Walnut polyphenol metabolites, urolithins A and B, inhibit the expression of the prostate-specific antigen and the androgen receptor in prostate cancer cells

Urolithin C suppresses colorectal cancer progression via the AKT/mTOR pathway

Urolithin families are gut-microbial metabolites of ellagic acid (EA). Although urolithin A (UA) and urolithin B (UB) were reported to have antiproliferative activities in cancer cells, the role and related mechanisms of urolithin C (UC) in colorectal cancer (CRC) have not yet been clarified. In this study, we assess the antitumor activities of UC in vitro and in vivo and further explore the underlying mechanisms in CRC cell lines. We found that UC inhibited the proliferation and migration of CRC cells, induced apoptosis, and arrested the cell cycle at the G2/M phase in vitro, and UC inhibited tumor growth in a subcutaneous transplantation tumor model in vivo. Mechanically, UC blocked the activation of the AKT/mTOR signaling pathway by decreasing the expression of Y-box binding protein 1(YBX1). The AKT agonist SC79 could reverse the suppression of cell proliferation in UC-treated CRC cells. In conclusion, our research revealed that UC could prevent the progression of CRC by blocking AKT/mTOR signaling, suggesting that it may have potential therapeutic values.

Groundnut and tree nuts: a comprehensive review on their lipid components, phytochemicals, and nutraceutical properties

The health benefits of nut consumption have been extensively demonstrated in observational studies and intervention trials. Besides the high nutritional value, countless evidences show that incorporating nuts into the diet may contribute to health promotion and prevention of certain diseases. Such benefits have been mostly and certainly attributed not only to their richness in healthy lipids (plentiful in unsaturated fatty acids), but also to the presence of a vast array of phytochemicals, such as polar lipids, squalene, phytosterols, tocochromanols, and polyphenolic compounds. Thus, many nut chemical compounds apply well to the designation "nutraceuticals," a broad umbrella term used to describe any food component that, in addition to the basic nutritional value, can contribute extra health benefits. This contribution analyses the general chemical profile of groundnut and common tree nuts (almond, walnut, cashew, hazelnut, pistachio, macadamia, pecan), focusing on lipid components and phytochemicals, with a view on their bioactive properties. Relevant scientific literature linking consumption of nuts, and/or some of their components, with ameliorative and/or preventive effects on selected diseases - such as cancer, cardiovascular, metabolic, and neurodegenerative pathologies - was also reviewed. In addition, the bioactive properties were analyzed in the light of known mechanistic frameworks.

Urolithin B protects PC12 cells against glutamate-induced toxicity

BACKGROUND

The involvement of malfunctioning glutamate systems in various central nervous system (CNS) disorders is widely acknowledged. Urolithin B, known for its neuroprotective and antioxidant properties, has shown potential as a therapeutic agent for these disorders. However, little is known about its protective effects against glutamate-induced toxicity in PC12 cells. Therefore, in this study, for the first time we aimed to investigate the ability of Urolithin B to reduce the cytotoxic effects of glutamate on PC12 cells.

METHODS

Different non-toxic concentrations of urolithin B were applied to PC12 cells for 24 h before exposure to glutamate (10 mM). The cells were then analyzed for cell viability, intracellular reactive oxygen species (ROS), cell cycle arrest, apoptosis, and the expression of Bax and Bcl-2 genes.

RESULTS

The results of MTT assay showed that glutamate at a concentration of 10 mM and urolithin B at a concentration of 114 μM can reduce PC12 cell viability by 50%. However, urolithin B at non-toxic concentrations of 4 and 8 μM significantly reduced glutamate-induced cytotoxicity (p < 0.01). Interestingly, treatment with glutamate significantly enhanced the intracellular ROS levels and apoptosis rate in PC12 cells, while pre-treatment with non-toxic concentrations of urolithin B significantly reduced these cytotoxic effects. The results also showed that pre-treatment with urolithin B can decrease the Bax (p < 0.05) and increase the Bcl-2 (p < 0.01) gene expression, which was dysregulated by glutamate.

CONCLUSIONS

Taken together, urolithin B may play a protective role through reducing oxidative stress and apoptosis against glutamate-induced toxicity in PC12 cells, which merits further investigations.

