Beijing Key Laboratory of Nutrition

Beijing, China

Beijing Key Laboratory of Nutrition

Beijing, China
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Zhang H.,China Agricultural University | Liu X.,Beijing Key Laboratory of Nutrition | Ding Q.,COFCO | Jiang L.,China Agricultural University | And 2 more authors.
Molecular Nutrition and Food Research | Year: 2012

Scope: In this study, we intend to clarify the role that milk proteins and fat may play in affecting the bioavailability and the antioxidant activity of jujube juice phenolics. Methods and results: Three milk preparations-skimmed milk, milk fat, and whole milk were produced to represent milk protein, milk fat, and milk protein and fat together, respectively. The bioavailability of phenolics and the rat plasma antioxidant capacity were measured for 8 h after the consumption of jujube juice with and without milk preparations. The addition of skimmed milk to jujube juice resulted in significant changes in the plasma kinetics profile of phenolics, rather than affecting the overall absorption. Milk fat did not interact with jujube juice phenolics. However, when jujube juice was ingested with whole milk, a significant reduction of the bioavailability of phenolics and the maximum increase in plasma antioxidant capacity was observed. Moreover, a consistent increase in the median diameters of the emulsions indicated the formation of complexes of proteins, fat, and phenolics during digestion. Conclusion: The present study suggests that when ingested with jujube juice, milk proteins and fat play different roles in affecting the bioavailability and the antioxidant activity of jujube juice phenolics. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Tian M.,China Agricultural University | Fang B.,Academy of State Administration of Grain | Jiang L.,China Agricultural University | Guo H.,Beijing Key Laboratory of Nutrition | Ren F.,China Agricultural University
Dairy Science and Technology | Year: 2015

Antioxidative peptides derived from food proteins have been screened and characterized in in vitro assays, and several quantitative structure–activity relationship (QSAR) models have been established to understand the structure–activity relationship of the selected antioxidant peptides. However, a systematic evaluation of each fragment that could be produced by a certain protein is still lacking. In this study, all the tripeptides that could possibly derive from bovine beta-lactoglobulin based on its amino acid sequence have been synthesized, and their antioxidant activities were measured using a ferric-reducing antioxidant power assay. Three of the peptides (i.e., LTC, CQC, and GTW) exhibited higher activities than that of glutathione. A QSAR model was also computed using multiple linear regression with divided physicochemical property scores descriptors, and the validity of the model was confirmed by cross-validation and Y-scrambling. The result of the QSAR modeling indicated that the electronic and hydrogen-bonding properties of the amino acids in the tripeptide sequences, as well as the steric properties of the amino acid residues at the C- and N-termini, played an important role in the antioxidant activities of the tripeptides. The antioxidant activities of the tripeptides were generally higher with Cys and Trp amino acid residues in the sequence. The structural characteristics we found may contribute to the further research of antioxidative mechanism. © 2015, INRA and Springer-Verlag France.


Jin J.,China Agricultural University | Zhang B.,CAS Beijing Institute of Genomics | Guo H.,China Agricultural University | Cui J.,China Agricultural University | And 7 more authors.
PLoS ONE | Year: 2012

To analyze the mechanism of the acid tolerance response (ATR) in Bifidobacterium longum subsp. longum BBMN68, we optimized the acid-adaptation condition to stimulate ATR effectively and analyzed the change of gene expression profile after acid-adaptation using high-throughput RNA-Seq. After acid-adaptation at pH 4.5 for 2 hours, the survival rate of BBMN68 at lethal pH 3.5 for 120 min was increased by 70 fold and the expression of 293 genes were upregulated by more than 2 fold, and 245 genes were downregulated by more than 2 fold. Gene expression profiling of ATR in BBMN68 suggested that, when the bacteria faced acid stress, the cells strengthened the integrity of cell wall and changed the permeability of membrane to keep the H+ from entering. Once the H+ entered the cytoplasm, the cells showed four main responses: First, the F0F1-ATPase system was initiated to discharge H+. Second, the ability to produce NH3 by cysteine-cystathionine-cycle was strengthened to neutralize excess H+. Third, the cells started NER-UVR and NER-VSR systems to minimize the damage to DNA and upregulated HtpX, IbpA, and γ-glutamylcysteine production to protect proteins against damage. Fourth, the cells initiated global response signals ((p)ppGpp, polyP, and Sec-SRP) to bring the whole cell into a state of response to the stress. The cells also secreted the quorum sensing signal (AI-2) to communicate between intraspecies cells by the cellular signal system, such as two-component systems, to improve the overall survival rate. Besides, the cells varied the pathways of producing energy by shifting to BCAA metabolism and enhanced the ability to utilize sugar to supply sufficient energy for the operation of the mechanism mentioned above. Based on these reults, it was inferred that, during industrial applications, the acid resistance of bifidobacteria could be improved by adding BCAA, γ-glutamylcysteine, cysteine, and cystathionine into the acid-stress environment. © 2012 Jin et al.


