In vitro modulation of glucagon-like peptide release by DPP-IV inhibitory polyphenol-polysaccharide conjugates of sprouted quinoa yoghurt

The Discovery and Characterization of a Potent DPP-IV Inhibitory Peptide from Oysters for the Treatment of Type 2 Diabetes Based on Computational and Experimental Studies

The inhibition of dipeptidyl peptidase-IV (DPP-IV) is a promising approach for regulating the blood glucose levels in patients with type 2 diabetes (T2D). Oysters, rich in functional peptides, contain peptides capable of inhibiting DPP-IV activity. This study aims to identify the hypoglycemic peptides from oysters and investigate their potential anti-T2D targets and mechanisms. This research utilized virtual screening for the peptide selection, followed by in vitro DPP-IV activity assays to validate the chosen peptide. Network pharmacology was employed to identify the potential targets, GO terms, and KEGG pathways. Molecular docking and molecular dynamics simulations were used to provide virtual confirmation. The virtual screening identified LRGFGNPPT as the most promising peptide among the screened oyster peptides. The in vitro studies confirmed its inhibitory effect on DPP-IV activity. Network pharmacology revealed that LRGFGNPPT exerts an anti-T2D effect through multiple targets and signaling pathways. The key hub targets are AKT1, ACE, and REN. Additionally, the molecular docking results showed that LRGFGNPPT exhibited a strong binding affinity with targets like AKT1, ACE, and REN, which was further confirmed by the molecular dynamics simulations showcasing a stable peptide-target interaction. This study highlights the potential of LRGFGNPPT as a natural anti-T2D peptide, providing valuable insights for potential future pharmaceutical or dietary interventions in T2D management.

Harnessing the Potential of Quinoa: Nutritional Profiling, Bioactive Components, and Implications for Health Promotion

Quinoa, a globally cultivated "golden grain" belonging to Chenopodium in the Amaranthaceae family, is recognized for being gluten-free, with a balanced amino acid profile and multiple bioactive components, including peptides, polysaccharides, polyphenols, and saponins. The bioactive compounds extracted from quinoa offer multifaceted health benefits, including antioxidative, anti-inflammatory, antimicrobial, cardiovascular disease (CVD) improvement, gut microbiota regulation, and anti-cancer effects. This review aims to intricately outline quinoa's nutritional value, functional components, and physiological benefits. Importantly, we comprehensively provide conclusions on the effects and mechanisms of these quinoa-derived bioactive components on multiple cancer types, revealing the potential of quinoa seeds as promising and effective anti-cancer agents. Furthermore, the health-promoting role of quinoa in modulating gut microbiota, maintaining gut homeostasis, and protecting intestinal integrity was specifically emphasized. Finally, we provided a forward-looking description of the opportunities and challenges for the future exploration of quinoa. However, in-depth studies of molecular targets and clinical trials are warranted to fully understand the bioavailability and therapeutic application of quinoa-derived compounds, especially in cancer treatment and gut microbiota regulation. This review sheds light on the prospect of developing dietary quinoa into functional foods or drugs to prevent and manage human diseases.

Polysaccharide-polyphenol interactions: a comprehensive review from food processing to digestion and metabolism

Most studies on the beneficial effects of polyphenols on human health have focused on polyphenols extracted using aqueous organic solvents, ignoring the fact that a portion of polyphenols form complexes with polysaccharides. Polysaccharides and polyphenols are interrelated, and their interactions affect the physicochemical property, quality, and nutritional value of foods. In this review, the distribution of bound polyphenols in major food sources is summarized. The effect of food processing on the interaction between polyphenols and cell wall polysaccharides (CWP) is discussed in detail. We also focus on the digestion, absorption, and metabolic behavior of polysaccharide-polyphenol complexes. Different food processing techniques affect the interaction between CWP and polyphenols by altering their structure, solubility, and strength of interactions. The interaction influences the free concentration and extractability of polyphenols in food and modulates their bioaccessibility in the gastrointestinal tract, leading to their major release in the colon. Metabolism of polyphenols by gut microbes significantly enhances the bioavailability of polyphenols. The metabolic pathway and product formation rate of polyphenols and the fermentation characteristics of polysaccharides are affected by the interaction. Furthermore, the interaction exhibits synergistic or antagonistic effects on the stability, solubility, antioxidant and functional activities of polyphenols. In summary, understanding the interactions between polysaccharides and polyphenols and their changes in food processing is of great significance for a comprehensive understanding of the health benefits of polyphenols and the optimization of food processing technology.