Dual targeting in prostate cancer with phytoconstituents as a potent lead: a computational approach for novel drug discovery

Prostate Cancer (PCa) is an abnormal cell growth within the prostate. This condition is the second most widespread malignancy in elderly males and one of the most frequently diagnosed life-threatening conditions. The Androgen receptor signaling pathway played a crucial role in the initiation and spread to increase the risk of PCa. Hence, targeting the AR receptor signaling pathway is a key strategy for a therapeutic plan for PCa. Our study focuses on recognizing potential inhibitors for dual targeting in PCa by using the in-silico approach. In this study, we target the two enzymes that are CYP17A1 (3RUK) and 5α-reductase (3G1R) responsible for PCa, with the help of phytoconstituents. The natural plant contains various phytochemical types produced from secondary metabolites and used as a medical treatment. The in-silico investigation of phytoconstituents and enzymes was done by approaching molecular docking, ADMET analysis, and high-level molecular dynamic simulation used to assess the stability and binding affinities of the protein-ligand complex. Some phytoconstituents, such as Peonidin, Pelargonidin, Malvidin and Berberine show complex has good molecular interaction with protein. The reliability of the docking scores was examined using a molecular dynamic simulation, which revealed that the complex remained stable throughout the simulation, which ranged from 0 to 200 ns. The selected hits may be effective against CYP17A1 (3RUK) and 5α-reductase (3G1R) (PCa) using a computer-aided drug design (CADD) method, which further enables researchers for upcoming in-vivo and in-vitro research, according to our in-silico approach.Communicated by Ramaswamy H. Sarma.

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

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

Health functions and related molecular mechanisms of ellagitannin-derived urolithins

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

Urolithin B suppresses osteoclastogenesis via inhibiting RANKL-induced signalling pathways and attenuating ROS activities

Osteoporosis (OP) has severely affected human health, which is characterized by abnormal differentiation of osteoclasts. Urolithin B (UB), as a potential natural drug, has been reported to exhibit numerous biological activities including antioxidant and anti‐inflammatory but its effects on OP, especially on RANKL‐stimulated osteoclast formation and activation, are still understood. In our study, we have demonstrated for the first time that UB inhibits RANKL‐induced osteoclast differentiation and explored its potential mechanisms of action. The RAW264.7 cells were cultured and induced with RANKL followed by UB treatment. Then, the effects of UB on mature osteoclast differentiation were evaluated by counting tartrate‐resistant acid phosphatase (TRAP)‐positive multinucleated cells and F‐actin ring analysis. Moreover, the effects of UB on RANKL‐induced reactive oxygen species (ROS) were measured by 2′, 7′‐dichlorodihydrofluorescein diacetate (DCFH‐DA) staining. Further, we explored the potential mechanisms of these downregulation effects by performing Western blotting and quantitative RT‐PCR examination. We found that UB represses osteoclastogenesis, F‐actin belts formation, osteoclast‐specific gene expressions and ROS activity in a time‐ and concentration‐dependent manner. Mechanistically, UB attenuates intracellular ROS levels by upregulation of Nrf2 and other ROS scavenging enzymes activation. Furthermore, UB also inhibited RANKL‐induced NF‐κB, MAPK and Akt signalling pathway and suppressed expression of c‐Fos and nuclear factor of activated T cells 1 (NFATc1), which is the master transcription factor of osteoclast differentiation. Taken together, our findings confirm that UB is a polyphenolic compound that can be a potential therapeutic treatment for osteoclast‐related bone diseases such as osteoporosis.

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

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

Urolithins: The Colon Microbiota Metabolites as Endocrine Modulators: Prospects and Perspectives

Selective estrogen receptor modulators (SERMs) have been used in hormone related disorders, and their role in clinical medicine is evolving. Tamoxifen and raloxifen are the most commonly used synthetic SERMs, and their long-term use are known to create side effects. Hence, efforts have been directed to identify molecules which could retain the beneficial effects of estrogen, at the same time produce minimal side effects. Urolithins, the products of colon microbiota from ellagitannin rich foodstuff, have immense health benefits and have been demonstrated to bind to estrogen receptors. This class of compounds holds promise as therapeutic and nutritional supplement in cardiovascular disorders, osteoporosis, muscle health, neurological disorders, and cancers of breast, endometrium, and prostate, or, in essence, most of the hormone/endocrine-dependent diseases. One of our findings from the past decade of research on SERMs and estrogen modulators, showed that pomegranate, one of the indirect but major sources of urolithins, can act as SERM. The prospect of urolithins to act as agonist, antagonist, or SERM will depend on its structure; the estrogen receptor conformational change, availability and abundance of co-activators/co-repressors in the target tissues, and also the presence of other estrogen receptor ligands. Given that, urolithins need to be carefully studied for its SERM activity considering the pleotropic action of estrogen receptors and its numerous roles in physiological systems. In this review, we unveil the possibility of urolithins as a potent SERM, which we are currently investigating, in the hormone dependent tissues.

