Changes in Antioxidant Activity of Alcalase-Hydrolyzed Soybean Hydrolysate under Simulated Gastrointestinal Digestion and Transepithelial Transport

Peptides from Alcalase-hydrolyzed soybean protein hydrolysate(SPH)may hold the potential as natural antioxidants.In addition,the effect of human gastrointestinal(GI)tract on peptide bioavailability needs to be explored.In this study,the impact of simulated GI digestion and transepithelial transport on various antioxidant properties of SPH were investigated.SPH displayed DPPH radical scavenging(IC50=4.22 mg/m L),ABTS·+radical scavenging(IC50=2.93 mg/m L),reducing power and metal ion-chelating activities(IC50=0.67 mg/m L).Furthermore,SPH significantly(P<0.05)inhibited the generation of intracellular reactive oxygen species(ROS)in Caco-2 cells.After simulated GI digestion,the antioxidant properties of SPH were enhanced,except for a decrease in ABTS·+radical scavenging activity.After transepithelial transport,the permeates maintained partial antioxidant activity and the LC-MS/MS data further identified the absorbed soybean peptides.These results suggest that SPH contains the antioxidant peptides that are potentially bioavailable and can be regarded as a promising source of functional food ingredients.

Herba Epimedii′s biotransformation in vitro simulated gastrointestinal digestion and faecal fermentation systems

OBJECTIVE Epimedium is rich in a variety of beneficial active ingredients,and has been widely used in the ethnopharmacological practices,however,its biotransformation in gastrointestinal digestions remain unclear.This study aimed to investigate the dynamic changes of components and biological activity of Epimedium in the in vitro simulated digestion and subsequent human faecal fermentation.METHODS The models of in vitro simulated saliva,gastric and intestinal digestion,as well as colonic fermentation were constructed to simulate the digestion process of Epimedium.The dynamic changes of components of Epimedium during the simulated digestions in vitro and subsequent human faecal fermentation were investigated by UPLC-MS,HPLC-DAD combined with principal component analysis(PCA)and multi-ingredient quantitative analysis.RESULTS A variety of metabolites with high contents were produced after 0.5 h of intestinal digestion and colonic fermentation 0.5 h.Application of PCA to HPLC data showed the obvious separation of colonic fermentation 0.5 h stage samples from other colonic fermentation stages samples(24,48 and 72 h).Additionally,non-digestion and saliva digestion stage samples clustered together,and there was obvious separation between intestinal digestion samples and gastric digestion samples.The contents of epimedium C,icariin and baohuside I all increased significantly after intestinal digestion[58.70±7.08,47.15±5.68 and(12.78±0.55)mg·g^(-1)]compared with gastric digestion[29.00±5.65,17.40±4.55 and(2.77±0.19)mg·g^(-1)].There were significant differences between sample after 0.5 h of colonic fermentation[64.22±9.32,51.26±6.33 and(16.68±3.19)mg·g^(-1)]and other time points(24,48 and 72 h)in components and the contents of active ingredient,and the content of these components all decreased with the fermentation time.The ability of scavenging ABTS free radicals[IC50=(0.29±0.02)g·L^(-1)]increased significantly compared with gastric digestion[(1.57±0.02)g·L^(-1)],and after 0.5 h of colonic fermentation,the ability also increased significantly.CONCLUSION Gastrointestinal digestion had a significant impact on the contents of active components in Epimedium,and the metabolism of these components mainly occurred in the colon.The intestinal digestion and colonic fermentation significantly improved the anti-ABTS activity of epimedium.

The dual-function of bioactive peptides derived from oyster (Crassostrea gigas) proteins hydrolysates

Oysters(Crassostrea gigas)have a wide range of functionality due to their nutritional and bioactive components. However, the bioactive peptides of oyster proteins are rarely reported, particularly their antidiabetes effects and antioxidants. Oyster proteins were extracted from fresh oysters using phosphatebuffered saline and simulated gastrointestinal digestion was performed. The degree of hydrolysis(DH), structural characterization, molecular weight(Mw)distribution, free amino acid, anti-diabetic activity, and antioxidant activity were studied during in vitro simulated gastrointestinal digestion. The results showed that the α-glucosidase inhibitory activity, α-amylase inhibitory activity, DPPH radical scavenging activity, and ABTS radical scavenging activity of the oyster protein gastrointestinal digest were increased(P < 0.05)from 0 to 33.96%, from 9.17% to 44.22%, from 9.01 μg trolox/mg protein to 18.48 μg trolox/mg protein, and from 21.44 μg trolox/mg protein to 56.21 μg trolox/mg protein, respectively. Additionally, the DH, β-turn structure, fluorescence intensity, free amino acid, and short peptide content(Mw < 1 000 Da)increased in the simulated gastrointestinal digestion. These results indicate that the digestive hydrolysates obtained from oyster proteins could be used as natural anti-diabetic and antioxidant agents.

Purifi cation, characterization and hypoglycemic activity of glycoproteins obtained from pea (Pisum sativum L.)

