The gut microbiota metabolite urolithin A, but not other relevant urolithins, induces p53-dependent cellular senescence in human colon cancer cells

Urolithin A affects cellular migration and modulates matrix metalloproteinase expression in colorectal cancer cells

Colorectal cancer (CRC) is the world's second most common gastrointestinal malignancy. Preventing tumor cell proliferation and dissemination is critical for patient survival. Polyphenols have a variety of health advantages and can help prevent cancer. The current study examined different cellular activities of the gut-microbiota metabolite urolithin A (UA) on several colon cancer cell lines. The results revealed that UA suppressed cell growth in a dose- and time-dependent manner. In the current investigation, UA substantially affected cell migration in the wound-healing experiment and greatly decreased the number of colonies generated in each CRC cell culture. UA decreased cellular migration in CRC cells 48 h after treatment, which was significant (p < .001) compared to the migration rate in untreated cells. When compared to untreated cells, UA slowed the process of colony formation by reducing the number of colonies or altering their morphological shape. The western blot analysis investigation revealed that UA inhibits cellular metastasis by lowering the expression levels of matrix metalloproteinases 1 and 2 (MMP1 and MMP2) by more than 43% and 41% (p < .001) in HT29, 28% and 149% (p < .001) in SW480, and 90% and 74% (p < .001) in SW620, respectively, at a 100 µM dosage of UA compared to the control. Surprisingly, at a 100 µM dosage of UA, the expression levels of the tissue inhibitor of metalloproteinases 1 (TIMP1) were elevated in HT29, SW480, and SW620 cells treated with 100 µM of UA by more than 89%, 57%, and 29%, respectively. Our findings imply that UA has anticancer properties and might be used therapeutically to treat CRC. The findings provided the first indication of the influence of UA on cellular migration and metastasis in colon cancer cells. All of these data showed that UA might be used as an adjuvant therapy in the treatment of various forms of CRC.

Polyphenolic Characterization and Anti-Inflammatory Effect of In Vitro Digested Extracts of Echinacea purpurea L. Plant Parts in an Inflammatory Model of Human Colon Cells

Echinacea purpurea L. (EP) preparations are globally popular herbal supplements known for their medicinal benefits, including anti-inflammatory activities, partly related to their phenolic composition. However, regarding their use for the management of inflammation-related intestinal diseases, the knowledge about the fate of orally ingested constituents throughout the human gastrointestinal tract and the exposition of in vitro digested extracts in relevant inflammatory models are unknown. This study investigated for the first time the impact of in vitro gastrointestinal digestion (INFOGEST) on the phenolic composition and anti-inflammatory properties of EP extracts from flowers (EF), leaves (EL), and roots (ER) on IL-1β-treated human colon-derived CCD-18Co cells. Among the seven hydroxycinnamic acids identified using HPLC-UV-MS/MS, chicoric and caftaric acids showed the highest concentrations in EL, followed by EF and ER, and all extracts exerted significant reductions in IL-6, IL-8, and PGE2 levels. After digestion, despite reducing the bioaccessibility of their phenolics, the anti-inflammatory effects were preserved for digested EL and, to a lesser extent, for EF, but not for digested ER. The lower phenolic content in digested EF and ER could explain these findings. Overall, this study emphasizes the potential of EP in alleviating intestinal inflammatory conditions and related disorders.

Urolithin A conjugation with NSAIDs inhibits its glucuronidation and maintains improvement of Caco-2 monolayers' barrier function

Urolithin A (UA) is an ellagitannin-derived postbiotic metabolite which emerged as a promising health-boosting agent, promoting mitophagy, improving skeletal muscle function, and suppressing the inflammatory response. However, phase II intestinal metabolism severely limits its biopotency, leading to the formation of nonactive glucuronides. To address this constraint, a set of new UA derivatives (UADs), conjugated with nonsteroidal anti-inflammatory drugs (NSAIDs), was synthesized. The bioavailability and inhibitory activity of UADs against UA-glucuronidation were evaluated using differentiated Caco-2 cell monolayers. Parallelly, after the administration of tested substances, the transepithelial electrical resistance (TEER) of the cell monolayers was continuously monitored using the CellZscope device. Though investigated UADs did not penetrate Caco-2 monolayers, all of them significantly suppressed the glucuronidation rate of UA, while conjugates with diclofenac increased the concentration of free molecule on the basolateral side. Moreover, esters of UA with diclofenac (DicloUA) and aspirin (AspUA) positively influenced cell membrane integrity. Western blot analysis revealed that some UADs, including DicloUA, increased the expression of pore-sealing tight junction proteins and decreased the level of pore-forming claudin-2, which may contribute to their beneficial activity towards the barrier function. To provide comprehensive insight into the mechanism of action of DicloUA, Caco-2 cells were subjected to transcriptomic analysis. Next-generation sequencing (NGS) uncovered substantial changes in the expression of genes involved, for instance, in multivesicular body organization and zinc ion homeostasis. The results presented in this study offer new perspectives on the beneficial effects of modifying UA's structure on its intestinal metabolism and bioactivity in vitro.

Absorption and Metabolism of Urolithin A and Ellagic Acid in Mice and Their Cytotoxicity in Human Colorectal Cancer Cells

Background

Ellagic acid is a natural polyphenol compound found in pomegranates, walnuts, and many berries. It is not easily absorbed, but it could be metabolized to urolithins by the gut microbiota. Urolithin A, one of the ellagic acid metabolites, has been proved to prolong the lifespan of C. elegans and increases muscle function of mice. The purpose of this current study was to analyze the absorption and metabolites of urolithin A and ellagic acid in mice and the anticancer effects of urolithin A, urolithin B, and ellagic acid in colorectal cancer cells.

Methods

Urolithin A and urolithin B were synthesized and analyzed by HPLC and NMR. A pharmacokinetic study of urolithin A was performed in mice by analyzing urolithin A and its metabolites in urines. Absorption and biotransformation of ellagic acid were also studied in mice by analyzing the plasma, liver, and feces. The cytotoxicity of urolithin A, urolithin B, and ellagic acid was assayed in SW480, SW620, HCT 116, and HT-29 cells.

