Effect of Amine, Carboxyl, or Thiol Functionalization of Mesoporous Silica Particles on Their Efficiency as a Quercetin Delivery System in Simulated Gastrointestinal Conditions

Quercetin (Q) dietary supplements exhibit poor oral bioavailability because of degradation throughout gastrointestinal digestion (GD), which may be overcome using mesoporous silica particles (MSPs) as an oral delivery system (ODS). This study aimed to elucidate the effect of the functionalization of MSPs with amine-(A-MSP), carboxyl-(C-MSP), or thiol-(T-MSP) groups on their efficiency as a quercetin ODS (QODS). The type and degree of functionalization (DF) were used as factors in an experimental design. The Q-loaded F-MSP (F-MSP/Q) was characterized by gas physisorption analysis, loading capacity (LC), and dynamic light scattering and kinetics of Q release at gastric and intestinal pHs. Antioxidant capacity and Q concentration of media containing F-MSP/Q were evaluated after simulated GD. A-MSP showed the highest LC (19.79 ± 2.42%). C-MSP showed the lowest particle size at pH 1.5 or 7.4 (≈200 nm). T-MSP exhibited the maximum Q release at pH 7.4 (11.43%). High DF of A-MSP increased Q retention, regardless of pH. A-MSP preserved antioxidant capacity of Q-released gastric media (58.95 ± 3.34%). Nonetheless, MSP and F-MSP did not protect antioxidant properties of Q released in intestinal conditions. C-MSP and T-MSP showed essential features for cellular uptake and Q release within cells that need to be assessed.

Bio-functional and prebiotics properties of products based on whole grain sorghum fermented with lactic acid bacteria

BACKGROUND

Products fermented with lactic acid bacteria based on whole grain flours of red or white sorghum (Sorghum bicolor (L.) Moench) added with malted sorghum flour, or with skim milk (SM) were developed. Composition, protein amino acid profile, total acidity, pH, prebiotic potential, and bio-functional properties after simulation of gastrointestinal digestion were evaluated.

RESULTS

In all cases, a pH of 4.5 was obtained in approximately 4.5 h. The products added with SM presented higher acidity. Products made only with sorghum presented higher total dietary fiber, but lower protein content than products with added SM, the last ones having higher lysine content. All products exhibited prebiotic potential, white sorghum being a better ingredient to promote the growth of probiotic bacteria. The addition of malted sorghum or SM significantly increased the bio-functional properties of the products: the sorghum fermented products added with SM presented the highest antioxidant (ABTS•+ inhibition, 4.7 ± 0.2 mM Trolox), antihypertensive (Angiotensin converting enzyme-I inhibition, 57.3 ± 0.5%) and antidiabetogenic (dipeptidyl-peptidase IV inhibition, 31.3 ± 2.1%) activities, while the products added with malted sorghum presented the highest antioxidant (reducing power, 1.6 ± 0.1 mg ascorbic acid equivalent/mL) and antidiabetogenic (α-amylase inhibition, 38.1 ± 0.9%) activities.

CONCLUSION

The fermented whole grain sorghum-based products could be commercially exploited by the food industry to expand the offer of the three high-growth markets: gluten-free products, plant-based products (products without SM), and functional foods. © 2023 Society of Chemical Industry.

Impact of Whey Protein Corona Formation around TiO2 Nanoparticles on Their Physiochemical Properties and Gastrointestinal Fate

Previously, we found that whey proteins form biomolecular coronas around titanium dioxide (TiO2) nanoparticles. Here, the gastrointestinal fate of whey protein-coated TiO2 nanoparticles and their interactions with gut microbiota were investigated. The antioxidant activity of protein-coated nanoparticles was enhanced after simulated digestion. The structure of the whey proteins was changed after they adsorbed to the surfaces of the TiO2 nanoparticles, which reduced their hydrolysis under simulated gastrointestinal conditions. The presence of protein coronas also regulated the impact of the TiO2 nanoparticles on colonic fermentation, including promoting the production of short-chain fatty acids. Bare TiO2 nanoparticles significantly increased the proportion of harmful bacteria and decreased the proportion of beneficial bacteria, but the presence of protein coronas alleviated this effect. In particular, the proportion of beneficial bacteria, such as Bacteroides and Bifidobacterium, was enhanced for the coated nanoparticles. Our results suggest that the formation of a whey protein corona around TiO2 nanoparticles may have beneficial effects on their behavior within the colon. This study provides valuable new insights into the potential impact of protein coronas on the gastrointestinal fate of inorganic nanoparticles.

Alterations in the sequence and bioactivity of food-derived oligopeptides during simulated gastrointestinal digestion and absorption: a review

Food-derived oligopeptides (FOPs) exhibit various bioactivities. However, little was known about their sequence changes in the gastrointestinal tract and the effect of changes on bioactivities. FOPs' sequence features, changes and effects on bioactivities have been summarised. The sequence length of FOPs decreases with increased exposure of hydrophobic and basic amino acids at the terminal during simulated gastrointestinal digestion. A decrease in bioactivities after simulated intestinal absorption has correlated with a decrease of Leu, Ile, Arg, Tyr, Gln and Pro. The sequence of FOPs that pass readily through the intestinal epithelium corresponds to transport modes, and FOPs whose sequences remain unchanged after transport are the most bioactive. These include mainly dipeptides to tetrapeptides, consisting of numerous hydrophobic and basic amino acids, found mostly at the end of the peptide chain, especially at the C-terminal. This review aims to provide a foundation for applications of FOPs in nutritional supplements and functional foods.

Alginate beads loaded with rambutan extract: characterization and stability during in vitro gastrointestinal digestion

BACKGROUND

Fallen young rambutan fruit is an underrated agricultural waste which may contain several bioactive compounds. In this study, fallen young rambutan fruit was assessed regarding its phenolic contents and antioxidant activities. In order to expand its utilization, rambutan extract-loaded hydrogel beads were developed by a basic spherification technique using sodium alginate. The effect of ratios of polymer and extract and different calcium sources were evaluated. The recovery of bioactive compounds from the hydrogel beads was determined using in vitro gastrointestinal digestion models.

RESULTS

Use of 50% (v/v) ethanol yielded rambutan extract with good chemical properties. The production of hydrogel beads using a ratio of 1:3 with calcium lactate provided the highest production yield of 122.94%. The hydrogel beads developed using the ratio of 1:3 with a combination of calcium lactate and calcium chloride showed high recovery of phenolic compounds and antioxidant activity after simulated intestinal digestion, which were greater compared to unencapsulated extract.

CONCLUSION

The findings demonstrate that the ratio of wall material to rambutan extract and the calcium source influence the physical properties, chemical properties and in vitro gastrointestinal digestion stability of alginate beads. The obtained hydrogel beads may have potential for application in the food or pharmaceutical industries. © 2024 Society of Chemical Industry.

Impact of In Vitro Digestion on the Digestibility, Amino Acid Release, and Antioxidant Activity of Amaranth (Amaranthus cruentus L.) and Cañihua (Chenopodium pallidicaule Aellen) Proteins in Caco-2 and HepG2 Cells

This study evaluated the impact of in vitro gastrointestinal digestion on the digestibility, amino acid release, and antioxidant activity of proteins from amaranth (Amarantus cruentus L.) and cañihua (Chenopodium pallidicaule Aellen). Antioxidant activity was assessed using ORAC, ABTS, DPPH, and cellular antioxidant activity (CAA) assays in human intestinal Caco-2 and hepatic Hep-G2 cell lines. The results showed that amaranth had higher protein digestibility (79.19%) than cañihua (71.22%). In addition, intestinal digestion promoted the release of essential amino acids, such as leucine, lysine, and phenylalanine, in both protein concentrates. Concentrations of amaranth and cañihua proteins, ranging from 0.125 to 1.0 mg mL-1, were non-cytotoxic in both cell lines. At a concentration of 0.750 mg mL-1, simulated gastrointestinal digestion enhanced cellular antioxidant activity. Intestinal digest fractions containing peptides >5 kDa were the principal contributors to CAA in both cell lines. Notably, cañihua proteins exhibited high CAA, reaching values of 85.55% and 82.57% in Caco-2 and HepG2 cells, respectively, compared to amaranth proteins, which reached 84.68% in Caco-2 and 81.06% in HepG2 cells. In conclusion, both amaranth and cañihua proteins, after simulated gastrointestinal digestion, showcased high digestibility and released peptides and amino acids with potent antioxidant properties, underscoring their potential health benefits.