This study aimed to isolate and characterize the structures of glycoproteins from peas and determine their hypoglycemic activity.The crude pea glycoproteins(PGP)were extracted by hot water and purified by diethylaminoethyl(DEAE)-Sepharose chromatography and Sephadex G-100 size-exclusion chromatography in sequence.Then three main fractions were obtained,namely PGP1,PGP2 and PGP3,with molecular weights of 897615,846740 and 1194692 Da,respectively.The physical and chemical properties of the three fractions were evaluated and compared by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance(NMR),scanning electron microscope(SEM),high performance liquid chromatography(HPLC)and other analytical techniques.The fraction PGP2 with the highest hypoglycemic activity,was screened using the Caco-2 monolayer cell model.It can inhibit the uptake of glucose in the small intestine,as well as the activities of maltase and sucrase.After simulated gastrointestinal digestion,PGP2 signifi cantly enhanced the inhibitory effect of α-glucosidase,and slightly reduced the inhibitory ability ofα-amylase.In summary,PGP2 possessed strong hypoglycemic activity after digestion.These results indicated that PGP2 has the potential to be developed into a functional food or natural medicine for the treatment of type 2 diabetes mellitus.

Microencapsulation of immunoglobulin Y: optimization with response surface morphology and controlled release during simulated gastrointestinal digestion

Immunoglobulin Y(Ig Y)is an effective orally administered antibody used to protect against various intestinal pathogens,but which cannot tolerate the acidic gastric environment.In this study,Ig Y was microencapsulated by alginate(ALG)and coated with chitooligosaccharide(COS).A response surface methodology was used to optimize the formulation,and a simulated gastrointestinal(GI)digestion(SGID)system to evaluate the controlled release of microencapsulated Ig Y.The microcapsule formulation was optimized as an ALG concentration of 1.56%(15.6 g/L),COS level of 0.61%(6.1 g/L),and Ig Y/ALG ratio of 62.44%(mass ratio).The microcapsules prepared following this formulation had an encapsulation efficiency of 65.19%,a loading capacity of 33.75%,and an average particle size of 588.75μm.Under this optimum formulation,the coating of COS provided a less porous and more continuous microstructure by filling the cracks on the surface,and thus the GI release rate of encapsulated Ig Y was significantly reduced.The release of encapsulated Ig Y during simulated gastric and intestinal digestion well fitted the zero-order and first-order kinetics functions,respectively.The microcapsule also allowed the Ig Y to retain 84.37%immune-activity after 4 h simulated GI digestion,significantly higher than that for unprotected Ig Y(5.33%).This approach could provide an efficient way to preserve Ig Y and improve its performance in the GI tract.

Effects of Hericium erinaceus polypeptide on lowering blood lipids of mice with hyperlipidemia induced by a high-fat diet

Hericium erinaceus polypeptide(HEP)was prepared by an ultrasound-microwave assisted enzymatic method.Using an ultrafiltration membrane with molecular weights of 5 and 10 kDa,HEP was fractionated into three fractions,namely,(HEP-I(<5 kDa),HEP-II(5–10 kDa),and HEP-III(>10 kDa)).In vitro chemical methods were used to compare the antioxidant and hypolipidemic abilities of the polypeptide fractions from H.erinaceus before and after simulated gastrointestinal digestion.By constructing a hyperlipidemia model,the hypolipidemic ability of the high active fraction(HEP-II)was verified.The results showed that the antioxidant and hypolipidemic abilities of the polypeptide fractions from H.erinaceus did not change dramatically during simulated gastrointestinal digestion in vitro.The polypeptide fractions from H.erinaceus exhibited high tolerance to simulated gastrointestinal digestion in vitro,with strong antioxidant and hypolipidemic activities.HEP-II with a molecular weight of 5–10 kDa had the best stability,antioxidant,and hypolipidemic abilities in gastrointestinal digestion.The secondary structure of HEP-II was mainly composed of random coil(18.36%)andα-helix(47.71%)structures,which was beneficial to the hypolipidemic ability of HEP-II.Animal experiments showed that compared to the high-fat model group,HEP-II could inhibit the weight gain of the mice,decrease the liver index and serum levels of the serum total cholesterol(TC),triglycerides(TG),low-density lipoprotein cholesterol(LDL-C),nitric oxide synthase(NOS),alanine aminotransferase(AST),and glutamic-pyruvic transaminase(ALT),increase the levels of glutathione peroxidase(GSH-Px)and high-density lipoprotein cholesterol(HDL-C),decrease the arteriosclerosis index(AI),and improve the hemorheological indices of the mice.In addition,the whole blood and plasma viscosities of the mice decreased,and HEP-II increased the level of superoxide dismutase(SOD)in the liver,reducing the level of malondialdehyde(MDA),and the degree of oxidative stress in the liver of hypolipidemia mice.Furthermore,HEP-II improved liver steatosis.These results indicated that the polypeptide fractions from H.erinaceus all had a potential hypolipidemic effect,and HEP-II had the strongest potential hypolipidemic effect.

Development of milk powder containing Lactobacillus plantarum NCIMB 8826 immobilized with prebiotic hi-maize starch and survival under simulated gastric and intestinal conditions

The objectives of this study were to develop a probiotic milk powder containing Lactobacillus plantarum NCIMB 8826 immobilized with prebiotic Hi-maize starch and to analyze cell viability after spray drying and exposure to simulated gastric and intestinal conditions.Milk powders containing free L.plantarum and cells immobilized with Hi-maize starch were assessed.Powders were evaluated during storage at 4°C for 15 days.After spray drying,at 0 and 15 days of storage both treatments had over 8 log CFU/g of viable cells and there were higher viable counts found for immobilized cells compared to free cells after 120 min in simulated gastric fluid.At 15 days of storage,immobilized cells had higher viable counts than free cells after exposure to simulated intestinal fluid for 120 min.The combined probiotic and prebiotic milk powder had stable viable cell counts at refrigerated storage conditions and under simulated gastric and intestinal transit.