Resveratrol modulates cytokine-induced Jak/STAT activation more efficiently than 5-aminosalicylic acid: an in vitro approach. PLoS One. 2014;9:e109048. [PMID: 25271420 PMCID: PMC4182878 DOI: 10.1371/journal.pone.0109048]

Natural products for the treatment of ulcerative colitis: focus on the JAK/STAT pathway

Ulcerative colitis (UC) is an autoimmune disease with an incompletely understood pathogenesis. The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway plays a key role in immune response and inflammation. More and more studies demonstrated that JAK/STAT signaling pathway is associated with the pathogenesis of UC. The JAK/STAT pathway affects UC in multiple ways by regulating intestinal inflammatory response, affecting intestinal mucosal barrier, modulating T cell homeostasis, and regulating macrophages. Encouragingly, natural products are promising candidates for the treatment of UC. Natural products have the advantage of being multi-targeted and rich in therapeutic modalities. This review summarized the research progress of JAK/STAT pathway-mediated UC. Furthermore, the latest studies on natural products targeting the JAK/STAT pathway for the treatment of UC were systematically summarized, including active ingredients such as arbutin, aloe polysaccharide, berberine, matrine, curcumin, Ginsenoside Rh2, and so on. The aim of this paper is to provide new ideas for drug development to regulate JAK/STAT signaling for treating UC.

Resveratrol and p53: How are they involved in CRC plasticity and apoptosis?

BACKGROUND

Colorectal cancer (CRC), which is mainly caused by epigenetic and lifestyle factors, is very often associated with functional plasticity during its development. In addition, the malignant plasticity of CRC cells underscores one of their survival abilities to functionally adapt to specific stresses, including inflammation, that occur during carcinogenesis. This leads to the generation of various subsets of cancer cells with phenotypic diversity and promotes epithelial-mesenchymal transition (EMT), formation of cancer cell stem cells (CSCs) and metabolic reprogramming. This can enhance cancer cell differentiation and facilitate tumorigenic potential, drug resistance and metastasis.

AIM OF REVIEW

The tumor protein p53 acts as one of the central suppressors of carcinogenesis by regulating its target genes, whose proteins are involved in the plasticity of cancer cells, autophagy, cell cycle, apoptosis, DNA repair. The aim of this review is to summarize the latest published research on resveratrol's effect in the prevention of CRC, its regulatory actions, specifically on the p53 pathway, and its treatment options.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Resveratrol, a naturally occurring polyphenol, is a potent inducer of a variety of tumor-controlling. However, the underlying mechanisms linking the p53 signaling pathway to the functional anti-plasticity effect of resveratrol in CRC are still poorly understood. Therefore, this review discusses novel relationships between anti-cellular plasticity/heterogeneity, pro-apoptosis and modulation of tumor protein p53 signaling in CRC oncogenesis, as one of the crucial mechanisms by which resveratrol prevents malignant phenotypic changes leading to cell migration and drug resistance, thus improving the ongoing treatment of CRC.

Resveratrol: biology, metabolism, and detrimental role on the tumor microenvironment of colorectal cancer

A substantial increase in colorectal cancer (CRC)-associated fatalities can be attributed to tumor recurrence and multidrug resistance. Traditional treatment options, including radio- and chemotherapy, also exhibit adverse side effects. Ancient treatment strategies that include phytochemicals like resveratrol are now widely encouraged as an alternative therapeutic option. Resveratrol is the natural polyphenolic stilbene in vegetables and fruits like grapes and apples. It inhibits CRC progression via targeting dysregulated cancer-promoting pathways, including PI3K/Akt/Kras, targeting transcription factors like NF-κB and STAT3, and an immunosuppressive tumor microenvironment. In addition, combination therapies for cancer include resveratrol as an adjuvant to decrease multidrug resistance that develops in CRC cells. The current review discusses the biology of resveratrol and explores different mechanisms of action of resveratrol in inhibiting CRC progression. Further, the detrimental role of resveratrol on the immunosuppressive tumor microenvironment of CRC has been discussed. This review illustrates clinical trials on resveratrol in different cancers, including resveratrol analogs, and their efficiency in promoting CRC inhibition.

Natural Stilbenes: Their Role in Colorectal Cancer Prevention, DNA Methylation, and Therapy

The resistance of colorectal cancer (CRC) to conventional therapeutic modalities, such as radiation therapy and chemotherapy, along with the associated side effects, significantly limits effective anticancer strategies. Numerous epigenetic investigations have unveiled that naturally occurring stilbenes can modify or reverse abnormal epigenetic alterations, particularly aberrant DNA methylation status, offering potential avenues for preventing or treating CRC. By modulating the activity of the DNA methylation machinery components, phytochemicals may influence the various stages of CRC carcinogenesis through multiple molecular mechanisms. Several epigenetic studies, especially preclinical research, have highlighted the effective DNA methylation modulatory effects of stilbenes with minimal adverse effects on organisms, particularly in combination therapies for CRC. However, the available preclinical and clinical data regarding the effects of commonly encountered stilbenes against CRC are currently limited. Therefore, additional epigenetic research is warranted to explore the preventive potential of these phytochemicals in CRC development and to validate their therapeutic application in the prevention and treatment of CRC. This review aims to provide an overview of selected bioactive stilbenes as potential chemopreventive agents for CRC with a focus on their modulatory mechanisms of action, especially in targeting alterations in DNA methylation machinery in CRC.

