The Studies On The Extraction, Isolation, Purification, Identification And Aphid-killing Mechanism Of The Active Aphid-killing Substances From Eupatorium Adenophorum

Major: Genetics Candidate for Ph. D. Wang Yiding Tutor Professor Liu ShiguiIn this paper, the toxicity of Eupatorium adenophorum (Spreng.) to the cotton aphid (Aphis gossypii Glover) was evaluated in laboratory. In a laboratory study the total ethanol extract from E. adenophorum is highly effective against the aphids. The LC50 of the total ethanol extract against apterous adult aphids is 167. 9mg/L, 48 hours after treatment by dipping method. Hexane extract, chloroform extract, ethyl acetate extract and ethanol extract were got from the total ethanol extract in proper order. The corrected mortality of aphids treated with the chloroform extract of different concentrations is higher than that of aphids treated with other 3 kinds of extracts at same concentrations. It is thought that E. adenophorum contains a few kinds of aphid-killing substances. By means of the techniques of systematic extraction, thin layer chromatography and GC-MS,an active aphid-killing substance named Eupatorin A was separated out of the chloroform extract and purified at the first time. Its chemical name is 1'H-Androst-16-eno[16, 17-b] indol-3-ol, 1-methyl-, (3. beta., 5. alpha.), its chemical formular is C26H35NO. Its molecular weight is 377. Eupatorin A at a concentration of 2g/L can kill 81. 3% of the cotton aphids. Its LC50 against cotton aphids is 362. 8mg/L. Tests also showed that Eupatorin A can inhibit the activity of AchE and Na-K-ATPase of the cotton aphids in vitro and in vivo. The inhibition was deepened with the bigger concentration of Eupatorin A and the longer toxic time. 48 hours after the aphids were treated with Eupatorin A at a concentration of 2g/L, the activity of AchE and Na-K-ATPase of the cotton aphids was only 30.3% and 21.6% of that of the contrast respectively. These could be the deaths of cotton aphids. When at a concentration of 2g/L, Eupatorin A can inhibit the activity of carboxylesterase of the aphids. This showed that Eupatorin A can not only kill the aphids but also be used as a synergist to achieve better pest-killing effectiveness. The security experiments have showed Eupatorin A is less toxic and safe for environment organism.