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14 pages, 2501 KiB  
Article
Urolithin A Modulates PER2 Degradation via SIRT1 and Enhances the Amplitude of Circadian Clocks in Human Senescent Cells
by Rassul Kuatov, Jiro Takano, Hideyuki Arie, Masaru Kominami, Norifumi Tateishi, Ken-ichi Wakabayashi, Daisuke Takemoto, Takayuki Izumo, Yoshihiro Nakao, Wataru Nakamura, Kazuyuki Shinohara and Yasukazu Nakahata
Nutrients 2025, 17(1), 20; https://doi.org/10.3390/nu17010020 - 25 Dec 2024
Viewed by 479
Abstract
Background/Objectives: Circadian clocks are endogenous systems that regulate numerous biological, physiological, and behavioral events in living organisms. Aging attenuates the precision and robustness of circadian clocks, leading to prolonged and dampened circadian gene oscillation rhythms and amplitudes. This study investigated the effects of [...] Read more.
Background/Objectives: Circadian clocks are endogenous systems that regulate numerous biological, physiological, and behavioral events in living organisms. Aging attenuates the precision and robustness of circadian clocks, leading to prolonged and dampened circadian gene oscillation rhythms and amplitudes. This study investigated the effects of food-derived polyphenols such as ellagic acid and its metabolites (urolithin A, B, and C) on the aging clock at the cellular level using senescent human fibroblast cells, TIG-3 cells. Methods: Lentivirus-infected TIG-3 cells expressing Bmal1-luciferase were used for real-time luciferase monitoring assays. Results: We revealed that urolithins boosted the amplitude of circadian gene oscillations at different potentials; urolithin A (UA) amplified the best. Furthermore, we discovered that UA unstabilizes PER2 protein while stabilizing SIRT1 protein, which provably enhances BMAL1 oscillation. Conclusions: The findings suggest that urolithins, particularly UA, have the potential to modulate the aging clock and may serve as therapeutic nutraceuticals for age-related disorders associated with circadian dysfunction. Full article
(This article belongs to the Section Nutrition and Public Health)
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<p>Effects of ellagic acid and urolithin A on the circadian clock of senescent cells. (<b>A</b>) Representative circadian oscillation patterns of DMSO-, ellagic acid (EA; 33.1 μM)-, or urolithin A (UA; 13.1 μM)-treated luciferase driven by <span class="html-italic">Bmal1</span> promoter were shown. (<b>B</b>,<b>C</b>) The period lengths and relative amplitudes were analyzed by the cosinor method using the data from (<b>A</b>). Each sample number was 6 or 7. The value of DMSO was set to 1 for the relative amplitude. ANOVA followed by Dunnett’s post-hoc test was analyzed. Statistical significance compared with the control “DMSO” is indicated as * <span class="html-italic">p</span> &lt; 0.05, or ** <span class="html-italic">p</span> &lt; 0.005.</p>
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<p>Effects of ellagic acid and urolithin A on the circadian clock of proliferative cells. (<b>A</b>) Representative circadian oscillation patterns of DMSO-, EA (33.1 μM)-, or UA (30 μM)-treated luciferase driven by <span class="html-italic">Bmal1</span> promoter were shown. (<b>B</b>,<b>C</b>) The period lengths and relative amplitudes were analyzed by the cosinor method using the data from (<b>A</b>). Each sample number was 5 or 6. The value of DMSO was set to 1 for the relative amplitude. ANOVA followed by Dunnett’s post-hoc test was analyzed. Statistical significance compared with the control “DMSO” is indicated as *** <span class="html-italic">p</span> &lt; 0.001.</p>
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<p>Effects of EA and its derivatives on the circadian clock of senescent cells. (<b>A</b>) Ellagic acid and its metabolites are shown. (<b>B</b>) Representative circadian oscillation patterns of EA-, UA-, UB, or UC-treated luciferase driven by <span class="html-italic">Bmal1</span> promoter were shown. (<b>C</b>) Amplitudes were analyzed with the cosinor method using the data from (<b>B</b>), and the amplitude of 0 mM for each metabolite was set to 1. Each sample number was 5 to 8. Values are presented as the mean ± SEM. ANOVA followed by Dunnett’s post-hoc test was analyzed. Statistical significance compared with the control “0” is indicated as * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, or *** <span class="html-italic">p</span> &lt; 0.001.</p>
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<p>Effects of UA on the circadian clock gene expressions in senescent cells. Circadian gene expression levels after the UA treatment were quantified by qPCR. Each sample was normalized by the amount of <span class="html-italic">18S rRNA</span>. Each gene expression level in DMSO was set to 1. Each sample number was 5 to 9. Values are presented as the mean ± SEM. The Student’s two-tailed <span class="html-italic">t</span>-tests were performed. Statistical significance compared with the control “DMSO” is indicated as * <span class="html-italic">p</span> &lt; 0.05.</p>
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<p>Effects of UA on Per2 protein stability in senescent cells. (<b>A</b>) The protein stability of luciferase-fused Per2 protein (Per2-luc) or luciferase alone (luc) was measured using the real-time monitoring system. (<b>B</b>) Effects of UA on protein stability were analyzed. Values indicate the percentages of t<sub>1/2</sub> of the UA-treated condition divided by t<sub>1/2</sub> of the DMSO-treated condition. Each sample number was 4. Values are presented as the mean ± SEM. The Student’s two-tailed <span class="html-italic">t</span>-tests were performed. Statistical significance compared with the control “luc” is indicated as ** <span class="html-italic">p</span> &lt; 0.01.</p>
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<p>Effects of UA on Sirt1 amount in senescent cells. (<b>A</b>) <span class="html-italic">SIRT1</span> expression levels after the UA treatment were quantified by qPCR. Samples were normalized by the amount of <span class="html-italic">18S rRNA</span>. <span class="html-italic">SIRT1</span> expression level in DMSO was set to 1. The sample numbers were 9. Values are presented as the mean ± SEM. The Student’s two-tailed <span class="html-italic">t</span>-tests were performed. Statistical significance compared with the control “DMSO” is indicated as ** <span class="html-italic">p</span> &lt; 0.01. (<b>B</b>) SIRT1 (upper panel) and a-TUBLIN (bottom panel) protein levels under indicated conditions were detected. The arrowhead indicates non-specific bands.</p>
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<p>Scheme of how UA amplifies circadian gene expression in senescent cells. UA treatment increases the SIRT1 protein amount, which may promote its deacetylation activity and subsequent degradation of PER2, thereby releasing CLOCK/BMAL1 repression by PER/CRY. This enhances oscillatory <span class="html-italic">REV-ERB</span> and thereby <span class="html-italic">BMAL1</span> gene expression.</p>
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19 pages, 1618 KiB  
Review
Polyphenol-Derived Microbiota Metabolites and Cardiovascular Health: A Concise Review of Human Studies
by Ana Clara da C. Pinaffi-Langley, Stefano Tarantini, Norman G. Hord and Andriy Yabluchanskiy
Antioxidants 2024, 13(12), 1552; https://doi.org/10.3390/antiox13121552 - 18 Dec 2024
Viewed by 574
Abstract
Polyphenols, plant-derived secondary metabolites, play crucial roles in plant stress responses, growth regulation, and environmental interactions. In humans, polyphenols are associated with various health benefits, particularly in cardiometabolic health. Despite growing evidence of polyphenols’ health-promoting effects, their mechanisms remain poorly understood due to [...] Read more.
Polyphenols, plant-derived secondary metabolites, play crucial roles in plant stress responses, growth regulation, and environmental interactions. In humans, polyphenols are associated with various health benefits, particularly in cardiometabolic health. Despite growing evidence of polyphenols’ health-promoting effects, their mechanisms remain poorly understood due to high interindividual variability in bioavailability and metabolism. Recent research highlights the bidirectional relationship between dietary polyphenols and the gut microbiota, which can influence polyphenol metabolism and, conversely, be modulated by polyphenol intake. In this concise review, we summarized recent advances in this area, with a special focus on isoflavones and ellagitannins and their corresponding metabotypes, and their effect on cardiovascular health. Human observational studies published in the past 10 years provide evidence for a consistent association of isoflavones and ellagitannins and their metabotypes with better cardiovascular risk factors. However, interventional studies with dietary polyphenols or isolated microbial metabolites indicate that the polyphenol–gut microbiota interrelationship is complex and not yet fully elucidated. Finally, we highlighted various pending research questions that will help identify effective targets for intervention with precision nutrition, thus maximizing individual responses to dietary and lifestyle interventions and improving human health. Full article
(This article belongs to the Special Issue Phenolic Antioxidants)
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<p>Simplified route of digestion, absorption, metabolism, and excretion of dietary polyphenols. Intact polyphenols are poorly absorbed in the gastrointestinal tract. Small aglycones are absorbed in the small intestine and undergo phase I and II liver metabolism before reaching the bloodstream and target tissues. Complex polyphenols accumulate in the colon, where they undergo extensive catabolism by the gut microbiota. Microbial metabolites can then be absorbed and undergo further biotransformation before reaching circulation and target tissues. Created with BioRender.com.</p>
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<p>Pomegranates, walnuts, and berries like strawberries and raspberries are dietary sources of parent polyphenolic compounds ellagitannins, such as (1) β-punicalagins, and (2) ellagic acid. Upon ingestion, these polyphenolic compounds are poorly bioavailable and accumulate in the lower gastrointestinal tract. Bacterial species in the colon are involved in the catabolism of ellagitannins and ellagic acids. Main catabolic reactions are ester hydrolysis to release ellagic acid from ellagitannins, cleavage of the carbon–oxygen bond to open a lactone ring, and sequential de-hydroxylation reactions to generate urolithins with different degrees of hydroxylation. Among urolithins, urolithins A and B are the most studied in the context of human health. Created with BioRender.com. Chemical structures created with Marvin JS (Chemaxon, Budapest, Hungary).</p>
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<p>Legumes like soybeans, chickpeas, beans, and peanuts are dietary sources of parent polyphenolic compounds (1) daidzein and (2) genistein (isoflavones). Upon ingestion, these polyphenolic compounds are poorly bioavailable and accumulate in the lower gastrointestinal tract. Bacterial species in the colon are involved in the catabolism of isoflavones. Main catabolic reactions are de-glycosylation to release the polyphenolic aglycone and sequential hydrogenation and dehydroxylation reactions, generating equols. The alternative pathway involving ring cleavage and generation of <span class="html-italic">O</span>-desmethylangolensin is not shown in this figure. Created with BioRender.com. Chemical structures created with Marvin JS (Chemaxon, Budapest, Hungary).</p>
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16 pages, 7466 KiB  
Article
Urolithin A Protects Hepatocytes from Palmitic Acid-Induced ER Stress by Regulating Calcium Homeostasis in the MAM
by Gayoung Ryu, Minjeong Ko, Sooyeon Lee, Se In Park, Jin-Woong Choi, Ju Yeon Lee, Jin Young Kim and Ho Jeong Kwon
Biomolecules 2024, 14(12), 1505; https://doi.org/10.3390/biom14121505 - 26 Nov 2024
Viewed by 734
Abstract
An ellagitannin-derived metabolite, Urolithin A (UA), has emerged as a potential therapeutic agent for metabolic disorders due to its antioxidant, anti-inflammatory, and mitochondrial function-improving properties, but its efficacy in protecting against ER stress remains underexplored. The endoplasmic reticulum (ER) is a cellular organelle [...] Read more.
