Flavonoids and the gastrointestinal tract: Local and systemic effects

Influence of Tilia tomentosa Moench Extract on Mouse Small Intestine Neuromuscular Contractility

Functional gastrointestinal disorders (FGIDs) are characterized by abdominal pain, bloating and bowel disturbances. FGID therapy is primarily symptomatic, including treatment with herbal remedies. Flower extract of Tilia tomentosa Moench (TtM) is occasionally used as an anti-spasmodic in popular medicine. Since its effect on intestinal response is unknown, we evaluated the influence of TtM extract on small intestine contractility. Ileal preparations from C57BL/6J mice were mounted in organ baths to assess changes in muscle tension, following addition of TtM extract (0.5–36 μg/mL) or a vehicle (ethanol). Changes in contractile response to receptor- and non-receptor-mediated stimuli were assessed in ileal preparations pretreated with 12 μg/mL TtM. Alterations in the enteric nervous system neuroglial network were analyzed by confocal immunofluorescence. Increasing addition of TtM induced a marked relaxation in ileal specimens compared to the vehicle. Pretreatment with TtM affected cholinergic and tachykininergic neuromuscular contractions as well as K⁺-induced smooth muscle depolarization. Following incubation with TtM, a significant reduction in non-adrenergic non-cholinergic-mediated relaxation sensitive to Nω-Nitro-L-arginine methyl ester hydrochloride (pan-nitric oxide synthase inhibitor) was found. In vitro incubation of intestinal specimens with TtM did not affect the myenteric plexus neuroglial network. Our findings show that TtM-induced intestinal relaxation is mediated by nitric oxide pathways, providing a pharmacological basis for the use of TtM in FGIDs.

Multi-omics reveals the positive leverage of plant secondary metabolites on the gut microbiota in a non-model mammal

BACKGROUND

Flavonoids are important plant secondary metabolites (PSMs) that have been widely used for their health-promoting effects. However, little is known about overall flavonoid metabolism and the interactive effects between flavonoids and the gut microbiota. The flavonoid-rich bamboo and the giant panda provide an ideal system to bridge this gap.

RESULTS

Here, integrating metabolomic and metagenomic approaches, and in vitro culture experiment, we identified 97 flavonoids in bamboo and most of them have not been identified previously; the utilization of more than 70% flavonoid monomers was attributed to gut microbiota; the variation of flavonoid in bamboo leaves and shoots shaped the seasonal microbial fluctuation. The greater the flavonoid content in the diet was, the lower microbial diversity and virulence factor, but the more cellulose-degrading species.

CONCLUSIONS

Our study shows an unprecedented landscape of beneficial PSMs in a non-model mammal and reveals that PSMs remodel the gut microbiota conferring host adaptation to diet transition in an ecological context, providing a novel insight into host-microbe interaction. Video abstract.

Fungal Biotransformation of 2'-Methylflavanone and 2'-Methylflavone as a Method to Obtain Glycosylated Derivatives

Methylated flavonoids are promising pharmaceutical agents due to their improved metabolic stability and increased activity compared to unmethylated forms. The biotransformation in cultures of entomopathogenic filamentous fungi is a valuable method to obtain glycosylated flavones and flavanones with increased aqueous solubility and bioavailability. In the present study, we combined chemical synthesis and biotransformation to obtain methylated and glycosylated flavonoid derivatives. In the first step, we synthesized 2'-methylflavanone and 2'-methylflavone. Afterwards, both compounds were biotransformed in the cultures of two strains of entomopathogenic filamentous fungi Beauveria bassiana KCH J1.5 and Isaria fumosorosea KCH J2. We determined the structures of biotransformation products based on NMR spectroscopy. Biotransformations of 2'-methyflavanone in the culture of B. bassiana KCH J1.5 resulted in three glycosylated flavanones: 2'-methylflavanone 6-O-β-d-(4″-O-methyl)-glucopyranoside, 3'-hydroxy-2'-methylflavanone 6-O-β-d-(4″-O-methyl)-glucopyranoside, and 2-(2'-methylphenyl)-chromane 4-O-β-d-(4″-O-methyl)-glucopyranoside, whereas in the culture of I. fumosorosea KCH J2, two other products were obtained: 2'-methylflavanone 3'-O-β-d-(4″-O-methyl)-glucopyranoside and 2-methylbenzoic acid 4-O-β-d-(4'-O-methyl)-glucopyranoside. 2'-Methylflavone was effectively biotransformed only by I. fumosorosea KCH J2 into three derivatives: 2'-methylflavone 3'-O-β-d-(4″-O-methyl)-glucopyranoside, 2'-methylflavone 4'-O-β-d-(4″-O-methyl)-glucopyranoside, and 2'-methylflavone 5'-O-β-d-(4″-O-methyl)-glucopyranoside. All obtained glycosylated flavonoids have not been described in the literature until now and need further research on their biological activity and pharmacological efficacy as potential drugs.

Comparison of Antioxidant Properties of a Conjugate of Taxifolin with Glyoxylic Acid and Selected Flavonoids

It is known that flavonoids can react with toxic carbonyl compounds in the process of the storage, aging, and digestion of flavonoid-rich foods and beverages. However, the effect of these reactions on the antioxidant properties of the polyphenolic fraction and the properties of the resulting products remain poorly studied. The aim of the present work was to study the antioxidant activity of quercetin, taxifolin, catechin, eriodictyol, hesperetin, naringenin and a product of the condensation of taxifolin with glyoxylic acid, as well as to reveal the structure–activity relationship of these polyphenols. It was found that flavonoids containing the catechol moiety exhibited higher antioxidant activity than hesperetin and naringenin. The product showed the highest hydrogen peroxide scavenging activity, a lower metal-reducing and a higher iron-binding ability than catechol-containing flavonoids, and a lipid peroxidation inhibitory activity comparable with that of taxifolin. Thus, the condensation of flavonoids with toxic carbonyl compounds might lead to the formation of products exhibiting high antioxidant activity. Meanwhile, the conditions under which parent flavonoids and their products exhibit the maximal antioxidant activity may differ. The data suggest that the antioxidant profile of the polyphenolic fraction and bioavailability of polyphenols, carbonyl compounds, and metal ions may change when these reactions occur.

Silk fibroin nanoparticles enhance quercetin immunomodulatory properties in DSS-induced mouse colitis

Inflammatory bowel disease (IBD) is a chronic and idiopathic inflammatory disorder affecting the gastrointestinal tract. The pharmacological treatments used currently for its treatment lack efficacy, so new therapeutic strategies should be developed. In this context, flavonoids loaded in biopolymeric nanoparticles can be considered as novel promising candidates. The aim of the present study was to evaluate the intestinal anti-inflammatory effects of quercetin when is administered loaded in silk fibroin nanoparticles (QSFN) in the dextran sulphate sodium experimental model of mouse colitis, which displays some similarities to human IBD. Previously characterized quercetin-loaded silk fibroin nanoparticles (QSFN). QSFN showed a reversible aggregation profile induced by the acidification of the solution but did not affect the loaded quercetin. Daily administration of QSFN significantly reduced disease activity index values compared to the control colitic group. This beneficial effect was not only corroborated by the histological examination of the colonic specimens but also the improvement of the colonic expression of the different proinflammatory cytokines (Tnf-α, Il-1β, Il-6, Mcp-1, Icam-1, Nlrp3 and iNOS). Therefore, these data suggest that QSFN could be a promising alternative to current treatments as a drug delivery system for IBD treatment.

