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

Enrichment and Quantitation of Dipeptidyl Peptidase IV Inhibitory Peptides in Quinoa upon Systematic Malting

Food-derived peptides with an inhibitory effect on dipeptidyl peptidase IV (DPP-IV) can be used as an additive treatment for type 2 diabetes. The inhibitory potential of food depends on technological protein hydrolysis and gastrointestinal digestion, as the peptides only act after intestinal resorption. The effect of malting as a hydrolytic step on the availability of these peptides in grains has yet to be investigated. In this study, quinoa was malted under systematic temperature, moisture, and time variations. In the resulting malts, the DPP-IV inhibition reached a maximum of 45.02 (±10.28) %, whereas the highest overall concentration of literature-known inhibitory peptides was 4.07 μmol/L, depending on the malting parameters. After in vitro gastrointestinal digest, the inhibition of most malts, as well as the overall concentration of inhibitory peptides, could be increased significantly. Additionally, the digested malts showed higher values in both the inhibition and the peptide concentration than the unmalted quinoa. Concerning the malting parameters, germination time had the highest impact on the inhibition and the peptide concentration after digest. An analysis of the protein sizes before and after malting gave first hints toward the origin of these peptides, or their precursors, in quinoa.

Molecular Mechanistic Insights into Dipeptidyl Peptidase-IV Inhibitory Peptides to Decipher the Structural Basis of Activity

Dipeptidyl peptidase-IV (DPP-IV) inhibiting peptides have attracted increased attention because of their possible beneficial effects on glycemic homeostasis. However, the structural basis underpinning their activities has not been well understood. This study combined computational and in vitro investigations to explore the structural basis of DPP-IV inhibitory peptides. We first superimposed the Xaa-Pro-type peptide-like structures from several crystal structures of DPP-IV ligand-protein complexes to analyze the recognition interactions of DPP-IV to peptides. Thereafter, a small set of Xaa-Pro-type peptides was designed to explore the effect of key interactions on inhibitory activity. The intramolecular interaction of Xaa-Pro-type peptides at the first and third positions from the N-terminus was pivotal to their inhibitory activities. Residue interactions between DPP-IV and residues of the peptides at the fourth and fifth positions of the N-terminus contributed significantly to the inhibitory effect of Xaa-Pro-type tetrapeptides and pentapeptides. Based on the interaction descriptors, quantitative structure-activity relationship (QSAR) studies with the DPP-IV inhibitory peptides resulted in valid models with high R2 values (0.90 for tripeptides; 0.91 for tetrapeptides and pentapeptides) and Q2 values (0.33 for tripeptides; 0.68 for tetrapeptides and pentapeptides). Taken together, the structural information on DPP-IV and peptides in this study facilitated the development of novel DPP-IV inhibitory peptides.

Encapsulation of short-chain bioactive peptides (BAPs) for gastrointestinal delivery: a review

The majority of known peptides with high bioactivity (BAPs) such as antihypertensive, antidiabetic, antioxidant, hypocholesterolemic, anti-inflammatory and antimicrobial actions, are short-chain sequences of less than ten amino acids. These short-chain BAPs of varying natural and synthetic origin must be bioaccessible to be capable of being adsorbed systemically upon oral administration to show their full range of bioactivity. However, in general, in vitro and in vivo studies have shown that gastrointestinal digestion reduces BAPs bioactivity unless they are protected from degradation by encapsulation. This review gives a critical analysis of short-chain BAP encapsulation and performance with regard to the oral delivery route. In particular, it focuses on short-chain BAPs with antihypertensive and antidiabetic activity and encapsulation methods via nanoparticles and microparticles. Also addressed are the different wall materials used to form these particles and their associated payloads and release kinetics, along with the current challenges and a perspective of the future applications of these systems.

Self-Assembled Food Peptides: Recent Advances and Perspectives in Food and Health Applications

Self-assembling peptides are rapidly gaining attention as novel biomaterials for food and biomedical applications. Peptides self-assemble when triggered by physical or chemical factors due to their versatile physicochemical characteristics. Peptide self-assembly, when combined with the health-promoting bioactivity of peptides, can also result in a plethora of biofunctionalities of the biomaterials. This perspective highlights current developments in the use of food-derived self-assembling peptides as biomaterials, bioactive nutraceuticals, and potential dual functioning bioactive biomaterials. Also discussed are the challenges and opportunities in the use of self-assembling bioactive peptides in designing biocompatible, biostable, and bioavailable multipurpose biomaterials.

Mechanistic Study of Novel Dipeptidyl Peptidase IV Inhibitory Peptides from Goat's Milk Based on Peptidomics and In Silico Analysis

Two novel dipeptidyl peptidase IV (DPP-IV) inhibitory peptides (YPF and LLLP) were discovered from goat milk protein by peptidomics, in silico analysis, and in vitro assessment. A total of 698 peptides (<23 AA) were successfully identified by LC-MS/MS from goat milk hydrolysates (hydrolyzed by papaian plus proteinase K). Then, 105 potential DPP-IV inhibitory peptides were screened using PeptideRanker, the ToxinPred tool, Libdock, iDPPIV-SCM, and sequence characteristics. After ADME, physicochemical property evaluation, and a literature search, 12 candidates were efficiently selected and synthesized in vitro for functional validation. Two peptides (YPF and LLLP) were found to exert relatively high in vitro chemical system (IC50 = 368.54 ± 12.97 μM and 213.99 ± 0.64 μM) and in situ (IC50 = 159.46 ± 17.40 μM and 154.96 ± 8.41 μM) DPP-IV inhibitory capacities, and their inhibitory mechanisms were further explored by molecular docking. Our study showed that the formation of strong non-bonding interactions with the core residues from the pocket of DPP-IV (such as ARG358, PHE357, GLU205, TYR662, TYR547, and TYR666) might primarily account for the DPP-IV inhibitory activity of two identified peptides. Overall, the two novel DPP-IV inhibitory peptides rapidly identified in this study can be used as functional food ingredients for the control of diabetes.

