Metabolic Fate and Bioavailability of Food-Derived Peptides: Are Normal Peptides Passed through the Intestinal Layer To Exert Biological Effects via Proposed Mechanisms?

Gum Arabic-Derived Hydroxyproline-Rich Peptides Stimulate Intestinal Nonheme Iron Absorption via HIF2α-Dependent Upregulation of Iron Transport Proteins

The stimulation of host iron absorption is a promising antianemia strategy adjunctive/alternative to iron intervention. Here, gum arabic (GA) containing 3.14 ± 0.56% hydroxyproline-rich protein with repetitive X-(Pro/Hyp)n motifs was found to increase iron reduction, uptake, and transport to upregulate duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), ferroportin, and hephaestin to inhibit hypoxia-inducible factor (HIF) prolyl hydroxylase (PHD) and to stabilize HIF2α in polarized Caco-2 cell monolayers in a dose-dependent manner, and this was dependent on its protein fraction, rather than the polysaccharide fraction. Three abundant GA-derived hydroxyproline-containing dipeptides of Hyp-Hyp, Pro-Hyp, and Ser-Hyp were detected by liquid chromatography-mass spectrometry in the lysates of polarized Caco-2 cell monolayers at the maximum levels of  0.167 ± 0.021, 0.134 ± 0.017, and 0.089 ± 0.015 μg/mg of protein, respectively, and showed desirable docking affinity energy values of -7.53, - 7.91, and -7.39 kcal/mol, respectively, against human PHD3. GA-derived peptides also acutely increased duodenal HIF2α stability and Dcytb, DMT1, ferroportin, and hephaestin transcription in rats (P < 0.05). Overall, GA-derived hydroxyproline-rich peptides stimulated intestinal iron absorption via PHD inhibition, HIF2α stabilization, and subsequent upregulation of iron transport proteins.

Characterization of aroma compounds in Rosa roxburghii Tratt using solvent-assisted flavor evaporation headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry and gas chromatography-olfactometry

Rosa roxburghii Tratt (RRT) has become popular owing to its high vitamin C content. Volatiles are important factors that affect the quality of RRTs and their processed products. In this study, volatile compounds were extracted using headspace-solid phase microextraction (HS-SPME) and solvent-assisted flavor evaporation (SAFE); 143 volatile compounds were identified by gas chromatography-mass spectrometry (GC-MS), and RRT from different origins were well distinguished based on principal component analysis. 45 odor-active components were identified using gas chromatography-olfactometry (GC-O). Through quantitative descriptive analysis (QDA), there were prominent "grassy" and "tea-like" attributes in RRT. Partial least-squares regression (PLSR) revealed that Longli RRT was greatly related to "tea-like" and "woody" attributes. Among the volatiles identified, alcohols and esters were considered the dominant volatile compounds of RRT, 4-methoxy-2,5-dimethyl-3(2H)-furanone was the most prominent compound. This study enriches the flavor chemistry theory of RRT and provides a scientific basis for optimizing the aroma of RRT and its processed products.

Food-derived bioactive peptides as momentous food components: Can functional peptides passed through the PI3K/Akt/mTOR pathway and NF-κB pathway to repair and protect the skeletal muscle injury?

Muscle injury is defined as an overuse injury or traumatic distraction of a muscle, which is latent in any sport event, from amateur to large events. Based on previous numbers of muscle injuries and time spent to the athletes' recovery, the use of dietary functional factors intervention strategies is essential to enhance the recovery process and health. In recent years, there has been increasing evidence that biologically active peptides played an important role in sports nutrition and muscle injure recovery. Food-derived bioactive peptides were physiologically active peptides mostly derived from proteins following hydrolysis, which could be resorbed in intact form to reduce muscle damage following exercise and induce beneficial adaptions within the connective tissue. However, the complexity of the histoarchitectural considerations for skeletal muscle injuries and the repair mechanism of damaged skeletal muscle were not well known. In the following overview, the potential mechanisms and possible limitations regarding the damaged skeletal muscle metabolism were summarized, which aimed to present an overview of the nutritional strategies and recommendations after a muscular sports injury, emphasizing the use of main bioactive peptides. In addition, this review will provide implications for the studies of dietary bioactive peptides in the future.