Preparation and Characterization of a Novel Longzhua mushroom Polysaccharide Hydrogel and Slow-Release Behavior of Encapsulated Rambutan Peel Polyphenols

Natural polyphenols have drawbacks such as instability and low bioavailability, which can be overcome by encapsulated slow-release systems. Natural polymer hydrogels are ideal materials for slow-release systems because of their high biocompatibility. In this study, Longzhua mushroom polysaccharide hydrogel (LMPH) was used to encapsulate rambutan peel polyphenols (RPP) and delay their release time to improve their stability and bioavailability. The mechanical properties, rheology, stability, swelling properties, water-holding capacity, RPP loading, and slow-release behavior of LMPH were investigated. The results showed that LMPH has adequate mechanical and rheological properties, high thermal stability, excellent swelling and water-holding capacity, and good self-healing behavior. Increasing the polysaccharide content not only improved the hardness (0.17-1.13 N) and water-holding capacity of LMPH (90.84-99.32%) but also enhanced the encapsulation efficiency of RPP (93.13-99.94%). The dense network structure slowed down the release of RPP. In particular, LMPH5 released only 61.58% at 48 h. Thus, a stable encapsulated slow-release system was fabricated using a simple method based on the properties of LMPH. The developed material has great potential for the sustained release and delivery of biologically active substances.

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

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

Fermented foods: Harnessing their potential to modulate the microbiota-gut-brain axis for mental health

Over the past two decades, whole food supplementation strategies have been leveraged to target mental health. In addition, there has been increasing attention on the ability of gut microbes, so called psychobiotics, to positively impact behaviour though the microbiota-gut-brain axis. Fermented foods offer themselves as a combined whole food microbiota modulating intervention. Indeed, they contain potentially beneficial microbes, microbial metabolites and other bioactives, which are being harnessed to target the microbiota-gut-brain axis for positive benefits. This review highlights the diverse nature of fermented foods in terms of the raw materials used and type of fermentation employed, and summarises their potential to shape composition of the gut microbiota, the gut to brain communication pathways including the immune system and, ultimately, modulate the microbiota-gut-brain axis. Throughout, we identify knowledge gaps and challenges faced in designing human studies for investigating the mental health-promoting potential of individual fermented foods or components thereof. Importantly, we also suggest solutions that can advance understanding of the therapeutic merit of fermented foods to modulate the microbiota-gut-brain axis.

Recent advances in physiochemical changes, nutritional value, bioactivities, and food applications of germinated quinoa: A comprehensive review

The production and consumption of functional foods has become an essential food industry trend. Due to its high nutritional content, quinoa is regarded as a super pseudocereal for the development of nutritious foods. However, the presence of antinutritional factors and quinoa's distinctive grassy flavor limit its food applications. Due to its benefits in enhancing the nutritional bioavailability and organoleptic quality of quinoa, germination has garnered significant interest. To date, there is no systematic review of quinoa germination and the health benefits of germinated quinoa. This review details the nutritional components and bioactivities of germinated quinoa, as well as the potential mechanisms for the accumulation of bioactive compounds during the germination process. Additionally, evidence supporting the health benefits of germinated quinoa, the current status of related product development, and perspectives for future research are presented. Thus, our research is likely to provide theoretical support for the use of germinated quinoa resources.

Could Naringenin Participate as a Regulator of Obesity and Satiety?

