Differential patterns of inhibition of the sugar transporters GLUT2, GLUT5 and GLUT7 by flavonoids

Triterpene-Based Prodrug for Self-Boosted Drug Release and Targeted Oral Squamous Cell Carcinoma Chemotherapy

Chemotherapy is one of the main treatments for oral squamous cell carcinoma (OSCC), especially as a combined modality approach with and after surgery or radiotherapy. Limited therapeutic efficiency and serious side effects greatly restrict the clinical performance of chemotherapeutic drugs. The development of smart nanomedicines has provided new research directions, to some extent. However, the involvement of complex carrier compositions inevitably brings biosafety concerns and greatly limits the "bench-to-bed" translation of most nanomedicines reported. In this study, a carrier-free self-assembled prodrug was fabricated by two triterpenes (glycyrrhetinic acid, GA and ginsenoside Rh2, Rh2) isolated from medicinal plants, licorice, and ginseng, for the targeted and highly effective treatment of OSCC. Reactive oxygen species (ROS) self-supplied molecule TK-GA2 was synthesized with ROS-responsive thioketal linker and prodrug was prepared by a rapid-solvent-exchange method with TK-GA2 and Rh2. After administration, oral tumor cells transported large amounts of prodrugs with glucose ligands competitively. Endogenous ROS in oral tumor cells then promoted the release of GA and Rh2. GA further evoked the generation of a large number of ROS to help self-boosted drug release and increase oxidative stress, synergistically causing tumor cell apoptosis with Rh2. Overall, this carrier-free triterpene-based prodrug might provide a preeminent opinion on the design of effective chemotherapeutics with low systemic toxicity against OSCC.

Quercetin slow-release system delays starch digestion via inhibiting transporters and enzymes

This study investigates the potential of a quercetin-based emulsion system to moderate starch digestion and manage blood glucose levels, addressing the lack of in vivo research. By enhancing quercetin bioaccessibility and targeting release in the small intestine, the emulsion system demonstrates significant inhibition of starch digestion and glucose spikes through both in vitro and in vivo experiments. The system inhibits α-amylase and α-glucosidase via competitive and mixed inhibition mechanisms, primarily involving hydrogen bonds and van der Waals forces, leading to static fluorescence quenching. Additionally, this system downregulates the protein expression and gene transcription of SGLT1 and GLUT2. These findings offer a novel approach to sustaining glucose equilibrium, providing a valuable foundation for further application of quercetin emulsion in food science.

Polyphenols mediated attenuation of diabetes associated cardiovascular complications: A comprehensive review

Background

Diabetes mellitus is a common chronic metabolic disorder that is characterized by increased levels of glucose for prolonged periods of time. Incessant hyperglycemia leads to diabetic complications such as retinopathy, nephropathy, and neuropathy, and cardiovascular complications such as ischemic heart disease, peripheral vascular disease, diabetic cardiomyopathy, stroke, etc. There are many studies that suggest that various polyphenols affect glucose homeostasis and can help to attenuate the complications associated with diabetes.

Objective

This review focuses on the possible role of various dietary polyphenols in palliating diabetes-induced cardiovascular complications. This review also aims to give an overview of the interrelationship among ROS production (due to diabetes), inflammation, glycoxidative stress, and cardiovascular complications as well as the anti-hyperglycemic effects of dietary polyphenols.

Methods

Various scientific databases including Scopus, Web of Science, Google Scholar, PubMed, Science Direct, Springer Link, and Wiley Online Library were used for searching articles that complied with the inclusion and exclusion criteria.

Results

This review lists several polyphenols based on various pre-clinical and clinical studies that have anti-hyperglycemic potential as well as a protective function against cardiovascular complications.

Conclusion

Several pre-clinical and clinical studies suggest that various dietary polyphenols can be a promising intervention for the attenuation of diabetes-associated cardiovascular complications.

Disulfidptosis, A Novel Cell Death Pathway: Molecular Landscape and Therapeutic Implications

Programmed cell death is pivotal for several physiological processes, including immune defense. Further, it has been implicated in the pathogenesis of developmental disorders and the onset of numerous diseases. Multiple modes of programmed cell death, including apoptosis, pyroptosis, necroptosis, and ferroptosis, have been identified, each with their own unique characteristics and biological implications. In February 2023, Liu Xiaoguang and his team discovered "disulfidptosis," a novel pathway of programmed cell death. Their findings demonstrated that disulfidptosis is triggered in glucose-starved cells exhibiting high expression of a protein called SLC7A11. Furthermore, disulfidptosis is marked by a drastic imbalance in the NADPH/NADP+ ratio and the abnormal accumulation of disulfides like cystine. These changes ultimately lead to the destabilization of the F-actin network, causing cell death. Given that high SLC7A11 expression is a key feature of certain cancers, these findings indicate that disulfidptosis could serve as the basis of innovative anti-cancer therapies. Hence, this review delves into the discovery of disulfidptosis, its underlying molecular mechanisms and metabolic regulation, and its prospective applications in disease treatment.