Potential of Food Protein-Derived Bioactive Peptides against Sarcopenia: A Comprehensive Review

Sarcopenia is an age-related progressive muscle disorder characterized by accelerated loss of muscle mass, strength, and function, which are important causes of physiological dysfunctions in the elderly. At present, the main alleviating method includes protein supplements to stimulate synthesis of muscle proteins. Food protein-derived peptides containing abundant branched-chain amino acids have a remarkable effect on the improvement of sarcopenia. Understanding the underlying molecular mechanism and clarifying the structure-activity relationship is essential for the mitigation of sarcopenia. This present review recaps the epidemiology, pathogenesis, diagnosis, and treatment of sarcopenia, which facilitates a comprehensive understanding of sarcopenia. Moreover, the latest research progress on food-derived antisarcopenic peptides is reviewed, including their antisarcopenic activity, molecular mechanism as well as structural characteristics. Food-derived bioactive peptides can indeed alleviate/mitigate sarcopenia. These antisarcopenic peptides play a pivotal role mainly by activating the PI3K/Akt/mTOR and MAPK pathways and inhibiting the ubiquitin-proteasome system and AMPK pathway, thus promoting the synthesis of muscle proteins and inhibiting their degradation. Antisarcopenic peptides alleviate sarcopenia via specific peptides, which may be absorbed into the circulation and exhibit their bioactivity in intact forms. The present review provides a theoretical reference for mitigation and prevention of sarcopenia by food protein-derived bioactive peptides.

Production of Food-Derived Bioactive Peptides with Potential Application in the Management of Diabetes and Obesity: A Review

The prevalence of diabetes mellitus and obesity is increasing worldwide. Bioactive peptides are naturally present in foods or in food-derived proteins. Recent research has shown that these bioactive peptides have an array of possible health benefits in the management of diabetes and obesity. First, this review will summarize the top-down and bottom-up production methods of the bioactive peptides from different protein sources. Second, the digestibility, bioavailability, and metabolic fate of the bioactive peptides are discussed. Last, the present review will discuss and explore the mechanisms by which these bioactive peptides help against obesity and diabetes based on in vitro and in vivo studies. Although several clinical studies have demonstrated that bioactive peptides are beneficial in alleviating diabetes and obesity, more double-blind randomized controlled trials are needed in the future. This review has provided novel insights into the potential of food-derived bioactive peptides as functional foods or nutraceuticals to manage obesity and diabetes.

Selected Soybean Varieties Regulate Hepatic LDL-Cholesterol Homeostasis Depending on Their Glycinin:β-Conglycinin Ratio

Clinical studies indicate that the consumption of soybean protein might reduce cholesterol and LDL levels preventing the development of atherosclerotic cardiovascular diseases. However, soybean variety can influence soybean protein profile and therefore affect soybean protein health-promoting properties. This study investigated the composition and effects of nineteen soybean varieties digested under simulated gastrointestinal conditions on hepatic cholesterol metabolism and LDL oxidation in vitro. Soybean varieties exhibited a differential protein hydrolysis during gastrointestinal digestion. Soybean varieties could be classified according to their composition (high/low glycinin:β-conglycinin ratio) and capacity to inhibit HMGCR (IC50 from 59 to 229 µg protein mL−1). According to multivariate analyses, five soybean varieties were selected. These soybean varieties produced different peptide profiles and differently reduced cholesterol concentration (43−55%) by inhibiting HMGCR in fatty-acid-stimulated HepG2 hepatocytes. Selected digested soybean varieties inhibited cholesterol esterification, triglyceride production, VLDL secretion, and LDL recycling by reducing ANGPTL3 and PCSK9 and synchronously increasing LDLR expression. In addition, selected soybean varieties hindered LDL oxidation, reducing the formation of lipid peroxidation early (conjugated dienes) and end products (malondialdehyde and 4-hydroxynonenal). The changes in HMGCR expression, cholesterol esterification, triglyceride accumulation, ANGPTL3 release, and malondialdehyde formation during LDL oxidation were significantly (p < 0.05) correlated with the glycinin:β-conglycinin ratio. Soybean varieties with lower glycinin:β-conglycinin exhibited a better potential in regulating cholesterol and LDL homeostasis in vitro. Consumption of soybean flour with a greater proportion of β-conglycinin may, consequently, improve the potential of the food ingredient to maintain healthy liver cholesterol homeostasis and cardiovascular function.

