Urolithins, gut microbiota-derived metabolites of ellagitannins, inhibit LPS-induced inflammation in RAW 264.7 murine macrophages

Urolithin B inhibits the differentiation of M1 macrophages and relieves the inflammation around the implants under osteoporosis via down-regulating the phosphorylation of VEGFR2

The inflammation causes the destroyed osseointegration at the implant-bone interface, significantly increasing the probability of implant loosening in osteoporotic patients. Currently, inhibiting the differentiation of M1 macrophages and the inflammatory response could be a solution to stabilize the microenvironment of implants. Interestingly, some natural products have anti-inflammatory and anti-polarization effects, which could be a promising candidate for stabilizing the implants' microenvironment in osteoporotic patients. This research aims to explore the inhibitory effect of Urolithin B(UB) on macrophage M1 polarization, which ameliorates inflammation, thus alleviating implant instability. We established an osteoporosis mouse model of implant loosening. The mouse tissues were taken out for morphological analysis, staining analysis, and bone metabolic index analysis. In in vitro experiments, RAW264.7 cells were polarized to M1 macrophages using lipopolysaccharide (LPS) and analyzed by immunofluorescence (IF) staining, Western blot (WB), and flow cytometry. The CSP100 plus chip experiments were used to explore the potential mechanisms behind the inhibiting effects of UB. Through observation of these experiments, UB can improve the osseointegration between the implants and femurs in osteoporotic mice and enhance the stability of implants. The UB can inhibit the differentiation of M1 macrophages and local inflammation via inhibiting the phosphorylation of VEGFR2, which can be further proved by the weakened inhibited effects of UB in macrophages with lentivirus-induced overexpression of VEGFR2. Overall, UB can specifically inhibit the activation of VEGFR2, alleviate local inflammation, and improve the stability of implants in osteoporotic mice.

Urolithin A, induces apoptosis and autophagy crosstalk in Oral Squamous Cell Carcinoma via mTOR /AKT/ERK1/2 pathway

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy in the world with an alarming rate of mortality. Despite the advancement in treatment strategies and drug developments, the overall survival rate remains poor. Therefore, it is imperative to develop alternative or complimentary anti cancer drugs with minimum off target effects. Urolithin A, a microbial metabolite of ellagic acid and ellagitannins produced endogenously by human gut micro biome is considered to have anti-cancerous activity. However anti tumorigenic effect of urolithin A in OSCC is yet to be elucidated. In this study, we examined whether urolithin A inhibits cell growth and induces both apoptosis and autophagy dependent cell death in OSCC cell lines.

PURPOSE

The present study aims to evaluate the potential of urolithin A to inhibit OSCC and its regulatory effect on OSCC proliferation and invasion in vitro and in vivo mouse models.

METHODS

We evaluated whether urolithin A could induce cell death in OSCC in vitro and in vivo mouse models.

RESULTS

Flow cytometric and immunoblot analysis on Urolithin A treated OSCC cell lines revealed that urolithin A markedly induced cell death of OSCC via the induction of endoplasmic reticulum stress and subsequent inhibition of AKT and mTOR signaling as evidenced by decreased levels of phosphorylated mTOR and 4EBP1. This further revealed a possible cross talk between apoptotic and autophagic signaling pathways. In vivo study demonstrated that urolithin A treatment reduced tumor size and showed a decrease in mTOR, ERK1/2 and Akt levels along with a decrease in proliferation marker, Ki67. Taken together, in vitro as well as our in vivo data indicates that urolithin A is a potential anticancer agent and the inhibition of AKT/mTOR/ERK signalling is crucial in Urolithin A induced growth suppression in oral cancer.

CONCLUSION

Urolithin A exerts its anti tumorigenic activity through the induction of apoptotic and autophagy pathways in OSCC. Our findings suggest that urolithin A markedly induced cell death of oral squamous cell carcinoma via the induction of endoplasmic reticulum stress and subsequent inhibition of AKT and mTOR signaling as evidenced by decreased levels of phosphorylated mTOR and 4EBP1. Urolithin A remarkably suppressed tumor growth in both in vitro and in vivo mouse models signifying its potential as an anticancer agent in the prevention and treatment of OSCC. Henceforth, our findings provide a new insight into the therapeutic potential of urolithin A in the prevention and treatment of OSCC.

Urolithin A suppresses NLRP3 inflammasome activation by inhibiting the generation of reactive oxygen species and prevents monosodium urate crystal-induced peritonitis

The NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome triggers the maturation of interleukin-1β (IL-1β) and is implicated in the pathogenesis of various inflammatory diseases. Urolithin A, a gut microbial metabolite of ellagic acid, reportedly exerts antiinflammatory effects in vitro and in vivo. However, whether urolithin A suppresses NLRP3 inflammasome activation is unclear. In this study, urolithin A inhibited the cleavage of NLRP3 inflammasome agonist-induced caspase-1, maturation of IL-1β, and activation of pyroptosis in lipopolysaccharide-primed mouse bone marrow-derived macrophages. Urolithin A reduced generation of intracellular and mitochondrial reactive oxygen species (ROS) and restricted the interaction between thioredoxin-interacting protein and NLRP3, which attenuated NLRP3 inflammasome activation. Urolithin A administration prevented monosodium urate-induced peritonitis in mice. Collectively, these findings indicate that urolithin A suppresses NLRP3 inflammasome activation, at least partially, by repressing the generation of intracellular and mitochondrial ROS.

Increased Glycolytic Activity Is Part of Impeded M1(LPS) Macrophage Polarization in the Presence of Urolithin A

Urolithin A is a gut metabolite of ellagitannins and reported to confer health benefits, e.g., by increased clearance of damaged mitochondria by macroautophagy or curbed inflammation. One targeted cell type are macrophages, which are plastic and able to adopt pro- or anti-inflammatory polarization states, usually assigned as M1 and M2 macrophages, respectively. This flexibility is tightly coupled to characteristic shifts in metabolism, such as increased glycolysis in M1 macrophages, and protein expression upon appropriate stimulation. This study aimed at investigating whether the anti-inflammatory properties of U: rolithin A may be driven by metabolic alterations in cultivated murine M1(lipopolysaccharide) macrophages. Expression and extracellular flux analyses showed that urolithin A led to reduced il1β, il6, and nos2 expression and boosted glycolytic activity in M1(lipopolysaccharide) macrophages. The pro-glycolytic feature of UROLITHIN A: occurred in order to causally contribute to its anti-inflammatory potential, based on experiments in cells with impeded glycolysis. Mdivi, an inhibitor of mitochondrial fission, blunted increased glycolytic activity and reduced M1 marker expression in M1(lipopolysaccharide/UROLITHIN A: ), indicating that segregation of mitochondria was a prerequisite for both actions of UROLITHIN A: . Overall, we uncovered a so far unappreciated metabolic facet within the anti-inflammatory activity of UROLITHIN A: and call for caution about the simplified notion of increased aerobic glycolysis as an inevitably proinflammatory feature in macrophages upon exposure to natural products.

