Characterization and biological properties of peptides isolated from dried fermented cow milk products by RP-HPLC: Amino acid composition, antioxidant, antihypertensive, and antidiabetic properties

Metabolites Generated from Foods Through Lactic Fermentation and Their Benefits on the Intestinal Microbiota and Health

Metabolites generated in foods with lactic fermentation have been subject of research in recent years due to different beneficial effects attributed to them on the microbiota and health in general, including their properties as antihypertensives, antioxidants, anti-inflammatory, immunomodulatory, and antimicrobial, among others. The present review aims to systematically analyze the results of original research that evaluates effects on the microbiota and health in general, mediated by metabolites generated from the lactic fermentation of foods. The review was carried out in the PubMed database, three studies in humans, four in vivo studies in murine models, four in vitro studies, and the rest focused on the quantification of biofunctional qualities in fermented foods were analyzed. The results of the studies compiled in this systematic review reveal the potential of different food matrices and microorganisms to generate metabolites through lactic fermentation with important properties and effects on the intestinal microbiota and other health benefits. Among these benefits is the increase in short chain fatty acids to which anti-inflammatory properties are associated, as well as bioactive peptides with antihypertensive, antithrombotic, antioxidant, anti-inflammatory, and antimicrobial properties.

Assessment of hypolipidemic potential of cholesteryl esterase inhibitory peptides in different probiotic fermented milk through in vitro, in silico, and molecular docking studies

Fermented milk (FM) is well-known to confer health-promoting benefits, particularly for managing chronic metabolic diseases. However, the specific cholesterol esterase (CE) inhibitory activities of FM produced from different animal milk sources have not been extensively explored. This study for the first time investigates the CE inhibition potential of FM derived from bovine (F_BM), camel (F_CM), sheep (F_SM), and goat milk (F_GM), each fermented with five different probiotic strains and stored for 14 days under refrigeration. Further, peptides identification was performed and in silico approaches were used to dock potent peptides with CE enzyme (PDB: 1AQL) to decipher mechanism of enzyme inhibition. Comprehensive approach of this study combined CE inhibition assays, peptide identification, and in silico molecular docking with the CE enzyme (PDB: 1AQL) to elucidate mechanisms underlying enzyme inhibition. Upon fermentation improvements in CE-inhibition (lower IC50 values) were observed compared to non-fermented counterparts. Moreover, the CE-inhibition potency of the FM varies significantly among the milk types and probiotic strain (p < 0.05). Regardless of probiotic strains, CE-inhibition was more evident for F_GM followed by F_CM. Peptide sequencing and molecular docking studies revealed APSFSDIPNPIGSENSEKTTMPLW from F_BM showed potent binding to CE's active site, while peptides from F_CM, F_SM, and F_GM showed indirect CE-inhibitory mechanisms. These findings suggest potential anti-hypercholesteremic effects of bovine and non-bovine fermented milk, indicating their potential use in developing novel dairy products with hypolipidemic activities.

Advances in separation and identification of biologically important milk proteins and peptides

Milk is a rich source of biologically important proteins and peptides. In addition, milk contains a variety of extracellular vesicles (EVs), including exosomes, that carry their own proteome cargo. EVs are essential for cell-cell communication and modulation of biological processes. They act as nature carriers of bioactive proteins/peptides in targeted delivery during various physiological and pathological conditions. Identification of the proteins and protein-derived peptides in milk and EVs and recognition of their biological activities and functions had a tremendous impact on food industry, medicine research, and clinical applications. Advanced separation methods, mass spectrometry (MS)-based proteomic approaches and innovative biostatistical procedures allowed for characterization of milk protein isoforms, genetic/splice variants, posttranslational modifications and their key roles, and contributed to novel discoveries. This review article discusses recently published developments in separation and identification of bioactive proteins/peptides from milk and milk EVs, including MS-based proteomic approaches.