Enhancing Targeted Photodynamic Therapy: Star-Shaped Glycopolymeric Photosensitizers for Improved Selectivity and Efficacy

Targeted photodynamic therapy (PDT) offers advantages over nontargeted approaches, including improved selectivity, efficacy, and reduced side effects. This study developed star-shaped glycopolymeric photosensitizers using porphyrin-based initiators via ATRP. Incorporating a porphyrin core gave the polymers fluorescence and ROS generation, while adding fructose improved solubility and targeting capabilities. The photosensitizers had high light absorption, singlet oxygen production, specificity, low dark toxicity, and biocompatibility. The glycopolymers with longer sugar arms and higher density showed better uptake on MCF-7 and MDA-MB-468 cells compared to HeLa cells, indicating enhanced targeting capabilities. Inhibition of endocytosis confirmed the importance of the GLUT5 receptor. The resulting polymers exhibited good cytocompatibility under dark conditions and satisfactory PDT under light irradiation. Interestingly, the polymers containing fructose have a GLUT5-dependent elimination effect on the MCF-7 and MDA-MB-468 cells. The intracellular ROS production followed a similar pattern, indicating that the fructose polymer exhibits specific targeting toward cells with GLUT5 receptors.

Hypoglycemic effect and intestinal transport of phenolics-rich extract from digested mulberry leaves in Caco-2/insulin-resistant HepG2 co-culture model

Phenolics of mulberry (Morus alba L.) leaves (MLs) have potential anti-diabetic effects, but they may be chemically modified during gastrointestinal digestion so affect their biological activity. In this study, an in vitro digestion model coupled with Caco-2 monolayer and Caco-2/insulin-resistant HepG2 coculture model were used to study the transport and hypoglycemic effects of phenolics in raw MLs (U-MLs) and solid-fermented MLs (F-MLs). The results of LC-MS/MS analysis showed that the Papp (apparent permeability coefficient, 10-6cm/s) of phenolics in digested MLs ranged from 0.002 ± 0.00 (quercetin 3-O-glucoside) to 60.19 ± 0.67 (ferulic acid), indicating higher phenolic acids absorbability and poor flavonoids absorbability. The Papp values of phenolic extracts of F-MLs in Caco-2 monolayer were significantly higher (p > 0.05) than that of U-MLs. Digested phenolic extracts inhibited the activities of sucrase (60.13 ± 2.03 %) and maltase (82.35 ± 0.78 %) and decreased 9.28 ± 0.84 % of glucose uptake in Caco-2 monolayer. Furthermore, a decrease in the mRNA expression of glucose transporters SGLT1 (0.64 ± 0.18), GLUT2 (0.14 ± 0.02) and the sucrase-isomaltase (0.59 ± 0.00) was observed. In Caco-2/insulin-resistant HepG2 co-culture model, phenolic extracts regulated glucose metabolism by up-regulating the mRNA expressions of IRS1 (9.32-fold), Akt (17.07-fold) and GYS2 (1.5-fold), and down-regulating the GSK-3β (0.22-fold), PEPCK (0.49-fold) and FOXO1 (0.10-fold) mRNA levels. Both U-MLs and F-MLs could improve glucose metabolism, and the partial least squares (PLS) analysis showed that luteoforol and p-coumaric acid were the primary phenolics that strongly correlated with the hypoglycemic ability of MLs. Results suggested that phenolics of MLs can be used as dietary supplements to regulate glucose metabolism.

Antioxidant and Antidiabetic Properties of Phlorotannins from Ascophyllum nodosum Seaweed Extracts

Seaweeds have gained considerable attention in recent years due to their potential health benefits and high contents of bioactive compounds. This review focuses on the exploration of seaweed's health-promoting properties, with particular emphasis on phlorotannins, a class of bioactive compounds known for their antioxidant and antidiabetic properties. Various novel and ecofriendly extraction methods, including solid-liquid extraction, ultrasound-assisted extraction, and microwave-assisted extraction are examined for their effectiveness in isolating phlorotannins. The chemical structure and isolation of phlorotannins are discussed, along with methods for their characterization, such as spectrophotometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and chromatography. Special attention is given to the antioxidant activity of phlorotannins. The inhibitory capacities of polyphenols, specifically phlorotannins from Ascophyllum nodosum against digestive enzymes, such as α-amylase and α-glucosidase, are explored. The results suggest that polyphenols from Ascophyllum nodosum seaweed hold significant potential as enzyme inhibitors, although the inhibitory activity may vary depending on the extraction conditions and the specific enzyme involved. In conclusion, seaweed exhibits great potential as a functional food ingredient for promoting health and preventing chronic diseases. Overall, this review aims to condense a comprehensive collection of high-yield, low-cost, and ecofriendly extraction methods for obtaining phlorotannins with remarkable antioxidant and antidiabetic capacities.