Enhancement of bioavailability and bioactivity of diet-derived flavonoids by application of nanotechnology: a review

Flavonoids, which are a class of polyphenols widely existing in food and medicine, have enormous pharmacological effects. The functional properties of flavonoids are mainly distributed to their anti-oxidative, anticancer, and anti-inflammatoryeffects, etc. However, flavonoids' low bioavailability limits their clinical application, which is closely related to their intestinal absorption and metabolism. In addition, because of the short residence time of oral bioactive molecules in the stomach, low permeability and low solubility in the gastrointestinal tract, flavonoids are easy to be decomposed by the external environment and gastrointestinal tract after digestion. To tackle these obstacles, technological approaches like microencapsulation have been developed and applied for the formulation of flavonoid-enriched food products. In the light of these scientific advances, the objective of this review is to establish the structural requirements of flavonoids for appreciable anticancer, anti-inflammatory, and antioxidant effects, and elucidate a comprehensive mechanism that can explain their activity. Furthermore, the novelty in application of nanotechnology for the safe delivery of flavonoids in food matrices is discussed. After a literature on the flavonoids and their health attributes, the encapsulation methods and the coating materials are presented.

Polyphenols and Visual Health: Potential Effects on Degenerative Retinal Diseases

Dietary polyphenols are a group of natural compounds that have been proposed to have beneficial effects on human health. They were first known for their antioxidant properties, but several studies over the years have shown that these compounds can exert protective effects against chronic diseases. Nonetheless, the mechanisms underlying these potential benefits are still uncertain and contradictory effects have been reported. In this review, we analyze the potential effects of polyphenol compounds on some visual diseases, with a special focus on retinal degenerative diseases. Current effective therapies for the treatment of such retinal diseases are lacking and new strategies need to be developed. For this reason, there is currently a renewed interest in finding novel ligands (or known ligands with previously unexpected features) that could bind to retinal photoreceptors and modulate their molecular properties. Some polyphenols, especially flavonoids (e.g., quercetin and tannic acid), could attenuate light-induced receptor damage and promote visual health benefits. Recent evidence suggests that certain flavonoids could help stabilize the correctly folded conformation of the visual photoreceptor protein rhodopsin and offset the deleterious effect of retinitis pigmentosa mutations. In this regard, certain polyphenols, like the flavonoids mentioned before, have been shown to improve the stability, expression, regeneration and folding of rhodopsin mutants in experimental in vitro studies. Moreover, these compounds appear to improve the integration of the receptor into the cell membrane while acting against oxidative stress at the same time. We anticipate that polyphenol compounds can be used to target visual photoreceptor proteins, such as rhodopsin, in a way that has only been recently proposed and that these can be used in novel approaches for the treatment of retinal degenerative diseases like retinitis pigmentosa; however, studies in this field are limited and further research is needed in order to properly characterize the effects of these compounds on retinal degenerative diseases through the proposed mechanisms.

Absorption, metabolism and bioavailability of flavonoids: a review

Flavonoids are stored in various plants and widely presented in different kinds of food in variable amounts. Plant roots, stems, leaves, flowers and fruits are known to have high amounts of flavonoids. However, flavonoid aglycones are found less frequently in natural products, as it requires bioconversion through bacteria, which provide β-glucosidase to convert them. Recently, flavonoids and its metabolites were applied in the prevention and treatment of various diseases such as cancers, obesity, diabetes, hypertension, hyperlipidemia, cardiovascular diseases, neurological disorders and osteoporosis in numerous studies. This review focused on absorption, activity, metabolism, and bioavailability of flavonoids. Also authors organized and collected newly-found reports of flavonoids and their absorption barriers of flavonoids in the gastrointestinal tract, providing the latest findings and evidence from the past decade. Particularly, nanoparticles delivery systems are emphasized regarding fabrication methods and their potential benefits on flavonoids. Moreover, the potential challenges of nanoparticles as delivery system for flavonoids in the gastrointestinal tract are also discussed.

Regulation of Cytochrome c Oxidase by Natural Compounds Resveratrol, (-)-Epicatechin, and Betaine

Numerous naturally occurring molecules have been studied for their beneficial health effects. Many compounds have received considerable attention for their potential medical uses. Among them, several substances have been found to improve mitochondrial function. This review focuses on resveratrol, (–)-epicatechin, and betaine and summarizes the published data pertaining to their effects on cytochrome c oxidase (COX) which is the terminal enzyme of the mitochondrial electron transport chain and is considered to play an important role in the regulation of mitochondrial respiration. In a variety of experimental model systems, these compounds have been shown to improve mitochondrial biogenesis in addition to increased COX amount and/or its enzymatic activity. Given that they are inexpensive, safe in a wide range of concentrations, and effectively improve mitochondrial and COX function, these compounds could be attractive enough for possible therapeutic or health improvement strategies.

Total Flavonoids of Glycyrrhiza uralensis Alleviates Irinotecan-Induced Colitis via Modification of Gut Microbiota and Fecal Metabolism

Irinotecan (CPT-11)-induced gastrointestinal toxicity strongly limits its anticancer efficacy. Glycyrrhiza uralensis Fisch., especially flavonoids, has strong anti-inflammatory and immunomodulatory activities. Herein, we investigate the protective effect of the total flavonoids of G. uralensis (TFGU) on CPT-11-induced colitis mice from the perspective of gut microbiota and fecal metabolism. The body weight and colon length of mice were measured. Our results showed that oral administration of TFGU significantly attenuated the loss of body weight and the shortening of colon length induced by CPT-11. The elevated disease activity index and histological score of colon as well as the up-regulated mRNA and protein levels of TNF-α, IL-1β, and IL-6 in the colonic tissue of CPT-11-treated mice were significantly decreased by TFGU. Meanwhile, TFGU restored the perturbed gut microbial structure and function in CPT-11-treated mice to near normal level. TFGU also effectively reversed the CPT-11-induced fecal metabolic disorders in mice, mainly call backing the hypoxanthine and uric acid in purine metabolism. Spearman's correlation analysis further revealed that Lactobacillus abundance negatively correlated with fecal uric acid concentration, suggesting the pivotal role of gut microbiota in CPT-11-induced colitis. Since uric acid is a ligand of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, TFGU was further validated to inhibit the activation of NLRP3 inflammasome by CPT-11. Our findings suggest TFGU can correct the overall gut microbial dysbiosis and fecal metabolic disorders in the CPT-11-induced colitis mice, underscoring the potential of using dietary G. uralensis as a chemotherapeutic adjuvant.

