Thosechemicals include Methyl gallate, β-Sitosterol,7-methoxycoumarin, β-Amyrin, Emodin,Liquiritigenin, Ursolic Acid, Arctiin,4-[(2S,3R,4S)-4-[(S)-(3,4-dimethoxyphenyl)hydroxymethyl]tetrahydro-3-(hydroxymethyl)-2-furanyl]-2-methoxyphenyl, Quercetin,5-(3′,4′-dimethoxyphenyl)-3-(β-(3′,4′-dimethoxyphenyl)-α-hydroxyl)-2Hfuran-4-hydroxy-4methyl-β-D-glucopyranoside and2-oxo-3-(3',4'-dihydroxyphenylethyl)-5H-furan-4-(4'-p-methoxyphenylethyl-3'-O-α-L-rhamnylpyranylosyl (1-2)-β-D-glucopyranoside. Chemicalstructures of the remaining3compounds needed further confirmation.2. The anti-tobacco mosaic virus (TMV) activity of15compounds was tested by locallesion and leaf-disc methods, and the results indicated that the glycyrrhizin and ursolic acidshowed a significant inhibitory activity against TMV on different host species at aconcentration of1mg/mL. Those two compounds could strongly inactivate TMV in vitro, andthe inhibition rate of necrotic local lesions could reach54.20%and41.00%, respectively; theyalso had a good preventive effect on TMV infection to N. glutinosa, and the preventive effect rates were48.52%and45.73%, respectively; and they also showed certain activities ininhibiting multiplication of the TMV with inhibition rates of more than33.00%. It can beconcluded that the glycyrrhizin and ursolic acid were main antiviral compounds of VFB.3. The anti tobacco mosaic virus (TMV) activity of95%ethanol extracts from313plantswere screened by the half-leaf method.54plant samples belonging to48plant species of27families showed a significant inhibitory activity against TMV in vitro, with inhibition rates ofmore than50%. Based on the result, the activity of54plant extract on infection andreplication was further determined by the whole-leaf and leaf-disc methods. Among them,extracts from six species [Rhodiola eurycarpa (Frod.) S. H. Fu, Abelia chinensis R. Br.,Cephalotaxus sinensis (Rehder et E. H. Wilson) H. L. Li, Cynanchum komarovii Al.,Ailanthus altissima (Mill.) Swingle and Polyporus mylittae Cook.et Mass] predominantlyinhibited both infection and viral replication with inhibition rates of over50%, which neededto be further studied.4. In terms of synergistic effect to VFB, the preliminary study of six plants′extracts[Rhodiola eurycarpa (Frod.) S. H. Fu, Abelia chinensis R. Br., Cephalotaxus sinensis (Rehderet E. H. Wilson) H. L. Li, Cynanchum komarovii Al., Ailanthus altissima (Mill.) Swingle andPolyporus mylittae Cook.et Mass] indicated that extract of Polyporus mylittae Cook.et Massshowed an significant synergistic activity to VFB.Abundant plants having anti-viral activity widely exist in nature. The types of secondarymetabolism products produced by those plants are plentiful and the structures of theseproducts are usually unique. Furthermore, complicated interactions between different plantshave been found through researches. Therefore, plants are the best natural resources to findnew and environmentally friendly anti-viral agents and compounds with low toxicity, lowresidue and high efficiency. It has both practical and theoretical significance in the rationaldevelopment and utilization of natural plant resources in China, as well as in the developmentof independent intellectual property rights of pesticides.