In Vitro Antioxidant Activity, Bioaccessibility, and Thermal Stability of Encapsulated Strawberry Fruit (Fragaria × ananassa) Polyphenols

Bioactive compounds in red fruits, such as strawberries, are vulnerable to digestion, and encapsulation has become an alternative for their protection. This study aims at encapsulating strawberry juice (SJ) by freeze-drying with pea protein and okra mucilage (SJPO), pea protein and psyllium mucilage (SJPP), and pea protein, psyllium mucilage, and okra mucilage (SJPPO) and investigating the in vitro release. The highest encapsulation efficiency was observed in capsule SJPPO (95.38%) and the lowest efficiency in SJPO (82.45%). Scanning electron microscopy revealed an amorphous glassy structure for the structure of the strawberry microcapsules, and X-ray diffraction confirmed that observation. However, X-ray diffraction further showed that SJPPO was crystalline, indicating a tighter crosslinking density than the other microcapsules. Fourier transform infrared spectroscopy showed peaks at 3390 and 1650 cm-1, confirming the presence of polyphenols and polysaccharides in the strawberry microcapsules. Thermal stability was higher for SJPPO, and the observed thermal transitions were due to the bonds formed between the polymers and polyphenols. Pelargonidin 3-glucoside, cyanidin 3-glucoside, cyanidin, delphinidin, malvidin 3-glucoside, ellagic acid, chlorogenic acid, catechin, and kaempferol were identified in the strawberry microcapsules. Digestion affected the compounds' content; the bioaccessibility for SJ was 39.26% and 45.43% for TPC and TAC, respectively. However, encapsulation improved the bioaccessibility of both TPC (SJPP, 51.54%; SJPO, 48.52%; and SJPPO, 54.39%) and TAC (SJPP, 61.08%; SJPO, 55.03%; and SJPPO, 71.93%). Thus, encapsulating pea protein isolate, psyllium mucilage, and okra mucilage is an effective method to facilitate targeted release and preserve the biological activities of fruits.

Effects of six different microbial strains on polyphenol profiles, antioxidant activity, and bioaccessibility of blueberry pomace with solid-state fermentation

To explore the effect of different microbial strains on blueberry pomace with solid-state fermentation (SSF), three fungi strains and three lactic acid bacteria (LAB) strains were utilized to investigate with respect to polyphenol profiles, antioxidant capacities, and bioaccessibility. Different strains exhibited different capacities for metabolizing polyphenolic compounds in blueberry pomace. The contents of 10 phenolic acids and 6 flavonoids (except (+)-catechin) were increased in blueberry pomace fermented by Lactobacillus acidophilus (LA). A similar tendency was observed in blueberry pomace fermented by Aspergillus niger (AN) and Lactobacillus plantarum (LP), where the concentration of 8 phenolic acids and 5 flavonoids was enhanced, with the following exceptions: (+)-catechin, ferulic acid, vanillic acid, and quercitrin. Chlorogenic acid and quercetin were the maximum phenolic acids and flavonoids in blueberry pomace with SSF, upgraded at 22.96 and 20.16%, respectively. Contrary to the growth of phenolic acids and flavonoid compounds, all individual anthocyanins showed a decreased trend. Only in the blueberry pomace fermented by AN, all anthocyanidins exhibit a rising trend. After SSF, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenylpicrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) radical scavenging abilities were increased by up to 33.56, 59.89, and 87.82%, respectively. Moreover, the simulated gastrointestinal digestion system revealed that SSF improved the bioaccessibility of polyphenolic compounds. Compared with other strains, LA, LP, and AN showed better excellent capacities for metabolizing polyphenolic compounds, which led to a greater increase in antioxidant activity and bioaccessibility in fermented blueberry pomace.

Exploration of probiotic attributes in lactic acid bacteria isolated from fermented Theobroma cacao L. fruit using in vitro techniques

Probiotics are known for their health-promoting properties and are recognized as beneficial microorganisms. The current investigation delves into the isolation and comprehensive in vitro characterization of lactic acid bacteria (LAB) obtained from the Indian-origin Theobroma cacao L. Forastero variety to assess their potential as probiotic candidates. Eleven LAB isolates were obtained, and among them, five exhibited classical LAB traits. These five isolates underwent rigorous in vitro characterization to evaluate their suitability as probiotics. The assessments included resilience against acid and bile salts, which are crucial for probiotic viability. Additionally, the isolates were subjected to simulated gastric and pancreatic fluids and lysozyme exposure to assess their survival rates. Auto- aggregation, co-aggregation, hydrophobicity, and exopolysaccharide production were also examined. The inhibitory potential of α-glucosidase, an enzyme related to glucose metabolism, was measured, and antioxidant activity was evaluated using DPPH and ABTS assays. A safety assessment was conducted to confirm the non-pathogenic nature of the isolates. Among the five isolates, CR2 emerged as a standout candidate with maximal bile salt hydrolase activity, phenol resistance, and lysozyme resistance. CR2 and CYF3 exhibited notable survival rates under simulated conditions. The isolates displayed variable degrees of auto-aggregation, co-aggregation, and hydrophobicity. CR2 exhibited the highest exopolysaccharide production (0.66 mg/mL), suggesting diverse applications in the food industry. CR2 also demonstrated the highest inhibition rate against α-glucosidase (56.55%) and substantial antioxidant activity (79.62% DPPH, 83.45% ABTS). Safety assessment confirmed the non- pathogenic nature of the isolates. Molecular characterization identified CR2 as Lactococcus lactis subsp. lactis and CYF3 as Limnosilactobacillus fermentum. Both strains exhibited commendable probiotic and technological attributes, positioning them as promising candidates for functional foods and beyond. This study provides valuable insights into the in vitro characterization of LAB isolated from Indian Theobroma cacao L., highlighting their potential as probiotic candidates with advantageous traits, including survival in hostile conditions, beneficial enzymatic activities, bioactivity, and other essential attributes.

The Structural Characteristics and Bioactivity Stability of Cucumaria frondosa Intestines and Ovum Hydrolysates Obtained by Different Proteases

The study aimed to investigate the effects of alcalase, papain, flavourzyme, and neutrase on the structural characteristics and bioactivity stability of Cucumaria frondosa intestines and ovum hydrolysates (CFHs). The findings revealed that flavourzyme exhibited the highest hydrolysis rate (51.88% ± 1.87%). At pH 2.0, the solubility of hydrolysate was the lowest across all treatments, while the solubility at other pH levels was over 60%. The primary structures of hydrolysates of different proteases were similar, whereas the surface hydrophobicity of hydrolysates was influenced by the types of proteases used. The hydrolysates produced by different proteases were also analyzed for their absorption peaks and antioxidant activity. The hydrolysates of flavourzyme had β-fold absorption peaks (1637 cm^-1), while the neutrase and papain hydrolysates had N-H bending vibrations. The tertiary structure of CFHs was unfolded by different proteases, exposing the aromatic amino acids and red-shifting of the λ-peak of the hydrolysate. The alcalase hydrolysates showed better antioxidant activity in vitro and better surface hydrophobicity than the other hydrolysates. The flavourzyme hydrolysates displayed excellent antioxidant stability and pancreatic lipase inhibitory activity during gastrointestinal digestion, indicating their potential use as antioxidants in the food and pharmaceutical industries.

Simulated Gastrointestinal Digestion of Nutritive Raw Bars: Assessment of Nutrient Bioavailability

Raw bars have become popular among health-conscious consumers due to their nutrient-dense ingredients and lack of additives and preservatives. However, the effect of simulated gastrointestinal digestion on the nutrient content of these bars has yet to be extensively studied. In this study, four different raw bar recipes were subjected to simulated gastrointestinal digestion to evaluate the impact on their nutrient content. The recipes have dates and almond flour as base ingredients and specific ingredients such as Maca root powder, Ginger powder, Aronia powder, Pollen, Propolis extract, Astragalus powder, and Cacao powder. These variations were intended to provide diverse flavors and potential health benefits to cater to different preferences and needs. The in vitro digestion model was designed to mimic the conditions of the human gastrointestinal tract, including the mouth, stomach, and small intestine. The results showed that the simulated gastrointestinal digestion significantly impacted the nutrient content of the bars, with varying degrees of nutrient loss observed depending on the recipe. The highest phenolic content and antioxidant activity were observed in the salivary phase for all samples. Vitamin B content generally decreases from the salivary to the intestinal stage. After digestion, the recovery rates of total phenols, antioxidant capacity, and vitamins B1, B3, and B6 varied across the recipes. The recovery rates of vitamins B1, B3, and B6 were generally high across all recipes, indicating their stability and retention during digestion. The findings suggest that simulated GI digestion provides insights into the nutrient bioavailability of raw bars. These results can inform the formulation and optimization of raw bars to enhance nutrient absorption and nutritional value. Further research is warranted to investigate the effects of different processing techniques and ingredient combinations on nutrient bioavailability.

Food nanoemulsions: how simulated gastrointestinal digestion models, nanoemulsion, and food matrix properties affect bioaccessibility of encapsulated bioactive compounds

Food nanoemulsions are known as very effective and excellent carriers for both lipophilic and hydrophilic bioactive compounds (BCs) and have been successfully used for controlled delivery and protection of BCs during gastrointestinal digestion (GID). However, due to sensitive and fragile morphology, BCs-loaded nanoemulsions have different digestion pathways depending on their properties, food matrix properties, and applied models for testing their digestibility and BCs bioaccessibility. Thus, this review gives a critical review of the behavior of encapsulated BCs into food nanoemulsions during each phase of GID in different static and dynamic in vitro digestion models, as well as of the influence of nanoemulsion and food matrix properties on BCs bioaccessibility. In the last section, the toxicity and safety of BCs-loaded nanoemulsions evaluated on in vitro and in vivo GID models have also been discussed. Better knowledge of food nanoemulsions' behavior in different models of simulated GI conditions and within different nanoemulsion and food matrix types can help to standardize the protocol for their testing aiming for researchers to compare results and design BCs-loaded nanoemulsions with better performance and higher targeted BCs bioaccessibility.

