| Euphorbia sieboldiana Morr.et Decne is one of the characteristics pesticides plants in Liu Panshan region in Ningxia province, which foot has been found having good anti-feeding activity on Pieris rapae. In order to clarify the chemical composition and determine the substances of insecticidal active ingredients, the research basing on the previous studies was driected by activity tracking, and focused on the extraction, isolation, identification and insecticidal activity of constituents from the foot of E.sieboldiana. Main results as follows:1.The insecticidal activities of the extraction fractions,which were obtained by socaking the foot of E.sieboldiana with 95% ethanol and then treated with petroleum ether, chloroform, ethyl acetate and butanol,against two kinds of pests of Pieris rapae and Plutella xylostella. were tested. All the extractions had the biological activity, but the petroleum and chloroform acetates possessed considerable activities to the testing pests. The dosage for test of all samples were 10.0 mg·mL-1, the anti-feeding activity of the extractives from petroleum ether and chloroform extracts shows better than others. The antifeedant rates of petroleum ether extracts against 5th-instar larvae of Pieris rapae during 24h,48h, and 72h was 93.12%, 86.67% and 77.50%respectively. The anti-feeding rates of chloroform extracts during 24h,48h, and 72h was 82.23% ,80.0% and 76.33%.And the antifeedant rates of petroleum ether extracts against 4th-instar of Plutella xylostella. during 24h,48h and 72h was 95.47%,93.65% and 94.73% respectively on the dosage. The antifeeding activity from the petroleum ether extractives is best on Plutella xylostella during 24h. The petroleum ether extractives showed better contact toxicity on Aphis sp during 24h and 48h and the corrected mortality was 88.78% and 87.10%.2.Active guiding method was applied to test, six substances (EP1～EP6), were isolated from the petroleum ether extractives by using TLC, normal pressure pillar chromatography and re-crystallization. Using IR, EI-MS,1H-NMR,13C-NMR, the molecular structure of the substances were identified that EP1:3-acetyl-2,6-dihydroxy-4-methoxybenzaldehyde; EP2:β-sitosterol; EP3:1-(2,4-dihydroxy-6-methoxy-3- methylphenyl)-ethanone; EP4:β-amyr-inacetate;EP5:octadecanyl-3 -methoxy-4-hydroxy -benzeneacrylate and EP6:octacosanol. 3.The six substances have been found to have biological activities to the Plutella xylostella L, Pieris rapae L.and Aphis sp. The results showed that three substances for testing have anti-feeding activity to some extent. The EP1 showed the best anti-feeding activity against the 4th-instar larvae of Plutella xylostella L. and the AFC50 was 0.8289 mg.ml-1 and 0.7081 mg.mL-1 during 24h and 48h, respectively. Following by EP3 with the AFC50 was 0.9621 mg.mL-1 and 0.7471 mg.mL-1. EP2 as P sitosterol has weaker anti-feeding activity against 4th instar larvae of Plutella xylostella L. and the AFC50 was 2.2089 mg.mL-1 and 1.6667 mg.mL-1 during 24h and 48h respectively. The results of the antifeedant rates were lower than the CK of rotenone. EP1,EP2,EP3 had toxic activities against 4th-instar larvae of Plutella xylostella L,and EP1 is bttter which the LC50 was 7.6093 mg.mL-1 against Plutella xylostella during 48h, the LC50 was 3.9886 mg.L-1 against Aphis sp during 48h.Comparing to two kinds of acetophenone, (3-sitosterol and the ethanol extract, petroleum ether extracts and fractions of each separation in the activity test showed that the activity is descence following by the isolated. So some other ingredients may exist in E. sieboldiana. or some other interplay action materials. So the further research on active imaterials and the interplay of which was very necessary. |
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