Identification, rapid screening, docking mechanism and in vitro digestion stability of novel DPP-4 inhibitory peptides from wheat gluten with ginger protease

To better understand the hypoglycemic potential of wheat gluten (WG), we screened dipeptidyl peptidase IV (DPP-4) inhibitory active peptides from WG hydrolysates. WG hydrolysates prepared by ginger protease were found to have the highest DPP-4 inhibitory activity among the five enzymatic hydrolysates, from which a 1-3 kDa fraction was isolated by ultrafiltration. Further characterization of the fraction with nano-HPLC-MS/MS revealed 1133 peptides. Among them, peptides with P'2 (the second position of the N-terminal) and P2 (the second position of the C-terminal) as proline residues (Pro) accounted for 12.44% and 43.69%, respectively. The peptides including Pro-Pro-Phe-Ser (PPFS), Ala-Pro-Phe-Gly-Leu (APFGL), and Pro-Pro-Phe-Trp (PPFW) exhibited the most potent DPP-4 inhibitory activity with IC50 values of 56.63, 79.45, and 199.82 μM, respectively. The high inhibitory activity of PPFS, APFGL, and PPFW could be mainly attributed to their interaction with the S2 pocket (Glu205 and Glu206) and the catalytic triad (Ser630 and His740) of DPP-4, which adopted competitive, mixed, and mixed inhibitory modes, respectively. After comparative analysis of PPFS, PPFW, and PPF, Ser was found to be more conducive to enhancing the DPP-4 inhibitory activity. Interestingly, peptides with P2 as Pro also exhibited good DPP-4 inhibitory activity. Meanwhile, DPP-4 inhibitory peptides from WG showed excellent stability, suggesting a potential application in type 2 diabetes (T2DM) therapy or in the food industry as functional components.

Glucoregulatory Properties of a Protein Hydrolysate from Atlantic Salmon (Salmo salar): Preliminary Characterization and Evaluation of DPP-IV Inhibition and Direct Glucose Uptake In Vitro

Metabolic disorders are increasingly prevalent conditions that manifest pathophysiologically along a continuum. Among reported metabolic risk factors, elevated fasting serum glucose (FSG) levels have shown the most substantial increase in risk exposure. Ultimately leading to insulin resistance (IR), this condition is associated with notable deteriorations in the prognostic outlook for major diseases, including neurodegenerative diseases, cancer risk, and mortality related to cardiovascular disease. Tackling metabolic dysfunction, with a focus on prevention, is a critically important aspect for human health. In this study, an investigation into the potential antidiabetic properties of a salmon protein hydrolysate (SPH) was conducted, focusing on its potential dipeptidyl peptidase-IV (DPP-IV) inhibition and direct glucose uptake in vitro. Characterization of the SPH utilized a bioassay-guided fractionation approach to identify potent glucoregulatory peptide fractions. Low-molecular-weight (MW) fractions prepared by membrane filtration (MWCO = 3 kDa) showed significant DPP-IV inhibition (IC50 = 1.01 ± 0.12 mg/mL) and glucose uptake in vitro (p ≤ 0.0001 at 1 mg/mL). Further fractionation of the lowest MW fractions (<3 kDa) derived from the permeate resulted in three peptide subfractions. The subfraction with the lowest molecular weight demonstrated the most significant glucose uptake activity (p ≤ 0.0001), maintaining its potency even at a dilution of 1:500 (p ≤ 0.01).

Comprehensive workflow encompassing discovery, verification, and quantification of indicator peptide in snail mucin using LC-quadrupole Orbitrap high-resolution tandem mass spectrometry

Peptidomics analysis was conducted using high-resolution tandem mass spectrometry (MS2) to determine the peptide profile of snail-derived mucin extract (SM). The study was also aimed to identify an indicator peptide and validate a quantification method for this peptide. The peptide profiling and identification were conducted using discovery-based peptidomics analysis employing data-dependent acquisition, whereas the selected peptides were verified and quantified using parallel reaction monitoring acquisition. Among the 16 identified peptides, the selected octapeptide (TEAPLNPK) was quantified via precursor ion ionization (m/z 435.2400), followed by quantification of the corresponding quantifier ion fragment (m/z 639.3824) using MS2. The quantification method was optimized and validated in terms of specificity, linearity, accuracy, precision, and limit of detection/quantification. The validated method accurately quantified the TEAPLNPK content in the SM as 7.5 ± 0.2 μg/g. Our study not only identifies an indicator peptide from SM but also introduces a novel validation method, involving precursor ion ionization and quantification of specific fragments. Our findings may serve as a comprehensive workflow for the monitoring, selection, and quantification of indicator peptides from diverse food resources.