Dietary polyphenol and microbiota interactions in the context of prostate health

Recent data strongly indicate a relationship between prostate health and gut microbiota, in which composition and physiological function strictly depend on dietary patterns. The bidirectional interplay of foods containing polyphenols, such as ellagitannins, condensed tannins, lignans, isoflavones, and prenylated flavonoids with human gut microbiota, has been proven to contribute to their impact on prostate health. Considering the attributed role of dietary polyphenols in the prevention of prostate diseases, this paper aims to critically review the studies concerning the influence of polyphenols' postbiotic metabolites on processes associated with the pathophysiology of prostate diseases. Clinical, in vivo, and in vitro studies on polyphenols have been juxtaposed with the current knowledge regarding their pharmacokinetics, microbial metabolism, and potential interactions with microbiota harboring different niches of the human organism. Directions of future research on dietary polyphenols regarding their interaction with microbiota and prostate health have been indicated.

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

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

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

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

Urolithin A induces cell cycle arrest and apoptosis by inhibiting Bcl-2, increasing p53-p21 proteins and reactive oxygen species production in colorectal cancer cells

Colorectal cancer (CRC) is the second most common gastrointestinal cancer globally. Prevention of tumor cell proliferation and metastasis is vital for prolonging patient survival. Polyphenols provide a wide range of health benefits and prevention from cancer. In the gut, urolithins are the major metabolites of polyphenols. The objective of our study was to elucidate the molecular mechanism of the anticancer effect of urolithin A (UA) on colorectal cancer cells. UA was found to inhibit the cell proliferation of CRC cell lines in a dose-dependent and time-dependent manner in HT29, SW480, and SW620 cells. Exposure to UA resulted in cell cycle arrest in a dose-dependent manner along with alteration in the expression of cell cycle-related protein. Treatment of CRC cell lines with UA resulted in the induction of apoptosis. Treatment of HT29, SW480, and SW620 with UA resulted in increased expression of the pro-apoptotic proteins, p53 and p21. Similarly, UA treatment inhibited the anti-apoptotic protein expression of Bcl-2. Moreover, exposure of UA induced cytochrome c release and caspase activation. Furthermore, UA was found to generate reactive oxygen species (ROS) production in CRC cells. These findings indicate that UA possesses anticancer potential and may be used therapeutically for the treatment of CRC.

Urolithin A Prevents Focal Cerebral Ischemic Injury via Attenuating Apoptosis and Neuroinflammation in Mice

Neuroinflammation contributes to neuronal death in cerebral ischemia. Urolithin A (UA), a gut microbial metabolite of ellagic acid, has emerged as a potential anti-inflammatory agent. However, its roles and precise mechanisms in stroke remain unknown. Here we found that UA treatment ameliorated infarction, neurological deficit scores, and spatial memory deficits after cerebral ischemia. Furthermore, UA significantly reduced neuron loss and promoted neurogenesis after ischemic stroke. We also found that UA attenuated apoptosis by regulating apoptotic-related proteins. Meanwhile, UA treatment inhibited glial activation via affecting inflammatory signaling pathways, specifically by enhancing cerebral AMPK and IκBa activation while decreasing the activation of Akt, P65NFκB, ERK, JNK, and P38MAPK. Our findings reveal a key role of UA against ischemic stroke through modulating apoptosis and neuroinflammation in mice.

The Crosstalk between Prostate Cancer and Microbiota Inflammation: Nutraceutical Products Are Useful to Balance This Interplay?

The human microbiota shows pivotal roles in urologic health and disease. Emerging studies indicate that gut and urinary microbiomes can impact several urological diseases, both benignant and malignant, acting particularly on prostate inflammation and prostate cancer. Indeed, the microbiota exerts its influence on prostate cancer initiation and/or progression mechanisms through the regulation of chronic inflammation, apoptotic processes, cytokines, and hormonal production in response to different pathogenic noxae. Additionally, therapies' and drugs' responses are influenced in their efficacy and tolerability by microbiota composition. Due to this complex potential interconnection between prostate cancer and microbiota, exploration and understanding of the involved relationships is pivotal to evaluate a potential therapeutic application in clinical practice. Several natural compounds, moreover, seem to have relevant effects, directly or mediated by microbiota, on urologic health, posing the human microbiota at the crossroad between prostatic inflammation and prostate cancer development. Here, we aim to analyze the most recent evidence regarding the possible crosstalk between prostate, microbiome, and inflammation.

The Facts about Food after Cancer Diagnosis: A Systematic Review of Prospective Cohort Studies

Nutritional guidelines suggest specific energy and protein requirements for patients with cancer. However, cancer patients, often malnourished, use self-made or web-based diets to ameliorate the prognosis of their disease. This review aimed to investigate the associations between post-diagnostic diet and prognostic outcomes in cancer patients. A systematic literature search was performed in Pubmed and Web of Science databases from inception to 30 October 2019, based on fixed inclusion and exclusion criteria. The risk of bias was assessed. A total of 29 prospective studies was identified. Breast (n = 11), colorectal (n = 9), prostate (n = 8) cancers are the most studied. Low- fat diet, healthy quality diet, regular consumption of fiber such as vegetables and high-quality protein intake are beneficial while Western diet (WD) and high consumption of saturated fats could be associated with a higher risk of mortality. Bladder (n = 1), gynecological (n = 1), lung, stomach, and pancreatic cancers still remain almost unexplored. This systematic review suggested that detrimental dietary patterns such as WD should be avoided but none of the food categories (meat, dairy products) should be eliminated in cancer patients' diet. Further large prospective studies are needed to assess the role of post-diagnostic diet in patients with cancer.