Resveratrol as sensitizer in colorectal cancer plasticity

Despite tremendous medical treatment successes, colorectal cancer (CRC) remains a leading cause of cancer deaths worldwide. Chemotherapy as monotherapy can lead to significant side effects and chemoresistance that can be linked to several resistance-activating biological processes, including an increase in inflammation, cellular plasticity, multidrug resistance (MDR), inhibition of the sentinel gene p53, and apoptosis. As a consequence, tumor cells can escape the effectiveness of chemotherapeutic agents. This underscores the need for cross-target therapeutic approaches that are not only pharmacologically safe but also modulate multiple potent signaling pathways and sensitize cancer cells to overcome resistance to standard drugs. In recent years, scientists have been searching for natural compounds that can be used as chemosensitizers in addition to conventional medications for the synergistic treatment of CRC. Resveratrol, a natural polyphenolic phytoalexin found in various fruits and vegetables such as peanuts, berries, and red grapes, is one of the most effective natural chemopreventive agents. Abundant in vitro and in vivo studies have shown that resveratrol, in interaction with standard drugs, is an effective chemosensitizer for CRC cells to chemotherapeutic agents and thus prevents drug resistance by modulating multiple pathways, including transcription factors, epithelial-to-mesenchymal transition-plasticity, proliferation, metastasis, angiogenesis, cell cycle, and apoptosis. The ability of resveratrol to modify multiple subcellular pathways that may suppress cancer cell plasticity and reversal of chemoresistance are critical parameters for understanding its anti-cancer effects. In this review, we focus on the chemosensitizing properties of resveratrol in CRC and, thus, its potential importance as an additive to ongoing treatments.

Toll-like receptors in inflammatory bowel disease: A review of the role of phytochemicals

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammation within the gastrointestinal tract with a remarkable impact on patients' quality of life. Toll-like receptors (TLR), as a key contributor of immune system in inflammation, has a critical role in the pathogenesis of IBD and thus, can be a suitable target of therapeutic agents. Medicinal plants have long been considered as a source of bioactive agents for different diseases, including IBD.

PURPOSE

This review discusses current state of the art on the role of plant-derived compounds for the management of IBD with a focus on TLRs.

METHODS

Electronic database including PubMed, Web of Science, and Scopus were searched up to January 2023 and all studies in which anticolitis effects of a phytochemical was assessed via modulation of TLRs were considered.

RESULTS

Different categories of phytochemicals, including flavonoids, lignans, alkaloids, terpenes, saccharides, and saponins have demonstrated modulatory effects on TLR in different animal and cell models of bowel inflammation. Flavonoids were the most studied phytochemicals amongst others. Also, TLR4 was the most important type of TLRs which were modulated by phytochemicals. Other mechanisms such as inhibition of pro-inflammatory cytokines, nuclear factor-κB pathway, nitric oxide synthesis pathway, cyclooxygenase-2, lipid peroxidation, as well as induction of endogenous antioxidant defense mechanisms were also reported for phytochemicals in various IBD models.

CONCLUSION

Taken together, a growing body of pre-clinical evidence support the efficacy of herbal compounds for the treatment of IBD via modulation of TLRs. Future clinical studies are recommended to assess the safety and efficacy of these compounds in human.

Liposomal Epigallocatechin-3-Gallate for the Treatment of Intestinal Dysbiosis in Children with Autism Spectrum Disorder: A Comprehensive Review

Autism Spectrum Disorder (ASD) is characterized by varying degrees of difficulty in social interaction and communication. These deficits are often associated with gastrointestinal symptoms, indicating alterations in both intestinal microbiota composition and metabolic activities. The intestinal microbiota influences the function and development of the nervous system. In individuals with ASD, there is an increase in bacterial genera such as Clostridium, as well as species involved in the synthesis of branched-chain amino acids (BCAA) like Prevotella copri. Conversely, decreased amounts of Akkermansia muciniphila and Bifidobacterium spp. are observed. Epigallocatechin-3-gallate (EGCG) is one of the polyphenols with the greatest beneficial activity on microbial growth, and its consumption is associated with reduced psychological distress. Therefore, the objective of this review is to analyze how EGCG and its metabolites can improve the microbial dysbiosis present in ASD and its impact on the pathology. The analysis reveals that EGCG inhibits the growth of pathogenic bacteria like Clostridium perfringens and Clostridium difficile. Moreover, it increases the abundance of Bifidobacterium spp. and Akkermansia spp. As a result, EGCG demonstrates efficacy in increasing the production of metabolites involved in maintaining epithelial integrity and improving brain function. This identifies EGCG as highly promising for complementary treatment in ASD.