Cancer-Stem-Cell Phenotype-Guided Discovery of a Microbiota-Inspired Synthetic Compound Targeting NPM1 for Leukemia

The human microbiota plays an important role in human health and disease, through the secretion of metabolites that regulate key biological functions. We propose that microbiota metabolites represent an unexplored chemical space of small drug-like molecules in the search of new hits for drug discovery. Here, we describe the generation of a set of complex chemotypes inspired on selected microbiota metabolites, which have been synthesized using asymmetric organocatalytic reactions. Following a primary screening in CSC models, we identified the novel compound UCM-13369 (4b) whose cytotoxicity was mediated by NPM1. This protein is one of the most frequent mutations of AML, and NPM1-mutated AML is recognized by the WHO as a distinct hematopoietic malignancy. UCM-13369 inhibits NPM1 expression, downregulates the pathway associated with mutant NPM1 C+, and specifically recognizes the C-end DNA-binding domain of NPM1 C+, avoiding the nucleus-cytoplasm translocation involved in the AML tumorological process. The new NPM1 inhibitor triggers apoptosis in AML cell lines and primary cells from AML patients and reduces tumor infiltration in a mouse model of AML with NPM1 C+ mutation. The disclosed phenotype-guided discovery of UCM-13369, a novel small molecule inspired on microbiota metabolites, confirms that CSC death induced by NPM1 inhibition represents a promising therapeutic opportunity for NPM1-mutated AML, a high-mortality disease.

Synthesis of urolithin derivatives and their anti-inflammatory activity

Two series of urolithin derivatives, totally 38 compounds, were synthesized. Their anti-inflammatory activity was investigated by detecting the inhibitory effects on the expression of TNF-α in bone marrow-derived macrophages (BMDMs), showing that 24 of 38 ones reduced the expression of TNF-α. Compound B2, the ring C opened derivative of urolithin B with a butoxycarbonyl substitution in ring A, showed the strongest inhibitory activity compared with that of indomethacin. Furthermore, B2 treatment decreased the expression of pro-inflammatory factors IL-1β, IL-6, iNOS and COX-2. Mechanically, the anti-inflammatory effect of B2 was related to the inhibition of NF-κB signaling pathway. These results clearly illustrated that B2 hold potential for application as an anti-inflammatory agent. The present study provided a viable approach to modify the gut metabolites for anti-inflammatory drug development.

Urolithin A Prevents Sleep-deprivation-induced Neuroinflammation and Mitochondrial Dysfunction in Young and Aged Mice

Sleep deprivation (SD) has reached epidemic proportions worldwide and negatively affects people of all ages. Cognitive impairment induced by SD involves neuroinflammation and mitochondrial dysfunction, but the underlying mechanisms are largely unknown. Urolithin A (UA) is a natural compound that can reduce neuroinflammation and improve mitochondrial health, but its therapeutic effects in a SD model have not yet been studied. Young (3-months old) and aged (12-months old) mice were sleep deprived for 24 h, and UA (2.5 mg/kg or 10 mg/kg) was injected intraperitoneally for 7 consecutive days before the SD period. Immunofluorescent staining, western blotting, and RT-PCR were employed to evaluate levels of proteins involved in neuroinflammation and mitochondrial function. Transmission electron microscope and Golgi-Cox staining were used to evaluate mitochondrial and neuronal morphology, respectively. Finally, contextual fear conditioning and the Morris water maze test were conducted to assess hippocampal learning and memory. In the hippocampus of young (3 months-old) and aged (12 months-old) mice subjected to 24 h SD, pretreatment with UA prevented the activation of microglia and astrocytes, NF-κB-NLRP3 signaling and IL-1β, IL6, TNF-α cytokine production, thus ameliorating neuroinflammation. Furthermore, UA also attenuated SD-induced mitochondrial dysfunction, normalized autophagy and mitophagy and protected hippocampal neuronal morphology. Finally, UA prevented SD-induced hippocampal memory impairment. Cumulatively, the results show that UA imparts cognitive protection by reducing neuroinflammation and enhancing mitochondrial function in SD mice. This suggests that UA shows promise as a therapeutic for the treatment of SD-induced neurological disorders.

Skin microbiota metabolism of natural products from comfrey root (Symphytum officinale L.)

ETHNOPHARMACOLOGICAL RELEVANCE

Comfrey root (Symphytum officinale L., Boraginaceae) has been used in folk medicine for a long time to treat different diseases. It is recommended for swellings, phlebitis, contusions, gastro-duodenal ulcers, respiratory diseases, and metrorrhagia. Currently, preparations from S. officinale are only topically used due to its wound-healing effects, and for reducing inflammation and the treatment of broken bones, tendon damage, painful joints and muscles. Although it is a widespread plant material, little is known about the interaction of externally applied preparations of comfrey with the human skin microbiome.

AIM OF THE STUDY

The study aims to determine the interaction between human skin microbiota and the comfrey root extracts, by monitoring the biotransformation of the constituents present in the extract and evaluating changes in the population of the skin microbiota in an ex vivo setting.

MATERIAL AND METHODS

The comfrey root extract was incubated with the human skin microbiota from ten healthy donors. The UHPLC-DAD-MSn analysis determined the composition of the raw extract and the microbial metabolites. Bacterial genomic DNA was extracted and examined by amplification sequencing of the 16S rDNA to determine changes in the bacterial composition.

RESULTS

The hydroethanolic extract of comfrey root primarily consists of phenolic acids, pyrrolizidine alkaloids, and their derivatives, and lignans. The natural products present in the extract underwent biodegradation by the skin microbiota, leading to the formation of smaller molecules. It was observed that the skin microbial metabolism primarily focused on modifying the derivatives of pyrrolizidine alkaloids. It resulted in the production of deacetylated and deesterificated compounds. However, it did not lead to the conversion of these compounds into free alkaloids.

CONCLUSIONS

The microbiota-triggered biotransformation of the comfrey root extract was observed. A few N-oxides were metabolized to deacetylated and deesterificated forms in ex vivo conditions. It suggests that the intermittent external applications of comfrey preparations perchance are unlikely to pose a substantial risk. While it even may serve as a potential factor influencing the extract activity in treating skin diseases.

Urolithin B alleviates Helicobacter pylori-induced inflammation and oxidative stress in mice

BACKGROUND

Helicobacter pylori is one of the most common chronic bacterial infections. Active eradication of H. pylori infection is rare due to the fact that most infected patients are asymptomatic and the use of large amounts of antibiotics in eradication therapy leads to severe side effects. Urolithin B (UB) is an additional major intestinal metabolite of ellagic acid (EA), which has been shown to possess anti-inflammatory, antioxidant, and antiapoptotic biological activities. Preventing the incidence of H. pylori-related gastric disease and reducing the damage to the host by H. pylori is a current approach to control H. pylori infection. In this study, we explored the effect of UB on H. pylori infection.

