Study On The Mechanisms Of Flavonoids From Actinidia Arguta On Reducing Of Uric Acid

Actinidia arguta is the "king of precious fruits" with a unique flavor,and has great potential as a "food drug homology" functional food.Flavonoids are one of the main active ingredients in Actinidia arguta.However,there is currently limited understanding of the types and physiological functions of flavonoids in Actinidia arguta,which limits the effective development and utilization of this characteristic "food drug homology" resource.In response to the issue of unclear types and physiological functions of flavonoids in Actinidia arguta,In this study,we identified the types of flavonoids in Actinidia arguta and studied their effects on uric acid and kidney protection functions and mechanisms based on a mouse model.The main research findings are as follows.1.In order to clarify the types,content,and differences among varieties of flavonoids in Actinidia arguta,this study compared and analyzed the flavonoids in the fruit of two main cultivated varieties in northern China,"Qssg" and "Lc".A total of 118 flavonoids were identified in these two varieties,mainly including 64 flavonols,18 flavonoids,and 12 flavanols.The total flavonoid content of variety "Qssg" is 1.13 times than that of "Lc",and there is a significant difference in flavonoid content and types between the two varieties.Through separation,purification,and use of nuclear magnetic resonance technology,12 flavonoid compounds were identified from Qssg.The discovery of isoflavones-daidzein in Actinidia arguta provides a new source of isoflavones for human diet.2.In order to detect the physiological activity of Actinidia arguta flavonoids in reducing uric acid,based on a mouse model,this study analyzed the effects of low(62.5 mg/kg),medium(125 mg/kg),and high(250 mg/kg)concentrations of Actinidia arguta flavonoids on various physiological indicators in high uric acid mice.The results showed that all three concentrations of Actinidia arguta flavonoids significantly reduced uric acid(UA)(P<0.05),urea nitrogen(BUN)(P<0.05),creatinine(Cr)(P<0.05),3-phosphate glyceraldehyde dehydrogenase(GAPDH)(P<0.01),and elevated liver glycogen(P<0.01)indicators.The low concentration group had a better uric acid lowering effect than the medium and high concentration groups.The flavonoid of Actinidia arguta showed strong inhibitory activity of xanthine oxidase(XOD)and adenosine deaminase(ADA)in vitro and XOD in liver in vivo,which indicated that it inhibited the kinetic enzyme of uric acid metabolism to control the metabolism of purines to produce uric acid.3.In order to detect the effects of Actinidia arguta flavonoids on intestinal microorganisms and metabolites in hyperuricemic mice,16 S r RNA sequencing and metabonomics were used for joint analysis.The results showed that the flavonoids of Actinidia arguta restored the abundance and quantity of intestinal microbiota in hyperuricemic mice to a certain extent.The detection of intestinal metabolites found that docosatetraenoic acid,docosahexaenoic acid and eicosanoic acid in fatty acids were down regulated in the HUA group,and arachidonic acid was up regulated in the flavonoid group.Dibutyl phthalate in phenolic acids was down regulated in HUA group,while in the flavonoid group,the contents of quinic acid,xanthohumol,thymol,2-Methoxy-4-propylbenzoic acid were reversed and the amino acid imbalance of 3-indole-Lvaline,N-cinnamoylglycine,N-crotonylglycine,and N-acetyl-L-aspartate was restored.The correlation between intestinal metabolites and intestinal microbiota showed that the flavonoids of Actinidia arguta induced the Oscillibacter to produce the tetrahydropalmatine,an alkaloid,in the intestinal tract of mice with hyperuricemia,which have a good effect on reducing UA.Western blot analysis showed that the flavonoids of Actinidia arguta decreased the expression of uric acid reabsorption protein GLUT9 and URAT1,and increased the expression of uric acid excretion protein OAT1 and ABCG2.4.The flavonoids of Actinidia arguta can induce the increase of the activities of superoxide dismutase(SOD),glutathione peroxidase(GSH-PX)and catalase(CAT)in the kidney of mice,reduce the content of malondialdehyde(MDA)in the kidney,thus alleviating the degree of pathological damage in the kidney of mice.It was found that the flavonoids of Actinidia arguta had scavenging effects on DPPH free radicals,superoxide anion free radicals and hydroxyl radical,and significantly reduced the level of reactive oxygen species(ROS).Western blot analysis showed that the flavonoids from Actinidia arguta alleviated the activation intensity of NLRP3,weakened the interaction between NLRP3 and apoptosis-related spot like protein(ASC),inactivated caspase-1,and effectively reduced IL-1β by reducing oxidative stress and promoting the inactivation of inflammasomes.This indicates that Actinidia arguta flavonoids have a certain alleviating and protective effect on inflammation in the kidneys of mice,thereby promoting uric acid excretion.5.To verify the protective effect of Actinidia arguta flavonoids on the kidneys,this study investigated the effects of kiwifruit flavonoids on four important metabolic pathways in the kidneys.Analysis of renal metabolite enrichment pathways showed that Actinidia arguta flavonoids caused a downregulation of adenine and cytidine 5 ′-cytidine content,without causing renal inflammation;It can restore the imbalance of amino acids in the kidney of hyperuricemic mice,including the levels of pyroglutamate,L-isovalerylglycine,ornithine,carboxyethylarginine,N-acetyl-L-glutamic acid,etc;It also can induce upregulation of amygdaline,dihydrocapsaicin,and deoxaconitine;Resulting in a significant upregulation of phenolic compounds such as perilla alcohol,cinnamic alcohol,shark acid,and 2-hydroxy-6-pentadecylbenzoic acid.Actinidia arguta flavonoids maintain kidney health and indirectly promote uric acid excretion by affecting four metabolic pathways.To sum up,the flavonoids of Actinidia arguta induced the Oscillibacter to produce the tetrahydropalmatine,an alkaloid,in the intestinal tract of hyperuricemic mice,inhibited key enzymes in uric acid synthesis,regulated intestinal microbiota,affected the expression of uric acid transporters,and regulated four metabolic pathways in the kidneys to achieve uric acid lowering effect.The experiments in the study verified the inhibitory activity of xanthine oxidase and adenosine deaminase of tetrahydropalmatine,and found that the flavonoids of Actinidia arguta can affect the expression of uric acid transporter.Tetrahydropalmatine is likely another evidence that gut microbiota metabolites regulate host uric acid metabolism.The results of this study provide a theoretical basis for the development and utilization of the flavonoids in Actinidia arguta.