Effect of Quercetin Monoglycosides on Oxidative Stress and Gut Microbiota Diversity in Mice with Dextran Sodium Sulphate-Induced Colitis

Evaluation of quercetin in alleviating the negative effects of high soybean meal diet on spotted sea bass Lateolabrax maculatus

The aim of this study was to investigate the effects of quercetin (QUE) on alleviating the negative effects of high soybean meal diet for spotted sea bass Lateolabrax maculatus. A healthy control group fed a 44% fishmeal diet was used, while the induction control group replaced 50% fishmeal with soybean meal. Subsequently, QUE was added at concentrations of 0.25, 0.50, 0.75, and 1.00 g/kg in the experimental groups. A total of 540 tailed spotted sea bass were randomly divided into 6 groups and fed the corresponding diet for 56 days. The results showed that 40% soybean meal significantly decreased the growth performance and immunity, increased the intestinal mucosal permeability, and caused damage to the intestinal tissue morphology; moreover, there were alterations observed in the composition of the intestinal microbiota, accompanied by detectable levels of saponins in the metabolites. However, the addition of QUE did not yield significant changes in growth performance; instead, it notably reduced the permeability of the intestinal mucosa, improved the body's immunity and the structural integrity of the intestinal tissue, increased the proportion of Proteobacteria, and enhanced the richness and diversity of intestinal microorganisms to a certain extent. In addition, QUE up-regulate the metabolism of amino acids and their derivatives and energy-related metabolites such as uridine and guanosine; furthermore, it appears to regulate transporters through the ABC transporters pathway to promote the absorption and utilization of QUE by enterocytes.

Dietary flavonoids-microbiota crosstalk in intestinal inflammation and carcinogenesis

Colorectal cancer (CRC) is currently the third leading cancer and commonly develops from chronic intestinal inflammation. A strong association was found between gut microbiota and intestinal inflammation and carcinogenic risk. Flavonoids, which are abundant in vegetables and fruits, can inhibit inflammation, regulate gut microbiota, protect gut barrier integrity, and modulate immune cell function, thereby attenuating colitis and preventing carcinogenesis. Upon digestion, about 90% of flavonoids are transported to the colon without being absorbed in the small intestine. This phenomenon increases the abundance of beneficial bacteria and enhances the production of short-chain fatty acids. The gut microbe further metabolizes these flavonoids. Interestingly, some metabolites of flavonoids play crucial roles in anti-inflammation and anti-tumor effects. This review summarizes the modulatory effect of flavonoids on gut microbiota and their metabolism by intestinal microbe under disease conditions, including inflammatory bowel disease, colitis-associated cancer (CAC), and CRC. We focus on dietary flavonoids and microbial interactions in intestinal mucosal barriers as well as intestinal immune cells. Results provide novel insights to better understand the crosstalk between dietary flavonoids and gut microbiota and support the standpoint that dietary flavonoids prevent intestinal inflammation and carcinogenesis.

Oxidative Stress, Inflammation, Gut Dysbiosis: What Can Polyphenols Do in Inflammatory Bowel Disease?

Inflammatory bowel disease (IBD) is a long-term, progressive, and recurrent intestinal inflammatory disorder. The pathogenic mechanisms of IBD are multifaceted and associated with oxidative stress, unbalanced gut microbiota, and aberrant immune response. Indeed, oxidative stress can affect the progression and development of IBD by regulating the homeostasis of the gut microbiota and immune response. Therefore, redox-targeted therapy is a promising treatment option for IBD. Recent evidence has verified that Chinese herbal medicine (CHM)-derived polyphenols, natural antioxidants, are able to maintain redox equilibrium in the intestinal tract to prevent abnormal gut microbiota and radical inflammatory responses. Here, we provide a comprehensive perspective for implementing natural antioxidants as potential IBD candidate medications. In addition, we demonstrate novel technologies and stratagems for promoting the antioxidative properties of CHM-derived polyphenols, including novel delivery systems, chemical modifications, and combination strategies.

Phytotherapy of mood disorders in the light of microbiota-gut-brain axis

BACKGROUND

Clinical research in natural product-based psychopharmacology has revealed a variety of promising herbal medicines that may provide benefit in the treatment of mild mood disorders, however failed to unambiguously indicate pharmacologically active constituents. The emerging role of the microbiota-gut-brain axis opens new possibilities in the search for effective methods of treatment and prevention of mood disorders.

PURPOSE

Considering the clinically proven effectiveness juxtaposed with inconsistencies regarding the indication of active principles for many medicinal plants applied in the treatment of anxiety and depression, the aim of the review is to look at their therapeutic properties from the perspective of the microbiota-gut-brain axis.

METHOD

A literature-based survey was performed using Scopus, Pubmed, and Google Scholar databases. The current state of knowledge regarding Hypericum perforatum, Valeriana officinalis, Piper methysticum, Passiflora incarnata, Humulus lupulus, Melissa officinalis, Lavandula officinalis, and Rhodiola rosea in terms of their antimicrobial activity, bioavailability, clinical effectiveness in depression/anxiety and gut microbiota - natural products interaction was summarized and analyzed.

RESULTS

Recent studies have provided direct and indirect evidence that herbal extracts and isolated compounds are potent modulators of gut microbiota structure. Additionally, some of the formed postbiotic metabolites exert positive effects and ameliorate depression-related behaviors in animal models of mood disorders. The review underlines the gap in research on natural products - gut microbiota interaction in the context of mood disorders.

CONCLUSION

Modification of microbiota-gut-brain axis by natural products is a plausible explanation of their therapeutic properties. Future studies evaluating the effectiveness of herbal medicine and isolated compounds in treating mild mood disorders should consider the bidirectional interplay between phytoconstituents and the gut microbiota community.

Polyphenols and inflammatory bowel disease: Natural products with therapeutic effects?

Inflammatory bowel disease (IBD) is a long-life disease with periods of recurrence and relief. Oxidative stress plays an important role in the pathogenesis of this disease. Recent years' studies in the field of IBD treatment mostly have focused on targeting cytokines and immune cell trafficking using antibodies and inhibitors, altering the composition of intestinal bacteria in the line of attenuation of inflammation using probiotics and prebiotics, and attenuating oxidative stress through antioxidant supplementation. Studies in animal models of IBD have shown that some polyphenolic compounds including curcumin, quercetin, resveratrol, naringenin, and epigallocatechin-3-gallate can affect almost all of the above aspects and are useful compounds in the treatment of IBD. Clinical studies performed on IBD patients have also confirmed the findings of animal model studies and have shown that supplementation with some of the above-mentioned polyphenolic compounds has positive effects in reducing disease clinical and endoscopic activity, inducing and maintaining remission, and improving quality of life. In this review article, in addition to a detailed reviewing the effects of the above-mentioned polyphenolic compounds on the events involved in the pathogenesis of IBD, the results of these clinical studies will also be reviewed.

Health-promoting foods and food crops of West-Africa origin: The bioactive compounds and immunomodulating potential

The rural communities of the sub-Sahara regions in Africa are rich in diverse indigenous culinary knowledge and foods, food crops, and condiments such as roots/tubers, cereal, legumes/pulses, locust beans, and green leafy vegetables. These food crops are rich in micronutrients and phytochemicals, which have the potentials to address hidden hunger as well as promote health when consumed. Some examples of these are fermented foods such as ogi and plants such as Vernonia amygdalina (bitter leaf), Zingiber officinales (garlic), Hibiscus sabdariffa (Roselle), and condiments. Food crops from West Africa contain numerous bioactive substances such as saponins, alkaloids, tannins, phenolics, flavonoids, and monoterpenoid chemicals among others. These bioresources have proven biological and pharmacological activities due to diverse mechanisms of action such as immunomodulatory, anti-inflammatory, antipyretic, and antioxidant activities which made them suitable as candidates for nutraceuticals and pharma foods. This review seeks to explore the different processes such as fermentation applied during food preparation and food crops of West-African origin with health-promoting benefits. The different bioactive compounds present in such food or food crops are discussed extensively as well as the diverse application, especially regarding respiratory diseases. PRACTICAL APPLICATIONS: The plants and herbs summarized here are more easily accessible and affordable by therapists and others having a passion for promising medicinal properties of African-origin plants.The mechanisms and unique metabolic potentials of African food crops discussed in this article will promote their applicability as a template molecule for novel drug discoveries in treatment strategies for emerging diseases. This compilation of antiviral plants will help clinicians and researchers bring new preventive strategies in combating COVID-19 like viral diseases, ultimately saving millions of affected people.