MATERIALS AND METHODS

The effects of UB on inflammation and oxidative stress induced by H. pylori in vivo and in vitro were investigated by qPCR, ELISA, HE staining, IHC staining, etc. RESULTS: UB reduced the adhesion and colonization of H. pylori and improved H. pylori-induced inflammation and oxidative stress in vivo and in vitro. Moreover, UB had better anti-inflammatory and antioxidant effects than clarithromycin (CLR) and metronidazole (MET). In addition to inhibiting the secretion of CagA, UB reduced tissue damage by H. pylori infection.

CONCLUSIONS

UB was effective in improving damage caused by H. pylori.

Urolithin C reveals anti-NAFLD potential via AMPK-ferroptosis axis and modulating gut microbiota

The pharmacology of urolithin C (UroC) on non-alcoholic fatty liver disease (NAFLD) is largely undetermined. We sought to investigate the potential for NAFLD improvement by administration of UroC and the underlying mechanisms. We verified the therapeutic effect of UroC on choline-deficient amino acid-defined high fat diet (CDAHFD) induced NAFLD mice via evaluating NAFLD activity score (NAS), AST, ALT, hepatic phosphorylated AMPK, and 4-hydroxynonenal. Oleic acid-induced AML12 cell was appraised by oil red staining and western blotting to explore the effect and mechanism of UroC in vitro. Transcriptional regulation of UroC was explored by liver RNA sequencing, gut microbiota composition was explored by 16SrRNA sequencing, and colorectal tight junctional proteins were detected by western blotting and immunohistochemistry. The detrimental effects of CDAHFD included the increased liver index, AST, ALT, hepatic 4-hydroxynonenal, impaired intestinal mucosal barrier, and most importantly, pathological damage in liver. Oral administration of UroC largely protected against these harmful alterations. Remarkably, both RNA sequencing and western blotting results indicated an activation in hepatic AMPK signaling pathway which was thought to inhibit ferroptosis response to UroC in vivo, while no change were found in AMPK-ferroptosis axis response to UroC in oleic acid-induced AML12 cells, hinted an indispensable linkage between UroC and hepatic AMPK, presumably the gut-liver axis. Furthermore, UroC could neither alleviate lipid deposition nor inhibit ferroptosis in vitro. The 16SrRNA showed UroC partially counteracted the dysbiosis induced by CDAHFD. Specifically, UroC reversed the elevated proportion of Firmicutes/Bacteroidota and enhanced the level of Parabacteroides goldsteinii and Lactobacillus vaginalis, which played a beneficial role in metabolic disorders. Oral administration of Urolithin C protected against the detrimental impact of CDAHFD via regulating AMPK-ferroptosis axis, maintaining intestinal mucosal barrier and counteracting gut dysbiosis.

Crosstalk between dietary pomegranate and gut microbiota: evidence of health benefits

Gut microbiota (GM) is an invisible organ that plays an important role in human health. Increasing evidence suggests that polyphenols in pomegranate (punicalagin, PU) could serve as prebiotics to modulate the composition and function of GM. In turn, GM transform PU into bioactive metabolites such as ellagic acid (EA) and urolithin (Uro). In this review, the interplay between pomegranate and GM is thoroughly described by unveiling a dialog in which both actors seem to affect each other's roles. In a first dialog, the influence of bioactive compounds from pomegranate on GM is described. The second act shows how the GM biotransform pomegranate phenolics into Uro. Finally, the health benefits of Uro and that related molecular mechanism are summarized and discussed. Intake of pomegranate promotes beneficial bacteria in GM (e.g. Lactobacillus spp., Bifidobacterium spp.) while reducing the growth of harmful bacteria (e.g. Bacteroides fragilis group, Clostridia). Akkermansia muciniphila, and Gordonibacter spp., among others, biotransform PU and EA into Uro. Uro contributes to strengthening intestinal barrier and reducing inflammatory processes. Yet, Uro production varies greatly among individuals and depend on GM composition. Uro-producing bacteria and precise metabolic pathways need to be further elucidated therefore contributing to personalized and precision nutrition.

Dietary (poly)phenols mitigate inflammatory bowel disease: Therapeutic targets, mechanisms of action, and clinical observations

Inflammatory bowel diseases (IBD), which include Crohn's disease and ulcerative colitis, are a rapidly growing public health concern worldwide. These diseases are heterogeneous at the clinical, immunological, molecular, genetic, and microbial level, but characteristically involve a disrupted immune-microbiome axis. Shortcomings in conventional treatment options warrant the need for novel therapeutic strategies to mitigate these life-long and relapsing disorders of the gastrointestinal tract. Polyphenols, a diverse group of phytochemicals, have gained attention as candidate treatments due to their array of biological effects. Polyphenols exert broad anti-inflammatory and antioxidant effects through the modulation of cellular signaling pathways and transcription factors important in IBD progression. Polyphenols also bidirectionally modulate the gut microbiome, supporting commensals and inhibiting pathogens. One of the primary means by which gut microbiota interface with the host is through the production of metabolites, which are small molecules produced as intermediate or end products of metabolism. There is growing evidence to support that modulation of the gut microbiome by polyphenols restores microbially derived metabolites critical to the maintenance of intestinal homeostasis that are adversely disrupted in IBD. This review aims to define the therapeutic targets of polyphenols that may be important for mitigation of IBD symptoms, as well as to collate evidence for their clinical use from randomized clinical trials.

Urolithin A's Antioxidative, Anti-Inflammatory, and Antiapoptotic Activities Mitigate Doxorubicin-Induced Liver Injury in Wistar Rats

Human colon microbiota produce a metabolite called urolithin A (URO A) from ellagic acid and linked compounds, and this metabolite has been demonstrated to have antioxidant, anti-inflammatory, and antiapoptotic activities. The current work examines the various mechanisms through which URO A protects against doxorubicin (DOX)-induced liver injury in Wistar rats. In this experiment, Wistar rats were administered DOX intraperitoneally (20 mg kg^-1) on day 7 while given URO A intraperitoneally (2.5 or 5 mg kg^-1 d^-1) for 14 days. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma glutamyl transferase (GGT) were measured. Hematoxylin and eosin (HE) staining was used to evaluate histopathological characteristics, and then antioxidant and anti-inflammatory properties were evaluated in tissue and serum, respectively. We also looked at how active caspase 3 and cytochrome c oxidase were in the liver. The findings demonstrated that supplementary URO A therapy clearly mitigated DOX-induced liver damage. The antioxidant enzymes SOD and CAT were elevated in the liver, and the levels of inflammatory cytokines, such as TNF-α, NF-kB, and IL-6, in the tissue were significantly attenuated, all of which complemented the beneficial effects of URO A in DOX-induced liver injury. In addition, URO A was able to alter the expression of caspase 3 and cytochrome c oxidase in the livers of rats that were subjected to DOX stress. These results showed that URO A reduced DOX-induced liver injury by reducing oxidative stress, inflammation, and apoptosis.