Role of Dietary Polyphenols in the Activity and Expression of Nitric Oxide Synthases: A Review

Nitric oxide (NO) plays several key roles in the functionality of an organism, and it is usually released in numerous organs and tissues. There are mainly three isoforms of the enzyme that produce NO starting from the metabolism of arginine, namely endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and neuronal nitric oxide synthase (nNOS). The expression and activity of these isoforms depends on the activation/deactivation of different signaling pathways at an intracellular level following different physiological and pathological stimuli. Compounds of natural origin such as polyphenols, which are obtainable through diet, have been widely studied in recent years in in vivo and in vitro investigations for their ability to induce or inhibit NO release, depending on the tissue. In this review, we aim to disclose the scientific evidence relating to the activity of the main dietary polyphenols in the modulation of the intracellular pathways involved in the expression and/or functionality of the NOS isoforms.

Inhibition and potential treatment of colorectal cancer by natural compounds via various signaling pathways

Colorectal cancer (CRC) is a common type of malignant digestive tract tumor with a high incidence rate worldwide. Currently, the clinical treatment of CRC predominantly include surgical resection, postoperative chemotherapy, and radiotherapy. However, these treatments contain severe limitations such as drug side effects, the risk of recurrence and drug resistance. Some natural compounds found in plants, fungi, marine animals, and bacteria have been shown to inhibit the occurrence and development of CRC. Although the explicit molecular mechanisms underlying the therapeutic effects of these compounds on CRC are not clear, classical signaling transduction pathways such as NF-kB and Wnt/β-catenin are extensively regulated. In this review, we have summarized the specific mechanisms regulating the inhibition and development of CRC by various types of natural compounds through nine signaling pathways, and explored the potential therapeutic values of these natural compounds in the clinical treatment of CRC.

Role of Energy Metabolism and Mitochondrial Function in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic recurring inflammation of the intestine which can be debilitating for those with intractable disease. However, the etiopathogenesis of inflammatory bowel disorders remains to be solved. The hypothesis that mitochondrial dysfunction is a crucial factor in the disease process is being validated by an increasing number of recent studies. Thus mitochondrial alteration in conjunction with previously identified genetic predisposition, changes in the immune response, altered gut microbiota, and environmental factors (eg, diet, smoking, and lifestyle) are all posited to contribute to IBD. The implicated factors seem to affect mitochondrial function or are influenced by mitochondrial dysfunction, which explains many of the hallmarks of the disease. This review summarizes the results of studies reporting links between mitochondria and IBD that were available on PubMed through March 2021. The aim of this review is to give an overview of the current understanding of the role of mitochondria in the pathogenesis of IBD.

Downregulation of TLR4/MyD88/p38MAPK and JAK/STAT pathway in RAW 264.7 cells by Alpinia galanga reveals its beneficial effects in inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Alpinia galanga, commonly known as greater galangal or raasna, is widely used in Ayurveda against various inflammatory disorders. It is also known as Kulinjan, Aratha, Rasna or Sugandhamula. Some of the Ayurvedic preparations using the rhizome of Alpinia galanga are Rasnadi kashayam, Rasna panchakam, Rasnapthakam, and Rasnarendadi. The aromatic rhizome is the source of the drug greater galangal and it is also used as a spice in South and South East Asia. However, the molecular mechanism of action of A galanga against inflammation remains poorly understood.

AIM OF THE STUDY

To elucidate the anti-inflammatory effect of hydroalcoholic extract of Alpinia galanga rhizome.

STUDY DESIGN/METHOD

The mechanism of the anti-inflammatory effect of hydroalcoholic extract of Alpinia galanga (AGE) was investigated by enzyme-linked immunosorbent assay (ELISA), Western blot, and immunofluorescence in LPS stimulated murine macrophage cell line (RAW 264.7). HPLC analysis was done to elucidate the rich polyphenolic nature of AGE.

RESULTS

The study showed that pre-treatment with AGE downregulated the release of pro-inflammatory mediators (IL-6, TNF-α, NO, and ROS) and stimulated the release of anti-inflammatory mediator IL-10 in LPS stimulated RAW 264.7 cells. The vital enzymes of inflammation (iNOS, COX-2, and MMP-9) were also downregulated by pre-treatment with AGE. AGE targeted the upstream elements of the inflammatory cascade by blocking LPS induced activation of TLR4 and JAK/STAT pathway. The phosphorylation of downstream kinases was significantly affected. The inhibition of nuclear translocation of NFκB further confirmed the specific inhibition of the TLR4 pathway. Particularly AGE inhibited the phosphorylation of JNK, p38, IκBα, and STAT. HPLC analysis of the AGE showed the polyphenol-rich nature of the extract.

CONCLUSIONS

The results from this study provide firm evidence that AGE exerts its anti-inflammatory effect via modulation of TLR4 and JAK/STAT pathway.

