Extraction And Insecticidal Activity Of Pyrrolizidine Alkaloids From Lithospermum Erythrorhizon

In the historical process of pesticide development,botanical pesticides have always been the focus of people's research.Insecticidal substances isolated from plants have been applied to pesticides for a long time.Most of these plants are medicinal plants with many pharmacological activities,which not only cure diseases,but also have certain toxicity.As the birthplace of Traditional Chinese Medicine,China has about 12,000 kinds of medicinal plants,many of which have insecticidal activity.Therefore,the extraction of insecticidal substances from Traditional Chinese Medicine has become a direction of pesticide research.Lithospermum erythrorhizon Sieb.et Zucc..as a Traditional Chinese Medicine containing alkaloid,have no experiment on insecticidal activity.However,its potential insecticidal activity is worthy of our in-depth study,which will also provide a new direction for the development of botanical pesticides.In this thesis,the extraction solvent of total alkaloids from Lithospermum erythrorhizon was optimized.The antifeedant activity and contact activity of Lithospermum erythrorhizon total alkaloids extract of Spodoptera exigua were evaluated.The components with insecticidal activity in total alkaloids were separated and purified by chromatography and thin-layer chromatography.The main results were as follows:1.The extraction rate of total alkaloids was taken as the index,and the total alkaloids from Lithospermum erythrorhizon were extracted by acid extraction and alkali precipitation.Alkaloids were extracted by different acid-alkali solvent combinations,and the highest extraction rate was determined to be hydrochloric acid-sodium hydroxide combination.2.Taking Spodoptera exigua as the test pest to research insecticidal activity of Lithospermum erythrorhizon total alkaloids.The results showed that the total alkaloids extracted by different solvents had contact activity to Spodoptera exigua,and the activity gradually increased with the increase of concentration and time.The total alkaloids extracted by different extraction solvents have obvious antifeedant activityto Spodoptera exigua.The higher concentration,the stronger activity.However,the antifeedant activity was obvious,and the contact activity was relatively weak.3.Three alkaloids(alkaloid 1,alkaloid 2,alkaloid 3)were isolated and purified from Lithospermum erythrorhizon total alkaloids by chromatography and thin-layer chromatography.The insecticidal activity of pyrrolizine alkaloids in Lithospermum erythrorhizon has been preliminary confirmed.