Study On The Beneficial Effect And Mechanism Of Mulerry Anthocyanins On Glucose Metabolism Regulation

Anthocyanins are a class of water-soluble polyphenol pigments widely distributed in the plant kingdom and have a positive effect on human health.Studies have shown that anthocyanins have a series of physiological functions.Long-term consumption of anthocyanins can reduce the risk of diabetes and obesity,protect the nervous system,reduce the incidence of inflammation and cardiovascular disease,and suppress the occurrence of cancer.Mulberry is an anthocyanin-rich berry that can be used as a daily edible fruit or raw material for fruit wines,juices,jams,and canned foods.It is reported that mulberry has an adjuvant therapeutic effect on anaemia,coronary heart disease,hypertension,etc.However,there are few reports on its hypoglycemic effect,so it is of great significance to explore the regulation of mulberry anthocyanin on glucose metabolism.In this paper,anthocyanins are extracted from mulberry fruit,kinds and contents of anthocyanins and the antioxidant activity are determined after further isolated and purified.In vitro,HepG2 and L02 cell lines were used to evaluate the hypoglycemic activity of mulberry anthocyanins extract(MAE)as well as to investigate its possible mechanism.Models of diabetic mice and Caenorhabditis elegans were used to evaluate the hypoglycemic effect of MAE in vivo.Results were as follows,1.Separating and purifying the anthocyanin extract from fresh mulberry fruit,and the extract contained cyanidin-3-glucoside(472 ± 9.23 mg/g),cyanidin-3-rutinoside(273 ±5.12 mg/g)and pelargonidin-3-glucoside(14 ± 0.29 mg/g).The IC50 values of DPPH and ABTS were 283 ± 2.75 μg/mL and 275 ± 3.56 μg/mL,respectively.2.MAE could increase glucose consumption,glucose uptake and glycogen content in two hepatocytes.Moreover,MAE inhibited the expression of gluconeogenic related proteins,and promoted the expression of glycogen synthesis-related proteins.3.Establishing an insulin resistance model in HepG2 cells by high glucose and palmitic acid stimulation.Glucose consumption and uptake as well as glycogen content were obviously restored in model cells treated with MAE,along with gluconeogenesis related enzyme activity decreased,resulting in insulin resistance improvement.This may be related to the activation of PI3K/AKT and AMPK signaling pathways by mulberry anthocyanins.4.Using hydrogen peroxide or high glucose/palmitic acid to stimulate HepG2 cells produce oxidative stress.Nrf2 and p38 MAPK were stimulated but JNK phosphorylation was inhibited in cells with MAE treatment,increasing the ability of cells to resist oxidative damage and enhancing insulin signal transduction to maintain the normal glucose metabolism.5.The blood glucose level was significantly decreased and the oral glucose tolerance was increased in db/db mice after gavage of MAE in concentrations of 50 mg/kg BW/day and 125 mg/kg BW/day for 8 weeks.Serum triglyceride,total cholesterol,low density lipoprotein,glycosylated serum protein,insulin,leptin levels were decreased,while adiponectin level was increased in mice administrated with MAE.MAE could also reduce the content of triglycerides and glycogen in the liver,increase the content of glycogen in muscle and maintain the normal morphology of islets.It was uncovered that MAE could reduce the expression of inflammatory cytokines in adipose tissue and up-regulate the expression of AKT and AMPK in liver,muscle and adipose tissue,which played a positive role in diabetes mellitus improvement.6.Lifespan of Caenorhabditis elegans was prolonged when fed with MAE-added diet,compared with nematodes fed with OP50 alone.MAE also prevented paraquat or high glucose-induced life-span shortening of C.elegans,while protective effects of MAE on worms were not observed in daf-16(-)mutant,indicating that MAE extended the lifespan of nematodes by activating DAF-16/FOXO.7.Data about transcriptome of C.elegans under normal diets,fed with high glucose diets and high glucose diets supplied with mulberry anthocyanins were analyzes and integrated.The signaling pathways influenced by MAE involved nematode fat metabolism,cellular processes,growth,senescence,and metabolic processes.