Extraction And Separation Of Insecticidal Substances From Leptopus Chinensis And Effects On Several Enzymes

The root of Leptopus Chinensis(Bunge) Pojark, belonging to Euphorbiaceae, was extracted with petroleum ether, chloroform and methyl alcohol by different methods. Insecticidal activitives of crude extracts and fractions against Plutella xylostella were tested, and its effects on activities of several enzymes from the pest were evaluated. 1.The results indicated that Sohxlet was the most effective extraction method, the extract rate with methyl alcohol was about 21.83%, and that of warm soaking and cold soaking were 15.45%,19.45% respectively. With the same extraction methods, the extract rate of methyl alcohol was the highest, the second was chloroform, and petroleum ether was the lowest. 2.Results of antifeeding experiments showed that chloroform extract possessed the strongest antifeeding activities against the pest, whether in no-choice or in choice tests. The AFC50 was 14.64mg/mL 24 hours after treatment in no-choice tests, but AFC50 values of petroleum ether and methyl alcohol extracts were 32.45mg/mL, 21.73mg/mL, respectively. Results of inhibition effectiveness to the growth and development of pest indicated that chloroform extract had stronger inhibiting activities than the other two extracts. The inhibition rate was 36.17% at the concentration 10mg/mL after 4 days treatment;In the stomach poison tests, both petroleum ether and chloroform extracts had better bioactivities, the corrected morality of them at 48 hours after treatment were 14.69%, 14.17%, respectively. But the contact poison effectivrness of all three extracts were low. The methyl alcohol extract had a certain oviposition deterrence activity against Plutella xylostella adults, but the other two extracts didn't have. 3.The chloroform extract was selected to separate and purify in the experiment. The sequences of extract rate were NCEW>CEW>CEB>NCEB by partition in liquid extraction method. The NCEB fraction was identified to be the most active as detected by bioactivities, which antifeeding rate was 86.5% at the concentration 10mg/mL after 24 hours treatment. Thin layer chromatography (TLC) analysis was used to research the suitable constitutes and proportion of spread solvent, which can separate NCEB. The results indicated that the...