An ellagitannin-derived metabolite, Urolithin A (UA), has emerged as a potential therapeutic agent for metabolic disorders due to its antioxidant, anti-inflammatory, and mitochondrial function-improving properties, but its efficacy in protecting against ER stress remains underexplored. The endoplasmic reticulum (ER) is a cellular organelle involved in protein folding, lipid synthesis, and calcium regulation. Perturbations in these functions can lead to ER stress, which contributes to the development and progression of metabolic disorders such as metabolic-associated fatty liver disease (MAFLD). In this study, we identified a novel target protein of UA and elucidated its mechanism for alleviating palmitic acid (PA)-induced ER stress. Cellular thermal shift assay (CETSA)-LC-MS/MS analysis revealed that UA binds directly to the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA), an important regulator of calcium homeostasis in mitochondria-associated ER membranes (MAMs). As an agonist of SERCA, UA attenuates abnormal calcium fluctuations and ER stress in PA-treated liver cells, thereby contributing to cell survival. The lack of UA activity in SERCA knockdown cells suggests that UA regulates cellular homeostasis through its interaction with SERCA. Collectively, our results demonstrate that UA protects against PA-induced ER stress and enhances cell survival by regulating calcium homeostasis in MAMs through SERCA. This study highlights the potential of UA as a therapeutic agent for metabolic disorders associated with ER stress. Full article
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<p>Effects of UA on cellular response, ER stress, and lipid accumulation in PA-treated hepatocytes. (<b>A</b>) The MTT assay was performed on HepG2 cells treated with various concentrations of UA (1–100 μM) for 24, 48, and 72 h to evaluate cell proliferation. (<b>B</b>) The MTT assay was used to measure the cell proliferation of HepG2 cells treated with PA (0.5 mM) and UA (20, 40 μM) for 24 h. (<b>C</b>) The Trypan blue exclusion assay was performed to evaluate the cell viability of HepG2 cells treated with PA (0.5 mM) and UA (20, 40 μM) for 24 h. (<b>D</b>) mCherry-CHOP stable HEK293 cells were treated with PA (0.5 mM) and UA (20, 40 μM) for 24 h, and mCherry fluorescence signals were measured. The expression of CHOP was visualized as a fluorescence signal and observed using confocal microscopy (scale bar: 10 μM). (<b>E</b>) HepG2 cells were treated with PA (0.5 mM) and UA (20, 40 μM) for 24 h, followed by staining of intracellular lipid droplets with BODIPY and observation via confocal microscopy (scale bar: 20 μM) (* <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.001, **** <span class="html-italic">p</span> &lt; 0.0001).</p>
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<p>CETSA-LC-MS/MS for the identification of the target protein of UA. (<b>A</b>) Overview of the CETSA-LC-MS/MS method. HEK293 cells were treated with DMSO (control) or UA (20 μM) and subjected to thermal treatment (55 °C or 60 °C). Proteins were then extracted, digested with trypsin, and labeled with TMT reagents. The labeled peptides were analyzed by HPLC and LC-MS/MS. (<b>B</b>) Schematic diagram of the target selection identification criteria of the UA process. (<b>C</b>) Heatmap of target candidates of UA localized in the ER and mitochondria. Proteins are clustered by their functions, as indicated on the left side of the heatmap.</p>
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<p>Validation of UA binding to SERCA. (<b>A</b>) Western blot analysis to evaluate the thermal stability of SERCA in HepG2 cells treated with UA (40 μM). (<b>B</b>) Comparison of the binding affinity between UA and two calcium-regulating target proteins: SERCA and CCDC47. HepG2 cells were treated with various concentrations of UA (1–100 μM), followed by isothermal CETSA at 52 °C. (<b>C</b>) The 2D diagram represents amino acids involved in UA binding to SERCA. (<b>D</b>) Predicted binding of UA to the actuator domain of SERCA, as visualized using Discovery Studio software 2018 (CDOCKER energy: −20.57 kcal/mol). (<b>E</b>) The 3D structure of the full-length SERCA protein (PDB: 7E7S), highlighting its four domains. (<b>F</b>) HEK293 cells were transfected with FLAG-SERCA(WT), FLAG-SERCA(R198A), or FLAG-SERCA(K234A) for 48 h and then treated with UA (40 μM). After heat treatment at 52 °C for 3 min, proteins were extracted and analyzed using a Western blot. (<b>G</b>) Measurement of ATPase activity of ER proteins extracted from LX2 cells. UA (20, 40 μM) and thapsigargin (0.1 μM) were each treated for 30 min before ATPase activity was assessed.</p>
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<p>Intracellular calcium levels in PA-treated HepG2 cells with UA. (<b>A</b>) HepG2 cells were transfected with the ER calcium indicator ER-LAR-GECO vector for 48 h, followed by treatment with UA (40 μM), CDN1163 (10 μM), or TG (0.1 μM) for 6 h (scale bar: 20 μm). (<b>B</b>) ER calcium levels were measured in HepG2 cells treated with PA (500 μM) for 6 h, either alone or co-treated with UA (40 μM) and CDN1163 (10 μM) (scale bar: 10 μm). (<b>C</b>) Cytosolic calcium levels were assessed using the Fluo-4-AM after 6 h of treatment with PA, either alone or co-treated with UA (40 μM) and CDN1163 (10 μM) (scale bar: 20 μm). (<b>D</b>) Mitochondrial calcium levels were determined using the Rhod-2-AM after 24 h of treatment with PA, either alone or co-treated with UA (40 μM) and CDN1163 (10 μM) (scale bar: 20 μm) (* <span class="html-italic">p</span> &lt; 0.05, *** <span class="html-italic">p</span> &lt; 0.001, **** <span class="html-italic">p</span> &lt; 0.0001).</p>
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<p>ER stress markers in PA-treated HepG2 cells with UA. (<b>A</b>) Western blot results showing changes in ER stress markers in HepG2 cells treated with PA. (<b>B</b>) HepG2 cells were treated with PA for 6 h in the absence or presence of UA (40 μM), CDN1163 (10 μM), and thapsigargin (0.1 μM). UA down-regulated the level of ER stress-related proteins. (<b>C</b>) HepG2 cells were treated with PA for 24 h in the absence or presence of UA (40μM), CDN1163 (10 μM), and thapsigargin (0.1 μM). UA down-regulated the level of CHOP (* <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, ns: not significant).</p>
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<p>Impact of <span class="html-italic">SERCA</span> knockdown on UA activity in PA-treated cells. (<b>A</b>–<b>C</b>) Following <span class="html-italic">SERCA</span> knockdown with si-SERCA for 24 h, cells were co-treated with PA and UA (40 μM) for 6 h. ER, cytosolic, and mitochondrial calcium levels were then measured using Mag-Fluo-4 AM, Fluo-4 AM, and Rhod-2 AM, respectively (scale bar: 40 μm). (<b>D</b>) <span class="html-italic">SERCA</span> knockdown using si-<span class="html-italic">SERCA</span> for 24 h confirmed the effect of UA (40 μM) on PA-induced ER stress protein levels, as shown by Western blot (* <span class="html-italic">p</span> &lt; 0.05, *** <span class="html-italic">p</span> &lt; 0.001, **** <span class="html-italic">p</span> &lt; 0.0001, ns: not significant).</p>
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<p>Schematic summary of the target proteins and mechanisms of action of UA. HepG2 cells stimulated with PA release ER calcium through IP<sub>3</sub>R, leading to ER stress. UA binds to SERCA, the ER calcium pump, replenishing ER calcium levels and maintaining calcium homeostasis. This mechanism helps protect the cells from stress-induced damage.</p>
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18 pages, 683 KiB  
Review
A Comprehensive Review of Pedunculagin: Sources, Chemistry, Biological and Pharmacological Insights
by Julia Snarska, Katarzyna Jakimiuk, Jakub W. Strawa, Tomasz M. Tomczyk, Monika Tomczykowa, Jakub P. Piwowarski and Michał Tomczyk
Int. J. Mol. Sci. 2024, 25(21), 11511; https://doi.org/10.3390/ijms252111511 - 26 Oct 2024
Viewed by 1001
Abstract
Pedunculagin is a widely abundant ellagitannin found in the plant kingdom, with a chemical structure featuring two hexahydroxydiphenoyl units linked to a glucose core. It has demonstrated various biological activities, including anti-cancer, anti-inflammatory, and anti-bacterial effects. This review aims to summarize the bioactivities, [...] Read more.
Pedunculagin is a widely abundant ellagitannin found in the plant kingdom, with a chemical structure featuring two hexahydroxydiphenoyl units linked to a glucose core. It has demonstrated various biological activities, including anti-cancer, anti-inflammatory, and anti-bacterial effects. This review aims to summarize the bioactivities, chemistry, and health-promoting properties of pedunculagin and plant preparations containing it. It is the first comprehensive summary covering pedunculagin’s chemistry, sources, metabolism, and other relevant research. The search databases were Google Scholar, EBSCO Discovery Service, REAXYS Database, SCILIT, SCOPUS, PubMed, MEDLINE, Web of Science, Wiley Online Library, Science Direct/ELSEVIER, WordCat, and Taylor and Francis Online. All the databases were methodically searched for data published from 1911 until 2024. Various biological effects were proven in vitro for pedunculagin; however, due to the limited availability of the isolated compound, they have not been so far directly confirmed on more advanced in vivo and clinical models. However, its bioactivity can be deduced from studies conducted for plant preparations containing this ellagitannin as a dominant constituent, consequently indicating beneficial health effects. Further studies are needed to determine the molecular mechanism of action following topical application as well as the contribution of gut microbiota postbiotic metabolites– urolithins–being formed following the oral ingestion of preparations containing pedunculagin. Full article
(This article belongs to the Special Issue Recent Research of Phytochemicals in Health and Disease)
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<p>Structural formula of pedunculagin.</p>
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<p>Metabolism of pedunculagin.</p>
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19 pages, 998 KiB  
Review
Harnessing Mitophagy for Therapeutic Advances in Aging and Chronic Neurodegenerative Diseases
by Devlina Ghosh and Alok Kumar
Neuroglia 2024, 5(4), 391-409; https://doi.org/10.3390/neuroglia5040026 - 15 Oct 2024
Cited by 1 | Viewed by 1793
Abstract
Introduction: Mitophagy, the selective degradation of damaged mitochondria, is essential for maintaining cellular health and function, particularly in high-energy demanding post-mitotic cells like neurons and in microglial cells. Aging results in impaired mitophagy, leading to mitochondrial dysfunction, oxidative stress, the release of damage-associated [...] Read more.
Introduction: Mitophagy, the selective degradation of damaged mitochondria, is essential for maintaining cellular health and function, particularly in high-energy demanding post-mitotic cells like neurons and in microglial cells. Aging results in impaired mitophagy, leading to mitochondrial dysfunction, oxidative stress, the release of damage-associated proteins (DAMPs), and neuroinflammation, which contribute to neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Mitochondrial dysfunction also contributes to the pathophysiology of depression by affecting synaptic plasticity, increasing neuroinflammation, and heightening oxidative stress. Aim: In this review, we summarize the recent developments on mechanisms of mitophagy, its therapeutic role in neuroprotection, and its implications in aging and neuroinflammation, complemented by future research requirements and implications. Result/Discussion: Therapeutic strategies that promote mitochondrial health, including enhancing mitophagy and mitochondrial biogenesis, show promise in treating neurodegenerative diseases and depression. Recent findings have emphasized therapeutic strategies to modulate mitophagy, such as pharmacological agents like urolithin A and rapamycin, genetic interventions such as PINK1/Parkin gene therapy, mitochondrial transplantation, and lifestyle and dietary interventions such as caloric restriction, exercise, and dietary supplements such as resveratrol and CoQ10. Key regulators of mitophagy, including the PINK1/Parkin pathway and various proteins like BNIP3, NIX, and FUNDC1, which facilitate the removal of damaged mitochondria, play a crucial role. Conclusions: These results highlight the importance of understanding the interplay between mitophagy and neuroinflammation and show that modulation of mitophagy can reduce oxidative stress and improve neuroinflammatory outcomes and depression in age-related neurodegenerative diseases. However, despite significant progress, challenges remain in understanding the underlying molecular mechanisms of mitophagy and its therapeutic regulation in aging disorders. Full article
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<p>The role of mitophagy in neurodegenerative diseases and therapeutic interventions. This figure illustrates the impact of impaired mitophagy on aging and neurodegenerative diseases. Impaired mitophagy leads to increased ROS, mitochondrial DNA mutations, oxidative stress, and neuroinflammation, contributing to neuronal damage and degeneration. The figure also outlines potential therapeutic interventions, including pharmacological agents, genetic techniques, and lifestyle modifications, aimed at enhancing mitophagy and improving neuronal health by reducing oxidative stress, decreasing protein aggregation, and promoting mitochondrial quality control.</p>
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15 pages, 17616 KiB  
Article
Activation of the Gut–Brain Interaction by Urolithin A and Its Molecular Basis
by Daiki Kubota, Momoka Sato, Miyako Udono, Akiko Kohara, Masatake Kudoh, Yuichi Ukawa, Kiichiro Teruya and Yoshinori Katakura
Nutrients 2024, 16(19), 3369; https://doi.org/10.3390/nu16193369 - 3 Oct 2024
Viewed by 1629
Abstract
Background: Urolithin A (Uro-A), a type of polyphenol derived from pomegranate, is known to improve memory function when ingested, in addition to its direct effect on the skin epidermal cells through the activation of longevity gene SIRT1. However, the molI ecular mechanism by [...] Read more.