Natural compounds regulate the PI3K/Akt/GSK3β pathway in myocardial ischemia-reperfusion injury

The PI3K/Akt/GSK3β pathway is crucial in regulating cardiomyocyte growth and survival. It has been shown that activation of this pathway alleviates the negative impact of ischemia-reperfusion. Glycogen synthase kinase-3 (GSK3β) induces apoptosis through stimulation of transcription factors, and its phosphorylation has been suggested as a new therapeutic target for myocardial ischemia-reperfusion injury (MIRI). GSK3β regulatory role is mediated by the reperfusion injury salvage kinase (RISK) pathway, and its inhibition by Akt activation blocks mitochondrial permeability transition pore (mPTP) opening and enhances myocardial survival. The present article discusses the involvement of the PI3K/Akt/GSK3β pathway in cardioprotective effects of natural products against MIRI.Abbreviations: Akt: protein kinase B; AMPK: AMP-activated protein kinase; ATP: adenosine triphosphate; Bad: bcl2-associated agonist of cell death; Bax: bcl2-associated x protein; Bcl-2: B-cell lymphoma 2; CK-MB: Creatine kinase-MB; CRP: C-reactive-protein; cTnI: cardiac troponin I; EGCG: Epigallocatechin-3-gallate; Enos: endothelial nitric oxide synthase; ER: endoplasmic reticulum; ERK ½: extracellular signal‑regulated protein kinase ½; GSK3β: glycogen synthase kinase-3; GSRd: Ginsenoside Rd; GSH: glutathione; GSSG: glutathione disulfide; HO-1: heme oxygenase-1; HR: hypoxia/reoxygenation; HSYA: Hydroxysafflor Yellow A; ICAM-1: Intercellular Adhesion Molecule 1; IKK-b: IκB kinase; IL: interleukin; IPoC: Ischemic postconditioning; IRI: ischemia-reperfusion injury; JNK: c-Jun N-terminal kinase; Keap1: kelch-like ECH-associated protein- 1; LDH: lactate dehydrogenase; LVEDP: left ventricular end diastolic pressure; LVP: left ventricle pressure; LVSP: left ventricular systolic pressure; MAPK: mitogen-activated protein kinase; MDA: malondialdehyde; MIRI: myocardial ischemia-reperfusion injury; MnSOD: manganese superoxide dismutase; mPTP: mitochondrial permeability transition pore; mtHKII: mitochondria-bound hexokinase II; Nrf-1: nuclear respiratory factor 1; Nrf2: nuclear factor erythroid 2-related factor; NO: nitric oxide; PGC-1α: peroxisome proliferator‑activated receptor γ coactivator‑1α; PI3K: phosphoinositide 3-kinases; RISK: reperfusion injury salvage kinase; ROS: reactive oxygen species; RSV: Resveratrol; SOD: superoxide dismutase; TFAM: transcription factor A mitochondrial; TNF-α: tumor necrosis factor-alpha; VEGF-B: vascular endothelial growth factor B.

Differential Role of Active Compounds in Mitophagy and Related Neurodegenerative Diseases

Neurodegenerative diseases, such as Alzheimer’s disease or Parkinson’s disease, significantly reduce the quality of life of patients and eventually result in complete maladjustment. Disruption of the synapses leads to a deterioration in the communication of nerve cells and decreased plasticity, which is associated with a loss of cognitive functions and neurodegeneration. Maintaining proper synaptic activity depends on the qualitative composition of mitochondria, because synaptic processes require sufficient energy supply and fine calcium regulation. The maintenance of the qualitative composition of mitochondria occurs due to mitophagy. The regulation of mitophagy is usually based on several internal mechanisms, as well as on signals and substances coming from outside the cell. These substances may directly or indirectly enhance or weaken mitophagy. In this review, we have considered the role of some compounds in process of mitophagy and neurodegeneration. Some of them have a beneficial effect on the functions of mitochondria and enhance mitophagy, showing promise as novel drugs for the treatment of neurodegenerative pathologies, while others contribute to a decrease in mitophagy.

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.

Study on the biological mechanism of urolithin a on nasopharyngeal carcinoma in vitro

CONTEXT

Urolithin A (UroA) can inhibit the growth of many human cancer cells, but it has not be reported if UroA inhibits nasopharyngeal carcinoma (NPC) cells.

OBJECTIVE

To explore the inhibitory effect of UroA on NPC and potential mechanism in vitro.

MATERIALS AND METHODS

RNA-sequencing-based mechanistic prediction was conducted by comparing KEGG enrichment of 40 μM UroA-treated for 24 h with untreated CNE2 cells. The untreated cells were selected as control. After NPC cells were treated with 20-60 μM UroA, proliferation, migration and invasion of were measured by colony formation, wound healing and transwell experiments. Apoptosis, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) were measured by flow cytometry, Hoechst 33342, Rhodamine 123, JC-1 staining and ROS assay methods, respectively. Gene and protein expression were measured by RT-qPCR and Western blotting assay.

RESULTS

RNA-sequencing and KEGG enrichment revealed UroA mainly altered the ECM receptor interaction pathway. UroA inhibited cells proliferation, epithelial-mesenchymal-transition pathway, migration and invasion with IC₅₀ values of 34.72 μM and 44.91 μM, induced apoptosis, MMP depolarization and increase ROS content at a concentration of 40 μM. UroA up-regulated E-cadherin, Bax/Bcl-2, c-caspase-3 and PARP proteins, while inhibiting COL4A1, MMP2, MMP9, N-cadherin, Vimentin and Snail proteins at 20-60 μM. Moreover, co-treatment of UroA (40 μM) and NAC (5 mM) could reverse the effect of UroA on apoptosis-related proteins.

DISCUSSION AND CONCLUSIONS

RNA-sequencing technology based on bioinformatic analyses may be applicable for studiying the mechanism of drugs for tumour treatment.

Natural polyphenols: a potential prevention and treatment strategy for metabolic syndrome

Metabolic syndrome (MS) is the term for a combination of hypertension, dyslipidemia, insulin resistance, and central obesity as factors leading to cardiovascular and metabolic disease. Epidemiological investigation has shown that polyphenol intake is negatively correlated with the incidence of MS. Natural polyphenols are widely found in cocoa beans, tea, vegetables, fruits, and some Chinese herbal medicines; they are a class of plant compounds containing a variety of phenolic structural units, which are potent antioxidants and anti-inflammatory agents in plants. Polyphenols are composed of flavonoids (such as flavanols, anthocyanidins, anthocyanins, isoflavones, etc.) and non-flavonoids (such as phenolic acids, stilbenes, and lignans). Modern pharmacological studies have proved that polyphenols can reduce blood pressure, improve lipid metabolism, lower blood glucose, and reduce body weight, thereby preventing and improving MS. Due to the unique characteristics and potential development and application value of polyphenols, this review summarizes some natural polyphenols that could treat MS, including their chemical properties, plant sources, and pharmacological action against MS, to provide a basis for the further study of polyphenols in MS.