Results

Urolithin A and urolithin B were synthesized and purified to reach 98.1% and 99% purity, respectively, and the structures were identified by NMR. In urolithin A intake analysis, urolithin A was only detectable at 3 h, not at 6-24 h; it suggested that urolithin A was rapidly metabolized to some unknown metabolites. Using UPLC-MS/MS analysis, the metabolites might be urolithin A 3-O-glucuronide, urolithin A 3-sulfate, and urolithin A-sulfate glucuronide. After feeding mice with ellagic acid for consecutive 14 days, ellagic acid contents could be detected in the fecal samples, but not in plasma and liver, and urolithin A was not detected in all samples. It suggests that ellagic acid is not easily absorbed and that the biotransformation of ellagic acid to urolithin A by intestinal flora might be very low. From the cytotoxicity assay, it was found that there was anticancer effect in urolithin A and urolithin B but not in ellagic acid. In contrast, ellagic acid promoted the proliferation of SW480 and SW620 cells.

Role of hypoxia in cellular senescence

Senescent cells persist and continuously secrete proinflammatory and tissue-remodeling molecules that poison surrounding cells, leading to various age-related diseases, including diabetes, atherosclerosis, and Alzheimer's disease. The underlying mechanism of cellular senescence has not yet been fully explored. Emerging evidence indicates that hypoxia is involved in the regulation of cellular senescence. Hypoxia-inducible factor (HIF)- 1α accumulates under hypoxic conditions and regulates cellular senescence by modulating the levels of the senescence markers p16, p53, lamin B1, and cyclin D1. Hypoxia is a critical condition for maintaining tumor immune evasion, which is promoted by driving the expression of genetic factors (such as p53 and CD47) while triggering immunosenescence. Under hypoxic conditions, autophagy is activated by targeting BCL-2/adenovirus E1B 19-kDa interacting protein 3, which subsequently induces p21WAF1/CIP1 as well as p16Ink4a and increases β-galactosidase (β-gal) activity, thereby inducing cellular senescence. Deletion of the p21 gene increases the activity of the hypoxia response regulator poly (ADP-ribose) polymerase-1 (PARP-1) and the level of nonhomologous end joining (NHEJ) proteins, repairs DNA double-strand breaks, and alleviates cellular senescence. Moreover, cellular senescence is associated with intestinal dysbiosis and an accumulation of D-galactose derived from the gut microbiota. Chronic hypoxia leads to a striking reduction in the amount of Lactobacillus and D-galactose-degrading enzymes in the gut, producing excess reactive oxygen species (ROS) and inducing senescence in bone marrow mesenchymal stem cells. Exosomal microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play important roles in cellular senescence. miR-424-5p levels are decreased under hypoxia, whereas lncRNA-MALAT1 levels are increased, both of which induce cellular senescence. The present review focuses on recent advances in understanding the role of hypoxia in cellular senescence. The effects of HIFs, immune evasion, PARP-1, gut microbiota, and exosomal mRNA in hypoxia-mediated cell senescence are specifically discussed. This review increases our understanding of the mechanism of hypoxia-mediated cellular senescence and provides new clues for anti-aging processes and the treatment of aging-related diseases.

Urolithin A in Health and Diseases: Prospects for Parkinson's Disease Management

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder characterized by a complex pathophysiology and a range of symptoms. The prevalence increases with age, putting the ageing population at risk. Disease management includes the improvement of symptoms, the comfort of the patient's life, and palliative care. As there is currently no cure, growing evidence points towards the beneficial role of polyphenols on neurodegeneration. Numerous studies indicate the health benefits of the family of urolithins, especially urolithin A (UA). UA is a bacterial metabolite produced by dietary ellagitannins and ellagic acid. An expanding body of literature explores the involvement of the compound in mitochondrial health, and its anti-inflammatory, anti-oxidant, and anti-apoptotic properties. The review organizes the existing knowledge on the role of UA in health and diseases, emphasizing neurodegenerative diseases, especially PD. We gathered data on the potential neuroprotective effect in in vivo and in vitro models. We discussed the possible mechanisms of action of the compound and related health benefits to give a broader perspective of potential applications of UA in neuroprotective strategies. Moreover, we projected the future directions of applying UA in PD management.

Urolithin A as a Potential Agent for Prevention of Age-Related Disease: A Scoping Review

The aging of an organism is hallmarked by systemic loss of functional tissue, resulting in increased fragility and eventual development of age-related neurodegenerative, musculoskeletal, cardiovascular, and neoplastic diseases. Growing scientific evidence points to mitochondrial dysfunction as a key contributor in the aging process and subsequent development of age-related pathologies. Under normal physiologic conditions, the body removes dysfunctional mitochondria via an autophagic process known as mitophagy. Urolithin A (UA), a metabolite produced when gut microflora digests the polyphenol compounds ellagitannin and ellagic acid, is a known inducer of mitophagy via several identified mechanisms of action. The primary objective of this scoping review is to identify and summarize the clinical relevance of UA supplementation in the prevention of age-related pathology and diseases. A computer-assisted literature review was performed using PubMed and EMBASE for primary source research articles examining UA supplementation and aging-related pathologies. A total of 293 articles were initially identified from a database search, and 15 articles remained for inclusion in this review, based on predetermined criteria. Analysis of the 15 identified publications demonstrated that UA holds potential as a dietary intervention for slowing the progression of aging and preventing the development of age-related disease. This review also illustrates the potential role that mitochondrial health and inflammation play in the progression of age-related pathology. Identifying the clinical relevance of UA supplementation in the prevention of age-related pathology and diseases will help further the focus of research on treatments that may improve the longevity and quality of life in patients at risk for these comorbidities.

Signaling pathways in cancer metabolism: mechanisms and therapeutic targets

A wide spectrum of metabolites (mainly, the three major nutrients and their derivatives) can be sensed by specific sensors, then trigger a series of signal transduction pathways and affect the expression levels of genes in epigenetics, which is called metabolite sensing. Life body regulates metabolism, immunity, and inflammation by metabolite sensing, coordinating the pathophysiology of the host to achieve balance with the external environment. Metabolic reprogramming in cancers cause different phenotypic characteristics of cancer cell from normal cell, including cell proliferation, migration, invasion, angiogenesis, etc. Metabolic disorders in cancer cells further create a microenvironment including many kinds of oncometabolites that are conducive to the growth of cancer, thus forming a vicious circle. At the same time, exogenous metabolites can also affect the biological behavior of tumors. Here, we discuss the metabolite sensing mechanisms of the three major nutrients and their derivatives, as well as their abnormalities in the development of various cancers, and discuss the potential therapeutic targets based on metabolite-sensing signaling pathways to prevent the progression of cancer.