Four Citrus Flavanones Exert Atherosclerosis Alleviation Effects in ApoE-/- Mice via Different Metabolic and Signaling Pathways

Citrus flavanones have the potential to alleviate atherosclerosis. The metabolism and anti-atherosclerosis signaling pathways of four citrus flavanones (naringin, naringenin, hesperidin, and hesperetin) were compared in ApoE^-/- mice. Naringin had the most potent anti-atherogenic effect, followed by hesperidin, naringenin, and hesperetin with reductions of 55.92, 34.98, 42.87, and 24.70% in the atherosclerotic plaque rate compared with the control, respectively. Oral naringin mainly existed in the intestine due to the high water solubility of 7-O-nohesperidoside and alleviated atherosclerosis mainly by enhancing bile acid synthesis in the gut microbiota-FXR/FGF15-CYP7A1 pathway. The other three flavanones mainly alleviated atherosclerosis in the liver after absorption from the intestine. Hesperidin upregulates ABCA1 by 1.8-fold to enhance cholesterol reverse transport, while the aglycones naringenin and hesperetin inhibited cholesterol synthesis via downregulating HMGCR by 2.4- and 2.3-fold, respectively. Hesperetin was more resistant to absorption than naringenin due to the existence of a 4'-methoxyl group and had relatively weak effects on atherosclerosis. The alleviation of atherosclerosis by the four citrus flavanones was tightly related to differences in their in vivo metabolism and signaling pathways. This provides new insights into the anti-atherosclerotic mechanisms of food functional flavanones and guidance for the design of novel, efficient strategies for preventing atherosclerosis based on citrus flavanones.

The role and mechanism of citrus flavonoids in cardiovascular diseases prevention and treatment

Cardiovascular diseases (CVDs) have been ranked as the leading cause of death in the world, whose global incidence is increasing year by year. Citrus, one of the most popular fruits in the world, is rich in flavonoids. Citrus flavonoids attract special attention due to a variety of biological activities, especially in the prevention and treatment of CVDs. The research progress of citrus flavonoids on CVDs have been constantly updated, but relatively fragmented, which needed to be systematically summarized. Hence, the recent research about citrus flavonoids and CVDs were reviewed, including the types and in vivo processes of citrus flavonoids, epidemiology study and mechanism on prevention and treatment of CVDs by citrus flavonoids. This review would provide a theoretical basis for the citrus flavonoids research and a new idea in the citrus industry development and application.

Reparative Effects of Ethanol-Induced Intestinal Barrier Injury by Flavonoid Luteolin via MAPK/NF-κB/MLCK and Nrf2 Signaling Pathways

Luteolin, a dietary flavonoid, has gained increasing interest as an intestinal protectant. This study aimed to evaluate the reparative effect of luteolin against ethanol-induced intestinal barrier damage in a Caco-2 cell monolayer model and the potential mechanisms. Luteolin attenuated ethanol-induced intestinal barrier injury, by increasing transepithelial monolayer resistance (TEER, 27.75 ± 14.75% of the ethanol group, p < 0.01), reducing Lucifer yellow flux (13.21 ± 1.23% of ethanol group, p < 0.01), and upregulating the expression of tight junction (TJ) proteins zonulin occludin-1 (ZO-1), occludin, and claudin-1 (37.963 ± 8.62%, 17.69 ± 7.35%, and 29.40 ± 8.08% of the ethanol group, respectively, p < 0.01). Further mechanistic studies showed that luteolin suppressed myosin light chain 2 (MLC) phosphorylation, myosin light chain kinase (MLCK) activation, nuclear factor kappa-B (NF-κB) nuclear translocation, and mitogen-activated-protein-kinase (MAPK) phosphorylation. Moreover, luteolin also acted as antioxidants indirectly by upregulating antioxidant-responsive-element (ARE) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) nuclear translocation to relieve ethanol-induced oxidative damage and TJ dysfunction. The results of the study indicate that luteolin may play an effective role in relieving intestinal barrier damage, and this effect is at least partially due to its indirect antioxidant capacity.

The fate of flavonoids after oral administration: a comprehensive overview of its bioavailability

Despite advancements in synthetic chemistry, nature remains the primary source of drug discovery, and this never-ending task of finding novel and active drug molecules will continue. Flavonoids have been shown to possess highly significant therapeutic activities such as anti-inflammatory, anti-oxidant, anti-viral, anti-diabetic, anti-cancer, anti-aging, neuroprotective, and cardioprotective, etc., However, it has been found that orally administered flavonoids have a critical absorption disorder and, therefore, have low bioavailability and show fluctuating pharmacokinetic and pharmacodynamic responses. A detailed investigation is required to assess and analyze the variation in the bioavailability of flavonoids due to interactions with the intestinal barrier. This review will emphasize on the bioavailability and the pharmacological applications of flavonoids, key factors affecting their bioavailability, and strategies for enhancing bioavailability, which may lead to deeper understanding of the extent of flavonoids as a treatment and/or prevention for different diseases in clinics.

Changes in rainbow trout (Oncorhynchus mykiss) growth and mucosal immune parameters after dietary administration of grape (Vitis vinifera) seed extract

The effect of dietary grape (Vitis vinifera) seed extract (GSE) on growth performance and mucosal immune parameters in rainbow trout (Oncorhynchus mykiss) fry was studied. Fish (1.3 g mean weight) were randomly distributed in nine tanks (15 fish per tank) and fed diets containing GSE at 0 (control), 100, and 200 mg kg^-1for 60 days. The results showed that growth parameters were enhanced in both treatment groups compared to the control group. Histological examination of fish skin showed higher epidermis thickness, goblet cell density, and volume density in the GSE groups compared to the values of the control group. Furthermore, the villus height, goblet cell density, and intraepithelial lymphocytes were increased in the fish intestine in those fish fed GSE, with respect to control fish. Feeding fish with low dose of GSE (100 mg kg^-1) up-regulated the expression of some immune-relevant genes, including complement component 3 (C3), lysozyme (Lys), omDB-3, interferon gamma (IFN-γ), and tumor necrosis factor-α (TNF-α) in different mucosal tissues. However, feeding fish the high dose of GSE (200 mg kg^-1) mostly enhanced expression of these genes in the skin. Besides, skin mucus of fish fed GSE showed bactericidal activity against Yersinia ruckeri. It was concluded that GSE, especially at 100 mg kg^-1, modulates the growth performance and mucosal immunity of rainbow trout.

Flavonoids: structure-function and mechanisms of action and opportunities for drug development

Flavonoids are polyphenolic phytochemicals produced in fruits, nuts and vegetables and dietary consumption of these structurally diverse compounds is associated with multiple health benefits including increased lifespan, decreased cardiovascular problems and low rates of metabolic diseases. Preclinical studies with individual flavonoids demonstrate that these compounds exhibit anti-inflammatory and anticancer activities and they enhance the immune system. Their effectiveness in both chemoprevention and chemotherapy is associated with their targeting of multiple genes/pathways including nuclear receptors, the aryl hydrocarbon receptor (AhR), kinases, receptor tyrosine kinases and G protein-coupled receptors. However, despite the remarkable preclinical activities of flavonoids, their clinical applications have been limited and this is due, in part, to problems in drug delivery and poor bioavailability and these problems are being addressed. Further improvements that will expand clinical applications of flavonoids include mechanism-based precision medicine approaches which will identify critical mechanisms of action of individual flavonoids with optimal activities that can be used in combination therapies.

