Anthocyanins protect the gastrointestinal tract from high fat diet-induced alterations in redox signaling, barrier integrity and dysbiosis

Cyanidin-3-glucoside improves cognitive impairment in naturally aging mice by modulating the gut microbiota and activating the ERK/CREB/BDNF pathway

Aging-related cognitive impairment has emerged as a major health-threatening factor among the elderly, and cyanidin-3-glucoside (C3G) is a prominent anthocyanin with biological activities, including antioxidant, anti-inflammatory, and alleviation of neurodegeneration. However, the role of C3G in alleviating natural aging-induced cognitive impairment and the underlying mechanisms thereof remain unclear. In this study, experimental methods mainly included biochemical analysis, pathological analysis, immunofluorescence staining, transmission electron microscopy analysis, western blot, as well as the determination of the gut microbiota composition and detection of metabolites. We found that C3G may exert neuroprotective effects and promote brain health by alleviating brain atrophy and neuroinflammation, enhancing brain antioxidant capacity, regulating neurotransmitter expression and hypothalamic-pituitary-adrenal axis activity, and attenuating blood-brain barrier and hippocampal synaptic damage. Furthermore, C3G also promotes gut health by decreasing inflammatory responses and intestinal tissue crypt damage, upregulating the expression of tight junction proteins, and attenuating intestinal damage. Notably, C3G regulated the microbiota composition in different intestinal segments and intestinal mucosa, as well as the metabolic homeostasis of gut microbiota metabolites, such as short-chain fatty acids (SCFAs), amino acids, and bile acids. Substantially increased levels of SCFAs could activate the extracellular signal-regulated kinase (ERK)/cAMP response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling pathway by acting on the G protein-coupled receptors. Correlation analysis indicated that increased gut microbiota, such as Faecalibaculum and Bifidobacterium, and elevated SCFAs were positively correlated with behavioral improvement and brain health. In conclusion, our findings reveal that C3G has the potential to improve natural aging-induced cognitive impairment by modulating the gut microbiota and its metabolite SCFAs, thereby activating the ERK/CREB/BDNF pathway.

Red light induced seed germination and seedling growth by modulating antioxidant defense system, Rubisco, and NADPH oxidase activities in Capsicum frutescens

In this study, the impact of light-emitting diodes (LEDs) in different spectrums was investigated on the seed germination and post-germinative performance of Capsicum frutescens seedlings. The seeds were exposed to different LED lights (full spectrum, white, red, blue, and red-blue) for 0, 1, 2, and 4 h (h). The seeds were placed for a week in darkness to investigate germination, and then the growth mechanisms were studied in four-week-old seedlings. Results indicated that germination percentage was promoted markedly under 2 h red and full lights and also in 1 h blue, which was accompanied by the regulation of H2O2 level and NADPH oxidase (NOX) activity. Sprout growth and height were more heightened under 2 h red light, but their contents decreased considerably under blue light with a rising incubation time. Red light induced more biomass yield, chlorophyll (Chl) pigments, Chl a/b ratio and florescence in four-week-old seedlings. Blue light also increased Chl pigments, but decreased biomass yield by enhancing malondialdehyde (MDA) level. Increased growth in seedlings treated to red light was associated with upregulating Rubisco gene expressions (rbcL and rbcS) and its activity. Red and red-blue lights promoted the activity of superoxide dismutase, glutathione reductase, and ascorbate peroxidase enzymes to increase ascorbic acid (ASA) production in the ascorbate-glutathione cycle. Total phenolic (0.22 mg DAG g- 1 DW), ASA (89.58 mg 100 g- 1 FW) and capsaicinoids (2.73 mg g- 1 DW) contents were heightened under red light, while carotenoid (11.78 µg g- 1 FW) content was more accumulated under blue light. The findings of this study suggest red light modulates NOX activity and H2O2 level for inducing seed germination and seedling quality in C. frutescens, which can create important implications for the production of antioxidant metabolites and increase the cultivation area of this plant.

Androgen deficiency-induced loss of Lactobacillus salivarius extracellular vesicles is associated with the pathogenesis of osteoporosis

Male osteoporosis is primarily caused by a decrease in testicular testosterone production. Male osteoporosis remains a disease with insufficient diagnosis and treatment, and its consequences are severe, especially in older patients. The gut microbiota plays a crucial role in its occurrence and development. Our study found that the relative abundance of Lactobacillus salivarius in the fecal microbiota of male patients with osteoporosis was significantly lower than that in healthy volunteers. Animal experiments have shown that orchiectomy (ORX) can induce osteoporosis and disrupt the intestinal mucosal barrier, and intestinal microbiota. In addition, we discovered a potential etiological connection between the decreased abundance of the intestinal bacterium L. salivarius and the occurrence of ORX-induced osteoporosis. Cohousing or direct colonization of the intestinal microbiota from healthy rats or direct oral administration of the bacteria alleviated ORX-induced osteoporosis and repaired the intestinal mucosal barrier. Finally, we demonstrated that the extracellular vesicles (EVs) of L. salivarius could be transported to the bones and mitigate ORX-induced osteoporosis in rats. Our results indicate that the gut microbiota participates in protecting bones by secreting and delivering bacterial EVs, and that the reduction of L. salivarius and its EVs is closely related to the development of androgen deficiency-related osteoporosis.

Grape pomace extract attenuates high fat diet-induced endotoxemia and liver steatosis in mice

Obesity is a prominent global health concern associated with chronic inflammation and metabolic disorders, such as insulin resistance, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). Excessive consumption of saturated fats exacerbates these conditions by increasing intestinal barrier permeability and circulating endotoxins. This study aims to investigate, in a murine model of high-fat diet (HFD)-induced obesity, the potential beneficial effects of a grape pomace extract (GPE), rich in phenolic compounds, at mitigating endotoxemia, and liver steatosis. Underlying mechanisms were characterized in an in vitro model of intestinal inflammation and permeabilization, as induced by tumor necrosis factor alpha (TNFα) in Caco-2 cell monolayers. Consumption of a HFD (60% calories from fat) for 13 weeks induced obesity, insulin resistance, and liver damage, evidenced by higher levels of plasma alanine aminotransferase (ALT), hepatic triglycerides content, and steatosis. In addition, HFD caused metabolic endotoxemia, hepatic toll-like receptor 4 (TLR4) upregulation and inflammation. GPE supplementation significantly reduced body weight and subcutaneous and visceral adipose tissue weight, and attenuated metabolic dysregulation. Furthermore, GPE decreased circulating LPS levels and mitigated HFD-mediated hepatic TLR4 upregulation, nuclear factor kappa B (NF-κB) activation, and downstream expression of proteins involved in oxidative stress and inflammation (NOX4, TNFα, and F4/80). In Caco-2 cells, GPE mitigated TNFα-induced monolayer permeabilization, decreased tight junction (TJ) protein levels, enhanced cellular oxidant production, activated redox-sensitive signaling, i.e., NF-κB and ERK1/2, and increased NOX1 and MLCK mRNA levels, the latter being a key regulator of monolayer permeability. The above findings suggest that GPE may protect against HFD-induced obesity and associated metabolic dysfunction (insulin resistance and NAFLD) by modulating intestinal barrier integrity and related endotoxemia.

The influence of fruit juice extracts on glucose intestinal transporters and antioxidant genes in a Caco-2 and HT29-MTX co-culture cell system

In recent years, the interest of consumers in fruit juice extracts as nutraceuticals has increased. Fruits, especially red berries, contain valuable bioactive compounds such as polyphenols. Polyphenols are often associated with anti-oxidant, anti-inflammatory, anti-diabetic, anti-cancer, cardioprotective and gastroprotective properties. However, the relationship between the various effects of fruit juice extracts and their influence on the permeability of the intestinal barrier, as well as their influence on glucose transport across the intestinal membrane, is not known. Therefore, in the present study, anthocyanins and copigments were obtained from 11 fruit juice extracts by XAD7 column chromatography and characterized their health-promoting effects, as well as their influence on the intestinal membrane. Chokeberry, pomegranate and blueberry extracts showed the highest antioxidant activity, but showed incomplete regeneration of the intestinal membrane upon treatment-induced higher permeability. This may depended on the high anthocyanin level of these extracts. Treatments with gojiberry extract, elderberry extract and the copigment fraction of apple achieved the best suitable regeneration of the intestinal barrier. The transcription of epithelial glucose transporters GLUT1 und GLUT2 as well as for the oxidative stress genes catalase (CAT) and superoxide dismutase (SOD) were most effectively reduced by chokeberry extract. To sum up, fruit juice extracts possess high antioxidant potentials and can reduce the expression of antioxidant enzymes and glucose transporters in colon cells. While the glucose uptake may be reduced, the intestinal permeability is increased, which varies due to the extract composition. Therefore, fruit juice extracts need to be fractionated and characterized in more detail to identify the health-beneficial compounds.

Intestinal stearoyl-coenzyme A desaturase-inhibition improves obesity-associated metabolic disorders

Stearoyl-coenzyme A desaturase 1 (SCD1) catalyzes the rate-limiting step of de novo lipogenesis and modulates lipid homeostasis. Although numerous SCD1 inhibitors were tested for treating metabolic disorders both in preclinical and clinic studies, the tissue-specific roles of SCD1 in modulating obesity-associated metabolic disorders and determining the pharmacological effect of chemical SCD1 inhibition remain unclear. Here a novel role for intestinal SCD1 in obesity-associated metabolic disorders was uncovered. Intestinal SCD1 was found to be induced during obesity progression both in humans and mice. Intestine-specific, but not liver-specific, SCD1 deficiency reduced obesity and hepatic steatosis. A939572, an SCD1-specific inhibitor, ameliorated obesity and hepatic steatosis dependent on intestinal, but not hepatic, SCD1. Mechanistically, intestinal SCD1 deficiency impeded obesity-induced oxidative stress through its novel function of inducing metallothionein 1 in intestinal epithelial cells. These results suggest that intestinal SCD1 could be a viable target that underlies the pharmacological effect of chemical SCD1 inhibition in the treatment of obesity-associated metabolic disorders.

