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

Assessing the impact of food-derived bioactives on digestive proteases by in vitro and in silico approaches

The interactions between food components and digestive tract enzymes can affect nutrient absorption and impact an individual's health. Certain components, particularly polyphenols, are reported to inhibit digestive enzymes and are commonly referred to as anti-nutritional factors. Reports on this subject often contradict each other, highlighting the need for consistent methodologies to assess the potential impact of bioactive compounds. This study evaluated the "in vitro" activity of pepsin, trypsin, and chymotrypsin using ovalbumin, gluten, and haemoglobin as substrates in the presence or absence of twenty-five bioactive natural compounds belonging to different chemical classes at gastro-intestinal physiological concentrations (0.1 mM). The results indicate that bioactives may have opposite effects on proteolytic activity depending on the substrate/enzyme combination and bioactives structure. With ovalbumin as substrate, piceid and resveratrol were described as strong chymotrypsin activators (+1.46- and 1.17-fold change, respectively), phloridzin dihydrate as a weaker activator (+0.41-fold change), while phloretin was a strong inhibitor (-0.65-fold change). A computational approach based on molecular docking and dynamics simulations was used to investigate the interactions between selected bioactives, chymotrypsin and ovalbumin. The "in silico" study included piceid and phloridzin dihydrate, as well as their respective aglycones (resveratrol and phloretin). The results obtained through computational modelling indicate that all four bioactives can interact with chymotrypsin. However, only those bioactives that enhance in vitro proteolytic activity induce a partial unfolding of ovalbumin's structure. This suggests that the effect of bioactive compounds on protein digestion may be substrate-dependent, and may vary depending on the specific protein being digested.

Egyptian aquaponic celery (Apium graveolens): Phenolic and volatile profiles analysed using HPLC-MS/ms and gc-ms/ms

Recently, water scarcity has been a substantial problem facing agriculture in Egypt, with a great impact on food security and hence makes it a challenge to satisfy food demand. An aquaponic system with minimum water needs is considered a substitute technique to meet the demand of food shortages. Celery (Apium graveolens) is a widely cultivated herb belonging to the family Apiaceae and widely consumed as a popular ingredient in a wide range of dishes and food recipes. A total of 13 phenolic metabolites were detected and quantified using HPLC-ESI-MS/MS. Chlorogenic acid was detected as the most abundant phenolic compound accounting for 3471.58 mg kg-1. Moreover, 65 volatile compounds belonging to 12 different classes were detected using GS-MS with an abundance of aromatic hydrocarbons at ca.68.15%. and the main constituents were 6-phenyltridecane, 6-phenyldodecane, and 5-phenylundecane at ca.6.78%, 6.62%, and 6.13% respectively. It is the first time to report metabolic profile in celery grown in an aquaponic system.

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.

GLUT5: structure, functions, diseases and potential applications

Glucose transporter 5 (GLUT5) is a membrane transporter that specifically transports fructose and plays a key role in dietary fructose uptake and metabolism. In recent years, a high fructose diet has occupied an important position in the daily intake of human beings, resulting in a significant increase in the incidence of obesity and metabolic diseases worldwide. Over the past few decades, GLUT5 has been well understood to play a significant role in the pathogenesis of human digestive diseases. Recently, the role of GLUT5 in human cancer has received widespread attention, and a large number of studies have focused on exploring the effects of changes in GLUT5 expression levels on cancer cell survival, metabolism and metastasis. However, due to various difficulties and shortcomings, the molecular structure and mechanism of GLUT5 have not been fully elucidated, which to some extent prevents us from revealing the relationship between GLUT5 expression and cell carcinogenesis at the protein molecular level. In this review, we summarize the current understanding of the structure and function of mammalian GLUT5 and its relationship to intestinal diseases and cancer and suggest that GLUT5 may be an important target for cancer therapy.

Trichostatin a inhibits expression of the human SLC2A5 gene via SNAI1/SNAI2 transcription factors and sensitizes colon cancer cells to platinum compounds

GLUT5, a key protein encoded by the SLC2A5 gene, is involved in the uptake of fructose from the intestine. Currently, with the increased consumption of this sugar and the associated increased incidence of obesity, diabetes and cancer, GLUT5 may represent an important molecular target in the prevention and treatment of these diseases. Here, we demonstrate that overexpression of the SNAI1 and SNAI2 transcription factors in cells expressing high levels of SLC2A5 mRNA reduced SLC2A5 gene expression. Furthermore, a histone deacetylase inhibitor, trichostatin A, which induces SNAI1 and SNAI2 expression, inhibits SLC2A5/GLUT5 expression and sensitizes colon cancer cells to cisplatin and oxaliplatin. This finding might have potential relevance for the development of therapeutic treatments aimed at modulating fructose transport or genes involved in this process for use with certain cancers.

Physiological effects of food ingredients on intestinal epithelial cell function

Understanding the physiological effects of food ingredients on bodily functions is crucial for the development of foods for specified health use (FoSHU) and functional foods. To investigate this, intestinal epithelial cells (IECs) have been widely studied as they are most frequently exposed to the highest concentrations of food ingredients. Among the various functions of IECs, in this review, we have discussed glucose transporters and their involvement in preventing metabolic syndromes such as diabetes. Phytochemicals are also discussed, as they significantly inhibit glucose and fructose absorption via sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 5 (GLUT5), respectively. Additionally, we have focused on the barrier functions of IECs against xenobiotics. Phytochemicals induce detoxification of metabolizing enzymes via pregnane X receptor or aryl hydrocarbon receptor activation, which suggests that food ingredients can enhance barrier function. This review will provide insights into the role of food ingredients and glucose transporters, as well as detoxification metabolizing enzymes in IECs, and help guide future research on these aspects.

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.

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.