Functional and Bioactive Properties of Wheat Protein Fractions: Impact of Digestive Enzymes on Antioxidant, α-Amylase, and Angiotensin-Converting Enzyme Inhibition Potential

This research aimed to determine the biofunctional properties of wheat flour (WF) protein fractions and modifications to the antioxidant, anti-α-amylase and anti-angiotensin-I converting enzyme (ACE) activities induced by the action of digestive endopeptidases in vitro. A molecular characterization of the most abundant protein fractions, i.e., albumins, glutelins-1, glutelins-2 and prolamins, showed that low- and high-MW polypeptides rich in cysteine, glutamic acid and leucine were present in albumins and glutelins, whereas low-MW subunits with a high proportion of polar amino acids prevailed in prolamins. Prolamins exhibited the second-highest water holding capacity (54%) after WF (84%), while albumins provided superior foam stability (76%). Prolamins, glutenins-1 and globulins demonstrated the highest antioxidant activity (up to 95%, 68% and 59%, respectively) both before and after hydrolysis with pepsin (P-H) or trypsin-chymotrypsin (TC-H). Prolamins, globulins and WF strongly inhibited α-amylase (>90%) before and after TC-H, and before P-H (55-71%). Moreover, P-H significantly increased α-amylase inhibition by albumins from 53 to 74%. The fractions with strong ACE inhibitory activity (70-89%) included prolamins and globulins after TC-H or P-H, as well as globulins before TC-H and WF before P-H. This novel evidence indicates that WF protein fractions and their peptide-enriched P and TC hydrolysates are excellent sources of multifunctional bioactives with antioxidant, antihyperglycemic and antihypertensive potential.

Food Peptides for the Nutricosmetic Industry

In recent years, numerous reports have described bioactive peptides (biopeptides)/hydrolysates produced from various food sources. Biopeptides are considered interesting for industrial application since they show numerous functional properties (e.g., anti-aging, antioxidant, anti-inflammatory, and antimicrobial properties) and technological properties (e.g., solubility, emulsifying, and foaming). Moreover, they have fewer side effects than synthetic drugs. Nevertheless, some challenges must be overcome before their administration via the oral route. The gastric, pancreatic, and small intestinal enzymes and acidic stomach conditions can affect their bioavailability and the levels that can reach the site of action. Some delivery systems have been studied to avoid these problems (e.g., microemulsions, liposomes, solid lipid particles). This paper summarizes the results of studies conducted on biopeptides isolated from plants, marine organisms, animals, and biowaste by-products, discusses their potential application in the nutricosmetic industry, and considers potential delivery systems that could maintain their bioactivity. Our results show that food peptides are environmentally sustainable products that can be used as antioxidant, antimicrobial, anti-aging, and anti-inflammatory agents in nutricosmetic formulations. Biopeptide production from biowaste requires expertise in analytical procedures and good manufacturing practice. It is hoped that new analytical procedures can be developed to simplify large-scale production and that the authorities adopt and regulate use of appropriate testing standards to guarantee the population's safety.

Ameliorative Effects of Camel Milk and Its Exosomes on Diabetic Nephropathy in Rats

Contradictory results were obtained regarding the effects of extracellular vesicles such as exosomes (EXOs) on diabetes and diabetic nephropathy (DN). Some studies showed that EXOs, including milk EXOs, were involved in the pathogenesis of DN, whereas other studies revealed ameliorative effects. Compared to other animals, camel milk had unique components that lower blood glucose levels. However, little is known regarding the effect of camel milk and its EXOs on DN. Thus, the present study was conducted to evaluate this effect on a rat model of DN induced by streptozotocin. Treatment with camel milk and/or its EXOs ameliorated DN as evidenced by (1) reduced levels of kidney function parameters (urea, creatinine, retinol-binding protein (RBP), and urinary proteins), (2) restored redox balance (decreased lipid peroxide malondialdehyde (MDA) and increased the activity of antioxidants enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)), (3) downregulated expression of DN-related genes (transforming growth factor-beta 1 (TGFβ1), intercellular adhesion molecules 1 (ICAM1), and transformation specific 1 (ETS1), integrin subunit beta 2 (ITGβ2), tissue inhibitors of matrix metalloproteinase 2 (TIMP2), and kidney injury molecule-1 (KIM1)), and (4) decreased renal damage histological score. These results concluded that the treatment with camel milk and/or its EXOs could ameliorate DN with a better effect for the combined therapy.