Obesity is a serious health problem worldwide, since it is associated with multiple metabolic disorders and complications such as cardiovascular disease, type 2 diabetes, fatty liver disease and overall metabolic dysfunction. Dysregulation of the hunger-satiety pathway, which includes alterations of central and peripheral signaling, explains some forms of obesity by favoring hyperphagia and weight gain. The present work comprehensively summarizes the mechanisms by which naringenin (NAR), a predominant flavanone in citrus fruits, could modulate the main pathways associated with the development of obesity and some of its comorbidities, such as oxidative stress (OS), inflammation, insulin resistance (IR) and dyslipidemia, as well as the role of NAR in modulating the secretion of enterohormones of the satiety pathway and its possible antiobesogenic effect. The results of multiple in vitro and in vivo studies have shown that NAR has various potentially modulatory biological effects against obesity by countering IR, inflammation, OS, macrophage infiltration, dyslipidemia, hepatic steatosis, and adipose deposition. Likewise, NAR is capable of modulating peptides or peripheral hormones directly associated with the hunger-satiety pathway, such as ghrelin, cholecystokinin, insulin, adiponectin and leptin. The evidence supports the use of NAR as a promising alternative to prevent overweight and obesity.

An overview of the nutritional profile, processing technologies, and health benefits of quinoa with an emphasis on impacts of processing

Consumers are becoming increasingly conscious of adopting a healthy lifestyle and demanding food with high nutritional values. Quinoa (Chenopodium quinoa Willd.) has attracted considerable attention and is consumed worldwide in the form of a variety of whole and processed products owing to its excellent nutritional features, including richness in micronutrients and bioactive phytochemicals, well-balanced amino acids composition, and gluten-free properties. Recent studies have indicated that the diverse utilization and final product quality of this pseudo-grain are closely related to the processing technologies used, which can result in variations in nutritional profiles and health benefits. This review comprehensively summarizes the nutritional properties, processing technologies, and potential health benefits of quinoa, suggesting that quinoa plays a promising role in enhancing the nutrition of processed food. In particular, the effects of different processing technologies on the nutritional profile and health benefits of quinoa are highlighted, which can provide a foundation for the updating and upgrading of the quinoa processing industry. It further discusses the present quinoa-based food products containing quinoa as partial or whole substitute for traditional grains.

Opportunities and challenges of polyphenols and polysaccharides for type 1 diabetes intervention

Type 1 diabetes (T1D) is an autoimmune disorder characterized by the destruction of insulin-producing pancreatic β cell. It contributes to high mortality, frequent diabetic complications, poor quality of life in patients and also puts a significant economic burden on health care systems. Therefore, the development of new therapeutic strategies is urgently needed. Recently, certain dietary compounds with potential applications in food industry, particularly polyphenols and polysaccharides, have gained increasing attention with their prominent anti-diabetic effects on T1D by modulating β cell function, the gut microbiota and/or the immune system. In this review, we critically discuss the recent findings of several dietary polyphenols and polysaccharides with the potential to protect against T1D and the underlying anti-diabetic mechanisms. More importantly, we highlight the current trends, major issues, and future directions of industrial production of polyphenols- and polysaccharides-based functional foods for preventing or delaying T1D.

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

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

Quinoa Reduces High-Fat Diet-Induced Obesity in Mice via Potential Microbiota-Gut-Brain-Liver Interaction Mechanisms

The gut microbiota is important in the occurrence and development of obesity. It can not only via its metabolites, but also through microbiota-gut-brain-liver interactions, directly or indirectly, influence obesity. Quinoa, known as one kind of pseudocereals and weight loss food supplements, has been high-profile for its high nutritional value and broad applications. In this context, we produced high-fat diet-induced (HFD) obese mouse models and assessed the efficacy of quinoa with saponin and quinoa without saponin on obesity. We explored the potential therapeutic mechanisms of quinoa using methods such as 16S rRNA, Western blotting, Immunohistochemical (IHC). Our results indicated that quinoa can improve the obese symptoms significantly on HFD mice, as well as aberrant glucose and lipid metabolism. Further analyses suggest that quinoa can regulate microbiota in the colon and have predominantly regulation on Bacteroidetes, Actinobacteria and Desulfovibrio, meanwhile can decrease the F/B ratio and the abundance of Blautia. Contemporaneously, quinoa can upregulate the expression of TGR5 in the colon and brain, as well as GLP-1 in the colon, liver and brain. while downregulate the expression of TLR4 in the colon and liver, as well as markers of ER stress and oxidative stress in livers and serums. Beyond this, tight junctional proteins in colons and brains are also increased in response to quinoa. Therefore, quinoa can effectively reduce obesity and may possibly exert through microbiota-gut-brain-liver interaction mechanisms. IMPORTANCE Gut microbiota has been investigated extensively, as a driver of obesity as well as a therapeutic target. Studies of its mechanisms are predominantly microbiota-gut-brain axis or microbiota-gut-liver axis. Recent studies have shown that there is an important correlation between the gut-brain-liver axis and the energy balance of the body. Our research focus on microbiota-gut-brain-liver axis, as well as influences of quinoa in intestinal microbiota. We extend this study to the interaction between microbiota and brains, and the result shows obvious differences in the composition of the microbiome between the HFD group and others. These observations infer that besides the neurotransmitter and related receptors, microbiota itself may be a mediator for regulating bidirectional communication, along the gut-brain-liver axis. Taken together, these results also provide strong evidence for widening the domain of applicability of quinoa.