Dietary polyphenols in the treatment of inflammatory bowel diseases

Ulcerative colitis and Crohn's disease, caused by chronic inflammation in the digestive tract, are inflammatory bowel diseases and have similar symptoms. Abnormal immune responses play a pretty important role in the pathogenesis of the disease. Proinflammatory mediators trigger inflammation, stimulate cell signaling molecules, and induce disease onset. Corticosteroids, anti-tumor necrosis factor-α antibodies, and immunosuppressants are some drugs used to treat the disease. However, these drugs have some side effects. In addition, surgical methods might be used in the treatment, but these methods may have some complications. Due to the negative impact on treatment options, alternative methods for reliable, inexpensive, and effective treatment are being sought. Secondary plant compounds with an aromatic or phenolic ring structure, so-called polyphenols or phenolic compounds, may modulate cellular signaling pathways and reduce intestinal inflammation due to their antioxidant and anti-inflammatory effects. Polyphenols may be evaluated as alternative methods for inflammatory bowel disease based on these properties. This review aims to investigate the effect of some polyphenols on inflammatory bowel disease.

Impact of Clarified Apple Juices with Different Processing Methods on Gut Microbiota and Metabolomics of Rats

The consumption of processed foods has increased compared to that of fresh foods in recent years, especially due to the coronavirus disease 2019 pandemic. Here, we evaluated the health effects of clarified apple juices (CAJs, devoid of pectin and additives) processed to different degrees, including not-from-concentrate (NFC) and from-concentrate (FC) CAJs. A 56-day experiment including a juice-switch after 28 days was designed. An integrated analysis of 16S rRNA sequencing and untargeted metabolomics of cecal content were performed. In addition, differences in the CAJs tested with respect to nutritional indices and composition of small-molecule compounds were analyzed. The NFC CAJ, which showed a higher phenolic content resulting from the lower processing degree, could improve microbiota diversity and influence its structure. It also reduced bile acid and bilirubin contents, as well as inhibited the microbial metabolism of tryptophan in the gut. However, we found that these effects diminished with time by performing experiment extension and undertaking juice-switching. Our study provides evidence regarding the health effects of processed foods that can potentially be applied to public health policy decision making. We believe that NFC juices with a lower processing degree could potentially be healthier than FC juice.

Supplementation of polyphenol-rich grapes attenuates colitis, colitis-associated colon cancer and disease-associated dysbiosis in mice, but fails to mitigate colitis in antibiotic-treated mice

Polyphenols are known to interact with gut microbes that play key roles in maintaining gut health, but the role of gut microbiota modulation by polyphenols in mitigating colonic diseases is not fully established. We hypothesize that the interaction of polyphenols with the gut microbiota contributes to the attenuation of colitis and colitis-associated colon cancer (CAC). To test this hypothesis, we examined the effects of dietary supplementation of polyphenol-rich grape powder (GP) on azoxymethane (AOM) and dextran sulfate sodium (DSS)-induced colitis, CAC and the gut microbiota in mice (study 1), and further compared anti-colitis effects of GP in regular and antibiotic-treated mice (study 2). Compared to the control diet that has matched non-polyphenol contents, 10% GP, but not 3% GP, attenuated AOM-DSS induced colitis and tumor multiplicity by 29% (p<0.05). Ten percent GP increased gut bacterial evenness and counteracted CAC-induced decrease of bacterial evenness and changes of microbial composition. Remarkably, gut bacterial functional profiles of healthy mice and diseased mice fed 10% GP were similar, and both were significantly different from those of diseased mice with the control diet. Furthermore, 10% GP increased the relative abundance of butyrate-producing bacteria in the Lachnospiraceae family and enhanced the concentrations of fecal butyrate. Additionally, 10% GP mitigated DSS-induced colitis in conventional mice, but not the antibiotic-treated, gut microbe-depleted mice. Collectively, our studies demonstrate that grape polyphenols alleviate colonic diseases and prevent disease-associated dysbiosis, and their interaction with the gut microbiota may play a causative role in the protection of gut health.

Biological Activities Underlying the Therapeutic Effect of Quercetin on Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic autoimmune disorder stemming from unrestrained immune activation and subsequent destruction of colon tissue. Genetic susceptibility, microbiota remodeling, and environmental cues are involved in IBD pathogenesis. Up to now, there are limited treatment options for IBD, so better therapies for IBD are eagerly needed. The therapeutic effects of naturally occurring compounds have been extensively investigated, among which quercetin becomes an attractive candidate owing to its unique biochemical properties. To facilitate the clinical translation of quercetin, we aimed to get a comprehensive understanding of the cellular and molecular mechanisms underlying the anti-IBD role of quercetin. We summarized that quercetin exerts the anti-IBD effect through consolidating the intestinal mucosal barrier, enhancing the diversity of colonic microbiota, restoring local immune homeostasis, and restraining the oxidative stress response. We also delineated the effect of quercetin on gut microbiome and discussed the potential side effects of quercetin administration. Besides, quercetin could serve as a prodrug, and the bioavailability of quercetin is improved through chemical modifications or the utilization of effective drug delivery systems. Altogether, these lines of evidence hint the feasibility of quercetin as a candidate compound for IBD treatment.

Anti-Inflammatory Activity of Mulberry Leaf Flavonoids In Vitro and In Vivo

Mulberry (Morus alba L.) is a flowering tree traditionally used in Chinese herbal medicine. Mulberry leaf flavonoids (MLFs) have been reported to exert important anti-inflammatory and antioxidant properties. The purpose of this study was to select the MLF with the best anti-inflammatory and antioxidative activities from MLFs eluted by different ethanol concentrations (30%, 50%, and 75%) and explore its pharmacological properties. Three types of MLFs inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and inflammatory cytokines in lipopolysaccharide (LPS)-induced RAW 264.7 cells. All MLFs boosted the antioxidative capacity by decreasing the reactive oxygen species (ROS) production and the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and improving the metal ion chelating activity and reducing power. The results revealed that the MLFs eluted by 30% ethanol exhibited the best anti-inflammatory and antioxidative activities. A nontargeted metabolomic analysis was used to analyze 24 types of differential flavonoids between the MLFs. Quercetin, kaempferol, and their derivatives in 30%MLF were more abundant than the other two MLFs. Furthermore, we evaluated the pharmacological activities of 30%MLF in dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) mice. The 30%MLF could alleviate the clinical symptoms, reduce the secretion of inflammatory cytokines, and inhibit the activation of the inflammatory pathway in DSS-induced colitis mice. This study will provide valuable information for the development of MLFs eluted by 30% ethanol as a functional food.

Therapeutic Potential of Quercetin Loaded Nanoparticles: Novel Insights in Alleviating Colitis in an Experimental DSS Induced Colitis Model

Oxidative stress is considered the main etiologic factor involved in inflammatory bowel disease (IBD). Integration of nanocarriers for natural therapeutic agents with antioxidant and anti-inflammatory potential is a novel promising candidate for curing IBD. Herein, the colonic antioxidant and anti-inflammatory effects of different concentrations of quercetin nanoparticles (QT-NPs) were evaluated using a dextran sulfate sodium (DSS)-induced colitis model. Following colitis induction, the efficacy and mechanistic actions of QT-NPs were evaluated by assessing lesion severity, molecular aids controlling oxidative stress and inflammatory response, and histopathological and immunohistochemistry examination of colonic tissues. Administration of QT-NPs, especially at higher concentrations, significantly reduced the disease activity index and values of fecal calprotectin marker compared to the colitic group. Colonic oxidant/antioxidant status (ROS, H₂O₂, MDA, SOD, CAT, GPX and TAC) was restored after treatment with higher concentrations of QT-NPs. Moreover, QT-NPs at levels of 20 mg/kg and, to a lesser extent, 15 mg/kg reduced Nrf2 and HO-1 gene expression, which was in line with decreasing the expression of iNOS and COX2 in colonic tissues. Higher concentrations of QT-NPs greatly downregulated pro-inflammatory cytokines; upregulated genes encoding occludin, MUC-2 and JAM; and restored the healthy architectures of colonic tissues. Taken together, these data suggest that QT-NPs could be a promising alternative to current IBD treatments.