Amelioration of Obesity-Related Disorders in High-Fat Diet-Fed C57BL/6 Mice Following Fecal Microbiota Transplantation From DL-Norvaline-Dosed Mice

Fecal microbiota transplantation (FMT) could significantly alter the recipient's gut bacteria composition and attenuate obesity and obesity-related metabolic syndromes. DL-norvaline is a nonproteinogenic amino acid and possesses anti-obesity potential. However, the specific mechanisms by which gut microbiota might mediate beneficial effects of DL-norvaline have not been completely elucidated. In this study, DL-norvaline-mediated FMT upregulated the beneficial bacteria (Clostridia_UCG_014, Christensenellales, Bacilli, Ileibacterium, Dubosiella, Lactobacillus, Muribaculaceae, and Bacteroidaceae) and downregulated the harmful bacteria (Tuzzerella and Marinifilaceae), further intestinal inflammation, oxidative stress, and intestinal barrier were alleviated as well as short chain fatty acids levels were increased, thus alleviating glucose and insulin metabolism, improving biochemical indexes and energy metabolism and decreasing body weight gain and tissue weight. However, heat-inactivated FMT did not demonstrate any of those improvements in obese mice. Notably, both DL-norvaline-mediated FMT and heat-inactivated FMT increased Bacteroidaceae and Muribaculaceae, this being a signature of alterations to the gut microbiota marker caused by DL-norvaline. Therefore, the beneficial effects of DL-norvaline were transmissible via FMT. This study highlighted the pivotal involvement of the gut microbiota in the development of obesity and provided a novel insight into the underlying mechanisms of FMT, thereby potentially enhancing the efficacy and refinement of FMT utilization.

Evaluating the Efficacy of Secondary Metabolites in Antibiotic-Induced Dysbiosis: A Narrative Review of Preclinical Studies

BACKGROUND/OBJECTIVES

Drug-induced dysbiosis, particularly from antibiotics, has emerged as a significant contributor to chronic diseases by disrupting gut microbiota composition and function. Plant-derived secondary metabolites, such as polysaccharides, polyphenols, alkaloids, and saponins, show potential in mitigating antibiotic-induced dysbiosis. This review aims to consolidate evidence from preclinical studies on the therapeutic effects of secondary metabolites in restoring gut microbial balance, emphasizing their mechanisms and efficacy.

METHODS

A narrative review was conducted using PubMed, Scopus, and Web of Science. Studies were selected based on specific inclusion criteria, focusing on animal models treated with secondary metabolites for antibiotic-induced dysbiosis. The search terms included "gut microbiota", "antibiotics", and "secondary metabolites". Data extraction focused on microbial alterations, metabolite-specific effects, and mechanisms of action. Relevant findings were systematically analyzed and summarized.

RESULTS

Secondary metabolites demonstrated diverse effects in mitigating the impact of dysbiosis by modulating gut microbial composition, reducing inflammation, and supporting host biological markers. Polysaccharides and polyphenols restored the Firmicutes/Bacteroidetes ratio, increased beneficial taxa such as Lactobacillus and Bifidobacterium, and suppressed pathogenic bacteria like Escherichia-Shigella. Metabolites such as triterpenoid saponins enhanced gut barrier integrity by upregulating tight junction proteins, while alkaloids reduced inflammation by modulating proinflammatory cytokines (e.g., TNF-α, IL-1β). These metabolites also improved short-chain fatty acid production, which is crucial for gut and systemic health. While antibiotic-induced dysbiosis was the primary focus, other drug classes (e.g., PPIs, metformin) require further investigation.

CONCLUSIONS

Plant-derived secondary metabolites show promise in managing antibiotic-induced dysbiosis by restoring microbial balance, reducing inflammation, and improving gut barrier function. Future research should explore their applicability to other types of drug-induced dysbiosis and validate findings in human studies to enhance clinical relevance.

Comprehensive Analysis of Fecal Microbiome and Metabolomics Uncovered dl-Norvaline-Ameliorated Obesity-Associated Disorders in High-Fat Diet-Fed Obese Mice by Targeting the Gut Microbiota

Norvaline is a nonproteinogenic amino acid and an important food ingredient supplement for healthy food. In this study, dl-norvaline administration reduced body weight by more than 40% and improved glucose metabolism and energy metabolism in obese mice induced by a high-fat diet (HFD). Combination analysis of microbiome and metabolomics showed that dl-norvaline supplementation regulated gut bacteria structure, such as increasing beneficial bacteria (Mollicutes_RF39, Ruminococcaceae, Bacteroidaceae, Rikenellaceae, Lactobacillaceae, Clostridiaceae_1, uncultured_bacterium_f_Muribaculaceae, and Rikenellaceae_RC9_gut_group) and decreasing harmful bacteria (Fusobacteriia, Desulfovibrionales, Enterobacteriaceae, Burkholderiaceae, Helicobacteraceae, and Veillonellaceae) and modulated the metabolites involved in arachidonic acid metabolism, thus further promoting short-chain fatty acid production and improving gut barrier, thereby inflammatory responses and oxidative stress were ameliorated. In addition, the pseudogerm-free mouse model verified that dl-norvaline ameliorated obesity-associated disorders in HFD-fed obese mice by targeting gut microbiota. These results clarified that dl-norvaline may be promising for developing and innovating potential functional food products.

Natural Products and Diabetes: (-)-Epicatechin and Mechanisms Involved in the Regulation of Insulin Sensitivity

Type 2 diabetes (T2D) is a disease that occurs when cells do not respond normally to insulin, a condition called insulin resistance, which leads to high blood glucose levels. Although it can be treated pharmacologically, dietary habits beyond carbohydrate restriction can be highly relevant in the management of T2D. Emerging evidence supports the possibility that natural products (NPs) could contribute to managing blood glucose or counteract the undesirable effects of hyperglycemia and insulin resistance. This chapter summarizes the relevant preclinical evidence involving the flavonoid (-)-epicatechin (EC) in the optimization of glucose homeostasis, reducing insulin resistance and/or diabetes-associated disorders. Major effects of EC are observed on (i) intestinal functions, including digestive enzymes, glucose transporters, microbiota, and intestinal permeability, and (ii) redox homeostasis, including oxidative stress and inflammation. There is still a need for further clinical studies to confirm the in vitro and rodent data, allowing recommendations for EC, particularly in prediabetic and T2D patients. The collection of similar data and the lack of clinical evidence for EC is also applicable to other NPs.

Dietary ω-3 Fatty Acids Mitigate Intestinal Barrier Integrity Alterations in Mice Fed a High-Fat Diet: Implications for Pancreatic Carcinogenesis

BACKGROUND

Although body fatness is a recognized risk factor for pancreatic ductal adenocarcinoma (PDAC), the underlying mechanisms of how fat composition affects pancreatic carcinogenesis are poorly understood. High-fat diets (HFDs) can disrupt intestinal barrier function, potentially accelerating carcinogenesis. Omega-3 (ω-3) polyunsaturated fatty acids (FAs) have anti-inflammatory properties and help preserve intestinal integrity.

OBJECTIVE

The objective of this study was to evaluate how ω-3 FAs affect the colonic barrier in the context of HFD-induced changes, in a mouse model of PDAC [p48-Cre; LSL-KrasG12D (KC)].

METHODS

Male and female KC mice were randomly assigned into 1 of the following 4 groups: 1) a control diet containing ∼11% total calories from fat with an ω-6:ω-3 FA ratio of 10:1 (C), 2) the control diet with high concentrations of ω-3 FA with an ω-6:ω-3 FA ratio of 1:1 (Cω3), 3) an HFD containing 60% total calories from fat with an ω-6:ω-3 FA ratio of approximately 10:1 (HF), and 4) an HFD with high concentrations of ω-3 FA with an ω-6:ω-3 FA ratio of 1:1 (HFω3).

RESULTS

Consumption of an HFD for 8 wk caused: 1) disruption of tight junction structure and function; 2) decreased goblet cell number; 3) higher colonic Toll-like receptor 4 (TLR4) and NADPH oxidase 1 expression; 4) activation of TLR4-triggered pathways, that is, NF-κB, c-Jun N-terminal kinase; 5) elevated plasma lipopolysaccharide concentrations; and 6) higher pancreatic TLR4 expression, and 7) accelerated acinar-to-ductal metaplasia. All of these events were mitigated in mice fed the HFω3.

CONCLUSIONS

Our findings support the concept that, in the context of obesity, ω-3 FAs have protective effects during early-stage pancreatic carcinogenesis through the regulation of intestinal permeability and endotoxemia.

Etiolated-green tea attenuates colonic barrier dysfunction and inflammation in high-fat diet-induced mice by modulating gut microbiota

Colonic barrier dysfunction and inflammation arising from dysbiosis gut microbiota (GM) are strongly associated with a high-fat diet (HFD). Yellow leaf green tea (YLGT), a novel variety of etiolated-green tea, improving the intestinal barrier and inflammation is related to the regulation of GM disorders. To explore the ameliorative mechanism of YLGT, mice were fed an HFD with or without YLGT at doses of 150, 300, and 450 mg kg-1 for 12 weeks. YLGT rectified the GM imbalance, enriched short-chain fatty acid (SCFA)-producing bacteria and gut SCFA contents, activated G protein-coupled receptors, inhibited TLR4/NF-κB signaling pathway, strengthened the tight junction, and repaired the damaged intestinal barrier. The fecal microbiota transplantation experiment further confirmed that the GM was a key element in the anti-obesity and anti-intestinal inflammation effect of YLGT. YLGT has great promise in attenuating obesity-induced intestinal dysfunction. This research provides novel insights into the new mechanism of YLGT on HFD-induced obesity.

