The Antidiabetic Effect of Grape Pomace Polysaccharide-Polyphenol Complexes

Hemicellulose/PVA-based bioactive films for food packaging: Effect of the molecular weight of avocado pruning waste-derived hemicellulose on biocomposite properties

The rising demand for sustainable packaging and urgent need for circular strategies in the agri-food sector motivate exploring biopolymer packaging from agri-food by-products. This study presents an efficient method for utilizing avocado pruning waste (APW) by extracting hemicelluloses for polyvinyl-alcohol (PVA)-based food packaging films. Autohydrolysis and tangential-flow diafiltration produced hemicellulose fractions with varying molecular weights: >50, 50-8, 8-1, and 1 kDa. High Mw-hemicelluloses exhibited high antioxidant power (>70 %) owing to their rich ferulic and trans-cinnamic acids, while low Mw-fractions demonstrated superior antimicrobial capacity, with a Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) against L. monocytogenes of 9 mg/mL and 14 mg/mL, respectively. Hemicellulose-enriched PVA-based films displayed heightened antioxidant capacity (>40 %) and excellent UV-light blocking efficiency (>80 %) with minimal transparency loss (80 %). Low Mw-range fractions decreased water solubility (8.4 % and 7.6 % for 5 % <1 kDa and 8-1 kDa films, respectively) enhancing water absorption properties (swelling degree of 766 % for 5 % <1 kDa and 992 % for 10 % 8-1 kDa films, respectively), whereas high Mw-range fractions strengthened mechanical properties and biodegradability (67 % and 59 % improvement, respectively). The differential effects of APW-derived hemicelluloses on PVA films underscore their potential as bio-based polymer source for the packaging industry, showing improved mechanical and bioactive properties.

Ultrasound-assisted optimization extraction and biological activities analysis of flavonoids from Sanghuangporus sanghuang

The fungus Sanghuangporus sanghuang possesses notable medicinal and edible characteristics, displaying a diverse array of biological functionalities. This research endeavor seeks to investigate the procedure of extracting flavonoids from S. sanghuang, and the qualitative and quantitative analysis of flavonoids extraction from S. sanghuang using ultra-performance liquid chromatography (UPLC), and assess its antioxidant capacity and potential antiproliferative properties. The ultrasonic-assisted extraction resulted in a 2.34-fold increase compared to the hot water extraction method. Response surface methodology (RSM) was employed to enhance the extraction process of flavonoids from S. sanghuang. The results indicated that the optimal extraction rate of S. sanghuang flavonoids were achieved at 16.16 ± 0.12 %. This was attained at an ultrasound temperature of 50°C using 80 % ethanol concentration and an ultrasound extraction time of 60 min. The S. sanghuang extract was analyzed using UPLC, resulting in the identification of twenty-six distinct compounds. The flavonoids derived from S. sanghuang have demonstrated the ability to effectively scavenge DPPH, superoxide anions (O2-·), and hydroxyl free radicals (·OH), in addition to exhibiting ferric reducing power. Furthermore, it exhibited inhibitory effects on α-glucosidase. The Pearson correlation analysis revealed a statistically significant positive correlation between the antioxidant capacities, encompassing DPPH, O2-·, ·OH, ferric reducing power, and the inhibited α-glucosidase capability. It has been determined that the activity of α-glucosidase can be inhibited by S. sanghuang flavonoids, and this inhibition can be predicted using a model developed with the MATLAB program. In the current investigation, the study successfully demonstrated the inhibitory effects of S. sanghuang flavonoids on cell proliferation and migration in glioma cells. This was achieved through the analysis of CCK-8 assay and wound healing assay, with statistical significance observed (p < 0.05).

In vitro simulated digestion and fermentation characteristics of polyphenol-polysaccharide complex from Hizikia fusiforme and its effects on the human gut microbiota

This study investigated the effects of the polyphenol-polysaccharide complex (HPC) and its purified components (PC1 and PC4), obtained from Hizikia fusiforme, on the human gut microbiota during in vitro simulated digestion and fecal fermentation. Results showed a gradual increase in reducing sugar content for HPC, PC1, and PC4 during simulated digestion, accompanied by a slight decrease in molecular weight, indicating that these complexes were not completely digested during oral-gastrointestinal digestion. However, following fermentation, the molecular weights of HPC, PC1, and PC4 decreased significantly, and the molar ratios of monosaccharide compositions changed considerably compared with prefermentation values. Thus, these complexes were degraded and used by the intestinal microbiota to produce short-chain fatty acids, which decreased the pH. In addition, after fecal fermentation, beneficial bacteria such as Bacteroides, Parabacteroides, and Bifidobacterium became more abundant, whereas the amount of harmful bacteria such as Fusobacterium and Escherichia/Shigella decreased, revealing the regulation by the complex on the intestinal microbiota. In conclusion, the polyphenol-polysaccharide complex improves the composition and abundance of the human gastrointestinal microbiota, thereby supporting gut health.