Role of flavonoids in controlling obesity: molecular targets and mechanisms

Obesity presents a major health challenge that increases the risk of several non-communicable illnesses, such as but not limited to diabetes, hypertension, cardiovascular diseases, musculoskeletal and neurological disorders, sleep disorders, and cancers. Accounting for nearly 8% of global deaths (4.7 million) in 2017, obesity leads to diminishing quality of life and a higher premature mortality rate among affected individuals. Although essentially dubbed as a modifiable and preventable health concern, prevention, and treatment strategies against obesity, such as calorie intake restriction and increasing calorie burning, have gained little long-term success. In this manuscript, we detail the pathophysiology of obesity as a multifactorial, oxidative stress-dependent inflammatory disease. Current anti-obesity treatment strategies, and the effect of flavonoid-based therapeutic interventions on digestion and absorption, macronutrient metabolism, inflammation and oxidative stress and gut microbiota has been evaluated. The use of several naturally occurring flavonoids to prevent and treat obesity with a long-term efficacy, is also described.

Synergistic Combination of Citrus Flavanones as Strong Antioxidant and COX-Inhibitor Agent

Recently, we demonstrated that a Citrus flavanone mix (FM) shows antioxidant and anti-inflammatory activity, even after gastro-duodenal digestion (DFM). The aim of this study was to investigate the possible involvement of the cyclooxygenases (COXs) in the anti-inflammatory activity previously detected, using a human COX inhibitor screening assay, molecular modeling studies, and PGE2 release by Caco-2 cells stimulated with IL-1β and arachidonic acid. Furthermore, the ability to counteract pro-oxidative processes induced by IL-1β was evaluated by measuring four oxidative stress markers, namely, carbonylated proteins, thiobarbituric acid-reactive substances, reactive oxygen species, and reduced glutathione/oxidized glutathione ratio in Caco-2 cells. All flavonoids showed a strong inhibitory activity on COXs, confirmed by molecular modeling studies, with DFM, which showed the best and most synergistic activity on COX-2 (82.45% vs. 87.93% of nimesulide). These results were also corroborated by the cell-based assays. Indeed, DFM proves to be the most powerful anti-inflammatory and antioxidant agent reducing, synergistically and in a statistically significant manner (p < 0.05), PGE2 release than the oxidative stress markers, also with respect to the nimesulide and trolox used as reference compounds. This leads to the hypothesis that FM could be an excellent antioxidant and COX inhibitor candidate to counteract intestinal inflammation.

Polyphenolic compounds from rapeseeds (Brassica napus L.): The major types, biofunctional roles, bioavailability, and the influences of rapeseed oil processing technologies on the content

The rapeseed (Brassica napus L.) are the important oil bearing material worldwide, which contain wide variety of bioactive components with polyphenolic compounds considered the most typical. The rapeseed polyphenols encompass different structural variants, and have been considered to have many bioactive functions, which are beneficial for the human health. Whereas, the rapeseed oil processing technologies affect their content and the biofunctional activities. The present review of the literature highlighted the major types of the rapeseed polyphenols, and summarized their biofunctional roles. The influences of rapeseed oil processing technologies on these polyphenols were also elucidated. Furthermore, the directions of the future studies for producing nutritional rapeseed oils preserved higher level of polyphenols were prospected. The rapeseed polyphenols are divided into the phenolic acids and polyphenolic tannins, both of which contained different subtypes. They are reported to have multiple biofunctional roles, thus showing outstanding health improvement effects. The rapeseed oil processing technologies have significant effects on both of the polyphenol content and activity. Some novel processing technologies, such as aqueous enzymatic extraction (AEE), subcritical or supercritical extraction showed advantages for producing rapeseed oil with higher level of polyphenols. The oil refining process involved heat or strong acid and alkali conditions affected their stability and activity, leading to the loss of polyphenols of the final products. Future efforts are encouraged to provide more clinic evidence for the practical applications of the rapeseed polyphenols, as well as optimizing the processing technologies for the green manufacturing of rapeseed oils.