Background: Urolithin A (Uro-A), a type of polyphenol derived from pomegranate, is known to improve memory function when ingested, in addition to its direct effect on the skin epidermal cells through the activation of longevity gene SIRT1. However, the molI ecular mechanism by which orally ingested Uro-A inhibits cognitive decline via the intestine remains unexplored. Objectives: This study aimed to evaluate the role of Uro-A in improving cognitive function via improved intestinal function and the effect of Uro-A on the inflammation levels and gene expression in hippocampus. Methods: Research to clarify the molecular basis of the functionality of Uro-A was also conducted. Results: The results demonstrated that Uro-A suppressed age-related memory impairment in Aged mice (C57BL/6J Jcl, male, 83 weeks old) by reducing inflammation and altering hippocampal gene expression. Furthermore, exosomes derived from intestinal cells treated with Uro-A and from the serum of Aged mice fed with Uro-A both activated neuronal cells, suggesting that exosomes are promising candidates as mediators of the Uro-A-induced activation of gut–brain interactions. Additionally, neurotrophic factors secreted from intestinal cells may contribute to the Uro-A-induced activation of gut–brain interactions. Conclusions: This study suggests that Uro-A suppresses age-related cognitive decline and that exosomes and other secreted factors may contribute to the activation of the gut–brain interaction. These findings provide new insights into the therapeutic potential of Uro-A for cognitive health. Full article
(This article belongs to the Special Issue Anti-Aging Activity of Food Components and Its Molecular Basis)
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<p>Schematic diagram of the experimental protocol.</p>
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<p>Effects of Uro-A on age-related memory impairment in Aged mice. (<b>A</b>) Comparison of exploration preference among Young, Aged-Ctrl, and Aged-Uro-A groups compared with that for the familiar object; (<b>B</b>) discrimination index compared with the Aged-Ctrl group (*** <span class="html-italic">p</span> &lt; 0.001) (value means ± SEM, <span class="html-italic">n</span> = 10). The circles indicate the respective data. n.s. shows not significant.</p>
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<p>Effects of Uro-A on age-related memory impairment in Aged mice. (<b>A</b>) Comparison of exploration preference among Young, Aged-Ctrl, and Aged-Uro-A groups compared with that for the familiar object; (<b>B</b>) discrimination index compared with the Aged-Ctrl group (*** <span class="html-italic">p</span> &lt; 0.001) (value means ± SEM, <span class="html-italic">n</span> = 10). The circles indicate the respective data. n.s. shows not significant.</p>
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<p>(<b>A</b>) Effects of Uro-A on age-related inflammation in Aged mice. Brain sections were incubated with primary antibodies for anti-Iba1, GFAP, and NeuN. Iba1 and GFAP were stained with Alexa Fluor 555 and NeuN with Alexa Fluor 488. After staining with Vectashield mounting medium, the tissue samples were observed under a fluorescence microscope. (<b>B</b>,<b>C</b>) Number of Iba1<sup>+</sup> and GFAP<sup>+</sup> cells per area, respectively (* <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01) (value means ± SEM, <span class="html-italic">n</span> = 10).</p>
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<p>Effects of Uro-A on gene expression in the hippocampus of Aged mice. (<b>A</b>) The changes in gene expression in the hippocampus of each mouse are shown as a heatmap. The genes were classified into four clusters (A–D) according to changes in gene expression. Genes expressed at low levels are shown in green and genes expressed at high levels are shown in red. (<b>B</b>) The expression of genes (SIRT1, mitochondrial transcription factor A (TFAM), Atp5d) in the hippocampus of Uro-A-fed mice analyzed by RNAseq. (<b>C</b>) The expression of genes (BDNF, TNF-α, and IL-1β) in the hippocampus of Uro-A-fed mice analyzed by RNAseq (* <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001) (value means ± SEM, <span class="html-italic">n</span> = 3).</p>
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<p>Cell supernatants of Caco-2 cells treated with Uro-A-activated SH-SY5Y cells for 2 days. Uro-A stock solution dissolved in DMSO was added at a dilution of 1/1000 to give a final concentration of 10–100 µM. In the DMSO group, the same volume of DMSO was added as at this time. DMSO-treated cells are the controls for all experiments. (<b>A</b>) Mitochondrial activity of SH-SY5Y cells treated with supernatant of Uro-A (10–100 µM)-treated Caco-2 cells. (<b>B</b>) Expression of SIRT1; (<b>C</b>) SIRT3; (<b>D</b>) NAMPT; (<b>E</b>) BDNF; and (<b>F</b>) PGC-1α in SH-SY5Y cells treated with the supernatant of 100 µM Uro-A-treated Caco-2 cells. (* <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001) (value means ± SEM, <span class="html-italic">n</span> = 3). Experiments were repeated three times, and representative data are shown.</p>
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<p>Cell supernatants of Caco-2 cells treated with Uro-A-activated SH-SY5Y cells for 2 days. Uro-A stock solution dissolved in DMSO was added at a dilution of 1/1000 to give a final concentration of 10–100 µM. In the DMSO group, the same volume of DMSO was added as at this time. DMSO-treated cells are the controls for all experiments. (<b>A</b>) Mitochondrial activity of SH-SY5Y cells treated with supernatant of Uro-A (10–100 µM)-treated Caco-2 cells. (<b>B</b>) Expression of SIRT1; (<b>C</b>) SIRT3; (<b>D</b>) NAMPT; (<b>E</b>) BDNF; and (<b>F</b>) PGC-1α in SH-SY5Y cells treated with the supernatant of 100 µM Uro-A-treated Caco-2 cells. (* <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001) (value means ± SEM, <span class="html-italic">n</span> = 3). Experiments were repeated three times, and representative data are shown.</p>
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<p>Functional evaluation of exosomes induced by Uro-A. (<b>A</b>) Effects of exosomes derived from Uro-A-treated Caco-2 cells on the activation of mitochondria; (<b>B</b>) effects of exosomes derived from serum of mice on the activation of mitochondria. (*** <span class="html-italic">p</span> &lt; 0.001) (value means ± SEM, <span class="html-italic">n</span> = 10). Experiments were repeated three times, and representative data are shown.</p>
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<p>Effects of Uro-A on the gene expression of secretory factors in Caco-2 cells. Expression of (<b>A</b>) BDNF; (<b>B</b>) NT-4; (<b>C</b>) CNTF; and (<b>D</b>) NGF in Caco-2 cells treated with 100 µM Uro-A. (<b>E</b>) BDNF level in the supernatant of Caco-2 treated with Uro-A was determined by ELISA (* <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01) (value means ± SEM, <span class="html-italic">n</span> = 3). Experiments were repeated three times, and representative data are shown.</p>
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24 pages, 6089 KiB  
Article
A Multi-Spectroscopic and Molecular Docking Analysis of the Biophysical Interaction between Food Polyphenols, Urolithins, and Human Serum Albumin
by Nevena Zelenović, Predrag Ristić, Natalija Polović, Tamara Todorović, Milica Kojadinović and Milica Popović
Molecules 2024, 29(18), 4474; https://doi.org/10.3390/molecules29184474 - 20 Sep 2024
Viewed by 891
Abstract
Secondary polyphenol metabolites, urolithins (UROs), have anti-oxidative, anti-inflammatory, and antidiabetic properties. Therefore, their biological activity relies on blood transport via human serum albumin (HSA) and tissue distribution. The main goal we set was to investigate the interaction between HSA and different URO (URO [...] Read more.