An overview of phytochemicals and potential health-promoting properties of black walnut

Black walnut contains a diverse mixture of bioactive compounds, including phenolics, phytosterols, unsaturated fatty acids, and tocopherols potentially important to human health.

The Polyphenols as Potential Agents in Prevention and Therapy of Prostate Diseases

In recent years, the progress of science and medicine greatly has influenced human life span and health. However, lifestyle habits, like physical activity, smoking cessation, moderate alcohol consumption, diet, and maintaining a normal body weight represent measures that greatly reduce the risk of various diseases. The type of diet is very important for disease development. Numerous epidemiological clinical data confirm that longevity is linked to predominantly plant-based diets and it is related to a long life; whereas the western diet, rich in red meat and fats, increases the risk of oxidative stress and thus the risk of developing various diseases and pre-aging. This review is focused on the bioavailability of polyphenols and the use of polyphenols for the prevention of prostate diseases. Special focus in this paper is placed on the isoflavonoids and flavan-3-ols, subgroups of polyphenols, and their protective effects against the development of prostate diseases.

Comprehensive analysis of chestnut tannins by reversed phase and hydrophilic interaction chromatography coupled to ion mobility and high resolution mass spectrometry

In this study, we report a methodology based on reversed phase LC (RP-LC) and hydrophilic interaction chromatography (HILIC) separations coupled to ion mobility (IM) and high resolution mass spectrometry (HR-MS) for the detailed analysis of hydrolysable tannins. The application of this approach to the analysis of an industrial chestnut (Castanea sativa, wood chips) tannin extract is demonstrated. A total of 38 molecular species, including a large number or isomers, were identified in this sample based on HR-MS^(E) and UV absorption spectral information as well as retention behaviour in both separation modes. In total, 128 and 90 isomeric species were resolved by RP- and HILIC-LC-IM-TOF-MS, respectively. The combination of low- and high collision energy mass spectral data with complementary chromatographic separations allowed tentative and putative identification of twenty molecular species, comprising 78 isomers, in chestnut for the first time. Ion mobility resolved six new dimeric and trimeric vescalagin conformers with unique arrival (drift) times, including new conformers of roburin A-D which were not separated using either RP-LC or HILIC. HILIC was found to be the preferred separation mode for the analysis of vescalagin derivatives, while RP-LC is preferred for the analysis of ellagitannins with a cyclic glucose core. For the complete separation of the galloyl glucose species, comprehensive HILIC × RP-LC separation would be required.

Metabolomics reveals diet-derived plant polyphenols accumulate in physiological bone

Plant-derived secondary metabolites consumed in the diet, especially polyphenolic compounds, are known to have a range of positive health effects. They are present in circulation after ingestion and absorption and can be sequestered into cells within particular organs, but have rarely been investigated systematically in osteological tissues. However, a small number of polyphenols and similar molecules are known to bind to bone. For example alizarin, a plant derived anthraquinone and tetracycline (a naturally occurring antibiotic), are both absorbed into bone from circulation during bone formation and are used to monitor mineralization in osteological studies. Both molecules have also been identified serendipitously in archaeological human bones derived from natural sources in the diet. Whether an analogous mechanism of sequestration extends to additional diet-derived plant-polyphenols has not previously been systematically studied. We investigated whether a range of diet-derived polyphenol-like compounds bind to bone using untargeted metabolomics applied to the analysis of bone extracts from pigs fed an acorn-based diet. We analysed the diet which was rich in ellagitannins, extracts from the pig bones and surrounding tissue, post-mortem. We found direct evidence of multiple polyphenolic compounds in these extracts and matched them to the diet. We also showed that these compounds were present in the bone but not surrounding tissues. We also provide data showing that a range of polyphenolic compounds bind to hydroxyapatite in vitro. The evidence for polyphenol sequestration into physiological bone, and the range and specificity of polyphenols in human and animal diets, raises intriguing questions about potential effects on bone formation and bone health. Further studies are needed to determine the stability of the sequestered molecules post-mortem but there is also potential for (palaeo)dietary reconstruction and forensic applications.