Association of Polyphenols Consumption with Risk for Gestational Diabetes Mellitus and Preeclampsia: A Systematic Review and Meta-Analysis

Gestational Diabetes Mellitus (GDM) and preeclampsia (PE) affects 6-25% of pregnancies and are characterized by an imbalance in natural prooxidant/antioxidant mechanisms. Due to their antioxidant and anti-inflammatory properties, polyphenols consumption during the pregnancy might exert positive effects by preventing GDM and PE development. However, this association remains inconclusive. This systematic review and metanalysis is aimed to analyze the association between polyphenol-rich food consumption during pregnancy and the risk of GDM and PE. A systematic search in MEDLINE, EMBASE, and Web of Science (Clarivate Analytics, London, United Kingdom) for articles dated between 1 January 1980 and July 2022 was undertaken to identify randomized controlled trials and observational studies evaluating polyphenol-rich food consumption and the risk of GDM and PE. The Newcastle-Ottawa Scale was used to evaluate the quality of these included studies. Twelve studies were included, of which eight articles evaluated GDM and four studied PE. A total of 3785 women presented with GDM (2.33%). No association between polyphenol consumption and GDM was found (ES = 0.85, 95% CI 0.71-1.01). When total polyphenol intake was considered, a lower likelihood to develop GDM was noted (ES = 0.78, 95% CI 0.69-0.89). Furthermore, polyphenol consumption was not associated with PE development (ES = 0.90, 95% CI 0.57-1.41). In conclusion, for both outcomes, pooled analyses showed no association with polyphenol-rich food consumption during pregnancy. Therefore, association of polyphenol intake with a decreased risk of GDM and PE remains inconclusive.

Dietary Polyphenols and In Vitro Intestinal Fructose Uptake and Transport: A Systematic Literature Review

Recent evidence links chronic consumption of large amounts of fructose (FRU) with several non-communicable disease. After ingestion, dietary FRU is absorbed into the intestinal tract by glucose transporter (GLUT) 5 and transported to the portal vein via GLUT2. GLUT2 is primarily localized on the basolateral membrane, but GLUT2 may be dislocated post-prandially from the basolateral membrane of intestinal cells to the apical one. Polyphenols (PP) are plant secondary metabolites that exert hypoglycemic properties by modulating intracellular insulin signaling pathways and by inhibiting intestinal enzymes and transporters. Post-prandially, PP may reach high concentrations in the gut lumen, making the inhibition of FRU absorption a prime target for exploring the effects of PP on FRU metabolism. Herein, we have systematically reviewed studies on the effect of PP and PP-rich products on FRU uptake and transport in intestinal cells. In spite of expectations, the very different experimental conditions in the various individual studies do not allow definitive conclusions to be drawn. Future investigations should rely on standardized conditions in order to obtain comparable results that allow a credible rating of polyphenols and polyphenol-rich products as inhibitors of fructose uptake.

Effects of Polyphenols on Glucose-Induced Metabolic Changes in Healthy Human Subjects and on Glucose Transporters

Dietary polyphenols interact with glucose transporters in the small intestine and modulate glucose uptake after food or beverage consumption. This review assesses the transporter interaction in vitro and how this translates to an effect in healthy volunteers consuming glucose. As examples, the apple polyphenol phlorizin inhibits sodium-glucose linked transporter-1; in the intestinal lumen, it is converted to phloretin, a strong inhibitor of glucose transporter-2 (GLUT2), by the brush border digestive enzyme lactase. Consequently, an apple extract rich in phlorizin attenuates blood glucose and insulin in healthy volunteers after a glucose challenge. On the other hand, the olive phenolic, oleuropein, inhibits GLUT2, but the strength of the inhibition is not enough to modulate blood glucose after a glucose challenge in healthy volunteers. Multiple metabolic effects and oxidative stresses after glucose consumption include insulin, incretin hormones, fatty acids, amino acids, and protein markers. However, apart from acute postprandial effects on glucose, insulin, and some incretin hormones, very little is known about the acute effects of polyphenols on these glucose-induced secondary effects. In summary, attenuation of the effect of a glucose challenge in vivo is only observed when polyphenols are strong inhibitors of glucose transporters.

Dietary proanthocyanidins promote localized antioxidant responses in porcine pulmonary and gastrointestinal tissues during Ascaris suum-induced type 2 inflammation

