In vitro angiotensin‑converting enzyme and dipeptidyl peptidase‑IV inhibitory, and antioxidant activity of blue mussel (Mytilus edulis) byssus collagen hydrolysates

Large quantities of mussel byssus are generated annually as a co-product of the mussel-processing industry. This fibrous material is a rich source of collagen, which when extracted has potential uses as an alternative source of collagen for food applications. However, due the complex structure of the material, the extraction of the collagenous components using food-friendly strategies has proved challenging to date. An enzyme-aided method, using a proline endoproteinase, was employed for the extraction of collagen from mussel byssus yielding 138.82±2.25 mg collagen/g dry weight. Hydrolysates of the collagen extract were generated using five food-grade enzyme preparations with Corolase® PP giving the highest extent of hydrolysis. Reversed-phase and gel permeation high-performance liquid chromatography of the extracted collagen and its enzymatic hydrolysates showed significant hydrolysis of collagen. The hydrolysates generated with Corolase® PP showed the highest in vitro bioactivities: angiotensin-converting enzyme (ACE) IC50=0.79±0.17 mg/ml, dipeptidyl peptidase-IV (DPP-IV) IC50=0.66±0.17 mg/ml and oxygen radical absorbance capacity (ORAC) activity=311.23±13.41 µmol trolox equivalents (TE)/g. The results presented herein indicate that in addition to acting as an alternative source of collagen for food applications, mussel byssus collagen-derived hydrolysates have potential applications as functional food ingredients for the management of metabolic diseases such as type II diabetes and hypertension

Blue whiting protein hydrolysates exhibit antioxidant and immunomodulatory activities in stimulated murine RAW264.7 cells

This study investigated the antioxidant and immunomodulatory potential of six blue whiting soluble protein hydrolysates (BWSPHs, BW-SPH-A to -F) and their simulated gastro-intestinal digests (SGID, BW-SPH-A-GI to -F-GI) in murine RAW264.7 macrophages. Hydrolysate BW-SPH-A, both pre- and post-SGID, increased endogenous antioxidant glutathione (GSH) in tert-butylhydroperoxide (tBOOH)-treated cells and reduced reactive oxygen species (ROS) in H2O2 -challenged RAW264.7 cells compared with treated controls in the absence of BWSPHs (p < 0.05). BW-SPH-A-GI also exhibited higher ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) activities than the other BWSPHs tested (p < 0.05). All BWSPHs and SGID BWSPH samples induced immuno stimulating effects in lipopolysaccharide (LPS)-activated RAW264.7 macrophages through the upregulation of NO production. BW-SPH-F-GI increased IL-6 and TNF-α levels compared with the LPS controls indicating the liberation of immunomodulatory peptide/amino acids during the SGID process. Therefore, BW-SPH-A and BW-SPH-F may have potential use against oxidative stress and immunosuppression-related diseases, respectively

A narrative review of the anti-hyperglycemic and satiating effects of fish protein hydrolysates and their bioactive peptides

Prevalence of type 2 diabetes and overweight/obesity are increasing globally. Food supplementation as a preventative option has become an attractive option in comparison to increased pharmacotherapy dependency. Hydrolysates of fish processing waste and by-products have become particularly interesting in a climate of increased food wastage awareness and are rapidly gaining traction in food research. This review summarizes the available research so far on the potential effect of these hydrolysates on diabetes and appetite suppression. Scopus and Web of Science are searched using eight keywords (fish, hydrolysate, peptides, satiating, insulinotropic, incretin, anti-obesity, DPP-4 [dipeptidylpeptidase-4/IV]) returning a total of 2549 results. Following exclusion criteria (repeated appearances, non-fish marine sources [e.g., macroalgae], and irrelevant bioactivities [e.g., immunomodulatory, anti-thrombotic]), 44 relevant publications are included in this review. Stimulation of hormone secretion, regulation of glucose uptake, anorexigenic potential, identified mechanisms of action, and research conducted on the most potent bioactive peptides identified within these hydrolysates are all specifically addressed. Results of this review conclude that despite wide methodological variation between studies, there is significant potential for the application of fish protein hydrolysates in the management of bodyweight and hyperglycemia

Physicochemical, nutritional and in vitro antidiabetic characterisation of blue whiting (micromesistius poutassou) protein hydrolysates

Protein hydrolysates from low-value underutilised fish species are potential sources of high quality dietary protein and health enhancing peptides. Six blue whiting soluble protein hydrolysates (BW-SPH-A_F), generated at industrial scale using different hydrolysis conditions, were assessed in terms of their protein equivalent content, amino acid profile and score and physicochemical properties in addition to their ability to inhibit dipeptidyl peptidase IV (DPP-IV) and stimulate the secretion of insulin from BRIN-BD11 cells. Furthermore, the effect of simulated gastrointestinal digestion (SGID) on the stability of the BW-SPHs and their associated in vitro antidiabetic activity was investigated. The BW-SPHs contained between 70–74% (w/w) protein and all essential and non essential amino acids. All BW-SPHs mediated DPP-IV inhibitory (IC50: 2.12–2.90 mg protein/mL) and insulin secretory activity (2.5 mg/mL; 4.7 to 6.4-fold increase compared to the basal control (5.6 mM glucose alone)). All BW-SPHs were further hydrolysed during SGID. While the in vitro DPP-IV inhibitory and insulin secretory activity mediated by some BW-SPHs was reduced following SGID, the activity remained high. In general, the insulin secretory activity of the BW-SPHs were 4.5–5.4-fold higher than the basal control following SGID. The BW-SPHs generated herein provide potential for anti-diabetic related functional ingredients, whilst also enhancing environmental and commercial sustainability