Sub-chronic consumption of a phenolic-rich avocado paste extract induces GLP-1-, leptin-, and adiponectin-mediated satiety in Wistar rats

Avocado paste (AP) is a phenolic-rich byproduct of avocado oil extraction. The effects of sub-chronic consumption of diets supplemented with an AP phenolic extract (PE) were analyzed. A standard diet (SD), high-fat diet (HFD), and these supplemented with PE (SD + PE and HFD + PE) were used. Significantly increased satiety was observed in PE-supplemented groups, according to less food consumption (-15% in SD + PE vs. SD, and -11% in HFD + PE vs. HFD), without changes in weight gain or percentage of adipose tissue. PE-supplemented groups had an increased plasma concentration ( + 16% in SD + PE vs. SD, and +26% in HFD + PE vs. HFD) and relative mRNA expression (+74% in SD + PE vs. SD, and +46% in HFD + PE vs. HFD) of GLP-1; an increase in plasma leptin and adiponectin was independent of their mRNA expression. Our results suggest that AP-derived PE exerts a satiety effect in vivo, possibly mediated by GLP-1, leptin, and adiponectin. PRACTICAL APPLICATIONS: Minimizing food waste is a top priority in most of the world, thus, researchers seek methods to reintroduce industrial fruit and vegetable byproducts into the food processing chain. The present work highlights the potential of avocado byproducts as sources of bioactive phenolic compounds, whose sub-chronic consumption (8 weeks) exerts a satiety action in vivo. Avocado farming is resource-intensive, making it of relevance to producers and processing industries to avoid discarding its byproducts as much as possible.

Slow digestion-oriented dietary strategy to sustain the secretion of GLP-1 for improved glucose homeostasis

Dysregulated glucose metabolism is associated with many chronic diseases such as obesity and type 2 diabetes mellitus (T2DM), and strategies to restore and maintain glucose homeostasis are essential to health. The incretin hormone of glucagon-like peptide-1 (GLP-1) is known to play a critical role in regulating glucose homeostasis and dietary nutrients are the primary stimuli to the release of intestinal GLP-1. However, the GLP-1 producing enteroendocrine L-cells are mainly distributed in the distal region of the gastrointestinal tract where there are almost no nutrients to stimulate the secretion of GLP-1 under normal situations. Thus, a dietary strategy to sustain the release of GLP-1 was proposed, and the slow digestion property and dipeptidyl peptidase IV (DPP-IV) inhibitory activity of food components, approaches to reduce the rate of food digestion, and mechanisms to sustain the release of GLP-1 were reviewed. A slow digestion-oriented dietary approach through encapsulation of nutrients, incorporation of viscous dietary fibers, and enzyme inhibitors of phytochemicals in a designed whole food matrix will be implemented to efficiently reduce the digestion rate of food nutrients, potentiate their distal deposition and a sustained secretion of GLP-1, which will be beneficial to improved glucose homeostasis and health.