Hydrolyzable tannins and pectin are glycolipid lowering ingredients in Phyllanthus emblica Linn.: Valid interaction with gut action targets

Phyllanthus emblica L., a distinctive fruit, is rich in polyphenols and polysaccharide. However, there is a lack of knowledge regarding the role of these compounds as glycolipid lowering ingredients. In this study, the glycolipid lowering ingredients and their effects have been determined by gradually comparing varieties, parts, and components, splitting components, and calculating combined index via their interactions with digestion enzymes, bile acids, cholesterol micelles and probiotics. Results indicated that the glycolipid lowering ingredients were polyphenols and polysaccharide, which located in the pulp, and not influenced by the variety. Pectin with multiple structural domains, and hydrolyzable tannins, i.e. gallic acid, ellagic acid and their derivatives interacted with multiple gut action targets could regulate glycolipid digestion, absorption and metabolism. Polysaccharide and polyphenols demonstrated a synergistic effect in lowering glycolipid by interacting with gut action targets. These findings highlight the potential for further investigation and utilization of glycolipid lowering ingredients in fruits.

Dietary supplementation with proanthocyanidins and rutin alleviates the symptoms of type 2 diabetes mice and regulates gut microbiota

Background

Obesity and high fasting blood glucose (FBG) resulting from high-fat diets (HFDs) have emerged as significant public health concerns, garnering increasing attention. Recently, gut microbiota has been linked with metabolic diseases such as type 2 diabetes (T2DM), and its mediating role in dietary supplements has been confirmed. Seeking various dietary supplements to lose body weight (BW) and decrease FBG and explaining the underlying mechanism have become the research hotspots in T2DM studies.

Methods

In this study, rutin and proanthocyanidins (PA) were selected as dietary supplements (200 mg/kg × day, oral gavage, 6 weeks) in T2DM mice induced with HFD to assess their efficacy in weight loss, FBG reduction, gut microbiota alterations, and the associated underlying mechanisms.

Results

Our findings indicate that rutin was more effective than PA in relieving inflammation and fat hypertrophy, although both significantly reduced BW and FBG within 2 weeks after the intervention. Analysis of 16S rRNA amplicons revealed substantial alterations in the gut microbial community composition of mice administered with PA and rutin compared to HFD-fed mice. Importantly, several core microbes, particularly a series of probiotics, such as Akkermansia, Lactococcus, Odoribacter, Faecalibaculum, and Roseburia were identified, which were significantly correlated with the changes in BW and FBG.

Conclusion

Overall, our study highlights that rutin and PA can reduce BW, FBG, and inflammation by modulating the gut microbiota composition, providing novel perspectives for managing and treating weight and FBG concerns in obesity and T2DM patients through dietary supplements in clinical treatment.

Natural polysaccharides: The potential biomacromolecules for treating diabetes and its complications via AGEs-RAGE-oxidative stress axis

Diabetes mellitus, a chronic metabolic disorder, poses a significantly public health challenge. Extensive research highlights that contemporary dietary patterns, characterized by excessive intake of sugar, fat, and protein, are major contributors to the onset and progression of diabetes. The central element to this process is the aberrant activation of the advanced glycation end products (AGEs) - receptor for AGEs (RAGE) - oxidative stress axis, which plays a pivotal role in disrupting normal carbohydrate metabolism. This pathway presents a critical target for developing interventions aimed at mitigating diabetes and its complications. In recent years, natural polysaccharides have emerged as promising agents in the prevention and treatment of diabetes, due to their ability to inhibit AGE formation, regulate RAGE expression, and modulate the AGEs-RAGE-oxidative stress axis. In this paper, we explore the pathogenic mechanism of this axis and review the therapeutic potential of natural polysaccharides in managing diabetes and its complications. Our goal is to provide new insights for the effective management of diabetes and its associated health challenges.