Quercetin Reduces Inflammation and Protects Gut Microbiota in Broilers

The aim of this study was to investigate the effects of quercetin on inflammatory response and intestinal microflora in broiler chicken jejuna. A total of 120 broiler chickens were allocated into 3 groups: saline-challenged broilers fed a basal diet (CTR group), lipopolysaccharide (LPS)-challenged broilers fed a basal diet (L group) and LPS-challenged broilers fed a basal diet supplemented with 200 mg/kg quercetin (LQ group). Our results showed that LPS significantly increased expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, interferon (IFN)-γ, toll-like receptor (TLR)-4, Bax, Caspase-3 and diamine oxidase activity (DAO), and decreased expression of zona occludens-1 (ZO-1), Occludin and Bcl-2 in the jejunum, while dietary quercetin prevented the adverse effects of LPS injection. LPS injection significantly decreased the number of Actinobacteria, Armatimonadetes and Fibrobacteriae at the phylum level when compared to the CTR group. Additionally, at genus level, compared with the CTR group, the abundance of Halomonas, Micromonospora, Nitriliruptor, Peptococcus, Rubellimicrobium, Rubrobacter and Slaclda in L group was significantly decreased, while dietary quercetin restored the numbers of these bacteria. In conclusion, our results demonstrated that dietary quercetin could alleviate inflammatory responses of broiler chickens accompanied by modulating jejunum microflora.

More Prominent Inflammatory Response to Pachyman than to Whole-Glucan Particle and Oat-β-Glucans in Dextran Sulfate-Induced Mucositis Mice and Mouse Injection through Proinflammatory Macrophages

(1→3)-β-D-glucans (BG) (the glucose polymers) are recognized as pathogen motifs, and different forms of BGs are reported to have various effects. Here, different BGs, including Pachyman (BG with very few (1→6)-linkages), whole-glucan particles (BG with many (1→6)-glycosidic bonds), and Oat-BG (BG with (1→4)-linkages), were tested. In comparison with dextran sulfate solution (DSS) alone in mice, DSS with each of these BGs did not alter the weight loss, stool consistency, colon injury (histology and cytokines), endotoxemia, serum BG, and fecal microbiome but Pachyman-DSS-treated mice demonstrated the highest serum cytokine elicitation (TNF-α and IL-6). Likewise, a tail vein injection of Pachyman together with intraperitoneal lipopolysaccharide (LPS) induced the highest levels of these cytokines at 3 h post-injection than LPS alone or LPS with other BGs. With bone marrow-derived macrophages, BG induced only TNF-α (most prominent with Pachyman), while LPS with BG additively increased several cytokines (TNF-α, IL-6, and IL-10); inflammatory genes (iNOS, IL-1β, Syk, and NF-κB); and cell energy alterations (extracellular flux analysis). In conclusion, Pachyman induced the highest LPS proinflammatory synergistic effect on macrophages, followed by WGP, possibly through Syk-associated interactions between the Dectin-1 and TLR-4 signal transduction pathways. Selection of the proper form of BGs for specific clinical conditions might be beneficial.

Putative Mechanisms Underlying the Beneficial Effects of Polyphenols in Murine Models of Metabolic Disorders in Relation to Gut Microbiota

The beneficial effects of polyphenols on metabolic disorders have been extensively reported. The interaction of these compounds with the gut microbiota has been the focus of recent studies. In this review, we explored the fundamental mechanisms underlying the beneficial effects of polyphenols in relation to the gut microbiota in murine models of metabolic disorders. We analyzed the effects of polyphenols on three murine models of metabolic disorders, namely, models of a high-fat diet (HFD)-induced metabolic disorder, dextran sulfate sodium (DSS)-induced colitis, and a metabolic disorder not associated with HFD or DSS. Regardless of the model, polyphenols ameliorated the effects of metabolic disorders by alleviating intestinal oxidative stress, improving inflammatory status, and improving intestinal barrier function, as well as by modulating gut microbiota, for example, by increasing the abundance of short-chain fatty acid-producing bacteria. Consequently, polyphenols reduce circulating lipopolysaccharide levels, thereby improving inflammatory status and alleviating oxidative imbalance at the lesion sites. In conclusion, polyphenols likely act by regulating intestinal functions, including the gut microbiota, and may be a safe and suitable therapeutic agent for various metabolic disorders.

Polyphenols as modulators of pre-established gut microbiota dysbiosis: State-of-the-art

The human intestine contains an intricate ecological community of bacteria, referred as the gut microbiota, which plays a pivotal role in the host homeostasis. Multiple factors could interfere with this delicate balance, thus causing a disruption of the microbiota equilibrium, the so called dysbiosis. Gut microbiota dysbiosis is involved in gastrointestinal and extra-intestinal metabolic diseases, as obesity and diabetes. Polyphenols, present in a broad range of plant foods, are known to have numerous health benefits; however, their beneficial effect on pre-existing dysbiosis is less clear. Indeed, in most of the conducted animal studies the administration of polyphenols or foods rich in polyphenols occurred simultaneously with the induction of the pathology to be examined, then analyzing the preventive action of the polyphenols on the onset of dysbiosis, while very low studies analyzed the modulatory activity of polyphenols on the pre-existing dysbiosis. For this reason, the present review aims to update the current information about the modulation of the pre-established gut microbiota dysbiosis by dietary phenolic compounds in a broad range of disorders in both animal studies and human trials, distinguishing the preventive or treatment approaches in animal studies. The described studies highlight that dietary polyphenols, exerting prebiotic-like effects, can modulate the pre-existing dysbiosis stimulating the growth of beneficial bacteria and inhibiting pathogenic bacteria in both animal models and humans. Anyway, most of the conducted studies are related to obesity and metabolic syndrome, and so further studies are needed to understand this polyphenols' ability in relation to other pathologies.

Quercetin extracted from Sophora japonica flower improves growth performance, nutrient digestibility, cecal microbiota, organ indexes, and breast quality in broiler chicks

Objective

The objective of this study was to evaluate the effects of supplementing quercetin extracted from Sophora japonica flower (QS) to the diet of broiler chicks on their growth performance, apparent nutrient digestibility, cecal microbiota, serum lipid profiles, relative organ weight, and breast muscle quality.

Method

A total of 1088 1-day-old broiler chicks (mixed sex) were randomly assigned to four groups based on the initial body weight (43.00 ± 0.29 g). The experimental period was 35 days (starter, days 0-7; grower, days 7-21; finisher, days 21-35). There were 17 replicate cages per treatment and 16 birds per cage. Dietary treatments consisted of birds receiving basal diet without quercetin as the control group and treatment groups consisted of birds fed basal diet supplemented with 0.2, 0.4, or 0.6 g/kg QS.

Results

With the increase of the QS dosage, body weight gain during days 0-7 (P = 0.021), 7-21 (P = 0.010), and 1-35 (P = 0.045), feed intake during days 0-7 (P = 0.037) and 1-35 (P = 0.025), apparent dry matter digestibility (P = 0.008), apparent energy retention (P = 0.004), cecal lactic acid bacteria counts (P = 0.023), the relative weight of breast muscle (P = 0.014), pH value from breast muscle (P < 0.001), and the water holding capacity of breast muscle (P = 0.012) increased linearly, whereas the drip loss from breast muscle (P = 0.001) decreased linearly.

Conclusion

The addition of QS in the diet of broiler chicks had positive effects on the breast muscle yield and breast muscle quality, and improved the dry matter digestibility and energy retention by increasing cecal beneficial bacteria counts, thus improving growth performance.

A Novel Pathway of Flavonoids Protecting against Inflammatory Bowel Disease: Modulating Enteroendocrine System

Inflammatory bowel disease (IBD) is a comprehensive term for chronic or relapsing inflammatory diseases occurring in the intestinal tract, generally including Crohn's disease (CD) and ulcerative colitis (UC). Presently, the pathogenesis of IBD is unknown, yet multiple factors have been reported to be related with the development of IBD. Flavonoids are phytochemicals with biological activity, which are ubiquitously distributed in edible plants, such as fruits and vegetables. Recent studies have demonstrated impressively that flavonoids have anti-IBD effects through multiple mechanisms. These include anti-inflammatory and antioxidant actions; the preservation of the epithelial barrier integrity, the intestinal immunomodulatory property, and the shaping microbiota composition and function. In addition, a few studies have shown the impact of flavonoids on enterohormones release; nonetheless, there is hardly any work showing the link between flavonoids, enterohormones release and IBD. So far, the interaction between flavonoids, enterohormones and IBD is elucidated for the first time in this review. Furthermore, the inference can be drawn that flavonoids may protect against IBD through modulating enterohormones, such as glucagon-like peptide 1 (GLP-1), GLP-2, dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors), ghrelin and cholecystokinin (CCK). In conclusion, this manuscript explores a possible mechanism of flavonoids protecting against IBD.