Current Knowledge on Interactions of Plant Materials Traditionally Used in Skin Diseases in Poland and Ukraine with Human Skin Microbiota

Skin disorders of different etiology, such as dermatitis, atopic dermatitis, eczema, psoriasis, wounds, burns, and others, are widely spread in the population. In severe cases, they require the topical application of drugs, such as antibiotics, steroids, and calcineurin inhibitors. With milder symptoms, which do not require acute pharmacological interventions, medications, dietary supplements, and cosmetic products of plant material origin are gaining greater popularity among professionals and patients. They are applied in various pharmaceutical forms, such as raw infusions, tinctures, creams, and ointments. Although plant-based formulations have been used by humankind since ancient times, it is often unclear what the mechanisms of the observed beneficial effects are. Recent advances in the contribution of the skin microbiota in maintaining skin homeostasis can shed new light on understanding the activity of topically applied plant-based products. Although the influence of various plants on skin-related ailments are well documented in vivo and in vitro, little is known about the interaction with the network of the skin microbial ecosystem. The review aims to summarize the hitherto scientific data on plant-based topical preparations used in Poland and Ukraine and indicate future directions of the studies respecting recent developments in understanding the etiology of skin diseases. The current knowledge on investigations of interactions of plant materials/extracts with skin microbiome was reviewed for the first time.

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.

Tiliae flos metabolites and their beneficial influence on human gut microbiota biodiversity ex vivo

ETHNOPHARMACOLOGICAL RELEVANCE

The linden flower (Tiliae flos) has been used for centuries to treat and relieve symptoms of the common cold, throat irritation, and upper respiratory tract disturbances. Traditionally, this herb is administered orally, and thus it undergoes intestinal metabolism. Although it is pharmacopeial plant material, there are no reports about its interaction with human gut microbiota.

AIM OF THE STUDY

The study aimed to determine the interaction between human gut microbiota and the linden flower extracts, resulting in the biotransformation of the extract's constituents and changes in the microbiota composition.

MATERIAL AND METHODS

The linden flower metabolites were obtained by incubation of extract with human faecal slurries from 5 healthy donors. The UHPLC-DAD-MSⁿ analysis determined the composition of raw extract and analysis of microbial metabolites. The intestinal microbiota isolation and sequencing were used to determine changes in microbiota composition. The anti-inflammatory activity was tested using the LPS-stimulated human neutrophils model and ELISA test.

RESULTS

After incubation of linden flower extract with human gut microbiota, twenty metabolites were detected and characterized, and three among them were identified. The extract changed human gut microbiota composition but did not cause dysbiosis (change in the abundance of forty-three genera). Raw extract and their metabolites exhibit different levels of inhibition of cytokines production by LPS-stimulated neutrophils, but the reduction of TNF-α production was observed.

CONCLUSIONS

The linden flower extract has a beneficial influence on human gut microbiota because it promotes increasing the abundance of bacteria responsible for SCFAs production. The anti-inflammatory effect might be linked to both microbiota composition changes and direct activity of bioavailable metabolites. Increased abundance of SCFAs producers may inhibit the production of pro-inflammatory cytokines. A low concentration of phenolic compounds in metabolized linden flower extract and responsible for anti-inflammatory properties, and the multitude of biological and chemical particles and their interactions may weaken these properties.

Potential of Establishing the Corresponding Human Microbial Community in Pseudo Germ-Free Mice through Fecal Microbe Transfer from Three Urolithin Metabotypes

Three urolithin metabotypes (UMs) have been defined in the population according to final urolithins converted by gut microbiota. Currently, it is difficult to establish the cause-and-effect relationship between urolithins and microbiota in human studies. Studies on the health effects of ellagic acid (EA) in animal models rarely consider the differences in the urolithin production. Therefore, the objective of this study is to establish human microbiota-associated (HMA) mice, imitating the microbiota composition of the three UMs. Antibiotic-induced pseudo germ-free mice were gavaged with fecal bacteria of the three UM donors for four weeks. The results showed that the ability to produce corresponding urolithins was successfully transferred from the donor of the three UMs to HMA mice. The three UM HMA mice adopted a humanized microbiota profile similar to their corresponding donor. The family Eggerthellaceae and genera Eggerthella and Gordonibacter were successfully transferred and colonized from UM-A/B donors to HMA mice. Overall, the three UM HMA mouse models were successfully established, which provide a basis for exploring the health effects of EA.

Modulation of gut microbiota by bioactive compounds for prevention and management of type 2 diabetes

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by hyperglycemia and insulin resistance. Gut microbiota (GM) are specific groups of microbes colonized in the gastrointestinal (GI) tract. They profoundly influence health, disease protection, and associated with metabolic activities, and play a vital role in the production of functional metabolites from dietary substances. Dysbiosis of GM has been linked to the onset of T2DM and can be altered to attain eubiosis by intervention with various nutritional bioactive compounds such as polyphenols, prebiotics, and probiotics. This review presents an overview of the evidence and underlying mechanisms by which bioactive compounds modulate the GM for the prevention and management of T2DM.

Conjugates of urolithin A with NSAIDs, their stability, cytotoxicity, and anti-inflammatory potential

Urolithin A (UA, 1), a gut microbiota postbiotic metabolite is attributed to express interesting biological activities indicated by in vitro, in vivo and clinical studies. Due to its strong anti-inflammatory properties it is considered as a promising lead molecule for further drug development, however, its strong phase II metabolism, severely limits its oral application. Therefore, monoesterified UA derivatives with selected NSAIDs: ibuprofen (Mix 3a/3b), mefenamic acid (Mix 4a/4b), diclofenac (Mix 5a/5b) and aspirin (Mix 6a/6b) were designed. Performed array of stability assays indicated Mix 4a/4b as a most suitable candidate for further studies due to its exceptional stability in human plasma. Thus, we evaluated effects of Mix 4a/4b on cell viability as well as the impact on cytokines secretion in THP-1 derived macrophages and compared it to UA. At high concentration (50 µM) Mix 4a/4b expressed a cytotoxic effect, however at concentration of 5 µM it significantly suppressed TNF-α secretion, and significantly increased ani-inflammatory IL-10 secretion at 10 µM without affecting cell viability. This work has led to selection of a novel UA derivatives, which are stable in solutions and in human plasma as well as posess anti-inflammatory activity towards THP-1 macrophages at non-cytotoxic concentrations.

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.

Antioxidant, Anti-Inflammatory and Cytotoxic Activity of Phenolic Compound Family Extracted from Raspberries (Rubus idaeus): A General Review

Raspberries (Rubus idaeus) possess a wide phenolic family profile; this serves the role of self-protection for the plant. Interest in these compounds have significantly increased, since they have been classified as nutraceuticals due to the positive health effects provided to consumers. Extensive chemical, in vitro and in vivo studies have been performed to prove and validate these benefits and their possible applications as an aid when treating several chronic degenerative diseases, characterized by oxidative stress and an inflammatory response. While many diseases could be co-adjuvanted by the intake of these phenolic compounds, this review will mainly discuss their effects on cancer. Anthocyanins and ellagitannins are known to provide a major antioxidant capacity in raspberries. The aim of this review is to summarize the current knowledge concerning the phenolic compound family of raspberries, and topics discussed include their characterization, biosynthesis, bioavailability, cytotoxicity, antioxidant and anti-inflammatory activities.