The Antidiabetic Effect of Grape Skin Extracts of Selected Indigenous Croatian White Grapevine Varieties

Grape skin is an excellent bioactive compound source with numerous beneficial health effects. This study aimed to determine and compare the antidiabetic potential of the grape skin of indigenous Croatian white grapevine varieties. The grape skin extracts (GSEs) were assessed for total polyphenols, antioxidant activity, and inhibition potential against α-amylase and α-glucosidase, enzymes responsible for carbohydrate metabolism. GSE of variety "Svetokriška belina" has the highest total phenols (TP) content (1404.87 mg of gallic acid equivalent), the highest antioxidant capacity against DPPH (544.82 mg ascorbic acid equivalent), and the highest inhibitory activity against α-amylase (99.60%). α-glucosidase was best inhibited by the variety "Kozjak" (93.53%), followed by a significantly lower inhibition by the GSE of "Svetokriška belina" (89.64%). The principal component analysis (PCA) revealed the relationship among the grape varieties by their inhibition potential, where the first PC explained 71.34% of the variation. Indigenous Croatian white grapevine varieties have great potential for developing new natural supplements to prevent and treat diabetes.

A review of in vitro antioxidant and antidiabetic polysaccharides: Extraction methods, physicochemical and structure-activity relationships

Nowadays, various plant polysaccharides have been successfully extracted which exhibited strong biological activities and might be useful for diabetes management. However, the effect of extraction methods, physicochemical and the structural-activity relationships of polysaccharides to exhibit antioxidants and antidiabetics were inadequate to explain their mechanism in action. The uses of advance extraction methods might be preferred to obtain higher antioxidants and antidiabetic activities of polysaccharides compared to conventional methods, but the determination of optimal extraction conditions might be crucial to preserve their structure and biological functions. Other than that, the physicochemical and structural properties of polysaccharides were closely related to their biological activities such as antioxidant and antidiabetic activities. Therefore, this review addressed the research gap of the influence of extraction methods, physicochemical and structural relationships of polysaccharides to biological activities, pointing out the challenges and limitations as well as future prospects to the current findings.

Star anise (Illicium verum Hook. F.) polysaccharides: Potential therapeutic management for obesity, hypertension, and diabetes

This study explores the extraction of polysaccharides from star anise (Illicium verum Hook. f.) with its anti-obesity, antihypertensive, antidiabetic, and antioxidant properties. The aim is to optimize the extraction conditions of star anise polysaccharides (SAP) utilizing propane alcohols-based deep eutectic solvents and microwave-assisted methods. The optimized conditions resulted in an extraction yield of 5.14%. The characteristics of acidic pectin-like SAP, including high viscosity (44.86 mPa s), high oil-holding capacity (14.39%), a high degree of esterification (72.53%), gel-like properties, highly amorphous, a high galacturonic acid concentration, and a highly branching size polysaccharide structure, significantly contribute to their potent inhibition of pancreatic lipase (86.67%), angiotensin-converting enzyme (73.47%), and α-glucosidase (82.33%) activities as well as to their antioxidant properties of azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, 34.94%) and ferric ion reducing antioxidant power (FRAP, 0.56 mM FeSO4). Therefore, SAP could be used as a potential therapeutic agent for obesity, hypertension, and diabetes mellitus management.

Sustainable Intervention: Grape Pomace Flour Ameliorates Fasting Glucose and Mitigates Streptozotocin-Induced Pancreatic Damage in a Type 2 Diabetes Animal Model

Background/Objectives: Type 2 Diabetes Mellitus (T2DM) is characterized by hyperglycemia, increased risk of cardiovascular diseases, and oxidative imbalances. This study aimed to investigate the impact of dietary supplementations with 'Arinto' grape pomace flour (GPF) (WGPF) and 'Touriga Nacional' GPF (RGPF) in an animal model of T2DM. Methods: T2DM was induced by a high-fat diet (HFD) for 28 days and a single dose of streptozotocin (STZ) (35 mg/kg) on the 21st day. Forty adult male Wistar rats were divided into five groups: Control (CT), T2DM, T2DM + Metformin (250 mg/kg), T2DM + 10% 'Arinto' GPF (WGPF), and T2DM + 10% 'Touriga Nacional' GPF (RGPF). On the 21st day of the experimental protocol, animals were submitted to an oral glucose tolerance test. An oral glucose tolerance test, oxidative stress parameters, biochemical analysis, and pancreas histological analyses were performed. Results: T2DM impaired glucose tolerance, elevated serum triglycerides and cholesterol, increased oxidative damage in the liver, and induced pancreatic histological abnormalities. However, supplementation with WGPF and RGPF demonstrated positive effects, mitigating glycemic and lipid disruptions, ameliorating oxidative stress, and protecting pancreatic Islets β-cells. Conclusions: Our findings highlight the protective effects of WGPF and RGPF in the adverse impacts of T2DM. Additionally, our study emphasizes the innovative use of grape pomace, a winemaking by-product, promoting sustainability by transforming waste into functional foods with significant health benefits.