Antidiabetic potential of dietary polyphenols: A mechanistic review

Diabetes is a metabolic disorder that has caused enormous harm to the public health worldwide. In this study, we evaluated the potential of phenolic compounds on diabetes management, addressing their mechanisms of action, in addition to discussing the digestion, absorption, metabolism, bioavailability, and toxic effects of these compounds. The intake of phenolic compounds can play a fundamental role on diabetes management, since they can reduce blood glucose levels, oxidative stress, protein glycation, inhibit the activity of dipeptidyl peptidase - IV and other key enzymes related to carbohydrate metabolism, activate various biochemical pathways to improve pancreatic β-cell functions, increase insulin secretion, and improve insulin resistance. In this way, they can be considered a potential strategy in the development of pharmaceutical approaches that aim to reduce complications resulting from the progression of this metabolic pathology.

Phenolic Bioactives From Plant-Based Foods for Glycemic Control

Plant-based foods containing phenolic bioactives have human health protective functions relevant for combating diet and lifestyle-influenced chronic diseases, including type 2 diabetes (T2D). The molecular structural features of dietary phenolic bioactives allow antioxidant functions relevant for countering chronic oxidative stress-induced metabolic breakdown commonly associated with T2D. In addition to antioxidant properties, phenolic bioactives of diverse plant foods have therapeutic functional activities such as improving insulin sensitivity, reducing hepatic glucose output, inhibiting activity of key carbohydrate digestive enzymes, and modulating absorption of glucose in the bloodstream, thereby subsequently improving post-prandial glycemic control. These therapeutic functional properties have direct implications and benefits in the dietary management of T2D. Therefore, plant-based foods that are rich in phenolic bioactives are excellent dietary sources of therapeutic targets to improve overall glycemic control by managing chronic hyperglycemia and chronic oxidative stress, which are major contributing factors to T2D pathogenesis. However, in studies with diverse array of plant-based foods, concentration and composition of phenolic bioactives and their glycemic control relevant bioactivity can vary widely between different plant species, plant parts, and among different varieties/genotypes due to the different environmental and growing conditions, post-harvest storage, and food processing steps. This has allowed advances in innovative strategies to screen and optimize whole and processed plant derived foods and their ingredients based on their phenolic bioactive linked antioxidant and anti-hyperglycemic properties for their effective integration into T2D focused dietary solutions. In this review, different pre-harvest and post-harvest strategies and factors that influence phenolic bioactive-linked antioxidant and anti-hyperglycemic properties in diverse plant derived foods and derivation of extracts with therapeutic potential are highlighted and discussed. Additionally, novel bioprocessing strategies to enhance bioavailability and bioactivity of phenolics in plant-derived foods targeting optimum glycemic control and associated T2D therapeutic benefits are also advanced.

Effects of Different Dietary Flavonoids on Dipeptidyl Peptidase-IV Activity and Expression: Insights into Structure-Activity Relationship

The inhibitory effects of 30 dietary flavonoids on dipeptidyl peptidase-IV (DPP-IV) were investigated to illustrate their quantitative structure-activity relationship (QSAR) and further explore their inhibition at the cellular level. Results of in vitro experiment show that isorhamnetin-3-O-glucoside (IC₅₀, 6.53 ± 0.280 μM) had the strongest inhibition followed by cyanidin-3-O-glucoside (IC₅₀, 8.26 ± 0.143 μM) and isorhamnetin-3-O-rutinoside (IC₅₀, 8.57 ± 0.422 μM). A 3D QSAR model [comparative molecular field analysis, q² = 0.502, optimum number of components (ONC) = 3, R² = 0.983, F = 404.378, standard error of estimation (SEE) = 0.070, and two descriptors; comparative similarity index analysis, q² = 0.580, ONC = 10, R² = 0.999, F = 1617.594, SEE = 0.022, and four descriptors] indicates that the DPP-IV inhibition of flavonoid was facilitated by crucial structural factors. Position 3 of ring C favored bulky, hydrogen bond acceptors and hydrophilic and electron-donating substituents. The presence of minor and electron-withdrawing groups at position 4' of ring B and positions 5 and 7 of ring A could improve DPP-IV inhibition. Moreover, the three flavonoids mentioned above could effectively suppress DPP-IV activity and expression in Caco-2 cells. This work may supply new insights into dietary flavonoids as DPP-IV inhibitors for controlling blood glucose.