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Chitosan (CTS)/chitosan oligosaccharide (COS) and whey protein isolate (WPI) have been frequently used as food supplements, but notably, the interaction between the carbohydrate and the protein may affect the digestibility of protein. Thus, the present study focused on effects of the interaction between CTS/COS and WPI on the protein digestibility. A series of chemical and spectroscopic techniques including gel electrophoresis, gel permeation chromatography, Fourier transform-infrared (FT-IR) spectroscopy, intrinsic fluorescence (IF) spectroscopy, and circular dichroism (CD) spectroscopy were applied. According to the findings, both CTS and COS dramatically reduced intestinal digestibility of WPI, resulting in a decrease of DH by 43.33 % and 52.31 %, respectively. The substitution degree of WPI on CTS was 0.87 g WPI/g CTS, and the electrostatic interaction between amine groups of CTS and carboxyl groups of WPI caused changes in WPI's stability, microstructure, and fluorescence intensity. Notably, CTS affected the digestibility of WPI by precipitating protein and enzyme, whereas COS altered WPI's digestibility by decreasing or inactivating enzyme activity. The present study offered a solid scientific foundation for the rational formulations of carbohydrates and proteins in food industry. [Display omitted] • Chitosan (CTS) and its oligosaccharide (COS) influenced protein digestibility. • CTS decreased protein digestibility by partially precipitating protein and protease. • COS influenced protein digestibility by decreasing the activity of protease. • The electrostatic interaction occurred between -NH 3 + of CTS and -COO− of protein. [ABSTRACT FROM AUTHOR]

Chitosan (CTS) and chitosan oligosaccharides (COS) have been widely applied in food industry due to their bioactivities and functions. However, CTS and COS with positive charges could interact with proteins, such as whey protein isolate (WPI), influencing their digestion. Interaction among CTS/COS, FUC, and WPI/enzymes was studied by spectroscopy, chromatography, and chemical methods in order to reveal the role of FUC in relieving the inhibition of protein digestibility by CTS/COS and demonstrate the action mechanisms. As shown by the results, the addition of FUC increased degree of hydrolysis (DH) and free protein in the mixture of CTS and WPI to 3.1-fold and 1.8-fold, respectively, while raise DH value and free protein in the mixture of COS and WPI to 6.7-fold and 1.2-fold, respectively. The interaction between amino, carboxyl, sulfate, and hydroxyl groups from carbohydrates and protein could be observed, and notably, FUC could interact with CTS/COS preferentially to prevent CTS/COS from combining with WPI. In addition, the addition of FUC could also relieve the combination of CTS to trypsin, increasing the fluorescence intensity and concentration of trypsin by 83.3 % and 4.8 %, respectively. Thus, the present study demonstrated that FUC could alleviate the inhibitory effect of CTS/COS on protein digestion. [Display omitted] • FUC alleviated the negative impact of CTS and COS on protein digestibility. • CTS/COS interacted with FUC preferentially and thus WPI was released. • Electrostatic interaction occurred between -NH 3 + of CTS/COS and -SO 4 2− of FUC. • FUC could hinder the combination of CTS and trypsin. [ABSTRACT FROM AUTHOR]

Excessive protein consumption (EPC) could increase the gastrointestinal burden and impair gut motility. The present study was designed to explore the improvement of chitosan (CTS) and chitosan oligosaccharide (COS) on colonic motility and serum metabolites in rats after EPC. The results of in vivo experiments fully proved that CTS and COS could improve gut motility and reverse the serum metabolites in rats as indicated by LC-MS/MS analysis, and the COS group even showed a better effect than the CTS group. Furthermore, short-chain fatty acids (SCFAs), which could promote gut motility, were also increased to alleviate EPC-induced constipation after supplementation with CTS or COS. In addition, CTS and COS could decrease the concentration of ammonia in serum and down-regulate the levels of H 2 S and indole. In summary, the present study revealed that CTS and COS could produce SCFAs, improve the colonic motility in rats, reverse the levels of valine, adenosine, cysteine, 1-methyladenosine, indole, and uracil, and enhance aminoacyl-tRNA biosynthesis and valine, leucine and isoleucine degradation. The present study provides novel insights into the potential roles of CTS and COS in alleviating the adverse effects of EPC. [Display omitted] • COS was superior to CTS in relieving the negative effects of EPC. • The levels of SCFAs were increased by both CTS and COS to improve colonic motility. • CTS and COS reversed the changes in serum metabolite profiles caused by EPC. • Both CTS and COS decreased the levels of serum ammonia, H 2 S, and indole. [ABSTRACT FROM AUTHOR]