From Vineyard to Vision: Efficacy of Maltodextrinated Grape Pomace Extract (MaGPE) Nutraceutical Formulation in Patients with Diabetic Retinopathy

Despite recent advances, pharmacological treatments of diabetic retinopathy (DR) do not directly address the underlying oxidative stress. This study evaluates the efficacy of a nutraceutical formulation based on maltodextrinated grape pomace extract (MaGPE), an oxidative stress inhibitor, in managing DR. A 6-month, randomized, placebo-controlled clinical trial involving 99 patients with mild to moderate non-proliferative DR was conducted. The MaGPE group showed improvement in best-corrected visual acuity (BCVA) values at T3 (p < 0.001) and T6 (p < 0.01), a reduction in CRT (at T3 and T6, both p < 0.0001) and a stabilization of vascular perfusion percentage, with slight increases at T3 and T6 (+3.0% and +2.7% at T3 and T6, respectively, compared to baseline). Additionally, the levels of reactive oxygen metabolite derivatives (dROMs) decreased from 1100.6 ± 430.1 UCARR at T0 to 974.8 ± 390.2 UCARR at T3 and further to 930.6 ± 310.3 UCARR at T6 (p < 0.05 vs. T0). Similarly, oxidized low-density lipoprotein (oxLDL) levels decreased from 953.9 ± 212.4 µEq/L at T0 to 867.0 ± 209.5 µEq/L at T3 and markedly to 735.0 ± 213.7 µEq/L at T6 (p < 0.0001 vs. T0). These findings suggest that MaGPE supplementation effectively reduces retinal swelling and oxidative stress, contributing to improved visual outcomes in DR patients.

Health-Promoting Properties and the Use of Fruit Pomace in the Food Industry-A Review

Fruit pomace, a by-product of the fruit industry, includes the skins, seeds, and pulp most commonly left behind after juice extraction. It is produced in large quantities: apple residues alone generate approximately 4 million tons of waste annually, which is a serious problem for the processing industry but also creates opportunities for various applications. Due to, among other properties, their high content of dietary fiber and polyphenolic compounds, fruit residues are used to design food with functional features, improving the nutritional value and health-promoting, technological, and sensory properties of food products. This article presents the health-promoting (antioxidant, antidiabetic, anti-inflammatory, and antibacterial) properties of fruit pomace. Moreover, the possibilities of their use in the food industry are characterized, with particular emphasis on bread, sweet snack products, and extruded snacks. Attention is paid to the impact of waste products from the fruit industry on the nutritional value and technological and sensory characteristics of these products. Fruit pomace is a valuable by-product whose use in the food industry can provide a sustainable solution for waste management and contribute to the development of functional food products with targeted health-promoting properties.

Exploring the Benefits of Nutritional and Chemical Characteristics of Touriga Nacional and Arinto Varieties (Vitis vinifera L.)

Environmental degradation leads to an unsustainable food system. In addition to this issue, the consumption of foods that improve people's health and well-being is recommended. One of the alternatives is undoubtedly the use of by-products of winemaking, namely in the form of grape pomace flour (GPF). To verify the benefits of using the Touriga Nacional and Arinto (Vitis vinifera L.) flour varieties, analytical determinations were made to identify and quantify different components. In terms of nutritional characterization, the Touriga Nacional GPF showed results that indicate better nutritional quality than the Arinto GPF. The Touriga Nacional and Arinto samples had protein contents of 10.13% and 8.38%, polyunsaturated fatty acids of 6.66% and 5.18%, soluble dietary fiber of 14.3% and 1.7%, and insoluble dietary fiber of 55.1% and 46.4%, respectively. The anthocyanins, proanthocyanidins, and flavonols presented in samples were detected by HPLC-DAD/ESI-MS. Atomic absorption spectrometry revealed elevated concentrations of certain elements in Touriga Nacional compared to Arinto, with the former showing higher levels of aluminum (130 mg/kg) and iron (146 mg/kg) against the latter's Al (120 mg/kg) and Fe (112 mg/kg) content. GPF could become a valuable ingredient due to its nutritional quality and high content of various polyphenols.

