Antiviral Activity And Mechanism Of Anti-viral Constitutents Against TMV From Rostellularia Procumbens

Rostellularia procumbens is used in Chinese traditional medicine as a bitter aromatic drug and in treatment of colds and gastric diseases.Using local lesion and leaf discs assay, extracts from Rostellularia procumbens were screened for antiviral activity and mechanism against Tobacco mosaic virus (TMV). Base on the research of Rostellularia procumbens bioactivity, we isolate its chemical constituent and identify structure. The main results were as follows:1. Rostellularia procumbens were evaluated for not only the antiviral effect on virus infection and replication, but also the therapeutic effect on tobacco mosaic disease caused by TMV. The results showed that Rostellularia procumbens could significantly inactivate TMV in vitro assay. When tested at a concentration of 1mg/mL, the extracts produced only 70% inhibition of virus. Determination of the inhibition of TMV replication with leaf-discs method demonstrated that Rostellularia procumbens had a high inhibitory activity against TMV replication in leaf discs of Nicotiana tabacum CV., K₃₂₆. Within 8 hours after inoculation, extracts from Rostellularia procumbens suppressed virus replication was determined with different concentration. When tested at a concentration of 1mg/mL after inoculate 48 hours,the inhibitory rate of Rostellularia procumbens was high on 94.8%. The experimental results in greenhouse indicated that the extracts from Rostellularia procumbens had some certain therapeutic effect on tobacco mosaic disease caused by TMV in tobacco plant. The results of real-time PCR demonstrated that the extracts could strongly inhibit the expression of RdRp and CP gene. When tested at a concentration of 1mg/mL, the expression levels of RdRp and CP gene were respectively degrade 66.04% and 61.92%.Thus reduce the TMV-RNA content in the host.2. The extracts from Rostellularia procumbens didn't have direct viricidal effect on morphous and structure of TMV particles, while they showed strong activity by affect the antigenic determinant of TMV coat protein and combine with it in vitro. After that, the TMV particles was deactivated and the recognition potentia with host infextation sites was degraded also.By determining the content of MDA, chlorophyll and the activity of the defendant enzymes including POD, PPO, SOD and PAL. By observing the changes of Isoezyme and PR spectra, it was found that extracts from Rostellularia procumbens could induce resistance to TMV in the host to some extent, products some new PR spectra which we didn't find in Positive control (diseased leaf) and negative control(healthy leaf) , increase inhibitory activity of host against virus infection.3. In the study, active constituents from Rostellularia procumbens were isolated and purified through solvent extraction, systemic solvent separation, silica gel column chromatography and high performance liquid chromatography. We got five purified compounds at all.Their structure and bioactivity were also studied by spectroscopy method, and they show certern antiviral activity.