Molecular Mechanisms and Bioavailability of Polyphenols in Prostate Cancer

Prostate cancer is the one of the most frequently diagnosed cancers among men over the age of 50. Several lines of evidence support the observation that polyphenols have preventive and therapeutic effects in prostate cancer. Moreover, prostate cancer is ideal for chemoprevention due to its long latency. We propose here an equilibrated lifestyle with a diet rich in polyphenols as prophylactic attempts to slow down the progression of localized prostate cancer or prevent the occurrence of the disease. In this review, we will first summarize the molecular mechanisms of polyphenols in prostate cancer with a focus on the antioxidant and pro-oxidant effects, androgen receptors (AR), key molecules involved in AR signaling and their transactivation pathways, cell cycle, apoptosis, angiogenesis, metastasis, genetic aspects, and epigenetic mechanisms. The relevance of the molecular mechanisms is discussed in light of current bioavailability data regarding the activity of polyphenols in prostate cancer. We also highlight strategies for improving the bioavailability of polyphenols. We hope that this review will lead to further research regarding the bioavailability and the role of polyphenols in prostate cancer prevention and treatment.

In vivoformed metabolites of polyphenols and their biological efficacy

The metabolites of polyphenols are antioxidant, anti-inflammatory and anticancer agents. Being bioavailable, they may play an important role in preventing degenerative diseases.

Natural Products to Fight Cancer: A Focus on Juglans regia

Even if cancer represents a burden for human society, an exhaustive cure has not been discovered yet. Low therapeutic index and resistance to pharmacotherapy are two of the major limits of antitumour treatments. Natural products represent an excellent library of bioactive molecules. Thus, tapping into the natural world may prove useful in identifying new therapeutic options with favourable pharmaco-toxicological profiles. Juglans regia, or common walnut, is a very resilient tree that has inhabited our planet for thousands of years. Many studies correlate walnut consumption to beneficial effects towards several chronic diseases, such as cancer, mainly due to the bioactive molecules stored in different parts of the plant. Among others, polyphenols, quinones, proteins, and essential fatty acids contribute to its pharmacologic activity. The present review aims to offer a comprehensive perspective about the antitumour potential of the most promising compounds stored in this plant, such as juglanin, juglone, and the ellagitannin-metabolites urolithins or deriving from walnut dietary intake. All molecules and a chronic intake of the fruit provide tangible anticancer effects. However, the scarcity of studies on humans does not allow results to be conclusive.

The effects of urolithins on the response of prostate cancer cells to non-steroidal antiandrogen bicalutamide

BACKGROUND

Urolithins are bioavailable products of gut microbiota metabolism of ellagitannins. Their biological activity includes anti-cancer effects.

PURPOSE

The aim of this study was to explore the effects of urolithins on prostate cancer cells and activity of clinically used anti-androgen, bicalutamide.

METHODS

Prostate cancer cells were treated with urolithin A, urolithin B, urolithin C or their combinations with bicalutamide. Cell proliferation was determined by DNA fluorescence with Hoechst 33258. The combination index method was used to examine interactions. Apoptosis and androgen receptor (AR) localization were analysed by flow cytometry. Prostate specific antigen (PSA) secretion was measured by ELISA.

RESULTS

Urolithins inhibited proliferation of LNCaP prostate cancer cells. The mixtures of bicalutamide with uroA and uroB had additive anti-proliferative effect. All tested urolithins induced apoptosis of LNCaP cells. However, the combinations of bicalutamide with urolithin A and urolithin B had attenuated pro-apoptotic activity. UroA and uroC decreased DHT-induced PSA secretion. In contrast, uroB impaired PSA lowering effect of bicalutamide. UroA, individually and in combination with bicalutamide, promoted cytoplasmic localization of AR.

CONCLUSION

Urolithins might contribute to chemopreventive activity of ellagitannin rich preparations. Our results support use of ellagitannin rich preparations in prostate cancer chemoprevention, but advise caution in their potential use in complementary therapy of prostate cancer. The differences in activity profiles of urolithins indicate that possible health benefits and interactions will depend on the type of produced ellagitannins metabolite.

Dietary Walnuts Protect Against Obesity-Driven Intestinal Stem Cell Decline and Tumorigenesis