The Potential Role of Phytonutrients Flavonoids Influencing Gut Microbiota in the Prophylaxis and Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), characterized by the chronic inflammation of the gastrointestinal tract, is comprised of two idiopathic chronic intestinal inflammatory diseases. As the incidence of IBD increases, so does the need for safe and effective treatments. Trillions of microorganisms are colonized in the mammalian intestine, coevolve with the host in a symbiotic relationship. Gut microbiota has been reported to be involved in the pathophysiology of IBD. In this regard, phytonutrients flavonoids have received increasing attention for their anti-oxidant and anti-inflammatory activities. In this review, we address recent advances in the interactions among flavonoids, gut microbiota, and IBD. Moreover, their possible potential mechanisms of action in IBD have been discussed. We conclude that there is a complex interaction between flavonoids and gut microbiota. It is expected that flavonoids can change or reshape the gut microbiota to provide important considerations for developing treatments for IBD.

Dietary Quercetin Supplementation Attenuates Diarrhea and Intestinal Damage by Regulating Gut Microbiota in Weanling Piglets

Antioxidant polyphenols from plants are potential dietary supplementation to alleviate early weaning-induced intestinal disorders in piglets. Recent evidences showed polyphenol quercetin could reshape gut microbiota when it functioned as anti-inflammation or antioxidation agents in rodent models. However, the effect of dietary quercetin supplementation on intestinal disorders and gut microbiota of weanling piglets, along with the role of gut microbiota in this effect, both remain unclear. Here, we determined the quercetin's effect on attenuating diarrhea, intestinal damage, and redox imbalance, as well as the role of gut microbiota by transferring the quercetin-treated fecal microbiota to the recipient piglets. The results showed that dietary quercetin supplementation decreased piglets' fecal scores improved intestinal damage by increasing tight junction protein occludin, villus height, and villus height/crypt depth ratio but decreased crypt depth and intestinal epithelial apoptosis (TUNEL staining). Quercetin also increased antioxidant capacity indices, including total antioxidant capacity, catalase, and glutathione/oxidized glutathione disulfide but decreased oxidative metabolite malondialdehyde in the jejunum tissue. Fecal microbiota transplantation (FMT) from quercetin-treated piglets had comparable effects on improving intestinal damage and antioxidative capacity than dietary quercetin supplementation. Further analysis of gut microbiota using 16S rDNA sequencing showed that dietary quercetin supplementation or FMT shifted the structure and increased the diversity of gut microbiota. Especially, anaerobic trait and carbohydrate metabolism functions of gut microbiota were enriched after dietary quercetin supplementation and FMT, which may owe to the increased antioxidative capacity of intestine. Quercetin increased the relative abundances of Fibrobacteres, Akkermansia muciniphila, Clostridium butyricum, Clostridium celatum, and Prevotella copri but decreased the relative abundances of Proteobacteria, Lactobacillus coleohominis, and Ruminococcus bromii. Besides, quercetin-shifted bacteria and carbohydrate metabolites short chain fatty acids were significantly related to the indices of antioxidant capacity and intestinal integrity. Overall, dietary quercetin supplementation attenuated diarrhea and intestinal damage by enhancing the antioxidant capacity and regulating gut microbial structure and metabolism in piglets.

Potential Implications of Citrulline and Quercetin on Gut Functioning of Monogastric Animals and Humans: A Comprehensive Review

The importance of gut health in animal welfare and wellbeing is undisputable. The intestinal microbiota plays an essential role in the metabolic, nutritional, physiological, and immunological processes of animals. Therefore, the rapid development of dietary supplements to improve gut functions and homeostasis is imminent. Recent studies have uncovered the beneficial effects of dietary supplements on the immune response, microbiota, gut homeostasis, and intestinal health. The application of citrulline (a functional gut biomarker) and quercetin (a known potent flavonoid) to promote gut functions has gained considerable interest as both bioactive substances possess anti-inflammatory, anti-oxidative, and immunomodulatory properties. Research has demonstrated that both citrulline and quercetin can mediate gut activities by combating disruptions to the intestinal integrity and alterations to the gut microbiota. In addition, citrulline and quercetin play crucial roles in maintaining intestinal immune tolerance and gut health. However, the synergistic benefits which these dietary supplements (citrulline and quercetin) may afford to simultaneously promote gut functions remain to be explored. Therefore, this review summarizes the modulatory effects of citrulline and quercetin on the intestinal integrity and gut microbiota, and further expounds on their potential synergistic roles to attenuate intestinal inflammation and promote gut health.

Positive Synergistic Effects of Quercetin and Rice Bran on Human Gut Microbiota Reduces Enterobacteriaceae Family Abundance and Elevates Propionate in a Bioreactor Model

Dietary fiber and flavonoids have substantial influence on the human gut microbiota composition that significantly impact health. Recent studies with dietary supplements such as quercetin and rice bran have shown beneficial impacts on the host alongside a positive influence of the gut microbiota. The specific bacterial species impacted by quercetin or rice bran in the diet is not well understood. In this study, we used a minibioreactor array system as a model to determine the effect of quercetin and rice bran individually, as well as in combination, on gut microbiota without the confounding host factors. We found that rice bran exerts higher shift in gut microbiome composition when compared to quercetin. At the species level, Acidaminococcus intestini was the only significantly enriched taxa when quercetin was supplemented, while 15 species were enriched in rice bran supplementation and 13 were enriched when quercetin and rice bran were supplemented in combination. When comparing the short chain fatty acid production, quercetin supplementation increased isobutyrate production while propionate dominated the quercetin and rice bran combined group. Higher levels of propionate were highly correlated to the lower abundance of the potentially pathogenic Enterobacteriaceae family. These findings suggest that the combination of quercetin and rice bran serve to enrich beneficial bacteria and reduce potential opportunistic pathogens. In vivo studies are necessary to determine how this synergy of quercetin and rice bran on microbiota impact host health.

Eugenol Alleviates Dextran Sulfate Sodium-Induced Colitis Independent of Intestinal Microbiota in Mice

The present study investigated the effect of eugenol (EUG) on dextran sulfate sodium (DSS)-induced colitis and explored the underlying mechanisms. C57BL/6 mice were intragastrically administered normal saline or EUG (20 mg/kg body weight) for 17 days, and colitis was induced by using 3% DSS from day 7. The results showed that EUG increased the body weight and reduced the disease activity index score and colon pathological scores in DSS-treated mice (P < 0.05). Further, EUG preserved the proinflammatory cytokines (interleukin (IL)-6, -12, -21, and -23), lowered (P < 0.05) colonic malondialdehyde (MDA), uncoupling protein 2 (UCP2) expression and p65 phosphorylation, and activated (P < 0.05) colonic kelch-like ECH-associated protein 1 and nuclear factor (erythroid-derived 2)-like 2 expressions but did not affect the intestinal microbiota in DSS-treated mice. Furthermore, EUG ameliorated colitis in antibiotic-treated mice, while fecal microbiota transplantation from EUG preadministered mice failed to ameliorate colitis. In conclusion, EUG could alleviate colitis by attenuating colonic inflammation and oxidative stress independent of intestinal microbiota.

Recent Advances in Bioactive Compounds, Health Functions, and Safety Concerns of Onion (Allium cepa L.)

Onion (Allium cepa L.) is a common vegetable, widely consumed all over the world. Onion contains diverse phytochemicals, including organosulfur compounds, phenolic compounds, polysaccharides, and saponins. The phenolic and sulfur-containing compounds, including onionin A, cysteine sulfoxides, quercetin, and quercetin glucosides, are the major bioactive constituents of onion. Accumulated studies have revealed that onion and its bioactive compounds possess various health functions, such as antioxidant, antimicrobial, anti-inflammatory, anti-obesity, anti-diabetic, anticancer, cardiovascular protective, neuroprotective, hepatorenal protective, respiratory protective, digestive system protective, reproductive protective, and immunomodulatory properties. Herein, the main bioactive compounds in onion are summarized, followed by intensively discussing its major health functions as well as relevant molecular mechanisms. Moreover, the potential safety concerns about onion contamination and the ways to mitigate these issues are also discussed. We hope that this paper can attract broader attention to onion and its bioactive compounds, which are promising ingredients in the development of functional foods and nutraceuticals for preventing and managing certain chronic diseases.