The biological fate and bioefficacy of citrus flavonoids: bioavailability, biotransformation, and delivery systems

Citrus fruits are among the most popularly consumed fruits worldwide, including oranges, grapefruits, pomelos and lemons. Citrus flavonoids such as hesperidin, naringin and nobiletin have shown an array of health benefits in cell, animal and clinical studies, including antioxidative, anti-inflammatory, neuroprotective, anticancer, and anti-obesity activities. Citrus flavonoids have limited bioavailability after oral administration, leaving the major part unabsorbed and persisted in the colon. Recent studies have highlighted the important role of the gut microbiota and in vivo biotransformation on the bioactivity of citrus flavonoids. This article discusses the biological fate of citrus flavonoids from the viewpoint of their absorption, distribution, metabolism and excretion in vivo. Many delivery systems have been designed to enhance the oral bioavailability of citrus flavonoids, such as emulsions, self-emulsifying systems, nanoparticles and solid dispersions. The ultimate goal of these delivery systems is to enhance the bioefficacy of citrus flavonoids. Several studies have found that the increased bioavailability leads to enhanced bioefficacy of citrus flavonoids in specific animal models. Regarding the complex dynamics of citrus flavonoids and gut microbiota, the bioavailability-bioactivity relationship is an interesting but under-discussed area. Comprehensively understanding the biological fate and bioefficacy of citrus flavonoids would be helpful to develop functional foods with better health benefits.

Flavonoids against the SARS-CoV-2 induced inflammatory storm

The disease severity of COVID-19, especially in the elderly and patients with co-morbidities, is characterized by hypercytokinemia, an exaggerated immune response associated with an uncontrolled and excessive release of proinflammatory cytokine mediators (cytokine storm). Flavonoids, important secondary metabolites of plants, have long been studied as therapeutic interventions in inflammatory diseases due to their cytokine-modulatory effects. In this review, we discuss the potential role of flavonoids in the modulation of signaling pathways that are crucial for COVID-19 disease, particularly those related to inflammation and immunity. The immunomodulatory ability of flavonoids, carried out by the regulation of inflammatory mediators, the inhibition of endothelial activation, NLRP3 inflammasome, toll-like receptors (TLRs) or bromodomain containing protein 4 (BRD4), and the activation of the nuclear factor erythroid-derived 2-related factor 2 (Nrf2), might be beneficial in regulating the cytokine storm during SARS-CoV-2 infection. Moreover, the ability of flavonoids to inhibit dipeptidyl peptidase 4 (DPP4), neutralize 3-chymotrypsin-like protease (3CL^pro) or to affect gut microbiota to maintain immune response, and the dual action of angiotensin-converting enzyme 2 (ACE-2) may potentially also be applied to the exaggerated inflammatory responses induced by SARS-CoV-2. Based on the previously proven effects of flavonoids in other diseases or on the basis of newly published studies associated with COVID-19 (bioinformatics, molecular docking), it is reasonable to assume positive effects of flavonoids on inflammatory changes associated with COVID-19. This review highlights the current state of knowledge of the utility of flavonoids in the management of COVID-19 and also points to the multiple biological effects of flavonoids on signaling pathways associated with the inflammation processes that are deregulated in the pathology induced by SARS-CoV-2. The identification of agents, including naturally occurring substances such as flavonoids, represents great approach potentially utilizable in the management of COVID-19. Although not clinically investigated yet, the applicability of flavonoids against COVID-19 could be a promising strategy due to a broad spectrum of their biological activities.

Phytochemical characterization of turnip greens (Brassica rapa ssp. rapa): A systematic review

Objective

The Turnip (Brassica rapa L. ssp. rapa) is a leaf and root vegetable grown and consumed worldwide. The consumption of Turnip has been associated with beneficial effects on human health due to their phytochemicals that may control a variety of physiological functions, including antioxidant activity, enzyme regulation, and apoptotic control and the cell cycle. The current systematic review of the literature aims to evaluate both the profile and quantity of phytochemicals commonly found in Turnip greens and to provide perspectives for further investigation.

Methods

This review was conducted following the PRISMA guidelines. Four bibliographic databases (PubMed, Embase, Web-of-Science and Cochrane Central Register of Controlled Trials) were searched to identify published studies until April 8th, 2020 (date last searched) without data and language restriction. Studies were included if they used samples of Turnip greens (the leaves), and evaluated its phytochemical content. Two reviewers independently evaluated the titles and abstracts according to the selection criteria. For each potentially eligible study, two reviewers assessed the full-texts and independently extracted the data using a predesigned data extraction form.

Results

Based on the search strategy 5,077 potentially relevant citations were identified and full texts of 37 studies were evaluated, among which 18 studies were eligible to be included in the current review. The majority of included studies were focused on identification of glucosinolates and isothiocyanates (n = 14, 82%), four studies focused on organic acids, and five studies reported phenolic component profile in Turnip greens. Among included studies nine studies (50%) provided information on phytochemical’s content. We found 129 phytochemicals (19 glucosinolates, 33 glucosinolate-breakdown products, 10 organic acids and 59 polyphenolic compounds) reported in Turnip greens. Flavonoids were mainly present as quercetin, kaempferol and isorhamnetin derivatives; while aliphatic forms were the predominant glucosinolate (gluconapin was the most common across five studies, followed by glucobrassicanapin). In general, the phytochemical content varied among the leaves, tops and Turnip roots.

Conclusions

Emerging evidence suggests the Turnip as a substantial source of diverse bioactive compounds. However, detailed investigation on the pure compounds derived from Turnip green, their bioavailability, transport and metabolism after consumption is further needed. Additional studies on their biological activity are crucial to develop dietary recommendations on the effective dosage and dietary recommendation of Turnip greens for nutrition and health.

The potential of anthocyanins in smart, active, and bioactive eco-friendly polymer-based films: A review

Among the bioactive compounds that are considered important for the food industry, anthocyanins, which are flavonoid compounds presenting antioxidant activity and are responsible for beneficial health effects, have received researchers' attention in the last decades. In addition, anthocyanins are highly reactive and can be used as indicators of foodstuff quality conditions, particularly as a packaging ingredient. Considering this line of work, the eco-friendly film is a novel packaging technology that arose from the concern to reduce non-renewable resources and their impact on the environment. These films can be vehicles for loading bioactive compounds such as anthocyanins. Among the contribution of films in the food industry, we can highlight several potential applications: i) smart film: assess food quality and safety, transmitting food information to consumers and increasing the reliability of their consumption without breaking the packaging; ii) active film: use to preserve food quality through the release of active agents; and iii) bioactive film: carry substances in desired concentrations until their controlled or rapid diffusion within the gastrointestinal tract so that they can promote its benefit to human health. Thus, this review presents anthocyanin extract's potential as a powerful tool to improve the development of eco-friendly films, directing its purpose to the application as smart, active, and bioactive films.

Integration of lncRNA and mRNA profiles to reveal the protective effects of Codonopsis pilosula extract on the gastrointestinal tract of mice subjected to D‑galactose‑induced aging

Codonopsis pilosula is a type of traditional Chinese medicine that exerts an anti‑aging effect and can regulate the gastrointestinal (GI) system. The aim of the present study was to investigate the underlying molecular mechanisms responsible for the anti‑aging effects of Codonopsis pilosula in the GI tract of mice with D‑galactose‑induced aging. First, a successful mouse model of aging was established, and Codonopsis pilosula water extract was then used for treatment. The anti‑aging effects of Codonopsis pilosula on the GI tract were then detected from the perspectives of tissue structure, physiological function and cell ultrastructure. Finally, in order to explore the underlying molecular mechanisms, the expression profiles of lncRNAs and mRNAs in the stomach and intestine were examined using microarray technology. A total of 117 (41 lncRNAs and 76 mRNAs) and 168 (85 lncRNA sand 83 mRNAs) differentially expressed genes associated with the anti‑aging effects of Codonopsis pilosula were identified in the stomach and intestine, respectively. Through integrated analysis of the stomach and intestine, 4 hub RNAs, including 1 lncRNA (LOC105243318) and 3 mRNAs (Fam132a, Rorc and 1200016E24Rik) were identified, which may be associated with the anti‑aging effects of Codonopsis pilosula in the GI tract of aging mice. The Kyoto Encyclopedia of Genes and Genomes analysis revealed that the metabolic pathway was an important pathway underlying the anti‑aging effects of Codonopsis pilosula in the GI tract. On the whole, in the present study, 4 hub RNAs associated with these effects and their regulatory networks were found in the GI tract of aging mice. In addition, the metabolic pathway was found to play an important role in these anti‑aging effects in the GI tract.