Targeting JAK/STAT signaling pathways in treatment of inflammatory bowel disease

Janus kinase/signal transduction and transcriptional activator (JAK/STAT) signaling pathway is a transport hub for cytokine secretion and exerts its effects. The activation of JAK/STAT signaling pathway is essential for the regulation of inflammatory responses. Inappropriate activation or deletion of JAK/STAT signaling pathway is the initiator of the inflammatory response. JAK/STAT signaling pathway has been demonstrated to be involved in the process of innate and adaptive immune response to inflammatory bowel disease (IBD). In this review, we discuss the role of the JAK/STAT signaling pathway in the regulation of different cells in IBD, as well as new findings on the involvement of the JAK/STAT signaling pathway in the regulation of the intestinal immune response. The current status of JAK inhibitors in the treatment of IBD is summarized as well. This review highlights natural remedies that can serve as potential JAK inhibitors. These phytochemicals may be useful in the identification of precursor compounds in the process of designing and developing novel JAK inhibitors.

New tricks of old drugs: Repurposing non-chemo drugs and dietary phytochemicals as adjuvants in anti-tumor therapies

Combination therapy has long been applied to enhance therapeutic effect and deal with the occurrence of multi-drug resistance in cancer treatment. However, the overlapping toxicity of multiple anticancer drugs to healthy tissues and increasing financial burden on patients emerged as major concerns. As promising alternatives to chemo agents, repurposed non-chemo drugs and dietary phytochemicals have been investigated as adjuvants to conventional anti-tumor therapeutics, offering a safe and economic strategy for combination therapy. In this review, we aim to highlight the advances in research about combination therapy using conventional therapeutics and repurposed drugs or phytochemicals for an enhanced anti-tumor efficacy, along with the mechanisms involved in the synergism. Beyond these, we outlined the potential challenges and solutions for clinical translation of the proposed combination therapy, providing a safe and affordable strategy to improve the reach of cancer therapy to low income regions with such new tricks of old drugs.

Interaction of Polyphenols as Antioxidant and Anti-Inflammatory Compounds in Brain-Liver-Gut Axis

Oxidative stress plays an important role in the onset as well as the progression of inflammation. Without proper intervention, acute inflammation could progress to chronic inflammation, resulting in the development of inflammatory diseases. Antioxidants, such as polyphenols, have been known to possess anti-oxidative properties which promote redox homeostasis. This has encouraged research on polyphenols as potential therapeutics for inflammation through anti-oxidative and anti-inflammatory pathways. In this review, the ability of polyphenols to modulate the activation of major pathways of inflammation and oxidative stress, and their potential to regulate the activity of immune cells are examined. In addition, in this review, special emphasis has been placed on the effects of polyphenols on inflammation in the brain–liver–gut axis. The data derived from in vitro cell studies, animal models and human intervention studies are discussed.

Natural Products: Experimental Efficient Agents for Inflammatory Bowel Disease Therapy

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Inflammatory bowel disease (IBD) is a chronic, elusive disorder resulting in relapsing inflammation of intestine with incompletely elucidated etiology, whose two representative forms are ulcerative colitis (UC) and Crohn’s disease (CD). Accumulating researches have revealed that the individual genetic susceptibility, environmental risk elements, intestinal microbial flora, as well as innate and adaptive immune system are implicated in the pathogenesis and development of IBD. Despite remarkable progression of IBD therapy has been achieved by chemical drugs and biological therapies such as aminosalicylates, corticosteroids, antibiotics, anti-tumor necrosis factor (TNF)-α, anti-integrin agents, etc., healing outcome still cannot be obtained, along with inevitable side effects. Consequently, a variety of researches have focused on exploring new therapies, and found that natural products (NPs) isolated from herbs or plants may serve as promising therapeutic agents for IBD through antiinflammatory, anti-oxidant, anti-fibrotic and anti-apoptotic effects, which implicates the modulation on nucleotide- binding domain (NOD) like receptor protein (NLRP) 3 inflammasome, gut microbiota, intestinal microvascular endothelial cells, intestinal epithelia, immune system, etc. In the present review, we will summarize the research development of IBD pathogenesis and current mainstream therapy, as well as the therapeutic potential and intrinsic mechanisms of NPs in IBD.