Liu H.N.,Gansu Agricultural University | Zhang C.,Gansu Agricultural University | Zhang H.,China Agricultural University | Guo H.Y.,China Agricultural University | And 4 more authors.
Journal of Dairy Science | Year: 2013

Qula is made from yak milk after defatting, acidifying, and drying. Yak milk caseins are purified from Qula by dissolving in alkali solution. The effects of different pH treatments on the functional and structural properties of yak milk caseins were investigated. Over a broad range of pH (from 6.0 to 12.0), functional properties of yak milk caseins, including solubility, emulsifying activities, and thermal characteristics, and the structural properties, including 1-anilino-8-naphthalene-sulfonate fluorescence, turbidity and particle diameter, were evaluated. The results showed that the yak milk casein yield increased as the pH increased from 6.0 to 12.0. The solubility dramatically increased as the pH increased from 6.0 to 8.0, and decreased as the pH increased from 9.0 to 12.0. The changes in emulsifying activity were not significant. Caseins were remarkably heat stable at pH 9.0. The turbidity of the casein solution decreased rapidly as the pH increased from 6.0 to 12.0, and the results suggested that reassembled casein micelles were more compact at low pH than high pH. At pH values higher than 8.0, the yield of yak milk caseins reached more than 80%. The highest solubility was at pH 8.0, the best emulsification was at pH 10.0 and the greatest thermal stability was at pH 9.0. According to the functional characteristics of yak milk caseins, alkali conditions (pH 8.0-10.0) should be selected for optimum production. These results suggested that pH-dependent treatment could be used to modify the properties of yak milk caseins by appropriate selection of the pH level. © 2013 American Dairy Science Association.


Zhao Y.,China Agricultural University | Zhao Y.,Beijing Key Laboratory of Nutrition | Zhao L.,China Agricultural University | Zheng X.,China Agricultural University | And 5 more authors.
Journal of Microbiology | Year: 2013

In this study, we utilized the nematode Caenorhabditis elegans to assess potential life-expanding effect of Lactobacillus salivarius strain FDB89 (FDB89) isolated from feces of centenarians in Bama County (Guangxi, China). This study showed that feeding FDB89 extended the mean life span in C. elegans by up to 11. 9% compared to that of control nematodes. The reduced reproductive capacities, pharyngeal pumping rate, growth, and increased superoxide dismutase (SOD) activity and XTT reduction capacity were also observed in FDB89 feeding worms. To probe the anti-aging mechanism further, we incorporated a food gradient feeding assay and assayed the life span of eat-2 mutant. The results demonstrated that the maximal life span of C. elegans fed on FDB89 was achieved at the concentration of 1. 0 mg bacterial cells/plate, which was 10-fold greater than that of C. elegans fed on E. coli OP50 (0. 1 mg bacterial cells/plate). However, feeding FDB89 could not further extend the life span of eat-2 mutant. These results indicated that FDB89 modulated the longevity of C. elegans in a dietary restriction-dependent manner and expanded the understanding of anti-aging effect of probiotics. © 2013 The Microbiological Society of Korea and Springer-Verlag Berlin Heidelberg.


Luo J.,China Agricultural University | Guo H.Y.,Beijing Key Laboratory of Nutrition | Ren F.Z.,China Agricultural University
Journal of Dairy Science | Year: 2013

A soft, pasty, high-moisture surface defect occurs with progressive brining of Mozzarella cheese. Addition of calcium is traditionally used to prevent this defect but the underlying mechanism is not clear. Mozzarella cheese was formed into a cylinder inside brine on its plane surface to ensure semi-infinite, unidirectional mass transfer and placed into brine containing 0, 0.1, or 0.25% (wt/wt) calcium chloride. To monitor the effect on cheese composition of calcium in brine, we measured calcium and water contents of the cheese during brining. The extent of calcium loss from the cheese decreased significantly with the addition of calcium. Addition of calcium to a final concentration of 0.25% decreased the loss of calcium from 94.13 to 18.22% from the outside region of the cheese after 30. d, and the water content of the cheese was decreased from 67.8 to 48.8%. To further elucidate the effect of calcium in brine, the Boltzmann method was used to determine the effective diffusion coefficient value, and low-field nuclear magnetic resonance was used to measure the cheese transversal relaxation time. The migration of calcium interfered with salt diffusion. At the end of brining, the amount of water bound to the protein of the cheese significantly increased. Addition of calcium to a final concentration of 0.25% diminished the proportion of bound water by 20.96%. In conclusion, addition of calcium hinders the diffusion of sodium and modifies the distribution of water in Mozzarella cheese during brining. © 2013 American Dairy Science Association.