Assessment of in-vitro bioaccessibility and antioxidant capacity of phenolic compounds extracts recovered from grapevine bunch stem and cane by-products

Grapevine woody by-products contain bioactive substances, mainly phenolic compounds (PCs), whose beneficial health effects initially depends on their levels of intake and bioavailability. Therefore, in-vitro simulated gastrointestinal digestion (GID; oral, gastric and intestinal phases) was performed to evaluate the bioaccessibility and antioxidant capacity (AC) of PCs extracts recovered from grapevine bunch stem and cane from Malbec grape cultivar. The total PCs in cane and bunch stem extracts were 74 and 20% bioaccessible, respectively. Syringic acid, cinnamic acid, ε-viniferin, naringenin and myricetin were highly bioaccessible, noticeably ε-viniferin in cane extract with 137%. The high bioaccessibility observed, particularly for compounds at high concentration such as ε-viniferin, will help to better understand the bioactive potential of these by-products. In this sense, bunch stems and canes can be considered as new and sustainable sources of bioactive substances for applications as functional ingredients or nutraceuticals in food and pharmaceutical industries.

Phytochemical delivery through nanocarriers: a review

In recent times, phytochemicals encapsulated or conjugated with nanocarriers for delivery to the specific sites have gained considerable research interest. Phytochemicals are mostly plant secondary metabolites which reported to be beneficial for human health and in disease theraphy. However, these compound are large size and polar nature of these compounds, make it difficult to cross the blood-brain barrier (BBB), endothelial lining of blood vessels, gastrointestinal tract and mucosa. Moreover, they are enzymatically degraded in the gastrointestinal tract. Therefore, encapsulation or conjugation of these compounds with nanocrriers could be an alternate way to enhance their bioefficacy by influencing their gastrointestinal stability, rate of absorption and dispersion. This review presents an overview of nanocarriers alternatives which improves therapeutic value and avoid toxicity, by releasing bioactive compounds specifically at target tissues with enhanced stability and bioavailability. Future investigations may emphasize on deciphering the structural changes in nanocarriers during digestion and absorption, the difference between in-vitro and in-vivo digestion simulations, and impact of nanocarriers on the metabolism of phytochemicals.

Differential protection by anthocyanin-rich bilberry extract and resveratrol against lipid micelle-induced oxidative stress and monolayer permeability in Caco-2 intestinal epithelial cells

Excess dietary fat, and associated bile acids, can impair intestinal barrier integrity, produce intestinal or systemic inflammation and promote tumorigenesis.

Influence of Glycyrrhiza glabra Extract on Growth, Gene Expression of Gut Integrity, and Campylobacter jejuni Colonization in Broiler Chickens

Phytogenic feed additives have been gaining considerable interest due to their ability to improve gut health and thereby performance of broiler chickens. The impact of Glycyrrhiza glabra (licorice) extract (GE) on expression of genes coding for tight junction proteins and gut protection and Campylobacter jejuni colonization in broilers has not been discussed until now. Thus, the current study assessed the effective dose of GE for maximum growth in broiler chickens, clear-cut molecular mechanisms related to integrity and health of intestine, and controlling C. jejuni colonization. Over a 35-day feeding period, a total of 500 Ross broiler chicks were allocated to five groups; the first group was fed a control diet without GE and the second group to the fifth group were fed a control diet with GE (0.25, 0.5, 1, and 2 g/kg of diet); each group comprised 100 chicks with 10 replicates (10 birds/replicate). Birds fed GE had an improved body weight gain and feed conversion ratio. Furthermore, the highest body weight gain was observed in the group that received 1 g/kg of GE (P < 0.05). The expression of genes coding for tight junction proteins [occludin and junctional adhesion molecules (JAM)] was upregulated in all groups supplemented with GE. Moreover, birds fed 1 g/kg of GE exhibited the maximum gene expression of occludin and JAM [0.2 and 0.3 fold change, respectively (P < 0.05)]. In relation to enterocyte protective genes [glucagon-like peptide (GLP-2) and fatty acid-binding protein (FABP-6)], use of GE significantly upregulated expression of GLP-2 gene with 0.8 fold change in 2 g/kg of the GE supplemented group (P < 0.05) while the expression of FABP-6 gene was not affected by GE supplementation (P > 0.05). After challenge with C. jejuni, the expression of mucin (MUC-2) gene was upregulated and the inflammatory markers such as Toll-like receptors (TLR-4) and interleukin (IL-1β) were downregulated with increasing level of supplemented GE (P < 0.05). The mean log10 count of C. jejuni in cecal samples after 7 days post-infection by culture and real-time qPCR was decreased in groups fed GE in a dose-dependent manner (P < 0.05). In addition, the highest reduction of C. jejuni count in cecal samples by culture and real-time qPCR was observed in the group fed 2 g/kg of GE (2.58 and 2.28 log10 CFU/g, respectively). Results from this study suggested that G. glabra extract (1 g/kg) improved growth performance of broiler chickens, as well as influenced the maintenance of intestinal integrity and reduced C. jejuni shedding from infected birds.

Spice fixed oils as a new source of γ-oryzanol: nutraceutical characterization of fixed oils from selected spices

γ-Oryzanol is an important group of nutraceuticals that play a key role in addressing metabolic disorders. This study, for the first time, examined volatile-free spice fixed oils (FOs) as an alternate plant source for γ-oryzanol and other nutraceuticals (phenolics, flavonoids, phytosterols, and tocopherols) using HPLC, HR-MS and NMR. The in vitro antioxidant activities of FOs were also analysed. The selected spices were Alpinia galanga, Cinnamomum zeylanicum, Trigonella foenum-graecum, Foeniculum vulgare and Myristica fragrans. The major polyphenols and flavonoids quantified were gallic, protocatechuic, vanillic, syringic, para-coumaric, ferulic, rutin, trans-cinnamic, and quercetin. T. foenum-graecum FOs recorded high levels of ergosterol (48.56 mg/100 g) and stigmasterol (247.36 mg/100 g). The fucosterol levels were high in A. galanga (268.31 mg/100 g) FOs, whereas C. zeylanicum FOs showed high content of β-sitosterols (7037.77 mg/100 g). C. zeylanicum and T. foenum-graecum FOs recorded high α-tocopherol content (47.55 and 15.96 mg/100 g respectively). C. zeylanicum FOs showed high levels of three ferulates, namely, cycloartenyl ferulate, 24-methylene cycloartenyl ferulate and β-sitosteryl ferulate, whose contents were 89.42, 170.23 and 50.23 mg/100 g respectively which was confirmed by HRMS with a molecular mass (m/z) of 601.45, 615.47, and 589.45 respectively. Further, γ-oryzanol ferulates in C. zeylanicum FOs were confirmed by 1H-NMR analysis. The acidified methanolic extractives of FOs showed high free radical scavenging activity and antioxidant potential. These spice FOs have excellent antioxidant activities, and are novel potential functional ingredients against lifestyle disorders.