Canna x generalis L.H. Bailey rhizome extract ameliorates dextran sulfate sodium-induced colitis via modulating intestinal mucosal dysfunction, oxidative stress, inflammation, and TLR4/ NF-ҡB and NLRP3 inflammasome pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Genus Canna is used in folk medicine as demulcent, diaphoretic, antipyretic, mild laxative and in gastrointestinal upsets therapy. Canna x generalis (CG) L.H. Bailey is traditionally used as anti-inflammatory, analgesic and antipyretic. Besides, CG is used in Ayurvedic medicines' preparations and in the treatment of boils, wounds, and abscess. Nevertheless, its anti-inflammatory effects against ulcerative colitis (UC) are not yet investigated.

AIM

This study aimed to investigate the phytoconstituents of CG rhizome ethanol extract (CGE). Additionally, we aimed to comparatively evaluate its therapeutic effects and underlying mechanisms against the reference drug "sulphasalazine (SAS)" in dextran sodium sulfate (DSS)-induced UC in mice.

MATERIAL AND METHODS

Metabolic profiling of CG rhizomes was performed via UHPLC/qTOF-HRMS; the total phenolic, flavonoid and steroid contents were determined, and the main phytoconstituents were isolated and identified. Next, DSS-induced (4%) acute UC was established in C57BL/6 mice. DSS-induced mice were administered either CGE (100 and 200 mg/kg) or SAS (200 mg/kg) for 7 days. Body weight, colon length, disease activity index (DAI) and histopathological alterations in colon tissues were examined. Colon levels of oxidative stress (GSH, MDA, SOD and catalase) and pro-inflammatory [Myeloperoxidase (MPO), nitric oxide (NO), IL-1β, IL-12, TNF-α, and INF-γ] markers were colourimetrically determined. Serum levels of lipopolysaccharide (LPS) and relative mRNA expressions of occludin, TLR4 and ASC (Apoptosis-Associated Speck-Like Protein Containing CARD) using RT-PCR were measured. Protein levels of NLRP3 inflammasome and cleaved caspase-1 were determined by Western blot. Furthermore, immunohistochemical examinations of caspase-3, NF-ҡB and claudin-1 were performed.

RESULTS

Major identified constituents of CGE were flavonoids, phenolic acids, phytosterols, beside five isolated phytoconstituents (β-sitosterol, triacontanol fatty alcohol, β-sitosterol-3-O-β-glucoside, rosmarinic acid, 6-O-p-coumaroyl-β-D-fructofuranosyl α-D-glucopyranoside). The percentage of the phenolic, flavonoid and steroid contents in CGE were 20.55, 6.74 and 98.09 μg of gallic acid, quercetin and β-sitosterol equivalents/mg extract, respectively. In DSS-induced mice, CGE treatment ameliorated DAI, body weight loss and colon shortening. CGE attenuated the DSS-induced colonic histopathological alternations, inflammatory cell infiltration and histological scores. CGE elevated GSH, SOD and catalase levels, and suppressed MDA, pro-inflammatory mediators (MPO and NO) as well as cytokines levels in colonic tissues. Moreover, CGE downregulated LPS/TLR4 signaling, caspase-3 and NF-ҡB expressions. CGE treatment inhibited NLRP3 signaling pathway as indicated by the suppression of the protein expression of NLRP3 and cleaved caspase-1, and the ASC mRNA expression in colonic tissues. Additionally, CGE restored tight junction proteins' (occludin and claudin-1) expressions.

CONCLUSION

Our findings provided evidence for the therapeutic potential of CGE against UC. CGE restored intestinal mucosal barrier's integrity, mitigated oxidative stress, inflammatory cascade, as well as NF-ҡB/TLR4 and NLRP3 pathways activation in colonic tissues. Notably, CGE in a dose of 200 mg/kg was more effective in ameliorating DSS-induced UC as compared to SAS at the same dose.

Efficacy and Safety of Sophora flavescens (Kushen) Based Traditional Chinese Medicine in the Treatment of Ulcerative Colitis: Clinical Evidence and Potential Mechanisms

Background: Radix Sophorae flavescentis (Kushen), a Chinese herb, is widely used in the treatment of ulcerative colitis (UC) with damp-heat accumulation syndrome (DHAS) according to traditional Chinese medicine (TCM) theory. Objective: The aim of this study was to illuminate the clinical efficacy and potential mechanisms of Kushen-based TCM formulations in the treatment of UC with DHAS. Materials and Methods: A systematic literature search was performed in the PubMed, EMBASE, Chinese Biomedical Literature database, China National Knowledge Infrastructure database, Chongqing VIP Information database, and Wanfang database for articles published between January 2000 and July 2020 on randomized controlled trials (RCTs) that used Kushen-based TCM formulations in the treatment of UC with DHAS. A network pharmacology approach was conducted to detect the potential pathways of Kushen against UC with DHAS. Results: Eight RCTs with a total of 983 subjects were included in the meta-analysis. Compared with the control subjects (5-aminosalicylic acid therapy), those who received Kushen-based TCM formulations for the treatment of UC showed a significantly higher clinical remission rate (RR = 1.20, 95% CI: [1.04, 1.38], p = 0.02) and lower incidence of adverse events (RR = 0.63, 95% CI [0.39, 1.01], p = 0.06). A component-target-pathway network was constructed, indicating five main components (quercetin, luteolin, matrine, formononetin, and phaseolin), three major targets (Interleukin-6, Myc proto-oncogene protein, and G1/S-specific cyclin-D1) and one key potential therapeutic pathway (PI3K-Akt signaling) of Kushen against UC with DHAS. Conclusion: Kushen-based TCM formulations provide good efficacy and possess great potential in the treatment of UC. Large-scale and high-quality clinical trials and experimental verification should be considered for further confirmation of the efficacy of Kushen-based formulations.

Apple polyphenols extract alleviated dextran sulfate sodium-induced ulcerative colitis in C57BL/6 male mice by restoring bile acid metabolism disorder and gut microbiota dysbiosis

To investigate and compare the preventive effects of apple polyphenols extract (APE) with phloretin on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC), 60 male mice were treated with 125 or 500 mg/(kg bw d) APE or 100 mg/(kg bw d) phloretin, the single-ingredient of APE, for continuous 3 weeks by intragastric administration, meanwhile, mice were provided with 3% DSS dissolved in drinking water to induce UC during the third week. Both APE and phloretin significantly ameliorated DSS-induced UC by inhibiting body weight loss, preventing colon shortening and mucosa damage. Except the same mechanisms of the inhibited activation of NF-κB signaling, decreased hyodeoxycholic acid level and increased abundance of Verrucomicrobia at phylum and Bacteroides and Akkermansia at genus, APE increased β-muricholic acid level and decreased Bacterodetes abundance, while phloretin decreased Firmicutes abundance. Furthermore, APE treatment showed much lower disease activity index score, less body weight loss and lighter spleen than phloretin. Thus, our study supported the potentiality of APE as a promising dietary intervention for the prevention of experimental UC.

Berberine Administration in Treatment of Colitis: A Review

Berberine (Brb) is one of the well-known naturally occurring compounds exclusively found in Berberis vulgaris and other members of this family, such as Berberis aristata, Berberis aroatica, and Berberis aquifolium. This plant-derived natural compound has a variety of therapeutic impacts, including anti-oxidant, anti-inflammatory, anti-diabetic, and anti-tumor. Multiple studies have demonstrated that Brb has great anti-inflammatory activity and is capable of reducing the levels of proinflammatory cytokines, while it enhances the concentrations of anti-inflammatory cytokines, making it suitable for the treatment of inflammatory disorders. Colitis is an inflammatory bowel disease with chronic nature. Several factors are involved in the development of colitis and it appears that inflammation and oxidative stress are the most important ones. With respect to the anti-inflammatory and antioxidant effects of Brb, its administration seems to be beneficial in the treatment of colitis. In the present review, the protective effects of Brb in colitis treatment and its impact on molecular pathways are discussed.

Glutamine relieves oxidative stress through PI3K/Akt signaling pathway in DSS-induced ulcerative colitis mice

Objective(s):

Ulcerative colitis (UC) is a kind of complex immune disease, and a major cause of destruction of intestinal barrier and oxidative stress in this field. In this paper, glutamine (Gln) was believed to offer protection against oxidative stress injury in colitis mice.