A Review of Gut Microbiota-Derived Metabolites in Tumor Progression and Cancer Therapy

Gut microbiota-derived metabolites are key hubs connecting the gut microbiome and cancer progression, primarily by remodeling the tumor microenvironment and regulating key signaling pathways in cancer cells and multiple immune cells. The use of microbial metabolites in radiotherapy and chemotherapy mitigates the severe side effects from treatment and improves the efficacy of treatment. Immunotherapy combined with microbial metabolites effectively activates the immune system to kill tumors and overcomes drug resistance. Consequently, various novel strategies have been developed to modulate microbial metabolites. Manipulation of genes involved in microbial metabolism using synthetic biology approaches directly affects levels of microbial metabolites, while fecal microbial transplantation and phage strategies affect levels of microbial metabolites by altering the composition of the microbiome. However, some microbial metabolites harbor paradoxical functions depending on the context (e.g., type of cancer). Furthermore, the metabolic effects of microorganisms on certain anticancer drugs such as irinotecan and gemcitabine, render the drugs ineffective or exacerbate their adverse effects. Therefore, a personalized and comprehensive consideration of the patient's condition is required when employing microbial metabolites to treat cancer. The purpose of this review is to summarize the correlation between gut microbiota-derived metabolites and cancer, and to provide fresh ideas for future scientific research.

Interplay between Phytochemicals and the Colonic Microbiota

Phytochemicals are natural compounds found in food ingredients with a variety of health-promoting properties. Phytochemicals improve host health through their direct systematic absorption into the circulation and modulation of the gut microbiota. The gut microbiota increases the bioactivity of phytochemicals and is a symbiotic partner whose composition and/or diversity is altered by phytochemicals and affects host health. In this review, the interactions of phytochemicals with the gut microbiota and their impact on human diseases are reviewed. We describe the role of intestinal microbial metabolites, including short-chain fatty acids, amino acid derivatives, and vitamins, from a therapeutic perspective. Next, phytochemical metabolites produced by the gut microbiota and the therapeutic effect of some selected metabolites are reviewed. Many phytochemicals are degraded by enzymes unique to the gut microbiota and act as signaling molecules in antioxidant, anti-inflammatory, anticancer, and metabolic pathways. Phytochemicals can ameliorate diseases by altering the composition and/or diversity of the gut microbiota, and they increase the abundance of some gut microbiota that produce beneficial substances. We also discuss the importance of investigating the interactions between phytochemicals and gut microbiota in controlled human studies.

Gut Microbiota in Colorectal Cancer: Biological Role and Therapeutic Opportunities

Colorectal cancer (CRC) is the second-leading cause of cancer-related deaths worldwide. While CRC is thought to be an interplay between genetic and environmental factors, several lines of evidence suggest the involvement of gut microbiota in promoting inflammation and tumor progression. Gut microbiota refer to the ~40 trillion microorganisms that inhabit the human gut. Advances in next-generation sequencing technologies and metagenomics have provided new insights into the gut microbial ecology and have helped in linking gut microbiota to CRC. Many studies carried out in humans and animal models have emphasized the role of certain gut bacteria, such as Fusobacterium nucleatum, enterotoxigenic Bacteroides fragilis, and colibactin-producing Escherichia coli, in the onset and progression of CRC. Metagenomic studies have opened up new avenues for the application of gut microbiota in the diagnosis, prevention, and treatment of CRC. This review article summarizes the role of gut microbiota in CRC development and its use as a biomarker to predict the disease and its potential therapeutic applications.

The Impact of Ellagitannins and Their Metabolites through Gut Microbiome on the Gut Health and Brain Wellness within the Gut-Brain Axis

Ellagitannins (ETs) are a large group of bioactive compounds found in plant-source foods, such as pomegranates, berries, and nuts. The consumption of ETs has often been associated with positive effects on many pathologies, including cardiovascular diseases, neurodegenerative syndromes, and cancer. Although multiple biological activities (antioxidant, anti-inflammatory, chemopreventive) have been discussed for ETs, their limited bioavailability prevents reaching significant concentrations in systemic circulation. Instead, urolithins, ET gut microbiota-derived metabolites, are better absorbed and could be the bioactive molecules responsible for the antioxidant and anti-inflammatory activities or anti-tumor cell progression. In this review, we examined the dietary sources, metabolism, and bioavailability of ETs, and analyzed the last recent findings on ETs, ellagic acid, and urolithins, their intestinal and brain activities, the potential mechanisms of action, and the connection between the ET microbiota metabolism and the consequences detected on the gut-brain axis. The current in vitro, in vivo, and clinical studies indicate that ET-rich foods, individual gut microbiomes, or urolithin types could modulate signaling pathways and promote beneficial health effects. A better understanding of the role of these metabolites in disease pathogenesis may assist in the prevention or treatment of pathologies targeting the gut-brain axis.

Main Determinants Affecting the Antiproliferative Activity of Stilbenes and Their Gut Microbiota Metabolites in Colon Cancer Cells: A Structure-Activity Relationship Study

trans-Resveratrol can be catabolized by the gut microbiota to dihydroresveratrol, 3,4'-dihydroxy-trans-stilbene, lunularin, and 4-hydroxydibenzyl. These metabolites can reach relevant concentrations in the colon. However, not all individuals metabolize RSV equally, as it depends on their RSV gut microbiota metabotype (i.e., lunularin producers vs. non-producers). However, how this microbial metabolism affects the cancer chemopreventive activity of stilbenes and their microbial metabolites is poorly known. We investigated the structure-antiproliferative activity relationship of dietary stilbenes, their gut microbial metabolites, and various analogs in human cancer (Caco-2 and HT-29) and non-tumorigenic (CCD18-Co) colon cells. The antiproliferative IC₅₀ values of pterostilbene, oxy-resveratrol, piceatannol, resveratrol, dihydroresveratrol, lunularin, 3,4'-dihydroxy-trans-stilbene, pinosylvin, dihydropinosylvin, 4-hydroxy-trans-stilbene, 4-hydroxydibenzyl, 3-hydroxydibenzyl, and 4-trans-stilbenemethanol were calculated. IC₅₀ values were correlated with 34 molecular characteristics by bi- and multivariate analysis. Little or no activity on CCD18-Co was observed, while Caco-2 was more sensitive than HT-29, which was explained by their different capacities to metabolize the compounds. Caco-2 IC₅₀ values ranged from 11.4 ± 10.1 μM (4-hydroxy-trans-stilbene) to 73.9 ± 13.8 μM (dihydropinosylvin). In HT-29, the values ranged from 24.4 ± 11.3 μM (4-hydroxy-trans-stilbene) to 96.7 ± 6.7 μM (4-hydroxydibenzyl). At their IC₅₀, most compounds induced apoptosis and arrested the cell cycle at the S phase, pterostilbene at G₂/M, while 4-hydroxy-trans-stilbene and 3,4'-dihydroxy-trans-stilbene arrested at both phases. Higher Connolly values (larger size) hindered the antiproliferative activity, while a lower pKa1 enhanced the activity in Caco-2, and higher LogP values (more hydrophobicity) increased the activity in HT-29. Reducing the styrene double bond in stilbenes was the most critical feature in decreasing the antiproliferative activity. These results (i) suggest that gut microbiota metabolism determines the antiproliferative effects of dietary stilbenes. Therefore, RSV consumption might exert different effects in individuals depending on their gut microbiota metabotypes associated with RSV metabolism, and (ii) could help design customized drugs with a stilbenoid and (or) dibenzyl core against colorectal cancer.