Secondary polyphenol metabolites, urolithins (UROs), have anti-oxidative, anti-inflammatory, and antidiabetic properties. Therefore, their biological activity relies on blood transport via human serum albumin (HSA) and tissue distribution. The main goal we set was to investigate the interaction between HSA and different URO (URO A, URO B, URO C, URO D, and glucuronidated URO A and B) using a combination of multi-spectroscopic instrumental and in silico approaches. The fluorescence spectroscopy revealed that URO can quench the naturally occurring fluorescence of HSA in a concentration-dependent manner. The HSA fluorescence was quenched by both a static and dynamic mechanism. The results showed that free UROs bind to HSA with higher affinity than their conjugated forms. CD spectroscopy and FTIR revealed that the alpha-helical structure of HSA is preserved. The calculated Gibbs free energy change indicates that the URO–HSA complex forms spontaneously. There is a single binding site on the HSA surface. The molecular docking results indicated that unconjugated Uro binds to Sudlow I, while their conjugation affects this binding site, so in the conjugated form, they bind to the cleft. Docking experiments indicate that all UROs are capable of binding to both thyroxine recognition sites of ligand-bound HSA proteins. Examining interactions under the following conditions (298 K, 303 K, and 310 K, pH 7.4) is of great importance for determining the pharmacokinetics of these bioactive compounds, as the obtained results can be used as a basis for modulating the potential dosing regimen. Full article
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Figure 1
<p>The chemical structures of urolithins are shown in the following order: (<b>A</b>) Urolithin A (URO A); (<b>B</b>) Urolithin B (URO B); (<b>C</b>) Urolithin A glucuronide (URO AG); (<b>D</b>) Urolithin B glucuronide (URO BG); (<b>E</b>) Urolithin C (URO C); (<b>F</b>) Urolithin D (URO D).</p>
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<p>The fluorescence emission spectra of HSA in the presence of increasing concentrations of URO (<b>A</b>) URO A (<b>B</b>) URO AG (<b>C</b>) URO B (<b>D</b>) URO BG (<b>E</b>) URO C (<b>F</b>) URO D at excitation λ<sub>ex</sub> = 280 nm. Conditions: pH = 7.4, T = 298 K. The HSA concentration was 3 × 10<sup>−6</sup> mol L<sup>−1</sup>, whereas the URO concentration was increased from 3 × 10<sup>−6</sup> mol L<sup>−1</sup> to 10 × 10<sup>−6</sup> mol L<sup>−1</sup> at an increment of 1 × 10<sup>−6</sup> mol L<sup>−1</sup>.</p>
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<p>Modified Stern–Volmer plots were generated to analyze the quenching of HSA by several compounds, namely (<b>A</b>) URO A (<b>B</b>) URO AG (<b>C</b>) URO B (<b>D</b>) URO BG (<b>E</b>) URO C (<b>F</b>) URO D, at a temperature of 298 K (green), 303 K (blue), and 310 K (black), and a pH value of 7.4. Error bars indicate standard errors of triplicate measurements.</p>
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<p>Double-log plots for the determination of binding constants, K<sub>b,</sub> and number of binding sites n for (<b>A</b>) URO A (<b>B</b>) URO AG (<b>C</b>) URO B (<b>D</b>) URO BG (<b>E</b>) URO C (<b>F</b>) URO D to HSA (3 × 10<sup>−6</sup> mol L<sup>−1</sup>) at 298 K, 303 K, and 310 K, and pH 7.4.</p>
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<p>van’t Hoff plot for the interaction of HSA with (<b>A</b>) URO A (<b>B</b>) URO AG (<b>C</b>) URo B (<b>D</b>) URO BG (<b>E</b>) URO C (<b>F</b>) URO D.</p>
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<p>The impact of addition of increasing URO concentration on the synchronous fluorescence spectra of HSA at Δλ = 60 nm: (<b>A</b>) URO A; (<b>B</b>) URO AG; (<b>C</b>) URO B; (<b>D</b>) URO BG; (<b>E</b>) URO C; (<b>F</b>) URO D. The HSA concentration was 3 × 10<sup>−6</sup> mol L<sup>−1</sup>, while the URO concentrations ranged 3 × 10<sup>−6</sup>–10 × 10<sup>−6</sup> mol L<sup>−1</sup> from top to bottom.</p>
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<p>Amide III region of FTIR spectra of HSA in the absence and presence of URO (at pH 7.4).</p>
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<p>Far-UV CD spectra of free URO A (6.0 × 10<sup>−6</sup> mol L<sup>−1</sup>; black line and 30.0 × 10<sup>−6</sup> mol L<sup>−1</sup>; red line), free HSA (3.0 × 10<sup>−6</sup> mol L<sup>−1</sup>; green line) and HSA-URO A complex (molar ratio 1:2; magenta line and 1:10; blue line) obtained at 298 K and pH 7.4.</p>
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<p>Three-dimensional bioactive conformations of URO A in FA9 (<b>A</b>), URO AG in FA9 (<b>B</b>), URO B in Sudlow’s site I (<b>C</b>), and URO BG in FA9 (<b>D</b>), URO C in FA9 (<b>E</b>), and URO D in FA9 (<b>F</b>), shown in ball and stick representation, with the corresponding molecular environment in the cavity. Amino acids that interact with ligands by non-covalent interactions (green lines) are shown in capped sticks style with a three-letter code and a sequence number in the protein sequence. The centroids of the aromatic rings are shown as ochre spheres. Amino acids and ligand atoms are represented by standardized CCDC colors (the gray color represents the urolithin carbon core, the red color represents the oxygen atoms, and the white color represents the hydrogen atoms from the hydroxyl group).</p>
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<p>Superimposed 3D bioactive conformations of URO A (dark blue), URO AG (pink), URO B (yellow), URO BG (light blue), URO C (dark green), and URO D (red) in FA-HSA FA8 (<b>A</b>), FA-HSA FA9/Cleft (<b>B</b>), heme-HSA FA8 (<b>C</b>), and heme-HSA FA9/Cleft (<b>D</b>) binding pockets. Space-fill models were used to represent heme and myristic acid molecules, while urolithin ligand molecules were shown in ball and stick style.</p>
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15 pages, 1745 KiB  
Article
Effect of Urolithin A on Bovine Sperm Capacitation and In Vitro Fertilization
by Manuela Jorge, Filipa C. Ferreira, Carla C. Marques, Maria C. Batista, Paulo J. Oliveira, F. Lidon, Sofia C. Duarte, José Teixeira and Rosa M. L. N. Pereira
Animals 2024, 14(18), 2726; https://doi.org/10.3390/ani14182726 - 20 Sep 2024
Viewed by 1030
Abstract
Reactive oxygen species (ROS) play a critical role in the functional competence of sperm cells. Conversely, excessive generation of ROS can impair sperm function, including their fertilization ability. Urolithin A (UA), a gut bacteria-derived metabolite produced from the transformation of ellagitannins, with anti-aging [...] Read more.
Reactive oxygen species (ROS) play a critical role in the functional competence of sperm cells. Conversely, excessive generation of ROS can impair sperm function, including their fertilization ability. Urolithin A (UA), a gut bacteria-derived metabolite produced from the transformation of ellagitannins, with anti-aging and antioxidant properties, was investigated for the first time in bovine sperm cells in the present study. Firstly, different doses of UA (0, 1, and 10 μM; 8–16 sessions) were used during the capacitation process of frozen-thawed bovine sperm. Sperm motility was assessed using optical microscopy and CASA. Sperm vitality (eosin-nigrosin), ROS, and ATP levels, as well as mitochondrial membrane potential (JC1) and oxygen consumption were evaluated. A second experiment to test the effect of different doses of UA (0, 1, and 10 μM; 9 sessions) in both the capacitation medium, as above, and the fertilization medium, was also implemented. The embryonic development and quality were evaluated. UA, at a concentration of 1 μM, significantly improved sperm movement quality (p < 0.03). There was a trend towards an increase in the oxygen consumption rate (OCR) of capacitated sperm with 1 μM and 10 μM UA supplementation. Moreover, an increase in ATP levels (p < 0.01) was observed, accompanied by a reduction in ROS levels at the higher UA concentration. These results suggest that UA may enhance spermatozoa mitochondrial function, modifying their metabolic activity while reducing the oxidative stress. Also, the number of produced embryos appears to be positively affected by UA supplementation, although differences between the bulls may have mitigated this effect. In conclusion, presented results further support previous findings indicating the potential therapeutic value of UA for addressing reproductive sub/infertility problems and improving ART outcomes. In addition, our results also reinforce the important bull effect on ART and that male sperm bioenergetic parameters should be used to predict spermatozoa functionality and developmental potential. Full article
(This article belongs to the Special Issue Advances in Animal Fertility Preservation—Second Edition)
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<p>Chemical structure of the urolithin A (UA; modified from <a href="https://pubchem.ncbi.nlm.nih.gov/compound/5488186" target="_blank">https://pubchem.ncbi.nlm.nih.gov/compound/5488186</a>, accessed on 13 September 2024).</p>
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<p>Experimental design of the second experiment to study the effect of UA in the process of the capacitation of bovine spermatozoa and fertilization of oocytes. UA was added to the capacitation medium (CAP) and/or the fertilization medium (FERT) at the concentration of 0 (control), 1, and 10 µM, totalizing seven groups. (A—Bull A; B—Bull B and C—Bull C).</p>
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<p>Effect of supplementation of the capacitation medium with UA (<b>A</b>) and of bull (<b>B</b>) on mitochondrial membrane potential (15 replicates). The data are presented as the mean value± standard error of the mean. CAPcontrol: capacitation medium without supplementation; CAP1: capacitation medium supplemented with 1 μM of UA; CAP10: capacitation medium supplemented with 10 μM of UA. Different letters indicate significant differences (<span class="html-italic">p</span> ≤ 0.05).</p>
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<p>Effect of urolithin A supplementation (0, 1, and 10 μM) and bull, and their interaction, on mitochondrial oxygen consumption rate, ATP levels, and ROS levels during the capacitation process of bovine sperm. (<b>A</b>–<b>C</b>) Basal oxygen consumption rate (OCR) was analyzed using the Seahorse XFe96 Extracellular Flux Analyzer. Data are means ± standard error of the mean of 21 replicates (5–8 for each bull), and results are expressed in pmol O<sub>2</sub><sup>−1</sup> min<sup>−1</sup> cell mass<sup>−1</sup>. (<b>D</b>–<b>F</b>) Mean fluorescence signal of the cellular oxidation product CM-H2DCFDA in bovine sperm of different bulls and in the presence or absence of UA supplementation (1 and 10 μM) during the capacitation process. Data are means ± standard error of the mean of 12 replicates (4 each bull), and results are expressed as CM-H2DCFDA fluorescence of sperm (1 × 10<sup>6</sup>). (<b>G</b>–<b>I</b>) intracellular ATP content in bovine sperm of different bulls and in the presence or absence of UA supplementation (1 and 10 μM) during the capacitation process. Data are means ± standard error of the mean of 12 replicates (4 each bull), and results are expressed as ATP levels per sperm (1 × 10<sup>6</sup>). *, **, *** and **** indicates differences at <span class="html-italic">p</span> &lt; 0.1, <span class="html-italic">p</span> &lt; 0.05, <span class="html-italic">p</span> ≤ 0.01, and <span class="html-italic">p</span> &lt; 0.001 respectively, compared to control, or bull A.; CAPcontrol: capacitation medium without supplementation; CAP1: capacitation medium supplemented with 1 μM of UA; CAP10: capacitation medium supplemented with 10 μM of UA. ## indicate significant differences (<span class="html-italic">p</span> &lt; 0.05) between Bull B and C.</p>
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<p>Effect of different concentrations of UA during capacitation and/or fertilization processes (<b>A</b>) and bull (<b>B</b>) on cleavage and embryo production rates (9 sessions). The data are presented as the mean value ± standard error of the mean and the number (n) of embryos. CAPcontrol: capacitation medium without supplementation; CAP1: capacitation medium supplemented with 1 μM of UA; CAP10: capacitation medium supplemented with 10 μM of UA. FERTcontrol: fertilization medium without supplementation; FERT1: fertilization medium supplemented with 1 μM of UA; FERT10: fertilization medium supplemented with 10 μM of UA. A, B and C represent the three bulls used in this study. * # indicate significant differences (<span class="html-italic">p</span> &lt; 0.05). Numbers above bars represent the number of produced embryos.</p>
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29 pages, 414 KiB  
Review
Pomegranate (Punica granatum L.) Extract Effects on Inflammaging
by Raffaele Cordiano, Luca Gammeri, Eleonora Di Salvo, Sebastiano Gangemi and Paola Lucia Minciullo
Molecules 2024, 29(17), 4174; https://doi.org/10.3390/molecules29174174 - 3 Sep 2024
Viewed by 3708
Abstract
Pomegranate is a notable source of nutrients, containing a considerable proportion of organic acids, polysaccharides, vitamins, fatty acids, and polyphenols such as flavonoids, phenolic acids, and tannins. It is also rich in nutritionally important minerals and chemical elements such as K, P, Na, [...] Read more.
Pomegranate is a notable source of nutrients, containing a considerable proportion of organic acids, polysaccharides, vitamins, fatty acids, and polyphenols such as flavonoids, phenolic acids, and tannins. It is also rich in nutritionally important minerals and chemical elements such as K, P, Na, Ca, Mg, and N. The presence of several bioactive compounds and metabolites in pomegranate has led to its incorporation into the functional food category, where it is used for its numerous therapeutic properties. Pomegranate’s bioactive compounds have shown antioxidant, anti-inflammatory, and anticancer effects. Aging is a process characterized by the chronic accumulation of damages, progressively compromising cells, tissues, and organs over time. Inflammaging is a chronic, subclinical, low-grade inflammation that occurs during the aging process and is linked to many age-related diseases. This review aims to summarize and discuss the evidence of the benefits of pomegranate extract and its compounds to slow the aging processes by intervening in the mechanisms underlying inflammaging. These studies mainly concern neurodegenerative and skin diseases, while studies in other fields of application need to be more practical. Furthermore, no human studies have demonstrated the anti-inflammaging effects of pomegranate. In the future, supplementation with pomegranate extracts, polyphenols, or urolithins could represent a valuable low-risk complementary therapy for patients with difficult-to-manage diseases, as well as a valid therapeutic alternative for the topical or systemic treatment of skin pathologies. Full article
(This article belongs to the Special Issue Plants Extractions in Health Care)
18 pages, 5712 KiB  
Article
Urolithin A Ameliorates the TGF Beta-Dependent Impairment of Podocytes Exposed to High Glucose
by Barbara Lewko, Milena Wodzińska, Agnieszka Daca, Agata Płoska, Katarzyna Obremska and Leszek Kalinowski
J. Pers. Med. 2024, 14(9), 914; https://doi.org/10.3390/jpm14090914 - 28 Aug 2024
Viewed by 834
Abstract
Increased activity of transforming growth factor-beta (TGF-β) is a key factor mediating kidney impairment in diabetes. Glomerular podocytes, the crucial component of the renal filter, are a direct target of TGF-β action, resulting in irreversible cell loss and progression of chronic kidney disease [...] Read more.