Obesity can negatively impact intestinal homeostasis, and increase colon cancer risk and related mortality. Thus, given the alarmingly high rates of obesity in the US and globally, it is critical to identify practical strategies that can break the obesity-cancer link. Walnuts have been increasingly recognized to mitigate cancer risk, and contain many bioactive constituents with antioxidant and anti-inflammatory properties that could potentially counteract pathways thought to be initiators of obesity-related cancer. Therefore, the purpose of this study was to determine if walnuts could preserve intestinal homeostasis, and attenuate tumorigenesis and growth in the context of obesity and a high calorie diet. To this end, we studied effects of walnuts on these parameters under different dietary conditions in wildtype mice, two independent Apc models (Apc^1638N/+ and Apc^Δ14), and in MC38 colon cancer cells in vivo, respectively. Walnuts did not alter the metabolic phenotype or intestinal morphology in normal mice fed either a low-fat diet (LFD), LFD with 6% walnuts (LFD+W), high-fat diet (HFD), or HFD with 7.6% walnuts (HFD+W). However, walnuts did lead to a significant reduction in circulating CCL5 and preserved intestinal stem cell (ISC) function under HFD-fed conditions. Furthermore, walnuts reduced tumor multiplicity in Apc^1638N/+ male HFD+W animals, as compared to HFD controls (3.7 ± 0.5 vs. 2.5 ± 0.3; P = 0.015), tended to reduce the number of adenocarcinomas (0.67 ± 0.16 vs. 0.29 ± 0.12; P = 0.07), and preferentially limited tumor growth in Apc^Δ14 male mice (P = 0.019) fed a high-calorie western-style diet. In summary, these data demonstrate that walnuts confer significant protection against intestinal tumorigenesis and growth and preserve ISC function in the context of a high-calorie diet and obesity. Thus, these data add to the accumulating evidence connecting walnuts as a potentially effective dietary strategy to break the obesity-colon cancer link.

Phytochemical profile and biological activity of Juglans regia

Juglans regia Linn. (Juglandaceae), popularly known as English or Persian walnut, is a valuable medicinal plant with a potency to cure various diseases in traditional medicine. Since ancient time, different local ethnic groups have used various part of J. regia for a wide array of ailments including helminthiasis, diarrhea, sinusitis, stomach ache, arthritis, asthma, eczema, scrofula, skin disorders, diabetes mellitus, anorexia, thyroid dysfunction, cancer and infectious diseases. Biological activities of J. regia have been reported in several peer review journals and scientific attention is increasing. The present review attempts to provide comprehensive information on plant description, ethnobotanical use, toxicity, phytochemical profile, pharmacology, clinical studies and current research prospective of the J. regia. Currently, there is an immense interest on isolation/identification of active constituents from walnut and screening those active compounds for pharmacological activities. In addition, researchers are performing clinical trials as well as screening various solvent extracts or fractions of J. regia in several animal diseases models to identify promising therapeutic benefits. In the present work, we review the latest information based on published scientific investigations of J. regia.

Health benefits of walnut polyphenols: An exploration beyond their lipid profile

Walnuts are commonly found in our diet and have been recognized for their nutritious properties for a long time. Traditionally, walnuts have been known for their lipid profile, which has been linked to a wide array of biological properties and health-promoting effects. In addition to essential fatty acids, walnuts contain a variety of other bioactive compounds, such as vitamin E and polyphenols. Among common foods and beverages, walnuts represent one of the most important sources of polyphenols, hence their effect over human health warrants attention. The main polyphenol in walnuts is pedunculagin, an ellagitannin. After consumption, ellagitannins are hydrolyzed to release ellagic acid, which is converted by gut microflora to urolithin A and other derivatives such as urolithins B, C, and D. Ellagitannins possess well known antioxidant and anti-inflammatory bioactivity, and several studies have assessed the potential role of ellagitannins against disease initiation and progression, including cancer, cardiovascular, and neurodegenerative diseases. The purpose of this review is to summarize current available information relating to the potential effect of walnut polyphenols in health maintenance and disease prevention.

Diverse Phytochemicals and Bioactivities in the Ancient Fruit and Modern Functional Food Pomegranate (Punica granatum)

Having served as a symbolic fruit since ancient times, pomegranate (Punica granatum) has also gained considerable recognition as a functional food in the modern era. A large body of literature has linked pomegranate polyphenols, particularly anthocyanins (ATs) and hydrolyzable tannins (HTs), to the health-promoting activities of pomegranate juice and fruit extracts. However, it remains unclear as to how, and to what extent, the numerous phytochemicals in pomegranate may interact and exert cooperative activities in humans. In this review, we examine the structural and analytical information of the diverse phytochemicals that have been identified in different pomegranate tissues, to establish a knowledge base for characterization of metabolite profiles, discovery of novel phytochemicals, and investigation of phytochemical interactions in pomegranate. We also assess recent findings on the function and molecular mechanism of ATs as well as urolithins, the intestinal microbial derivatives of pomegranate HTs, on human nutrition and health. A better understanding of the structural diversity of pomegranate phytochemicals as well as their bioconversions and bioactivities in humans will facilitate the interrogation of their synergistic/antagonistic interactions and accelerate their applications in dietary-based cancer chemoprevention and treatment in the future.

Prebiotic nut compounds and human microbiota

Nut consumption is clearly related to human health outcomes. Its beneficial effects have been mainly attributed to nut fatty acid profiles and content of vegetable protein, fiber, vitamins, minerals, phytosterols and phenolics. However, in this review we focus on the prebiotics properties in humans of the non-bioaccessible material of nuts (polymerized polyphenols and polysaccharides), which provides substrates for the human gut microbiota and on the formation of new bioactive metabolites and the absorption of that may partly explain the health benefits of nut consumption.