Urolithins: a Comprehensive Update on their Metabolism, Bioactivity, and Associated Gut Microbiota

Urolithins, metabolites produced by the gut microbiota from the polyphenols ellagitannins and ellagic acid, are discovered by the research group in humans almost 20 years ago. Pioneering research suggests urolithins as pleiotropic bioactive contributors to explain the health benefits after consuming ellagitannin-rich sources (pomegranates, walnuts, strawberries, etc.). Here, this study comprehensively updates the knowledge on urolithins, emphasizing the review of the literature published during the last 5 years. To date, 13 urolithins and their corresponding conjugated metabolites (glucuronides, sulfates, etc.) have been described and, depending on the urolithin, detected in different human fluids and tissues (urine, blood, feces, breastmilk, prostate, colon, and breast tissues). There has been a substantial advance in the research on microorganisms involved in urolithin production, along with the compositional and functional characterization of the gut microbiota associated with urolithins metabolism that gives rise to the so-called urolithin metabotypes (UM-A, UM-B, and UM-0), relevant in human health. The design of in vitro studies using physiologically relevant assay conditions (molecular forms and concentrations) is still a pending subject, making some reported urolithin activities questionable. In contrast, remarkable progress has been made in the research on the safety, bioactivity, and associated mechanisms of urolithin A, including the first human interventions.

Gut Microbiota and Tumor Immune Escape: A New Perspective for Improving Tumor Immunotherapy

The gut microbiota is a large symbiotic community of anaerobic and facultative aerobic bacteria inhabiting the human intestinal tract, and its activities significantly affect human health. Increasing evidence has suggested that the gut microbiome plays an important role in tumor-related immune regulation. In the tumor microenvironment (TME), the gut microbiome and its metabolites affect the differentiation and function of immune cells regulating the immune evasion of tumors. The gut microbiome can indirectly influence individual responses to various classical tumor immunotherapies, including immune checkpoint inhibitor therapy and adoptive immunotherapy. Microbial regulation through antibiotics, prebiotics, and fecal microbiota transplantation (FMT) optimize the composition of the gut microbiome, improving the efficacy of immunotherapy and bringing a new perspective and hope for tumor treatment.

Health functions and related molecular mechanisms of ellagitannin-derived urolithins

Ellagitannins are vital bioactive polyphenols that are widely distributed in a variety of plant-based foods. The main metabolites of ellagitannins are urolithins, and current research suggests that urolithins provide a variety of health benefits. This review focused on the role of the gut bacteria in the conversion of ellagitannins to urolithins. Based on the results of in vitro and in vivo studies, the health benefits of urolithins, including antioxidant, anti-inflammatory, anti-cancer, anti-obesity, anti-diabetic, anti-aging, cardiovascular protective, neuroprotective, kidney protective, and muscle mass protective effects, were thoroughly outlined, with a focus on their associated molecular mechanisms. Finally, we briefly commented on urolithins' safety. Overall, urolithins' diverse health benefits indicate the potential utilization of ellagitannins and urolithins in the creation of functional foods and nutraceuticals to treat and prevent some chronic diseases.

Recent Advances and Perspectives on the Health Benefits of Urolithin B, A Bioactive Natural Product Derived From Ellagitannins

Urolithin (Uro) B is a natural compound produced by gut bacteria from ingested ellagitannins (ETs) and ellagic acid (EA), complex polyphenols abundant in foods such as pomegranates, raspberries, blueberries and chestnuts. Uro B has recently garnered considerable attention owing to its wide range of nutraceutical effects and relatively high potency. According to several studies, Uro B prevents the development of hyperlipidemia, cardiovascular disease (CVD) and tumors due to its strong antioxidant and anti-inflammatory properties. Many reviews have systematically summarized the health benefits and pharmacological activities of ETs, EA and urolithins (especially Uro A) while available reviews or detailed summaries on the positive impact of Uro B are rarer. Here, we sought to review the pharmacological activity, mechanism of action, regulation of immune function and its associated diseases and preventive potential of Uro B to elucidate its function as a nutritional agent in humans.

The therapeutic potential of urolithin A for cancer treatment and prevention

BACKGROUND

Urolithin A is the metabolite of natural polyphenol ellagic acid and ellagitannins, generated by gut microbiota. Urolithin A is better absorbed in the gastrointestinal tract than its parent substances. Thus, the variable effects of ellagitannin-reach food (like pomegranate fruit, walnuts, tea, and others) on people's health might be linked with the differences in individual microbiota content. Urolithin A possesses various anti-inflammatory and anticancer effects, shown by in vivo and in vitro studies.

OBJECTIVE

In the current review, we consider anti-inflammatory and direct anticancer urolithin A effects as well as their molecular mechanisms, which might be the basement of clinical trials, estimating urolithin A anticancer effects.

CONCLUSION

Urolithin A attenuated the pro-inflammatory factors production (IL-6, IL-1β, NOS2 and others) in vitro studies. Oral urolithin A treatment caused prominent anticancer and anti-inflammatory action in various in vivo studies, including colitis rat model, carrageenan-induced paw edema mice model, models of pancreatic cancer, and models of obesity. The main molecular mechanisms of these effects might be the modulation of aryl hydrocarbon receptors, which antagonism may lead to decreasing of chronic inflammation. Other primary targets of urolithin A might be the processes of protein phosphorylation (for instance, it decreases the phosphorylation of protein kinase B) and p53 stabilization. Anti-inflammatory effects of urolithin A can be reached in physiologically relevant concentrations. This might be of vital importance for preventing immune suppression, associated with chronic inflammation in cancer. Considering the favorable urolithin A safety profile, it is the promising compound for cancer treatment and prevention.