Antioxidant Activity of Anthocyanins and Anthocyanidins: A Critical Review

Anthocyanins are the main plant pigments responsible for the color of flowers, fruits, and vegetative organs of many plants, and are applied also as safe food colorants. They are efficient antioxidants. In this review, the reactivity of anthocyanins and their aglycones, anthocyanidins, in the main antioxidant assays, and their reactions with reactive oxygen and nitrogen species, effects of interactions with other compounds and metal ions on the antioxidant activity of anthocyanins and the electrochemical properties of anthocyanins are presented. Numerous cases of attenuation of oxidative stress at the cellular and organismal levels by anthocyanins are cited. The direct and indirect antioxidant action of anthocyanins, the question of the specificity of anthocyanin action in complex extracts, as well as limitations of cellular in vitro assays and biomarkers used for the detection of antioxidant effects of anthocyanins, are critically discussed.

Polyphenols: Chemistry, bioavailability, bioactivity, nutritional aspects and human health benefits: A review

Polyphenols, including phenolics, alkaloids, and terpenes, are secondary metabolites that are commonly found in fruits, vegetables, and beverages, such as tea, coffee, wine, chocolate, and beer. These compounds have gained considerable attention and market demand because of their potential health benefits. However, their application is limited due to their low absorption rates and reduced tissue distribution efficiency. Engineering polyphenol-protein complexes or conjugates can enhance the antioxidant properties, bioavailability, and stability of polyphenols and improve digestive enzyme hydrolysis, target-specific delivery, and overall biological functions. Complex polyphenols, such as melanin, tannins, and ellagitannins, can promote gut microbiota balance, bolster antioxidant defense, and improve overall human health. Despite these benefits, the safety of polyphenol complexes must be thoroughly evaluated before their use as functional food additives or supplements. This review provides a detailed overview of the types of macromolecular polyphenols, their chemical composition, and their role in food enrichment. The mechanisms by which complex polyphenols act as antioxidative, anti-inflammatory, and anticancer agents have also been discussed.

Glucoraphanin and sulforaphane mitigate TNFα-induced Caco-2 monolayers permeabilization and inflammation

Intestinal permeabilization is central to the pathophysiology of chronic gut inflammation. This study investigated the efficacy of glucoraphanin (GR), prevalent in cruciferous vegetables, particularly broccoli, and its derivative sulforaphane (SF), in inhibiting tumor necrosis factor alpha (TNFα)-induced Caco-2 cell monolayers inflammation and permeabilization through the regulation of redox-sensitive events. TNFα binding to its receptor led to a rapid increase in oxidant production and subsequent elevation in the mRNA levels of NOX1, NOX4, and Duox2. GR and SF dose-dependently mitigated both these short- and long-term alterations in redox homeostasis. Downstream, GR and SF inhibited the activation of the redox-sensitive signaling cascades NF-κB (p65 and IKK) and MAPK ERK1/2, which contribute to inflammation and barrier permeabilization. GR (1 μM) and SF (0.5-1 μM) prevented TNFα-induced monolayer permeabilization and the associated reduction in the levels of the tight junction (TJ) proteins occludin and ZO-1. Both GR and SF also mitigated TNFα-induced increased mRNA levels of the myosin light chain kinase, which promotes TJ opening. Molecular docking suggests that although GR is mostly not absorbed, it could interact with extracellular and membrane sites in NOX1. Inhibition of NOX1 activity by GR would mitigate TNFα receptor downstream signaling and associated events. These findings support the concept that not only SF, but also GR, could exert systemic health benefits by protecting the intestinal barrier against inflammation-induced permeabilization, in part by regulating redox-sensitive pathways. GR has heretofore not been viewed as a biologically active molecule, but rather, the benign precursor of highly active SF. The consumption of GR and/or SF-rich vegetables or supplements in the diet may offer a means to mitigate the detrimental consequences of intestinal permeabilization, not only in disease states but also in conditions characterized by chronic inflammation of dietary and lifestyle origin.

A flavonoid-rich extract of bergamot juice improves high-fat diet-induced intestinal permeability and associated hepatic damage in mice

Consumption of high-fat diets (HFDs) is a contributing factor to obesity, insulin resistance and non-alcoholic fatty liver disease (NAFLD). Several studies suggested the protective role of bioactives present in Citrus fruits against the above mentioned chronic metabolic conditions. In this study, we evaluated if a flavonoid-rich extract of Citrus bergamia (bergamot) juice (BJe) could inhibit HFD-induced intestinal permeability and endotoxemia and, through this mechanism, mitigate the associated hepatic damage in C57BL/6J mice. After 12 weeks of the treatment, HFD consumption caused high body weight (BW) gain, hyperinsulinemia, hyperglycemia, and dyslipidemia, which were mitigated by BJe (50 mg per kg BW) supplementation. Furthermore, supplementation with BJe prevented HFD-induced liver alterations, including increased plasma alanine aminotransferase (ALT) activity, increased hepatic lipid deposition, high NAS, and fibrosis. Mice fed a HFD for 12 weeks showed (i) a decrease in small intestine tight junction protein levels (ZO-1, occludin, and claudin-1), (ii) increased intestinal permeability, and (iii) endotoxemia. All these adverse events were mitigated by BJe supplementation. Linking the capacity of BJe to prevent HFD-associated endotoxemia, supplementation with this extract decreased the HFD-induced overexpression of hepatic TLR-4, downstream signaling pathways (MyD88, NF-κB and MAPK), and the associated inflammation, evidenced by increased MCP-1, TNF-α, IL-6, iNOS, and F4/80 levels. Overall, we suggest that BJe could mitigate the harmful consequences of western style diet consumption on liver physiology by protecting the gastrointestinal tract from permeabilization and associated metabolic endotoxemia.

Structure-dependent capacity of procyanidin dimers to inhibit inflammation-induced barrier dysfunction in a cell model of intestinal epithelium

Diet is of major importance in modulating intestinal inflammation, as the gastrointestinal tract is directly exposed to high concentrations of dietary components. Procyanidins are flavan-3-ol oligomers abundant in fruits and vegetables. Although with limited or no intestinal absorption, they can have GI health benefits which can promote overall health. We previously observed that epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) dimers inhibit in vitro colorectal cancer cell proliferation and invasiveness. Inflammation-mediated intestinal barrier permeabilization can result in a chronic inflammatory condition and promote colorectal cancer onset/progression. Thus, this study investigated the structure-dependent capacity of ECG, EGCG and (-)-epicatechin (EC) dimers to inhibit tumor necrosis factor alpha (TNFα)-induced inflammation, oxidative stress, and loss of barrier integrity in Caco-2 cells differentiated into an intestinal epithelial cell monolayer. Cells were incubated with TNFα (10 ng/ml), in the absence/presence of ECG, EGCG and EC dimers. The three dimers inhibited TNFα-mediated Caco-2 cell monolayer permeabilization, modulating events involved in the loss of barrier function and inflammation, i.e. decreased tight junction protein levels; increased matrix metalloproteinases expression and activity; increased NADPH oxidase expression and oxidant production; activation of the NF-κB and ERK1/2 pathways and downstream events leading to tight junction opening. For some of these mechanisms, the galloylated ECG and EGCG dimers had stronger protective potency than the non-galloylated EC dimer. These differences could be due to differential membrane interactions as pointed out by molecular dynamics simulation of procyanidin dimers-cell membrane interactions and/or by differential interactions with NOX1. Results show that dimeric procyanidins, although poorly absorbed, can promote health by alleviating intestinal inflammation, oxidative stress and barrier permeabilization.

Dietary Anthocyanins Mitigate High-Fat Diet-Induced Hippocampal Inflammation in Mice

BACKGROUND

Obesity and consumption of high-fat diets (HFD) are associated with intestinal permeabilization and increased paracellular transport of endotoxins, which can promote neuroinflammation. Inflammation can affect the hypothalamic pituitary adrenal (HPA) axis, which controls responses to stress and downregulates the brain-derived neurotrophic factor (BDNF), which can promote anxiety and depression, conditions frequently found in obesity. We previously showed that consumption of anthocyanins (AC) mitigate HFD-induced insulin resistance, intestinal permeability, and inflammation.

OBJECTIVES

This study investigated if a dietary supplementation with a cyanidin- and delphinidin-rich extract (CDRE) could counteract HFD/obesity-induced hippocampal inflammation in mice.

METHODS

C57BL/6J male mice were fed for 14 wk on one of the following diets: 1) a control diet containing 10% total calories from fat (C), 2) a control diet supplemented with 40 mg AC/kg body weight (BW) (CAC), 3) a HFD containing 60% total calories from fat (lard) (HF), or 4) the HFD supplemented with 2, 20, or 40 mg AC/kg BW (HFA2, HFA20, and HFA40, respectively). In plasma and in the hippocampus, parameters of neuroinflammation and the underlying cause (endotoxemia) and consequences (alterations to the HPA and BDNF downregulation) were measured.