Collagen Peptides as a Hypoxia-Inducible Factor-2α-Stabilizing Prolyl Hydroxylase Inhibitor to Stimulate Intestinal Iron Absorption by Upregulating Iron Transport Proteins

Iron intervention is not always safe and effective to correct iron deficiency. Host iron absorption stimulation is emerging as a promising adjunctive/alternative treatment. Here, porcine collagen hydrolysate (CH) and collagen-derived dipeptide prolyl-hydroxyproline, rather than collagen amino acids, namely, glycine, proline, and hydroxyproline, were found to increase cellular iron reduction, absorption, and transportation, to upregulate duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), ferroportin (FPN), and hephaestin, and to nongenomically activate hypoxia-inducible factor-2α signaling in polarized Caco-2 cells. Prolyl-hydroxyproline showed both competitive and uncompetitive inhibition of recombinant human prolyl hydroxylase-3 activity with EC₅₀ and K_i values of 10.62 and 6.73 μM, respectively. Docking simulations revealed collagen peptides as iron chelators and/or steric hindrances for prolyl hydroxylase-3. CH and prolyl-hydroxyproline acutely increased duodenal hypoxia-inducible factor-2α stability and Dcytb, DMT1, FPN, and hephaestin transcription in rats. Overall, collagen peptides act as a hypoxia-inducible factor-2α-stabilizing prolyl hydroxylase inhibitor to stimulate intestinal iron absorption.

Stability, Bioavailability, and Structure-Activity Relationship of Casein-Derived Peptide YPVEPF with a Sleep-Enhancing Effect

YPVEPF (Tyr-Pro-Val-Glu-Pro-Phe) is an outstanding sleep-enhancing peptide derived from casein. This study aimed to evaluate the bioavailability of YPVEPF in vitro and in vivo and to explore its structure-activity relationship through a sleep test and cheminformatics. Our results showed that YPVEPF was unstable against gastrointestinal enzymes and almost totally degraded to YPVEP in vitro. However, the pharmaco-kinetics results in vivo showed that the C_max of YPVEPF was 10.38 ± 4.01 ng/mL at 5 min, and YPVEPF could be detected in the stomach, intestine, and brain at 12.89 ± 0.55, 10.26 ± 0.23, and 2.47 ± 0.55 ng/g, respectively. The main metabolites including YPVEP, YP, PVEPF, and PVEP were identified. We first explored whether the fragment YPVEP also had a strong sleep-enhancing effect, and the sleep-enhancing effects of PVEPF and PVEP (lacking a Tyr residue) significantly decreased compared with those of YPVEPF and YPVEP. Moreover, molecular docking and quantum calculations revealed that the N-terminus Tyr played a dominant role in YPVEPF and YPVEP. They had distinctive self-folding structures and varying electron-withdrawing properties of the groups at the N terminus, allowing different binding modes and electron/proton transfer.

Comprehensive Identification of Short and Medium-Sized Peptides from Pixian Broad Bean Paste Protein Hydrolysates Using UPLC-Q-TOF-MS and UHPLC-Q Exactive HF-X

Pixian broad bean paste (PBBP) is an indispensable food widely used in many East Asian countries, yet the knowledge about bioactive peptides released from parent proteins by enzymatic hydrolysis is limited. A total of 5867 low-molecular weight peptides were identified in the highly bioactive subfractions of the PBBP alcalase hydrolysates using traditional and peptidomics approaches. 19 short peptides (3-5 amino acids) were identified by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry, including 5 tripeptides, 8 tetrapeptides, and 6 pentapeptides. 5848 medium-sized peptides (6-10 amino acids) were characterized using the peptidomics approach, including 1484 hexapeptides, 1217 heptapeptides, 1634 octapeptides, 927 nonapeptides, and 586 decapeptides. The comprehensive method can be used for the investigation of bioactive peptides in complex food matrices.