The Studies On Fermented Noni(Morinda Citrifolia L.) Juice In Improving Insulin Resistance Based On The Nrf2/ARE Pathway And Its Active Compounds

Morinda citrifolia L.,commonly known as Noni,is a Morinda plant belonging to the Rubiaceae family.It grows widely in tropical and subtropical regions,and is mainly distributed in Hainan,Paracel and Taiwan islands in China.Noni juice is a fermented juice produced by natural fermentation of Noni fruit,which contains a variety of active compounds such as phenylpropanoids,flavonoids,glycosides,terpenes.Fermented Noni juice,as a natural new resource food,can significantly prevent and improve insulin resistance,which is a pathological feature of type 2diabetes mellitus(T2DM).However,the current research on the improvement of insulin resistance by Noni juice mainly focuses on the detection of routine blood biochemical indicators such as blood glucose,blood lipids and insulin,and the underlying mechanism and active substances that exert its efficacy have not yet been elucidated.Therefore,it is of great significance to reveal the molecular mechanism of fermented Noni juice to improve insulin resistance,and explore its active components.This study combined in vitro and in vivo experiments to explore the regulatory effect of fermented Noni juice on insulin resistance and blood glucose homeostasis in Hep G2 cells and spontaneous T2DM db/db mice based on the Nrf2/ARE pathway(Nrf2/HO-1/JNK/IRS1/PI3K/AKT/GLUT4).Further,the active compounds were isolated and purified from effective extraction parts of fermented Noni juice,and the molecular mechanism of active compounds to improve insulin resistance was elucidated.1.In vitro,fermented Noni juice significantly promoted glucose uptake and consumption in insulin-resistant Hep G2 cells,and improved intracellular and extracellular glucose imbalance and insulin resistance.Also,it relieved the oxidative stress state of Hep G2 cells by regulating the antioxidant defense system.Mechanistic studies found that fermented Noni juice could significantly up-regulate the expression of key proteins and genes in the Nrf2/ARE signaling pathway.2.In vivo,fermented Noni juice significantly improved blood glucose homeostasis,glucose tolerance,and insulin tolerance in db/db mice.Meanwhile,it also promoted insulin secretion and relieved oxidative stress.Furthermore,it reversed the histopathological damage to mouse liver tissue caused by T2DM and repaired the abnormal morphology and structure of liver cells.In addition,fermented Noni juice also significantly promoted the expression of Nrf2/ARE pathway-related proteins and genes in the liver tissue of db/db mice.3.It is preliminarily clarified that ethyl acetate part and water part are active extraction parts of fermented Noni juice.Under the guidance of activity,chromatographic separation techniques such as silica gel column chromatography,gel column chromatography and high performance liquid chromatography were used to track and separate chemical components in the active extraction parts,and seven compounds(Compounds 1-7)were identified by comprehensive use of infrared spectroscopy,mass spectrometry and nuclear magnetic resonance spectroscopy.Of these,Compounds 6 and 7 are new compounds.Furthermore,five compounds were identified from the ethyl acetate part,namely(6R,7E)-9-hydroxy-4,7-megastigmadien-3-one(1),blumenol A(2),methyl3-(2,4-dihydroxy-5-methoxyphenyl)propionate(3),p-coumaric acid(4),p-hydroxybenzoic acid(5),and two new compounds were identified from the water part,namely nonikojic A(6)and nonikojic B(7).4.Compounds 1-7 were screened for cellular glucose uptake activities in vitro,and it was found that Compounds 1 and 2 had significant activities in improving insulin resistance.In-depth efficacy and mechanism studies found that both Compounds 1 and 2 significantly promoted the glucose uptake and consumption,and improved the insulin resistance in insulin-resistant Hep G2 cells.Moreover,they also alleviated oxidative stress state and up-regulated the expression of Nrf2/ARE pathway related proteins and genes.Meanwhile,it was further confirmed that Compounds 1and 2 improved the insulin resistance of Hep G2 cells by activating the Nrf2/ARE pathway through molecular docking experiments.In this paper,fermented Noni juice and its active compounds were studied to improve insulin resistance through a variety of in vivo and in vitro experiments.And the role of fermented Noni juice in improving insulin resistance and T2DM by activating the Nrf2/ARE pathway and its active substances were elucidated.This study provides basic materials and theoretical support for the further research and development of fermented Noni juice and new T2DM drugs.