Utility of Indian fruits in cancer prevention and treatment: Time to undertake translational and bedside studies

The World Health Organization predicts a 70% increase in cancer incidents in developing nations over the next decade, and it will be the second leading cause of death worldwide. Traditional plant-based medicine systems play an important role against various diseases and provide health care to a large section of the population in developing countries. Indigenous fruits and their bioactive compounds with beneficial effects like antioxidant, antiproliferative, and immunomodulatory are shown to be useful in preventing the incidence of cancer. India is one of the biodiversity regions and is native to numerous flora and fauna in the world. Of the many fruiting trees indigenous to India, Mango (Mangifera indica), Black plum (Eugenia jambolana or Syzygium jambolana), Indian gooseberry (Emblica officinalis or Phyllanthus emblica), kokum (Garcinia indica or Brindonia indica), stone apple or bael (Aegle marmelos), Jackfruit (Artocarpus heterophyllus), Karaunda (Carissa carandas) and Phalsa (Grewia asiatica), Monkey Jackfruit (Artocarpus lakoocha) and Elephant apple (Dillenia indica) have been shown to be beneficial in preventing cancer and in the treatment of cancer in validated preclinical models of study. In this review, efforts are also made to collate the fruits' anticancer effects and the important phytochemicals. Efforts are also made at emphasizing the underlying mechanism/s responsible for the beneficial effects in cancer prevention and treatment. These fruits have been a part of the diet, are non-toxic, and easily acceptable for human application. The plants and some of their phytochemicals possess diverse medicinal properties. The authors propose that future studies should be directed at detailed studies with various preclinical models of study with both composite fruit extract/juice and the individual phytochemicals. Additionally, translational studies should be planned with the highly beneficial, well-investigated and pharmacologically multifactorial amla to understand its usefulness as a cancer preventive in the high-risk population and as a supportive agent in cancer survivors. The outcome of both preclinical and clinical studies will be useful for patients, the healthcare fraternity, pharmaceutical, and agro-based sectors.

The role of key gut microbial metabolites in the development and treatment of cancer

In recent years, the role of gut microbial metabolites on the inhibition and progression of cancer has gained significant interest in anticancer research. It has been established that the gut microbiome plays a pivotal role in the development, treatment and prognosis of different cancer types which is often mediated through the gut microbial metabolites. For instance, gut microbial metabolites including bacteriocins, short-chain fatty acids and phenylpropanoid-derived metabolites have displayed direct and indirect anticancer activities through different molecular mechanisms. Despite the reported anticancer activity, some gut microbial metabolites including secondary bile acids have exhibited pro-carcinogenic properties. This review draws a critical summary and assessment of the current studies demonstrating the carcinogenic and anticancer activity of gut microbial metabolites and emphasises the need to further investigate the interactions of these metabolites with the immune system as well as the tumour microenvironment in molecular mechanistic and clinical studies.

Milk-Derived Exosomes as Nanocarriers to Deliver Curcumin and Resveratrol in Breast Tissue and Enhance Their Anticancer Activity

Dietary (poly)phenols are extensively metabolized, limiting their anticancer activity. Exosomes (EXOs) are extracellular vesicles that could protect polyphenols from metabolism. Our objective was to compare the delivery to breast tissue and anticancer activity in breast cancer cell lines of free curcumin (CUR) and resveratrol (RSV) vs. their encapsulation in milk-derived EXOs (EXO-CUR and EXO-RSV). A kinetic breast tissue disposition was performed in rats. CUR and RSV were analyzed using UPLC-QTOF-MS and GC-MS, respectively. Antiproliferative activity was tested in MCF-7 and MDA-MB-231 breast cancer and MCF-10A non-tumorigenic cells. Cell cycle distribution, apoptosis, caspases activation, and endocytosis pathways were determined. CUR and RSV peaked in the mammary tissue (41 ± 15 and 300 ± 80 nM, respectively) 6 min after intravenous administration of EXO-CUR and EXO-RSV, but not with equivalent free polyphenol concentrations. Nanomolar EXO-CUR or EXO-RSV concentrations, but not free CUR or RSV, exerted a potent antiproliferative effect on cancer cells with no effect on normal cells. Significant (p < 0.05) cell cycle alteration and pro-apoptotic activity (via the mitochondrial pathway) were observed. EXO-CUR and EXO-RSV entered the cells primarily via clathrin-mediated endocytosis, avoiding ATP-binding cassette transporters (ABC). Milk EXOs protected CUR and RSV from metabolism and delivered both polyphenols to the mammary tissue at concentrations compatible with the fast and potent anticancer effects exerted in model cells. Milk EXOs enhanced the bioavailability and anticancer activity of CUR and RSV by acting as Trojan horses that escape from cancer cells’ ABC-mediated chemoresistance.

Ellagic acid and intestinal microflora metabolite urolithin A: A review on its sources, metabolic distribution, health benefits, and biotransformation

Foods rich in ellagic tannins are first hydrolyzed into ellagic acid in the stomach and small intestine, and then converted into urolithins with high bioavailability by the intestinal flora. Urolithin has beneficially biological effects, it can induce adipocyte browning, improve cholesterol metabolism, inhibit graft tumor growth, relieve inflammation, and downregulate neuronal amyloid protein formation via the β3-AR/PKA/p38MAPK, ERK/AMPKα/SREBP1, PI3K/AKT/mTOR signaling pathways, and TLR4, AHR receptors. But differences have been reported in urolithin production capacity among different individuals. Thus, it is of great significance to explore the biological functions of urolithin, screen the strains responsible for biotransformation of urolithin, and explore the corresponding functional genes. Tannin acyl hydrolase can hydrolyze tannins into ellagic acid, and the genera Gordonibacter and Ellagibacter can metabolize ellagic acid into urolithins. Therefore, application of "single bacterium", "single bacterium + enzyme", and "microflora" can achieve biotransformation of urolithin A. In this review, the source and metabolic pathway of ellagic tannins, and the mechanisms of the biological function of a metabolite, urolithin A, are discussed. The current strategies of biotransformation to obtain urolithin A are expounded to provide ideas for further studies on the relationship between urolithin and human health.

Polyphenols as the Potential Disease-modifying Therapy in Cancer

BACKGROUND

Disease-modifying therapy in cancer can be defined as long-term treatment that has a beneficial outcome on the course of cancer, affecting the underlying pathophysiology. The anticancer potential of polyphenols is widely studied. However, there is a significant gap between experimental data obtained in vitro and in vivo and the current polyphenol role in cancer therapy.