Kaempferol‑3‑O‑β‑rutinoside suppresses the inflammatory responses in lipopolysaccharide‑stimulated RAW264.7 cells via the NF‑κB and MAPK pathways

Kaempferol‑3‑O‑β‑rutinoside is one of the compounds isolated from tartary buckwheat (Fagopyrum tatricum), and its biological effects have not been studied yet. The present study examined the anti‑inflammatory effects of kaempferol‑3‑O‑β‑rutinoside and explore its regulatory mechanisms in lipopolysaccharide (LPS)‑induced macrophage RAW264.7 cells. Kaempferol‑3‑O‑β‑rutinoside exhibited no cytotoxic effect in RAW 264.7 macrophage and 293 cell lines up to 300 µM. As the concentration of kaempferol‑3‑O‑β‑rutinoside was increased, the activity of nitric oxide was inhibited in LPS‑stimulated RAW264.7 cells. In addition, kaempferol‑3‑O‑β‑rutinoside treatment downregulated the expression of inflammation‑related cytokines tumor necrosis factor‑α and interleukin‑6 in LPS‑stimulated RAW264.7 cells. Furthermore, kaempferol‑3‑O‑β‑rutinoside treatment suppressed inflammatory‑mediated factors, such as inducible nitric oxide synthase and cyclooxyganse‑2. These inflammation‑related proteins are known to be regulated by NF‑κB and mitogen‑activated protein kinase (MAPK) signaling, therefore the effect of kaempferol‑3‑O‑β‑rutinoside on these pathways was investigated. The results demonstrated that kaempferol‑3‑O‑β‑rutinoside decreased the expression of inhibitor of κB (IκB) protein and IκB kinases; as a result, the nuclear translocation and expression of NF‑κB was inhibited in LPS‑stimulated RAW264.7 cells. Furthermore, kaempferol‑3‑O‑β‑rutinoside inhibited the phosphorylation of p38, extracellular signal‑regulated kinase and stress‑activated protein kinase in LPS‑stimulated RAW264.7 cells. Thus, the present data demonstrated that kaempferol‑3‑O‑β‑rutinoside suppressed inflammation‑related gene expression through the NF‑κB and MAPK pathways, and suggested that it may be a useful reagent in pharmacological research.

Polyphenols in the management of brain disorders: Modulation of the microbiota-gut-brain axis

The modulation of the microbiota-gut-brain axis with a view to preventing and treating brain disorders became recently a hot topic for the scientific community. Dietary polyphenols are multifaceted compounds that have demonstrated to be highly advantageous to counteract inflammation, oxidative stress, and neurodegeneration, among other pathological conditions, being useful in the prevention and treatment of several chronic disorders. The potential of these compounds to prevent and treat brain disorders has not been only related to their capacity to reach the brain, depending on their chemical structure, and interact directly with brain cells, but also to their ability to modulate the communication between the brain and the gut, interfering with multiple branches of this axis. Preclinical studies have demonstrated the potential of these food bioactive compounds in brain diseases, namely, neurodevelopmental, such as Down's syndrome and Autism spectrum disorder, neurodegenerative, such as Parkinson's disease and Alzheimer's disease, and psychiatric disorders, such as depression and anxiety. Until now, dietary polyphenols have been recognized as promising nutraceuticals to combat brain disorders. However, the impact of these compounds on the gut-brain interconnection remains poorly elucidated. Also, clinical assays are crucial to further support the beneficial effects of these compounds as demonstrated in preclinical research.

Screening Analysis of Sirtuins Family Expression on Anti-Inflammation of Resveratrol in Endothelial Cells

Background

Resveratrol has been shown to possess beneficial activities including antioxidant, anti-inflammatory, and cardioprotective effects through activating a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase family member sirtuin-1 (SIRT1) protein. The current study was undertaken to investigate the role of sirtuin family members (SIRT1–SIRT7) on the anti-inflammation activities of resveratrol in endothelial cells.

Material/Methods

Primary human umbilical vein endothelial cells (HUVECs) were pretreated with resveratrol before tumor necrosis factor (TNF)-α (10–20 μg/L) stimulation. Cell viability was measured using the Cell Counting Kit-8 method. Total RNA was extracted after different treatments and the NimbleGen Human 12×135K Gene Expression Array was applied to screen and analyze SIRTs expression. Quantitative real-time polymerase chain reaction and western blot were applied to verify the results of the gene expression microarrays. Reactive oxygen species (ROS) production was examined using flow cytometry analysis.

Results

Microarray analysis showed that the expressions of SIRT1, SIRT2, SIRT3, SIRT5, SIRT6, and SIRT7 showed the tendency to increase while SIRT4 showed the tendency to decrease. SIRT1, SIRT2, SIRT5, and SIRT7 gene expression could be upregulated by pretreatment with resveratrol compared with TNF-α alone while there were no obvious differences of SIRT3, SIRT4, and SIRT6 expressions observed in TNF-α alone treated cells and resveratrol-TNF-α co-treated cells. Interestingly, SIRT1, SIRT2, SIRT3, SIRT4, and SIRT5 siRNA could reverse the effect of resveratrol on ROS production; SIRT1 and SIRT5 siRNA could significantly increase CD40 expression inhibited by resveratrol in TNF-α treated cells.

Conclusions

Our results suggest that resveratrol inhibiting oxidative stress production is associated with SIRT1, SIRT2, SIRT3, SIRT4, and SIRT5 pathways; attenuating CD40 expression was only associated with SIRT1 and SIRT5 pathways in TNF-α-induced endothelial cells injury.