Materials and Methods:

Thirty mice were randomly assigned into control, model, LY294002 (PI3K/Akt inhibitor), Gln, Gln+LY294002 and 5-Aminosalicylic acid (5-ASA) groups. The mice in the experimental group drank 4% dextran sulfate sodium salt (DSS) for 7 consecutive days. The protective effect of Gln on oxidative stress was quantified by keeping colitis mice, involving Phosphatidylinositol-3-kinase (PI3K)/Protein kinase B (Akt)/mammalian target of Rapamycin (mTOR) signaling pathway, with different medications or distilled water through intragastric administration for 10 consecutive days.

Results:

In vivo administration of Gln, LY294002 or 5-ASA was found to ameliorate the symptoms of colitis in mice, such as reduced growth, loose stools and stool bleeding; protected DSS-induced colitis mice from goblet cell loss, lymphocytosis, mucosal erosion, loss of crypts, and neutrophil infiltration; improved the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-XP); decreased the content of malondialdehyde (MDA); and inhibited the activation of PI3K/Akt signaling pathway.

Conclusion:

Administration of Gln to the DSS-induced colitis mice led to a clearly reduction in oxidative stress-induced injury. The Gln is confirmed as inhibiting the PI3K/Akt signaling pathway activity.

Roles of the Polyphenol-Gut Microbiota Interaction in Alleviating Colitis and Preventing Colitis-Associated Colorectal Cancer

Accumulating evidence indicates that the gut microbiota can promote or inhibit colonic inflammation and carcinogenesis. Promotion of beneficial gut bacteria is considered a promising strategy to alleviate colonic diseases including colitis and colorectal cancer. Interestingly, dietary polyphenols, which have been shown to attenuate colitis and inhibit colorectal cancer in animal models and some human studies, appear to reach relatively high concentrations in the large intestine and to interact with the gut microbial community. This review summarizes the modulatory effects of polyphenols on the gut microbiota in humans and animals under healthy and diseased conditions including colitis and colitis-associated colorectal cancer (CAC). Existing human and animal studies indicate that polyphenols and polyphenol-rich whole foods are capable of elevating butyrate producers and probiotics that alleviate colitis and inhibit CAC, such as Lactobacillus and Bifidobacterium. Studies in colitis and CAC models indicate that polyphenols decrease opportunistic pathogenic or proinflammatory microbes and counteract disease-induced dysbiosis. Consistently, polyphenols also change microbial functions, including increasing butyrate formation. Moreover, polyphenol metabolites produced by the gut microbiota appear to have anticancer and anti-inflammatory activities, protect gut barrier integrity, and mitigate inflammatory conditions in cells and animal models. Based on these results, we conclude that polyphenol-mediated alteration of microbial composition and functions, together with polyphenol metabolites produced by the gut microbiota, likely contribute to the protective effects of polyphenols on colitis and CAC. Future research is needed to validate the causal role of the polyphenol-gut microbiota interaction in polyphenols' anti-colitis and anti-CAC effects, and to further elucidate mechanisms underlying such interaction.

Acute Diarrhea in Dogs: Current Management and Potential Role of Dietary Polyphenols Supplementation

Acute diarrhea is one of the most common reasons why pet owners seek veterinary care for their canine companions. In many cases, signs resolve spontaneously or with symptomatic therapy without a specific cause being discovered. However, life-threatening cases can occur. The etiology is complex, including infectious diseases (endoparasites, virus, bacteria, protozoa, fungal agents) by both zoonotic and non-zoonotic pathogens, dietary indiscretion, endocrine diseases, and stress (e.g., travel or environmental changes). In the last years, the role played by oxidative stress in the pathogenesis of acute and chronic enteropathies, independently from the initial noxa, has been highlighted by many researches in both humans and animals. As a result, a series of dietary antioxidant compounds have been studied for their potential use in the treatment of intestinal inflammation. This review summarizes the traditional therapeutic and nutritional options to manage canine acute diarrhea, highlighting the need to explore the role of oxidative stress and potential antioxidant supplementation, especially polyphenols, during acute diarrheic episodes.

Effects of dietary quercetin on the antioxidative status and cecal microbiota in broiler chickens fed with oxidized oil

This study was conducted to evaluate the effects of quercetin on the antioxidant ability, intestinal barrier functions, and cecal microbiota in broiler chickens fed with oxidized soya oil. Four hundred eighty male Arbor Acres broilers were randomly assigned to 5 treatments, each involving 8 cages (12 birds per cage). The treatment groups were as follows: the control group, birds fed with basal diets containing oxidized oil, and birds fed with basal diets containing oxidized oil and supplemented with 200 ppm of quercetin, 400 ppm of quercetin, and 800 ppm of quercetin. The results showed that dietary supplementation with quercetin at a dose of 400 ppm or 800 ppm alleviated the increased serum malondialdehyde (MDA) level induced by oxidized oil on day 11 (P = 0.005) and reversed the increased MDA level in the mucosa on day 11 (P = 0.021). Quercetin significantly upregulated the transcription of nuclear factor erythroid 2–related factor 2 (Nrf2) and its downstream genes such as catalase (P < 0.001), superoxide dismutase 1 (P < 0.001), glutathione peroxidase 2 (P = 0.018), heme oxygenase-1 (HO-1) (P = 0.0), and thioredoxin (P = 0.002) and reversed the mRNA expression of HO-1 (P = 0.007) in the ileal mucosa. Tight junction protein 1 was only downregulated by oxidized oil (P = 0.013). In addition, quercetin (800 ppm) alleviated the decreased mRNA expression of mucin 2 (MUC2), which contributed to the intestinal chemical barrier (P = 0.039). The supplemental dose of 400 ppm of quercetin was able to promote Lactobacillus in the cecum, which enhanced the gastrointestinal tract health. In summary, these results indicated that quercetin ameliorated the oxidized oil–induced oxidative stress by upregulating the transcription of Nrf2 and its downstream genes to restore redox balance and reinforced the intestinal barrier via higher expression and secretion of MUC2 and facilitating the growth of Lactobacillus in the cecum. Therefore, quercetin could be a potential feed additive that can be applied in poultry production for amelioration of oxidative stress caused by oxidized oil and preventing the potential invasion of exogenous pathogens.

Intestinal Ca2+ absorption revisited: A molecular and clinical approach

Ca2+ has an important role in the maintenance of the skeleton and is involved in the main physiological processes. Its homeostasis is controlled by the intestine, kidney, bone and parathyroid glands. The intestinal Ca2+ absorption occurs mainly via the paracellular and the transcellular pathways. The proteins involved in both ways are regulated by calcitriol and other hormones as well as dietary factors. Fibroblast growth factor 23 (FGF-23) is a strong antagonist of vitamin D action. Part of the intestinal Ca2+ movement seems to be vitamin D independent. Intestinal Ca2+ absorption changes according to different physiological conditions. It is promoted under high Ca2+ demands such as growth, pregnancy, lactation, dietary Ca2+ deficiency and high physical activity. In contrast, the intestinal Ca2+ transport decreases with aging. Oxidative stress inhibits the intestinal Ca2+ absorption whereas the antioxidants counteract the effects of prooxidants leading to the normalization of this physiological process. Several pathologies such as celiac disease, inflammatory bowel diseases, Turner syndrome and others occur with inhibition of intestinal Ca2+ absorption, some hypercalciurias show Ca2+ hyperabsorption, most of these alterations are related to the vitamin D endocrine system. Further research work should be accomplished in order not only to know more molecular details but also to detect possible therapeutic targets to ameliorate or avoid the consequences of altered intestinal Ca2+ absorption.

Natural Product-Based Nanomedicine in Treatment of Inflammatory Bowel Disease

: Many synthetic drugs and monoclonal antibodies are currently in use to treat Inflammatory Bowel Disease (IBD). However, they all are implicated in causing severe side effects and long-term use results in many complications. Numerous in vitro and in vivo experiments demonstrate that phytochemicals and natural macromolecules from plants and animals reduce IBD-related complications with encouraging results. Additionally, many of them modify enzymatic activity, alleviate oxidative stress, and downregulate pro-inflammatory transcriptional factors and cytokine secretion. Translational significance of natural nanomedicine and strategies to investigate future natural product-based nanomedicine is discussed. Our focus in this review is to summarize the use of phytochemicals and macromolecules encapsulated in nanoparticles for the treatment of IBD and IBD-associated colorectal cancer.