Antioxidant polysaccharide-enriched fractions obtained from olive leaves by ultrasound-assisted extraction with α-amylase inhibition, and antiproliferative activities

Polysaccharide-rich materials were extracted from the alcohol-insoluble solids of Olea europaea l. **leaves. Structural characteristics were determined by colorimetric techniques, FT-IR, GC-MS, SEC/MALS/VD/DRI, and NMR (1H,13C). The extract and its main macromolecular components were characterized to assess their ability toward antioxidant, α-amylase inhibition, and antiproliferative activities. Results revealed that the ultrasound olive leave extract comprises polysaccharides with uronic acid, galactose, arabinose, and glucose in molar percentages of 11.7%, 11.3%, 7.5%, and 4.9% respectively, constituting 41% of the total mass. In addition, polyphenols (21%) and proteins (9%) are associated with these polysaccharides. Further, the extract showed noticeable ORAC and free radical scavenging abilities, in addition to high in vitro antiproliferative activity against Caco-2 colon carcinoma cell lines. Similarly, the extract exhibited a strong, uncompetitive inhibition of α-amylase by 75% in the presence of the extract with 0.75 µg/mL of concentration. This research concludes that ultrasound extraction method can be used for the extraction of polysaccharide-polyphenol-protein complexes. These conjugates exhibit the potential for combined biological activities resulting from a synergistic effect of its compounds, making them promising ingredients for the development of functional food.

Grape Pomace-Advances in Its Bioactivity, Health Benefits, and Food Applications

From a circular economy perspective, the appropriate management and valorization of winery wastes and by-products are crucial for sustainable development. Nowadays, grape pomace (GP) has attracted increasing interest within the food field due to its valuable content, comprising nutritional and bioactive compounds (e.g., polyphenols, organic and fatty acids, vitamins, etc.). Particularly, GP polyphenols have been recognized as exhibiting technological and health-promoting effects in different food and biological systems. Hence, GP valorization is a step toward offering new functional foods and contributing to solving waste management problems in the wine industry. On this basis, the use of GP as a food additive/ingredient in the development of novel products with technological and functional advantages has recently been proposed. In this review, we summarize the current knowledge on the bioactivity and health-promoting effects of polyphenolic-rich extracts from GP samples. Advances in GP incorporation into food formulations (enhancement of physicochemical, sensory, and nutritional quality) and information supporting the intellectual property related to GP potential applications in the food industry are also discussed.

Lowering glycemic levels via gastrointestinal tract factors: the roles of dietary fiber, polyphenols, and their combination

Dietary fiber (DF) and polyphenols (DP) are typical blood sugar-lowering components, and both play distinct yet interconnected roles in exerting their blood sugar-lowering effects. We comprehensively summarized the single and combined effects of DF and DP on blood glucose homeostasis through regulating the relevant factors in the upper gastrointestinal tract (UGT) and lower gastrointestinal tract (LGT). In the UGT, DF slowed down glucose metabolism by enhancing digesta viscosity and hindering enzyme-substrate interaction. DP primarily targeted enzymes and substrates. When combined, DP enhanced the adsorption capacity of DF for glucose. DF weakened DP's inhibitory effect on enzymes. Both DF and DP disrupted glucose intestinal uptake via physical or genomic modulation, but the co-consumption of DF and DP demonstrated a lower inhibitory effect on glucose uptake than DP alone. In the LGT, DF and DP showed synergistic or antagonistic effects on gut microbiota. Remarkably, whole foods exhibited potent prebiotic effects due to their compound-rich matrix, potentially enhancing glucose homeostasis and expanding dietary options for glucose regulation research.

Novel polysaccharide and polysaccharide-peptide conjugate from Rosa rugosa Thunb. pseudofruit - Structural characterisation and nutraceutical potential

A novel bioactive polysaccharopeptide (C1) and polysaccharide (C2) with an average molecular weight of 180 kDa and 70 kDa were isolated from R. rugosa pseudofruit. The composition of the macromolecules was established using ¹H NMR, FT-IR, GC-MS, SDS-PAGE coupled with enzymatic cleavage, and proteomic analyses (LC-MS). C1 was found to contain 60.56 ± 1.82 % of sugars and 21.17 ± 0.47 % of uronic acids. Its main neutral monosaccharides were arabinose, rhamnose, galactose, glucose, fucose, and mannose. C1 was found to be a polysaccharopeptide containing pectinesterase-like protein. C2 was composed of 32.85 ± 0.97 % of sugars and 48.77 ± 1.15 % of uronic acids. Its main neutral monosaccharides were galactose, glucose, rhamnose, arabinose, and mannose. A promising nutraceutical value of the polysaccharides was revealed. Assays showed strong α-glucosidase inhibitory activity of both macromolecules and considerable antiradical potential and moderate lipoxygenase inhibitory activity of the crude polysaccharide. Moreover, antiproliferative activity of C2 was observed.