Increased activity of transforming growth factor-beta (TGF-β) is a key factor mediating kidney impairment in diabetes. Glomerular podocytes, the crucial component of the renal filter, are a direct target of TGF-β action, resulting in irreversible cell loss and progression of chronic kidney disease (CKD). Urolithin A (UA) is a member of the family of polyphenol metabolites produced by gut microbiota from ellagitannins and ellagic acid-rich foods. The broad spectrum of biological activities of UA makes it a promising candidate for the treatment of podocyte disorders. In this in vitro study, we investigated whether UA influences the changes exerted in podocytes by TGF-β and high glucose. Following a 7-day incubation in normal (NG, 5.5 mM) or high (HG, 25 mM) glucose, the cells were treated with UA and/or TGF-β1 for 24 h. HG and TGF-β1, each independent and in concert reduced expression of nephrin, increased podocyte motility, and up-regulated expression of b3 integrin and fibronectin. These typical-for-epithelial-to-mesenchymal transition (EMT) effects were inhibited by UA in both HG and NG conditions. UA also reduced the typically elevated HG expression of TGF-β receptors and activation of the TGF-β signal transducer Smad2. Our results indicate that in podocytes cultured in conditions mimicking the diabetic milieu, UA inhibits and reverses changes underlying podocytopenia in diabetic kidneys. Hence, UA should be considered as a potential therapeutic agent in podocytopathies. Full article
(This article belongs to the Section Disease Biomarker)
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<p>Ellagitannins (ETs) and ellagic acid (EA) are naturally occurring polyphenolic bioactive compounds found in fruits and seeds of various food plants. ETs are hydrolyzed to EA in the upper part of the gastrointestinal tract and further converted by microbiota in the large intestine into urolithins. Depending on individual microbiota composition, various urolithin isoforms are produced, of which urolithin A is the most common form [<a href="#B28-jpm-14-00914" class="html-bibr">28</a>]. In contrast to ETs and EA, urolithins are easily absorbed in the gut.</p>
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<p>The effect of UA on the TGF-β1 and HG-induced downregulation of nephrin: (<b>A</b>,<b>C</b>) Quantitative flow cytometry analysis of UA effect on nephrin expression at the podocyte surface (<b>A</b>) and total nephrin (<b>C</b>). Podocytes cultured for 7 d in normal (5.5 mM, NG) or high (25 mM, HG) glucose were incubated for 24 h with 5 ng/mL TGF-β1 and 10 µM UA, stained with phycoerythrin-conjugated antibody against the extracellular nephrin domain (<b>A</b>) or total nephrin (<b>C</b>) and analyzed by flow cytometry. (<b>B</b>,<b>D</b>) Representative histograms showing the effect of UA on surface (<b>B</b>) and total (<b>D</b>) nephrin expression. (<b>E</b>) Quantitative confocal microscopy analysis of total nephrin expression. (<b>F</b>) Representative confocal microscopy images of immunofluorescent staining against nephrin. Results show mean ± SEM. Student’s <span class="html-italic">t</span>-test and ANOVA test were used to calculate <span class="html-italic">p</span>-values. For (<b>A</b>,<b>C</b>) * <span class="html-italic">p</span> &lt; 0.05 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.05 vs. respective TGF-β1 and Control, *** <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, # <span class="html-italic">p</span> &lt; 0.01 vs. respective TGF-β1, and <span>$</span> <span class="html-italic">p</span> &lt; 0.05 vs. HG Control, @ <span class="html-italic">p</span> &lt; 0.05 vs. NG TGF-β1 (<span class="html-italic">n</span> = 3–5). For (<b>E</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.001 vs. HG Control, and &amp; <span class="html-italic">p</span> &lt; 0.001 vs. respective TGF-β1, # <span class="html-italic">p</span> &lt; 0.05 vs. HG Control. 553 cells were analyzed in two independent experiments. MFI: mean fluorescence intensity.</p>
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<p>Effects of UA on migratory capacity and expression of β3 integrin in podocytes exposed to TGF-β1 and HG. Podocytes cultured for 7 d in normal (5.5 mM, NG) or high (25 mM, HG) glucose were incubated for 24 h with 5 ng/mL TGF-β1 and/or 10 µM UA: (<b>A</b>) Representative image of the wound healing test. After making a scratch in the cell monolayer (time 0), the podocytes were incubated in indicated media for 24 h. (<b>B</b>) Quantification of wound healing assay (<span class="html-italic">n</span> = 4). (<b>C</b>) Representative immunoblot for integrin β3 expression; 30 µg protein samples from total cell lysates were subjected to Western blot analysis followed by quantitative densitometric analysis. (<b>D</b>) Quantification of Western blot analyses of β3 integrin expression (<span class="html-italic">n</span> = 3). (<b>E</b>) Representative confocal microscopy images of immunofluorescent staining against β3 integrin. (<b>F</b>) Quantitative confocal microscopy analysis of β3 integrin expression; 754 cells were analyzed in two independent experiments. Results show mean ± SEM. Student’s <span class="html-italic">t</span>-test, Mann–Whitney <span class="html-italic">U</span> test, and ANOVA were used to calculate <span class="html-italic">p</span>-values. * <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.001 vs. HG Control, # <span class="html-italic">p</span> &lt; 0.001 vs. respective TGF-β1, @ <span class="html-italic">p</span> &lt; 0.001 vs. NG TGF-β1.</p>
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<p>Modulation by UA of fibronectin expression in podocytes exposed to TGF-β1 and HG. Podocytes cultured for 7 d in normal (5.5 mM, NG) or high (25 mM, HG) glucose were incubated for 24 h with 5 ng/mL TGF-β1 and/or 10 µM UA: (<b>A</b>) Results of quantitative RT-PCR analysis for fibronectin. Relative levels of mRNA were normalized to β-actin (<span class="html-italic">n</span> = 4). (<b>B</b>) Quantification of Western blot analyses of fibronectin expression (<span class="html-italic">n</span> = 3–4). (<b>C</b>) Representative immunoblot for fibronectin expression; 30-µg protein samples from total cell lysates were subjected to Western blot analysis followed by quantitative densitometric analysis. (<b>D</b>) Representative confocal microscopy images of immunofluorescent staining showing fibronectin (red), F-actin (green), and counterstained with DAPI (blue). (<b>E</b>) Quantitative confocal microscopy analysis of fibronectin expression; 758 cells were analyzed in two independent experiments. Results show mean ± SEM. Student’s <span class="html-italic">t</span>-test, Mann–Whitney <span class="html-italic">U</span> test, and ANOVA test were used to calculate <span class="html-italic">p</span>-values. For (<b>A</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.01 vs. respective Control, @ <span class="html-italic">p</span> &lt; 0.01 vs. NG TGF-β1. For (<b>B</b>) * <span class="html-italic">p</span> &lt; 0.01 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.02 vs. respective TGF-β1, # <span class="html-italic">p</span> &lt; 0.02 vs. HG Control. For (<b>E</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. respective Control and TGF-β1, ** <span class="html-italic">p</span> &lt; 0.001 vs. HG Control.</p>
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<p>Effects of UA on the expression of TGF-β1 receptors TβRI and TβRII. Podocytes cultured for 7 d in normal (5.5 mM, NG) or high (25 mM, HG) glucose were incubated for 24 h with 5 ng/mL TGF-β1 and/or 10 µM UA: (<b>A</b>) Results of quantitative RT-PCR analysis for TβRI. Relative levels of mRNA were normalized to β-actin (<span class="html-italic">n</span> = 3). (<b>B</b>) Quantitative confocal microscopy analysis of TβRI expression; 810 cells were analyzed in two independent experiments. (<b>C</b>) Representative confocal microscopy images of immunofluorescent staining against TβRI. (<b>D</b>) Results of quantitative RT-PCR analysis for f TβRII. Relative levels of mRNA were normalized to β-actin (<span class="html-italic">n</span> = 3). (<b>E</b>) Quantitative confocal microscopy analysis of TβRII expression; 840 cells were analyzed in two independent experiments. (<b>F</b>) Representative confocal microscopy images of immunofluorescent staining against TβRII. Results show mean ± SEM. Student’s <span class="html-italic">t</span>-test and ANOVA test were used to calculate <span class="html-italic">p</span> values. For (<b>A</b>) * <span class="html-italic">p</span> &lt; 0.05 vs. respective Control, ** <span class="html-italic">p</span> &lt; 0.001 vs. respective Control, *** <span class="html-italic">p</span> &lt; 0.005 vs. NG Control. For (<b>B</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. respective Control, ** <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, # <span class="html-italic">p</span> &lt; 0.001 vs. TGF-β1, @ <span class="html-italic">p</span> &lt; 0.001 vs. NG TGF-β1. For (<b>D</b>) * <span class="html-italic">p</span> &lt; 0.05 vs. respective Control, # <span class="html-italic">p</span> &lt; 0.01 vs. UA. For (<b>E</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.001 vs. HG Control, # <span class="html-italic">p</span> &lt; 0.001 vs. respective TGF-β1 and UA, @ <span class="html-italic">p</span> &lt; 0.001 vs. NG TGF-β1.</p>
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<p>Effects of UA on Smad2-dependent signaling of TGF-β1. Podocytes cultured for 7 d in normal (5.5 mM, NG) or high (25 mM, HG) glucose were incubated for 24 h with 5 ng/mL TGF-β1 and/or 10 µM UA: (<b>A</b>) Representative immunoblots for expression of Smad2 and phospho-Smad2 (pSmad2); 30-µg protein samples from total cell lysates were subjected to Western blot analysis followed by quantitative densitometric analysis. (<b>B</b>) Quantification of Western blot analyses of pSmad2/Smad2 expression ratio (<span class="html-italic">n</span> = 3). (<b>C</b>) Quantitative confocal microscopy analysis of Smad2 expression; 550 cells were analyzed in two independent experiments. (<b>D</b>) Quantitative confocal microscopy analysis of pSmad2 expression; 550 cells were analyzed in two independent experiments. (<b>E</b>) Representative confocal microscopy images of immunofluorescent staining against Smad2. (<b>F</b>) Representative confocal microscopy images of immunofluorescent staining against pSmad2. Results show mean ± SEM. Student’s <span class="html-italic">t</span>-test and ANOVA test were used to calculate <span class="html-italic">p</span>-values. For (<b>B</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.03 vs. HG Control, *** <span class="html-italic">p</span> &lt; 0.01 vs. NG TGF-b1, # <span class="html-italic">p</span> &lt; 0.03 vs. HG TGF-b1. For (<b>C</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.01 vs. HG Control, *** <span class="html-italic">p</span> &lt; 0.001 vs. Control and TGF-b1. For (<b>D</b>) * <span class="html-italic">p</span> &lt; 0.001 vs. NG Control, ** <span class="html-italic">p</span> &lt; 0.001 vs. respective Control, # <span class="html-italic">p</span> &lt; 0.01 vs. respective TGF-b1.</p>
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<p>Proposed mechanisms of UA inhibition of HG-dependent and -independent EMT in podocytes.</p>
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60 pages, 1805 KiB  
Systematic Review
Mechanistic Insights into the Biological Effects and Antioxidant Activity of Walnut (Juglans regia L.) Ellagitannins: A Systematic Review
by Letiția Mateș, Roxana Banc, Flaviu Andrei Zaharie, Marius Emil Rusu and Daniela-Saveta Popa
Antioxidants 2024, 13(8), 974; https://doi.org/10.3390/antiox13080974 - 10 Aug 2024
Cited by 2 | Viewed by 2318
Abstract
Walnuts (Juglans regia L.) are an important source of ellagitannins. They have been linked to positive effects on many pathologies, including cardiovascular disorders, neurodegenerative syndromes, and cancer. The limited bioavailability of ellagitannins prevents them from reaching significant circulatory levels, despite their antioxidant, [...] Read more.