Urolithin B suppressed osteoclast activation and reduced bone loss of osteoporosis via inhibiting ERK/NF-κB pathway

Objectives

The main target of current drugs for alleviating bone loss is osteoclasts. However, the long‐term application of such drugs will also cause side effects. Therefore, it is of great need to develop new and safer therapeutics for osteoporosis. In recent years, drug development based on gut microbiota has gradually attracted attention. This manuscript investigates the inhibitory effect of urolithin B (UB) on osteoclastogenesis and differentiation in vitro and in ovariectomized (OVX) mice.

Materials and Methods

CCK‐8 was used to analyse the cytotoxicity of UB; BMMs cells were differentiated into osteoclasts by RANKL, and respectively treated with 1, 5, and 25 μmol/L UB during this process. After one week of intervention, tartrate‐resistant acid phosphatase (TRAP) staining was used to analyse the number and average area of osteoclasts. F‐actin staining and immunofluorescence staining were conducted to evaluate the morphology and function of osteoclasts. Bone resorption function of osteoclasts was detected by Pit Formation Assay. The expression of osteoclast‐related protein genes in RAW264.7 cells were investigated via western blot and RT‐PCR assays. Western blot analysis of RANKL‐mediated activation of MAPK/NF‐κB pathway after 0, 5, 15, 30, 60 min of intervention. For in vivo experiments, OVX mice received intraperitoneal injection of 10, 50 mg/kg every two days, 8 weeks later, the femurs of mice were taken for morphological analysis, and the serum content of CTX‐1, a bone metabolism index, was analysed.

Results

UB could inhibit the osteoclast differentiation of rankl‐induced bone marrow macrophages (BMMs) and RAW264.7 cells in vitro, suppress the uptake activity of hydroxyapatite and expression of osteoclast‐related gene MMP9, CTSK, NFATc1 and c‐fos. Furthermore, UB repressed the rankl‐induced phosphorylation and degradation of IκB and the phosphorylation of P65 in the NF‐κB pathway of RAW264.7 cells, and also down‐regulated the phosphorylation level of ERK in the MAPK pathway. For in vivo studies, UB‐treated OVX mice showed more significant improved various parameters of distal femur compared with the control group, with fewer NFATc1, MMP9 and TRAP‐positive osteoclasts in bone tissues, and less serum content of CTX‐1.

Conclusion

Urolithin B attenuated bone loss in OVX mice by inhibiting the formation and activation of osteoclasts via down‐regulation of the ERK/NF‐κB signalling pathway.

Roles of miR-124-3p/Scd1 in urolithin A-induced brown adipocyte differentiation and succinate-dependent regulation of mitochondrial complex II

Brown adipocytes have been linked to managing human obesity and related metabolic diseases. A large number of natural products have emerged that can activate brown adipocytes tissue (BAT) to active thermogenesis, but the epigenetic mechanisms have not been fully resolved. In this study, we identified the induction of miR-124-3p by urolithin A (UA) as a means to increase the thermogenic activity of brown adipocytes. Overexpression of miR-124-3p enhances thermogenesis by increasing mitochondrial content in brown adipocytes. Mechanistically, to clarify that miR-124-3p affects fatty acid synthesis using bioinformatics methods, it is clear that miR-124 affects the synthesis of fatty acids through the enrichment analysis of the KEGG pathway, and using dual luci. ferase to determine the target gene as stearoyl-CoA desaturase 1 (SCD1) while controlling rates of fatty acids synthesis and de novo brown fat biogenesis. Finally, in the overexpression of miR-124-3p and UA-treated BAT, succinate accumulation was enhanced in cells and fueled mitochondrial complex II activities. This study highlights a miR-124-3p/SCD1/succinate pathway that stimulates thermogenesis of BAT via the modulatory roles of UA.

Are mitophagy enhancers therapeutic targets for Alzheimer's disease?

Healthy mitochondria are essential for functional bioenergetics, calcium signaling, and balanced redox homeostasis. Dysfunctional mitochondria are a central aspect of aging and neurodegenerative diseases such as Alzheimer's disease (AD). The formation and accumulation of amyloid beta (Aβ) and hyperphosphorylated tau (P-tau) play large roles in the cellular changes seen in AD, including mitochondrial dysfunction, synaptic damage, neuronal loss, and defective mitophagy. Mitophagy is the cellular process whereby damaged mitochondria are selectively removed, and it plays an important role in mitochondrial quality control. Dysfunctional mitochondria are associated with increased reactive oxygen species and increased levels of Aβ, P-tau and Drp1, which together trigger mitophagy and autophagy. Impaired mitophagy causes the progressive accumulation of defective organelles and damaged mitochondria, and it has been hypothesized that the restoration of mitophagy may offer therapeutic benefits to AD patients. This review highlights the challenges of pharmacologically inducing mitophagy through two different signaling cascades: 1) The PINK1/parkin-dependent pathway and 2) the PINK1/parkin-independent pathway, with an emphasis on abnormal mitochondrial interactions with Aβ and P-Tau, which alter mitophagy in an age-dependent manner. This article also summarizes recent studies on the effects of mitophagy enhancers, including urolithin A, NAD+, actinonin, and tomatidine, on mutant APP/Aβ and mutant Tau. Findings from our lab have revealed that mitophagy enhancers can suppress APP/Aβ-induced and mutant Tau-induced mitochondrial and synaptic dysfunctions in mouse and cell line models of AD. Finally, we discuss the mechanisms underlying the beneficial health effects of mitophagy enhancers like urolithin A, NAD+, resveratrol and spermidine in AD.

Distribution of Urolithins Metabotypes in Healthy Chinese Youth: Difference in Gut Microbiota and Predicted Metabolic Pathways

This is the first study to report the distribution of urolithin metabotypes (UMs) in Asian people, specifically in the Chinese. As was reported for Europeans and Latin Americans, three UMs were observed, UM-A (54.3%), UM-B (31.4%), and UM-0 (14.3%), in 35 healthy Chinese youth. The richness and diversity of gut microbiota were lower in UM-0 than in UM-A and UM-B at the genus level. Gordonibacter in UM-A and UM-B was significantly higher than that in UM-0. The Akkermansia was not found in UM-0. The correlation analysis between the type and content of urolithins and the gut microbiota at the genus level showed that 27 genera were significantly positively correlated with urolithin A and 20 genera were significantly positively associated with isourolithin A and urolithin B. In addition, different KEGG pathways such as TCA cycle, energy metabolism, and some disease were found between the gut microbiome of the three UMs. Further research is needed to explore the mechanisms of metabotypes and the differential health benefits or illness predisposition of the three UMs.

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.

