| The insect, Dendrolimus punctatus Walker contains not only high content of protein but also high content of functional polyunsaturated fatty acids. The development and utilization of polyunsaturated fatty acids from Dendrolimus punctatus will provide a new source of functional fatty acids, and can change the insect pest to a new bio-resource, which are of great research value. Because of D. punctatus has poison hair, the development of resources from D.punctatus is limited. Therefore, a simple and effective method removing toxin is studied, which is the base of development and utilization of the product related to D. punctatus. Based on the previous studies in our lab, the basic property and some pharmacological effects of D. punctatus toxins were studied and a method removing toxin's activity by simple heat treatment was obtained. Aslo the oil of D. punctatus removed toxin was extracted, its polyunsaturated fatty acid was preliminarily concentrated and the D. punctatus functional oil was obtained whose alpha linolenic acid's content was higher. The main results are as follows:The alcohol extract, water extract, ethyl acetate extract, acetic acid extract and phosphate buffer extract of the toxin from D. punctatus were detected by rabbit skin test. The results showed that the toxin could be more easily melted in alcohol and slightly melted in distilled water, but not melted in ethyl acetate, acetic acid and phosphate buffer. The main components of the toxin was not nonprotein, peptide, or alkaloids and amines. The toxin has good thermal stability at0-60℃, and it was completely inactivated at100℃.The antibacterial action of ethanol extract of the toxin from D. punctatus was tested by the filter papers. Bacteria inhibition test showed that ethanol extract of the toxin from D. punctatus had inhibition effect on bacterium, yeasts and fungi, Escherichia coli was stongly inhibited and Staphylococcus aureus was weakly inhibited.The optimum detoxifying method of the toxin from D. punctatus was purely heat treatment. With the temperature of heat treatment increasing, the activity of toxion decreased significantly. After the toxin was treated2h by heating to100℃, the irritative toxicity was't detected by rabbit skin test. The toxicological assessment of the D. punctatus sample treated2h by heating to100℃further was conducted through acute oral toxicity test, Ames test, micronucleus test of polychromatic erythrocytes in bone marrow and sperm shape abnormality test in mice. Its results showed that the acute oral LD50of powder from D. punctatus by heat treatment was greater than7500mg/kg-bw and the genetic toxicity test was negative. In our experimental context, the acute toxicity of powder from D. punctatus by heat treatment was classified as actually non-toxic grade as well as genetic toxicity was not found.Flash Extraction Technology was ultilized to prepare oil from D. punctatus whose toxin had been removed by heat treatment. The results of One-Factor experiments showed that different solvent density, different extraction time, different extraction voltage significantly influenced on fat extraction from D. punctatus whose toxin was removed by heat treatment. The optimum extraction conditions were as follow: solvent density1:50, extraction time1.5min, extraction voltage75v; Under this condition, the total yield of fat from D. punctatus was95.39%. The method for concentrating a-linolenic acid (ALA) ester from D. punctatus oil by complexing extraction with silver nitrate was further studied. The results showed that the complexing extraction optimum conditions of a-linolenic acid were as follows:the complexing medium of AgNO3concentration45%(the solvents40%menthanol-water) complexation temperature of0℃, complexation time1.5h and the content of a-linolenic acid was increased from15.32%of the crude oil to22.43%, increased by46.40%. These results will provide the technology basis for further optimizing the extraction technique of a-linolenic acid and preparing a-linolenic acid in a large scale. |
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