A Review of the Role of Flavonoids in Peptic Ulcer (2010-2020)

Peptic ulcers are characterized by erosions on the mucosa of the gastrointestinal tract that may reach the muscle layer. Their etiology is multifactorial and occurs when the balance between offensive and protective factors of the mucosa is disturbed. Peptic ulcers represent a global health problem, affecting millions of people worldwide and showing high rates of recurrence. Helicobacter pylori infection and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most important predisposing factors for the development of peptic ulcers. Therefore, new approaches to complementary treatments are needed to prevent the development of ulcers and their recurrence. Natural products such as medicinal plants and their isolated compounds have been widely used in experimental models of peptic ulcers. Flavonoids are among the molecules of greatest interest in biological assays due to their anti-inflammatory and antioxidant properties. The present study is a literature review of flavonoids that have been reported to show peptic ulcer activity in experimental models. Studies published from January 2010 to January 2020 were selected from reference databases. This review refers to a collection of flavonoids with antiulcer activity in vivo and in vitro models.

Health Effects of Grape Seed and Skin Extracts and Their Influence on Biochemical Markers

This review is focused on the study of the effects of grape seed and skin extract (GSSE) on human health. GSSE contains high concentrations of important polyphenolic substances with high biological activity. This review is a summary of studies that investigate the effects of GSSE on diabetes mellitus, cardiovascular disease and cancer, its neuroprotective effect, and its effects on the gastrointestinal tract and other health complications related to these diseases. The results of the studies confirm that the anti-inflammatory, antiapoptotic, and pro-proliferative effects of “Vitis vinifera L.” seed extract reduce the level of oxidative stress and improve the overall lipid metabolism.

Important Flavonoids and Their Role as a Therapeutic Agent

Flavonoids are phytochemical compounds present in many plants, fruits, vegetables, and leaves, with potential applications in medicinal chemistry. Flavonoids possess a number of medicinal benefits, including anticancer, antioxidant, anti-inflammatory, and antiviral properties. They also have neuroprotective and cardio-protective effects. These biological activities depend upon the type of flavonoid, its (possible) mode of action, and its bioavailability. These cost-effective medicinal components have significant biological activities, and their effectiveness has been proved for a variety of diseases. The most recent work is focused on their isolation, synthesis of their analogs, and their effects on human health using a variety of techniques and animal models. Thousands of flavonoids have been successfully isolated, and this number increases steadily. We have therefore made an effort to summarize the isolated flavonoids with useful activities in order to gain a better understanding of their effects on human health.

Preventative and Therapeutic Potential of Flavonoids in Peptic Ulcers

Peptic ulcer disease is a common gastrointestinal tract disorder that affects up to 20% of the population of the world. Treatment of peptic ulcer remains challenging due to the limited effectiveness and severe side effects of the currently available drugs. Hence, natural compounds, owing to their medicinal, ecological, and other safe properties, are becoming popular potential candidates in preventing and treating peptic ulcers. Flavonoids, the most abundant polyphenols in plants, exhibit gastroprotective effects against peptic ulcer both in vivo and in vitro. In this review, we summarized the anti-ulcer functions and mechanisms, and also the bioavailability, efficacy, and safety, of flavonoid monomers in the gastrointestinal tract. Flavonoids exerted cytoprotective and rehabilitative effects by not only strengthening defense factors, such as mucus and prostaglandins, but also protecting against potentially harmful factors via their antioxidative, anti-inflammatory, and antibacterial activities. Although controlled clinical studies are limited at present, flavonoids have shown a promising preventable and therapeutic potential in peptic ulcers.

Gut Microbiota Dysbiosis-Immune Hyperresponse-Inflammation Triad in Coronavirus Disease 2019 (COVID-19): Impact of Pharmacological and Nutraceutical Approaches

Coronavirus Disease 2019 (COVID-19) is a pandemic infection caused by a novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients present a complex clinical picture that, in severe cases, evolves to respiratory, hepatic, gastrointestinal, and neurological complications, and eventually death. The underlying pathophysiological mechanisms are complex and multifactorial and have been summarized as a hyperresponse of the immune system that originates an inflammatory/cytokine storm. In elderly patients, particularly in those with pre-existing cardiovascular, metabolic, renal, and pulmonary disorders, the disease is particularly severe, causing prolonged hospitalization at intensive care units (ICU) and an increased mortality rate. Curiously, the same populations have been described as more prone to a gut microbiota (GM) dysbiosis profile. Intestinal microflora plays a major role in many metabolic and immune functions of the host, including to educate and strengthen the immune system to fight infections, namely of viral origin. Notably, recent studies suggest the existence of GM dysbiosis in COVID-19 patients. This review article highlights the interplay between the triad GM dysbiosis-immune hyperresponse-inflammation in the individual resilience/fragility to SARS-CoV-2 infection and presents the putative impact of pharmacological and nutraceutical approaches on the triumvirate, with focus on GM.

Polyphenols by Generating H2O2, Affect Cell Redox Signaling, Inhibit PTPs and Activate Nrf2 Axis for Adaptation and Cell Surviving: In Vitro, In Vivo and Human Health

Human health benefits from different polyphenols molecules consumption in the diet, derived mainly by their common activities in the gastrointestinal tract and at the level of blood micro-capillary. In the stomach, intestine and colon, polyphenols act as reducing agents preventing lipid peroxidation, generation and absorption of AGEs/ALEs (advanced glycation end products/advanced lipid oxidation end products) and postprandial oxidative stress. The low absorption of polyphenols in blood does not support their activity as antioxidants and their mechanism of activity is not fully understood. The results are from in vitro, animal and human studies, detected by relevant oxidative stress markers. The review carries evidences that polyphenols, by generating H₂O₂ at nM concentration, exogenous to cells and organs, act as activators of signaling factors increasing cell Eustress. When polyphenols attain high concentration in the blood system, they generate H₂O₂ at µM concentration, acting as cytotoxic agents and Distress. Pre-treatment of cells or organisms with polyphenols, by generating H₂O₂ at low levels, inhibits cellular PTPs (protein tyrosine phosphatases), inducing cell signaling through transcription of the Nrf2 (nuclear factor erythroid 2-related factor 2) axis of adaptation and protection to oxidation stress. Polyphenols ingestion at the right amount and time during the meal acts synergistically at the level of the gastrointestinal tract (GIT) and blood system, for keeping the redox homeostasis in our organism and better balancing human health.

In Vitro Effects of Ginseng and the Seed of Zizyphus jujuba var. spinosa on Gut Microbiota of Rats with Spleen Deficiency

Ginseng and the seed of Zizyphus jujuba var. spinosa, which are traditional Chinese medicinal materials, were often used in ancient Chinese recipes as a pair of medicines. They can replenish the primordial qi and tonify the spleen. This study investigated the effects of ginseng and the seed of Zizyphus jujuba var. spinosa (GS) extract on gut microbiota diversity in rats with spleen deficiency syndrome (SDS). A total of 52 compounds (including 16 flavonoids, 35 saponins, and 1 alkaloid) were identified and analyzed from the GS extract by UPLC-Q-Orbitrap-MS/MS. The GS extract significantly increased the relative abundance of Firmicutes and Bacteroidetes in rats with SDS but decreased that of Proteobacteria and Actinobacteria. At the genus level, the GS extract significantly increased the relative abundance of Lactobacillus and Bifidobacterium in rats with SDS but decreased that of Streptococcus, Escherichia-Shigella, Veillonella, and Enterococcus. In addition, the GS extract influenced glucose and amino acid metabolism. In summary, the results showed that the GS extract changed the structure and diversity of gut microbiota in rats with SDS and balanced the metabolic process.