Enzymatic Preparation and Processing Properties of DPP-IV Inhibitory Peptides Derived from Wheat Gluten: Effects of Pretreatment Methods and Protease Types

The choice of appropriate proteases and pretreatment methods significantly influences the preparation of bioactive peptides. This study aimed to investigate the effects of different pretreatment methods on the hydrolytic performance of diverse proteases during the production of dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides derived from wheat and their foaming and emulsion properties. Dry heating, aqueous heating, and ultrasound treatment were employed as pretreatments for the protein prior to the enzymatic hydrolysis of wheat gluten. FTIR analysis results indicated that all pretreatment methods altered the secondary structure of the protein; however, the effects of dry heating treatment on the secondary structure content were opposite to those of aqueous heating and ultrasound treatment. Nevertheless, all three methods enhanced the protein solubility and surface hydrophobicity. By using pretreated proteins as substrates, five different types of proteases were employed for DPP-IV inhibitory peptide production. The analysis of the DPP-IV inhibitory activity, degree of hydrolysis, and TCA-soluble peptide content revealed that the specific pretreatments had a promoting or inhibiting effect on DPP-IV inhibitory peptide production depending on the protease used. Furthermore, the pretreatment method and the selected type of protease collectively influenced the foaming and emulsifying properties of the prepared peptides.

Peptides with biological and technofunctional properties produced by bromelain hydrolysis of proteins from different sources: A review

Bromelains are cysteine peptidases with endopeptidase action (a subfamily of papains), obtained from different parts of vegetable belonging to the Bromeliaceae family. They have some intrinsic medical activity, but this review is focused on their application (individually or mixed with other proteases) to produce bioactive peptides. When compared to other proteases, perhaps due to the fact that they are commercialized as an extract containing several proteases, the hydrolysates produced by this enzyme tends to have higher bioactivities than other common proteases. The peptides and the intensity of their final properties depend on the substrate protein and reaction conditions, being the degree of hydrolysis a determining parameter (but not always positive or negative). The produced peptides may have diverse activities such as antioxidant, antitumoral, antihypertensive or antimicrobial ones, among others or they may be utilized to improve the organoleptic properties of foods and feeds. Evolution of the use of this enzyme in this application is proposed to be based on a more intense direct application of Bromeliaceae extract, without the cost associated to enzyme purification, and the use of immobilized biocatalysts of the enzyme by simplifying the enzyme recovery and reuse, and also making the sequential hydrolysis using diverse proteases possible.

Preparation, identification, activity prediction, and protective effects on IR-HepG2 cells of five novel DPP-IV inhibitory peptides from protein hydrolysate of skipjack tuna dark muscles

To produce peptides with high dipeptidyl peptidase IV (DPP-IV) inhibitory activity, neutrase was selected from five proteases (trypsin, neutrase, pepsin, alcalase and flavor protease) with the highest degree of hydrolysis (DH) (18.23 ± 1.08%) and DPP-IV inhibitory rate (53.35 ± 4.02%) to produce protein hydrolysate (NPH) from the dark muscles of skipjack tuna (Katsuwonus pelamis). Then, NPH-1 was isolated from NPH by gel permeation chromatography and found to possess the highest DPP-IV inhibitory rate (65.12 ± 7.94% at 0.5 mg ml-1) in the separated components (including NPH-1, NPH-2, NPH-3 and NPH-4). Subsequently, the available prediction models of tripeptides and tetrapeptides with the DPP-IV inhibitory rate were established using an artificial neural network (ANN). The RMSE (0.56 and 0.33 for the model established through collected tripeptides and tetrapeptides, respectively) and R2 (0.95 and 0.99 for the model established through collected tripeptides and tetrapeptides, respectively) of the ANN model's parameters were within acceptable limits, indicating that this model is available. Next, the ANN model was applied to predict tripeptides and tetrapeptides from the hydrolysate of skipjack tuna dark muscles, and five peptides (Ala-Pro-Pro (APP), Pro-Pro-Pro (PPP), Asp-Pro-Leu-Leu (DPLL), Glu-Ala-Val-Pro (EAVP) and Glu-Ala-Iie-Pro (EAIP)) possessing a noticeable DPP-IV inhibitory rate (with DPP-IV IC50 values of 42.46 ± 5.02, 37.71 ± 9.17, 58.85 ± 14.42, 49.94 ± 6.69 and 57.15 ± 6.13 μM, respectively) were screened from the protein hydrolysate. The above five peptides were proved to effectively promote glucose consumption in the insulin resistant-HepG2 (IR-HepG2) cell model considering that the glucose consumption rates of APP, PPP, DPLL, EAVP and EAIP treatment groups are all more than twice that of the dexamethasone group. Accordingly, mechanistic studies showed that these peptides interacted with PI3K/AKT and AMPK signaling pathways and promoted the phosphorylation of PI3K p110, AKT and AMPK (the protein expressions of PI3K p110, p-AKT and p-AMPK in APP, PPP, DPLL, EAVP and EAIP treatment groups are 1.64-2.22 fold compared with that in the dexamethasone group), thereby enhancing glucose uptake and further alleviating insulin resistance. These findings demonstrated that skipjack tuna dark muscle is a potential DPP-IV inhibitory peptide source, and five DPP-IV inhibitory peptides from its hydrolysate may exert potent anti-diabetic activity. In comparison, PPP may be the most potential active ingredient for healthy food against type 2 diabetes mellitus in the five screened peptides considering synthetically the DPP-IV inhibitory rate, bioavailability and synthesis cost.