OBJECTIVE

In this article, the reason for this inconsistency is discussed, which might be in the design of polyphenols clinical trials. The approach of long-term polyphenol disease-modifying therapy in cancer is encouraged.

CONCLUSION

As the physiologic concentrations of polyphenols are not sufficient for reaching the cytotoxic levels, the immune-modulatory effects and effects on cancer intrinsic signal transduction pathways should be considered in polyphenol clinical trials design. Such effects apparently can not cause the rapid regression of the disease. However, more likely, they can modulate the course of the disease, leading to favorable changes in the patient's condition in case of long-term treatment that can be considered to be cancer disease modification.

Ellagic acid ameliorates paraquat-induced liver injury associated with improved gut microbial profile

Paraquat, a widely used herbicide, causes environmental pollution, and liver injury in humans and animals. As a natural compound in fruits, ellagic acid (EA) shows anti-inflammatory and antioxidant effects. This study examines the beneficial effects of dietary EA against the paraquat-induced hepatic injury and further explores the underlying molecular mechanisms using a piglet model. Post-weaning piglets are fed basal diet supplemented with 50 mg/kg, 100 mg/kg, or 200 mg/kg EA for 3 weeks. At week 2, hepatic injury is induced by 4 mg/kg paraquat followed by 7 days recovery. EA supplementation significantly mitigates paraquat-induced hepatic fibrosis, steatosis, and high apoptotic rate. In agreement, EA supplementation reduces serum pro-inflammatory levels, ameliorates inflammatory cells infiltration into hepatic tissue, which are associated with suppressed NF-κB signaling during paraquat exposure. In addition, EA supplementation significantly improves activities of antioxidative enzymes which were correlated with activated Nrf2/Keap 1 signaling during paraquat exposure. Furthermore, EA supplementation restores cecal microbial community during paraquat exposure. The protective effect of EA is strongly linked with increased relative abundance of Lactobacillus reuteri and Lactobacillus amylovorus. Taken together, EA supplementation effectively reduced the occurrence of hepatic oxidative damage and inflammation induced by paraquat through modulating cecal microbial communities, which provides a novel nutritional therapeutic strategy for hepatic injury.

Main drivers of (poly)phenol effects on human health: metabolite production and/or gut microbiota-associated metabotypes?

Despite the high human interindividual variability in response to (poly)phenol consumption, the cause-and-effect relationship between some dietary (poly)phenols (flavanols and olive oil phenolics) and health effects (endothelial function and prevention of LDL oxidation, respectively) has been well established. Most of the variables affecting this interindividual variability have been identified (food matrix, gut microbiota, single-nucleotide-polymorphisms, etc.). However, the final drivers for the health effects of (poly)phenol consumption have not been fully identified. At least partially, these drivers could be (i) the (poly)phenols ingested that exert their effect in the gastrointestinal tract, (ii) the bioavailable metabolites that exert their effects systemically and/or (iii) the gut microbial ecology associated with (poly)phenol metabolism (i.e., gut microbiota-associated metabotypes). However, statistical associations between health effects and the occurrence of circulating and/or excreted metabolites, as well as cross-sectional studies that correlate gut microbial ecologies and health, do not prove a causal role unequivocally. We provide a critical overview and perspective on the possible main drivers of the effects of (poly)phenols on human health and suggest possible actions to identify the putative actors responsible for the effects.

Targeting cellular senescence in cancer by plant secondary metabolites: A systematic review

Senescence suppresses tumor growth, while also developing a tumorigenic state in the nearby cells that is mediated by senescence-associated secretory phenotypes (SASPs). The dual function of cellular senescence stresses the need for identifying multi-targeted agents directed towards the promotion of cell senescence in cancer cells and suppression of the secretion of pro-tumorigenic signaling mediators in neighboring cells. Natural secondary metabolites have shown favorable anticancer responses in recent decades, as some have been found to target the senescence-associated mediators and pathways. Furthermore, phenolic compounds and polyphenols, terpenes and terpenoids, alkaloids, and sulfur-containing compounds have shown to be promising anticancer agents through the regulation of paracrine and autocrine pathways. Plant secondary metabolites are potential regulators of SASPs factors that suppress tumor growth through paracrine mediators, including growth factors, cytokines, extracellular matrix components/enzymes, and proteases. On the other hand, ataxia-telangiectasia mutated, ataxia-telangiectasia and Rad3-related, extracellular signal-regulated kinase/mitogen-activated protein kinase, phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin, nuclear factor-κB, Janus kinase/signal transducer and activator of transcription, and receptor tyrosine kinase-associated mediators are main targets of candidate phytochemicals in the autocrine senescence pathway. Such a regulatory role of phytochemicals on senescence-associated pathways are associated with cell cycle arrest and the attenuation of apoptotic/inflammatory/oxidative stress pathways. The current systematic review highlights the critical roles of natural secondary metabolites in the attenuation of autocrine and paracrine cellular senescence pathways, while also elucidating the chemopreventive and chemotherapeutic capabilities of these compounds. Additionally, we discuss current challenges, limitations, and future research indications.

A mechanistic insight into the biological activities of urolithins as gut microbial metabolites of ellagitannins

Urolithins are the gut metabolites produced from ellagitannin-rich foods such as pomegranates, tea, walnuts, as well as strawberries, raspberries, blackberries, and cloudberries. Urolithins are of growing interest due to their various biological activities including cardiovascular protection, anti-inflammatory activity, anticancer properties, antidiabetic activity, and antiaging properties. Several studies mostly based on in vitro and in vivo experiments have investigated the potential mechanisms of urolithins which support the beneficial effects of urolithins in the treatment of several diseases such as Alzheimer's disease, type 2 diabetes mellitus, liver disease, cardiovascular disease, and various cancers. It is now obvious that urolithins can involve several cellular mechanisms including inhibition of MDM2-p53 interaction, modulation of mitogen-activated protein kinase pathway, and suppressing nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activity. Antiaging activity is the most appealing and probably the most important property of urolithin A that has been investigated in depth in recent studies, owing to its unique effects on activation of mitophagy and mitochondrial biogenesis. A recent clinical trial showed that urolithin A is safe up to 2,500 mg/day and can improve mitochondrial biomarkers in elderly patients. Regarding the importance of mitochondria in the pathophysiology of many diseases, urolithins merit further research especially in clinical trials to unravel more aspects of their clinical significance. Besides the nutritional value of urolithins, recent studies proved that urolithins can be used as pharmacological agents to prevent or cure several diseases. Here, we comprehensively review the potential role of urolithins as new therapeutic agents with a special focus on the molecular pathways that have been involved in their biological effects. The pharmacokinetics of urolithins is also included.

