Study On The Correlation Between Active Substances In Walnut Kernels And Leaves And Soil Nutrients

Walnut(Juglans regia L.)is an important economic tree species in China,which has the effects of lowering blood sugar,antibacterial and repairing oxidative damage.In recent years,the medicinal and edible value of walnut has been continuously developed,but there are few studies on the reasons for the differences in activity caused by different environmental factors.Therefore,the study on the interaction between walnut active substances and environmental factors is helpful to the development and utilization of its value.In this study,the walnut cultivar ’ Xiangling ’ was used as the research object to explore the relationship between the antioxidant and hypoglycemic active substances of nucleolus and leaves and the characteristics of environmental factors such as soil basic characteristics,climate zone and temperature.The high-activity extracts in the leaves were identified by liquid-mass technology,and the mechanism of hypoglycemic effect of active substances and environmental factors was deeply explored.The results are as follows:(1)The contents of total phenols and total flavonoids and antioxidant activity in walnut leaves from different habitats were as follows: SZ>LW>HL.The contents of total phenols and total flavonoids and antioxidant activity in leaves of different tree ages were as follows: 1-10 years>10-20 years>more than 20 years.The total phenol,total flavonoid content and antioxidant activity of nucleolus showed the same trend as those of leaves,and the total phenol,total flavonoid content and antioxidant activity of nucleolus were lower than those of leaves under the same conditions.The leaves of 1-10 years old trees from different producing areas were selected for different polar organic solvent extraction.The total phenolic and total flavonoid contents of EAE were higher than those of other extracts.The EAE antioxidant capacity of SZ1 was comparable to that of VC,and different polar extracts had different degrees of hypoglycemic activity.The inhibitory activity of α-glucosidase and α-amylase was as follows: EAE>PEE>BAE>RAE.(2)A total of 22 polyphenols and 23 flavonoids were identified in the leaves of SZ1 by HPLC-MS /MS.A total of 21 polyphenols and 19 flavonoids were identified in the leaves of LW1.A total of 21 polyphenols and 22 flavonoids were identified in the leaves of HL1 by EAE.OPLS-DA was constructed to screen 16 different active substances such as ellagic acid,myricetin,catechin,(-)epigallocatechin,and quinic acid.The WGCNA model was constructed to screen out 17 active substances such as caffeic acid,ellagic acid and catechin.Based on the screening results of the two models,five key active substances:quercetin,2-hydroxycinnamic acid,catechin,naringenin and ellagic acid were selected for content determination.The contents of quercetin and ellagic acid were higher than those of the other three substances.The content range of quercetin was 766.69-1347.43 μg/g,and the content range of ellagic acid was 799.35-1422.45 μg/g.The contents of catechin,naringenin and 2-hydroxycinnamic acid were253.24-654.33 μg/g,440.49-885.20 μg/g and 242.52-963.22 μg/g,respectively.(3)Ellagic acid showed a significant positive correlation with total nitrogen,p H and total potassium(p<0.05),and a very significant positive correlation with total potassium(p<0.01).2-hydroxycinnamic acid showed a significant positive correlation with total phosphorus(p<0.05).Catechin and quercetin were positively correlated with total nitrogen and total potassium.Catechin showed a significant positive correlation with total nitrogen(p<0.05),and catechin showed a very significant positive correlation with total potassium(p<0.01).At the same time,catechin and quercetin were positively correlated with p H,total phosphorus and available phosphorus.Catechin was significantly positively correlated with p H and total phosphorus(p<0.01),and quercetin was significantly positively correlated with p H and total phosphorus(p<0.05).Polyphenols and flavonoids are greatly affected by climate types,and the average annual is.The effect of temperature on polyphenols and flavonoids is greater than that on polyphenols.(4)The results of hypoglycemic mechanism showed that the five key active substances could effectively inhibit α-glucosidase and α-amylase,and the inhibitory effect of quercetin and ellagic acid was better than that of the other key active substances.Quercetin and ellagic acid had reversible inhibition onα-glucosidase and α-amylase,and their inhibition types on α-glucosidase were mixed inhibition and non-competitive inhibition,respectively.Molecular simulation docking showed that quercetin and ellagic acid could form hydrogen bonds with amino acid residues in the active center of α-glucosidase andα-amylase,and interact with each other,thus reducing the binding with the substrate.The results of sucrose load in mice showed that quercetin and ellagic acid significantly reduced blood glucose levels in mice,and the effect was comparable to that of acarbose.In summary,this study found the accumulation factors and changes of quercetin,catechin,ellagic acid and other substances in walnut leaves from different producing areas,revealed the environmental factors affecting the accumulation of active substances in walnut leaves,and further studied the hypoglycemic mechanism of key active substances,which provided a theoretical basis for the development and utilization of antioxidant and hypoglycemic active substances in walnut.