RESULTS

Consumption of the HFD caused endotoxemia. Accordingly, hippocampal Tlr4 mRNA levels were 110% higher in the HF group, which were both prevented by CDRE supplementation. Consumption of the HFD also caused: 1) microgliosis and increased expression of genes involved in neuroinflammation, that is, Iba-1, Nox4, Tnfα, and Il-1β, 2) alterations of HPA axis regulation, that is, with low expression of mineralocorticoid (MR) and glucocorticoid (GR) receptors; and 3) decreased Bdnf expression. Supplementation of HFD-fed mice with CDRE mitigated neuroinflammation, microgliosis, and MR and BDNF decreases.

CONCLUSIONS

CDRE supplementation mitigates the negative effects associated with HFD consumption and obesity in mouse hippocampus, in part by decreasing inflammation, improving glucocorticoid metabolism, and upregulating BDNF.

B3galt5 functions as a PXR target gene and regulates obesity and insulin resistance by maintaining intestinal integrity

Pregnane X receptor (PXR) has been reported to regulate glycolipid metabolism. The dysfunction of intestinal barrier contributes to metabolic disorders. However, the role of intestinal PXR in metabolic diseases remains largely unknown. Here, we show that activation of PXR by tributyl citrate (TBC), an intestinal-selective PXR agonist, improves high fat diet (HFD)-induced obesity. The metabolic benefit of intestinal PXR activation is associated with upregulation of β-1,3 galactosyltransferase 5 (B3galt5). Our results reveal that B3galt5 mainly expresses in the intestine and is a direct PXR transcriptional target. B3galt5 knockout exacerbates HFD-induced obesity, insulin resistance and inflammation. Mechanistically, B3galt5 is essential to maintain the integrity of intestinal mucus barrier. B3galt5 ablation impairs the O-glycosylation of mucin2, destabilizes the mucus layer, and increases intestinal permeability. Furthermore, B3galt5 deficiency abolishes the beneficial effect of intestinal PXR activation on metabolic disorders. Our results suggest the intestinal-selective PXR activation regulates B3galt5 expression and maintains metabolic homeostasis, making it a potential therapeutic strategy in obesity.

Red raspberry (Rubus idaeus) preserves intestinal barrier integrity and reduces oxidative stress in Caco-2 cells exposed to a proinflammatory stimulus

Growing evidence showed the capacity of (poly)phenols to exert a protective role on intestinal health. Nevertheless, the existing findings are still heterogeneous and the underlying mechanisms remain unclear. This study investigated the potential benefits of a red raspberry (Rubus idaeus) powder on the integrity of the intestinal barrier, focusing on its ability to mitigate the effects of tumor necrosis factor-α (TNF-α)-induced intestinal permeability. Human colorectal adenocarcinoma cells (i.e., Caco-2 cells) were used as a model to assess the impact of red raspberry on intestinal permeability, tight junction expression, and oxidative stress. The Caco-2 cells were differentiated into polarized monolayers and treated with interferon-γ (IFN-γ) (10 ng mL-1) for 24 hours, followed by exposure to TNF-α (10 ng mL-1) in the presence or absence of red raspberry extract (1-5 mg mL-1). The integrity of the intestinal monolayer was evaluated using transepithelial electrical resistance (TEER) and fluorescein isothiocyanate-dextran (FITC-D) efflux assay. Markers of intestinal permeability (claudin-1, occludin, and zonula occludens-1 (ZO-1)) and oxidative stress (8-hydroxy-2-deoxyguanosine (8-OHdG) and protein carbonyl) were assessed using ELISA kits. Treatment with red raspberry resulted in a significant counteraction of TEER value loss (41%; p < 0.01) and a notable reduction in the efflux of FITC-D (-2.5 times; p < 0.01). Additionally, red raspberry attenuated the levels of 8-OHdG (-48.8%; p < 0.01), mitigating the detrimental effects induced by TNF-α. Moreover, red raspberry positively influenced the expression of the integral membrane protein claudin-1 (+18%; p < 0.01), an essential component of tight junctions. These findings contribute to the growing understanding of the beneficial effects of red raspberry in the context of the intestinal barrier. The effect of red raspberry against TNF-α-induced intestinal permeability observed in our in vitro model suggests, for the first time, its potential as a dietary strategy to promote gastrointestinal health.

An overview on the cellular mechanisms of anthocyanins in maintaining intestinal integrity and function

Structural and functional changes of the intestinal barrier, as a consequence of a number of (epi)genetic and environmental causes, have a main role in penetrations of pathogens and toxic agents, and lead to the development of inflammation-related pathological conditions, not only at the level of the GI tract but also in other extra-digestive tissues and organs. Anthocyanins (ACNs), a subclass of polyphenols belonging to the flavonoid group, are well known for their health-promoting properties and are widely distributed in the human diet. There is large evidence about the correlation between the human intake of ACN-rich products and a reduction of intestinal inflammation and dysfunction. Our review describes the more recent advances in the knowledge of cellular and molecular mechanisms through which ACNs can modulate the main mechanisms involved in intestinal dysfunction and inflammation, in particular the inhibition of the NF-κB, JNK, MAPK, STAT3, and TLR4 proinflammatory pathways, the upregulation of the Nrf2 transcription factor and the expression of tight junction proteins and mucins.

Therapeutic Effects of Plant Anthocyanin against Alzheimer's Disease and Modulate Gut Health, Short-Chain Fatty Acids

Alzheimer's disease (AD) is the most common form of dementia and neurogenerative disease (NDD), and it is also one of the leading causes of death worldwide. The number of AD patients is over 55 million according to 2020 Alzheimer's Disease International (ADI), and the number is increasing drastically without any effective cure. In this review, we discuss and analyze the potential role of anthocyanins (ACNs) against AD while understanding the molecular mechanisms. ACNs have been reported as having neuroprotective effects by mitigating cognitive impairments, apoptotic markers, neuroinflammation, aberrant amyloidogenesis, and tauopathy. Taken together, ACNs could be an important therapeutic agent for combating or delaying the onset of AD.

Physiologic effects of the maqui berry (Aristotelia chilensis): a focus on metabolic homeostasis

The prevalence and socioeconomic impact of metabolic diseases is rapidly growing. The limited availability of effective and affordable treatments has fuelled interest in the therapeutic potential of natural compounds as they occur in selected food sources. These compounds might help to better manage the current problems of treatment availability, affordability, and adverse effects that, in combination, limit treatment duration and efficacy at present. Specifically, berries garnered interest given a strong epidemiological link between their consumption and improved metabolic functions, making the analysis of their phytochemical composition and the identification and characterization of biologically active ingredients an emerging area of research. In this regard, the present review focuses on the South American maqui berry Aristotelia chilensis, which has been extensively used by the indigenous Mapuche population for generations to treat a variety of disease conditions. An overview of the maqui plant composition precedes a review of pre-clinical and clinical studies that investigated the effects of maqui berries and their major components on metabolic homeostasis. The final part of the review highlights possible technologies to conserve maqui berry structural and functional integrity during passage through the small intestine, ultimately aiming to augment their systemic and luminal bioavailability and biological effects. The integration of the various aspects discussed herein can assist in the development of effective maqui-based therapies to benefit the growing population of metabolically compromised patients.

High-fat diet impairs gut barrier through intestinal microbiota-derived reactive oxygen species

Gut barrier disruption is a key event in bridging gut microbiota dysbiosis and high-fat diet (HFD)-associated metabolic disorders. However, the underlying mechanism remains elusive. In the present study, by comparing HFD- and normal diet (ND)-treated mice, we found that the HFD instantly altered the composition of the gut microbiota and subsequently damaged the integrity of the gut barrier. Metagenomic sequencing revealed that the HFD upregulates gut microbial functions related to redox reactions, as confirmed by the increased reactive oxygen species (ROS) levels in fecal microbiota incubation in vitro and in the lumen, which were detected using in vivo fluorescence imaging. This microbial ROS-producing capability induced by HFD can be transferred through fecal microbiota transplantation (FMT) into germ-free (GF) mice, downregulating the gut barrier tight junctions. Similarly, mono-colonizing GF mice with an Enterococcus strain excelled in ROS production, damaged the gut barrier, induced mitochondrial malfunction and apoptosis of the intestinal epithelial cells, and exacerbated fatty liver, compared with other low-ROS-producing Enterococcus strains. Oral administration of recombinant high-stability-superoxide dismutase (SOD) significantly reduced intestinal ROS, protected the gut barrier, and improved fatty liver against the HFD. In conclusion, our study suggests that extracellular ROS derived from gut microbiota play a pivotal role in HFD-induced gut barrier disruption and is a potential therapeutic target for HFD-associated metabolic diseases.

Anthocyanins and their metabolites promote white adipose tissue beiging by regulating mitochondria thermogenesis and dynamics

High-fat diet (HFD) consumption and excess nutrient availability can cause alterations in mitochondrial function and dynamics. We previously showed that anthocyanins (AC) decreased HFD-induced body weight gain and fat deposition. This study investigated: i) the capacity of AC to mitigate HFD-induced alterations in mitochondrial dynamics, biogenesis, and thermogenesis in mouse subcutaneous white adipose tissue (sWAT), and ii) the underlying mechanisms of action of cyanidin-3-O-glucoside (C3G), delphinidin-3-O-glucoside (D3G), and their gut metabolites on mitochondria function/dynamics in 3T3-L1 adipocytes treated with palmitate. Mice were fed control or HFD diets, added or not with 40 mg AC/kg body weight (BW). Compared to control and AC-supplemented mice, HFD-fed mice had fewer sWAT mitochondria that presented alterations of their architecture. AC supplementation prevented HFD-induced decrease of proteins involved in mitochondria biogenesis (PPARγ, PRDM16 and PGC-1α), and thermogenesis (UCP-1), and decreased AMPK phosphorylation. AC supplementation also restored the alterations in sWAT mitochondrial dynamics (Drp-1, OPA1, MNF-2, and Fis-1) and mitophagy (BNIP3L/NIX) caused by HFD consumption. In mature 3T3-L1, C3G, D3G, and their metabolites protocatechuic acid (PCA), 4-hydroxybenzaldehyde (HB), and gallic acid (GA) differentially affected palmitate-mediated decreased cAMP, PKA, AMPK, and SIRT-1 signaling pathways. C3G, D3G, and metabolites also prevented palmitate-mediated decreased expression of PPARγ, PRDM16, PGC-1α, and UCP1. Results suggest that consumption of select AC, i.e. cyanidin and delphinidin, could promote sWAT mitochondriogenesis and improve mitochondria dynamics in the context of HFD/obesity-induced dysmetabolism in part by regulating PKA, AMPK, and SIRT-1 signaling pathways.

