Screening Of25Species Of Shiwan Mountains Plants Of Antimicrobial And Herbicidal Activity

The methanol extracts of25species plant in15family in Shiwan Mountains were tested for inhibiting the growth of Ralstonia solaanacearum and Rhizoctonia solani respectively by resazurin assays, inhibitory zone assays and mycelial radial growth inhibition assays, and at the same time their herbicidal activity were tested by96-pore gelatin plate micro-screening assays; then searching out a suitable micro-screening method by optimizing the operation condition; finally, this study was dealing with the isolation,structures elucidation and biological activities of Cosmos sulphurens and Strychnos nux-vomica by activity-guided fractionation.1. The antimicrobial activities of the methanol extracts of25plants against Ralstonia solaanacearum were determined by resazurin micro-screening assays. Results indicated that, to a certain degree, most of the methanol extracts exhibited positive action against target microorganisms. Especially the extracts of10kind of plant such as Blumea aromatica, Flemingia prostrata, Maclura cochinchinensis, Asarum longe rhizom atosum, Strychnos nux-vomica, Cosmos sulphurens, Illicium difengpi, Hedyotis diffusa, Illigera rhodantha and Plumbago zeylanica show the significant bioactivities.Among these, the MIC of B.aromatica, F.prostrata, M.cochinchinensis, A.longerhizomatosum, S. nux-vomica, C.sulphurens are0.50、0.75、1.00、3.00、4.00、8.00mg/ml respectively. The result of inhibitory zone assays also show that the antimicrobial activity of B. aromatica, F.prostrata, H.diffusa, S.nux-vomica S.subprostrata, M.cochinchinensis was significant, and among this, the extracts of B.aromatica and F.prostrata exhibited most potent activities against R.solaanacearum with the diameter of inhibiting bacteria circle were1.38,1.33cm respectively at the concentration of300mg/ml. The results of further testing of antifungal activities of10species antibacterial activity plants above also showed that the extracts of A. longerhizomatosum, I. difengpi, S. nux-vomica, C. sulphurens exhibited the most significant activities against R.solani with their EC50were0.93,0.64,1.18,1.99mg/ml at the concentration of3mg/ml. When Pennisetum alopecuroides, Beta vulgaris and Raphanus sativus used as target plants, the result of96-pore gelatin plate micro-screening assays showed that the methonal extracts of S. nux-vomica and C. sulphurens exhibited significant herbicidal activity.2. R.solaanacearum used as target bacteria, comparing the results of antimicrobal activity between resazurin assays and inhibitory zone assays. The results showed that resazurin micro-screening assays would increase screening efficiency and decrease omission. Using plant seeds metioned above as target organism, the optimized conditions of96-pore gelatin plate micro-screening assays for detecting herbicidal activity of plants extracts were estabished. This study considering four factors of conditions, such as the sorts and amounts of solvent, soaking time, adding method and active evaluation index. The experiment results shows the optimized conditon were that the sorts and amounts of solvent was methanol with the concentration of2%-4%, soaking time was12h, adding method was taking medicine agar method with the seedling height inhibitiory rate as active evaluation index. Experiment exhibits that micro-screening assays method proved to be intuitionistic, reliable, fast, sensitive, microscale and economic.3. S. nux-vomica and C. sulphurens were respectively isolated and purificated by means of silica gel CC, ODS and Sephadex LH-20. Six high-purity compounds were isolated from S. nux-vomica and on the basis of spectral data, two of them were identified as strychnine and archen while15ingredient were isolated from C. sulphurens, their structure was to be identified.In conclusion, this study proved that resazurin micro-screening assays would increase screening efficiency and decrease the omission of crude extracts by comparing with inhibitory zone assays; Established a herbicidal activity screening mode which based on96-pore gelatin plate micro-screening assays and screened out several kinds of plants species, reported their antibacterial, antifungus and herbicidal activity against bacteria, fungus, and weeds mentioned above respectively for the first time in domestic; Besides,21compand with2identificated were obtained from S. nux-vomica and C. sulphurens. All in all, this paper provided a fast and microscale screening technique for the comprehensive evaluation of the activity of plant extracts and the study also provided a scientific basis for utilization enormous plants of Guangxi in development of botanical pesticide and also provided a reference for searching for better lead compounds for the R&D of new pesticide.