Bio-Activities Of The Extracts From The Stem And Leaves Of Lycopersion Esculentum Mill Against Lipaphis Erysimi Kaltenbach And Isolation, Purification And Structure Identification Of The Active Substances

Bio-activity of different tissues extracts from 24 plants against Lipaphis erysimi Kaltenbach were tested. The results showed that at the concentration of 40mg/mL, the extracts of Lycopersicones culentum, Macleaya cordata, Polygonum multiflorum, Rumex japonicus, Pinus massoniana and Zingiber officinale Rosc from Yunnan had good activities of 92.9%,79.4%,74.5%,68.6%,60.2% and 57.8%, respectively. According to the high insecticidal efficacy, L.culentum was selected to be further investigated for active ingredients. We had done the indoor control experiment of L. esculentum extracts against L.erysimi at different concentrations and also the field pot trail. Concentration gradient test showed that the concentration of extracts had positive correlation with its insecticidal efficacy. Field plot trial showed that at the concentration of 30mg/mL, the control effect of L. esculentum extracts against L.erysimi reached 97%.This effecthave no significant differences with imidacloprid at the concentration of 1.33mg/mL.The ethanol extract from stem and leaf of L.culentum was preliminarily separated into four parts by liquid-liquid extraction with petroleum ether, ethylacetate, n-butanol. The lethal activities of four parts by liquid-liquid extraction against L.erysimi were determined by pot experiment in the culturing room. The results showed that at the concentration of 20mg/ml, the activity of petroleum ether and ethylacetate fractions against L. erysimi was much higher than that of the others,its corrected mortality rate was 98.3% after 24 hours; the corrected mortality rate of n-butanol fraction was 45.9% after 24 hours,the water fraction had few insecticidal activity, the corrected mortality rate was 7.3% after 24 hours. Then we select petroleum ether fraction to do the concentration gradient test.Results showed that the concentration had positive correlation with its insecticidal effect.The LC50 of petroleum ether fraction is 6.3mg/mL which is below the crude extracts'. This result showed that petroleum ether fraction enriched the active ingredient.By silica gel column chromatograghy and tested by TLC analysis, will the same or similar componets merger, the extract was separated into 6 fractions. The activity of fraction 2 had the stronger activity with the corrected mortality rate of 96.5% at the concentration of 10mg/ml after 24 hours. Fraction 2 was further separated by silica gel Column Chromatography (CC), the gel Chromatography (Sephadex LH-20). One purified compound named LH1 with insecticidal activities (corrected mortality of 78.6% after 24 hours) was obtained. The spectra data of 1H-NMR, 13C-NMR were used to detect the structure of this compound. Although the structure was not identificated, some important data was obtained. This active compound may contain hydrogens of ENE key and even oxygen carbon. The MS spectra showed that its molecular weight was 300.1415. The active compounds were extracted, isolated and purified, as an ester of fatty acid. These experiment results will establish a base to developing a new phytochemical pesticide against L.erysimi in the future.