Punicalagin in Cancer Prevention-Via Signaling Pathways Targeting

The extract of pomegranate (Punica granatum) has been applied in medicine since ancient times due to its broad-spectrum health-beneficial properties. It is a rich source of hydrolyzable tannins and anthocyanins, exhibiting strong antioxidative, anti-inflammatory, and antineoplastic properties. Anticancer activities of pomegranate with reference to modulated signaling pathways in various cancer diseases have been recently reviewed. However, less is known about punicalagin (Pug), a prevailing compound in pomegranate, seemingly responsible for its most beneficial properties. In this review, the newest data derived from recent scientific reports addressing Pug impact on neoplastic cells are summarized and discussed. Its attenuating effect on signaling circuits promoting cancer growth and invasion is depicted. The Pug-induced redirection of signal-transduction pathways from survival and proliferation into cell-cycle arrest, apoptosis, senescence, and autophagy (thus compromising neoplastic progression) is delineated. Considerations presented in this review are based mainly on data obtained from in vitro cell line models and concern the influence of Pug on human cervical, ovarian, breast, lung, thyroid, colorectal, central nervous system, bone, as well as other cancer types.

Antiproliferative Effect of Colonic Fermented Phenolic Compounds from Jaboticaba (Myrciaria trunciflora) Fruit Peel in a 3D Cell Model of Colorectal Cancer

Jaboticaba is a Brazilian native berry described as a rich source of phenolic compounds (PC) with health promoting effects. PC from jaboticaba peel powder (JPP) have low intestinal bio-accessibility and are catabolized by gut microbiota. However, the biological implication of PC-derived metabolites produced during JPP digestion remains unclear. This study aimed to evaluate the antiproliferative effects of colonic fermented JPP (FJPP) in a 3D model of colorectal cancer (CRC) composed by HT29 spheroids. JPP samples fermented with human feces during 0, 2, 8, 24 or 48 h were incubated (10,000 µg mL⁻¹) with spheroids, and cell viability was assessed after 72 h. Chemometric analyses (cluster and principal component analyses) were used to identify the main compounds responsible for the bioactive effect. The antiproliferative effect of FJPP in the CRC 3D model was increased between 8 h and 24 h of incubation, and this effect was associated with HHDP-digalloylglucose isomer and dihydroxyphenyl-γ-valerolactone. At 48 h of fermentation, the antiproliferative effect of FJPP was negligible, indicating that the presence of urolithins did not improve the bioactivity of JPP. These findings provide relevant knowledge on the role of colonic microbiota fermentation to generate active phenolic metabolites from JPP with positive impact on CRC.

Urolithins: The Gut Based Polyphenol Metabolites of Ellagitannins in Cancer Prevention, a Review

Cancer as a disease continues to ravage the world population without regard to sex, age, and race. Due to the growing number of cases worldwide, cancer exerts a significant negative impact on global health and the economy. Interestingly, chemotherapy has been used over the years as a therapeutic intervention against cancer. However, high cost, resistance, and toxic by-effects to treatment have overshadowed some of its benefits. In recent times, efforts have been ongoing in searching for anticancer therapeutics of plant origin, focusing on polyphenols. Urolithins are secondary polyphenol metabolites derived from the gut microbial action on ellagitannins and ellagic acid-rich foods such as pomegranate, berries, and nuts. Urolithins are emerging as a new class of anticancer compounds that can mediate their cancer-preventive activities through cell cycle arrest, aromatase inhibition, induction of apoptosis, tumor suppression, promotion of autophagy, and senescence, transcriptional regulation of oncogenes, and growth factor receptors. In this review, we discussed the growing shreds of evidence supporting these secondary phenolic metabolites' anticancer properties. Furthermore, we have pointed out some of the future directions needed to establish urolithins as anticancer agents.

Disposition of Dietary Polyphenols in Breast Cancer Patients' Tumors, and Their Associated Anticancer Activity: The Particular Case of Curcumin

SCOPE

Some polyphenol-derived metabolites reach human breast cancer (BC) tissues at concentrations that induce cell senescence. However, this is unknown for isoflavones, curcuminoids, and lignans. Here, their metabolic profiling in normal (NT) and malignant (MT) mammary tissues of newly-diagnosed BC patients and the tissue-occurring metabolites' anticancer activity are evaluated.

METHODS AND RESULTS

Patients (n = 26) consumed 3 capsules/day (turmeric, red clover, and flaxseed extracts plus resveratrol; 296.4 mg phenolics/capsule) from biopsy-confirmed diagnosis to surgery (5 ± 2 days) or did not consume capsules (n = 13). NT and MT, blood, and urine are analyzed by UPLC-QTOF-MS using targeted metabolomics. Anticancer activity was tested in MCF-7 and MDA-MB-231 BC cells. Mainly phase-II metabolites were detected (108, 84, 49, and 47 in urine, plasma, NT, and MT, respectively). Total metabolite concentrations reached 10.7 ± 11.1 and 2.5 ± 2.4 µmol L^-1 in NT and MT, respectively. Free curcumin, but not its glucuronide, was detected in the tissues (1.1 ± 1.8 and 0.2 ± 0.2 µmol L^-1 in NT and MT, respectively). Breast tissue-occurring metabolites' antiproliferation was mainly exerted in p53-wild-type MCF-7 cells by curcuminoids through cell cycle arrest, senescence, and apoptosis induction via p53/p21 induction, while isoflavone-derived metabolites exerted estrogenic-like activity.

CONCLUSION

Curcuminoids could be coadjuvants that might help fight BC upon regular consumption.

