Constituent Analysis Of The Ethanol Extract Of Chimonanthus Nitens Oliv.leaves And Its Effect On Anti-hyperglycemic

The paper investigated the chemical constituent and antihyperglycemic activity of the Chimonanthus nitens Oliv.leaves ethanol extract,and provided a scientific evidence for developing drugs or the nutraceutical health supplement produced from Chimonanthus nitens Oliv.leaves in the management of diabetes.The crude ethanol extract?CEE?of Chimonanthus nitens Oliv.leaves was purified by polyamide column chromatography with gradient ethanol elutions to collect four kinds of ethanol eluates including water eluate?WE?,30%ethanol eluate?30%EE?,50%EE and 70%EE.Then these ethanol eluates were used for?-glucosidase inhibition assay to acquire the fraction with the best inhibitory effect,and the constituents of the fraction were analyzed and potential active compounds were further screened.What's more,the effect and mechanism of the active fraction on antihyperglycemic was eveluated by establishing the diabetic model mice induced by the combination of high-glucose-fat diet-fed and intraperitoneal injection of streptozotocin.Results were as follows:?1?Among these four kinds of ethanol eluates,the fraction of 50%EE exhibited the best inhibition with IC₅₀0 of 0.376 mg/mL.Eight compounds including rutin?1?,hyperin?2?,isoquercitrin?3?,luteoloside?4?,astragalin?6?,quercetin?13?,naringenin?14?,kaempferol?15?were identified by compared with standard substances as well as proper luteolin-5-O-glucoside?5?,kaempferol-7-O-rhamnoside?9?,5-hydroxy-3',4'-dimethoxyl-flavone-7-O-glucoside?10?,kaempferol-3-O-acetyl-galac-toside?11?were identified from50%EE by liquid chromatography-mass spectrometry?LC-MS?analysis.The experiments of ultra-filtration combined with liquid chromatography-mass spectrometry?UF-LC-MS?guided quercetin and kaempferol as the main factors for 50%EE showing high inhibitory activity on?-glucosidase,and they inhibited?-glucosidase in a mixed-type manner with IC₅₀0 of 66.8 and 109?g/mL,respectively.?2?After 4 weeks treatment of 50%EE,fast blood glucose?FBG?level,glucose tolerance,insulin sensitivity index?ISI?,serum triglyceride?TC?,total cholesterol?TG?,low-density lipoprotein cholesterol?LDLC?and high-density lipoprotein cholesterol?HDLC?were significantly improved.Activity of superoxide dismutase?SOD?,glutathione peroxidase?GSH-Px?,and catalase?CAT?as well as total antioxidant capacity?T-AOC?in serum and liver were apparently enhanced,and malondialdehyde?MDA?in serum and liver were significantly reduced.The results of correlation analysis between glycolipid metabolism and antioxidant capacity in 50%EE-treated diabetic model mice indicated that glucose metabolism was positively correlated to antioxidant capicity,lipid metabolism showed varying degrees of correlation relationship with different antioxidant indexes,but not all significant.In addition,50%EE increased serum insulin level,regulated liver function indicators and improved the tissue morphology of pancreas islets and liver,which suggested that 50%EE showed protection for architecture and function of pancreas islet and liver.?3?Glucose metabolism genes expression analysis of skeletal muscle guided COE exerted glucose-lowering effect through following two ways:on the one hand,COE enhanced insulin sensitivity by up-regulating the transcription level of GLUT4,in addition,it enhanced the insulin signaling pathway to promote the translocation of GLUT4 and up-regulated thermogenesis genes expression including PGC-1?and UCP-1;on the other,GLUT1 expression was also increased in both transcription and translation level in the presence of COE.These two ways resulted in promoting glucose uptake of skeletal muscle,thus leading to the reduction of blood glucose level.