Polyphenols as food bioactive compounds in the context of Autism Spectrum Disorders: A critical mini-review

Dietary polyphenols are bioactive compounds with potential in preventing and treating several chronic disorders, mainly due to their ability to modulate key pro-inflammatory and pro-oxidant signalling pathways. Although some studies have expressed concern about their efficacy in vivo, accumulating evidence has suggested that these compounds may achieve large concentrations in the gastrointestinal tract, which may be important in the context of intestinal and of neurological disorders, via modulation of the "gut-brain axis". Autism Spectrum disorders (ASD) are a group of lifelong neurodevelopmental disorders in which many patients suffer from gastrointestinal impairments. Thus, in the scope of these disorders, a growing number of studies have been focused on the microbiota-gut-brain axis. In this mini-review, we present gathered data on gut-to-brain communication in the scope of ASD and we address the advantages of polyphenols in the treatment of these disorders, presenting the more recent preclinical and clinical data on this issue. According to most studies, dietary polyphenols can be a promising strategy for the alleviation of ASD symptoms.

Resveratrol as a Tumor-Suppressive Nutraceutical Modulating Tumor Microenvironment and Malignant Behaviors of Cancer

Tumor-suppressive effects of resveratrol have been shown in various types of cancer. However, regulation of tumor microenvironment by resveratrol is still unclear. Recent findings suggest resveratrol can potentiate its tumor-suppressive effect through modulation of the signaling pathways of cellular components (fibroblasts, macrophages and T cells). Also, studies have shown that resveratrol can suppress malignant phenotypes of cancer cells acquired in response to stresses of the tumor microenvironment, such as hypoxia, oxidative stress and inflammation. We discuss the effects of resveratrol on cancer cells in stress environment of tumors as well as interactions between cancer cells and non-cancer cells in this review.

Targeting STATs in neuroinflammation: The road less traveled!

JAK/STAT transduction pathway is a highly conserved pathway implicated in regulating cellular proliferation, differentiation, survival and apoptosis. Dysregulation of this pathway is involved in the onset of autoimmune, haematological, oncological, metabolic and neurological diseases. Over the last few years, the research of anti-neuroinflammatory agents has gained considerable attention. The ability to diminish the STAT-induced transcription of inflammatory genes is documented for both natural compounds (such as polyphenols) and chemical drugs. Among polyphenols, quercetin and curcumin directly inhibit STAT, while Berberis vulgaris L. and Sophora alopecuroides L extracts act indirectly. Also, the Food and Drug Administration has approved several JAK/STAT inhibitors (direct or indirect) for treating inflammatory diseases, indicating STAT can be considered as a therapeutic target for neuroinflammatory pathologies. Considering the encouraging data obtained so far, clinical trials are warranted to demonstrate the effectiveness and potential use in the clinical practice of STAT inhibitors to treat inflammation-associated neurodegenerative pathologies.

Resveratrol eliminates cancer stem cells of osteosarcoma by STAT3 pathway inhibition

Resveratrol shows potent anti-tumor therapeutic properties in various tumors. However, the exact effect of resveratrol on osteosarcoma cells, especially cancer stem cells, remains unclear. In this study, we examined the effect of resveratrol on osteosarcoma stem cells and explored the underlying molecular mechanisms. Resveratrol inhibited cell viability, self-renewal ability and tumorigenesis of osteosarcoma cells, whereas showed no significant inhibition effects to normal osteoblast cells. Mechanically, resveratrol treatment decreased cytokines synthesis and inhibited JAK2/STAT3 signaling, which was consistent with the decline of cancer stem cells marker, CD133. Exogenous STAT3 activation attenuated the cancer stem cell elimination effects of resveratrol treatment. Our results demonstrated that resveratrol inhibited osteosarcoma cell proliferation and tumorigenesis ability, which was correlated with cytokines inhibition related JAK2/STAT3 signaling blockage. Resveratrol may be a promising therapeutic agent for osteosarcoma management.

Topical Plant Polyphenols Prevent Type I Interferon Signaling in the Skin and Suppress Contact Hypersensitivity

Human keratinocytes were recently shown to respond to anti-EGFR (epidermal growth factor receptor) drugs with activation of an interferon-κ-driven autocrine loop, leading to enhanced expression of innate antiviral effectors and of the pro-inflammatory chemokines CXCL10 (C-X-C motif chemokine 10) and CCL2 (C-C motif ligand 2). Here we showed active type I interferon signaling in the skin lesions of cancer patients undergoing treatment with the anti-EGFR drug cetuximab. Strong nuclear positivity for Interferon Regulatory Factor 1 and phosphorylated Signal Transducer and Activator of Transcription 1, enhanced interferon-κ expression and CXCL10 was associated to the epidermal compartment. Notably, 50 micromolar resveratrol and quercetin fully suppressed the low constitutive levels of type I interferon signaling and prevented its activation by the anti-EGFR cetuximab or gefitinib in cultured keratinocytes. In sensitized mice undergoing DNFB (2,4-dinitro-1-fluorobenzene)-induced contact hypersensitivity, local administration of gefitinib prior to elicitation further amplified hapten-induced type I interferon activation, tissue edema, and infiltration by T cells, whereas resveratrol or quercetin suppressed this inflammatory cascade. Overall, these data suggest that topical application of resveratrol or quercetin could be potentially effective in preventing pathological conditions due to overactivation of type I IFN (interferon)-driven circuits in the skin, including the inflammatory manifestations of anti-EGFR drug-induced skin-targeted toxicity.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Mechanisms of Phytonutrient Modulation of Cyclooxygenase-2 (COX-2) and Inflammation Related to Cancer