Proanthocyanidins (PAC) are dietary polyphenols with putative anti-inflammatory and immunomodulatory effects. However, whether dietary PAC can regulate type-2 immune function and inflammation at mucosal surfaces remains unclear. Here, we investigated if diets supplemented with purified PAC modulated pulmonary and intestinal mucosal immune responses during infection with the helminth parasite Ascaris suum in pigs. A. suum infection induced a type-2 biased immune response in lung and intestinal tissues, characterized by pulmonary granulocytosis, increased Th2/Th1 T cell ratios in tracheal-bronchial lymph nodes, intestinal eosinophilia, and modulation of genes involved in mucosal barrier function and immunity. Whilst PAC had only minor effects on pulmonary immune responses, RNA-sequencing of intestinal tissues revealed that dietary PAC significantly enhanced transcriptional responses related to immune function and antioxidant responses in the gut of both naïve and A. suum-infected animals. A. suum infection and dietary PAC induced distinct changes in gut microbiota composition, primarily in the jejunum and colon, respectively. Notably, PAC consumption substantially increased the abundance of Limosilactobacillus reuteri. In vitro experiments with porcine macrophages and intestinal epithelial cells supported a role for both PAC polymers and PAC-derived microbial metabolites in regulating oxidative stress responses in host tissues. Thus, dietary PAC may have distinct beneficial effects on intestinal health during infection with mucosal pathogens, while having a limited activity to modulate naturally-induced type-2 pulmonary inflammation. Our results shed further light on the mechanisms underlying the health-promoting properties of PAC-rich foods, and may aid in the design of novel dietary supplements to regulate mucosal inflammatory responses in the gastrointestinal tract.

Role of polyphenols in combating Type 2 Diabetes and insulin resistance

Compromised carbohydrate metabolism leading to hyperglycemia is the primary metabolic disorder of non-insulin-dependent diabetes mellitus. Reformed digestion and altered absorption of carbohydrates, exhaustion of glycogen stock, enhanced gluconeogenesis and overproduced hepatic glucose, dysfunction of β-cell, resistance to insulin in peripheral tissue, and impaired insulin signaling pathways are essential reasons for hyperglycemia. Although oral anti-diabetic drugs like α-glucosidase inhibitors, sulfonylureas and insulin therapies are commonly used to manage Type 2 Diabetes (T2D) and hyperglycemia, natural compounds in diet also play a significant role in combating the effect of diabetes. Due to their vast bioavailability and anti-hyperglycemic effect with least or no side effects, polyphenolic compounds have gained wide popularity. Polyphenols such as flavonoids and tannins play a significant role in carbohydrate metabolism by inhibiting key enzymes responsible for the digestion of carbohydrates to glucose like α-glucosidase and α-amylase. Several polyphenols such as resveratrol, epigallocatechin-3-gallate (EGCG) and quercetin enhanced glucose uptake in the muscle and adipocytes by translocating GLUT4 to plasma membrane mainly by the activation of the AMP-activated protein kinase (AMPK) pathway. This review provides an insight into the protective role of polyphenols in T2D, highlighting the aspects of insulin resistance.

Oenothein B in Eucalyptus Leaf Extract Suppresses Fructose Absorption in Caco-2 Cells

Inhibition of fructose absorption may suppress adiposity and adiposity-related diseases caused by fructose ingestion. Eucalyptus leaf extract (ELE) inhibits intestinal fructose absorption (but not glucose absorption); however, its active compound has not yet been identified. Therefore, we evaluated the inhibitory activity of ELE obtained from Eucalyptus globulus using an intestinal fructose permeation assay with the human intestinal epithelial cell line Caco-2. The luminal sides of a cell monolayer model cultured on membrane filters were exposed to fructose with or without the ELE. Cellular fructose permeation was evaluated by measuring the fructose concentration in the medium on the basolateral side. ELE inhibited 65% of fructose absorption at a final concentration of 1 mg/mL. Oenothein B isolated from the ELE strongly inhibited fructose absorption; the inhibition rate was 63% at a final concentration of 5 μg/mL. Oenothein B did not affect glucose absorption. In contrast, the other major constituents (i.e., gallic acid and ellagic acid) showed little fructose-inhibitory activity. To our knowledge, this is the first report that oenothein B in ELE strongly inhibits fructose absorption in vitro. ELE containing oenothein B can prevent and ameliorate obesity and other diseases caused by dietary fructose consumption.

Ginsenoside as a new stabilizer enhances the transfection efficiency and biocompatibility of cationic liposome

Nucleic acid drugs have emerged as important therapeutics but their clinical application has been greatly limited by their large molecular weight, high polarity, negative charge and short half-life. Cationic liposomes (CLs) have gained wide attention as non-viral vectors for nucleic acid delivery. However, the absolute transfection efficiency of CLs can still be enhanced while their cytotoxicity should be decreased simultaneously. Ginsenosides, obtained from natural plants, possess a similar steroid structure to cholesterol and might be an alternative to cholesterol for acting as a membrane stabilizer of CLs. Herein, seven kinds of ginsenoside-based compounds were utilized to prepare CLs (GCLs) and their efficacy in siRNA delivery was investigated. The particle sizes of the GCLs were 90-300 nm and the siRNA delivery efficiencies were in the range of 23.6%-78.4%. Rg5-based CLs (Rg5-CLs) exhibited the highest transfection efficiency of 81% and the lowest toxicity, with 82% cell viability obtained even at high concentrations. Ginsenosides are shown as promising biomaterials as membrane stabilizers of CLs. Rg5-CLs have been demonstrated as efficient non-viral vectors with high transfection efficiency and good biocompatibility for gene delivery, possessing great potential for gene therapy.