Quercetin Suppresses AOM/DSS-Induced Colon Carcinogenesis through Its Anti-Inflammation Effects in Mice

Colorectal cancer (CRC) is the fourth leading cause of tumor-related deaths worldwide. In this study, we explored the in vivo effects of quercetin, a plant flavonol from the flavonoid group of polyphenols with antioxidant effects, on colon carcinogenesis induced by azoxymethane/dextran sodium sulfate (AOM/DSS). Thirty mice were randomly assigned into three groups: the control group, the AOM/DSS group, and the quercetin+AOM/DSS group. CRC was induced by AOM injection and a solution of 2% DSS in the drinking water. In the AOM/DSS-induced colon cancer mice model, quercetin treatment dramatically reduced the number and size of colon tumors. In addition, quercetin significantly restored the leukocyte counts by decreasing the inflammation caused by AOM/DSS. We also observed that the expression of oxidative stress markers, such as lipid peroxide (LPO), nitric oxide (NO), superoxide dismutase (SOD), glucose-6-phosphate (G6PD), and glutathione (GSH), could be reduced by quercetin, suggesting that the anti-inflammatory function of quercetin comes from its antioxidant effect. Moreover, potential biomarkers were identified with serum metabolite profiling. Increased levels of 2-hydroxybutyrate, 2-aminobutyrate, and 2-oxobutyrate and decreased levels of gentian violet, indole-3-methyl acetate, N-acetyl-5-hydroxytryptamine, indoxyl sulfate, and indoxyl were also found in the AOM/DSS-treated mice. However, quercetin treatment successfully decreased the levels of 2-hydroxybutyrate, 2-aminobutyrate, 2-oxobutyrate, endocannabinoids, and sphinganine and increased the levels of gentian violet, N-acetyl-5-hydroxytryptamine, indoxyl sulfate, and indoxyl. Together, our data demonstrated that quercetin could maintain relatively potent antitumor activities against colorectal cancer in vivo through its anti-inflammation effect.

Protective effect of quercetin on streptozotocin-induced diabetic peripheral neuropathy rats through modulating gut microbiota and reactive oxygen species level

OBJECTIVE

Diabetic peripheral neuropathy (DPN) is a prevalent complication of diabetes with no effective drug currently. As a powerful antioxidant, the flavonoid quercetin has been demonstrated to have potential neuroprotective and prebiotic capacity. But the mechanism of its neuroprotective function and the link to the gut microbiota remains to be elucidated.

METHODS

The neuroprotective effect of quercetin was evaluated on streptozotocin(STZ)-induced DPN rats through electrophysiology, behavioristic, and pathomorphology studies. Serum and urine reactive oxygen species (ROS) production levels and fecal gut microbiota compositions were detected, and the relationship between them was analyzed by Spearman's correlation.

RESULTS

Quercetin not only reversed the decreased mechanical withdraw thresholds and intraepidermal nerve fiber densities in DPN rats, but also improved neurological morphology of sciatic nerves, accompanied with up-regulated percentage of paranodes at paranodal junctions, and down-regulated amyloid precursor protein and ionized calcium-binding adaptor molecule 1 in DPN rats. More importantly, quercetin rescued gut dysbiosis in DPN rats by decreasing four potential pathogenic species and enriching two prebiotic species associated with DPN phenotypes and ROS production levels.

CONCLUSIONS

Quercetin exerts neuroprotective effect and modulates gut microbiota associated with DPN phenotypes and ROS production levels in STZ-induced DPN rats, suggesting the therapeutic application of quercetin for DPN prevention and treatment.

Quercetin Alleviates Intestinal Oxidative Damage Induced by H2O2 via Modulation of GSH: In Vitro Screening and In Vivo Evaluation in a Colitis Model of Mice

The gastrointestinal tract is exposed to pro-oxidants from food, host immune factors, and microbial pathogens, which may induce oxidative damage. Oxidative stress has been shown to play an important role in the onset of inflammatory bowel disease. This study aimed to use a novel model to evaluate the effects of a screened natural component and explore its possible mechanism. An in vitro oxidative stress Caco2 cell model induced by H₂O₂ was established using a real-time cellular analysis system and verified by addition of glutathione (GSH). A variety of plant components were chosen for the screening. Quercetin was the most effective phytochemical to alleviate the decreased cell index caused by H₂O₂ among the tested plant components. Furthermore, quercetin ameliorated dextran sulfate sodium salt (DSS)-induced colitis and further increased the serum GSH. The mechanism of quercetin protection was explored in Caco2. Reversed H₂O₂-induced cell damage and decreased reactive oxygen species and apoptosis ratio were observed in quercetin-treated cells. Also, quercetin increased expression of the glutamate-cysteine ligase catalytic subunit (GCLC), the first rate-limiting enzyme of glutathione synthesis, and increased intracellular GSH concentration under H₂O₂ treatment. This effect was abolished by the GCLC inhibitor buthionine sulfoximine. These results indicated that quercetin can improve cell proliferation and increase intracellular GSH concentrations by upregulating transcription of GCLC to eliminate excessive reactive oxygen species (ROS). Increased extracellular H₂O₂ concentration induced by quercetin under oxidative stress was related to the inhibition of AQP3 and upregulation of NOX1/2, which may contribute to the observed protective effects of quercetin. Moreover, the novel H₂O₂-induced oxidative stress cell model based on the real-time cellular analysis system was an effective model to screen natural products to deal with intestinal oxidative damage and help accelerate the discovery of new drugs for inflammatory bowel disease (IBD).

Gostner J, Kurz K. Pharmacological Targets of Kaempferol Within Inflammatory Pathways-A Hint Towards the Central Role of Tryptophan Metabolism

The flavonoid kaempferol is almost ubiquitously contained in edible and medicinal plants and exerts a broad range of interesting pharmacological activities. Interactions with central inflammatory processes can be exploited to treat or attenuate symptoms of disorders associated with chronic immune activation during infections, malignancies, and neurodegenerative or cardiovascular disorders. Many drugs, phytochemicals, and nutritional components target the catabolism of the essential amino acid tryptophan by indoleamine 2,3-dioxygenase 1 (IDO-1) for immunomodulation. We studied the effects of kaempferol by in vitro models with human peripheral blood mononuclear cells (PBMC) and THP-1 derived human myelomonocytic cell lines. Kaempferol suppressed interferon-γ dependent immunometabolic pathways: Formation of the oxidative stress biomarker neopterin and catabolism of tryptophan were inhibited dose-dependently in stimulated cells. In-silico docking studies revealed a potential interaction of kaempferol with the catalytic domain of IDO-1. Kaempferol stimulated nuclear factor kappa B (NF-κB) signaling in lipopolysaccharide (LPS)-treated THP-1 cells, thereby increasing the mRNA expression of interleukin (IL) 1 beta, tumor necrosis factor, and nuclear factor kappa B subunit 1, while IL6 was downregulated. Data suggest that concerted effects of kaempferol on multiple immunologically relevant targets are responsible for its immunomodulatory activity. However, the immunosuppressive effects may be more relevant in a T-cell dominated context.

Modulation of inflammatory response and gut microbiota in ankylosing spondylitis mouse model by bioactive peptide IQW

AIMS

Ankylosing spondylitis (AS) is a widespread and chronic inflammatory autoimmune disease of unknown provenance. Naturally occurring peptides and proteins have shown significant promise as modulators of immune responses. Thus, the aims of this study were to assess the protective effects of the bioactive peptide IQW (Ile-Gln-Trp) with respect to inflammatory indicators, gut microbiota and oxidative stress, and to examine the potential mechanisms of these effects.

METHODS AND RESULTS

A mouse model was prepared by four injections of human proteoglycan extract (2 mg) in dimethyldioctadecylammonium solution (2 mg) over an interval of 2 weeks. Enzyme-linked immunosorbent assay results for the markers of oxidative stress and inflammation in the AS mice revealed increased concentrations of malondialdehyde, IL-6, IL-1β and TNF-α, along with decreased concentrations of catalase (CAT), glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD). Treatment with IQW was found to decrease the concentrations of IL-6, IL-1β and TNF-α, and increase the concentrations of CAT, GSH-PX and SOD. Moreover the quantification of the microbiota via 16s rRNA sequencing revealed a reduced microbial diversity in the AS mice, while a significantly increased microbial diversity was displayed by those treated with IQW. Whereas, there was a significant reduction in the relative abundance of Bacteroidetes and an increased relative abundance of Verrucomicrobia in AS mice, this was reversed following the IQW treatment.

CONCLUSIONS

The results demonstrated that IQW exerts a beneficial influence in AS by delaying progression of the disease, reducing the arthritic grade of intervertebral joints, altering the concentrations of cytokines and modulating the microbial diversity and composition.

SIGNIFICANCE AND IMPACT OF THE STUDY

Oral IQW treatment might represent a new approach to mitigate the onset and development of AS.

