Extract And Content Determination Of Toxicities Active Component Extracts From Portulaca Oleracea L. Against Cowpea Aphid

As the main pest of legume crops,aphid can transmit a variety of plant viruses when absorbing plant nutrients,which has a great influence on the yield of legume crops.Portulaca oleracea L.is widely distributed all over the country,and the whole plant can be used as medicine.Although it has been reported in many aspects of Chinese herbal medicine,there is still a lack of systematic research in pesticide pest control.In order to make full use of the wild plant resources,this experiment studied the extraction and separation methods of the toxic active components of Portulaca oleracea L.againgst cowpea aphid,and determined the content of the toxic active components,in order to provide a theoretical basis for the development of the plant insecticides based on Portulaca oleracea L.Main contributions of this work are as follows:1.Determination of extraction solvent for aphid killing active components of Portulaca oleracea L.（1）Several extracts of Portulaca oleracea L.had certain toxic effect on aphid,and the mortality increased with time.The order of aphid killing activity was:petroleum ether>ethanol>chloroform>ethyl acetate>water;48 hours later,at 0.05 level,there was no significant difference between ethanol and petroleum ether extracts,but there was significant difference with other solvents.（2）The petroleum ether and ethanol extract of=have higher toxic activity to aphid,and the mortality increased with time.LC₅₀ of petroleum ether=48.38mg（crude drug）/ml,and LC₅₀ of ethanol=45.79mg/ml.（3）HPLC analysis of different solvent extracts showed that the composition of chromatographic peaks was similar,but there were significant differences in the height of several peaks.There are many chemical components with strong polarity and weak polarity in ethanol extract.Compared with other solvents,70%ethanol has the best extraction effect.2.Comparison of aphid killing activities of different ethanol eluents from Portulaca oleracea L.（1）800 g Portulaca oleracea L.was used to prepare 9.86 g dry powder with different ethanol eluents,and the total yield was 1.23%.The quality of dry powder of each component was:20%ethanol 4.23g,the yield was 0.53%;40%ethanol 4.43g,the yield was 0.55%;60%ethanol 1.20g,the yield was 0.15%;80%alcohol did not get dry powder after freeze-drying.（2）Different ethanol eluents had certain toxic effect on aphid,and the mortality increased with time.LC₅₀ of the mixed component=0.75mg（dry powder）/ml,LC₅₀ of 40%ethanol=0.89mg（dry powder）/ml.The order of aphid killing activity was:mixture>40%ethanol>20%ethanol>60%ethanol.（3）HPLC analysis of different ethanol eluents showed that the composition of chromatographic peaks was similar,but there were significant differences in the height of several peaks.The chromatographic peak of 40%ethanol is significantly higher than that of the mixture,but its toxic activity is similar.It is speculated that the toxic activity of the mixture may be coordinated by a variety of substances.3.Determination of active components and correlation analysis of its insecticidal effect（1）Different ethanol eluents of Portulaca oleracea L.contain flavonoids,polyphenols and terpenes.（2）The flavonoid contents of 20%ethanol,40%ethanol,60%ethanol and mixed components were 19.48%,29.58%,9.78%and 22.57%,respectively.The contents of polyphenols were 19.81%,24.16%,11.03%and 23.06%,respectively.（3）The correlation coefficient between flavonoids content and aphid killing activity was 0.901.With the increase of flavonoid content,aphid killing activity was also enhanced.The correlation coefficient between polyphenol content and aphid killing activity was 0.947.With the increase of polyphenol content,aphid killing activity was also enhanced.The correlation coefficient between polyphenol content and aphid killing activity is higher than that of flavonoid content.It is speculated that the aphid killing active components include not only flavonoid but also some non flavonoid polyphenol components.