DPP-IV Inhibitory Peptides from Coix Seed Prolamins: Release, Identification, and Analysis of the Interaction between Key Residues and Enzyme Domains

Dipeptidyl peptidase IV (DPP-IV) inhibitory peptides can regulate type 2 diabetes by inhibiting the cleavage of glucagon-like peptide-1 and prolonging its half-life. The development of DPP-IV inhibitory peptides is still a hot topic. The primary structure of coix seed prolamins contains peptide sequence fragments that potentially inhibit DPP-IV; however, limited information is available regarding the extraction of peptides from coix seeds and the analysis of their conformational relationships. In this study, novel coix seed prolamin-derived peptides were obtained through single hydrolysis and double-enzyme stepwise hydrolysis. The inhibitory activity of these peptides against DPP-IV was evaluated to explore new functional properties of coix seeds. The results evidenced that the step-by-step enzymolysis (papain and alcalase) compared to single enzymolysis promoted the secondary structure disruption of the hydrolysates, enhanced the β-turn structure, significantly increased the content of peptides below 1 kDa, and exhibited a substantial increase in DPP-IV inhibitory activity (97% inhibition). Three nontoxic DPP-IV inhibitory peptides, namely, LPFYPN, TFFPQ, and ATFFPQ (IC50 = 70.24, 176.87, 268.31 μM), were isolated and identified. All three peptides exhibited strong interactions with DPP-IV (all KA values >103). LPFYPN exhibited competitive inhibition, while TFFPQ and ATFFPQ demonstrated mixed competitive-noncompetitive inhibition. Hydrogen bonding and hydrophobic interactions were the main contributors to the coix seed prolamin peptides binding to DPP-IV. The central residue was a key amino acid in the parent peptide sequence, forming a more stable π-π stacking with residues in the active pocket, which may facilitate peptide activity. This study provides theoretical support for the development of coix seed-derived hypoglycemic peptides.

Critical Review for the Production of Antidiabetic Peptides by a Bibliometric Approach

The current bibliometric review evaluated recent papers that researched dietary protein sources to generate antidiabetic bioactive peptides/hydrolysates for the management of diabetes. Scopus and PubMed databases were searched to extract bibliometric data and, after a systematic four-step process was performed to select the articles, 75 papers were included in this review. The countries of origin of the authors who published the most were China (67%); Ireland (59%); and Spain (37%). The journals that published most articles on the subject were Food Chemistry (n = 12); Food & Function (n = 8); and Food Research International (n = 6). The most used keywords were ‘bioactive peptides’ (occurrence 28) and ‘antidiabetic’ (occurrence 10). The most used enzymes were Alcalase^® (17%), Trypsin (17%), Pepsin, and Flavourzyme^® (15% each). It was found that different sources of protein have been used to generate dipeptidyl peptidase IV (DPP-IV), α-amylase, and α-glucosidase inhibitory peptides. In addition to antidiabetic properties, some articles (n = 30) carried out studies on multifunctional bioactive peptides, and the most cited were reported to have antioxidant and antihypertensive activities (n = 19 and 17, respectively). The present review intended to offer bibliometric data on the most recent research on the production of antidiabetic peptides from dietary proteins to those interested in their obtention to act as hypoglycemic functional ingredients. The studies available in this period, compiled, are not yet enough to point out the best strategies for the production of antidiabetic peptides from food proteins and a more systematic effort in this direction is necessary to allow a future scale-up for the production of these possible functional ingredients.

Food-derived dipeptidyl peptidase IV inhibitory peptides: Production, identification, structure-activity relationship, and their potential role in glycemic regulation

Dipeptidyl Peptidase IV (DPP-IV) inhibitory peptides are attracting increasing attention, owing to their potential role in glycemic regulation by preventing the inactivation of incretins. However, few reviews have summarized the current understanding of DPP-IV inhibitory peptides and their knowledge gaps. This paper reviews the production, identification and structure-activity relationships (SAR) of DPP-IV inhibitory peptides. Importantly, their bioavailability and hypoglycemic effects are critically discussed. Unlike the traditional method to identifying peptides after separation step by step, the bioinformatics approach identifies peptides via virtual screening that is more convenient and efficient. In addition, the bioinformatics approach was also used to investigate the SAR of peptides. Peptides with proline (Pro) or alanine (Ala) residue at the second position of N-terminal are exhibit strong DPP-IV inhibitory activity. Besides, the bioavailability of DPP-IV inhibitory peptides is related to their gastrointestinal stability and cellular permeability, and in vivo studies showed that the glucose homeostasis has been improved by these peptides. Especially, the intestinal transport of DPP-IV inhibitory peptides and cell biological assays used to evaluate their potential role in glycemic regulation are innovatively summarized. For further successful development of DPP-IV inhibitory peptides in glycemic regulation, future study should elucidate their SAR and in vivo hypoglycemic effects .