Obesogenic polystyrene microplastic exposures disrupt the gut-liver-adipose axis

Microplastics (MP) derived from the weathering of polymers, or synthesized in this size range, have become widespread environmental contaminants and have found their way into water supplies and the food chain. Despite this awareness, little is known about the health consequences of MP ingestion. We have previously shown that the consumption of polystyrene (PS) beads was associated with intestinal dysbiosis and diabetes and obesity in mice. To further evaluate the systemic metabolic effects of PS on the gut-liver-adipose tissue axis, we supplied C57BL/6J mice with normal water or that containing 2 sizes of PS beads (0.5 and 5 µm) at a concentration of 1 µg/ml. After 13 weeks, we evaluated indices of metabolism and liver function. As observed previously, mice drinking the PS-containing water had a potentiated weight gain and adipose expansion. Here we found that this was associated with an increased abundance of adipose F4/80+ macrophages. These exposures did not cause nonalcoholic fatty liver disease but were associated with decreased liver:body weight ratios and an enrichment in hepatic farnesoid X receptor and liver X receptor signaling. PS also increased hepatic cholesterol and altered both hepatic and cecal bile acids. Mice consuming PS beads and treated with the berry anthocyanin, delphinidin, demonstrated an attenuated weight gain compared with those mice receiving a control intervention and also exhibited a downregulation of cyclic adenosine monophosphate (cAMP) and peroxisome proliferator-activated receptor (PPAR) signaling pathways. This study highlights the obesogenic role of PS in perturbing the gut-liver-adipose axis and altering nuclear receptor signaling and intermediary metabolism. Dietary interventions may limit the adverse metabolic effects of PS consumption.

Interindividual differences in aronia juice tolerability linked to gut microbiome and metabolome changes-secondary analysis of a randomized placebo-controlled parallel intervention trial

BACKGROUND

Aronia melanocarpa is a berry rich in polyphenols known for health benefits. However, the bioavailability of polyphenols has been questioned, and the individual taste acceptance of the fruit with its specific flavor varies. We recently observed substantial differences in the tolerability of aronia juice among healthy females, with half of the individuals tolerating aronia juice without complaints. Given the importance of the gut microbiome in food digestion, we investigated in this secondary analysis of the randomized placebo-controlled parallel intervention study (ClinicalTrials.gov registration: NCT05432362) if aronia juice tolerability was associated with changes in intestinal microbiota and bacterial metabolites, seeking for potential mechanistic insights into the impact on aronia polyphenol tolerance and metabolic outcomes.

RESULTS

Forty females were enrolled for this 6-week trial, receiving either 100 ml natural aronia juice (verum, V) twice daily or a polyphenol-free placebo (P) with a similar nutritional profile, followed by a 6-week washout. Within V, individuals were categorized into those who tolerated the juice well (Vt) or reported complaints (Vc). The gut microbiome diversity, as analyzed by 16S rRNA gene-based next-generation sequencing, remained unaltered in Vc but changed significantly in Vt. A MICOM-based flux balance analysis revealed pronounced differences in the 40 most predictive metabolites post-intervention. In Vc carbon-dioxide, ammonium and nine O-glycans were predicted due to a shift in microbial composition, while in Vt six bile acids were the most likely microbiota-derived metabolites. NMR metabolomics of plasma confirmed increased lipoprotein subclasses (LDL, VLDL) post-intervention, reverting after wash out. Stool samples maintained a stable metabolic profile.

CONCLUSION

In linking aronia polyphenol tolerance to gut microbiota-derived metabolites, our study explores adaptive processes affecting lipoprotein profiles during high polyphenol ingestion in Vt and examines effects on mucosal gut health in response to intolerance to high polyphenol intake in Vc. Our results underpin the importance of individualized hormetic dosing for beneficial polyphenol effects, demonstrate dynamic gut microbiome responses to aronia juice, and emphasize personalized responses in polyphenol interventions.

Xihuang pill ameliorates colitis in mice by improving mucosal barrier injury and inhibiting inflammatory cell filtration through network regulation

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of colitis is on the rise, and effective treatment options are currently lacking. Xihuang pill (XHP) is a traditional Chinese medicine formula mentioned in the "Volume 4 of Surgical Evidence and Treatment of the Whole Life" authored by the renowned doctor Hong-Xu Wang during the Qing Dynasty. It is now part of the "Volume 9 of Chinese medicine formula preparation in Drug Standard." XHP and its primary ingredients have been demonstrated anti-inflammatory properties against colitis. However, the specific effects and underlying mechanisms of XHP in treating colitis remain unknown.

AIM OF THE STUDY

This study aimed to investigate the potential impact of XHP on colitis and uncover the underlying mechanisms involved.

MATERIALS AND METHODS

An acute colitis model was developed in C57BL/6N mice, and the effects on weight loss, colon length, the permeability of the colonic mucosa barrier, Claudin-5 and Occludin expression, number of both infiltrating MPO-positive cells and CD68-positive cells, and the content of pro-inflammatory cytokines (IL-6, IL-22, IL-1β, and TNF-α) in the colon tissue were investigated. Low-, medium-, and high-dose XHP (0.45, 0.9, and 1.8 g/kg/day) (batch number: z21021222) were administered to the mice by gavage over the course of two weeks. Additionally, the protein expression levels in colon tissue from the control group, colitis group, and XHP low-dose administration group mice were analyzed by quantitative proteomics techniques. The comprehensive profiling and characterization of absorbed components in mice blood following oral administration of XHP were identified by HPLC/Q-TOF-MS techniques, and the absorbed components in blood were combined with proteomics to reveal the mechanism of enteritis inhibition by XHP.

RESULTS

Our findings indicated that XHP enhanced weight loss and colonic shortening of colitis mice. Additionally, XHP reduced the increase in permeability of the colonic mucosa barrier and decreased expression of Claudin-5 and Occludin, while significantly reducing the number of infiltrating MPO-positive cells and CD68-positive cells in the colon tissue. We found that XHP reduced the production of pro-inflammatory cytokines, including IL-6, IL-22, IL-1β, and TNF-α in colon tissue. Pharmacokinetic analysis suggested that XHP contained 24 blood-entering prototype ingredients, which improved colitis through the regulation of various proteins (e.g., Ctsb, Sting1, and Abat) linked to mucosal barrier injury and inflammation.

CONCLUSION

XHP improved intestinal mucosal barrier injury and reduced MPO-positive cells and CD68-positive cell infiltration through multiple targets and pathways, providing support for XHP as a promising therapy for colitis.

The Potential Role of Intestinal Stem Cells and Microbiota for the Treatment of Colorectal Cancer

Colorectal cancer is a global health concern with high incidence and mortality rates. Conventional treatments like surgery, chemotherapy, and radiation therapy have limitations in improving patient survival rates. Recent research highlights the role of gut microbiota and intestinal stem cells in maintaining intestinal health and their potential therapeutic applications in colorectal cancer treatment. The interaction between gut microbiota and stem cells influences epithelial self-renewal and overall intestinal homeostasis. Novel therapeutic approaches, including immunotherapy, targeted therapy, regenerative medicine using stem cells, and modulation of gut microbiota, are being explored to improve treatment outcomes. Accordingly, this chapter provides an overview of the potential therapeutic applications of gut microbiota and intestinal stem cells in treating colorectal cancer.

Deficiency of S100A8/A9 attenuates pulmonary microvascular leakage in septic mice

BACKGROUND

We have reported a positive correlation between S100 calcium-binding protein (S100) A8/S100A9 and sepsis-induced lung damage before. However, limited knowledge exists concerning the biological role of S100A8/A9 in pulmonary vascular endothelial barrier dysfunction, as well as the diagnostic value of S100A8/A9 in sepsis.

METHODS

Sepsis was induced in C57BL/6J mice and S100A9-knockout (KO) mice through the cecal ligation and puncture (CLP). Pulmonary vascular leakage was determined by measuring extravasated Evans blue (EB). Reverse transcription polymerase chain reaction and the histological score were used to evaluate inflammation and lung injury, respectively. Recombinant S100A8/A9 (rhS100A8/A9) was used to identify the effects of S100A8/A9 on endothelial barrier dysfunction in human umbilical vein endothelial cells (HUVECs). Additionally, the diagnostic value of S100A8/A9 in sepsis was assessed using receiver operating characteristic.