Grape Pomace as a Cardiometabolic Health-Promoting Ingredient: Activity in the Intestinal Environment

Grape pomace (GP) is a winemaking by-product particularly rich in (poly)phenols and dietary fiber, which are the main active compounds responsible for its health-promoting effects. These components and their metabolites generated at the intestinal level have been shown to play an important role in promoting health locally and systemically. This review focuses on the potential bioactivities of GP in the intestinal environment, which is the primary site of interaction for food components and their biological activities. These mechanisms include (i) regulation of nutrient digestion and absorption (GP has been shown to inhibit enzymes such as α-amylase and α-glucosidase, protease, and lipase, which can help to reduce blood glucose and lipid levels, and to modulate the expression of intestinal transporters, which can also help to regulate nutrient absorption); (ii) modulation of gut hormone levels and satiety (GP stimulates GLP-1, PYY, CCK, ghrelin, and GIP release, which can help to regulate appetite and satiety); (iii) reinforcement of gut morphology (including the crypt-villi structures, which can improve nutrient absorption and protect against intestinal damage); (iv) protection of intestinal barrier integrity (through tight junctions and paracellular transport); (v) modulation of inflammation and oxidative stress triggered by NF-kB and Nrf2 signaling pathways; and (vi) impact on gut microbiota composition and functionality (leading to increased production of SCFAs and decreased production of LPS). The overall effect of GP within the gut environment reinforces the intestinal function as the first line of defense against multiple disorders, including those impacting cardiometabolic health. Future research on GP's health-promoting properties should consider connections between the gut and other organs, including the gut-heart axis, gut-brain axis, gut-skin axis, and oral-gut axis. Further exploration of these connections, including more human studies, will solidify GP's role as a cardiometabolic health-promoting ingredient and contribute to the prevention and management of cardiovascular diseases.

Biopolymer- and Lipid-Based Carriers for the Delivery of Plant-Based Ingredients

Natural ingredients are gaining increasing attention from manufacturers following consumers’ concerns about the excessive use of synthetic ingredients. However, the use of natural extracts or molecules to achieve desirable qualities throughout the shelf life of foodstuff and, upon consumption, in the relevant biological environment is severely limited by their poor performance, especially with respect to solubility, stability against environmental conditions during product manufacturing, storage, and bioavailability upon consumption. Nanoencapsulation can be seen as an attractive approach with which to overcome these challenges. Among the different nanoencapsulation systems, lipids and biopolymer-based nanocarriers have emerged as the most effective ones because of their intrinsic low toxicity following their formulation with biocompatible and biodegradable materials. The present review aims to provide a survey of the recent advances in nanoscale carriers, formulated with biopolymers or lipids, for the encapsulation of natural compounds and plant extracts.

Polyphenol-Dietary Fiber Conjugates from Fruits and Vegetables: Nature and Biological Fate in a Food and Nutrition Perspective

In the past few years, numerous studies have investigated the correlation between polyphenol intake and the prevention of several chronic diseases. Research regarding the global biological fate and bioactivity has been directed to extractable polyphenols that can be found in aqueous-organic extracts, obtained from plant-derived foods. Nevertheless, significant amounts of non-extractable polyphenols, closely associated with the plant cell wall matrix (namely with dietary fibers), are also delivered during digestion, although they are ignored in biological, nutritional, and epidemiological studies. These conjugates have gained the spotlight because they may exert their bioactivities for much longer than extractable polyphenols. Additionally, from a technological food perspective, polyphenols combined with dietary fibers have become increasingly interesting as they could be useful for the food industry to enhance technological functionalities. Non-extractable polyphenols include low molecular weight compounds such as phenolic acids and high molecular weight polymeric compounds such as proanthocyanidins and hydrolysable tannins. Studies concerning these conjugates are scarce, and usually refer to the compositional analysis of individual components rather than to the whole fraction. In this context, the knowledge and exploitation of non-extractable polyphenol-dietary fiber conjugates will be the focus of this review, aiming to access their potential nutritional and biological effect, together with their functional properties.

Bibliometric Analysis and Visualization of Research Progress in the Diabetic Nephropathy Field from 2001 to 2021

Methods

The PubMed database was searched to identify all studies related to DN that were published from 2001 to 2021, with these studies being separated into four time-based groups. The characteristics of these studies were analyzed and extracted using BICOMB. Biclustering analyses for each of these groups were then performed using gCLUTO, with these results then being analyzed and GraphPad Prism 5 being used to construct strategy diagrams. The social network analyses (SNAs) for each group of studies were conducted using NetDraw and UCINET.

Results

In total, 18,889 DN-associated studies published from 2001 to 2021 and included in the PubMed database were incorporated into the present bibliometric analysis. Biclustering analysis and strategy diagrams revealed that active areas of research interest in the DN field include studies of the drug-based treatment, diagnosis, etiology, pathology, physiopathology, and epidemiology of DN. The specific research topics associated with these individual areas, however, have evolved over time in a dynamic manner. Strategy diagrams and SNA results revealed podocyte metabolism as an emerging research hotspot in the DN research field from 2010 to 2015, while DN-related microRNAs, signal transduction, and mesangial cell metabolism have emerged as more recent research hotspots in the interval from 2016 to 2021.