In vitro antidiabetic and antihypercholesterolemic activities of camel milk protein hydrolysates derived upon simulated gastrointestinal digestion of milk from different camel breeds

Milk protein hydrolysates derived from 4 camel breeds (Pakistani, Saheli, Hozami, and Omani) were evaluated for in vitro inhibition of antidiabetic enzymatic markers (dipeptidyl peptidase IV and α-amylase) and antihypercholesterolemic enzymatic markers (pancreatic lipase and cholesterol esterase). Milk samples were subjected to in vitro simulated gastric (SGD) and gastrointestinal digestion (SGID) conditions. In comparison with intact milk proteins, the SGD-derived milk protein hydrolysates showed enhanced inhibition of α-amylase, dipeptidyl peptidase IV, pancreatic lipase, and cholesterol esterase as reflected by lower half-maximal inhibitory concentration values. Overall, milk protein hydrolysates derived from the milk of Hozami and Omani camel breeds displayed higher inhibition of different enzymatic markers compared with milk protein hydrolysates from Pakistani and Saheli breeds. In vitro SGD and SGID processes significantly increased the bioactive properties of milk from all camel breeds. Milk protein hydrolysates from different camel breeds showed significant variations for inhibition of antidiabetic and antihypercholesterolemic enzymatic markers, suggesting the importance of breed selection for production of bioactive peptides. However, further studies on identifying the peptides generated upon SGD and SGID of milk from different camel breeds are needed.

Fibre fermentation and pig faecal microbiota composition are affected by the interaction between sugarcane fibre and (poly)phenols in vitro

We investigated the effects of (poly)phenol-rich sugarcane extract (PRSE), sugarcane fibre (SCFiber), and the combination of them (PRSE + SCFiber) on the gut microbiota and short-chain fatty acids (SCFA) production using in vitro digestion and pig faecal fermentation. Measuring total phenolic content and antioxidant activity through the in vitro digestion stages showed that PRSE + SCFiber increased the delivery of (poly)phenols to the in vitro colonic fermentation stage compared to PRSE alone. The PRSE + SCFiber modulated the faecal microbiota profile by enhancing the relative abundances of Prevotella, Lactobacillus, and Blautia, and reducing the relative abundance of Streptococcus. PRSE + SCFiber also mitigated the inhibitory effects of PRSE on SCFA production. These results suggest that the inclusion of sugarcane fibre with PRSE could increase the availability of phenolic compounds in the colon and modulate the gut microbiota towards a more favourable profile.

The In Vitro Simulated Gastrointestinal Digestion Affects the Bioaccessibility and Bioactivity of Beta vulgaris Constituents

Beetroot (Beta vulgaris L.) is an important root vegetable crop and a valuable food source of micronutrients and bioactive constituents. In this study, the bioaccessibility of minerals, organic acids, and betacyanins in beetroot powder during simulated gastrointestinal digestion was investigated, as well as the antioxidant activity of the final fractions of each phase of the process. Mineral elements were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES), organic acids by ultra-fast liquid chromatography with photodiode array detection (UFLC-PDA), and betacyanins by liquid chromatography with diode-array detection and mass spectrometry (HPLC-DAD-ESI/MSn). The oxidative hemolysis inhibition assay was used to assess the ex vivo antioxidant activity. The bioaccessibility of minerals at the end of gastrointestinal digestion ranged from 43 to 65%, depending on the mineral element. Among these, Mg was the most bioaccessible, while Ca and Fe had the lowest bioaccessibility. For organic acids, a major release during digestion was observed for quinic acid. It was also found that betanin (the major betalain in beetroot) was highly unstable during the digestion process, probably due to its hydrophilic nature, which agreed with the significant (p < 0.05) decrease in antioxidant/antihemolytic activity. These results suggest that beetroot antioxidant compounds are unstable under gastrointestinal conditions, and could be useful for future development of novel and more stable beetroot food formulations.

Release of Bioactive Peptides from Erythrina edulis (Chachafruto) Proteins under Simulated Gastrointestinal Digestion

The estimated and concerning rise in world population over the next few years and the consequent increase in food demand will lead to a deterioration in global food security. To avoid or reduce this world crisis, informed and empowered consumers are turning to sustainable and nutrient-rich foods that substitute animal products, also reducing their associated environmental impact. Moreover, due to the demonstrated influence of diet on the risk of high incidence and mortality of noncommunicable diseases, the current established food pattern is focused on the consumption of foods that have functionality for health. Among these new foods, traditional and underutilized plants are gaining interest as alternative protein sources providing nutritional and biological properties. In this work, the potential of Erythrina edulis (chachafruto) proteins as a source of multifunctional peptides after transit through the gastrointestinal tract has been demonstrated, with antioxidant and immunostimulating effects in both biochemical assays and cell culture. While low molecular weight peptides released during the digestive process were found to be responsible for protection against oxidative stress mediated by their radical scavenging activity, high molecular weight peptides exerted immunostimulating effects by upregulation of immunoresponse-associated biomarkers. The findings of this study support the promising role of chachafruto proteins as a new antioxidant and immunostimulatory ingredient for functional foods and nutraceuticals.

Current trends and perspectives on bioaccessibility and bioavailability of food bioactive peptides: in vitro and ex vivo studies

The bioaccessibility and bioavailability of food-derived bioactive compounds are important issues when assessing their in vivo physiological health-promoting effects. Food components such as proteins and peptides are exposed to different proteases and peptidases during gastrointestinal digestion and absorption. Different in vitro approaches have therefore been developed to evaluate the bioaccessibility and stability of bioactive peptides. The static simulated gastrointestinal digestion model (SGD) was widely reported to assess the bioaccessibility of bioactive peptides. On the other hand, although the dynamic SGD model may better simulate human digestion, it has rarely been explored in bioaccessibility studies of food bioactive peptides due to its high cost and lack of standardization. For bioavailability studies, the Caco-2 cell monolayer model has been used extensively for the assessment of food bioactive peptides. In fact, very few reports using alternative methods for determining transepithelial transport of bioactive peptides have been employed. In this sense, ex vivo tissue-based models such as the Ussing chamber and the everted sac gut have been used. Current evidence supports the fact that using SGD with cell-based models for evaluating the bioaccessibility, absorption, and bioavailability of food-derived bioactive peptides, is the most commonly used approach. Nevertheless, SGD with ex vivo tissue-based models such as the everted sac, remains to be further explored because it seems to be the model that better mimics the physiological process - it is also fast and inexpensive, and several compounds may be tested simultaneously. In the present review, we discuss information available on the different in vitro approaches for the determination of bioaccessibility and bioavailability of food-derived bioactive peptides with special emphasis on ex vivo tissue-based models such as the everted sac and the Ussing chamber models. © 2022 Society of Chemical Industry.

Preparation, Characterization and In Vitro Stability of a Novel ACE-Inhibitory Peptide from Soybean Protein

A soy protein isolate was hydrolyzed with Alcalase®, Flavourzyme® and their combination, and the resulting hydrolysates (A, F and A + F) were ultrafiltered and analyzed through SDS-PAGE. Fractions with MW < 1 kDa were investigated for their ACE-inhibitory activity, and the most active one (A < 1 kDa) was purified by semi-preparative RP-HPLC, affording three further subfractions. NMR analysis and Edman degradation of the most active subfraction (A1) enabled the identification of four putative sequences (ALKPDNR, VVPD, NDRP and NDTP), which were prepared by solid-phase synthesis. The comparison of their ACE-inhibitory activities suggested that the novel peptide NDRP might be the main agent responsible for A1 fraction ACE inhibition (ACE inhibition = 87.75 ± 0.61%; IC50 = 148.28 ± 9.83 μg mL−1). NDRP acts as a non-competitive inhibitor and is stable towards gastrointestinal simulated digestion. The Multiple Reaction Monitoring (MRM) analysis confirmed the presence of NDRP in A < 1 kDa.

