Screening Of Insecticidal And Fungicidal Activities On 30 Species Chinese Herbal Medicines And Studies On The Insecticidal Ingredients Of Euonymus Japonicus

Although the utilization of plant materials to protect field crops and stored commodities against insect attack has a long history, botanical pesticide plays a minor role in modern pesticide industry. In fact, insecticidal plant has given great contribution to modern pesticide in another aspect. It's well known that many important pesticides, such as pyrethroids, carbamates and so on, were man-made pesticides designed according to the natural products. Chinese herbal medicine has been used in clinic over two thousands years, many of them exhibit pesticidal activities at the same time. It's an interesting research to find novel lead compounds from Chinese herbal medicine.In this paper, the insecticidal and fungicidal activities of 30 species Chinese herbal medicine have been investigated,herein all of tested plants were extracted by ethanol. The results showed that no obvious contact toxicities against the 3rd instars larvae of Mythimna separata Walker were observed in all treatment, and only the extract of Euonymus japonicus exhibited notable stomach toxicity. The contact toxicities against Myzus persicae and Tetranychus veinnensis were determined using the method of glass plate infusion (FAO 1980), no extracts performed potential value deserved to be investigated unfortunately. The inhibiting effects of extracts on mycelium growth against 4 species fungi, which includes Exerohilum turcicum, Botrytis cinerea, Bipolarris sorokiniana and Selerotinia scierotiorum, were measured. The results showed that several species plant exhibited moderate fungicidal activities against tested fungi, but Piper methysticum and Magnolia officinalis possessed excellent inhibition efficacy; The inhibiting spore germination test indicating a similar efficacy. In a conclusion, Piper methysticum and Magnolia officinalis were the potential candidates in the aspect of fungicide, but the further investigation was not included in this paper.Based on the results of bio-screening, Euonymus japonicus was preferred as the research object. Guided by the stomach toxicity test against 3rd instars larvae of Mythimna separata Walker, the active ingredients in Euonymus japonicus were investigated thoroughly. The bio-assay results showed that the active ingredients were located in the root bark and no activity was observed in other parts of plant. The extract was purified by macroporous adsorption resin, silica gel column chromatograph and pre-HPLC, ten compounds were obtained finally. By combining the related reference with the data of NMR and MS, the structures of ten compounds were elucidated. Z2 wasβ- sitosterol; Z3 was a new pentacycli triterpenoids compound, and this type compound was also first obtained from the plant; Compounds Z4～Z7 wereβ-dihydroagarofuran sesquiterpene polyesters, in which Z4 and Z5 were new compounds; Compounds Z8～Z11 wereβ-dihydroagarofuran sesquiterpene pyridine alkaloids, in which Z8^Z10 were first isolated from this plant.The toxicity of compounds Z4^Z11 against 3rd instars larvae of Mythimna separata Walker was investigated. The results showed that compounds Z5, Z7 and Z8^Z11 exhibited similar narcotic activity, there were also difference between them, symptom of the latter was irreversible, but revival was observed in low dosage treatments of Z4 and Z6. In contrast, insect in the treatment of compound Z4 and Z6 exhibited poison symptom. The LD50 of tested compounds Z4～Z11 were as 89.2,98.6,181.4,109.2,23.2,5.4, 5.3和4.7μg·g^-1, respectively.The cytotoxicity of compounds Z4^Z11 against Helicoverpa armigera ovary cell was measured by the method of MTT. The LC50 of tested compounds Z4～Z11 were as 42.19,27.16,104.62, 162.04, 36.37, 95.70, 37.49和91.92 mg·L^-1, respectively.