RESULTS

S100A8/A9 expression was up-regulated in the lungs of CLP-operated mice. S100A9 KO significantly reversed CLP-induced hypothermia and hypotension, resulting in an improved survival rate. S100A9 KO also decreased the inflammatory response, EB leakage, and histological scores in the lungs of CLP-operated mice. Occludin and VE-cadherin expressions were decreased in the lungs of CLP-operated mice; However, S100A9 KO attenuated this decrease. Moreover, CLP-induced signal transducer and activator of transcription 3 (STAT3) and p38/extracellular signal-regulated kinase (ERK) signalling activation and apoptosis were mitigated by S100A9 KO in lungs. In addition, rhS100A8/A9 administration significantly decreased occludin and VE-cadherin expressions, increased the phosphorylated (p)-ERK/ERK, p-p38/p38, and B-cell leukaemia/lymphoma 2 protein (Bcl-2)-associated X protein/Bcl-2 ratios in HUVECs.

CONCLUSION

The present study demonstrated S100A8/A9 aggravated sepsis-induced pulmonary inflammation, vascular permeability, and lung injury. This was achieved, at least partially, by activating the P38/STAT3/ERK signalling pathways. Moreover, S100A8/A9 showed the potential as a biomarker for sepsis diagnosis.

(Poly)phenols and the regulation of NADPH oxidases

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are enzymes that generate superoxide anion (O2•-) and hydrogen peroxide (H2O2), and that are widely distributed in mammalian tissues. Many bioactives, especially plant (poly)phenols are being studied for their capacity to regulate NOXs. The modulation of these enzymes are of central relevance to maintain redox homeostasis and regulate cell signaling. In in vitro and ex vivo assays, and in experimental animal models, different (poly)phenols are able to modulate NOX-dependent generation of O2•- and H2O2. Mechanistically, most of the known effects of (poly)phenols and of their metabolites on NOX1, NOX2, and NOX4, include the modulation of: i) the expression of the different constituent subunits, and/or ii) posttranslational modifications involved in the assembly and translocation of the protein complexes. Very limited evidence is available on a direct action of (poly)phenols on NOX active site (electron-transferring protein). Moreover, it is suggested that the regulation by (poly)phenols of systemic events, e.g. inflammation, is frequently associated with their capacity to regulate NOX activation. Although of physiological significance, more studies are needed to understand the specific targets/mechanisms of NOX regulation by (poly)phenols, and the (poly)phenol chemical structures and moieties directly involved in the observed effects. It should be kept in mind the difficulties of NOX's studies associated with the complexity of NOXs biochemistry and the methodological limitations of O2•- and H2O2 the determinations. Studies relating human ingestion of specific (poly)phenols, with NOX activity and disease conditions, are guaranteed to better understand the health importance of (poly)phenol consumption and the involvement of NOXs as biological targets.

Chlorogenic Acid Ameliorates Post-Infectious Irritable Bowel Syndrome by Regulating Extracellular Vesicles of Gut Microbes

Post-infectious irritable bowel syndrome (PI-IBS) occurs after acute infectious diarrhea, and dysbiosis can be involved in its pathogenesis. Here, the role of chlorogenic acid (CGA) is investigated, a natural compound with several pharmacological properties, in alleviating PI-IBS in rats. It is elucidated that the gut microbiota plays a key role in PI-IBS pathogenesis and that rectal administration of CGA alleviated PI-IBS by modulating the gut microbiota and its metabolites. CGA supplementation significantly increased fecal Bacteroides acidifaciens abundance and glycine levels. Glycine structurally altered B. acidifaciens extracellular vesicles (EVs) and enriched functional proteins in the EVs; glycine-induced EVs alleviated PI-IBS by reducing inflammation and hypersensitivity of the intestinal viscera and maintaining mucosal barrier function. Moreover, B. acidifaciens EVs are enriched in the brain tissue. Thus, CGA mediates the mitigation of PI-IBS through the gut microbiota and its metabolites. This study proposes a novel mechanism of signal exchange between the gut microenvironment and the host.

The role of NADPH oxidase 1 in alcohol-induced oxidative stress injury of intestinal epithelial cells

Alcohol-mediated reactive oxygen species (ROS) play a vital role in intestinal barrier injury. However, the mechanism of ROS accumulation in enterocytes needs to be explored further. In our study, we found that chronic-binge ethanol-fed mice had increased levels of gut oxidative stress and high intestinal permeability. The transcription profiles of the colonic epithelial cells showed that the level of NADPH oxidase 1 (NOX1) was significantly elevated in alcohol-exposed mice compared with isocaloric-exposed mice. In vitro, NOX1 silencing alleviated ROS accumulation and the apoptosis of human colonic epithelial cells (NCM460), while NOX1 overexpression accelerated oxidative stress injury of NCM460 cells. Propionic acid was reduced in the gut of chronic-binge ethanol-fed mice, compared with isocaloric-fed mice, as observed through untargeted metabolomic analysis. Supplementation with propionate relieved ethanol-induced liver and intestinal barrier injuries and reduced the level of ROS accumulation and apoptosis of ethanol-induced colonic epithelial cells. Propionate alleviating NOX1 induced ROS injury of colonic epithelial cells, independent of G protein-coupled receptors. Propionate significantly inhibited histone deacetylase 2 (HDAC2) expressions both in ethanol-exposed colonic epithelial cells and TNF-α-treated NCM460. Chromatin immunoprecipitation (ChIP) assays showed that propionate suppressed the NOX1 expression by regulating histone acetylation in the gene promoter region. In conclusion, NOX1 induces oxidative stress injury of colonic epithelial cells in alcohol-related liver disease. Propionate, which can act as an endogenous HDAC2 inhibitor, can decrease levels of apoptosis of intestinal epithelial cells caused by oxidative stress.

Anthocyanins as Immunomodulatory Dietary Supplements: A Nutraceutical Perspective and Micro-/Nano-Strategies for Enhanced Bioavailability

Anthocyanins (ACNs) have attracted considerable attention for their potential to modulate the immune system. Research has revealed their antioxidant and anti-inflammatory properties, which play a crucial role in immune regulation by influencing key immune cells, such as lymphocytes, macrophages, and dendritic cells. Moreover, ACNs contribute towards maintaining a balance between proinflammatory and anti-inflammatory cytokines, thus promoting immune health. Beyond their direct effects on immune cells, ACNs significantly impact gut health and the microbiota, essential factors in immune regulation. Emerging evidence suggests that they positively influence the composition of the gut microbiome, enhancing their immunomodulatory effects. Furthermore, these compounds synergize with other bioactive substances, such as vitamins and minerals, further enhancing their potential as immune-supporting dietary supplements. However, detailed clinical studies must fully validate these findings and determine safe dosages across varied populations. Incorporating these natural compounds into functional foods or supplements could revolutionize the management of immune-related conditions. Personalized nutrition and healthcare strategies may be developed to enhance overall well-being and immune resilience by fully understanding the mechanisms underlying the actions of their components. Recent advancements in delivery methods have focused on improving the bioavailability and effectiveness of ACNs, providing promising avenues for future applications.

Polyphenolic profiles of a variety of wild berries from the Pacific Northwest region of North America

Polyphenols have been extensively profiled and quantified in commercially grown berries, but similar information is sparsely available for wild berries. Because polyphenolic contents are inherently associated with berries health benefits, determining phenolic profiles is an important step for strategizing potential uses by the industry and for health and nutrition outcomes. Here, we profiled phenolic compounds in wild berries commonly encountered and harvested in the Pacific Northwest region of North America. Huckleberries (Vaccinium membranaceum) of varying phenotypes were found to be comparable to related blueberries in terms of general phenolic classes composition. However, all huckleberries exhibited markedly high levels of cyanidins, and delphinidins or peonidins were also higher in specific phenotypes. Wild black elderberries (Sambucus nigra spp. Canadensis) were found to have remarkably high phenolic, especially anthocyanins, in line with reports from cultivated elderberries. Saskatoon serviceberries (Amelanchier alnifolia) were found to exhibit high polyphenol content, but with a less diverse profile dominated by quercetin. The most intriguing berry may be the Oregon grape (Mahonia Aquifolium) being the only one exhibiting more than one g of polyphenols per 100 g; as well as a remarkably even distribution of the different anthocyanin classes. All colored wild berries were found to have at minimum comparable total phenolic contents when compared to cultivated and other wild berries, suggesting they should exhibit comparable human health benefits such as antioxidant and metabolic syndrome preventative potential described for these other berries. Overall, our data represents a valuable resource to explore the potential to valorize wild berry species for their specific phenolic profiles and predicted nutritional and health properties. With repeated phenolic profiling to better understand the impact of the environment, the wild berries described here hold promises both as food ingredient applications as well as valuable complement for healthy dietary patterns.

Wild blueberry (V. angustifolium) improves TNFα-induced cell barrier permeability through claudin-1 and oxidative stress modulation in Caco-2 cells

Increasing evidence links the impairment of intestinal permeability (IP), a feature of the intestinal barrier, to numerous dysmetabolic and dysfunctional conditions. Several host and environmental factors, including dietary factors, can negatively and/or positively affect IP. In this regard, polyphenol-rich foods including berries have been proposed as potential IP modulators. However, the exact mechanisms involved are not yet fully elucidated. The aim of the present study was to evaluate the effect of a wild blueberry (WB; V. angustifolium) powder, naturally rich in polyphenols, to affect Caco-2 cell monolayer permeability and to identify the potential mechanisms in modulating the IP process. Caco-2 cells were incubated with TNF-α (10 ng mL-1), as a pro-inflammatory stimulus, and supplemented for 24 hours with different concentrations (1 and 5 mg mL-1) of WB powder. The integrity of the intestinal cell monolayer was evaluated by measuring the transepithelial electrical resistance (TEER) and the paracellular transport of FITC-dextran. In addition, the production of the tight junction proteins, such as claudin-1 and occludin, as well as protein carbonyl and 8-hydroxy 2 deoxyguanosine, as oxidative stress markers, were quantified in the supernatant by ELISA kits. Overall, the treatment with WB powder (5 mg mL-1) mitigated the loss of Caco-2 cell barrier integrity, as documented by an increase in TEER and a reduction in FITC values. This modulation was accompanied by an upregulation of claudin-1 and a reduction of 8-OHdG. Conversely, no effect was documented for the lower concentration (1 mg mL-1) and the other IP markers, as well as oxidative stress markers analysed. In conclusion, our findings suggest a potential role of WB in the modulation of cell barrier integrity. This modulation process could be attributed to an increase in claudin-1 expression and a reduction in 8-OHdG. Further studies should be performed to corroborate the results obtained. In addition, since the effects were observed at doses of WB achievable with the diet, these findings should be substantiated also through in vivo approaches.