Manufacture of Whey Protein Hydrolysates Using Plant Enzymes: Effect of Processing Conditions and Simulated Gastrointestinal Digestion on Angiotensin-I-Converting Enzyme (ACE) Inhibitory Activity

Hydrolysis of proteins leads to the release of bioactive peptides with positive impact on human health. Peptides exhibiting antihypertensive properties (i.e., inhibition of angiotensin-I-converting enzyme) are commonly found in whey protein hydrolysates made with enzymes of animal, plant or microbial origin. However, bioactive properties can be influenced by processing conditions and gastrointestinal digestion. In this study, we evaluated the impact of three plant enzymes (papain, bromelain and ficin) in the manufacture of whey protein hydrolysates with varying level of pH, enzyme-to-substrate ratio and time of hydrolysis, based on a central composite design, to determine the degree of hydrolysis and antihypertensive properties. Hydrolysates made on laboratory scales showed great variation in the type of enzyme used, their concentrations and the pH level of hydrolysis. However, low degrees of hydrolysis in papain and bromelain treatments were associated with increased antihypertensive properties, when compared to ficin. Simulated gastrointestinal digestion performed for selected hydrolysates showed an increase in antihypertensive properties of hydrolysates made with papain and bromelain, which was probably caused by further release of peptides. Several peptides with reported antihypertensive properties were found in all treatments. These results suggest plant enzymes used in this study can be suitable candidates to develop ingredients with bioactive properties.

plantarum 75 in Different Biopolymeric Matrices after In Vitro Digestion

Biopolymeric systems that co-encapsulate probiotics and bioactive compounds ensure timely delivery in the gastrointestinal tract. Cyanidin 3-sambubioside is the dominant anthocyanin in Natal plum (Carissa macrocarpa). This study aims at the co-encapsulation of Natal plum (Carissa macrocarpa) juice inoculated with Lactiplantibacillus plantarum 75 (Ltp. plantarum 75) by freeze-drying using pea protein isolate, maltodextrin, and psyllium mucilage and evaluating their release in vitro. An encapsulation efficiency of >85% was noted in lactic acid bacteria (LAB) survival and anthocyanin content. Freeze-drying produced pinkish-red powder, rich in polyphenols and LAB (>6 Log CFU mL−1) after 14 days of storage. Natal plum juice + maltodextrin + pea protein isolate + psyllium mucilage + Ltp. plantarum 75 (NMPeaPsyB) showed the highest LAB population (6.74 Log CFU mL−1) with a survival rate of 81.9%. After digestion, NMPeaPsyB and NMPeaPsy had the highest LAB survival (>50%) at 67.5% and 67.5 ± 0.75%, respectively, and the highest bioaccessibility of cyanidin 3-sambubioside in Natal plum juice than the other co-encapsulation with other biopolymers. NMPeaPsy and NMPeaPsyB showed phenolic stability in the gastric phase and controlled release in the intestinal simulated phase. The antioxidant activities had strong correlations with cyanidin 3-sambubioside. The results confirmed that microencapsulation is important for improving stability and allowing for the development of functional foods.

Tripeptide Hyp-Asp-Gly from collagen peptides inhibited platelet activation via regulation of PI3K/Akt-MAPK/ERK1/2 signaling pathway

Platelet activation is involved in cardiovascular thrombosis. Our previous study demonstrated that oral administration of collagen peptides (CPs) inhibited platelet activation, but the mechanism of action of CPs remained to be elucidated. As a continued effort, the objective of this study was to identify the active ingredient of CPs and clarify its molecular mechanism. Simulated absorbate of CPs was prepared by simulated gastrointestinal digestion and intestinal absorption system, and then separated by C18 column. The fraction with the highest antiplatelet activity was subjected to NanoUPLC-ESI-MS/MS for peptide sequencing. Novel tripeptide Hyp-Asp-Gly (ODG) was identified. It had a broad-spectrum inhibition of platelet activation induced by collagen, thrombin, and adenosine diphosphate (ADP). ODG could survive simulated gastrointestinal digestion and be absorbed intact. Furthermore, it showed good stability in plasma. ODG had no significant effect on the PLC-PKC-Ca²⁺ pathway, but it inhibited the PI3K/Akt-MAPK/ERK1/2 signaling. At a dosage of 200 µmol/kg body weight, ODG had an in vivo anti-thrombosis activity without bleeding risk. The present study provides one of the mechanisms of action of CPs and highlights its potential use as a functional component to combat cardiovascular thrombosis. PRACTICAL APPLICATION: This study has suggested that tripeptide Hyp-Asp-Gly(ODG) derived from collagen have potent activities. This novel collagen peptide had a greatpotential to be applied to combat cardiovascular thrombosis in the foodindustry. Meanwhile, this work is expected to provide a theoretical basis forthe development of safe and effective anti-platelet and anti-thrombosis peptides.

Metabolites of Prickly Rose: Chemodiversity and Digestive-Enzyme-Inhibiting Potential of Rosa acicularis and the Main Ellagitannin Rugosin D

Prickly rose (Rosaacicularis Lindl.) is the most distributed rose species in the Northern Hemisphere, used by indigenous people for various food purposes. The lack of detailed information about the chemical composition of R. acicularis has led us to study the phytochemical composition and metabolic profile of prickly rose extracts using chromatographic techniques. Many groups of phenolic and non-phenolic compounds were quantified in the leaves, flowers, roots and fruits of R. acicularis. Phenolic compounds were the dominant phytochemicals in the aerial parts and roots of R. acicularis. A precise study by high-performance liquid chromatography with photodiode array detection and electrospray ionization triple quadrupole mass spectrometric detection showed the presence of 123 compounds, among which ellagic acid derivatives, ellagitannins, gallotannins, catechins, catechin oligomers, hydroxycinnamates and flavonoid glycosides of kaempferol, quercetin and dihydroquercetin were all identified for the first time. The most abundant phenolic compounds were ellagitannins and flavonoid glycosides, with a maximal content of 70.04 mg/g in leaves and 66.72 mg/g in flowers, respectively, indicating the great ability of R. acicularis organs to accumulate phenolic compounds. By applying a standardized static, simulated gastrointestinal digestion method, we found the inhibitory potential of the leaf extract against digestive α-amylases. A pancreatic α-amylase activity-inhibiting assay coupled with HPLC microfractionation demonstrated high inhibition of enzyme activity by ellagitannin rugosin D, which was later confirmed by a microplate reaction with mammalian α-amylases and the simulated digestion method. This study clearly demonstrates that R. acicularis leaf extract and its main component, ellagitannin rugosin D, strongly inhibit digestive α-amylase, and may be a prospective antidiabetic agent.

Red Wine High-Molecular-Weight Polyphenolic Complex: An Emerging Modulator of Human Metabolic Disease Risk and Gut Microbiota

Moderate red wine consumption has been linked to reduced chronic disease risk. Thus far, little has been known about the physicochemical properties and potential biological effects of high-molecular-weight polyphenolic complexes (HPPCs), a major fraction of red wine polyphenols. In this work, the stability and biochemical properties of HPPCs under simulated gastrointestinal conditions in vitro were studied. The results showed that HPPCs were resistant to simulated gastric digestion (SGD) and simulated intestinal digestion (SID). They exhibited significant inhibitory activity against key metabolic syndrome-associated digestive enzymes, achieving 17.1-90.9% inhibition of pancreatic α-amylase, lipase, and cholesterol esterase at 0.02-0.45 mg/mL. HPPCs were metabolized by gut microbiota (GM), leading to significantly enhanced antioxidant capacity when compared with the original, SGD, and SID samples. Furthermore, they favorably modulated GM profiles, which was accompanied by significantly increased short-chain fatty acid generation during the early colonic fermentation phase. These findings suggest that HPPCs are a promising modulator of human metabolic disease risk.

β-Glucan Interaction with Lentil (Lens culinaris) and Yellow Pea (Pisum sativum) Proteins Suppresses Their In Vitro Digestibility

In this study, β-glucan interaction with lentil and yellow pea proteins and the effect on in vitro protein digestibility were investigated. Proteins were mixed with β-glucan at mass ratios of 1:0.5, 1:1, and 1:2. The interaction between β-glucan and the proteins was demonstrated by the decrease in transmittance and surface charge and the increase in particle size of the complexes. Bright-field microscopy showed the formation of aggregates between the biopolymers, although increased molecular size was not observed by discontinuous native polyacrylamide gel electrophoresis. Fluorescence microscopy indicated that β-glucan formed aggregates with lentil proteins, while the interaction with yellow pea proteins appeared as distinct phases of protein within the β-glucan network. The in vitro protein digestibility of lentil and pea protein decreased by 27.3 and 34.5%, respectively, in the presence of a β-glucan mass ratio of 1:2. The findings confirm the possibility to modulate protein digestibility by changing the physical characteristics of a food matrix.