Walnuts (Juglans regia L.) are an important source of ellagitannins. They have been linked to positive effects on many pathologies, including cardiovascular disorders, neurodegenerative syndromes, and cancer. The limited bioavailability of ellagitannins prevents them from reaching significant circulatory levels, despite their antioxidant, anti-inflammatory, and chemopreventive properties. Urolithins are ellagitannin gut microbiota-derived metabolites. They have better intestinal absorption and may be responsible for the biological activities of ellagitannins. Recent evidence showed that walnut ellagitannins and their metabolites, urolithins, could have positive outcomes for human health. This study aims to synthesize the current literature on the antioxidant activity and mechanistic pathways involved in the therapeutic potential of walnut ellagitannins and their metabolites. In the eligible selected studies (n = 31), glansreginin A, pedunculagin, and casuarictin were the most prevalent ellagitannins in walnuts. A total of 15 urolithins, their glucuronides, and sulfate metabolites have been identified in urine, blood, feces, breast milk, and prostate tissue in analyzed samples. Urolithins A and B were associated with antioxidant, anti-inflammatory, cardioprotective, neuroprotective, anticarcinogenic, and anti-aging activities, both in preclinical and clinical studies. Despite the promising results, further well-designed studies are necessary to fully elucidate the mechanisms and confirm the therapeutic potential of these compounds in human health. Full article
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Figure 1

Figure 1
<p>PRISMA flow diagram of study selection.</p>
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<p>The main metabolites of ETs and EA formed after walnut <span class="html-italic">(J. regia</span> L.) intake by intestinal microbiota (created with BioRender.com).</p>
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<p>The mechanisms of ellagitannins, ellagic acid, and urolithins and their multiple beneficial health effects after walnut consumption (AGEs—advanced glycation end products; BDNF—brain-derived neurotrophic factor; CA2—carbonic anhydrase 2; CAT—catalase; CRC—colorectal cancer; CPS1—carbamoylphosphate synthetase; CREB—cAMP-response element binding protein; CSCs—cancer stem cells; EA—ellagic acid; ETs—ellagitannins; HOC—hippocampal occupancy score; HOMA-IR—Homeostatic Model Assessment for Insulin Resistance; ICAM-1—intracellular adhesion molecule 1; IL—interleukin; INF-γ—interferon gamma; LDL-c—low-density lipoprotein cholesterol; MDA—malondialdehyde; NAFLD—non-alcoholic fatty liver disease; NF-κB—nuclear factor kappa-light-chain-enhancer of activated B cells; NASH—non-alcoholic steatohepatitis; ORAC—oxygen radical absorbance capacity; PCa—prostate cancer; PKA—protein kinase A; ROS—reactive oxygen species; SCFA—short-chain fatty acids; SOD—superoxide dismutase; TG—triglycerides; TNFα—tumor necrosis factor-α; T-AOC—total antioxidant capacity; UM—urolithin metabotypes; Uros—urolithins; VCAM-1—vascular cell adhesion molecule 1; WAT—white adipose tissue; ↑—increases; ↓—decreases).</p>
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17 pages, 3613 KiB  
Article
Urolithin A Protects against Hypoxia-Induced Pulmonary Hypertension by Inhibiting Pulmonary Arterial Smooth Muscle Cell Pyroptosis via AMPK/NF-κB/NLRP3 Signaling
by Xinjie He, Zhinan Wu, Jinyao Jiang, Wenyi Xu, Ancai Yuan, Fei Liao, Song Ding and Jun Pu
Int. J. Mol. Sci. 2024, 25(15), 8246; https://doi.org/10.3390/ijms25158246 - 28 Jul 2024
Cited by 1 | Viewed by 1390
Abstract
Recent studies confirmed that pyroptosis is involved in the progression of pulmonary hypertension (PH), which could promote pulmonary artery remodeling. Urolithin A (UA), an intestinal flora metabolite of ellagitannins (ETs) and ellagic acid (EA), has been proven to possess inhibitory effects on pyroptosis [...] Read more.
Recent studies confirmed that pyroptosis is involved in the progression of pulmonary hypertension (PH), which could promote pulmonary artery remodeling. Urolithin A (UA), an intestinal flora metabolite of ellagitannins (ETs) and ellagic acid (EA), has been proven to possess inhibitory effects on pyroptosis under various pathological conditions. However, its role on PH remained undetermined. To investigate the potential of UA in mitigating PH, mice were exposed to hypoxia (10% oxygen, 4 weeks) to induce PH, with or without UA treatment. Moreover, in vitro experiments were carried out to further uncover the underlying mechanisms. The in vivo treatment of UA suppressed the progression of PH via alleviating pulmonary remodeling. Pyroptosis-related genes were markedly upregulated in mice models of PH and reversed after the administration of UA. In accordance with that, UA treatment significantly inhibited hypoxia-induced pulmonary arterial smooth muscle cell (PASMC) pyroptosis via the AMPK/NF-κB/NLRP3 pathway. Our results revealed that UA treatment effectively mitigated PH progression through inhibiting PASMC pyroptosis, which represents an innovative therapeutic approach for PH. Full article
(This article belongs to the Special Issue Signaling Pathways and Novel Therapies in Heart Disease)
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Figure 1
<p>Urolithin A attenuates the progression of hypoxia-induced PH. (<b>a</b>) Protocol for administration of UA (HX + UA) or vehicle (HX) to mice subjected to hypoxia or normoxia (NOR). (<b>b</b>) RVSP, mPAP, RVHI (RVHI = RV/LV + S), and body weight in mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 6–8 per group). (<b>c</b>) Representative photomicrographs of hematoxylin and eosin (H&amp;E) staining and elastin–van Gieson (EVG) staining of lung tissue from mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 6 per group). Scale bars: 50 μm. (<b>d</b>) Qualification of pulmonary vascular remodeling by percentage of vascular medial thickness to total vessel size for mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 6 per group). (<b>e</b>) Representative immunofluorescence staining of lung tissue for α-SMA (green, smooth muscle cells), vWF (red, endothelial cells) and DAPI (blue, nuclei) from mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 6 per group). Scale bars: 50 μm. (<b>f</b>) Qualification analysis of the α-SMA<sup>+</sup> or vWF<sup>+</sup> areas. ** <span class="html-italic">p</span> &lt; 0.01 compared to the NOR group, *** <span class="html-italic">p</span> &lt; 0.001 compared to the NOR group, # <span class="html-italic">p</span> &lt; 0.05 compared to the HX group, ## <span class="html-italic">p</span> &lt; 0.01 compared to the HX group.</p>
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<p>Urolithin A inhibited NLRP3-mediated pyroptosis pathway in hypoxia-induced PH mice lungs. (<b>a</b>,<b>b</b>) Western blotting analysis for the protein expression of NLRP3, GSDMD, N-GSDMD, IL-1β, and cleaved-Caspase-1 relative to β-actin from lungs of mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 6 per group). (<b>c</b>) Representative immunofluorescence staining of lung tissue for α-SMA (greens), Caspase-1 (red) and DAPI (blue) from mice exposed to hypoxia with UA or vehicle treatment (<span class="html-italic">n</span> = 6 per group). Scale bars: 50 μm. (<b>d</b>) Quantification of the α-SMA<sup>+</sup> Caspase-1<sup>+</sup> areas. (<b>e</b>) Representative TEM images of pulmonary arterial smooth muscle cells of mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 4 per group). Red arrows indicate the membrane oligomeric pores. Scale bars: 2 μm. * <span class="html-italic">p</span> &lt; 0.05 compared to the NOR group, ** <span class="html-italic">p</span> &lt; 0.01 compared to the NOR group, *** <span class="html-italic">p</span> &lt; 0.001 compared to the NOR group, # <span class="html-italic">p</span> &lt; 0.05 compared to the HX group, ## <span class="html-italic">p</span> &lt; 0.01 compared to the HX group.</p>
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<p>UA alleviated the proliferation and migration of hPASMCs. (<b>a</b>) Cell viability of hPASMCs exposed to hypoxia for varying durations (<span class="html-italic">n</span> = 6 per group). * <span class="html-italic">p</span> &lt; 0.05 compared to the 0 h group, ** <span class="html-italic">p</span> &lt; 0.01 compared to the 0 h group, *** <span class="html-italic">p</span> &lt; 0.001 compared to the 0 h group. (<b>b</b>) Cell viability of hPASMCs exposed to hypoxia for 48 h with different concentrations of UA (<span class="html-italic">n</span> = 6 per group). * <span class="html-italic">p</span> &lt; 0.05 compared to the 0 μM UA group, ** <span class="html-italic">p</span> &lt; 0.01 compared to the 0 μM UA group. (<b>c</b>) Representative images and (<b>d</b>) qualification analysis of wound confluency of hPASMCs (<span class="html-italic">n</span> = 3 per group). ** <span class="html-italic">p</span> &lt; 0.01 compared to the control group, *** <span class="html-italic">p</span> &lt; 0.001 compared to the control group, # <span class="html-italic">p</span> &lt; 0.05 compared to the hypoxia group, ### <span class="html-italic">p</span> &lt; 0.001 compared to the hypoxia group. (<b>e</b>) Representative images and (<b>f</b>) qualification analysis of cell counts of hPASMCs using Transwell assay (<span class="html-italic">n</span> = 3 per group). Scale bars: 100 μm. ** <span class="html-italic">p</span> &lt; 0.01 compared to the control group, # <span class="html-italic">p</span> &lt; 0.05 compared to the hypoxia group.</p>
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<p>UA attenuated hypoxia-induced pyroptosis in hPASMCs. (<b>a</b>,<b>b</b>) Western blotting analysis for the protein expression of NLRP3, GSDMD, N-GSDMD, IL-1β, and Caspase-1 relative to β-actin in hPASMCs exposed to hypoxia with or without UA treatment (<span class="html-italic">n</span> = 6 per group). (<b>c</b>) Representative immunofluorescence staining for α-SMA (greens), Caspase-1 (red) and DAPI (blue) in hPASMCs exposed to hypoxia with or without UA treatment (<span class="html-italic">n</span> = 3 per group). Scale bars: 50 μm. (<b>d</b>) Qualification analysis of the NLRP3<sup>+</sup> or Caspase-1<sup>+</sup> areas. ** <span class="html-italic">p</span> &lt; 0.01 compared to the control group, *** <span class="html-italic">p</span> &lt; 0.001 compared to the control group, # <span class="html-italic">p</span> &lt; 0.05 compared to the hypoxia group, ## <span class="html-italic">p</span> &lt; 0.01 compared to the hypoxia group.</p>
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<p>UA attenuated PASMC pyroptosis through inhibiting the NF-κB/NLRP3 signaling pathway. (<b>a</b>,<b>b</b>) Western blotting analysis for the protein expression of p-P65 relative to P65 and p-IκB-α relative to IκB-α in hPASMCs exposed to hypoxia with or without UA treatment (<span class="html-italic">n</span> = 6 per group). ** <span class="html-italic">p</span> &lt; 0.01 compared to the control group, # <span class="html-italic">p</span> &lt; 0.05 compared to the hypoxia group, ## <span class="html-italic">p</span> &lt; 0.01 compared to the hypoxia group. (<b>c</b>,<b>d</b>) Western blotting analysis for the protein expression of p-P65 relative to P65 and p-IκB-α relative to IκB-α from lungs of mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 6 per group). ** <span class="html-italic">p</span> &lt; 0.01 compared to the NOR group, # <span class="html-italic">p</span> &lt; 0.05 compared to the HX group.</p>