Twice daily oral administration of Palmaria palmata protein hydrolysate reduces food intake in streptozotocin induced diabetic mice, improving glycaemic control and lipid profiles

This study investigated the antihyperglycaemic effectiveness of an oral Palmaria palmata protein hydrolysate (PPPH), versus metformin, upon metabolic control in streptozotocin (STZ)-induced diabetic mice. Mice were administered PPPH (50 mg/kg bodyweight) or metformin (200 mg/kg bodyweight) by oral gavage twice-daily for 18 days. Blood glucose and plasma insulin were measured every third day. PPPH caused a significant reduction in blood glucose (p < 0.001) and a significant increase in plasma insulin (p < 0.001) versus STZtreated saline controls. PPPH treatment reduced energy intake (p < 0.05), bodyweight (p < 0.01) and total plasma glucagon-like peptide-1 (p < 0.01) after 18 days. Terminal oral glucose tolerance (Day 18, p < 0.05), fasting blood glucose (p < 0.001), HbA1C (p < 0.01), plasma cholesterol (p < 0.01) and plasma triglycerides (p < 0.05) were significantly improved versus STZ-treated saline controls. All groups showed significant increases in pancreatic islet area, β-cell area, and β:α cell ratio. PPPH demonstrated potent antidiabetic potential in vivo through reduced food intake and improved beta-cell function

Enzymatic modification of porphyra dioica-derived proteins to Improve their antioxidant potential

Enzymatic hydrolysis has been employed to modify protein functional properties and discover new sources of antioxidants. In this study, the effect of different enzymatic treatments on antioxidant activity of Porphyra dioica (blades and protein isolate (PI)) was investigated. Protein nitrogen content of P. dioica blades and PI were 23 and 50% (dry weight), respectively. Blades and PI were hydrolyzed with Prolyve®and Prolyve®plus Flavourzyme®. Peptide profiles and molecular mass distribution of the hydrolysates were investigated. The hydrolysis promoted generation of peptides and low molecular mass components <1 kDa. Antioxidant activity was assessed using ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH ) scavenging, 2,20-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS +) inhibition, and reactive oxygen species scavenging ability, i.e., oxygen radical absorbance capacity (ORAC) and hypochlorous acid (HOCl) scavenging assays. In general, enzymatic hydrolysis of P. dioica blades and PI enhanced the in vitro antioxidant activity. Direct hydrolysis of blades improved ORAC values up to 5-fold (from 610 to 3054 mol Trolox eq./g freeze dried sample (FDS). The simultaneous release of phenolic compounds suggested a potential synergistic activity (ORAC and ABTS + assays). Such hydrolysates may be of value as functional food ingredients

Macroalgal protein hydrolysates from palmaria palmata influence the ‘incretin effect’ in vitro via DPP‑4 inhibition and upregulation of insulin, GLP‑1 and GIP secretion

Purpose This study investigated metabolic benefits of protein hydrolysates from the macroalgae Palmaria palmata, previously shown to inhibit dipeptidylpeptidase-4 (DPP-4) activity in vitro. Methods Previously, Alcalase/Flavourzyme-produced P. palmata protein hydrolysate (PPPH) improved glycaemia and insulin production in streptozotocin-induced diabetic mice. Here the PPPH, was compared to alternative Alcalase, bromelain and Promod-derived hydrolysates and an unhydrolysed control. All PPPH’s underwent simulated gastrointestinal digestion (SGID) to establish oral bioavailability. PPPH’s and their SGID counterparts were tested in pancreatic, clonal BRIN-BD11 cells to assess their insulinotropic efect and associated intracellular mechanisms. PPPH actions on the incretin effect were assessed via measurement of DPP-4 activity, coupled with GLP-1 and GIP release from GLUTag and STC-1 cells, respec tively. Acute in vivo effects of Alcalase/Flavourzyme PPPH administration on glucose tolerance and satiety were assessed in overnight-fasted mice. Results PPPH’s (0.02–2.5 mg/ml) elicited varying insulinotropic efects (p<0.05–0.001). SGID of the unhydrolysed protein control, bromelain and Promod PPPH’s retained, or improved, bioactivity regarding insulin secretion, DPP-4 inhibition and GIP release. Insulinotropic effects were retained for all SGID-hydrolysates at higher PPPH concentrations. DPP-4 inhibitory effects were confrmed for all PPPH’s and SGID counterparts (p<0.05–0.001). PPPH’s were shown to directly influence the incretin effect via upregulated GLP-1 and GIP (p<0.01–0.001) secretion in vitro, largely retained after SGID. Alcalase/Flavourzyme PPPH produced the greatest elevation in cAMP (p<0.001, 1.7-fold), which was fully retained post-SGID. This hydrolysate elicited elevations in intracellular calcium (p<0.01) and membrane potential (p<0.001). In acute in vivo settings, Alcalase/Flavourzyme PPPH improved glucose tolerance (p<0.01–0.001) and satiety (p<0.05–0.001). Conclusion Bioavailable PPPH peptides may be useful for the management of T2DM and obesity