Urolithin A shows anti-atherosclerotic activity via activation of class B scavenger receptor and activation of Nef2 signaling pathway

BACKGROUND

This study investigates the therapeutic potential of urothelin A in attenuating atherosclerotic lesion in wistar rat models and explore the role of Scavenger receptor-class B type I (SR-BI) and activation of Nrf-2 singling pathway.

METHODS

Wistar rats (n=48) were feed with high cholesterol diet supplemented with Vitamin D3 and subjected to balloon injury of the aorta. Three days prior to the aortal injury, rats (n=16) were administered urothelin A (3mg/kg/d; po). Positive control were rats receiving high cholesterol diet and balloon injury of the aorta (n=16). The sham group (n=16) consisted of rats fed on basal diet. After twelve weeks blood was collected from all animals for estimation of lipid and angiotensin II (Ang II) levels along, subsequently all animals were sacrificed and morphologic analysis of the aorta was performed. Expression of SR-BI and phosphorylated extracellular signal regulated kinase 1/2 (p-ERK1/2) protein were evaluated by Western blot.

RESULTS

After twelve weeks of treatment with urolithin A, there was a significant decrease in the plasma lipid and Ang II levels and improvement of aortic lesion compared with the sham group. There was an increased expression of SR-BI and inhibition of p-ERK1/2 (p<0.05). The expression of SR-BI was inversely correlated with levels of Ang II.

CONCLUSION

From the results it can be safely concluded that administration of urolithin A attenuates atherosclerosis via upregulation of SR-BI expression and inhibition of p-ERK1/2 levels.

Triptolide Inhibits the AR Signaling Pathway to Suppress the Proliferation of Enzalutamide Resistant Prostate Cancer Cells

Enzalutamide is a second-generation androgen receptor (AR) antagonist for the treatment of metastatic castration-resistant prostate cancer (mCRPC). Unfortunately, AR dysfunction means that resistance to enzalutamide will eventually develop. Thus, novel agents are urgently needed to treat this devastating disease. Triptolide (TPL), a key active compound extracted from the Chinese herb Thunder God Vine (Tripterygium wilfordii Hook F.), possesses anti-cancer activity in human prostate cancer cells. However, the effects of TPL against CRPC cells and the underlying mechanism of any such effect are unknown. In this study, we found that TPL at low dose inhibits the transactivation activity of both full-length and truncated AR without changing their protein levels. Interestingly, TPL inhibits phosphorylation of AR and its CRPC-associated variant AR-V7 at Ser515 through XPB/CDK7. As a result, TPL suppresses the binding of AR to promoter regions in AR target genes along with reduced TFIIH and RNA Pol II recruitment. Moreover, TPL at low dose reduces the viability of prostate cancer cells expressing AR or AR-Vs. Low-dose TPL also shows a synergistic effect with enzalutamide to inhibit CRPC cell survival in vitro, and enhances the anti-cancer effect of enzalutamide on CRPC xenografts with minimal side effects. Taken together, our data demonstrate that TPL targets the transactivation activity of both full-length and truncated ARs. Our results also suggest that TPL is a potential drug for CRPC, and can be used in combination with enzalutamide to treat CRPC.

Gallic acid, a phenolic compound, exerts anti-angiogenic effects via the PTEN/AKT/HIF-1α/VEGF signaling pathway in ovarian cancer cells

Gallic acid (GA), a polyphenol, is widely found in numerous fruits and vegetables, particularly in hickory nuts. In the present study, we found that gallic acid, a natural phenolic compound isolated from fruits and vegetables, had a more potent growth inhibitory effect on two ovarian cancer cell lines, OVCAR-3 and A2780/CP70, than the effect on a normal ovarian cell line, IOSE-364. These results demonstrated that GA selectively inhibits the growth of cancer cells. Gene expression was examined by ELISA and western blot analysis, and gene pathways were examined by luciferase assay. It was found that GA inhibited VEGF secretion and suppressed in vitro angiogenesis in a concentration-dependent manner. GA downregulated AKT phosphorylation as well as HIF-1α expression but promoted PTEN expression. The luciferase assay results suggest that the PTEN/AKT/HIF-1α pathway accounts for the inhibitory effect of GA on VEGF expression and in vitro angiogenesis. These findings provide strong support for the high potential of GA in the prevention and therapy of ovarian cancer.

Fat intake after prostate cancer diagnosis and mortality in the Physicians' Health Study

PURPOSE

Diet after prostate cancer diagnosis may impact disease progression. We hypothesized that consuming saturated fat after prostate cancer diagnosis would increase risk of mortality, and consuming vegetable fat after diagnosis would lower the risk of mortality.