Quercetin improves myocardial redox status in rats with type 2 diabetes

Objective. Emerging data indicate that oxidative stress is closely associated with the pathogenesis of cardiovascular disease in type 2 diabetes mellitus (T2DM). The present study aimed to assess the effect of the most abundant flavonoid in the human diet quercetin (Q) on the myocardial redox status in rats with T2DM. Methods. T2DM was induced in male Wistar rats by a high caloric diet (for 14 weeks) and two streptozotocin (25 mg/kg b.w.) injections applied in four weeks of the diet, once a week for two weeks. The Q was administered intragastrically by gavage in a dose of 10 or 50 mg/kg of the body weight for 8 weeks starting from the 8th day after the last streptozotocin injection. The control rats received citrate buffer and seven days after the last STZ injection, basal glucose levels were measured in all animals. Results. Administration of Q increased insulin sensitivity in diabetic rats with more pronounced effect at a dose of 50 mg/kg b.w. The Q also decreased free radical oxidation in the heart mitochondria of diabetic animals, thus limiting the formation of advanced oxidation protein products in a dose-dependent manner and normalized the activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione reductase) in cardiac mitochondria independently of the dose used. In addition, the Q in both doses prevented the development of oxidative stress in the T2DM rats cardiomyocytes by reducing NADPH oxidase and xanthine oxidase activities. Conclusions. The findings demonstrate that Q in both doses 10 mg/kg and 50 mg/kg can protect from the development of oxidative stress in cardiomyocytes in the diabetic rats. The present data indicate that the use of Q may contribute to the amelioration of cardiovascular risk in patients with T2DM.

Phenolics-Rich Extracts of Dietary Plants as Regulators of Fructose Uptake in Caco-2 Cells via GLUT5 Involvement

The latest data link the chronic consumption of large amounts of fructose present in food with the generation of hypertension and disturbances in carbohydrate and lipid metabolism, which promote the development of obesity, non-alcoholic fatty liver disease, insulin resistance, and type 2 diabetes. This effect is possible after fructose is absorbed by the small intestine cells and, to a lesser extent, by hepatocytes. Fructose transport is dependent on proteins from the family of glucose transporters (GLUTs), among which GLUT5 selectively absorbs fructose from the intestine. In this study, we examined the effect of four phenolic-rich extracts obtained from A. graveolens, B. juncea, and M. chamomilla on fructose uptake by Caco-2 cells. Extracts from B. juncea and M. chamomilla most effectively reduced fluorescent fructose analogue (NBDF) accumulation in Caco-2, as well as downregulated GLUT5 protein levels. These preparations were able to decrease the mRNA level of genes encoding transcription factors regulating GLUT5 expression-thioredoxin-interacting protein (TXNIP) and carbohydrate-responsive element-binding protein (ChREBP). Active extracts contained large amounts of apigenin and flavonols. The molecular docking simulation suggested that some of identified phenolic constituents can play an important role in the inhibition of GLUT5-mediated fructose transport.

Antidiabetic effect of fucoxanthin extracted from Sargassum angustifolium on streptozotocin-nicotinamide-induced type 2 diabetic mice

This work aimed to study the antidiabetic effect of encapsulated fucoxanthin with porous starch (PS) in streptozotocin and nicotinamide-induced type 2 diabetic mice. Fucoxanthin was extracted and purified from Sargassum angustifolium and encapsulated in porous starch (PS). Diabetic mice groups were gavaged daily with fucoxanthin (400 mg/kg), either free or encapsulated into PS, and metformin (50 mg/kg) for three weeks. The results exhibited that the fucoxanthin and fucoxanthin-loaded PS markedly prevented the weight gain in treated groups (p < .05). Moreover, both free and encapsulated fucoxanthin could decrease the fasting blood glucose and increase the plasma insulin level similar to metformin (p < .05). In addition, total cholesterol, triglyceride, and low-density lipoprotein were lower in the treated groups. These results confirm antiobesity effect of fucoxanthin by regulating lipid profile parameters. Moreover, the histopathology evaluation of pancreatic tissue in diabetic mice exhibited that oral administration of metformin and fucoxanthin caused regeneration of pancreatic beta cells. This study revealed the healthy effect of seaweed pigment as a suitable bioactive compound which can be used in functional foods for natural diabetes therapy.