In Vivo and In Vitro Comparison of the DPP-IV Inhibitory Potential of Food Proteins from Different Origins after Gastrointestinal Digestion

Dipeptidyl-peptidase IV (DPP-IV) plays an essential role in glucose metabolism by inactivating incretins. In this context, food-protein-derived DPP-IV inhibitors are promising glycemic regulators which may act by preventing the onset of type 2 diabetes in personalized nutrition. In this study, the DPP-IV-inhibitory potential of seven proteins from diverse origins was compared for the first time in vitro and in vivo in rat plasma after the intestinal barrier (IB) passage of the indigested proteins. The DPP-IV-inhibitory potentials of bovine hemoglobin, caseins, chicken ovalbumin, fish gelatin, and pea proteins were determined in rat plasma thirty minutes after oral administration. In parallel, these proteins, together with bovine whey and gluten proteins, were digested using the harmonized INFOGEST protocol adapted for proteins. The DPP-IV half-maximal inhibitory concentration (IC50) was determined in situ using Caco-2 cells. The DPP-IV-inhibitory activity was also measured after IB passage using a Caco2/HT29-MTX mixed-cell model. The peptide profiles were analyzed using reversed-phase high-performance liquid chromatography tandem mass spectrometry (RP-HPLC-MS/MS) with MS data bioinformatics management, and the IC50 of the identified peptides was predicted in silico. The in vitro and in vivo DPP-IV-inhibitory activity of the proteins differed according to their origin. Vegetable proteins and hemoglobin yielded the highest DPP-IV-inhibitory activity in vivo. However, no correlation was found between the in vivo and in vitro results. This may be partially explained by the differences between the peptidome analysis and the in silico predictions, as well as the study complexity.

Identification of the DPP-IV Inhibitory Peptides from Donkey Blood and Regulatory Effect on the Gut Microbiota of Type 2 Diabetic Mice

After being treated with protease K, peptides extracted from donkey blood were separated, identified, and characterized. The results showed that Sephadex G-25 medium purified with MW < 3 kDa had the highest dipeptidyl peptidase IV (DPP-IV) inhibition capacity. Three-hundred-and-thirty-four peptides were identified with UPLC−MS/MS. Peptide Ranker and molecular docking analysis were used to screen active peptides, and 16 peptides were finalized out of the 334. The results showed that the lowest binding energy between P7(YPWTQ) and DPP-IV was −9.1, and the second-lowest binding energy between P1(VDPENFRLL) and DPP-IV was −8.7. The active peptides(MW < 3 kDa) could cause a reduction in the fasting blood glucose levels of type 2 diabetic mice, improve glucose tolerance, and facilitate healing of the damaged structure of diabetic murine liver and pancreas. Meanwhile, the peptides were found to ameliorate the diabetic murine intestinal micro-ecological environment to a certain extent.

Nutrients and Bioactive Compounds in Seafood: Quantitative Literature Research Analysis

This perspective presents current and updated advances in research on nutrients and bioactive compounds in seafood. It is based on a literature quantitative research analysis approach. The main features of seafood components are introduced. This perspective aims at providing a current framework that relates nutrients, bioactive compounds, and seafood in a novel integrated and multidisciplinary manner, highlighting the current knowledge, the main research lines, and emerging strategies. The literature search was carried out by means of the Scopus database, and 22,542 documents were retrieved in the period from 1932 to 2024. Particularly, from the perspective of nutrition and health outputs, the main terms correlated with research on the relationship between seafood and nutritional and bioactive components, and the main existing research lines focused on this topic, were identified. The top recurring keywords were human/s, female, diet, nutrition, fish, male, adult, food intake.

Bioactive Peptides: An Understanding from Current Screening Methodology

Bioactive peptides with high potency against numerous human disorders have been regarded as a promising therapy in disease control. These peptides could be released from various dietary protein sources through hydrolysis processing using physical conditions, chemical agents, microbial fermentation, or enzymatic digestions. Considering the diversity of the original proteins and the complexity of the multiple structural peptides that existed in the hydrolysis mixture, the screening of bioactive peptides will be a challenge task. Well-organized and well-designed methods are necessarily required to enhance the efficiency of studying the potential peptides. This article, hence, provides an overview of bioactive peptides with an emphasis on the current strategy used for screening and characterization methods. Moreover, the understanding of the biological activities of peptides, mechanism inhibitions, and the interaction of the complex of peptide–enzyme is commonly evaluated using specific in vitro assays and molecular docking analysis.

A comprehensive review on the glucoregulatory properties of food-derived bioactive peptides

Diabetes mellitus, a group of metabolic disorders characterized by persistent hyperglycemia, affects millions of people worldwide and is on the rise. Dietary proteins, from a wide range of food sources, are rich in bioactive peptides with antidiabetic properties. Notable examples include AGFAGDDAPR, a black tea-derived peptide, VRIRLLQRFNKRS, a β-conglycinin-derived peptide, and milk-derived peptide VPP, which have shown antidiabetic effects in diabetic rodent models through variety of pathways including improving beta-cells function, suppression of alpha-cells proliferation, inhibiting food intake, increasing portal cholecystokinin concentration, enhancing insulin signaling and glucose uptake, and ameliorating adipose tissue inflammation. Despite the immense research on glucoregulatory properties of bioactive peptides, incorporation of these bioactive peptides in functional foods or nutraceuticals is widely limited due to the existence of several challenges in the field of peptide research and commercialization. Ongoing research in this field, however, is fundamental to pave the road for this purpose.

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.