Conclusion

Through analyses of PubMed-indexed studies pertaining to DN published since 2001, the results of this bibliometric analysis offer a knowledge framework and insight into active and historical research hotspots in the DN research space, enabling investigators to readily understand the dynamic evolution of this field over the past two decades. Importantly, these analyses also enable the prediction of future DN-related research hotspots, thereby potentially guiding more focused and impactful research efforts.

Revitalizing Unfermented Cabernet Sauvignon Pomace Using an Eco-Friendly, Two-Stage Countercurrent Process: Role of pH on the Extractability of Bioactive Phenolics

As the major byproduct of the winemaking industry, grape pomace remains an untapped source of valuable bioactive phenolic compounds. This study elucidated the optimal aqueous extraction parameters for maximizing phenolic extractability, while avoiding the use of harsh conventional solvents and limiting water usage, from Cabernet Sauvignon grape pomace in which the red grape was processed for white wine. In the single-stage aqueous extraction process (AEP), the concurrent impact of pH (2.64–9.36), solids-to-liquid ratio (SLR, g pomace/mL water) (1:50–1:5), and temperature (41.6–58.4 °C) on the total phenolic content (TPC) of Cabernet Sauvignon pomace was evaluated alongside a kinetic study (15–90 min). Optimal single-stage extraction conditions (pH 9.36, 1:50 SLR, 50 °C, 75 min) guided the development of a two-stage countercurrent extraction process (pH 9.36, 1:10 SLR, 50 °C, 75 min) to further reduce water consumption without compromising overall extractability. The countercurrent process reduced fresh water usage by 80%, increased the TPC of the extracts by 18%, and improved the in vitro antioxidant activities (ABTS and ORAC) of the extracts. Untargeted metabolomics enabled the identification of a diverse pool of phenolics, especially flavonol glycosides, associated with grape pomace, while further phenolic quantitation detected improvements in the release of commonly bound phenolics such as ferulic acid, p-coumaric acid, syringic acid, and protocatechuic acid in alkaline extracts compared to the ethanolic extract. This investigation provides an efficient, eco-friendly extraction strategy suitable for applications in functional food, beverage, nutraceutical, and cosmetic industries.

Polymeric Compounds of Lingonberry Waste: Characterization of Antioxidant and Hypolipidemic Polysaccharides and Polyphenol-Polysaccharide Conjugates from Vaccinium vitis-idaea Press Cake

Lingonberry (Vaccinium vitis-idaea L.) fruits are important Ericaceous berries to include in a healthy diet of the Northern Hemisphere as a source of bioactive phenolics. The waste generated by the V. vitis-idaea processing industry is hard-skinned press cake that can be a potential source of dietary fiber and has not been studied thus far. In this study, water-soluble polysaccharides of V. vitis-idaea press cake were isolated, separated, and purified by ion-exchange and size-exclusion chromatography. The results of elemental composition, monosaccharide analysis, ultraviolet–visible and Fourier-transform infrared spectroscopy, molecular weight determination, linkage analysis, and alkaline destruction allowed us to characterize two polyphenol–polysaccharide conjugates (PPC) as neutral arabinogalactans cross-linked with monomeric and dimeric hydroxycinnamate residues with molecular weights of 108 and 157 kDa and two non-esterified galacturonans with molecular weights of 258 and 318 kDa. A combination of in vitro and in vivo assays confirmed that expressed antioxidant activity of PPC was due to phenolic-scavenged free radicals, nitrogen oxide, hydrogen peroxide, and chelate ferrous ions. Additionally, marked hypolipidemic potential of both PPC and acidic polymers bind bile acids, cholesterol, and fat, inhibit pancreatic lipase in the in vitro study, reduce body weight, serum level of cholesterol, triglycerides, low/high-density lipoprotein–cholesterol, and malondialdehyde, and increase the enzymatic activity of superoxide dismutase, glutathione peroxidase, and catalase in the livers of hamsters with a 1% cholesterol diet. Polysaccharides and PPC of V. vitis-idaea fruit press cake can be regarded as new antioxidants and hypolipidemic agents that can be potentially used to cure hyperlipidemic metabolic disorders.

