Screening Of Plant Pathogen Inhibition Of Plant Extracts

It has an important scientific sense to find substances of antibacterial activities from natural plant resources and explore deeply its biological activities. Here are abundant natural antibacterial plant resources which are ideal material sources of biocide with low toxicity, no residue, high efficiency, low cost and so on. In this study,77 species of endemic plants from Yunnan were selected, most of which had less reported. The model of active screening of 12 plant pathogenics was made, and further study on separation, purification and structural identification of Eleutherrine plicata extracts had been done.Twelve kinds of plant pathogens including Pyricularia grisea, Fusarium moniliforme, Exserohilum turcicum were used as tested strains. Antifungal activities of 77 plant extracts at the concentration of 200μg/mL were tested against P. grisea, F. moniliforme, E. turcicum, etc. with the method of growth rate. The result showed that 15 plant extracts had inhibition effect on the mycelia growth. Extracts from Alpinia chinensis, Pycnarrhena poilanei, Agave americana, Eleutherrine plicata, Gonioth alamusgriffithii, Sarcandra hainanensis had more than 50% inhibition rate against the mycelia growth to at least one pathogens, and 8 extracts from Vatica xishuangbannensis, Morindu cochinchinensis, Alpinia chinensis, etc. had inhibition rate against the growth to at least 3 pathogens. Compared with the positive control, Eleutherrine plicata, Sarcandra hainanensis, Agave americana, etc. had more stronger inhibition effect. Therefore, under the same conditions, distinct differences existed in antibacterial activity of different plant extracts to pathogens.Primary studies on separation of methyl alcohol extracts of Eleutherrine plicata had been done. Silica gel column chromatography, crystallization and High Performance Liquid Chromatography were used to separate, spectrum analysises were used to identify the structures. The results showed that ethyl acetate fraction has strong antibacterial activity, separation of the ethyl acetate fraction and activity determination was performed, and a stream had been obtained.Antifungal activities were tested against Colletotrichum liliacearum with growth rate method. Through spectrum analysis,1HNMR,13C-NMR and MS were used to analyze its structure. Compound a (crystalline D-1) was isoeleutherol, and it did not show the obvious activity with a EC50 (284.91μg/mL). The reason needs further analysis and more researches.