(-)-Epicatechin and the comorbidities of obesity

Obesity has major adverse consequences on human health contributing to the development of, among others, insulin resistance and type 2 diabetes, cardiovascular disease, non-alcoholic fatty liver disease, altered behavior and cognition, and cancer. Changes in dietary habits and lifestyle could contribute to mitigate the development and/or progression of these pathologies. This review will discuss current evidence on the beneficial actions of the flavan-3-ol (-)-epicatechin (EC) on obesity-associated comorbidities. These benefits can be in part explained through EC's capacity to mitigate several common events underlying the development of these pathologies, including: i) high circulating levels of glucose, lipids and endotoxins; ii) chronic systemic inflammation; iii) tissue endoplasmic reticulum and oxidative stress; iv) insulin resistance; v) mitochondria dysfunction and vi) dysbiosis. The currently known underlying mechanisms and cellular targets of EC's beneficial effects are discussed. While, there is limited evidence from human studies supplementing with pure EC, other studies involving cocoa supplementation in humans, pure EC in rodents and in vitro studies, support a potential beneficial action of EC on obesity-associated comorbidities. This evidence also stresses the need of further research in the field, which would contribute to the development of human dietary strategies to mitigate the adverse consequences of obesity.

The sweet side of dark chocolate for chronic kidney disease patients

Chocolate is a widely appreciated foodstuff with historical appreciation as a food from the gods. In addition to its highly palatable taste, it is a rich source of (poly)phenolics, which have several proposed salutogenic effects, including neuroprotective anti-inflammatory, anti-oxidant and cardioprotective capabilities. Despite the known benefits of this ancient foodstuff, there is a paucity of information on the effects of chocolate in the context of chronic kidney disease (CKD). This review focusses on the potential salutogenic contribution of chocolate intake, to mitigate inflammatory and oxidative burden in CKD, its potential, for cardiovascular protection and on the maintenance of diversity in gut microbiota, as well as clinical perspectives, on regular chocolate intake by CKD patients.

Polyphenols, the new frontiers of prebiotics

There is a growing interest in the identification of molecules capable to promote health and with a concurrent potential for technological applications. Prebiotics are functional ingredients naturally occurring in some plant and animal foods that since many decades stimulated considerable attention from the pharmaceutical and food industries due to their positive health effects. Together the well-known biomolecules with ascertained prebiotic effect, in last year new molecules were finally recognized as prebiotics, so capable to improve the health of an organism, also through the positive effect exerted on host microbiota. Among the so-called prebiotics, a special mention should be given to polyphenols, probably the most important, or at least among the most important secondary metabolites produced by the vegetal kingdom. This short chapter wants to emphasize polyphenols and, after briefly describing the individual microbiome, to illustrate how polyphenols can, through their influence on the microbiome, have a positive effect on the health of the individual in general, and on some pathologies in particular, for which the role of a bad status of the individual microbiome has been definitively established.

Flavonoids and Mitochondria: Activation of Cytoprotective Pathways?

A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and biosynthesis these organelles are triggers and/or end-effectors of a large number of signaling pathways. Their role in the regulation of the intrinsic apoptotic pathway, calcium homeostasis, and reactive oxygen species signaling is well documented. In this review, we aim to characterize the prospects of influencing cytoprotective mitochondrial signaling routes by natural substances of plant origin, namely, flavonoids (e.g., flavanones, flavones, flavonols, flavan-3-ols, anthocyanidins, and isoflavones). Flavonoids are a family of widely distributed plant secondary metabolites known for their beneficial effects on human health and are widely applied in traditional medicine. Their pharmacological characteristics include antioxidative, anticarcinogenic, anti-inflammatory, antibacterial, and antidiabetic properties. Here, we focus on presenting mitochondria-mediated cytoprotection against various insults. Thus, the role of flavonoids as antioxidants and modulators of antioxidant cellular response, apoptosis, mitochondrial biogenesis, autophagy, and fission and fusion is reported. Finally, an emerging field of flavonoid-mediated changes in the activity of mitochondrial ion channels and their role in cytoprotection is outlined.

Ellagic acid protects Caco-2 cell monolayers against inflammation-induced permeabilization

Chronic intestinal inflammation involves a cycle of oxidative stress, activation of redox sensitive transcription factors, and barrier permeabilization. The latter can lead to systemic inflammation and its associated co-morbidities. Diet can play a major role in the modulation of intestinal inflammation. Among plant bioactives, ellagic acid (EA) was reported to inhibit inflammatory bowel disease in animal models. This work investigated the mechanisms by which EA inhibits tumor necrosis factor alpha (TNFα)-induced inflammation, oxidative stress, and loss of barrier integrity. Caco-2 cells differentiated into an intestinal epithelial cell monolayer were incubated with TNFα (10 ng/ml), in the presence of different EA concentrations. TNFα triggered interleukin (IL) 6 and 8 release into the medium, which was inhibited by EA in a dose-dependent manner (IC₅₀ = 17.3 μM for IL-6). TNFα also led to: i) increased ICAM-1 and NLRP3 expression; ii) loss of epithelial barrier function; iii) increased oxidant production from NOX and mitochondrial origin; iv) NF-κB and ERK1/2 activation; and v) increased MLCK gene expression and MLC phosphorylation. EA (10-40 μM) inhibited all these adverse effects of TNFα. EA mainly acted through NF-κB and ERK1/2 inhibition, breaking the cycle of inflammation, oxidative stress, redox-sensitive pathway (e.g. NF-κB, ERK1/2) activation and intestinal permeabilization. This suggests that consumption of EA, via foods or supplements, may afford a strategy to mitigate intestinal inflammation and its associated co-morbidities.

The inhibitory effect of ECG and EGCG dimeric procyanidins on colorectal cancer cells growth is associated with their actions at lipid rafts and the inhibition of the epidermal growth factor receptor signaling

Colorectal cancer (CRC) is one of the most common cancers worldwide. Epidemiological studies indicate that consumption of fruits and vegetables containing procyanidins is associated with lower CRC risk. This study investigated the capacity of two dimeric procyanidins composed of epicatechin gallate (ECG) or epigallocatechin gallate (EGCG) isolated from persimmons, to inhibit CRC cell growth and promote apoptosis, characterizing the underlying mechanisms. ECG and EGCG dimers reduced the growth of five human CRC cell lines in a concentration (10-60 μM)- and time (24-72 h)-dependent manner, with a 72 h-IC50 value in Caco-2 cells of 10 and 30 μM, respectively. ECG and EGCG dimers inhibited Caco-2 cell proliferation by arresting the cell cycle in G2/M phase and by inducing apoptosis via the mitochondrial pathway. In addition, ECG and EGCG dimers inhibited cell migration, invasion, and adhesion, decreasing the activity of matrix metalloproteinases (MMP-2/9). Mechanistically, ECG and EGCG dimers inhibited the activation of lipid raft-associated epidermal growth factor (EGF) receptor (EGFR), without affecting its localization at lipid rafts. In particular, ECG and EGCG dimers reduced EGFR phosphorylation at Tyr1068 residue, prevented EGFR dimerization and activation upon stimulation, and induced EGFR internalization both in the absence and presence of EGF. Furthermore, ECG and EGCG dimers increased EGFR phosphorylation at Tyr1045 residue, providing a docking site for ubiquitin ligase c-Cbl and induced EGFR degradation by the proteasome. Downstream of EGFR, ECG and EGCG dimers inhibited the activation of the MEK/ERK1/2 and PI3K/AKT signaling pathways, downregulating proteins involved in the modulation of cell survival. In conclusion, ECG and EGCG dimers reduced CRC cell growth by inhibiting EGFR activation at multiple steps, including the disruption of lipid rafts integrity and promoting EGFR degradation. These results shed light on a potential molecular mechanism on how procyanidins-rich diets may lower CRC risk.