Quercetin reduces atherosclerotic lesions by altering the gut microbiota and reducing atherogenic lipid metabolites

AIMS

Epidemiological studies have correlated cardiovascular disease and atherosclerosis with lifestyle factors such as sedentary behaviour and a high-calorie diet. Recent studies of pathogenesis have highlighted the significance of the intestinal microbiota and chronic inflammation with respect to both the onset and development of atherosclerosis. This study examined the hypothesis that the oral administration of quercetin to low-density lipoprotein receptor-null (Ldlr^-/- ) mice would improve gut health by altering the gut microbiota and controlling the levels of atherogenic lipid metabolites and proinflammatory mediators in the intestine and serum.

METHODS AND RESULTS

Mice were maintained on a high-fat diet with or without oral quercetin administration for 12 weeks. Quercetin treatment suppressed body weight gains and reduced the extent of atherosclerotic lesions in the aortic sinus. Reduced malondialdehyde and increased interleukin 6 levels further indicated the protective effect of quercetin against immune/inflammatory responses and oxidative stress. Furthermore, quercetin led to decreased intestinal levels of cholesterol, lysophosphatidic acids and atherogenic lysophosphatidylcholine (LPC 18:1) and an increased level of coprostanol. A phylum-level microbial analysis revealed that quercetin treatment reduced the abundance of Verrocomicrobia and increased microbiome diversity and the abundances of Actinobacteria, Cyanobacteria and Firmicutes. A Spearman analysis revealed negative correlations of Actinobacteria with intestinal and plasma LPC 18:1 and caecal cholesterol levels and of Firmicutes and Cyanobacteria with the plasma LPC 18:1 level.

CONCLUSIONS

This study demonstrated the ability of quercetin treatment to reduce lipid levels, as well as the areas of atherosclerotic lesions and sizes of plaques. This treatment also altered the composition of the gut microbiota and decreased the levels of atherogenic lipid metabolites.

SIGNIFICANCE AND IMPACT OF THE STUDY

Oral quercetin treatment may represent a new approach to mitigating the onset and development of atherosclerosis.

The Effect of Dietary Quercetin on the Glutathione Redox System and Small Intestinal Functionality of Weaned Piglets

Quercetin has been shown to alleviate mucosal damage and modulate the glutathione (GSH) redox system in the colon of rodents. In the current study, we assessed whether quercetin was able to mitigate small intestinal dysfunction in weaned pigs. Here, 224 weaned piglets were fed a diet containing quercetin at either 0, 100, 300, or 900 mg/kg diet until d14 post-weaning, followed by a common basal diet until d42. Eight animals per treatment were sampled at d5 and d14 post-weaning. In these animals, the small intestinal histomorphology, barrier function, and protein abundance of occludin, caspase-3, and proliferating cell nuclear antigen were assessed. None of these parameters were affected, and neither did quercetin improve performance up to d42 post-weaning. The GSH redox system was evaluated in blood, small intestinal mucosa, and liver. Quercetin did not affect the glutathione peroxidase, glutathione reductase, and glutamate–cysteine ligase activity in these tissues. In contrast, the hepatic glutathione transferase (GST) activity was significantly increased by quercetin supplementation at d5 post-weaning of 100, 300, and 900 mg/kg. Importantly, d5 was characterized by a more oxidized GSH redox status. To conclude, dietary quercetin had little effect on the small intestine, but did upregulate hepatic GST in the occurrence of redox disturbance.

Dietary Quercetin Increases Colonic Microbial Diversity and Attenuates Colitis Severity in Citrobacter rodentium-Infected Mice

Disturbed balance between microbiota, epithelial cells, and resident immune cells within the intestine contributes to inflammatory bowel disease (IBD) pathogenesis. The Citrobacter rodentium-induced colitis mouse model has been well documented. This model allows the analysis of host responses to enteric bacteria and facilitates improved understanding of the potential mechanisms of IBD pathogenesis. The current study evaluated the effects of dietary 30 mg/kg quercetin supplementation on C. rodentium-induced experimental colitis in C57BL/6 mice. Following dietary quercetin supplementation, the mice were infected with 5 × 10⁸ CFU C. rodentium, and the pathological effects of C. rodentium were measured. The results showed that quercetin alleviated the effects of C. rodentium-induced colitis, suppressed the production of pro-inflammatory cytokines, such as interleukin (IL)-17, tumor necrosis factor alpha, and IL-6 (p < 0.05), and promoted the production of IL-10 in the colon tissues (p < 0.05). Quercetin supplementation also enhanced the populations of Bacteroides, Bifidobacterium, Lactobacillus, and Clostridia and significantly reduced those of Fusobacterium and Enterococcus (p < 0.05). These findings indicate that dietary quercetin exerts therapeutic effects on C. rodentium-induced colitis, probably due to quercetin’s ability to suppress pro-inflammatory cytokines and/or modify gut microbiota. Thus, these results suggest that quercetin supplementation is effective in controlling C. rodentium-induced inflammation.

Biological Effects and Applications of Chitosan and Chito-Oligosaccharides

The numerous functional properties and biological effects of chitosan and chito-oligosaccharides (COS) have led to a significant level of interest, particularly with regard to their potential use in the agricultural, environmental, nutritional, and pharmaceutical fields. This review covers recent studies on the biological functions of COS and the impacts of dietary chitosan and COS on metabolism. The majority of results suggest that the use of chitosan as a feed additive has favorable biological effects, such as antimicrobial, anti-oxidative, cholesterol reducing, and immunomodulatory effects. The biological impacts reviewed herein may provide a new appreciation for the future use of COS.

The Bidirectional Interactions between Resveratrol and Gut Microbiota: An Insight into Oxidative Stress and Inflammatory Bowel Disease Therapy

Dysbiosis and oxidative stress in the gut have contributed to the progression of intestinal inflammatory bowel disease (IBD). The current study has reported that enteric bacteria mediate redox homeostasis through the regulation of reactive oxygen species (ROS) production. Resveratrol, one of the most abundant polyphenols, with poor oral bioavailability, is considered as a scavenger of ROS and other free radicals. Recent studies have shown that resveratrol effectively enhances the growth of Lactococcus lactis and inhibits the growth of Enterococcus faecalis. (1) In terms of the two-way relationship between gut microbiota and resveratrol, resveratrol modulates gut microbiota; (2) in terms of resveratrol biotransformation by gut microbiota, we speculate that gut microbiota could be a target of resveratrol to maintain gut homeostasis. Here, we reviewed the current researches about the cellular signaling pathways in intestinal epithelial cells triggered by gut microbiota in response to oxidative stress. These results suggest that the modulation of the gut microbiota through resveratrol supplementation appears as a promising potential approach for the therapy of inflammatory bowel disease.

Egg Protein Transferrin-Derived Peptides IRW and IQW Regulate Citrobacter rodentium-Induced, Inflammation-Related Microbial and Metabolomic Profiles

Bioactive peptides that target the gastrointestinal tract can strongly affect the health of animals and humans. This study aimed to evaluate the abilities of two peptides derived from egg albumin transferrin, IRW and IQW, to treat enteritis in a mouse model of Citrobacter rodentium-induced colitis by evaluating serum metabolomics and gut microbes. Forty-eight mice were randomly assigned to six groups: basal diet (CTRL), intragastric administration Citrobacter rodentium (CR), basal diet with 0.03%IRW (IRW), CR with 0.03% IRW (IRW+CR), basal diet with 0.03%IQW (IQW) and CR with 0.03% IQW (IQW+CR). CR administration began on day 10 and continued for 7 days. After 14 days of IRW and IQW treatment, serum was collected and subjected to a metabolomics analysis. The length and weight of each colon were measured, and the colon contents were collected for 16srRNA sequencing. The colons were significantly longer in the CR group, compared to the CTRL group. A serum metabolomics analysis revealed no significant difference in microbial diversity between the six groups. Compared with the CTRL group, the proportions of Firmicutes and Actinobacteria species decreased significantly and the proportions of Bacteroidetes and Proteobacteria species increased in the CR group. There were no significant differences between the CTRL and other groups. The serum metabolomics analysis revealed that Infected by CR increased the levels of oxalic acid, homogentisic acid and prostaglandin but decreased the levels of L-glutamine, L-acetyl carnitine, 1-methylhistidine and gentisic acid. Therefore, treatment with IRW and IQW was shown to regulate the intestinal microorganisms associated with colonic inflammation and serum metabolite levels, thus improving intestinal health.