Non-Commercial Grapevines Hybrids Fruits as a Novel Food of High Antioxidant Activity

Non-commercial hybrid grapevine cultivars, usually used for dessert purposes or as ornamental garden plants, may contain a wealth of bioactive substances and thus can be regarded as highly valuable food resources. Antioxidant properties and selected groups of polyphenolic components in the three fractions of fruits: peel, pulp and juice; of five hybrid grape cultivars grown in Poland—Michigan, Alwood, Minnesota, V68021 and Beta—were analyzed and characterized. The liquid chromatography coupled with tandem mass spectrometry (LC-MS-PDA-Q/TOF and UPLC-PDA), total polyphenols, flavonoids and anthocyanins, and DPPH, ABTS and FRAP were used for evaluation of antioxidant potential qualitatively and quantitatively as well as simple reductive sugars were measured. The antioxidant activity and polyphenols content depend mainly on the grape fruit fraction, while they depend to a lesser extent on the cultivar of the hybrid grapes studied. It was confirmed that grape skins are characterized by high antioxidant activity and their bioactive characteristics are similar to many hybrid grape cultivars grown in southern and Mediterranean regions of Europe. Especially grape skins of Alwood and Beta cultivars were characterized by a particularly high content of polyphenolic compounds, mainly from the flavonoid and anthocyanin group and a low content of simple sugars.

A Liposomal Formulation to Exploit the Bioactive Potential of an Extract from Graciano Grape Pomace

Antioxidant compounds with health benefits can be found in food processing residues, such as grape pomace. In this study, antioxidants were identified and quantified in an extract obtained from Graciano red grape pomace via a green process. The antioxidant activity of the extract was assessed by the DPPH and FRAP tests, and the phenolic content by the Folin–Ciocalteu test. Furthermore, nanotechnologies were employed to produce a safe and effective formulation that would exploit the antioxidant potential of the extract for skin applications. Anthocyanins, flavan-3-ols and flavanols were the main constituents of the grape pomace extract. Phospholipid vesicles, namely liposomes, were prepared and characterized. Cryo-TEM images showed that the extract-loaded liposomes were predominantly spherical/elongated, small, unilamellar vesicles. Light scattering results revealed that the liposomes were small (~100 nm), homogeneously dispersed, and stable during storage. The non-toxicity of the liposomal formulation was demonstrated in vitro in skin cells, suggesting its possible safe use. These findings indicate that an extract with antioxidant properties can be obtained from food processing residues, and a liposomal formulation can be developed to exploit its bioactive value, resulting in a promising healthy product.

Tempranillo Grape Extract in Transfersomes: A Nanoproduct with Antioxidant Activity

Polyphenols are gaining increasing interest due to their beneficial properties to human health. Grape pomace, the by-product of wine production, is a source of these bioactive compounds. An extract from Tempranillo grape pomace was obtained and characterized qualitatively and quantitatively. The major components found were anthocyanins, flavan-3-ols, and flavonols. To improve the bioavailability of these compounds, the extract was formulated in phospholipid vesicles, namely transfersomes. Spherical unilamellar vesicles around 100 nm each were obtained. The antioxidant activity of both the extract and the transfersomes was evaluated by using colorimetric assays (i.e., DPPH, FRAP, and Folin–Ciocalteu). The cells’ viability and the antioxidant activity were assessed in keratinocytes. The results showed that the extract and the transfersomes had no cytotoxic effects and exerted remarkable antioxidant activity, which was more evident in a vesicle formulation. These findings highlighted the potential of the Tempranillo grape pomace extract and the efficacy of the incorporation into phospholipid vesicles.

The Role of Nutraceutical Containing Polyphenols in Diabetes Prevention

Research in pharmacological therapy has led to the availability of many antidiabetic agents. New recommendations for precision medicine and particularly precision nutrition may greatly contribute to the control and especially to the prevention of diabetes. This scenario greatly encourages the search for novel non-pharmaceutical molecules. In line with this, the daily and long-term consumption of diets rich in phenolic compounds, together with a healthy lifestyle, may have a protective role against the development of type 2 diabetes. In the framework of the described studies, there is clear evidence that the bio accessibility, bioavailability, and the gut microbiota are indeed affected by: the way phenolic compounds are consumed (acutely or chronically; as pure compounds, extracts, or in-side a whole meal) and the amount and the type of phenolic compounds (ex-tractable or non-extractable/macromolecular antioxidants, including non-bioavailable polyphenols and plant matrix complexed structures). In this review, we report possible effects of important, commonly consumed, phenolic-based nutraceuticals in pre-clinical and clinical diabetes studies. We highlight their mechanisms of action and their potential effects in health promotion. Translation of this nutraceutical-based approach still requires more and larger clinical trials for better elucidation of the mechanism of action toward clinical applications.