In vitro models as a tool to study the role of gut microbiota in obesity

Obesity, a highly prevalent condition worldwide that leads to the development of multiple metabolic diseases, has been related to gut microbial dysbiosis. To understand this correlation, in vivo models have been extremely useful. However, its use is limited by associated ethical concerns, high costs, low representativeness, and low reproducibility. Therefore, new and improved in vitro models have been developed in recent years, representing a promising tool in the study of the role of gut microbiota modulation in weight management and metabolic health. This review aims to provide an update on the main findings obtained in vitro regarding gut microbiota modulation with probiotics, and food compounds, and its interaction with the host metabolism, associated with obesity. Available in vitro colon models currently used to study obesity are discussed, including batch and dynamic fermentation systems, and models that allow the study of microbiota-host interactions using cell cultures. In vitro models have demonstrated that homeostatic microbiota may help overcome obesity by producing satiety-related neurotransmitters and metabolites that protect the gut barrier and improve the metabolic activity of adipose tissue. In vitro models may be the key to finding new treatments for obesity-related disorders.

Valorization of polyphenolic compounds from food industry by-products for application in polysaccharide-based nanoparticles

In the last decades, evidence has indicated the beneficial properties of dietary polyphenols. In vitro and in vivo studies support that the regular intake of these compounds may be a strategy to reduce the risks of some chronic non-communicable diseases. Despite their beneficial properties, they are poorly bioavailable compounds. Thus, the main objective of this review is to explore how nanotechnology improves human health while reducing environmental impacts with the sustainable use of vegetable residues, from extraction to the development of functional foods and supplements. This extensive literature review discusses different studies based on the application of nanotechnology to stabilize polyphenolic compounds and maintain their physical-chemical stability. Food industries commonly generate a significant amount of solid waste. Exploring the bioactive compounds of solid waste has been considered a sustainable strategy in line with emerging global sustainability needs. Nanotechnology can be an efficient tool to overcome the challenge of molecular instability, especially using polysaccharides such as pectin as assembling material. Complex polysaccharides are biomaterials that can be extracted from citrus and apple peels (from the juice industries) and constitute promising wall material stabilizing chemically sensitive compounds. Pectin is an excellent biomaterial to form nanostructures, as it has low toxicity, is biocompatible, and is resistant to human enzymes. The potential extraction of polyphenols and polysaccharides from residues and their inclusion in food supplements may be a possible application to reduce environmental impacts and constitutes an approach for effectively including bioactive compounds in the human diet. Extracting polyphenolics from industrial waste and using nanotechnology may be feasible to add value to food by-products, reduce impacts on nature and preserve the properties of these compounds.

Anthocyanins ameliorate obesity-associated metainflammation: Preclinical and clinical evidence

The growing rates of obesity worldwide call for intervention strategies to help control the pathophysiological consequences of weight gain. The use of natural foods and bioactive compounds has been suggested as such a strategy because of their recognized antioxidant and anti-inflammatory properties. For example, polyphenols, especially anthocyanins, are candidates for managing obesity and its related metabolic disorders. Obesity is well known for the presence of metainflammation, which has been labeled as an inflammatory activation that leads to a variety of metabolic disorders, usually related to increased oxidative stress. Considering this, anthocyanins may be promising natural compounds able to modulate several intracellular mechanisms, mitigating oxidative stress and metainflammation. A wide variety of foods and extracts rich in anthocyanins have become the focus of research in the field of obesity. Here, we bring together the current knowledge regarding the use of anthocyanins as an intervention tested in vitro, in vivo, and in clinical trials to modulate metainflammation. Most recent research applies a wide variety of extracts and natural sources of anthocyanins, in diverse experimental models, which represents a limitation of the research field. However, the literature is sufficiently consistent to establish that the in-depth molecular analysis of gut microbiota, insulin signaling, TLR4-triggered inflammation, and oxidative stress pathways reveals their modulation by anthocyanins. These targets are interconnected at the cellular level and interact with one another, leading to obesity-associated metainflammation. Thus, the positive findings with anthocyanins observed in preclinical models might directly relate to the positive outcomes in clinical studies. In summary and based on the entirety of the relevant literature, anthocyanins can mitigate obesity-related perturbations in gut microbiota, insulin resistance, oxidative stress and inflammation and therefore may contribute as a therapeutic tool in people living with obesity.

Blackcurrant Alleviates Dextran Sulfate Sodium (DSS)-Induced Colitis in Mice

Previous studies have reported that anthocyanin (ACN)-rich materials have beneficial effects on ulcerative colitis (UC). Blackcurrant (BC) has been known as one of the foods rich in ACN, while studies demonstrating its effect on UC are rare. This study attempted to investigate the protective effects of whole BC in mice with colitis using dextran sulfate sodium (DSS). Mice were orally given whole BC powder at a dose of 150 mg daily for four weeks, and colitis was induced by drinking 3% DSS for six days. Whole BC relieved symptoms of colitis and pathological changes in the colon. The overproduction of pro-inflammatory cytokines such as IL-1β, TNF-α, and IL-6 in serum and colon tissues was also reduced by whole BC. In addition, whole BC significantly lowered the levels of mRNA and protein of downstream targets in the NF-κB signaling pathway. Furthermore, BC administration increased the expression of genes related to barrier function: ZO-1, occludin, and mucin. Moreover, the whole BC modulated the relative abundance of gut microbiota altered with DSS. Therefore, the whole BC has demonstrated the potential to prevent colitis through attenuation of the inflammatory response and regulation of the gut microbial composition.

Anthocyanin actions at the gastrointestinal tract: Relevance to their health benefits

Anthocyanins (AC) are flavonoids abundant in the human diet, which consumption has been associated to several health benefits, including the mitigation of cardiovascular disease, type 2 diabetes, non-alcoholic fatty liver disease, and neurological disorders. It is widely recognized that the gastrointestinal (GI) tract is not only central for food digestion but actively participates in the regulation of whole body physiology. Given that AC, and their metabolites reach high concentrations in the intestinal lumen after food consumption, their biological actions at the GI tract can in part explain their proposed local and systemic health benefits. In terms of mechanisms of action, AC have been found to: i) inhibit GI luminal enzymes that participate in the absorption of lipids and carbohydrates; ii) preserve intestinal barrier integrity and prevent endotoxemia, inflammation and oxidative stress; iii) sustain goblet cell number, immunological functions, and mucus production; iv) promote a healthy microbiota; v) be metabolized by the microbiota to AC metabolites which will be absorbed and have systemic effects; and vi) modulate the metabolism of GI-generated hormones. This review will summarize and discuss the latest information on AC actions at the GI tract and their relationship to overall health benefits.

Effect of anthocyanins on gut health markers, Firmicutes-Bacteroidetes ratio and short-chain fatty acids: a systematic review via meta-analysis

Researchers discovered that diets rich in anthocyanin-rich fruits and vegetables significantly impacted gut flora. To conclude, large-scale randomized controlled clinical trials are challenging to conduct; therefore, merging data from multiple small studies may aid. A systematic review collects and analyses all research on a particular subject and design. This comprehensive review and meta-analysis examined the influence of dietary anthocyanins on Firmicutes/Bacteroide (Fir/Bac) and short-chain fatty acids (SCFAs) content. The current meta-analysis followed the guidelines of PRISMA-the preferred reporting items for systematic reviews and meta-analyses. Diets high in anthocyanins substantially reduced the Fir/Bac ratio in the assessed trials. Among three SCFAs, the highest impact was observed on acetic acid, followed by propionic acid, and then butanoic acid. The meta-analysis results also obtained sufficient heterogeneity, as indicated by I² values. There is strong evidence that anthocyanin supplementation improves rodent gut health biomarkers (Fir/Bac and SCFAs), reducing obesity-induced gut dysbiosis, as revealed in this systematic review/meta-analysis. Anthocyanin intervention duration and dosage significantly influenced the Fir/Bac ratio and SCFA. Anthocyanin-rich diets were more effective when consumed over an extended period and at a high dosage.

Torularhodin-Loaded Bilosomes Ameliorate Lipid Accumulation and Amino Acid Metabolism in Hypercholesterolemic Mice

SCOPE

Hypercholesterolemia is a cause of cardiovascular disease. Torularhodin is a carotenoid, and its entrapment in bilosomes helps to improve its bioavailability.