Protein hydrolysates from Pleurotus geesteranus obtained by simulated gastrointestinal digestion exhibit neuroprotective effects in H2 O2 -injured PC12 cells

Neurodegenerative diseases are considered to be among the diseases most threatening to human beings. Increasing evidence shows that antioxidant hydrolysates/peptides with neuroprotective effects may relieve neurodegenerative diseases. However, related research in mushrooms, one of the richest sources of antioxidant hydrolysates/peptides, is in its infancy. Therefore, the in vitro neuroprotective effects of protein hydrolysates from Pleurotus geesteranus were researched in this study. Proteins were extracted from P. geesteranus and then hydrolyzed by simulated gastrointestinal digestion. The neuroprotective effects of the protein hydrolysates were evaluated by H₂ O₂ -injured PC12 cells. The hydrolysates showed a superior antioxidative ability and had a higher abundance of hydrophobic amino acids (e.g., leucine, alanine, and phenylalanine). Neither cytotoxicity nor the increase of ROS in PC12 cells was observed under treatment with the hydrolysates. However, pre-treatment with the hydrolysates in PC12 cells, which were then injured by H₂ O₂ , markedly attenuated ROS generation and enhanced the activities and mRNA expression of the endogenous antioxidant enzymes (catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)), leading to a 26.68% increase in cell viability. The hydrolysates exhibited strong neuroprotective activity in H₂ O₂ -injured PC12 cells, possibly by reducing ROS generation and enhancing the activity of the antioxidant enzymatic system. PRACTICAL APPLICATIONS: Antioxidant hydrolysates with neuroprotection were obtained from Pleurotus geesteranus proteins by simulating gastrointestinal digestion, which exhibited an excellent pre-protective effect in oxidatively damaged PC12 cells. Further study showed that hydrolysates pre-protection may exert antioxidant activities not only as an exogenous antioxidant to scavenge ROS but also as a gene regulator to modulate the endogenous antioxidant enzymes gene expression. These results indicated that the potential of antioxidant peptides, derived from P. geesteranus through gastrointestinal digestion, could serve as a source of bioactive molecules in the prevention, relief or even treatment of neurodegenerative disorders.

Protective effect against d-gal-induced aging mice and components of polypeptides and polyphenols in defatted walnut kernel during simulated gastrointestinal digestion

Defatted walnut kernel with pellicle (WKP) is an industrial byproduct during walnut oil extraction, which is rich in protein and polyphenols. WKP was hydrolyzed by simulated gastrointestinal digestion to obtain WKP hydrolysates (WKPHs). Results showed the protein recovery and hydrolysis degree of WKPH were 82.15 and 10.36%. The total phenol contents in WKP and WKPH were 4.90 and 40.70 mg gallic acid equivalent/g, respectively. The antiaging activity of WKPH was evaluated using a d-gal-induced aging mouse model. Results showed that WKPHs could recover the activities of SOD and T-AOC and the content of MDA in tissues and serum of the aging mice. The histological morphology of liver and kidney sections and the immunohistochemistry of TNF-α, IL-1β, and IL-6 in liver were observed. WKPH could effectively protect the tissue structure of the liver and kidney and reduce the inflammatory expression of liver in aging mice. The polypeptides and polyphenols in WKPH were further analyzed. Fifty polypeptides were identified and 12 of these peptides had Leu-Arg at the C-terminal. Forty-two polyphenols were detected, and most phenolic compounds belonged to ellagitannins. This study provided a theoretical basis for the improved processing and high-value utilization of walnut byproducts. PRACTICAL APPLICATION: Defatted walnut kernel with pellicle was hydrolyzed by simulated gastrointestinal digestion to obtain its hydrolysates. The hydrolysates have good antiaging activity in vivo. Fifty polypeptides were identified and 12 of these peptides had Leu-Arg at the C-terminal. Forty-two polyphenols were detected, and most phenolic compounds belonged to ellagitannins. This study could provide a theoretical basis for high-value utilization of walnut byproducts.

Novel Zn-Binding Peptide Isolated from Soy Protein Hydrolysates: Purification, Structure, and Digestion

In this study, a novel Zn-binding peptide, Lys-Tyr-Lys-Arg-Gln-Arg-Trp (KYKRQRW), was purified and identified from soy protein isolate hydrolysates (SPIHs). The Zn-binding peptide exhibited improved Zn-binding capacity (83.21 ± 2.65%) than SPIH solutions. CD, NMR, and Fourier transform infrared spectroscopy were used to confirm the complexation between Zn and the peptide. The results showed that the Zn-binding peptide formed a folding structure with part of the β-sheet (29.3-13.4%) turning into random coils (41.7-57.6%) during complexation. It was further proved that the binding sites were located at the oxygen atoms on the carboxyl group of the Trp side chain and nitrogen atoms on the amino group of the Lys side chain. Moreover, the Zn-peptide complex exhibited increased solubility than ZnSO₄ during simulated gastrointestinal digestion. This study highlighted that the novel soy peptide possessed a strong zinc chelate rate and had a positive effect on the gastrointestinal stability of Zn which could be utilized as a functional ingredient in future.

ACE Inhibitory Activity and Molecular Docking of Gac Seed Protein Hydrolysate Purified by HILIC and RP-HPLC

Gac (Momordica cochinchinensis Spreng.) seed proteins (GSPs) hydrolysate was investigated for angiotensin I-converting enzyme (ACE) inhibitory activities. GSPs were hydrolyzed under simulated gastrointestinal digestion using a combination of enzymes, including pepsin, trypsin, and chymotrypsin. The screening of ACE inhibitory peptides from GSPs hydrolysate was performed using two sequential bioassay-guided fractionations, namely hydrophilic interaction liquid chromatography (HILIC) and reversed-phase high-performance liquid chromatography (RP-HPLC). Then, the peptides in the fraction with the highest ACE inhibitory activity were identified by LC-MS/MS. The flow-through (FT) fraction showed the most potent ACE inhibitory activity when HILIC fractionation was performed. This fraction was further separated using RP-HPLC, and the result indicated that fraction 8 (RP-F8) showed the highest ACE inhibitory activity. In the HILIC-FT/RP-F8 fraction, 14 peptides were identified using LC-MS/MS analysis coupled with de novo sequencing. These amino acid chains had not been recorded previously and their ACE inhibitory activities were analyzed in silico using the BIOPEP database. One fragment with the amino acid sequence of ALVY showed a significant ACE inhibitory activity (7.03 ± 0.09 µM). The Lineweaver-Burk plot indicated that ALVY is a competitive inhibitor. The inhibition mechanism of ALVY against ACE was further rationalized through the molecular docking simulation, which revealed that the ACE inhibitory activities of ALVY is due to interaction with the S1 (Ala354, Tyr523) and the S2 (His353, His513) pockets of ACE. Bibliographic survey allowed the identification of similarities between peptides reported as in gac fruit and other proteins. These results suggest that gac seed proteins hydrolysate can be used as a potential nutraceutical with inhibitory activity against ACE.

Role of the Encapsulation in Bioavailability of Phenolic Compounds

Plant-derived phenolic compounds have multiple positive health effects for humans attributed to their antioxidative, anti-inflammatory, and antitumor properties, etc. These effects strongly depend on their bioavailability in the organism. Bioaccessibility, and consequently bioavailability of phenolic compounds significantly depend on the structure and form in which they are introduced into the organism, e.g., through a complex food matrix or as purified isolates. Furthermore, phenolic compounds interact with other macromolecules (proteins, lipids, dietary fibers, polysaccharides) in food or during digestion, which significantly influences their bioaccessibility in the organism, but due to the complexity of the mechanisms through which phenolic compounds act in the organism this area has still not been examined sufficiently. Simulated gastrointestinal digestion is one of the commonly used in vitro test for the assessment of phenolic compounds bioaccessibility. Encapsulation is a method that can positively affect bioaccessibility and bioavailability as it ensures the coating of the active component and its targeted delivery to a specific part of the digestive tract and controlled release. This comprehensive review aims to present the role of encapsulation in bioavailability of phenolic compounds as well as recent advances in coating materials used in encapsulation processes. The review is based on 258 recent literature references.

Identification and Antimicrobial Activity of Medium-Sized and Short Peptides from Yellowfin Tuna (Thunnus albacares) Simulated Gastrointestinal Digestion

Due to the rapidly increasing resistance to conventional antibiotics, antimicrobial peptides are emerging as promising novel drug candidates. In this study, peptide fragments were obtained from yellowfin tuna muscle by simulated gastrointestinal digestion, and their antimicrobial activity towards Gram-positive and Gram-negative bacteria was investigated. In particular, the antimicrobial activity of both medium- and short-sized peptides was investigated by using two dedicated approaches. Medium-sized peptides were purified by solid phase extraction on C18, while short peptides were purified thanks to a graphitized carbon black sorbent. For medium-sized peptide characterization, a peptidomic strategy based on shotgun proteomics analysis was employed, and identification was achieved by matching protein sequence database by homology, as yellowfin tuna is a non-model organism, leading to the identification of 403 peptides. As for short peptide sequences, an untargeted suspect screening approach was carried out by means of an inclusion list presenting the exact mass to charge ratios (m/z) values for all di-, tri- and tetrapeptides. In total, 572 short sequences were identified thanks to a customized workflow dedicated to short peptide analysis implemented on Compound Discoverer software.