In vitro dipeptidyl peptidase IV inhibitory activity and in situ insulinotropic activity of milk and egg white protein digests

Dietary proteins are involved in the regulation of glucose homeostasis by different mechanisms. Food protein digestion products are reported to inhibit dipeptidyl peptidase IV (DPP-IV), induce incretin secretion or directly exert an insulinotropic effect in pancreatic β-cells. This study illustrates the DPP-IV inhibitory activity of gastric and intestinal digests of casein, whey and egg white proteins determined in vitro, using Gly-Pro-AMC, and in situ using non-differentiated Caco-2 cells. Comparable trends in the DPP-IV inhibitory profiles were obtained by these two methods although the extent of inhibition in situ was consistently lower than the inhibition observed in vitro. Casein intestinal digests and whey protein gastric and intestinal digests showed potent DPP-IV inhibitory activities in Caco-2 cells with IC₅₀ values ranging from 0.8 to 1.2 mg mL^-1. The absorbed fraction of the intestinal digests from whey and egg white protein induced insulin secretion in BRIN-BD11 cells when determined using a two-tiered cellular model (Caco-2 and BRIN-BD11). However, the gastric digests from the same substrates showed no insulin secretion. This may be related to limited trans-epithelial transport through the Caco-2 monolayer of the gastric digestion products. However, both, gastric and intestinal digests were able to induce insulin secretion in BRIN-BD11 cells when the monolayer was composed of a co-culture of STC-1 and Caco-2 cells. This result may be attributed to the activation of STC-1 cells and subsequent incretin secretion, induced by the gastric digest, as shown by an enhanced intracellular calcium uptake.

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 effect 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, respectively. 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 effects (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 confirmed 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.

Purification, identification and molecular mechanism of dipeptidyl peptidase IV inhibitory peptides from discarded shrimp (Penaeus vannamei) head

DPP-IV plays a key role for regulation of glucose metabolism in the body. The object of this study was to obtain DPP-IV inhibitors from discarded but protein-rich Penaeus vannamei (P. vannamei) head, and to explore the potential mechanism between DPP-IV and its inhibitors. P. vannamei head protein was hydrolyzed by five food grade proteases, respectively. The animal protease hydrolysate showed the highest inhibitory active. Then the hydrolysate was sequentially separated by ultrafiltration, gel filtration chromatography and reversed phase high-performance liquid chromatography (RP-HPLC), the peptides sequences were identified by LC-MS/MS and four potential peptides YPGE, VPW, HPLY, YATP showed superior DPP-IV inhibitory activity. Meanwhile, molecular docking effectively explored their mechanism through formed hydrogen bonds and hydrophobic regions. The four peptides showed better DPP-IV inhibitory activity stability with heating treatment, pH (1-10) treatment, and in vitro gastrointestinal digestion. Our results demonstrated that the protein hydrolysate from discarded P. vannamei head can be considered as a promising natural source of DPP-IV inhibitor for helping to improve glycaemic control in Type 2 diabetes.

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 significantly increased the half-life of the incretin hormone glucagon-like peptide-1 (GLP-1). ILAP and LLAP mediated a significant 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 significant 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 significant 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 significant increase (p < 0.01) in plasma insulin and decrease (p < 0.05) in blood glucose, respectively, compared to the control. MAGVDHI mediated a significant (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.

Characteristics of Food Protein-Derived Antidiabetic Bioactive Peptides: A Literature Update

Diabetes, a glucose metabolic disorder, is considered one of the biggest challenges associated with a complex complication of health crises in the modern lifestyle. Inhibition or reduction of the dipeptidyl peptidase IV (DPP-IV), alpha-glucosidase, and protein-tyrosine phosphatase 1B (PTP-1B) enzyme activities or expressions are notably considered as the promising therapeutic strategies for the management of type 2 diabetes (T2D). Various food protein-derived antidiabetic bioactive peptides have been isolated and verified. This review provides an overview of the DPP-IV, PTP-1B, and α-glucosidase inhibitors, and updates on the methods for the discovery of DPP-IV inhibitory peptides released from food-protein hydrolysate. The finding of novel bioactive peptides involves studies about the strategy of separation fractionation, the identification of peptide sequences, and the evaluation of peptide characteristics in vitro, in silico, in situ, and in vivo. The potential of bioactive peptides suggests useful applications in the prevention and management of diabetes. Furthermore, evidence of clinical studies is necessary for the validation of these peptides’ efficiencies before commercial applications.

Engineering Concanavalin B to Release Bioactive Peptides against Metabolic Syndrome

Metabolic syndrome is a severe public health issue characterized by multiple metabolic disturbances. Current treatments prescribe a particular drug for each of them, producing multiple side effects. As a first step towards a more integral approach, we applied our recently described methodology to design single proteins, based in the Concanavalin B scaffold (1CNV), that contain several bioactive peptides (BPs), including antioxidant and lipid-lowering activities as well as inhibitors of dipeptidyl peptidase IV (DPPIV) and the angiotensin converting enzyme. Modified Concanavalin (CNV44), the designed protein that showed the best in silico properties, was expressed in high yields in E. coli and purified to homogeneity. After in vitro digestion with gastrointestinal enzymes, all the biological activities tested where higher in CNV44 when compared to the non-modified protein 1CNV, or to other previous reports. The results presented here represent the first in vitro evidence of a modified protein with the potential to treat metabolic syndrome and open the venue for the design of proteins to treat other non-communicable diseases.

Physicochemical, Nutritional and In Vitro Antidiabetic Characterisation of Blue Whiting (Micromesistiuspoutassou) 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.

