The Substance Basis Research Of Phenoloxidase Activity And Insecticidal Property Of Juglans Mandshurica Maxim

Juglans mandshurica Maxim belongs to the Juglans genus, which contains large amounts of phenolic compouds. There was not enough reports about its insecticidal active substance and related activity mechnism. In an effort to identify active ingredients with phenoloxidase activity and insecticidal properties in green walnut husk and walnut leaf, the following research was carried out.（1）As a promising target, we investigated phenoloxidase inhibitory activity and insecticidal effect aganist Plutella xyllostella L. and Aphis gossypii G. about green walnut husks extract of different month, different solvent and three main qunione compounds. The result of the phenoloxidase inhibitory activity showed July extract (IC₅₀=5.292 g·L^-1)<June extract (IC₅₀=6.947 g·L^-1)<August extract (IC₅₀=17.719 g·L^-1). The result of the insecticidal effect against Plutella xyllostella L. showed June extract (LC5o=0.840 g·L^-1)<July extract (LC₅₀=2.663 g·L^-1)<August extract (LC₅₀=5.858g·L^-1) after an artificial diet feeding 2d. June extract (LC₅₀=0.328 g·L^-1)<July extract (LC₅₀=1.386 g·L^-1)<August extract (LC₅₀=1.443 g·L^-1) after an artificial diet feeding 3d. The rule of phenoloxidase inhibitory activity is basically consistent with the insecticidal effect. On the other hand, the research of the insecticidal effect against Aphis gossypii G. gave a result as: July (LC₅₀=0.072 g·L^-1)<June (LC₅₀=0.296 g·L^-1)<August (LC₅₀=1.141g·L^-1) after an artificial diet feeding 24h. July (LC₅₀=0.022g·L^-1)<June (LC₅₀=0.190 g·L^-1)<August (LC₅₀=0.643g·L^-1) after an artificial diet feeding 36h. The rule of phenoloxidase inhibitory activity is also totally consistent with that of insecticidal effect, which indicated that green walnut husks had good insecticidal effect and the phenoloxidase can be used as a research target in the following research to identify the insecticidal active substance from green walnut husks.（2） For further confirm of the active ingredient and the feasible of phenoloxidase as research target, we investigated phenoloxidase inhibitory activity and insecticidal effect against Aphis gossypii G. of green walnut husks extract. The result of the phenoloxidase inhibitory activity showed petroleum ether extract (IC₅₀=4.414 g·L^-1)<chloroform extract (IC₅₀=7.025 g·L^-1)<n-butanol extract (IC₅₀=8.447 g·L^-1). As for the insecticidal effect against Aphis gossypii G., it was determined that petroleum ether extract (LC₅₀=0.005g·L^-1)< chloroform extract (LC₅₀=0.054g·L^-1)< n-butanol extract (LC₅₀=0.085 g·L^-1) after an artificial diet feeding 24h. Thus, the rule of phenoloxidase inhibitory activities is fully consistent with the insecticidal effect.（3） With the help of UPLC-MS methods, we analyzed the chemical constituents of three different solvent extract. On the basis of the differences of phenoloxidase inhibitory activity, the principal component analysis （PCA） and partial least squares（PLS） methods were used to explore the differences between the three groups and identify the metabolites. The results showed that three groups were completely different and the differences were mainly focused on secondary metabolites. In the currentl work,13 metabolites were identified, including four naphthoquinones, two flavonoids, one phenolic acid, four ester compounds and two other compounds. It was speculated that these different metabolites were closely related to insecticidal effect. These results would provide a valuable direction to develop new botanical insecticides.（4） Walnut leaf, the different part of Juglans mandshurica Maxim, showed a significant activation on phenoloxidase and insecticidal effect against Plutella xyllostella L. With the help of UPLC-MS method, we analyzed the composition of three different month extract. Based on the differences of phenoloxidase inhibitory activities, we used principal component analysis （PCA） and partial least squares（PLS） to explore the differences between the three groups and identified the metabolites. The result showed that three groups were quite different and the differences were mainly secondary metabolites. Currently, we found 24 kinds of metabolites and among them 18 species were identified, including nine naphthoquinones, two flavonoids, one ester compound and six other compounds. Combining the phenoloxidase activity and insecticidal property, it was considered that the metabolites were the potential active component against insect. These would contribute to providing a preferable insight to improve management strategies for insect.