The link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways. Cyclooxygenase-2 (COX-2), a key enzyme in fatty acid metabolism, is upregulated during both inflammation and cancer. COX-2 is induced by pro-inflammatory cytokines at the site of inflammation and enhanced COX-2-induced synthesis of prostaglandins stimulates cancer cell proliferation, promotes angiogenesis, inhibits apoptosis, and increases metastatic potential. As a result, COX-2 inhibitors are a subject of intense research interest toward potential clinical applications. Epidemiological studies highlight the potential benefits of diets rich in phytonutrients for cancer prevention. Plants contain numerous phytonutrient secondary metabolites shown to modulate COX-2. Studies have shown that these metabolites, some of which are used in traditional medicine, can reduce inflammation and carcinogenesis. This review describes the molecular mechanisms by which phytonutrients modulate inflammation, including studies of carotenoids, phenolic compounds, and fatty acids targeting various inflammation-related molecules and pathways associated with cancer. Examples of pathways include those of COX-2, mitogen-activated protein kinase kinase kinase, mitogen-activated protein kinase, pro-inflammatory cytokines, and transcription factors like nuclear factor kappa B. Such phytonutrient modulation of COX-2 and inflammation continue to be explored for applications in the prevention and treatment of cancer.

Resveratrol-based cinnamic ester hybrids: synthesis, characterization, and anti-inflammatory activity

Twenty-three novel resveratrol-based cinnamic ester hybrids were designed and synthesized. All the compounds were evaluated for their anti-inflammatory activity using RAW264.7 cells. Among them, compound D15 was found to be the most potent one in inhibiting NO production in LPS-stimulated RAW264.7 cells. The further study indicated that compound D15 could suppress expression of proteins iNOS, COX-2, p-p65, and p-IκB LPS-induced. Immunofluorescence further revealed compound D15 could reduce activation p65 in nuclei. All the results indicated that the anti-inflammatory activity of title compound may partly due to its inhibitory effect on the NF-κB signaling pathway.

Effect of Resveratrol Dry Suspension on Immune Function of Piglets

Resveratrol, a polyphenolic plant antitoxin, has a wide range of pharmacological activities. In this study, we systematically evaluated the effects of resveratrol dry suspension (RDS) on immune function in piglets that were treated with different doses of RDS for 2 weeks. The results showed that the RDS has significant effects on the development, maturation, proliferation, and transformation of T lymphocytes. RDS could regulate humoral immune responses by upregulating the release of IFN-γ and downregulating the release of TNF-α. After piglets were vaccinated against classical swine fever virus and foot-and-mouth disease virus, the antibody titers were significantly increased. RDS treatment showed an excellent resistance to enhance T-SOD activity. Values of blood routine and blood biochemistry showed no toxicity. These results suggested that RDS could be considered as an adjuvant to enhance immune responses to vaccines, as well as dietary additives for animals to enhance humoral and cellular immunity.

Resveratrol and inflammatory bowel disease: the evidence so far

Despite the fact that inflammatory bowel disease (IBD) has still no recognised therapy, treatments which have proven at least mildly successful in improving IBD symptoms include anti-inflammatory drugs and monoclonal antibodies targeting pro-inflammatory cytokines. Resveratrol, a natural (poly)phenol found in grapes, red wine, grape juice and several species of berries, has been shown to prevent and ameliorate intestinal inflammation. Here, we discuss the role of resveratrol in the improvement of inflammatory disorders involving the intestinal mucosa. The present review covers three specific aspects of resveratrol in the framework of inflammation: (i) its content in food; (ii) its intestinal absorption and metabolism; and (iii) its anti-inflammatory effects in the intestinal mucosa in vitro and in the very few in vivo studies present to date. Actually, if several studies have shown that resveratrol may down-regulate mediators of intestinal immunity in rodent models, only two groups have performed intervention studies in human subjects using resveratrol as an agent to improve IBD conditions. The effects of resveratrol should be further investigated by conducting well-designed clinical trials, also taking into account different formulations for the delivery of the bioactive compound.