Potential Modulatory Microbiome Therapies for Prevention or Treatment of Inflammatory Bowel Diseases

A disturbed interaction between the gut microbiota and the mucosal immune system plays a pivotal role in the development of inflammatory bowel disease (IBD). Various compounds that are produced by the gut microbiota, from its metabolism of diverse dietary sources, have been found to possess anti-inflammatory and anti-oxidative properties in in vitro and in vivo models relevant to IBD. These gut microbiota-derived metabolites may have similar, or more potent gut homeostasis-promoting effects compared to the widely-studied short-chain fatty acids (SCFAs). Available data suggest that mainly members of the Firmicutes are responsible for producing metabolites with the aforementioned effects, a phylum that is generally underrepresented in the microbiota of IBD patients. Further efforts aiming at characterizing such metabolites and examining their properties may help to develop novel modulatory microbiome therapies to treat or prevent IBD.

Synergic interactions between polyphenols and gut microbiota in mitigating inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are a group of chronic and recurring inflammatory conditions in the colon and intestine. Their etiology is not fully understood but involves the combination of gut dysbiosis, genetics, immune functions, and environmental factors including diet. Polyphenols from plant-based food synergistically interact with gut microbiota to suppress inflammation and alleviate symptoms of IBD. Polyphenols increase the diversity of gut microbiota, improve the relative abundance of beneficial bacteria, and inhibit the pathogenic species. Polyphenols not absorbed in the small intestine are catabolized in the colon by microbiota into microbial metabolites, many of which have higher anti-inflammatory activity and bioavailability than their precursors. The polyphenols and their microbial metabolites alleviate IBD through reduction of oxidative stress, inhibition of inflammatory cytokines secretion (TNF-α, IL-6, IL-8, and IL-1β), suppression of NF-κB, upregulation of Nrf2, gut barrier protection, and modulation of immune function. Future studies are needed to discover unknown microbial metabolites of polyphenols and correlate specific gut microbes with microbial metabolites and IBD mitigating activity. A better knowledge of the synergistic interactions between polyphenols and gut microbiota will help to devise more effective prevention strategies for IBD. This review focuses on the role of polyphenols, gut microbiota and their synergistic interactions on the alleviation of IBD as well as current trends and future directions of IBD management.

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.

Immunomodulatory Role of Urolithin A on Metabolic Diseases

Urolithin A (UroA) is a gut metabolite produced from ellagic acid-containing foods such as pomegranates, berries, and walnuts. UroA is of growing interest due to its therapeutic potential for various metabolic diseases based on immunomodulatory properties. Recent advances in UroA research suggest that UroA administration attenuates inflammation in various tissues, including the brain, adipose, heart, and liver tissues, leading to the potential delay or prevention of the onset of Alzheimer’s disease, type 2 diabetes mellitus, and non-alcoholic fatty liver disease. In this review, we focus on recent updates of the anti-inflammatory function of UroA and summarize the potential mechanisms by which UroA may help attenuate the onset of diseases in a tissue-specific manner. Therefore, this review aims to shed new insights into UroA as a potent anti-inflammatory molecule to prevent immunometabolic diseases, either by dietary intervention with ellagic acid-rich food or by UroA administration as a new pharmaceutical drug.

High molecular pyrogens present in plant extracts interfere with examinations of their immunomodulatory properties in vitro

The widely accepted strategy to justify the use of medicinal plant extracts in diseases with inflammatory background is their examination on in vitro models using immune cells. It is also a key initial step of research for active principles, which could be then isolated and tested on more advanced models, becoming new pharmacologically active lead molecules. The crucial aspect which has not been so far addressed in this context, is the presence of pyrogens in plant preparations. The aim of this study was the examination of pyrogens interference with in vitro evaluation of anti-inflammatory activity of plant extracts using human primary neutrophils model together with introduction of effective method of interfering factors elimination. The obtained results showed that chosen plant extracts contained pyrogens, which were responsible for concentration-dependent stimulation of pro-inflammatory cytokines production by human neutrophils in vitro in the same extent as LPS did. The ultrafiltration method was successfully applied for pyrogens elimination, which effectiveness was confirmed using LAL test. The determined interference of pyrogens implies the necessity of their consideration and removal when in vitro studies include direct addition of plant extracts to the cell culture, what can be obtained by ultrafiltration, which does not affect extract composition.

Preclinical Evaluation of Oral Urolithin-A for the Treatment of Acute Campylobacteriosis in Campylobacter jejuni Infected Microbiota-Depleted IL-10-/- Mice

Human campylobacteriosis represents an infectious enteritis syndrome caused by Campylobacter species, mostly Campylobacter jejuni. Given that C. jejuni infections are rising worldwide and antibiotic treatment is usually not indicated, novel treatment options for campylobacteriosis are needed. Urolithin-A constitutes a metabolite produced by the human gut microbiota from ellagitannins and ellagic acids in berries and nuts which have been known for their health-beneficial including anti-inflammatory effects since centuries. Therefore, we investigated potential pathogen-lowering and immunomodulatory effects following oral application of synthetic urolithin-A during acute campylobacteriosis applying perorally C. jejuni infected, microbiota-depleted IL-10^-/- mice as preclinical inflammation model. On day 6 post infection, urolithin-A treated mice harbored slightly lower pathogen loads in their ileum, but not colon as compared to placebo counterparts. Importantly, urolithin-A treatment resulted in an improved clinical outcome and less pronounced macroscopic and microscopic inflammatory sequelae of infection that were paralleled by less pronounced intestinal pro-inflammatory immune responses which could even be observed systemically. In conclusion, this preclinical murine intervention study provides first evidence that oral urolithin-A application is a promising treatment option for acute C. jejuni infection and paves the way for future clinical studies in human campylobacteriosis.

Implication of the Gut Microbiota in Metabolic Inflammation Associated with Nutritional Disorders and Obesity

SCOPE

More than a decade ago, the concept of "metabolic endotoxemia" is elaborated on the fact that some bacterial components, classified as microbial associated membrane pathogens (MAMPs) can pass through the gut barrier and create a systemic low tone inflammation.

METHODS AND RESULTS

The translocation of lipopolysaccharides and its contribution to systemic inflammation are largely studied in murine models of obesity, allowing to unravel the molecular pathways involved in the process. Many different pathological contexts evoke the loss of gut barrier as an event contributing to inflammation and thereby driving metabolic and behavioral alterations.

CONCLUSION

This review describes the role of nutrition as a modulator of metabolic regulation and focuses on the contribution of the gut microbiota in the process of the production of a large diversity of bioactive metabolites. The two first sections of the review will be dedicated to the impact of nutritional disorders on both the gut microbiota composition and on metabolic inflammation. The last and more prominent section will describe the role of different nutrient-derived gut metabolites on the gut barrier integrity, metabolic inflammation, and peripheral tissue alterations during obesity or associated complications.