Ellagic acid and urolithin A modulate the immune response in LPS-stimulated U937 monocytic cells and THP-1 differentiated macrophages

Dietary polyphenols are subjected, following ingestion, to an extensive metabolism, and the molecules that act at the cellular and tissue level will be, most likely, metabolites rather than native polyphenols. The mechanisms behind the positive effects exerted by polyphenols are not yet completely elucidated, since most in vitro studies use unmetabolised polyphenols rather than the metabolites present in the body. The aim of this study was to investigate and compare the potential effect of phenolic metabolites on the immune response using U937 monocyte and THP-1 macrophage cell cultures. Of the 16 metabolites tested, urolithins (Uro), and Uro A, in particular were the most potent, showing a modest increase in basal NF-κB activity and a reduction in lipopolysaccaride (LPS)-induced NF-κB activity, gene expression and secretion of pro-inflammatory cytokines. Protocatechuic acid and its sulfate/glucuronide metabolites reduced LPS-induced NF-κB activity, but not IL-6 and TNF-α cytokine secretion. Interestingly, both ellagic acid and its metabolite Uro A had immunomodulating effects, although they regulated the immune response differently, and both reduced LPS-induced NF-κB activity in U937 cells. However, while Uro A dramatically reduced IL-6 and IL-10 mRNA expression, no effect could be observed with ellagic acid. In THP-1 cells, treatment with ellagic acid dramatically reduced the expression of Toll-like receptor 4, while Uro A had no effect. The dual role observed for Uro A, showing both a modest increase in basal NF-κB activity and a reduction in LPS-induced NF-κB activity, as well as a reduction in LPS-induced pro-inflammatory cytokine secretion, makes this metabolite particularly interesting for further studies in animals and humans.

Dysbiosis, malnutrition and enhanced gut-lung axis contribute to age-related respiratory diseases

Older people are at an increased risk of developing respiratory diseases such as chronic obstructive pulmonary diseases, asthma, idiopathic pulmonary fibrosis or lung infections. Susceptibility to these diseases is partly due to the intrinsic ageing process, characterized by genomic, cellular and metabolic hallmarks and immunosenescence, and is associated with changes in the intestinal microbiota. Importantly, in the lungs, ageing is also associated with a dysbiosis and loss of resilience of the resident microbiota and alterations of the gut-lung axis. Notably, as malnutrition is often observed in the elderly, nutrition is one of the most accessible modifiable factors affecting both senescence and microbiota. This article reviews the changes affecting the lung and its resident microbiota during ageing, as well as the interconnections between malnutrition, senescence, microbiota, gut-lung axis and respiratory health. As the communication along the gut-lung axis becomes more permissive with ageing, this review also explores the evidence that the gut and lung microbiota are key players in the maintenance of healthy lungs, and as such, are potential targets for nutrition-based preventive strategies against lung disease in elderly populations.

AhR and Cancer: From Gene Profiling to Targeted Therapy

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that has been shown to be an essential regulator of a broad spectrum of biological activities required for maintaining the body’s vital functions. AhR also plays a critical role in tumorigenesis. Its role in cancer is complex, encompassing both pro- and anti-tumorigenic activities. Its level of expression and activity are specific to each tumor and patient, increasing the difficulty of understanding the activating or inhibiting roles of AhR ligands. We explored the role of AhR in tumor cell lines and patients using genomic data sets and discuss the extent to which AhR can be considered as a therapeutic target.

Acorn flour properties depending on the production method and laboratory baking test results: A review

Acorns, the fruit of the oak, have long been an important source of food in different cultures around the world. Despite their long culinary tradition, they have become under-appreciated. Due to their high starch content, acorns are mainly used for flour production, and acorn flour is considered as a replacement for cereal flour in a wide range of applications in food production. This study reviewed the published literature concerning acorn flour production and composition as well as the possibility of using acorn flour in the most popular flour-based products such as bread, cake, and cookies. The study also presents the advantages resulting from acorn flour incorporation to the human diet and acorn flour influence on the quality of bread and pastry products. This review found that acorn flour is characterized by a lack of gluten proteins and a high content of fiber and minerals as well as the presence of polyphenols with antioxidant properties. However, negative impact of its larger amount on the dough rheological features and product physical properties has been emphasized in many studies. The researchers recommend the incorporation of acorn flour up to a level of 15% in formulating composite flour for bread production. However, the literature data indicates that acorn flour substitution for pastry production depends on the product type and ranges from 10 to even 60%. It is also highlighted that the application of acorn flour into gluten-free products is particularly favorable from a nutritional point of view.

Ellagic Acid-Derived Urolithins as Modulators of Oxidative Stress

Oxidative stress is a state of excess of prooxidative species relative to the antioxidant defenses (enzymatic and nonenzymatic) in a living organism. The consequence of this imbalance is damage of the major cellular macromolecules (carbohydrates, lipids, proteins, and DNA), which further leads to a gradual loss of tissue and organ function. It has been shown that oxidative stress plays an important role in the pathogenesis of many chronic diseases (cardiovascular, metabolic, and neurodegenerative diseases and cancer) and in the process of aging. Thus, many strategies to combat oxidative stress have been proposed and tested. In this context, food rich in antioxidants has received great attention. Pomegranate, berries, and walnuts have been recognized as “superfood” particularly for their cardioprotective effects. The common characteristic of these foods is the high content of ellagitannins. Since tannins are not bioavailable, they have been neglected in nutrition science and even considered antinutrients for a long time. However, this view has changed dramatically once it was recognized that ellagic acid, released from ellagitannins in the gastrointestinal system, is further metabolized by colonic microbiota to bioavailable compounds—known as urolithins. Thus, urolithins (3,4-benzocoumarin derivatives) have emerged as novel natural bioactive compounds and are now the focus of extensive investigations. So far, urolithins were shown to be powerful modulators of oxidative stress and agents with potential anti-inflammatory, antiproliferative, and antiaging properties. Furthermore, a few synthetic derivatives of urolithins were recognized as lead compounds for new drug development. Available data on urolithin synthesis, physicochemical and pharmacokinetic characteristics, biological activity, and safety will be presented in this review.

Potential of the ellagic acid-derived gut microbiota metabolite - Urolithin A in gastrointestinal protection

Urolithin A (UA) is a metabolic compound generated during the biotransformation of ellagitannins by the intestinal bacteria. The physiologically relevant micromolar concentrations of UA, achieved in the plasma and gastrointestinal tract (GI) after consumption of its dietary precursors, have been revealed to offer GI protection. The health benefit has been demonstrated to be principally related to anticancer and anti-inflammatory effects. UA has been shown to possess the capability to regulate multiple tumor and inflammatory signaling pathways and to modulate enzyme activity, including those involved in carcinogen biotransformation and antioxidant defense. The purpose of this review is to gather evidence from both in vitro and in vivo studies showing the potential of UA in GI protection alongside suggested mechanisms by which UA can protect against cancer and inflammatory diseases of the digestive tract. The data presented herein, covering both studies on the pure compound and in vivo generated UA form its natural precursor, support the potential of this metabolite in treatment interventions against GI ailments.