The current research status and strategies employed to modify food-derived bioactive peptides

The ability of bioactive peptides to exert biological functions has mainly contributed to their exploitation. The exploitation and utilization of these peptides have grown tremendously over the past two decades. Food-derived peptides from sources such as plant, animal, and marine proteins and their byproducts constitute a more significant portion of the naturally-occurring peptides that have been documented. Due to their high specificity and biocompatibility, these peptides serve as a suitable alternative to pharmacological drugs for treating non-communicable diseases (such as cardiovascular diseases, obesity, and cancer). They are helpful as food preservatives, ingredients in functional foods, and dietary supplements in the food sector. Despite their unique features, the application of these peptides in the clinical and food sector is to some extent hindered by their inherent drawbacks such as toxicity, bitterness, instability, and susceptibility to enzymatic degradation in the gastrointestinal tract. Several strategies have been employed to eliminate or reduce the disadvantages of peptides, thus enhancing the peptide bioactivity and broadening the opportunities for their applications. This review article focuses on the current research status of various bioactive peptides and the strategies that have been implemented to overcome their disadvantages. It will also highlight future perspectives regarding the possible improvements to be made for the development of bioactive peptides with practical uses and their commercialization.

Determination of Free Amino Acids in Milk, Colostrum and Plasma of Swine via Liquid Chromatography with Fluorescence and UV Detection

Amino acids are ubiquitous components of mammalian milk and greatly contribute to its nutritional value. The compositional analysis of free amino acids is poorly reported in the literature even though their determination in the biological fluids of livestock animals is necessary to establish possible nutritional interventions. In the present study, the free amino acid profiles in mature swine milk, colostrum and plasma were assessed using a targeted metabolomics approach. In particular, 20 amino acids were identified and quantified via two alternative and complementary reversed-phase HPLC methods, involving two stationary phases based on core-shell technology, i.e., Kinetex C18 and Kinetex F5, and two detection systems, i.e., a diode array detector (DAD) and a fluorescence detector (FLD). The sample preparation involved a de-proteinization step, followed by pre-chromatographic derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl). The two optimized methods were validated for specificity, linearity, sensitivity, matrix effect, accuracy and precision and the analytical performances were compared. The analytical methods proved to be suitable for free amino acid profiling in different matrices with high sensitivity and specificity. The correlations among amino acid levels in different biological fluids can be useful for the evaluation of physio-pathological status and to monitor the effects of therapeutic or nutritional interventions in humans and animals.

Tannat Grape Skin: A Feasible Ingredient for the Formulation of Snacks with Potential for Reducing the Risk of Diabetes

In the present work the feasibility of Tannat grape skin (TGS) as a functional ingredient in the formulation of two snacks (yogurt and biscuits) was studied. The research provided novel information on the effects of the food matrix and digestion process, under simulated human oral gastrointestinal conditions, in the bioaccessibility of TGS bioactive compounds composing of the snacks with health promoting properties (antioxidant, anti-inflammatory, and antidiabetic). TGS polyphenolic profile was analyzed by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) finding mainly flavonoids, phenolic acids, and anthocyanins, which may exert antioxidant, anti-inflammatory, and carbohydrase inhibition capacities. TGS digest showed antioxidant and antidiabetic potential compared to the undigested sample (p < 0.05). Yogurt and biscuits with TGS were developed with the nutrition claims “no-added sugars” and “source of fiber” and were digested in vitro to evaluate the bioaccessibility of compounds with health promoting properties after food processing and digestion. After in vitro simulation of digestion, bioactive properties were enhanced for control and TGS snacks which may be attributed to the formation/release of compounds with health-promoting properties. Biscuits showed significant increase in ABTS antioxidant capacity and yogurt showed increased α-glucosidase inhibition capacity by the addition of TGS (p < 0.05). Polyphenols from TGS and bioactive peptides from snacks which may be released during digestion might be responsible for the observed bioactivities. Consumer’s acceptance of TGS yogurt and biscuits showed scores of 6.3 and 5.1 (scale 1−9), respectively, showing TGS yogurt had higher overall acceptance. Sensory profile assessed by check-all-that-apply + just-about-right (CATA+JAR) showed most of the attributes were evaluated as “just about right”, supporting good food quality. The developed yogurt presented adequate shelf-life parameters for 28 days. TGS yogurt with higher acceptability showed reduced ROS formation (p < 0.05) induced by tert-butyl hydroperoxide (1 mM) in CCD-18Co colon cells and RAW264.7 macrophages when pre-treated with concentrations 500−1000 and 100−500 µg/mL of the digests, respectively. Moreover, TGS yogurt digest pre-treatment reduced nitric oxide (NO) production (p < 0.05) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages, showing anti-inflammatory potential. Bioactive peptides generated during lactic fermentation and digestion process may be contributors to intracellular effects. In conclusion, yogurt and biscuits with Tannat grape skin addition were obtained with nutrition claims “no-added sugars” and “source of fiber” with the potential to modulate key biochemical events associated with diabetes pathogenesis.