Fang B.,China Agricultural University | Fang B.,Beijing Key Laboratory of Nutrition | Guo H.Y.,China Agricultural University | Guo H.Y.,Beijing Key Laboratory of Nutrition | And 4 more authors.
FEBS Journal | Year: 2013

Cell-penetrating peptides (CPPs) are a new class of vectors with high pharmaceutical potential to deliver bioactive cargos into cells. Here, we characterized bLFcin6, a six amino acid peptide derived from bovine lactoferricin, as a CPP. Uptake of bLFcin6 was measured by flow cytometry. The ability to delivery siRNA was analyzed in HeLa cells. bLFcin 6 exhibited concentration-dependent uptake and intracellular distribution. Below 7.5 μm, uptake of bLFcin6 was significantly lower than uptake of TAT (P < 0.05) because bLFcin6 has fewer cationic amino acids. Compared to CPP5 (RLRWR) and CPP6 (PFVYLI), bLFcin6 had a significantly higher internalization ratio above 2.5 μm because it has two tryptophan residues. Uptake of bLFcin 6 starts with an ionic cell-surface interaction. It is then rapidly internalized by lipid raft-dependent macropinocytosis, followed by release from macropinosomes into the cytosol and nucleus. Moreover, bLFcin6 formed stable electrostatic complexes with siRNA and delivered siRNA into cells, resulting in significant knockout activity at both the mRNA and protein levels. The knockout activity of siRNA delivered by bLFcin6 was similar to that mediated by TAT, although knockout by bLFcin6 required a higher molar ratio. In this study, bLFcin6 was tested for its ability to act as an siRNA-delivering CPP. © 2012 The Authors Journal compilation © 2012 FEBS.


Cui N.,Gansu Agricultural University | Wen P.C.,Gansu Agricultural University | Liang Q.,Gansu Agricultural University | Liu H.N.,Northwest University for Nationalities | And 6 more authors.
Journal of Animal Physiology and Animal Nutrition | Year: 2015

The objective of this study was to assess the changes in the chemical composition of yak colostrum and transient milk. Samples were collected from 12 yaks on days 1, 2, 3, 4, 5, 6 and 7 post-partum (PP). The gross composition, nitrogen fraction distribution, amino acid (AA) profile and fatty acid (FA) profile were analysed. All the components decreased rapidly during the first 3 days except lactose which increased. The ratio of whey protein to casein protein decreased from 46:54 to 17:83 during the first 7 days PP. The content of all the AAs decreased, while the percentages of eight essential AAs in protein of samples increased during the study period. Monounsaturated FAs and polyunsaturated FAs decreased in the first 7 days PP, whereas saturated FAs increased. In conclusion, the changes in chemical composition were remarkable during the first 3 days. The slight variations, happened during the transient period, are not negligible, which also should be taken into account in the development of yak colostrum supplements. © 2015 Blackwell Verlag GmbH.


Wang X.Y.,Key Laboratory of Functional Dairy | Guo H.Y.,Key Laboratory of Functional Dairy | Zhang W.,China Agricultural University | Wen P.C.,Gansu Agricultural University | And 3 more authors.
Journal of Dairy Science | Year: 2013

We studied the effect of iron saturation level on the osteogenic activity of lactoferrin (LF) in vitro and in vivo. Different iron saturation levels of LF (1.0, 9.0, 38, 58, and 96%) were prepared as the following samples: apo-LF, LF-9, LF-38, LF-58, and holo-LF. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, we observed that the stimulating osteoblast proliferation activity of LF in vitro decreased with increasing iron saturation level at 100 and 1,000. μg/mL. In vivo, 4-wk-old ICR Swiss male mice were randomly divided into 4 groups: blank control (physiological saline), negative control (BSA), apo-LF, and holo-LF. Four groups of mice were injected subcutaneously with physiological saline, BSA, apo-LF, or holo-LF over the calvarial surface twice a day for 5 consecutive days at a dose of 4. mg/kg per day. Bone histomorphometry showed that new bone formation (assessed using tetracycline-HCl labels) tended to be stronger with apo-LF than with holo-LF. Using fluorescence spectroscopy and circular dichroism measurements, we found that exposure of tryptophan increased, α-helix content increased, but β-structure content decreased with increasing iron saturation level. These findings indicated that the osteogenic activity of LF decreases with increasing iron saturation level in vitro and in vivo, which may be related to conformational changes in LF. © 2013 American Dairy Science Association.


Fang B.,China Agricultural University | Fang B.,Beijing Key Laboratory of Nutrition | Zhang M.,China Agricultural University | Zhang M.,Beijing Higher Institution Engineering | And 7 more authors.
Protein Journal | Year: 2012

The biological function of α-lactalbumin (α-LA) depends on its conformation. α-LA can adopt a stable intermediate state induced by heating or pH change. This intermediate state associates with oleic acid (OA) to form an anti-tumor complex. The effect of temperature on the formation the complex has been studied, whereas the effect of pH on complex formation remains unresolved. The effect of pH on tryptophan residues, hydrophobic clusters and secondary structure of Ca2+-depleted bovine α-LA (BLA) was studied by fluorescence spectroscopy and circular dichroism. BLA was found to adopt a more flexible conformation between pH 7.0 and 9.0 with buried hydrophobic clusters. The binding ability of α-LA towards OA and the anti-tumor activity of the corresponding complex were also studied. BLA was found to bind more OA over the pH range of 7.0-9.0 and the corresponding complexes showed a higher anti-tumor activity than those complexes formed under acidic conditions. Our study indicates that alkaline pH aided the formation of the complex as well as its anti-tumor activity. We also propose a possible characteristic structure that facilitates binding of OA. © 2012 Springer Science+Business Media, LLC.

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