Novel ACE Inhibitory Peptides Derived from Simulated Gastrointestinal Digestion in Vitro of Sesame (Sesamum indicum L.) Protein and Molecular Docking Study

The aim of this study was to isolate and identify angiotensin I-converting enzyme (ACE) inhibitory peptides from sesame protein through simulated gastrointestinal digestion in vitro, and to explore the underlying mechanisms by molecular docking. The sesame protein was enzymatically hydrolyzed by pepsin, trypsin, and α-chymotrypsin. The degree of hydrolysis (DH) and peptide yield increased with the increase of digest time. Moreover, ACE inhibitory activity was enhanced after digestion. The sesame protein digestive solution (SPDS) was purified by ultrafiltration through different molecular weight cut-off (MWCO) membranes and SPDS-VII (< 3 kDa) had the strongest ACE inhibition. SPDS-VII was further purified by NGC Quest™ 10 Plus Chromatography System and finally 11 peptides were identified by Nano UHPLC-ESI-MS/MS (nano ultra-high performance liquid chromatography-electrospray ionization mass spectrometry/mass spectrometry) from peak 4. The peptide GHIITVAR from 11S globulin displayed the strongest ACE inhibitory activity (IC50 = 3.60 ± 0.10 μM). Furthermore, the docking analysis revealed that the ACE inhibition of GHIITVAR was mainly attributed to forming very strong hydrogen bonds with the active sites of ACE. These results identify sesame protein as a rich source of ACE inhibitory peptides and further indicate that GHIITVAR has the potential for development of new functional foods.

Microbial transglutaminase alters the immunogenic potential and cross-reactivity of horse and cow milk proteins

Horse milk is a valuable raw material and a very attractive alternative for scientific research to address the issue of cow milk (CM) allergy due to its protein profile. A decrease in immunoreactive properties can be achieved by thermal, enzymatic, and hydrolytic processing. Therefore, the aim of this study was to explore the possibility of reducing the immunoreactivity of horse milk proteins by microbial transglutaminase (TG) polymerization. To determine how TG linking alters immunoreactivity under simulated digestion of the examined milk, analyses were performed before, during, and after digestion. The dose-dependent (1, 10, and 100 U) effects of microbial TG on horse and cow milk were analyzed. A consecutive 3-stage digestion was simulated with salivary, gastric, and intestinal fluids. The effects of digestion were analyzed by SDS-PAGE, particle size analysis, and size-exclusion chromatography. Immunoreactivity was assessed using competitive ELISA (β-lactoglobulin and α-casein) and immunodot (sera from 7 patients aged 3 to 13 years who are allergic to CM proteins). Horse milk contained almost half of the amount of total proteins in CM. The dose 1 U/g of total milk protein changed the immunoreactivity of both cow and horse milk. With increasing TG doses, α-casein immunoreactivity increased, and β-lactoglobulin decreased. After total digestion, horse milk was characterized by 2.4-fold lower average IgE and 4.8-fold lower IgG reactivity than CM. We found that TG alters the IgE and IgG reactivity of CM after in vitro digestion. Horse milk was less reactive to IgE and IgG than was CM, with animal and patient sera. The effect of TG on immunoreactivity depends on enzyme quantity and milk protein type. The diet based on modified horse milk proteins could be an alternative for some patients with CM protein allergy; however, confirmation through clinical trials is needed.

In Vitro Antithrombotic and Hypocholesterolemic Activities of Milk Fermented with Specific Strains of Lactococcus lactis

Milk fermented with specific lactic acid bacteria (LAB) was reported to be a rich source of metabolites, such as peptides with different biological activities that may have a positive effect on cardiovascular health. Thus, in this study, the antithrombotic and hypocholesterolemic activities of fermented milk with specific strains of Lactococcus lactis were investigated before and after exposure to a simulated gastrointestinal digestion (SGD) model. The inhibition of thrombin-induced fibrin polymerization (IC₅₀ peptide concentration necessary to inhibit thrombin activity by 50%), anticoagulant activity, inhibition of micellar solubility of cholesterol and bile acid binding capacity of water soluble fractions (WSF) <3 kDa from fermented milk were evaluated. Results indicated that the WSF from fermented milk with Lc-572 showed antithrombotic (IC₅₀ = 0.049 mg/mL) and hypocholesterolemic (55% inhibition of micellar solubility of cholesterol and 27% bile acid binding capacity) activities. Meanwhile, fermented milk with Lc-571 showed mainly antithrombotic activity (IC₅₀ = 0.045 mg/mL). On the other hand, fermented milk with Lc-600 presented mainly hypocholesterolemic activity (31.4% inhibition of micellar solubility of and 70% bile acid binding capacity). Moreover, biological activities were not lost after simulated gastrointestinal digestion conditions. Thus, fermented milk with these specific L. lactis strains show potential for the development of functional foods.

In Vitro and in Vivo Studies on the Angiotensin-Converting Enzyme Inhibitory Activity Peptides Isolated from Broccoli Protein Hydrolysate

In the present study we purified and identified peptides from broccoli protein hydrolysates and evaluated their angiotensin-converting enzyme (ACE) inhibitory activity in vitro and hypotensive effect in vivo. Three ACE inhibitory peptides were isolated and identified as IPPAYTK, LVLPGELAK, and TFQGPPHGIQVER, and their inhibitory IC₅₀ values were 23.5, 184.0, and 3.4 μM, respectively. We then investigated the effect of gastrointestinal digestion on ACE inhibitory activity. We detected almost two times the ACE inhibitory activity of the peptide LVLPGELAK following simulated digestion than prior to digestion. LVLPGE and LAK, two novel peptides exhibiting high ACE inhibitory activity, were discovered following digestion and possessed IC₅₀ values of 13.5 and 48.0 μM, respectively. The hypotensive effect of the peptides was assessed after oral administration to spontaneous hypertensive rats (SHRs). We found that LVLPGE and LAK demonstrated a significant hypotensive effect in vivo. Protein from broccoli may thus constitute a potential antihypertensive peptide source.

Simulated Gastrointestinal Digestion of Cocoa: Detection of Resistant Peptides and In Silico/In Vitro Prediction of Their Ace Inhibitory Activity

In this study we investigated the oligopeptide pattern in fermented cocoa beans and derived products after simulated gastrointestinal digestion. Peptides in digested cocoa samples were identified based on the mass fragmentation and on the software analysis of vicilin and 21 KDa cocoa seed protein sequences, the most abundant cocoa proteins. Quantification was carried out by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS) using an internal standard. Sixty five peptides were identified in the digested samples, including three pyroglutamyl derivatives. The in vitro angiotensin-converting enzyme (ACE)-inhibitory activity of cocoa digests were tested, demonstrating a high inhibition activity, especially for digestates of cocoa beans. The peptides identified were screened for their potential ACE inhibitory activity through an in silico approach, and about 20 di-, three- and tetra-peptides actually present in our samples were predicted as active. Two of the potentially active peptides were chemically synthesized and then assessed for their inhibitory activity by using the ACE in vitro assay. These peptides demonstrated an ACE inhibitory activity, however, that was too weak to explain alone the high activity of cocoa digestates, suggesting a synergic effect of all cocoa peptides. As a whole, results showed that an average chocolate portion (30 g) ensures an amount of peptides after digestion that, assuming complete absorption, could reach almost a complete inhibition of ACE.

Release of multifunctional peptides from kiwicha (Amaranthus caudatus) protein under in vitro gastrointestinal digestion

BACKGROUND

The multifactorial origin of many chronic diseases provides a new framework for the development of multifunctional foods. In this study, the effect of in vitro simulated gastrointestinal digestion of kiwicha (Amaranthus caudatus) proteins on the release of multifunctional peptides was evaluated.

RESULTS

Gastric digest showed higher angiotensin I converting enzyme (ACE) inhibitory activity while 60 min gastroduodenal digest showed the highest antioxidant, dipeptidyl peptidase IV (DPP-IV), α-amylase and Caco-2 cell viability inhibitory activities. Peptides >5 kDa were more effective in inhibiting colon cancer cell viability, whereas peptides <5 kDa were mainly responsible for the antioxidant, ACE, DPP-IV and α-amylase inhibitory activities. Thirteen peptides from amaranth sequenced proteins were identified. Structure-activity relationship analysis of the identified sequences pointed to three amaranth fragments, namely FLISCLL, SVFDEELS and DFIILE, as potential peptides able to concurrently exert antioxidant capacity and ability to inhibit both ACE and α-amylase.

CONCLUSIONS

Five of thirteen peptides identified in kiwicha protein digests show high potential to exert multifunctional properties. Thus kiwicha proteins might start to gain importance as ingredients for functional foods for the prevention and/or management of chronic diseases related to oxidative stress, hypertension and/or diabetes. © 2018 Society of Chemical Industry.

Development of Nanocomplexes for Curcumin Vehiculization Using Ovalbumin and Sodium Alginate as Building Blocks: Improved Stability, Bioaccessibility, and Antioxidant Activity

Type I (Complex I) and type II nanocomplexes (Complex II) were created in this work for curcumin (Cur) delivery using ovalbumin (OVA, 1.0% w/w) and sodium alginate (ALG, 0.5% w/w) as building blocks. OVA was heated at 90 °C for 5 min at pH 7.0 and then coated with ALG at pH 4.2 to produce Complex I; OVA-ALG electrostatic complex was created at pH 4.0, which was treated at 90 °C for 5 min thereafter yielding Complex II. Complex I presented an irregular elliptical shape with a diameter of ∼250 nm, whereas Complex II adopted a defined spherical structure of a smaller size (∼200 nm). Complex II did not dissociate at the pH range of 5-7, which was different from Complex I. Cur was loaded into the nonpolar matrix of nanocomplexes through hydrogen bonding and hydrophobic interactions, and Complex II displayed a higher loading capacity than Complex I. Nanocomplexes were resistant to pepsinolysis during simulated gastrointestinal digestion, which enhanced the stability and controlled release of loaded Cur, thereby improving Cur bioaccessibility from ∼20% (free form) to ∼60%. Additionally, nanocomplexes contributed to the cellular antioxidant activity (CAA) of Cur by promoting its cellular uptake. The CAA of Cur was also better preserved in nanocomplexes especially in Complex II after digestion owing to the increased stability and bioaccessibility. Results from this work highlighted the effect of nanocomplex encapsulation on the performance of Cur and revealed the critical role of preparation method in the physicochemical attributes of nanocomplexes.