Inhibition of the intestinal postprandial glucose transport by gallic acid and gallic acid derivatives

Inhibition of glucose uptake in the intestine through sodium-dependent glucose transporter 1 (SGLT1) or glucose transporter 2 (GLUT2) may be beneficial in controlling postprandial blood glucose levels. Gallic acid and ten of its derivatives were identified in the active fractions of Terminalia chebula Retz. fructus immaturus, a popular edible plant fruit which has previously been associated with the inhibition of glucose uptake. Gallic acid derivatives (methyl gallate, ethyl gallate, pentyl gallate, 3,4,6-tri-O-galloyl-β-d-glucose, and corilagin) showed good glucose transport inhibition with inhibitory rates of 72.1 ± 1.6%, 71.5 ± 1.4%, 79.9 ± 1.2%, 44.7 ± 1.2%, and 75.0 ± 0.7% at 5 mM d-glucose and/or 56.3 ± 2.3, 52.1 ± 3.2%, 70.2 ± 1.7%, 15.6 ± 1.6%, and 37.1 ± 0.8% at 25 mM d-glucose. However, only 3,4,6-tri-O-galloyl-β-d-glucose and corilagin were confirmed GLUT2-specific inhibitors. Whilst some tea flavonoids demonstrated minimal glucose transport inhibition, their gallic acid derivatives strongly inhibited transport effect with GLUT2 specificity. This suggests that gallic acid structures are crucial for glucose transport inhibition. Plants, such as T. chebula, which contain high levels of gallic acid and its derivatives, show promise as natural functional ingredients for inclusion in foods and drinks designed to control postprandial glucose levels.

Protection against developing type 2 diabetes by coffee consumption: assessment of the role of chlorogenic acid and metabolites on glycaemic responses

Epidemiological studies show a convincing long-term and dose-dependent protection of coffee and decaffeinated coffee against developing type 2 diabetes. The mechanisms of this effect are still not understood even though several have been proposed, including a potential effect on blood glucose by chlorogenic acids. However, there is minimal effect of decaffeinated coffee on postprandial blood glucose and insulin when consumed with carbohydrates, although there may be effects on incretin hormones, but these have been measured in only a few studies. Although chlorogenic acids do not affect carbohydrate digestion directly, they may affect glucose absorption and subsequent utilisation, the latter through metabolites derived from endogenous pathways or action of the gut microbiota. To advance understanding of the protective effect of coffee chlorogenic acids, more chronic intervention studies are needed on decaffeinated coffee, coupled with mechanistic studies in vitro using more realistic concentrations of the relevant chlorogenic acid metabolites.

Effects of Polyphenols on Insulin Resistance

Insulin resistance (IR) is apparent when tissues responsible for clearing glucose from the blood, such as adipose and muscle, do not respond properly to appropriate signals. IR is estimated based on fasting blood glucose and insulin, but some measures also incorporate an oral glucose challenge. Certain (poly)phenols, as supplements or in foods, can improve insulin resistance by several mechanisms including lowering postprandial glucose, modulating glucose transport, affecting insulin signalling pathways, and by protecting against damage to insulin-secreting pancreatic β-cells. As shown by intervention studies on volunteers, the most promising candidates for improving insulin resistance are (-)-epicatechin, (-)-epicatechin-containing foods and anthocyanins. It is possible that quercetin and phenolic acids may also be active, but data from intervention studies are mixed. Longer term and especially dose-response studies on mildly insulin resistant participants are required to establish the extent to which (poly)phenols and (poly)phenol-rich foods may improve insulin resistance in compromised groups.

Recent advances in extracting phenolic compounds from food and their use in disease prevention and as cosmetics

Phenolic compounds in plants are essential components of human nutrition, which provide various health benefits. However, some missing links became the research in phenolic compounds structures and potential applications in a challenging work. Despite universal extraction methods with mixtures of different organic solvents are generally adopted in the analysis of phenolic compounds, a need for establish a specific procedure is still open. The great heterogeneity in food and food by-products matrices and the lack of standardized methods which combine chromatographic with spectrophotometric techniques to calculate the amount of phenolic compounds joined with the absence of specific standards hamper to accurate know the real amount of phenolic compounds. Indeed, the high complexity in nature and chemistry of phenolic compounds clearly difficult to establish a daily intake to obtain certain healthy outcomes. Hence, despite the potential of phenolic compounds to use them in cosmetic and healthy applications have been widely analyzed, some concerns must be considered. The chemical complexity, the interactions between phenolic compounds and other food components and the structural changes induced by food processing joined with the lack in the understanding of phenolic compounds metabolism and bioavailability undergo the need to conduct a comprehensive review of each factors influencing the final activity of phenolic compounds. This paper summarizes the potential of phenolic compounds for disease prevention and cosmetics production, as well as their many other uses derived from their antioxidant activity. This paper illustrates the potential of phenolic compounds for disease prevention and cosmetics production, as well as their many other uses derived from their antioxidant activity.