METHODS AND RESULTS

The effects of torularhodin-loaded bilosomes on lipid accumulation, inflammatory response, and serum metabolic profiles in hypercholesterolemic ApoE-/- C57BL/6J mice were investigated by feeding a high-fat, high-cholesterol diet (HFHCD) for 20 weeks. At the same time, mice were gavaged with torularhodin-loaded bilosomes for 10 weeks. The results showed that torularhodin successfully alleviated weight gain and insulin resistance in mice and could also lower blood lipids. Meanwhile, torularhodin improved liver lipid accumulation in mice and modulated inflammatory factors in the "blood-liver-ileum." Nontargeted metabolomics revealed that torularhodin significantly increased the concentrations of l-tryptophan, glyceraldehyde, hypotaurine, pyrophosphate, and niacinamide in serum (p < 0.01). In addition, targeted amino acid metabolomics verification found that torularhodin promoted the metabolism of serum amino acids in mice, particularly for branched-chain amino acids, thereby helping to improve hypercholesterolemia in mice. Finally, interaction network bioinformatics was used to demonstrate that amino acid metabolism represented an important mechanism by which torularhodin improves lipid accumulation and inflammatory response in mice.

CONCLUSIONS

Torularhodin can improve hypercholesterolemia in HFHCD-fed mice, thereby supporting the feasibility of its usage in food applications for cardiovascular disease prevention.

Thyme (Thymus vulgaris L.) polyphenols ameliorate DSS-induced ulcerative colitis of mice by mitigating intestinal barrier damage, regulating gut microbiota, and suppressing TLR4/NF-κB-NLRP3 inflammasome pathways

Thyme (Thymus vulgaris L.) is an important medicinal and edible homologous plant, and the composition and bioactivity of its polyphenol extracts have attracted widespread attention from researchers. In this study, the polyphenols in thyme were separated and identified by UPLC/MS-MS and UPLC-DAD, and the intervention effect and mechanism of thyme polyphenols (TP) on ulcerative colitis (UC) were analyzed in combination with dextran sulfate sodium salt (DSS)-induced mice colitis model. It was found that the main substances of TP were scutellarin (160.68 ± 2.09 mg g^-1), rosmarinic acid (80.33 ± 1.74 mg g^-1), scutellarein (56.53 ± 1.32 mg g^-1), apigenin-7-O-glucuronide (21.06 ± 0.68 mg g^-1), gallic acid (13.80 ± 0.73 mg g^-1), and ferulic acid (12.00 ± 0.20 mg g^-1). TP and sulfasalazine, which were respectively supplemented to these experimental mice at 200 mg per kg bw and 100 mg per kg bw, showed similar effects on alleviating intestinal inflammation, as indicated by the consistency of the decreased NLRP3 and TLR4 proteins and inhibited pro-inflammatory cytokine secretion in NF-κB inflammatory signaling pathway. Furthermore, the treatment with TP at doses of 200 and 400 mg per kg bw both effectively upregulated tight junction protein expression and enhanced intestinal epithelial cell integrity. Consistently, the abundany of probiotics including Blautia, Bacteroides, Romboutsia, and Faecalibaculum associated with the synthesis of short chain fatty acids (SCFAs) were elevated, whereas harmful bacteria including Escherichia Shigella, Muribaculum, and Clostridium sensu stricto 1 associated with the inflammatory process were significantly inhibited. Notably, TP supplemented at the dose of 100 mg per kg bw showed weak mitigated effects on the above symptoms, while the other two TP experimental groups showed similar promising therapeutic potential, suggesting that such beneficial effects required a certain dose of TP to be achieved. These results indicated that TP could suppress the TLR4/NLRP3-NF-κB inflammasome pathways, protect the intestinal epithelial barrier, and remodel the disordered gut microbiota, which suggested that TP might be a promising dietary strategy for UC.

A New Frontier in Studying Dietary Phytochemicals in Cancer and in Health: Metabolic and Epigenetic Reprogramming

Metabolic rewiring and epigenetic reprogramming are closely inter-related, and mutually regulate each other to control cell growth in cancer initiation, promotion, progression, and metastasis. Epigenetics plays a crucial role in regulating normal cellular functions as well as pathological conditions in many diseases, including cancer. Conversely, certain mitochondrial metabolites are considered as essential cofactors and regulators of epigenetic mechanisms. Furthermore, dysregulation of metabolism promotes tumor cell growth and reprograms the cells to produce metabolites and bioenergy needed to support cancer cell proliferation. Hence, metabolic reprogramming which alters the metabolites/epigenetic cofactors, would drive the epigenetic landscape, including DNA methylation and histone modification, that could lead to cancer initiation, promotion, and progression. Recognizing the diverse array of benefits of phytochemicals, they are gaining increasing interest in cancer interception and treatment. One of the significant mechanisms of cancer interception and treatment by phytochemicals is reprogramming of the key metabolic pathways and remodeling of cancer epigenetics. This review focuses on the metabolic remodeling and epigenetics reprogramming in cancer and investigates the potential mechanisms by which phytochemicals can mitigate cancer.

Si-Wu Water Extracts Protect against Colonic Mucus Barrier Damage by Regulating Muc2 Mucin Expression in Mice Fed a High-Fat Diet

A high-fat diet (HFD) could cause gut barrier damage. The herbs in si-wu (SW) include dang gui (Angelica sinensis (Oliv.) Diels), shu di huang (the processed root of Rehmannia glutinosa Libosch.), chuan xiong (rhizome of Ligusticum chuanxiong Hort.), and bai shao (the root of Paeonia lactiflora f. pilosella (Nakai) Kitag.). Si-wu water extracts (SWE) have been used to treat blood deficiency. Components of one herb from SW have been reported to have anti-inflammatory and anti-obesity activities. However, there have been no reports about the effects of SWE on gut barrier damage. Therefore, the aim of the study was to explore the effect of SWE on gut barrier damage. In this study, we found that SWE effectively controlled body weight, liver weight, and feed efficiency, as well as decreased the serum TC level in HFD-fed mice. Moreover, SWE and rosiglitazone (Ros, positive control) increased the colonic alkaline phosphatase (ALP) level, down-regulated serum pro-inflammatory cytokine levels, and reduced intestinal permeability. In addition, SWE increased goblet cell numbers and mucus layer thickness to strengthen the mucus barrier. After supplementation with SWE and rosiglitazone, the protein expression of CHOP and GRP78 displayed a decrease, which improved the endoplasmic reticulum (ER) stress condition. Meanwhile, the increase in Cosmc and C1GALT1 improved the O-glycosylation process for correct protein folding. These results collectively demonstrated that SWE improved the mucus barrier, focusing on Muc2 mucin expression, in a prolonged high-fat diet, and provides evidence for the potential of SWE in the treatment of intestinal disease-associated mucus barrier damage.

Finasteride Alleviates High Fat Associated Protein-Overload Nephropathy by Inhibiting Trimethylamine N-Oxide Synthesis and Regulating Gut Microbiota

Unhealthy diet especially high-fat diet (HFD) is the major cause of hyperlipidemia leading to deterioration of chronic kidney diseases (CKD) in patients. Trimethylamine N-oxide (TMAO) is a gut-derived uremic toxin. Our previous clinical study demonstrated that the elevation of TMAO was positively correlated with CKD progression. Finasteride, a competitive and specific inhibitor of type II 5a-reductase, has been reported recently to be able to downregulate plasma TMAO level thus preventing the onset of atherosclerosis by our research group. In this study, we established a protein-overload nephropathy CKD mouse model by bovine serum albumin (BSA) injection to investigate whether hyperlipidemia could accelerate CKD progression and the underlying mechanisms. Finasteride was administrated to explore its potential therapeutic effects. The results of biochemical analyses and pathological examination showed that HFD-induced hyperlipidemia led to aggravated protein-overload nephropathy in mice along with an elevated level of circulating TMAO, which can be alleviated by finasteride treatment possibly through inhibition of Fmo3 in liver. The 16 S rRNA sequencing results indicated that HFD feeding altered the composition and distribution of gut microbiota in CKD mice contributing to the enhanced level of TMAO precursor TMA, while finasteride could exert beneficial effects via promoting the abundance of Alistipes_senegalensis and Akkermansia_muciniphila. Immunofluorescence staining (IF) and qRT-PCR results demonstrated the disruption of intestinal barrier by decreased expression of tight junction proteins including Claudin-1 and Zo-1 in HFD-fed CKD mice, which can be rescued by finasteride treatment. Cytokine arrays and redox status analyses revealed an upregulated inflammatory level and oxidative stress after HFD feeding in CKO mice, and finasteride-treatment could alleviate these lesions. To summarize, our study suggested that finasteride could alleviate HFD-associated deterioration of protein-overload nephropathy in mice by inhibition of TMAO synthesis and regulation of gut microbiota.

Proanthocyanidins at the gastrointestinal tract: mechanisms involved in their capacity to mitigate obesity-associated metabolic disorders

The prevalence of overweight and obesity is continually increasing worldwide. Obesity is a major public health concern given the multiple associated comorbidities. Finding dietary approaches to prevent/mitigate these conditions is of critical relevance. Proanthocyanidins (PACs), oligomers or polymers of flavan-3-ols that are extensively distributed in nature, represent a major part of total dietary polyphenols. Although current evidence supports the capacity of PACs to mitigate obesity-associated comorbidities, the underlying mechanisms remain speculative due to the complexity of PACs' structure. Given their limited bioavailability, the major site of the biological actions of intact PACs is the gastrointestinal (GI) tract. This review discusses the actions of PACs at the GI tract which could underlie their anti-obesity effects. These mechanisms include: i) inhibition of digestive enzymes at the GI lumen, including pancreatic lipase, α-amylase, α-glucosidase; ii) modification of gut microbiota composition; iii) modulation of inflammation- and oxidative stress-triggered signaling pathways, e.g. NF-κB and MAPKs; iv) protection of the GI barrier integrity. Further understanding of the mechanisms and biological activities of PACs at the GI tract can contribute to develop nutritional and pharmacological strategies oriented to mitigate the serious comorbidities of obesity.