METHODS

This was a prospective study among 926 men with non-metastatic prostate cancer in the Physicians' Health Study who completed a food frequency questionnaire a median of 5 years after diagnosis and were followed for a median of 10 years after the questionnaire. We examined post-diagnostic saturated, monounsaturated, polyunsaturated, and trans fat, as well as animal and vegetable fat, intake in relation to all-cause and prostate cancer-specific mortality. Hazard ratios (HR) and 95 % confidence intervals (CI) were estimated using multivariate Cox proportional hazards regression.

RESULTS

We observed 333 deaths (56 prostate cancer deaths) during follow-up. Men who obtained 5 % more of their daily calories from saturated fat and 5 % less of their daily calories from carbohydrate after diagnosis had a 1.8-fold increased risk of all-cause mortality (HR 1.81; 95 % CI 1.20, 2.74; p value 0.005) and a 2.8-fold increased risk of prostate cancer-specific mortality (HR 2.78; 95 % CI 1.01, 7.64; p value 0.05). Men who obtained 10 % more of their daily calories from vegetable fats and 10 % less of their daily calories from carbohydrates had a 33 % lower risk of all-cause mortality (HR 0.67; 95 % CI 0.47, 0.96; p value 0.03).

CONCLUSIONS

Among men with non-metastatic prostate cancer, saturated fat intake may increase risk of death and vegetable fat intake may lower risk of death.

Urolithin A causes p21 up-regulation in prostate cancer cells

PURPOSE

Walnuts contain several bioactive compounds, including pedunculagin, a polyphenol metabolized by microbiota to form urolithins, namely urolithin A (UA). The aim of this study was to determine gene expression changes in prostate cancer cells after incubation with UA.

METHODS

We performed a genomic analysis to study the effect of UA on LNCaP prostate cells. Cells were incubated with 40 µM UA for 24 h, and RNA was extracted and hybridized to Affymetrix Human Genome U219 array. Microarray results were analyzed using GeneSpring v13 software. Differentially expressed genes (p < 0.05, fold change > 2) were used to perform biological association networks. Cell cycle was analyzed by flow cytometry and apoptosis measured by the rhodamine method and by caspases 3 and 7 activation. Cell viability was determined by MTT assay.

RESULTS

We identified two nodes, FN-1 and CDKN1A, among the differentially expressed genes upon UA treatment. CDKN1A was validated, its mRNA and protein levels were significantly up-regulated, and the promoter activation measured by luciferase. Cell cycle analysis showed an increase in G1-phase, and we also observed an induction of apoptosis and caspases 3 and 7 activation upon UA treatment.

CONCLUSION

Our results indicate a potential role of UA as a chemopreventive agent for prostate cancer.

Overview on the complexity of androgen receptor-targeted therapy for prostate cancer

In the past decades, the field of prostate cancer (PCa) biology has developed exponentially and paralleled with that has been the growing interest in translation of laboratory findings into clinical practice. Based on overwhelming evidence of high impact research findings which support the underlying cause of insufficient drug efficacy in patients progressing on standard androgen deprivation therapy (ADT) is due to persistent activation of the androgen receptor (AR) signaling axis. Therefore, newer agents must be discovered especially because newer ADT such as abiraterone and enzalutamide are becoming ineffective due to rapid development of resistance to these agents. High-throughput technologies are generating massive and highly dimensional genetic variation data that has helped in developing a better understanding of the dynamic repertoire of AR and AR variants. Full length AR protein and its variants modulate a sophisticated regulatory system to orchestrate cellular responses. We partition this multicomponent review into subsections addressing the underlying mechanisms of resistance to recent therapeutics, positive and negative regulators of AR signaling cascade, and how SUMOylation modulates AR induced transcriptional activity. Experimentally verified findings obtained from cell culture and preclinical studies focusing on the potential of natural agents in inhibiting mRNA/protein levels of AR, nuclear accumulation and enhanced nuclear export of AR are also discussed. We also provide spotlight on molecular basis of enzalutamide resistance with an overview of the strategies opted to overcome such resistance. AR variants are comprehensively described and different mechanisms that regulate AR variant expression are also discussed. Reconceptualization of phenotype- and genotype-driven studies have convincingly revealed that drug induced resistance is a major stumbling block in standardization of therapy. Therefore, we summarize succinctly the knowledge of drug resistance especially to ADT and potential avenues to overcome such resistance for improving the treatment outcome of PCa patients.

The ellagic acid-derived gut microbiota metabolite, urolithin A, potentiates the anticancer effects of 5-fluorouracil chemotherapy on human colon cancer cells

The ellagic acid-derived gut microbiota metabolite, urolithin A, at concentrations achievable in the human colorectum, enhances the anticancer effects of 5-FU-chemotherapy on three different colon cancer cells.