In the present study, a fucoidan fraction (ANP-3) was isolated from Ascophyllum nodosum , and the combined application of desulfation, methylation, HPGPC, HPLC-MSn, FT-IR, GC–MS, NMR, and Congo red test elucidated ANP-3 (124.5 kDa) as a triple-helical sulfated polysaccharide constituted by →2)-α-Fuc p 3 S -(1→, →3)-α-Fuc p 2 S 4 S -(1→, →3,6)-β-Gal p 4 S -(1→, →3,6)-β-Man p 4 S -(1→, →3,6)-β-Gal p 4 S -(1→，→6)-β-Man p -(1→, →3)-β-Gal p -(1→, α-Fuc p -(1→, and α-GlcA p -(1→ residues. To better understand the relationship between the fucoidan structure of A. nodosum and protective effects against oxidative stress, two fractions ANP-6 and ANP-7 were used as contrast. ANP-6 (63.2 kDa) exhibited no protective effect against H 2 O 2 -induced oxidative stress. However, ANP-3 and ANP-7 with the same molecular weight of 124.5 kDa could protect against oxidative stress by down-regulating reactive oxygen species (ROS) and malondialdehyde (MDA) levels and up-regulating total antioxidant capability (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities. Then metabolites analysis indicated that arginine biosynthesis and phenylalanine, tyrosine, and tryptophan biosynthesis metabolic pathways and metabolic biomarkers such as betaine were involved in the effects of ANP-3 and ANP-7. The better protective effect of ANP-7 compared to that of ANP-3 could be attributed to its relatively higher molecular weight, sulfate substitution and →6)-β-Gal p -(1→ content, and lower uronic acid content. [Display omitted] • The ANP-3 backbone mainly consisted of →3)-α-Fuc p 2 S 4 S -(1→ and →2)-α-Fuc p 3 S -(1→. • ANP-3 and ANP-7 with higher-MWs could reduce oxidative stress while ANP-6 could not. • ANP-3 and ANP-7 inhibited oxidative stress by modulating arginine biosynthesis. • ANP-7 with high sulfate content and molecular weight exhibited a stronger effect. [ABSTRACT FROM AUTHOR]

In the present study, two polysaccharides, SVP2–1 and SVP2–2, were isolated from Patinopecten yessoensis viscera and purified by using DEAE-52 cellulose and Sepharose CL-6B. Both SVP2–1 and SVP2–2 could extend activated partial thromboplastin time (APTT) and thrombin time (TT) and inhibit the transformation of fibrinogen into fibrin (FIB) concentration-dependently, indicating they inhibited clotting and thrombin through intrinsic and common pathways. Of note, SVP2–2 had stronger anticoagulant activity than SVP2–1, and its backbone was determined as →6)-α-Man p (1 → 2)-α-Gal p (1 → with Xyl or Glc substituted at C4 of Gal. Based on monosaccharide composition analysis, methylation analysis, and NMR analysis. Further comparison of their monosaccharide analysis and NMR spectra indicates SVP2–1 and SVP2–2 possess the same core structure features, so the higher sulfate content and lower molecular weight may be the possible reasons for the stronger anticoagulant capability of SVP2–2. The present study suggests acidic polysaccharides from scallop viscera as promising anticoagulant candidates. • Two polysaccharides from scallop viscera were purified and characterized. • They inhibited clotting and thrombin through intrinsic and common pathways. • SVP2–2 with higher sulfate content exhibited stronger anticoagulant effect. • The backbone of SVP2–2 was →6)-α-Man(1 → 2)-α-Gal(1 → with Xyl and Glc at C-4 of Gal. [ABSTRACT FROM AUTHOR]

Cyclina sinensis is an edible clam widely distributed along the coastal waters of Asia. In the present study, a polysaccharide (CSP-1) isolated from C. sinensis was purified by a DEAE-Sepharose Fast Flow column, and it had an average molecular weight of 3.8 × 105 Da and a prevalent component monosaccharide of Glc. The results of methylation analysis and 1D/2D NMR indicated that CSP-1 was a glycogen constructed with α-1,4-Glc and branched at C-6 every 9 Glc residues. In addition, Cong red test suggests CSP-1 was not a helical conformation, and irregular and spherical lumps were observed by AFM. Moreover, CSP-1 was found to possess potent immunostimulatory activity on the basis of its significant abilities to enhance NO production and cytokines (TNF-α, IL-1β and IL-6) secretion in RAW 264.7 macrophages. [ABSTRACT FROM AUTHOR]