Novel soybean peptide iglycin ameliorates insulin resistance of high-fat diet fed C57BL/6J mice and differentiated 3T3L1 adipocytes with improvement of insulin signaling and mitochondrial function

Soy consumption has been associated with potential health benefits in reducing chronic diseases.These physiological functions have been attributed to soy proteins or more commonly to bioactive peptides.Thus,more studies are required to identify these bioactive peptides,and elucidate their biological mechanisms of action.In the present study,a novel peptide iglycin was purifi ed from soybean seeds with a molecular mass of 3.88 k Da.Thereafter,iglycin reduced fasting blood glucose and restored insulin sensitivity of C57 BL/6 J mice on a high-fat diet with increased phosphorylation of insulin receptor substrate 1(IRS1)and AKT in adipose tissue.Furthermore,it improved glucose uptake,induced translocation of intracellular GLUT4 to plasma membrane and activation of insulin signaling in adipocytes under insulin-resistant condition.In addition,it decreased reactive oxygen species production,lipid peroxidation and inhibited adipocyte apoptosis with improved mitochondrial function as evidenced by up-regulation of succinate dehydrogenase activity,mitochondrial membrane potential and intracellular ATP store.These data suggested that iglycin ameliorated insulin resistance via activation of insulin signaling,which was associated with inhibition of oxidative stress,adipocyte apoptosis,and improvement of mitochondrial function.

Effect of Soybean Peptides on in vitro Ruminal Fermentation and Microbial Population

This study was conducted to investigate the effect of Soybean Peptides(SPs) on ruminal fermentation and microbial diversity in vitro. Four levels of SPs supplements(0, 0.25%, 0.50% and 0.75% dry matter basis) were tested. p H, NH3-N, Neutral Detergent Fiber(NDF), Acid Detergent Fiber(ADF), Dry Matter Digestibility(DMD) and the Total Volatile Fatty Acid(TVFA) were measured at 6, 24, 48 h of in vitro mixed incubation the fluids. Microbial populations were determined at 24 h and Microbial Proteins(MCP) were determined at 24 and 48 h. The gas production after 48 h in vitro incubation presented linear growth(p<0.05) and the highest content was the level of 0.5% SPs(dry matter basis). NH3-N concentration reached the highest concentration with 0.75%(dry matter basis) at 48 h. p H linearly increased(linear, p<0.05) from 6 to 48 h. The digestion of DMD increased with increasing doses of SPs at 24 h. NDF and ADF linearly(p<0.01) decreased by adding SPs. The concentration of TVFA linearly increased(p<0.05) at 6, 24 and 48 h, and reached the highest concentration at the level of 0.75%(dry matter basis). SPs decreased(p<0.05) the molar proportion of acetate and propionate, respectively at 24 and 48 h. Acetat to Propionate ratio(A/P; linear, p<0.05) increased at 48 h, and reached the greatest value at the level of 0.75%(dry matter basis) at 48 h. The populations of rumen Ruminococcus flavefaciens(R. flavefaciens), Ruminococcusalbus(R. albus), Fibrobacter succinogenes(F. succinogenes), Butyrivibrio fibrisolvens(B. fibrisolvens), Streptococcus bovis(S.bovis), Ruminobacter amylophilus(R. amylophilus) and Succinimonas amylolytica(S. amylolytica) were analyzed based on the total rumen bacterial 16 S ribosomal deoxyribonucleic acid(r DNA). The relative abundance of R. flavefaciens and R. albus increased at 24 h, but the relative abundance of F. succinogenes decreased at this time. The incubation of SPs had no effect on the abundance of S. bovis and R. amylophilus. The relative abundance of B. fibrisolvens and S. amylolytica reached the greatest value(p<0.05) at middle doses of SPs inclusion at 24 h. The value of MCPs linearly increased(p<0.05) at 24 and 48 h. These results showed that SPs could improve in vitro fermentation and nutrient digestion of feed substrates, and had the ability to modulate the ruminal fermentation pattern by regulating the composition of functional rumen microbes. Hence, SPs might be a potential feed additive applied in the diets of ruminants.

A Study on Anti-oxidative Activity of Soybean Peptideswith Linoleic Acid Peroxidation Systems

Soybean bioactive peptides（SBPs） were prepared from the isolated soybean protein by proteolysis with an alkaline protease, alcalase, at 50℃ and pH = 8.0. The dependence of hydrolysis time on hydrolysis degree and molecular weight distribution were examined. The hydrolysate was fractionated on a Sephadex G-25 column and the anti-oxidative activities of the fractions were detected by the method of pyrogallol auto-oxidation. The average chain length of soybean peptides that have anti-oxidative activity was estimated to be about 7. The anti-oxidative properties of the soy- bean peptide were also studied by using linoleic acid peroxidation systems. The optimal condition of the peroxidation system was set up, Vc/Cu^2 ＋ as the inducer at pH = 7.4 and 25 ℃. In addition, soybean peptides show higher antioxidative activity compared with GSH.