Antihyperuricemic Effect of Urolithin A in Cultured Hepatocytes and Model Mice

Hyperuricemia is defined as a disease with high uric acid (UA) levels in the blood and a strong risk factor for gout. Urolithin A (UroA) is a main microbial metabolite derived from ellagic acid (EA), which occurs in strawberries and pomegranates. In this study, we evaluated antihyperuricemic effect of UroA in both cultured hepatocytes and hyperuricemic model mice. In cultured hepatocytes, UroA significantly and dose-dependently reduced UA production. In model mice with purine bodies-induced hyperuricemia, oral administration of UroA significantly inhibited the increase in plasma UA levels and hepatic xanthine oxidase (XO) activity. In addition, DNA microarray results exhibited that UroA, as well as allopurinol, a strong XO inhibitor, induced downregulation of the expression of genes associated with hepatic purine metabolism. Thus, hypouricemic effect of UroA could be, at least partly, attributed to inhibition of purine metabolism and UA production by suppressing XO activity in the liver. These results indicate UroA possesses a potent antihyperuricemic effect and it could be a potential candidate for a molecule capable of preventing and improving hyperuricemia and gout.

Data-driven microbiota biomarker discovery for personalized drug therapy of cardiovascular disease

Cardiovascular disease (CVD) is the most wide-spread disorder all over the world. The personalized and precision diagnosis, treatment and prevention of CVD is still a challenge. With the developing of metagenome sequencing technologies and the paradigm shifting to data-driven discovery in life science, the computer aided microbiota biomarker discovery for CVD is becoming reality. We here summarize the data resources, knowledgebases and computational models available for CVD microbiota biomarker discovery, and review the present status of the findings about the microbiota patterns associated with the therapeutic effects on CVD. The future challenges and opportunities of the translational informatics on the personalized drug usages in CVD diagnosis, prognosis and treatment are also discussed.

Comparative studies of urolithins and their phase II metabolites on macrophage and neutrophil functions

Purpose

Ellagitannins are high molecular weight polyphenols present in high quantities in various food products. They are metabolized by human and animal gut microbiota to postbiotic metabolites-urolithins, bioavailable molecules of a low molecular weight. Following absorption in the gut, urolithins rapidly undergo phase II metabolism. Thus, to fully evaluate the mechanisms of their biological activity, the in vitro studies should be conducted for their phase II conjugates, mainly glucuronides. The aim of the study was to comparatively determine the influence of urolithin A, iso-urolithin A, and urolithin B together with their respective glucuronides on processes associated with the inflammatory response.

Methods

The urolithins obtained by chemical synthesis or isolation from microbiota cultures were tested with their respective glucuronides isolated from human urine towards modulation of inflammatory response in THP-1-derived macrophages, RAW 264.7 macrophages, PBMCs-derived macrophages, and primary neutrophils.

Results

Urolithin A was confirmed to be the most active metabolite in terms of LPS-induced inflammatory response inhibition (TNF-α attenuation, IL-10 induction). The observed strong induction of ERK1/2 phosphorylation has been postulated as the mechanism of its action. None of the tested glucuronide conjugates was active in terms of pro-inflammatory TNF-α inhibition and anti-inflammatory IL-10 and TGF-β1 induction.

Conclusion

Comparative studies of the most abundant urolithins and their phase II conjugates conducted on human and murine immune cells unambiguously confirmed urolithin A to be the most active metabolite in terms of inhibition of the inflammatory response. Phase II metabolism was shown to result in the loss of urolithins’ pharmacological properties.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02386-y) contains supplementary material, which is available to authorized users.

Protective Effects of Polyphenols Present in Mediterranean Diet on Endothelial Dysfunction

Endothelial dysfunction tends to be the initial indicator in proinflammatory state and macro- and microvascular complications, such as atherosclerosis and cardiovascular diseases. It has been shown that certain compounds in diet can generate beneficial effects on cardiovascular disease due to its interactions with endothelial cells. Thus, this review is aimed at investigating whether certain polyphenols present in the Mediterranean diet, specifically catechin, quercetin, resveratrol, and urolithin, could exert positive effects on endothelial dysfunction. After analysis of numerous papers, we found that polyphenols aiding endothelial function is beneficial not only for patients with cardiovascular disease, diabetes, or endothelial dysfunction but for all people as it can improve the effects of aging on the endothelia. The additional benefit of these polyphenols on weight loss further improves health and lowers the risk of several diseases, including those caused by endothelial dysfunction. However, it is important to note that the dosages in the majorities of the studies mentioned in this review were of supplemental rather than nutritionally relevant quantities, and therefore, the recommended dosages are difficult to determine.

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.

Bioactive compounds with anti-oxidative and anti-inflammatory activities of hop extracts

The aim of this study is to simultaneously evaluate anti-oxidative and anti-inflammatory activities of the hop extracts by different solvents. Hop water extract (HWE) and hop ethanol extracts (HEEs) were prepared by extracting hop pellets with hot water at 90 °C and ethanol solutions (55%, 75%, and 95%), respectively. Bioactive compound such as α-acid, β-acid, total phenolic, and total flavonoid contents were determined. All the HEEs showed higher anti-oxidative activities than the HWEs. The HEEs showing the highest anti-oxidative activities are different in the experiments with different free radicals. For anti-inflammatory activities, both the HWE and HEEs decreased NO productions. HWE decreased TNF-α and IL-6 secretion but showed no effect on IL-1β, while HEEs decreased IL-1β and IL-6 secretion but increased TNF-α secretion. Except for TNF-α secretion, the HEEs showed higher anti-inflammatory activities than the HWE. Future work is to explore the possible mechanism to improve the ethanol extraction procedure.

Urolithin A attenuated ox-LDL-induced cholesterol accumulation in macrophages partly through regulating miR-33a and ERK/AMPK/SREBP1 signaling pathways

Promoting cholesterol efflux from foam cells represents one of the therapeutic strategies for ameliorating atherosclerosis. Urolithin A (UA) has been shown before to attenuate ox-LDL induced endothelial dysfunction in endothelial cells with its anti-inflammatory properties. The aim of this study was to investigate whether UA could promote cholesterol efflux via modulating related microRNA (miR) and signaling pathways. RAW264.7 cells were treated with 50 μg mL^-1 ox-LDL to induce foam cell formation. After treatment with UA at different concentrations, intercellular and extracellular cholesterol levels were determined. Expression of Erk1/2, AMPKα and their phosphorylation forms, and SREBP1, was analyzed by western-blotting. The effect of UA on miR-33a expression and the involvement of miR-33a in cholesterol efflux regulation were also investigated. UA reduced ox-LDL induced cholesterol accumulation in macrophage cells and promoted cholesterol efflux from cells. Compared with ox-LDL treated cells, UA treatment reduced the level of phosphorylated ERK1/2, increased the expression of phosphorylated AMPKα and decreased the SREBP1 expression. Moreover, UA decreased the miR-33a expression at the transcriptional level but increased the transcriptional expression of ATP-binding cassette transporter A1 (ABCA1) and ABCG1, two genes contributing to reverse cholesterol transport. Furthermore, pre-miR-33a attenuated cholesterol efflux induced by UA. Collectively, UA promoted the reverse cholesterol transport in macrophage-derived foam cells and interfered with cholesterol metabolism possibly through regulating the miRNA-33 expression and interaction with the ERK/AMPKα/SREBP1 signaling pathway.