Intestinal Fructose and Glucose Metabolism in Health and Disease

The worldwide epidemics of obesity and diabetes have been linked to increased sugar consumption in humans. Here, we review fructose and glucose metabolism, as well as potential molecular mechanisms by which excessive sugar consumption is associated to metabolic diseases and insulin resistance in humans. To this end, we focus on understanding molecular and cellular mechanisms of fructose and glucose transport and sensing in the intestine, the intracellular signaling effects of dietary sugar metabolism, and its impact on glucose homeostasis in health and disease. Finally, the peripheral and central effects of dietary sugars on the gut-brain axis will be reviewed.

Plant-derived glucose transport inhibitors with potential antitumor activity

Glucose, a key nutrient utilized by human cells to provide cellular energy and a carbon source for biomass synthesis, is internalized in cells via glucose transporters that regulate glucose homeostasis throughout the human body. Glucose transporters have been used as important targets for the discovery of new drugs to treat cancer, diabetes, and heart disease, owing to their abnormal expression during these disease conditions. Thus far, several glucose transport inhibitors have been used in clinical trials, and increasing numbers of natural products have been characterized as potential anticancer agents targeting glucose transport. The present review focuses on natural product glucose transport inhibitors of plant origin, including alkaloids, flavonoids and other phenolic compounds, and isoprenoids, with their potential antitumor properties also discussed.

Novel ginsenoside-based multifunctional liposomal delivery system for combination therapy of gastric cancer

The clinical treatment of gastric cancer (GC) is hampered by the development of anticancer drug resistance and the unfavorable pharmacokinetics, off-target toxicity, and inadequate intratumoral accumulation of the current chemotherapy treatments. Ginsenosides combined with paclitaxel (PTX) have been shown to exert synergistic inhibition of human GC cell proliferation. In the present study, we developed a novel multifunctional liposome system, in which ginsenosides functioned as the chemotherapy adjuvant and membrane stabilizer. These had long blood circulation times and active targeting abilities, thus creating multifunctionality of the liposomes and facilitating drug administration to the GC cells. Methods: Three ginsenosides with different structures were used to formulate the unique nanocarrier, which was prepared using the thin-film hydration method. The stability of the ginsenoside liposomes was determined by particle size analysis using dynamic light scattering. The long circulation time of ginsenoside liposomes was compared with that of conventional liposome and polyethylene glycosylated liposomes in vivo. The active targeting effect of ginsenoside liposomes was examined with a GC xenograft model using an in vivo imaging system. To examine the antitumor activity of ginsenoside liposomes against GC, MTT, cell cycle, and apoptosis assays were performed on BGC-823 cells in vitro and PTX-loaded ginsenoside liposomes were prepared to evaluate the therapeutic efficacy on GC in vivo. Results: The ginsenosides stabilized the liposomes in a manner similar to cholesterol. We confirmed the successful delivery of the bioactive combination drugs and internalization into GC cells via analysis of the glucose-related transporter recognition and longer blood circulation time. PTX was encapsulated in different liposomal formulations for use as a combination therapy, in which ginsenosides were found to exert their inherent anticancer activity, as well as act synergistically with PTX. The combination therapy using these targeted liposomes significantly suppressed GC tumor growth and outperformed most reported PTX formulations, including Lipusu® and Abraxane®. Conclusion: We established novel ginsenoside-based liposomes as a tumor-targeting therapy, in which ginsenoside functioned not only as a chemotherapy adjuvant, but also as a functional membrane material. Ginsenoside-based liposomes offer a novel platform for anticancer drug delivery and may lead to a new era of nanocarrier treatments for cancer.

Postgenomic Properties of Natural Micronutrients

Modern medical approaches to the therapy of various diseases, including cancer, are based on the use of toxic drugs. The unfavorable side effects of traditional medicine could be counterbalanced by addition of natural bioactive substances to conventional therapy due to their mild action on cells combined with the multitargeted effects. To elucidate the real mechanisms of their biological activity, versatile approaches including a number of "omics" such as genomics, transcriptomics, proteomics, and metabolomics are used. This review highlights inclusion of bioactive natural compounds into the therapy of chronic diseases from the viewpoint of modern omics-based nutritional biochemistry. The recently accumulated data argue for necessity to employ nutrigenetic and nutrimetabolomic analyses to prevent or diminish the risk of chronic diseases.