Preparation and Antioxidative Effects of Soybean Peptides

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Transcriptome analysis revealing the mechanism of soybean protein isolates and soybean peptides on Lacticaseibacillus rhamnosus Lra05

To further investigate the promoting effect of soybean protein and peptides on Lacticaseibacillus rhamnosus Lra05(L.rhamnosus Lra05),the overall changes of gene expression of it was investigated through transcriptome analysis treated with dPEP and dSPI The results showed that there were 890,113,and 1073 differentially expressed genes(DEGs)in dPEP/MRS,dSPI/MRS and dPEP/dSPI comparison,respectively.Besides,we found dPEP could promote the expression of acc and fab family genes related to fatty acid biosynthesis,but dSPI played the opposite role.Moreover,dPEP stimulated genes clustered in pur family and ribosome protein,responsible for purine and protein synthesis.Interestingly,dPEP suppressed genes regulating peptides and amino acids transportation and dSPI specially inhibited the pyr family genes involved in pyrimidine metabolism.These data revealed the knowledge about the metabolic pathways affected by dPEP and dSPI and provide a preliminary understanding of the relationship between soybean proteins and peptides and L.rhamnosus Lra05.

Effect of Duodenal Soybean Small Peptides Infusion on Mammary Uptake of Amino Acid and Expression of APN in Lactating Goat

The aim of this study was to investigate the effect of duodenal infusion of soybean small peptides(SSP) on mammary uptake of amino acids(AA).Eight Chinese Saanen goats with duodenal fistulae and catheters were used in a crossover design trial.Goats were infused with 0,60,120,180 g/d SSP.The experimental period lasted for 14 d.The results showed:1) milk protein yield and content were increased,with the increment in milk protein yield being significant(P【0.05).Milk fat yield and content were decreased with the increased amount of SSP infused(P【0.05).2) Mammary plasma flow was not changed(P】0.05) by SSP infusion though the average was slightly higher.Mammary plasma flow/milk yield was decreased by SSP infusion and there was significant difference between the 120 g/d treatment and the control(P【0.05).3) Compared with the control treatment,uptakes of most free amino acids were increased in the 60 and 120 g/d treatments,but decreased by the 180 g/d treatment.The uptakes of all peptide-bound essential amino acids(PB-EAA) were increased except for PB-Ile.Uptake of PB-Val,PB-Leu, PB-Phe,PB-Thr,PB-Met and PB-Lys was highest in the 120 g/d treatment.Among the peptide-bound nonessential amino acids(PB-NEAA),uptake of PB-Ser,PB-Tyr,and PB-Pro was increased(P【0.05) while that of PB-Gly was decreased(P】0.05).4) With the exception of Lys,secretion of all essential AA(EAA) was increased by SSP infusion from 0-120 g/d(P【0.05),while in the 180 g/d treatment the increase was not significant and was lower than that in the 120 g/d treatment.5) The expression of APN was increased by SSP;in the 60,120,180 g/d treatments expression was 13.55-,18.69-,and 10.01-fold over that of the controls.Conclusion:SSP might be used as substrates for milk protein synthesis by mammary gland,and can increase synthesis and secretion of milk protein.There was reason to believe that uptake and use of AA was either saturated or inhibited at high levels of infusion of SSP.Increased APN expression with infusion of SSP related to mammary uptake of PBAA by mammary gland,which suggested that APN was one of the peptidases regulating use of AA from small peptides in mammary tissue.

Antioxidant and free radical-scavenging activities of black soybean peptides (BSP)

The antioxidant and free radical-scavenging activities of black soybean peptides(BSP)fractions(Fra-Ⅰ,Fra-Ⅱ,Fra-Ⅲ)were investigated using reducing power and DPPH·/superoxide/hydroxyl radical-scavenging assay.The reducing power activity of Fra-Ⅲwas closer to that of BHT but lower than that of ascorbic acid.Fra-Ⅲshowed the strongest scavenging activity against free radicals.The radical-scavenging effect was in a dose-dependent manner and the IC50 values for DPPH·,superoxide and hydroxyl radicals were found to be 1.873,1.684 and 1.735 mg/mL,respectively.Amino acid analysis showed that Fra-Ⅲhad high hydrophobic amino acids(HAA)content and hydrophobicity.The molecular weight distribution of Fra-Ⅲwas found to vary from 100 to 1,000 Da mainly.The antioxidant activity of Fra-Ⅲis clearly related to the amino acid composition,the content of HAA and the molecular mass.The present study suggests that BSP with low molecular weight are useful nutritional antioxidant and potential functional factor for anti-aging.

Effects of Soybean Active Peptides on Performance and Serum Lipid of 14-day Old Early Weaned Piglets

This purpose was to evaluate the efficacy of soybean active peptides (SAP) in 14-day old early weaned piglets feed. Eighteen crossbreed piglets Duroc ×Landrace ×Yorkshire (14-day old) were randomly divided into three groups with six piglets each group. Control was fed with 8% animal plasma (AP). Trial 1 was fed with 4.9% AP and 4.9% SAP. Trial 2 was fed with 12.62% SAP. This raising period was 30 days and divided into three periods with earlier period (0-15 days), latter period (16-30 days) and whole period (0-30 days). The results showed that average daily gains (ADG) in trial 1 were increased 16.33%, 12.64% and 13.94% (P >0.05) and Efficiency of feed conversions (EFC) improved 17.35%, 11.40% and 13.46% than control in respective periods; ADG in trial 2 were reduced 12.24%, increased 4.21% and reduced 0.40% (P>0.05) and EFC were improved 19.81%, 13.08% and 15.76% than control in respective periods. Means of TG and LDL-C/ HDL-C in trial 1 were lowest in three groups and reduced 6.54% (P >0.05) and 0.96% than control. Means of TG, TC, LDL-C, HDL-C, LDL-C/ HDL-C were the highest in trial 2 among three groups and increased 8.93% (P >0.05), 39.69% (P <0.05), 34.94% (P >0.05), 27.31% (P >0.05) and 5.96% than control respectively. It was concluded that substituting part Ap for SAP in 14-day old piglets Feed was practicable.