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<p>UA inhibited NF-κB/NLRP3 pathway via activating AMPK. (<b>a</b>) Molecular structure of UA. (<b>b</b>,<b>c</b>) The molecular docking models of UA with (<b>b</b>) AMPK-α1 and (<b>c</b>) AMPK-α2, respectively. The solid blue lines represent hydrogen bonds, the gray dotted lines represent hydrophobic effect, and the green dotted lines represent π-π stacking interaction. (<b>d</b>,<b>e</b>) Western blotting analysis for the protein expression of p-AMPK relative to β-actin in hPASMCs exposed to hypoxia with or without UA treatment (<span class="html-italic">n</span> = 6 per group). ** <span class="html-italic">p</span> &lt; 0.01 compared to the control group, # <span class="html-italic">p</span> &lt; 0.05 compared to the hypoxia group. (<b>f</b>,<b>g</b>) Western blotting analysis for the protein expression of p-AMPK relative to β-actin from lungs of mice exposed to normoxia (NOR) or hypoxia with UA (HX + UA) or vehicle (HX) treatment (<span class="html-italic">n</span> = 6 per group). ** <span class="html-italic">p</span> &lt; 0.01 compared to the NOR group, # <span class="html-italic">p</span> &lt; 0.05 compared to the HX group.</p>
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<p>The AMPK selective inhibitor Compound C hindered the protective effect of UA on hPASMCs. (<b>a</b>,<b>b</b>) Western blotting analysis for the protein expression of p-AMPK relative to β-actin in hPASMCs administered with different concentrations of Compound C (<span class="html-italic">n</span> = 3 per group). * <span class="html-italic">p</span> &lt; 0.05 compared to the 0μM Compound C group, *** <span class="html-italic">p</span> &lt; 0.001 compared to the 0 μM Compound C group, ns means nonsignificant. (<b>c</b>,<b>d</b>) Western blotting analysis for the protein expression of p-IκB-α relative to IκB-α and p-P65 relative to P65 in hPASMCs exposed to hypoxia with or without UA or Compound C treatment (<span class="html-italic">n</span> = 6 per group).(<b>e</b>,<b>f</b>) Western blotting analysis for the protein expression of NLRP3, N-GSDMD, IL-1β, and Caspase-1 relative to β-actin in hPASMCs exposed to hypoxia with or without UA or Compound C treatment (<span class="html-italic">n</span> = 6 per group). ** <span class="html-italic">p</span> &lt; 0.01 compared to the control group, *** <span class="html-italic">p</span> &lt; 0.001 compared to the control group, # <span class="html-italic">p</span> &lt; 0.05 compared to the hypoxia group, ## <span class="html-italic">p</span> &lt; 0.01 compared to the hypoxia group, ^ <span class="html-italic">p</span> &lt; 0.05 compared to the hypoxia + UA group, ^^ <span class="html-italic">p</span> &lt; 0.01 compared to the hypoxia + UA group.</p>
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<p>Urolithin A protects against hypoxia-induced pulmonary hypertension by inhibiting NF-κB/NLRP3-mediated PASMC pyroptosis via regulating AMPK signaling (created with BioRender.com). PASMC, pulmonary arterial smooth muscle cell; IL-1β, interleukin-1β; GSDMD, gasdermin D; NLRP3, NOD-like receptor (NLR) family pyrin domain-containing 3; AMPK, AMP-activated protein kinase.</p>
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36 pages, 8923 KiB  
Article
Discovery of Cell-Permeable Allosteric Inhibitors of Liver Pyruvate Kinase: Design and Synthesis of Sulfone-Based Urolithins
by Shazia Iqbal, Md. Zahidul Islam, Sajda Ashraf, Woonghee Kim, Amal A. AL-Sharabi, Mehmet Ozcan, Essam Hanashalshahaby, Cheng Zhang, Mathias Uhlén, Jan Boren, Hasan Turkez and Adil Mardinoglu
Int. J. Mol. Sci. 2024, 25(14), 7986; https://doi.org/10.3390/ijms25147986 - 22 Jul 2024
Viewed by 1326
Abstract
Metabolic dysfunction-associated fatty liver disease (MAFLD) presents a significant global health challenge, characterized by the accumulation of liver fat and impacting a considerable portion of the worldwide population. Despite its widespread occurrence, effective treatments for MAFLD are limited. The liver-specific isoform of pyruvate [...] Read more.
Metabolic dysfunction-associated fatty liver disease (MAFLD) presents a significant global health challenge, characterized by the accumulation of liver fat and impacting a considerable portion of the worldwide population. Despite its widespread occurrence, effective treatments for MAFLD are limited. The liver-specific isoform of pyruvate kinase (PKL) has been identified as a promising target for developing MAFLD therapies. Urolithin C, an allosteric inhibitor of PKL, has shown potential in preliminary studies. Expanding upon this groundwork, our study delved into delineating the structure-activity relationship of urolithin C via the synthesis of sulfone-based urolithin analogs. Our results highlight that incorporating a sulfone moiety leads to substantial PKL inhibition, with additional catechol moieties further enhancing this effect. Despite modest improvements in liver cell lines, there was a significant increase in inhibition observed in HepG2 cell lysates. Specifically, compounds 15d, 9d, 15e, 18a, 12d, and 15a displayed promising IC50 values ranging from 4.3 µM to 18.7 µM. Notably, compound 15e not only demonstrated a decrease in PKL activity and triacylglycerol (TAG) content but also showed efficient cellular uptake. These findings position compound 15e as a promising candidate for pharmacological MAFLD treatment, warranting further research and studies. Full article
(This article belongs to the Section Biochemistry)
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Graphical abstract

Graphical abstract
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<p>Metabolic Pathway and Key Players Involved in MAFLD.</p>
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<p>Structural basis of ellagic acid (1), urolithin C (2), urolithin D (3), and their synthetic derivative (4), along with the proposed design of sulfonamides and sultam derivatives featuring a substituted benzylamine ‘handle’ for the development of PKL inhibitors.</p>
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<p>Synthesis of sulfone-based urolithin C compounds.</p>
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<p>Synthesis of sulfone-based urolithin C analogs.</p>
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<p>(<b>a</b>) PKM CRISPR knock-out HepG2 WT cells were designed. HepG2 PKM CRISPR KO cells have PKL only. (<b>b</b>) Pyruvate kinase activity assay on HepG2 KO cells (PKL only) protein lysate. Generated pyruvate (O.D. value at 570 nm) was calculated as a percentile (%). (<b>c</b>) IC<sub>50</sub> value of PKL enzymatic activity inhibition for most active compounds. 30 µM, 10 µM, 3 µM, 1 µM, 300 nM, 30 nM, and untreated groups were tested on HepG2 KO cell lysate. (<b>d</b>) Pyruvate kinase activity assay on HepG2 KO cells after 20 µM compounds for 4 hr treatment. Generated pyruvate (O.D. value at 570 nm) was calculated as a percentile (%). Data are represented as mean ± SD, * <span class="html-italic">p</span> &lt; 0.05, Student’s <span class="html-italic">t</span>-test.</p>
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<p>(<b>a</b>) Pyruvate kinase activity on cells. PK activities were tested on 20 µM <b>15e</b> for 4 h treated HepG2 CRISPR PKM KO cells (<b>left</b>) and HepG2 WT (<b>right</b>). The generated pyruvate during the assay was visualized in the histogram. (<b>b</b>) CETSA assay for PKM2 and PKL. <b>15e</b> 2 h treated HepG2 WT cells had heat shock at 60 °C for 5 min, and soluble proteins were analyzed using western blot. (<b>c</b>) Cell permeable PKL inhibitor <b>15e</b> was used to treat the HepG2 WT DNL steatosis model for one week at 5 µM, 2.5 µM, 1.25 µM, and 0.625 µM. After one week, TAG contents and cell viability were measured. (<b>d</b>) Western blot analysis for <b>15e</b> treated one-week HepG2 WT steatosis model. Compound <b>15e</b> was used to treat the HepG2 DNL steatosis model at a 5 µM concentration. The band intensity of DNL-involved steatosis proteins was measured. Arrows indicate FASN and PKL, which decreased protein expression. Data are represented as mean ± SD, * <span class="html-italic">p</span> &lt; 0.05, Student’s <span class="html-italic">t</span>-test.</p>
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<p>Protein-ligand interaction diagram of compounds (<b>a</b>) <b>15d</b>, (<b>b</b>) <b>12d</b>, (<b>c</b>) <b>9d</b>, (<b>d</b>) <b>15e</b>, (<b>e</b>) <b>18a</b>, and (<b>f</b>) <b>15a</b> bound to the allosteric interface of PKLR; (<b>g</b>) presenting the docking pose of the above-mentioned six urolithin D derivatives.</p>
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<p>Protein-ligand interaction diagram of compounds (<b>a</b>) <b>15d</b>, (<b>b</b>) <b>12d</b>, (<b>c</b>) <b>9d</b>, (<b>d</b>) <b>15e</b>, (<b>e</b>) <b>18a</b>, and (<b>f</b>) <b>15a</b> bound to the allosteric interface of PKLR; (<b>g</b>) presenting the docking pose of the above-mentioned six urolithin D derivatives.</p>
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<p>Structural representation of biaryl sulfonamide (linear) analogs for SAR.</p>
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<p>Structural representation of Sultam (cyclic) analogs of urolithic C for SAR.</p>
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<p>Shows the SAR study, identifying the pharmacophoric features of urolithin C and newly designed molecules, along with their IC<sub>50</sub> values.</p>
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<p>Presents a concise summary of the observed structure-activity relationship (SAR) of the PKL inhibitors investigated in this study.</p>
Full article ">Scheme 1
<p>Synthesis of biaryl sulfonamides (with a benzyl group); reagents and conditions: (a) HSO<sub>3</sub>Cl, 0 °C, 15 min, 82%; (b) DIPEA, CH<sub>2</sub>Cl<sub>2</sub>, r.t., 1 h, 90%; (c) Pd (PPh<sub>3</sub>)<sub>4</sub>, toluene:EtOH:water/5:2:1, 120 °C, MW, 1 h, 72–92%; (d) BBr<sub>3</sub>, DCM, r.t., o/n, 52–75%.</p>
Full article ">Scheme 2
<p>Synthesis of biaryl sulfonamides (with a fluorobenzyl group); reagents and conditions: (a) HSO<sub>3</sub>Cl, 0 °C, 15 min, 82%; (b) DIPEA, CH<sub>2</sub>Cl<sub>2</sub>, r.t., 1 h, 82%; (c) Pd (PPh<sub>3</sub>)<sub>4</sub>, toluene:EtOH:water/5:2:1, 120 °C, MW, 1 h, 67–88%; (d) BBr<sub>3</sub>, DCM, r.t., o/n, 52–72%.</p>
Full article ">Scheme 3
<p>Synthesis of sultam derivatives of urolithin C (with benzyl group); Reagents and conditions: (a) DIPEA, CH<sub>2</sub>Cl<sub>2</sub>, r.t., 1 h, 90%; (b) Pd (PPh<sub>3</sub>)<sub>4</sub>, toluene:EtOH:water/5:2:1, 120 °C, MW, 1 h, 72–92%; (c) PIDA, I<sub>2</sub>, K<sub>2</sub>CO<sub>3</sub>, CH<sub>2</sub>Cl<sub>2</sub>, 35 °C, 30 min–3 h, 45–79%; (d) BBr<sub>3</sub>, DCM, r.t., o/n, 52–71%.</p>
Full article ">Scheme 4
<p>Synthesis of biaryl sulfonamides (with a fluorobenzyl group); reagents and conditions: (a) DIPEA, CH<sub>2</sub>Cl<sub>2</sub>, r.t., 1 h, 85%; (b) Pd (PPh<sub>3</sub>)<sub>4</sub>, toluene:EtOH:water/5:2:1, 120 °C, MW, 1 h, 67–88%; (c) PIDA, I<sub>2</sub>, K<sub>2</sub>CO<sub>3</sub>, CH<sub>2</sub>Cl<sub>2</sub>, 35 °C, 30 min–3 h, 55–70%; (d) BBr<sub>3</sub>, DCM, r.t., o/n, 55–68%.</p>
Full article ">Scheme 5
<p>Synthesis of sultam derivatives of urolithin C (without benzyl group); reagents and conditions: (a) DIPEA, CH<sub>2</sub>Cl<sub>2</sub>, r.t., 1 h, 90%; (b) Pd(PPh<sub>3</sub>)<sub>4</sub>, toluene:EtOH:water/5:2:1, 120 °C, MW, 1 h; (c) PIDA, I<sub>2</sub>, K<sub>2</sub>CO<sub>3</sub>, CH<sub>2</sub>Cl<sub>2</sub>, 35 °C, 30 min–3 h; (d) BBr<sub>3</sub>, DCM, r.t., o/n, and MsOH, r.t., 1 h.</p>
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16 pages, 3354 KiB  
Article
Effect of Urolithin A on the Improvement of Circadian Rhythm Dysregulation in Intestinal Barrier Induced by Inflammation
by Yao Du, Xinyue Chen, Susumu Kajiwara and Kanami Orihara
Nutrients 2024, 16(14), 2263; https://doi.org/10.3390/nu16142263 - 13 Jul 2024
Cited by 1 | Viewed by 2112
Abstract
Circadian rhythm plays an important role in intestinal homeostasis and intestinal immune function. Circadian rhythm dysregulation was reported to induce intestinal microbiota dysbiosis, intestinal barrier disruption, and trigger intestinal inflammation. However, the relationship between intestinal microbiota metabolites and the circadian rhythm of the [...] Read more.