Physiological relevance of food antioxidants

Dietary antioxidants are associated with prevention of oxidative stress related chronic diseases including certain types of cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases. In recent years, there has been a growing interest in extending the knowledge on their physiological effects in human body. There are numbers of epidemiological, clinical, meta-analysis, and in vitro studies to explain formation mechanisms of each chronic diseases as well as the potential effects of dietary antioxidants on these diseases and gut health. Comprehensive studies for food antioxidants' journey from dietary intake to target tissues/organs deserve a serious consideration to have a clear understanding on the physiological effects of dietary antioxidants. Therefore, absorption and metabolism of dietary antioxidants, and the factors affecting their absorption, such as solubility of antioxidants, food matrix, and interaction between antioxidants have been evaluated in several research articles. This chapter provides an overview about potential health effects of dietary antioxidants considering with their absorption and metabolism in human body.

Isolation and Characterization of Blueberry Polyphenolic Components and Their Effects on Gut Barrier Dysfunction

Highbush blueberries contain anthocyanins and proanthocyanidins that have antimicrobial and anti-inflammatory bioactivities. We isolated and characterized three polyphenolic fractions, a total polyphenol fraction (TPF), an anthocyanin-enriched fraction (AEF), and a proanthocyanidin-enriched fraction (PEF), from freeze-dried blueberry powder and evaluated their effects on an in vitro model of gut barrier dysfunction. High-performance liquid chromatography chromatograms illustrate successful fractionation of the blueberry powder into TPF, AEF, and PEF. AEF contained 21 anthocyanins, and PEF contained proanthocyanidin oligomers of (epi)catechin with primarily B-type interflavan bonds. The model uses a strain of Escherichia coli to disrupt a Caco-2 cell monolayer on Transwell inserts. Barrier function was measured by transepithelial electrical resistance (TEER), a marker of membrane permeability. All fractions were able to restore TEER values after an E. coli challenge when compared to the control, while AEF was able to attenuate the E. coli-induced decrease in TEER in a dose-dependent manner.

The Influence of Nutrients on Inflammatory Bowel Diseases

Inflammatory bowel diseases is a group of inflammatory diseases. The pathogenesis of diseases is multifactorial, which may include a Western-type diet. Diseases occur with periods of recurrence and remission. Many factors can have a beneficial effect on reducing the frequency of recurrence and prolonging the remission period. Such ingredients include dietary fibre, mono- and polyunsaturated fatty acids, certain vitamins (D, C, and E), flavonoids, and minerals such as zinc and selenium. Properly selected nutrition might be an integral part of the treatment of patients with Crohn's disease or ulcerative colitis.

The Gastrointestinal Exertional Heat Stroke Paradigm: Pathophysiology, Assessment, Severity, Aetiology and Nutritional Countermeasures

Exertional heat stroke (EHS) is a life-threatening medical condition involving thermoregulatory failure and is the most severe condition along a continuum of heat-related illnesses. Current EHS policy guidance principally advocates a thermoregulatory management approach, despite growing recognition that gastrointestinal (GI) microbial translocation contributes to disease pathophysiology. Contemporary research has focused to understand the relevance of GI barrier integrity and strategies to maintain it during periods of exertional-heat stress. GI barrier integrity can be assessed non-invasively using a variety of in vivo techniques, including active inert mixed-weight molecular probe recovery tests and passive biomarkers indicative of GI structural integrity loss or microbial translocation. Strenuous exercise is strongly characterised to disrupt GI barrier integrity, and aspects of this response correlate with the corresponding magnitude of thermal strain. The aetiology of GI barrier integrity loss following exertional-heat stress is poorly understood, though may directly relate to localised hyperthermia, splanchnic hypoperfusion-mediated ischemic injury, and neuroendocrine-immune alterations. Nutritional countermeasures to maintain GI barrier integrity following exertional-heat stress provide a promising approach to mitigate EHS. The focus of this review is to evaluate: (1) the GI paradigm of exertional heat stroke; (2) techniques to assess GI barrier integrity; (3) typical GI barrier integrity responses to exertional-heat stress; (4) the aetiology of GI barrier integrity loss following exertional-heat stress; and (5) nutritional countermeasures to maintain GI barrier integrity in response to exertional-heat stress.

Defying Multidrug Resistance! Modulation of Related Transporters by Flavonoids and Flavonolignans

Multidrug resistance (MDR) is a major challenge for the 21th century in both cancer chemotherapy and antibiotic treatment of bacterial infections. Efflux pumps and transport proteins play an important role in MDR. Compounds displaying inhibitory activity toward these proteins are prospective for adjuvant treatment of such conditions. Natural low-cost and nontoxic flavonoids, thanks to their vast structural diversity, offer a great pool of lead structures with broad possibility of chemical derivatizations. Various flavonoids were found to reverse both antineoplastic and bacterial multidrug resistance by inhibiting Adenosine triphosphate Binding Cassette (ABC)-transporters (human P-glycoprotein, multidrug resistance-associated protein MRP-1, breast cancer resistance protein, and bacterial ABC transporters), as well as other bacterial drug efflux pumps: major facilitator superfamily (MFS), multidrug and toxic compound extrusion (MATE), small multidrug resistance (SMR) and resistance-nodulation-cell-division (RND) transporters, and glucose transporters. Flavonoids and particularly flavonolignans are therefore highly prospective compounds for defying multidrug resistance.

Flavonoids as Anticancer Agents

Flavonoids are polyphenolic compounds subdivided into 6 groups: isoflavonoids, flavanones, flavanols, flavonols, flavones and anthocyanidins found in a variety of plants. Fruits, vegetables, plant-derived beverages such as green tea, wine and cocoa-based products are the main dietary sources of flavonoids. Flavonoids have been shown to possess a wide variety of anticancer effects: they modulate reactive oxygen species (ROS)-scavenging enzyme activities, participate in arresting the cell cycle, induce apoptosis, autophagy, and suppress cancer cell proliferation and invasiveness. Flavonoids have dual action regarding ROS homeostasis—they act as antioxidants under normal conditions and are potent pro-oxidants in cancer cells triggering the apoptotic pathways and downregulating pro-inflammatory signaling pathways. This article reviews the biochemical properties and bioavailability of flavonoids, their anticancer activity and its mechanisms of action.