In vitro and In vivo effects of palmaria palmata derived peptides on glucose metabolism

Three synthetic peptides, ILAP, LLAP and MAGVDHI, derived from a Palmaria palmata protein hydrolysate were assessed for their antidiabetic potential in vitro and in vivo. In addition to inhibiting dipeptidyl peptidase-IV in a cell-based in situ assay all three peptides signifcantly increased the half-life of the incretin hormone glucagon-like peptide-1 (GLP-1). ILAP and LLAP mediated a signifcant increase (p<0.001) in insulin secretion from BRIN-BD11 cells compared to the glucose control, while MAGVDHI had no insulinotropic activity at an eqimolar concentration (10–6 M). A signifcant increase in the concentration of cyclic adenosine monophosphate production in BRIN-BD11 cells mediated by ILAP (p<0.001) and LLAP (p<0.01) compared to the basal control, would indicate that insulin secretion may be mediated by membrane based activation. Furthermore, ILAP and LLAP acted as glucose-dependent insulinotropic polypeptide (GIP) secretagogues, stimulating a signifcant increase (p<0.01) in the concentration of GIP released from enteroendocrine STC-1 cells compared to the glucose control. When tested in vivo in healthy male NIH Swiss mice, ILAP and LLAP, mediated a signifcant increase (p<0.01) in plasma insulin and decrease (p<0.05) in blood glucose, respectively, compared to the control. MAGVDHI mediated a signifcant (p<0.001) sustained reduction in food intake in food deprived trained mice. These results demonstrate that the Palmaria palmata peptides studied herein have prospective antidiabetic activity and have the potential to act as agents that can be used alone or in combination with drugs, to aid in the prevention and management of Type 2 diabetes mellitus

Stability to thermal treatment of dipeptidyl peptidase IV (DPP-IV) inhibitory activity of a boarfish (Capros aper) protein hydrolysate when incorporated into tomato-based products

Biofunctional peptide ingredients should retain their stability following standard processing operations in food‐based delivery vehicles. A boarfish protein hydrolysate, exhibiting anti‐diabetic activity was subjected to a range of thermal treatments following incorporation into tomato‐based soup and juice products. The dipeptidyl peptidase‐IV (DPP‐IV) inhibitory activity and peptide profile of the hydrolysate within the products were assessed before and after thermal treatment. The treatments applied had no effect on the DPP‐IV inhibitory activity or peptide profile of the protein hydrolysate. The heat‐treated (90°C x 1 min and 121°C x 42 s) juice‐fortified beverage had microbial counts within the acceptable limits for consumption when stored at 4°C for 30 days. Furthermore, the hydrolysate within the beverage products was resistant to simulated gastrointestinal digestion (SGID) regardless of whether it was heat or non‐heat treated, or stored for 30 days at 4°C. Therefore, tomato‐based beverages are suitable delivery vehicles for biofunctional peptide ingredients

Identification and characterisation of peptides from a boarfish (Capros aper) protein hydrolysate displaying in vitro dipeptidyl peptidase-IV (DPP-IV) inhibitory and insulinotropic activity

Twenty-two novel dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides (with IC50 values <200 µM) and fifteen novel insulinotropic peptides were identified in a boarfish protein hydrolysate generated at semi-pilot scale using Alcalase 2.4L and Flavourzyme 500L. This was achieved by bioassay-driven semi preparative reverse phase-high performance liquid chromatography fractionation, liquid chromatography-mass spectrometry and confirmatory studies with synthetic peptides. The most potent DPP-IV inhibitory peptide (IPVDM) had a DPP-IV half maximal inhibitory concentration (IC50) values of 21.72 ± 1.08 µM in a conventional in vitro and 44.26 ± 0.65 µM in an in situ cell-based (Caco 2) DPP-IV inhibition assay. Furthermore, this peptide stimulated potent insulin secretory activity (1.6 fold increase compared to control) from pancreatic BRIN-BD11 cells grown in culture. The tripeptide IPV exhibited potent DPP-IV inhibitory activity (IC50: 5.61 ± 0.20 µM) comparable to that reported for the known DPP-IV inhibitor IPI (IC50: 5.61 µM). Boarfish proteins contain peptide sequences with potential to play a role in glycaemic management in vivo