Inhibition of Lipid Peroxidation of Kiwicha (Amaranthus caudatus) Hydrolyzed Protein Using Zebrafish Larvae and Embryos

Amaranth protein concentrate (APC) was hydrolyzed under in vitro gastrointestinal conditions. APC proteins were partially degraded by pepsin at pHs 1.2, 2.0, and 3.2. During the intestinal phase (pepsin/pancreatin enzymes at pH 7.0), no polypeptide bands were observed in the gel, suggesting the susceptibility of amaranth proteins to the action of digestive enzymes. The potent in vitro inhibition of lipid peroxidation, shown by the gastric and intestinal digests, was confirmed in the zebrafish larvae, with a 72.86% reduction in oxidation of lipids in the presence of the gastric hydrolysate at pH 2.0, compared to a 95.72% reduction in the presence of the gastrointestinal digest. APC digests were capable of reducing reactive oxygen species (ROS) production in the zebrafish embryo model with a value of fluorescence of 52.5% for the gastric hydrolysate, and 48.4% for the intestinal hydrolysate.

Antioxidant and angiotensin I-converting enzyme inhibitory activities of Xuanwei ham before and after cooking and in vitro simulated gastrointestinal digestion

Xuanwei ham is especially rich in a large amount of peptides and free amino acids under the action of protein degradation. Some of these peptides can potentially exert bioactivities of interest for human health. Traditionally, Xuanwei ham should undergo Chinese household cooking treatments before eating. However, it has not been known how its bioactivity changes after cooking and gastrointestinal digestion. Herein, Xuanwei ham is analysed before and after cooking, as well as gastrointestinal digestion being simulated so as to evaluate and compare its effect on antioxidant and angiotensin I-converting enzyme (ACE) inhibitory activities. The antioxidant activity is analysed using five different methods, and results demonstrate that cooking has some negative effects on antioxidative capacity when determined using different antioxidant methods except for a significant increment in 1,1'-diphenyl-2-picrylhydrazyl radical-scavenging activity, while ACE inhibitory activity increases significantly after cooking compared with control samples. After gastrointestinal digestion of samples, there is a significant increment of the antioxidant and ACE inhibitory activities in comparison with control and cooked samples. Particularly, after gastrointestinal digestion, free thiols content and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical-cation-scavenging activity of Xuanwei ham, respectively, increase about twice and fourfold, while ACE inhibitory activity increases about twice compared to cooked samples, reaching the value of 83.73%. Therefore, through cooking the antioxidant activity and ACE inhibitory activity of Xuanwei ham are not completely lost and a part of them is still maintained, while gastrointestinal digestion produces a significant enhancement in both bioactivities, highlighting a greater potential for a beneficial physiological effect on human health after eating it.

Antioxidant Peptides from Goat Milk Fermented by Lactobacillus casei L61: Preparation, Optimization, and Stability Evaluation in Simulated Gastrointestinal Fluid

Antioxidant peptides are currently the focus of many studies, since they eliminate free radicals in the human body without harmful effects. In the present study, Lactobacillus casei L61 was used as a starter culture to ferment goat milk because of its high capacity to produce antioxidant peptides. An optimal nutrients formula (casein, casein peptone, glucose, soybean peptone, inulin, calcium lactate, and cysteine) was investigated by Plackett⁻Burman (P⁻B) and Box⁻Behnken (B⁻B) designs for response surface methodology (RSM). Antioxidant peptides were successively isolated and purified from the fermented goat milk. Furthermore, the stability of the antioxidant peptides was evaluated in a simulated gastrointestinal tract at 37 &deg;C. The results showed that calcium lactate, glucose, and casein peptone significantly affected the antioxidant activity of goat milk. The optimal additive amounts were 0.99% (w/v) calcium lactate, 0.21% (w/v) glucose, and 0.29% (w/v) casein peptone. The hydroxyl free radical scavenging rate increased significantly (p < 0.001) from 56.50 ± 0.57% to 88.01 ± 0.69%; the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate increased up to 63.48 ± 1.22% under the optimal conditions (n = 3). Our research provides a fitted mathematical model for antioxidant peptides production. Besides, these antioxidant peptides had great stability during simulated gastrointestinal digestion.

Quality and Consumer Acceptance of Berry Fruit Pomace-Fortified Specialty Mustard

Blueberry pomace (BP) and cranberry pomace (CP) are good sources of dietary fiber and phenolics. This study aimed to develop berry fruit pomace (FP)-fortified specialty mustard with elevated bioactive compounds and ascertain consumer acceptance of a new product. Wet BP and CP were ground and incorporated into Dijon-style mustard at concentrations of 15%, 20%, and 25% (w/w). Total dietary fiber (TDF), total phenolic content (TPC), and radical scavenging activity (RSA) were evaluated for samples obtained from both chemical extraction (CE) and simulated gastrointestinal digestion (SGD). Physicochemical properties and consumer acceptance were also examined. Increasing concentrations of BP or CP significantly increased TDF of mustards from both CE (AOAC methods) and SGD, with the highest values from 25% fortifications. TDF from AOAC ranged from 26.86% to 40.16% for BP and from 26.86% to 38.42% for CP, while TDF from SGD ranged from 31.02% to 42.68% for BP and 31.02% to 63.65% for CP. From CE, no significant variation of TPC was found, but RSA significantly increased with increasing concentration of BP and CP. TPC from SGD was higher than that from CE, where TPC decreased with increasing concentration of BP or CP. RSA from SGD was lower than that from CE. Sensory scores of pomace-fortified samples were significantly lower than the control; however, informed panelists scored BP-fortified mustard significantly higher on appearance and color liking than uninformed panelists. This study demonstrated that with proper marketing, the utilization of FP in condiments is a viable option for potential health benefits.

PRACTICAL APPLICATION

This research is applicable to multiple areas of the food industry. Juice manufacturers or other companies that process raw agricultural produce can use this research as another way to repurpose biowaste, and companies making specialty condiments can use this research to inform future product development. General considerations discussed regarding the use of berry fruit pomace can be applied by any company interested in pomace reuse.

Identification of New Anti-inflammatory Peptides from Zein Hydrolysate after Simulated Gastrointestinal Digestion and Transport in Caco-2 Cells

Chronic inflammation is an underlying contributor to various chronic diseases. The objectives of this study were to investigate the anti-inflammatory activity of zein hydrolysate after simulated gastrointestinal digestion and Caco-2 cell absorption and to identify novel anti-inflammatory peptides after transport across Caco-2 cells. Three zein hydrolysates were prepared and further digested using gastrointestinal proteases; their transports were studied in Caco-2 cells. Anti-inflammatory activity was studied in endothelial EA.hy926 cells. Three zein hydrolysates and their digests significantly decreased the expression of tumor necrosis factor-α (TNF-α) induced pro-inflammatory vascular cell adhesion molecule-1 (VCAM-1) by 37.3-66.0%. Eleven novel peptides with 5-9 amino acid residues were sequenced; three peptides showed strong anti-inflammatory activity by inhibiting the VCAM-1 by 54-38.9% and intercellular cell adhesion molecule-1 (ICAM-1) by 36.5-28.6% at 0.2 mM. A new approach to identify novel anti-inflammatory peptides that could survive gastrointestinal digestion and absorption was developed.

Dietary Factors Modulate Iron Uptake in Caco-2 Cells from an Iron Ingot Used as a Home Fortificant to Prevent Iron Deficiency

Iron deficiency is a major public health concern and nutritional approaches are required to reduce its prevalence. The aim of this study was to examine the iron bioavailability of a novel home fortificant, the “Lucky Iron Fish™” (LIF) (www.luckyironfish.com/shop, Guelph, Canada) and the impact of dietary factors and a food matrix on iron uptake from LIF in Caco-2 cells. LIF released a substantial quantity of iron (about 1.2 mM) at pH 2 but this iron was only slightly soluble at pH 7 and not taken up by cells. The addition of ascorbic acid (AA) maintained the solubility of iron released from LIF (LIF-iron) at pH 7 and facilitated iron uptake by the cells in a concentration-dependent manner. In vitro digestion of LIF-iron in the presence of peas increased iron uptake 10-fold. However, the addition of tannic acid to the digestion reduced the cellular iron uptake 7.5-fold. Additionally, LIF-iron induced an overproduction of reactive oxygen species (ROS), similar to ferrous sulfate, but this effect was counteracted by the addition of AA. Overall, our data illustrate the major influence of dietary factors on iron solubility and bioavailability from LIF, and demonstrate that the addition of AA enhances iron uptake and reduces ROS in the intestinal lumen.

Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells

Food fortification programs to reduce iron deficiency anemia require bioavailable forms of iron that do not cause adverse organoleptic effects. Rodent studies show that nano-sized ferric phosphate (NP-FePO₄) is as bioavailable as ferrous sulfate, but there is controversy over the mechanism of absorption. We undertook in vitro studies to examine this using a Caco-2 cell model and simulated gastrointestinal (GI) digestion. Supernatant iron concentrations increased inversely with pH, and iron uptake into Caco-2 cells was 2–3 fold higher when NP-FePO₄ was digested at pH 1 compared to pH 2. The size and distribution of NP-FePO₄ particles during GI digestion was examined using transmission electron microscopy. The d50 of the particle distribution was 413 nm. Using disc centrifugal sedimentation, a high degree of agglomeration in NP-FePO₄ following simulated GI digestion was observed, with only 20% of the particles ≤1000 nm. In Caco-2 cells, divalent metal transporter-1 (DMT1) and endocytosis inhibitors demonstrated that NP-FePO₄ was mainly absorbed via DMT1. Small particles may be absorbed by clathrin-mediated endocytosis and micropinocytosis. These findings should be considered when assessing the potential of iron nanoparticles for food fortification.

Influence of Protein-Phenolic Complex on the Antioxidant Capacity of Flaxseed (Linum usitatissimum L.) Products

The impact of the naturally present phenolic compounds and/or proteins on the antioxidant capacity of flaxseed products (phenolic fraction, protein concentrates, and hydrolysates) before and after simulated gastrointestinal digestion was studied. For that, whole and phenolic reduced products were assessed. Four glycosylated phenolic compounds (secoisolariciresinol and ferulic, p-coumaric, and caffeic acids) were identified in flaxseed products. Phenolic fraction exerts the highest antioxidant capacity that increased by alkaline hydrolysis and by simulated gastrointestinal digestion. The action of Alcalase and digestive enzymes resulted in an increase of the antioxidant capacity of whole and phenolic reduced products. Principal component analysis showed that proteinaceous samples act as antioxidant is by H⁺ transfer, while those samples containing phenolic compounds exert their effects by both electron donation and H⁺ transfer mechanisms. Protein/peptide-phenolic complexation, confirmed by fluorescence spectra, exerted a positive effect on the antioxidant capacity, mainly in protein concentrates.

Impact of Lipid Components and Emulsifiers on Plant Sterols Bioaccessibility from Milk-Based Fruit Beverages

Sterol bioaccessibility (BA) of three plant sterol (PS)-enriched milk-based fruit beverages (MFb) with different fat contents (1.1-2.4%), lipid sources (animal or vegetable), and without or with emulsifiers (whey proteins enriched with milk fat globule membrane (MFGM) or soy lecithin) was evaluated after simulated gastrointestinal digestion. The BA of total PS followed the order 31.4% (MFbM containing milk fat and whey proteins enriched with MFGM) = 28.2% (MFbO containing extra virgin olive oil and soy lecithin) > 8.7% (MFb without fat addition). Total and individual PS content in the bioaccessible fractions followed the order MFbM > MFbO > MFb. Consequently, formulation with MFGM is proposed in beverages of this kind to ensure optimum bioavailability of PS. Our results suggest that the BA of PS is influenced by the type and quantity of fat and the emulsifier type involved.

Structure, stability, and IgE binding of the peach allergen Peamaclein (Pru p 7)

Knowledge of the structural properties of allergenic proteins is a necessary prerequisite to better understand the molecular bases of their action, and also to design targeted structural/functional modifications. Peamaclein is a recently identified 7 kDa peach allergen that has been associated with severe allergic reactions in sensitive subjects. This protein represents the first component of a new allergen family, which has no 3D structure available yet. Here, we report the first experimental data on the 3D-structure of Peamaclein. Almost 75% of the backbone resonances, including two helical stretches in the N-terminal region, and four out of six cysteine pairs have been assigned by 2D-NMR using a natural protein sample. Simulated gastrointestinal digestion experiments have highlighted that Peamaclein is even more resistant to digestion than the peach major allergen Pru p 3. Only the heat-denatured protein becomes sensitive to intestinal proteases. Similar to Pru p 3, Peamaclein keeps its native 3D-structure up to 90°C, but it becomes unfolded at temperatures of 100-120°C. Heat denaturation affects the immunological properties of both peach allergens, which lose at least partially their IgE-binding epitopes. In conclusion, the data collected in this study provide a first set of information on the molecular properties of Peamaclein. Future studies could lead to the possible use of the denatured form of this protein as a vaccine, and of the inclusion of cooked peach in the diet of subjects allergic to Peamaclein.

Identification of antioxidant peptides of Jinhua ham generated in the products and through the simulated gastrointestinal digestion system

BACKGROUND

The objective of this study was to purify and identify antioxidant peptides present in the extract of Chinese dry-cured Jinhua ham. Jinhua ham extracts were separated into five fractions (A-E) by size-exclusion chromatography. Each fraction was subjected to a simulated gastrointestinal (GI) digestion system and fractions showing strong antioxidant activities were collected and subjected to liquid chromatography combined with tandem mass spectrometry (LC/MS/MS) for further purification and identification.

RESULTS

Using MS/MS analysis, 33 peptides were identified in these fractions. Several key peptides were selected for synthesis and their antioxidant activity determined. The peptide showing strongest DPPH radical scavenging activity was GKFNV, which showed 92.7% antioxidant activity at a concentration of 1 mg mL(-1); the peptide LPGGGHGDL showed the highest hydroxyl radical scavenging activity; and LPGGGT and HA showed strong inhibition activity against erythrocyte hemolysis (about 45%) before digestion. On the other hand, KEER may contribute to Fe(2+) chelating ability in fraction C after GI digestion.

CONCLUSION

Jinhua dry-cured ham seems to be a potential source of antioxidant peptides generated in the products and in GI digestion.

Effect of processing on polyamine content and bioactive peptides released after in vitro gastrointestinal digestion of infant formulas

This study examined the influence of processing on polyamines and peptide release after the digestion of a commercial infant formula designed for children during the first months of life. Polyamine oxidase activity was not suppressed during the manufacturing process, which implicates that polyamine concentrations were reduced over time and during infant formula self-life. In gel electrophoresis, in vitro gastrointestinal digestion of samples with reduced amount of enzymes and time of digestion shows an increase in protein digestibility, reflected in the increase in nonprotein nitrogen after digestion and the disappearance of β-lactoglobulin and α-lactalbumin bands in gel electrophoresis. Depending on the sample, between 22 and 87 peptides were identified after gastrointestinal digestion. A peptide from β-casein f(98-105) with the sequence VKEAMAPK and antioxidant activity appeared in all of the samples. Other peptides with antioxidant, immunomodulatory, and antimicrobial activities were frequently found, which could have an effect on infant health. The present study confirms that the infant formula manufacturing process determines the polyamine content and peptidic profile after digestion of the infant formula. Because compositional dissimilarity between human milk and infant formula in polyamines and proteins could be responsible for some of the differences in health reported between breast-fed and formula-fed children, these changes must be taken into consideration because they may have a great effect on infant nutrition and development.

In vitro assessment of the multifunctional bioactive potential of Alaska pollock skin collagen following simulated gastrointestinal digestion

BACKGROUND

Dietary mineral deficiency, hypertension and diabetes have become serious human health problems. Dietary approaches are increasingly being investigated to address these issues. Identification of food-derived biological peptides has become an important approach to control such diseases. Peptides generated from aquatic byproducts have been shown to possess biological activities.

RESULTS

Significantly higher copper-chelating activity was observed on simulated hydrolysis of intact collagen. The collagen hydrolysate generated in the gastric stage exhibited moderate angiotensin-converting enzyme (ACE)-inhibitory activity with an IC50 value of 2.92 ± 0.22 mg mL(-1), which significantly decreased to 0.49 ± 0.02 mg mL(-1) after intestinal digestion. The dipeptidyl peptidase (DPP) IV-inhibitory potency of the collagen hydrolysate generated directly following simulated gastrointestinal digestion (SGID) (IC50 2.59 ± 0.04 mg mL(-1)) was significantly lower than that of the collagen tryptic hydrolysate (CTH) (IC50 1.53 ± 0.01 mg mL(-1)). The antioxidant activities of collagen and CTH using the ferric-reducing antioxidant power (FRAP) assay were 0.87 ± 0.10 and 1.27 ± 0.03 µmol Trolox equivalent (TE) g(-1) respectively after SGID.

CONCLUSION

This study identifies collagen as a good and inexpensive substrate for the generation of biologically active peptides with potential applications as functional ingredients in the management of chronic illness and mineral deficiency problems.