Studies On The Purification, Extraction And Control Of Sitophilus Zeamais Motschulsky From Azadirachtin A

Azadirachtin, the most potent insect antifeedant, repellance and growth-regulating agent, is a kind of tetranortriterpenoids extracted from the seed of the neem tree, azadirachta indica A.Juss. Studies revealed that the azadirachtin-based pesticides showed high efficiency in pest control, no effect on the natural enemies, less damage to the environment, low toxicity to mammals and the human beings, which make it a promising alternative to the synthesized pesticides. At present, extensive researches have focused on the extraction of effective ingredients, structural determination and favorable application of azadirachtin. The method to extract azadirachtin is mostly traditional solvent extraction(TSE). However there are few reports on CO2 supercritical fluid extraction(SCF), on the components of the SCF extracts and on the biological activeness of the main ingredients after extraction. In this thesis, we have systemly studied on the analyses with high performance liquid chromatography(HPLC), the method of the isolation and purification, the biological activity against adults of Sitophilus zeamais Motschulsky of azadirachtin. Then we established a process of neem industrialization, identified the main components of fatty acids in neem oil, and offered a possible way to control stored-product insect pests. The main conclusions are as follows.1.Established a method of the isolation and purification of azadirachtin A with the flash column system of silica gel and thin layer chromatography(TLC). The 5 pure fractions were analyzed by UV-vision chromatography and high performance liquid chromatography(HPLC), and we got azadirachtin A 95% pure.2.The neem oil was analyzed using GC-MS, the fatty acids extracted with TSE have the same components with SFE. The main components were determined as 8-octadecenoic acid 51.15%, octadecanoic acid 19.13%, hexadecanoic acid 16.78%, 7,10-octadecadienoic acid 9.86%, eicosanoic acid 1.24%. And other under 1% fatty acids such as cis-3-octyl-oxirane octanoic acid, docosanoic acid, 9-octadecenoic acid, 11-eicosenoic acid, 9-hexadecenoic acid and heptadecanoic acid.3.The reversed-phase HPLC method is used to measure the quantitative analysis of azadirchtin A in neem crude extracts. The extracts were analyzed on column C18(3.9mm×150mm), at room temperature, using acetonitrile-water(30:70 by volume) system with 1.0mL/min as the mobile phase, and detected at 215nm.4.The technique was studied to extract azadirachtin A from neem kernels. Uniform...