Dipeptidyl Peptidase (DPP)-IV Inhibitors with Antioxidant Potential Isolated from Natural Sources: A Novel Approach for the Management of Diabetes

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia that is predominantly caused by insulin resistance or impaired insulin secretion, along with disturbances in carbohydrate, fat and protein metabolism. Various therapeutic approaches have been used to treat diabetes, including improvement of insulin sensitivity, inhibition of gluconeogenesis, and decreasing glucose absorption from the intestines. Recently, a novel approach has emerged using dipeptidyl peptidase-IV (DPP-IV) inhibitors as a possible agent for the treatment of T2DM without producing any side effects, such as hypoglycemia and exhaustion of pancreatic β-cells. DPP-IV inhibitors improve hyperglycemic conditions by stabilizing the postprandial level of gut hormones such as glucagon-like peptide-1, and glucose-dependent insulinotropic polypeptides, which function as incretins to help upregulate insulin secretion and β-cell mass. In this review, we summarized DPP-IV inhibitors and their mechanism of inhibition, activities of those isolated from various natural sources, and their capacity to overcome oxidative stress in disease conditions.

Roles of Dietary Bioactive Peptides in Redox Balance and Metabolic Disorders

Bioactive peptides (BPs) are fragments of 2-15 amino acid residues with biological properties. Dietary BPs derived from milk, egg, fish, soybean, corn, rice, quinoa, wheat, oat, potato, common bean, spirulina, and mussel are reported to possess beneficial effects on redox balance and metabolic disorders (obesity, diabetes, hypertension, and inflammatory bowel diseases (IBD)). Peptide length, sequence, and composition significantly affected the bioactive properties of dietary BPs. Numerous studies have demonstrated that various dietary protein-derived BPs exhibited biological activities through the modulation of various molecular mechanisms and signaling pathways, including Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2/antioxidant response element in oxidative stress; peroxisome proliferator-activated-γ, CCAAT/enhancer-binding protein-α, and sterol regulatory element binding protein 1 in obesity; insulin receptor substrate-1/phosphatidylinositol 3-kinase/protein kinase B and AMP-activated protein kinase in diabetes; angiotensin-converting enzyme inhibition in hypertension; and mitogen-activated protein kinase and nuclear factor-kappa B in IBD. This review focuses on the action of molecular mechanisms of dietary BPs and provides novel insights in the maintenance of redox balance and metabolic diseases of human.

Recent developments on production, purification and biological activity of marine peptides

Marine peptides are one of the richest sources of structurally diverse bioactive compounds and a considerable attention has been drawn towards their production and bioactivity. However, there is a paucity in consolidation of emerging trends encompassing both production techniques and biological application. Herein, we intend to review the recent advancements on different production, purification and identification technologies used for marine peptides along with presenting their potential health benefits. Bibliometric analysis revealed a growing number of scientific publications on marine peptides (268 documents per year) with both Asia (37.2%) and Europe (33.1%) being the major contributors. Extraction and purification by ultrafiltration and enzymatic hydrolysis, followed by identification by chromatographic techniques coupled with an appropriate detector could yield a high content of peptides with improved bioactivity. Moreover, the multifunctional health benefits exerted by marine peptides including anti-microbial, antioxidant, anti-hypertension, anti-diabetes and anti-cancer along with their structure-activity relationship were presented. The future perspective on marine peptide research should focus on finding improved separation and purification technologies with enhanced selectivity and resolution for obtaining more novel peptides with high yield and low cost. In addition, by employing encapsulation strategies such as nanoemulsion and nanoliposome, oral bioavailability and bioactivity of peptides can be greatly enhanced. Also, the potential health benefits that are demonstrated by in vitro and in vivo models should be validated by conducting human clinical trials for a technology transfer from bench to bedside.

New Bioactive Peptides Identified from a Tilapia Byproduct Hydrolysate Exerting Effects on DPP-IV Activity and Intestinal Hormones Regulation after Canine Gastrointestinal Simulated Digestion

Like their owners, dogs and cats are more and more affected by overweight and obesity-related problems and interest in functional pet foods is growing sharply. Through numerous studies, fish protein hydrolysates have proved their worth to prevent and manage obesity-related comorbidities like diabetes. In this work, a human in vitro static simulated gastrointestinal digestion model was adapted to the dog which allowed us to demonstrate the promising effects of a tilapia byproduct hydrolysate on the regulation of food intake and glucose metabolism. Promising effects on intestinal hormones secretion and dipeptidyl peptidase IV (DPP-IV) inhibitory activity were evidenced. We identify new bioactive peptides able to stimulate cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) secretions, and to inhibit the DPP-IV activity after a transport study through a Caco-2 cell monolayer.

Anti-diabetic effects of bioactive peptides: recent advances and clinical implications

Diabetes mellitus, particularly type 2 diabetes, is a major global health issue, the prevalence of which seems to be on the rise worldwide. Interventions such as healthy diet, physical activity, maintaining a healthy weight, and medication (for those with a diagnosis of diabetes) are among the most effective strategies to prevent and control diabetes. Three-quarters of patients diagnosed with diabetes are in countries with poor financial infrastructure, nutritional awareness and health care systems. Concomitantly, the cost involved in managing diabetes through the intake of antidiabetic drugs makes it prohibitive for majority of patients. Food protein-derived bioactive peptides have the potential of being formulated as nutraceuticals and drugs in combating the pathogenesis and pathophysiology of metabolic disorders with little or "no known" complications in humans. Coupled with lifestyle modifications, the potential of bioactive peptides to maintain normoglycemic range is actualized by influencing the activities of incretins, DPP-IV, α-amylase, and α-glucosidase enzymes. This article discusses the biofunctionality and clinical implications of anti-diabetic bioactive peptides in controlling the global burden of diabetes.