Circadian rhythm plays an important role in intestinal homeostasis and intestinal immune function. Circadian rhythm dysregulation was reported to induce intestinal microbiota dysbiosis, intestinal barrier disruption, and trigger intestinal inflammation. However, the relationship between intestinal microbiota metabolites and the circadian rhythm of the intestinal barrier was still unclear. Urolithin A (UA), a kind of intestinal microbial metabolite, was selected in this study. Results showed UA influenced on the expression rhythm of the clock genes BMAL1 and PER2 in intestinal epithelial cells. Furthermore, the study investigated the effects of UA on the expression rhythms of clock genes (BMAL1 and PER2) and tight junctions (OCLN, TJP1, and CLND1), all of which were dysregulated by inflammation. In addition, UA pre-treatment by oral administration to female C57BL/6 mice showed the improvement in the fecal IgA concentrations, tight junction expression (Clnd1 and Clnd4), and clock gene expression (Bmal1 and Per2) in a DSS-induced colitis model induced using DSS treatment. Finally, the Nrf2-SIRT1 signaling pathway was confirmed to be involved in UA’s effect on the circadian rhythm of intestinal epithelial cells by antagonist treatment. This study also showed evidence that UA feeding showed an impact on the central clock, which are circadian rhythms in SCN. Therefore, this study highlighted the potential of UA in treating diseases like IBD with sleeping disorders by improving the dysregulated circadian rhythms in both the intestinal barrier and the SCN. Full article
(This article belongs to the Special Issue Dietary Interventions for Functional Gastrointestinal Disorders)
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Figure 1

Figure 1
<p>The gene expression of clock genes in Caco-2 cells. The mRNA expression rhythm of <span class="html-italic">BMAL1</span> in Caco-2 cells (<b>A</b>). The baseline (<b>B</b>), amplitude (<b>C</b>), and acrophase (<b>D</b>) of <span class="html-italic">BMAL1</span> mRNA expression rhythm in Caco-2 cells. The mRNA expression rhythm of <span class="html-italic">PER2</span> in Caco-2 cells (<b>E</b>). The baseline (<b>F</b>), amplitude (<b>G</b>), and acrophase (<b>H</b>) of <span class="html-italic">PER2</span> mRNA expression rhythm in Caco-2 cells. Each point represents mean ± SEM, n = 4. Gray represents the vehicle control group while pink (40 μM) and red (100 μM) represent the UA treatment groups. Representative data from two independent trials were shown. **** <span class="html-italic">p</span> &lt; 0.0001, unpaired one-way ANOVA between Vehicle, 40UA, 100UA.</p>
Full article ">Figure 2
<p>The mRNA expression of clock genes in Caco-2 cells. The mRNA expression rhythm of <span class="html-italic">BMAL1</span> (<b>A</b>). The baseline (<b>B</b>), amplitude (<b>C</b>), and acrophase (<b>D</b>) of <span class="html-italic">BMAL1</span> mRNA expression rhythm in Caco-2 cells. The mRNA expression rhythm of <span class="html-italic">PER2</span> (<b>E</b>). The baseline (<b>F</b>), amplitude (<b>G</b>), and acrophase (<b>H</b>) of <span class="html-italic">PER2</span> mRNA expression rhythm in Caco-2 cells. Each point represents mean ± SEM, n = 3. Representative data from two independent trial were shown. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, unpaired one-way ANOVA between Vehicle, TNF-α + IL-17A, TNF-α + IL-17A + 40UA, and TNF-α + IL-17A + 100UA.</p>
Full article ">Figure 3
<p>The mRNA expression of tight junction genes in Caco-2 cells. The mRNA expression rhythm of <span class="html-italic">OCLN</span> and <span class="html-italic">CLDN1</span> (<b>A</b>,<b>D</b>). The baseline (<b>B</b>) and amplitude (<b>C</b>) of <span class="html-italic">OCLN</span> mRNA expression rhythm in Caco-2 cells. The baseline (<b>E</b>) and amplitude (<b>F</b>) of <span class="html-italic">CLDN1</span> mRNA expression rhythm in Caco-2 cells. Each point represents mean ± SEM, n = 3. Representative data from two independent trials were shown. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, unpaired one-way ANOVA between Vehicle, TNF-α + IL-17A, TNF-α + IL-17A + 40UA, and TNF-α + IL-17A + 100UA.</p>
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<p>The fecal concentration of IgA before and under DSS treatment. The fecal expression rhythm of IgA before DSS (<b>A</b>) and under DSS (<b>D</b>). The total fecal IgA concentration (<b>C</b>). The baseline (<b>B</b>) of IgA concentration rhythm before DSS treatment. The baseline (<b>E</b>) of IgA concentration rhythm under DSS. Each point represents mean ± SEM, n = 4, n refers to number of animals. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01 unpaired t-test between Vehicle and UA.</p>
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<p>The mRNA expression of clock genes and tight junction genes in mice colon samples. The mRNA expression rhythm of <span class="html-italic">Bmal1</span> (<b>A</b>) and <span class="html-italic">Per2</span> (<b>B</b>). The acrophase (<b>C</b>) of <span class="html-italic">Bmal1</span> mRNA expression rhythm in the colon. The mRNA expression rhythm of <span class="html-italic">Tjp1</span> (<b>D</b>). The baseline (<b>E</b>) and amplitude (<b>F</b>) of <span class="html-italic">Tjp1</span> mRNA expression rhythm in the colon. The mRNA expression rhythm of <span class="html-italic">Cldn1</span> (<b>G</b>). The baseline (<b>H</b>) and amplitude (<b>I</b>) of <span class="html-italic">Cldn1</span> mRNA expression rhythm in the colon. The mRNA expression rhythm of <span class="html-italic">Cldn4</span> (<b>J</b>). The baseline (<b>K</b>) and amplitude (<b>L</b>) of <span class="html-italic">Cldn4</span> mRNA expression rhythm in the colon. Each point represents mean ± SEM, n = 3–5, n refers to number of animals, four mice (DSS group CT2 n = 2, UA group CT0 n = 2) were removed because of death after DSS treatment. * <span class="html-italic">p</span> &lt; 0.05, unpaired <span class="html-italic">t</span>-test between Vehicle and UA.</p>
Full article ">Figure 6
<p>The mRNA expression of <span class="html-italic">Bmal1</span> and <span class="html-italic">Per2</span> in the SCN. The mRNA expression rhythm of <span class="html-italic">Bmal1</span> (<b>A</b>). The baseline (<b>B</b>), amplitude (<b>C</b>), and acrophase (<b>D</b>) of <span class="html-italic">Bmal1</span> mRNA expression rhythm in the SCN. The mRNA expression rhythm of <span class="html-italic">Per2</span> (<b>E</b>). The baseline (<b>F</b>), amplitude (<b>G</b>), and acrophase (<b>H</b>) of <span class="html-italic">Per2</span> mRNA expression rhythm in the SCN. Each point represents mean ± SEM, n = 3, n refers to number of animals. * <span class="html-italic">p</span> &lt; 0.05, unpaired <span class="html-italic">t</span>-test between Vehicle and UA.</p>
Full article ">Figure 7
<p>The mRNA expression of <span class="html-italic">BMAL1</span>, <span class="html-italic">PER2</span>, and <span class="html-italic">CLDN1</span> in co-culture system after Nrf2 antagonist treatment. The mRNA expression rhythm of <span class="html-italic">BMAL1</span> in the co-culture system (<b>A</b>). The baseline (<b>B</b>), amplitude (<b>C</b>), and acrophase (<b>D</b>) of <span class="html-italic">BMAL1</span> mRNA expression rhythm in the co-culture system. The mRNA expression rhythm of <span class="html-italic">PER2</span> in the co-culture system (<b>E</b>). The baseline (<b>F</b>), amplitude (<b>G</b>), and acrophase (<b>H</b>) of <span class="html-italic">PER2</span> mRNA expression rhythm in the co-culture system. The mRNA expression rhythm of <span class="html-italic">CLDN1</span> in the co-culture system (<b>I</b>). The baseline (<b>J</b>), amplitude (<b>K</b>) of <span class="html-italic">CLDN1</span> mRNA expression rhythm in the co-culture system. Each point represents mean ± SEM, n = 3. Representative data from two independent trials were shown. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.001, **** <span class="html-italic">p</span> &lt; 0.0001 unpaired one-way ANOVA between TNF-α + IL-17A, TNF-α + IL-17A + ML385, TNF-α + IL-17A + 100UA, and TNF-α + IL-17A + 100UA + ML385.</p>
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36 pages, 1446 KiB  
Review
Urolithins and Their Precursors Ellagic Acid and Ellagitannins: Natural Sources, Extraction and Methods for Their Determination
by Christiana Mantzourani, Eleni Kakouri, Konstantinos Palikaras, Petros A. Tarantilis and Maroula G. Kokotou
Separations 2024, 11(6), 174; https://doi.org/10.3390/separations11060174 - 2 Jun 2024
Cited by 1 | Viewed by 2929
Abstract
In the present review, we discuss the occurrence of ellagitannins (ETs) and ellagic acid (EA) and methods for their isolation from plant materials. We summarize analytical methods, including high-performance liquid chromatography–ultraviolet (HPLC–UV) and liquid chromatography–mass spectrometry (LC–MS), for the determination of ETs, EA [...] Read more.
In the present review, we discuss the occurrence of ellagitannins (ETs) and ellagic acid (EA) and methods for their isolation from plant materials. We summarize analytical methods, including high-performance liquid chromatography–ultraviolet (HPLC–UV) and liquid chromatography–mass spectrometry (LC–MS), for the determination of ETs, EA and their bioactive metabolites urolithins (Uros) in samples of plant and food origin, as well as in biological samples, such as plasma, urine and feces. In addition, the current interest in the bioactivities of Uros is discussed in brief. Full article
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Figure 1

Figure 1
<p>Structures of ETs found in pomegranate (punicalin and punicalagin) and their conversion to EA.</p>
Full article ">Figure 2
<p>Catabolic pathway for the conversion of ellagic acid into urolithins.</p>
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