| Type Ⅱ diabetes brought great economic and living burden to people.Currently,drug therapy is the main treatment for type Ⅱ diabetes,however,this method may case drug resistance and side effects.Momordica charantia is a common fruit and vegetable.As both food and medicine,M.charantia has been widely distributed in tropical and subtropical regions.Momordica charantia and its polysaccharides have anti-diabetic effects,nonetheless the mechanism is still unclear.Previous studies have shown that as an emerging food processing method,probiotic fermentation can increase nutrients,enhance bioactivities,and improve the flavor of products,however,few studies have been reported on the alterations of components in M.charantia after probiotic fermentation.Consequently,the present study was to investigate the effect of fermentation by Lactobacillus plantarum NCU116(a strain with good fermentation performance screened by our team)on the physico-chemical properties and anti-diabetic functionalities of M.charantia and its polysaccharides,based on the instrumental analysis and molecular biology methods.The main contents and conclusions are as follows:(1)The effect of fermentation with L.plantarum NCU116 on the physicochemical properties of M.charantia juices was investigated.The organic acids,volatile compounds,total saponins contents,and phenolic profiles of fermented and non-fermented M.charantia juices(FJ and NFJ)were determined by gas chromatography,high performance liquid chromatography,gas chromatography-mass spectrometer,UV spectrum,and ultra performance liquid chromatography quadrupole time-of-flight mass spectromery analysis.The results showed that the contents of organic acids(acetic,butyric,valeric,lactic,and malic acids)in M.charantia juices significantly increased after fermentation with L.plantarum NCU116,compared with NFJ(P < 0.05).The volatile profile of M.charantia juices was altered after fermentation by reducing aldehydes and terpenoids,while increasing alcohols and acids.The total saponins content of FJ was remarkably lower than that of NFJ,while the total phenolics content were notably higher than that of NFJ(P < 0.05).Moreover,the phenolic profile of M.charantia juice was alternated after fermentation by increasing 4-hydroxylbenzoic acid,vinylphenol,phloretic acid,p-coumaric acid,catechol,vinylcatechol,vanilin,trans-cinnamic acid,ellagic acid,dihydrocaffeic acid,vanillic acid,protocatechuic acid,pyrogallol,gallic acid,and decreasing caffeic acid.(2)The effect of fermentation with L.plantarum NCU116 on the physicochemical characteriazation of M.charantia polysaccharides were evaluated.The monosaccharide composition,molecular mass distribution,and functional group of fermented and non-fermented M.charantia polysaccharides(FP and NFP)were analyzed by ion chromatography,high performance size exclusion chromatography,and fourier transform infrared spectroscopy analysis.The results showed that FP was mainly composed of three monosaccharides,including galacturonic acid,galactose,and glucose.The proportion of glucose in FP decreased,compared with NFP.The peak profile of M.charantia polysaccharides with small molecular weight was changed after fermentation,whereas polysaccharides with large molecular weight was unchanged.The functional group of M.charantia polysaccharides was unchanged after L.plantarum fermentation.(3)The effect of fermentation with L.plantarum NCU116 on the anti-diabetic properties of M.charantia and its polysaccharides were evaluated using an animal model of type Ⅱ diabetes established by high-fat diet and low-dose streptozotocin.The experimental rats were divided into 10 groups: control group,diabetes group,diabetic rats treated with FJ group,diabetic rats treated with NFJ group,diabetic rats treated with low-dose(50 mg/kg)of FP group,diabetic rats treated with middle-dose(100 mg/kg)of FP group,diabetic rats treated with high-dose(200 mg/kg)of FP group,diabetic rats treated with middle-dose(100 mg/kg)of NFP group,control rats treated with middle-dose(100 mg/kg)of FP group,control rats treated with middle-dose(100 mg/kg)of NFP group.Rats were oral administrated with FJ,NFJ,FP and NFP for 4 weeks.The resutls showed that FJ could improve the body weight,water intake,fasting blood glucose(FBG),serum insulin,serum lipids,and oxidative stress levels,decreased serum glutamic-pyruvic transaminase(ALT),glutamic oxaloacetic transaminase(AST),creatinine(CREA-J),urea nitrogen(UREA),uric acid(UA),and kidney index,as well as restored the morphology of pancreas,liver,and kidney in type Ⅱ diabetic rats.FJ had more favorable effects on regulating the serum insulin,UA,and urea levels in type Ⅱ diabetic rats than NFJ(P < 0.05).Moreover,FP could improve the body weight,food and water intakes,reduced FBG,glycated serum protein(GSP),and serum insulin levels,modulated serum lipids and oxidative stress,decreased ALT,kidney index,CREA-J,and UREA levels,as well as restored the morphology of pancreas,liver,and kidney in type Ⅱ diabetic rats.Compared with NFP,FP improved the body weight,food intakes,and insulin resistance more favorably in type Ⅱ diabetic rats(P < 0.05).(4)Based on UPLC-Q-TOF/MS,the effect of fermented and non-fermented M.charantia and its polysaccharides on the metabolites of serum and urine in type Ⅱ diabetic rats was investigated.The results showed both FJ and NFJ significantly improve amino acids and lipids metbaolisms in type Ⅱ diabetic rats.FJ improved the ethyl esters,glucosylceramide E,methyl ethanolamines,diacylglycerols,monoacylglycerols,lysomonomethyl-PE,lysophosphatidylethanolamine,and ergosterols metabolism in type Ⅱ diabetic rats more effectively than NFJ.Additionally,both FP and NFP modulated carbohydrates,amino acids,and lipids metabolisms in type Ⅱ diabetic rats.FP had more favorable effects on the aminoacyl-tRNA biosynthesis,arginine and proline metabolism,D-arginine and D-ornithine metabolism,nicotinate and nicotinamide metabolism,pentose and glucuronate interconversions,starch and sucrose metabolism,steroid hormone biosynthesis in type Ⅱ diabetic rats,compared with NFP.Additionally,FP and NFP improved carbohydrates,amino acids,and lipids metabolism in normal rats.(5)The effect of fermented and non-fermented M.charantia and its polysaccharides on the gut microbiota of type Ⅱ diabetic rats were evaluated.FJ could increase the abundance of Bacteroides caecigallinarum,Oscillibacter ruminantium,Bacteroides thetaiotaomicron,Prevotella loescheii,Prevotella oralis and Prevotella melaninogenica,and the concentrations of acetate,propionate,butyrate,and total SCFAs in the colonic contents of type Ⅱ diabetic rats,compared with NFJ.Furthermore,FP could increase the abundance of Lactococcus laudensis and Prevotella loescheii,and the concentrations of acetate and total SCFAs in the colonic contents of diabetic rats,compared with NFP.In conclusion,this study fully compared the physicochemical properties between of fermented and non-fermented M.charantia and its polysaccharides.Besides,the anti-diabetic effects of fermented and non-fermented M.charantia and its polysaccharides were investigated using an animal model of type Ⅱ diabetes.The results showed L.plantarum NCU116 fermentation could to some extent modified the physico-chemical properties of M.charantia and its polysaccharides,to improve their anti-diabetic properties and enhance their regulatory effects on the gut microbiota and metabolism in type Ⅱ diabetic rats. |
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