Amaranth, quinoa and chia bioactive peptides: a comprehensive review on three ancient grains and their potential role in management and prevention of Type 2 diabetes

Worldwide prevalence of Type 2 Diabetes (T2D) has become a major concern with several implications for public health, economy, and social well-being, especially in developing countries. Conventional pharmacological management of T2D have proved effective, but possess underlying side effects, leading the scientific community to research alternative compounds that exert beneficial effects on current therapeutic targets of T2D. Bioactive peptides (BAPs) from food sources, have shown relative advantages in this matter, moreover, BAPs have proved to impart anti-diabetic activity through one or more mechanisms such as enzymatic inhibition of α-glucosidase, α-amylase and DPP-IV. Several plants and animal have been used as protein sources of anti-diabetic BAPs, in the sense of this matter, the pseudo-cereals amaranth and quinoa, along with the ancestral grain chia, have gained attention. Due, to their high protein content and balanced amino-acid composition, along with proved anti-diabetic features, the three seeds are top choices for the obtention of anti-diabetic BAPs. With a comprehensive overview of the most recent reported in silico and in vitro anti-diabetic studies in relation to biomarkers α-glucosidase, α-amylase and DPP-IV, the present review aims to examine the current knowledge of amaranth, quinoa and chia derived anti-diabetic BAPs and their effects on T2D therapeutic markers.

Use of Alcalase in the production of bioactive peptides: A review

This review aims to cover the uses of the commercially available protease Alcalase in the production of biologically active peptides since 2010. Immobilization of Alcalase has also been reviewed, as immobilization of the enzyme may improve the final reaction design enabling the use of more drastic conditions and the reuse of the biocatalyst. That way, this review presents the production, via Alcalase hydrolysis of different proteins, of peptides with antioxidant, angiotensin I-converting enzyme inhibitory, metal binding, antidiabetic, anti-inflammatory and antimicrobial activities (among other bioactivities) and peptides that improve the functional, sensory and nutritional properties of foods. Alcalase has proved to be among the most efficient proteases for this goal, using different protein sources, being especially interesting the use of the protein residues from food industry as feedstock, as this also solves nature pollution problems. Very interestingly, the bioactivities of the protein hydrolysates further improved when Alcalase is used in a combined way with other proteases both in a sequential way or in a simultaneous hydrolysis (something that could be related to the concept of combi-enzymes), as the combination of proteases with different selectivities and specificities enable the production of a larger amount of peptides and of a smaller size.

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.

Antidiabetic Food-Derived Peptides for Functional Feeding: Production, Functionality and In Vivo Evidences

Bioactive peptides released from the enzymatic hydrolysis of food proteins are currently a trending topic in the scientific community. Their potential as antidiabetic agents, by regulating the glycemic index, and thus to be employed in food formulation, is one of the most important functions of these peptides. In this review, we aimed to summarize the whole process that must be considered when talking about including these molecules as a bioactive ingredient. In this regard, at first, the production, purification and identification of bioactive peptides is summed up. The detailed metabolic pathways described included carbohydrate hydrolases (glucosidase and amylase) and dipeptidyl-peptidase IV inhibition, due to their importance in the food-derived peptides research field. Then, their characterization, concerning bioavailability in vitro and in situ, stability and functionality in food matrices, and ultimately, the in vivo evidence (from invertebrate animals to humans), was described. The future applicability that these molecules have due to their biological potential as functional ingredients makes them an important field of research, which could help the world population avoid suffering from several diseases, such as diabetes.

Evaluation of Tenebrio molitor protein as a source of peptides for modulating physiological processes

The increasing world population has led to the need to search for new protein sources, such as insects, the harvesting of which can be economical and environmentally sustainable. This study explores the biological activities (angiotensin-converting enzyme (ACE) inhibition, antioxidant capacity, and dipeptidyl peptidase IV (DPP-IV) inhibition) of Tenebrio molitor hydrolysates produced by a set of food-grade proteases, namely subtilisin, trypsin, ficin and flavourzyme, and the degree of hydrolysis (DH), ranging from 5% to 20%. Trypsin hydrolysates exhibited the highest ACE inhibitory activity at a DH of 10% (IC₅₀ 0.27 mg mL^-1) in the experimental series, which was attributed to the release of short peptides containing Arg or Lys residues in the C terminus, and described as the ACE-inhibition feature. The levels of in vitro antioxidant activities were comparable to those reported for insect species. Subtilisin and trypsin hydrolysates at a DH of 10% displayed optimal DPPH scavenging and ferric reducing activities, which was attributed to the presence of 5-10-residue active peptides, as reported in the literature. Iron chelating activity was significantly favoured by increasing the DH, attaining a minimal IC₅₀ of 0.8 mg mL^-1 at a DH of 20% regardless of the enzymatic treatment. Similarly, in vitro antidiabetic activity was significantly improved by extensive hydrolysis, and, more specifically, the presence of di- and tripeptides. In this regard, the combined treatment of subtilisin-flavourzyme at a DH of 20% showed maximal DPP-IV inhibition (IC₅₀ 2.62 mg mL^-1). To our knowledge, this is the first study evaluating the DPP-IV activity of Tenebrio molitor hydrolysates obtained from these commercial proteases. We conclude that Tenebrio molitor hydrolysates produced with food-grade proteases are a valuable source of active peptides that can be used as functional ingredients in food and nutraceutical preparations.