Modulating effect of inositol hexaphosphate on arachidonic acid-dependent pathways in colon cancer cells

Cyclooxygenase (COX) and lipoxygenase (LOX) are key enzymes of arachidonic acid metabolism. Their products, prostaglandins and leukotrienes, are involved in the pathogenesis of inflammatory bowel diseases and colorectal cancer. The aim of the study was to examine the influence of inositol hexaphosphate (IP6), a naturally occurring phytochemical, on the expression of genes encoding COX and LOX isoforms and synthesis of their products (PGE₂ and LTB₄) in colon cancer cell line Caco-2 stimulated with pro-inflammatory agents (IL-1β/TNFα). Real-time RT-qPCR was used to validate mRNAs level of examined genes. The concentrations of COX-2 and 5-LOX proteins as well as PGE2 and LTB4 were determined by the ELISA method. Based on these studies it may be concluded that IP6 may limit inflammatory events in the colonic epithelium and prevent colon carcinomas by modulating the expression of genes encoding COX and LOX isoforms at both mRNA and protein levels as well as by affecting the synthesis and secretion of prostaglandins and leukotrienes.

Comparison of anti-inflammatory activities of an anthocyanin-rich fraction from Portuguese blueberries (Vaccinium corymbosum L.) and 5-aminosalicylic acid in a TNBS-induced colitis rat model

Despite the actual therapeutic approaches for inflammatory bowel disease (IBD), efficient and secure alternative options remain a research focus. In this context, anthocyanins seem promising natural anti-inflammatory agents, but their action mechanisms and efficacy as compared with established drugs still require more clarification. The main aim of this study was to compare the anti-inflammatory action of a chemically characterized anthocyanin-rich fraction (ARF), obtained from Portuguese blueberries (Vaccinium corymbosum L.), with that of 5-aminosalicylic acid (5-ASA), a first-line drug in IBD, in a 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis rat model. Such fraction showed a high content and great molecular diversity of anthocyanins, with malvidin-3-galactoside and petunidin-3-arabinoside in the highest concentrations. After daily administration by intragastric infusion for 8 days, ARF, at a molar anthocyanin concentration about 30 times lower than 5-ASA, showed a higher effectiveness in counteracting the intestinal inflammation, as assessed by i) body weight variation and colon damage score, ii) reduction in leukocyte infiltration, iii) increase in antioxidant defenses and iv) by downregulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in colon tissue homogenates. The strong inhibition of COX-2 expression seems to be a crucial anti-inflammatory mechanism common to both ARF and 5-ASA, but the additional higher abilities of anthocyanins to downregulate iNOS and to decrease leukocytes infiltration and to increase antioxidant defenses in colon may account for the much higher anti-inflammatory action of anthocyanins. These data may contribute to the development of a promising natural approach in IBD management.

Resveratrol mitigates lipopolysaccharide-mediated acute inflammation in rats by inhibiting the TLR4/NF-κBp65/MAPKs signaling cascade

Resveratrol (RSV) is a natural compound exhibiting anti-inflammatory effect, but the anti-inflammatory mechanism has not been fully understood. This study is aimed to evaluate the anti-inflammatory activity and mechanism of RSV in lipopolysaccharides-induced rats’ model. The visceral wet/dry weight ratios and the changes of hematologic and biochemical indices indicated that LPS- stimulation mainly caused damages to liver and lung, while pretreatment with RSV could alleviate the lesions. The cytokine assays showed that RSV could markedly decrease the production of proinflammatory mediators and cytokines (IL-1, IL-1β, IL-6, NO, iNOS and COX-2), and increase the expression of anti-inflammatory mediator (IL-10). RSV could inhibit TLR4 signaling pathway by down-regulating the mRNA levels of MyD88 and TRAF6, and suppressing the TLR4 protein. RSV could inhibit the signaling cascades of NF-κBp65 and MAPKs through down-regulating the mRNA levels of IκBα, p38MAPK, JNK, ERK1, ERK2 and ERK5 in liver and lung, and suppressing the dynamic changes of proteins and phosphorylated proteins including IκBα, NF-κBp65, p38MAPK, JNK, ERK1/2 and ERK5 from tissue’s cytoplasm to nucleus. In conclusion, RSV possessed a therapeutic effect on LPS-induced inflammation in rats and the mechanism mainly attributed to suppressing the signaling cascades of NF-κBp65 and MAPKs by inhibiting the TLR4 signaling pathway.

Anti-inflammatory protection afforded by cyanidin-3-glucoside and resveratrol in human intestinal cells via Nrf2 and PPAR-γ: Comparison with 5-aminosalicylic acid

This study investigated the involvement of nuclear factor erythroid 2 (Nrf2) and peroxisome proliferator-activated receptor-gamma (PPAR-γ) pathways in the protection afforded by two polyphenols abundant in diet, cyanidin-3-glucoside and resveratrol, against cytokine-induced inflammation and oxidative insult in HT-29 intestinal cells, in comparison with the drug 5-aminosalicylic acid (5-ASA). Our data show for the first time that in cytokine-challenged cells, cyanidin-3-glucoside and resveratrol induced Nrf2 activation, increased hemoxygenase-1 and glutamate cysteine ligase mRNA expression, enhanced reduced glutathione to oxidized glutathione ratio and inhibited reactive species production, at much lower concentrations than 5-ASA. Unlike cyanidin-3-glucoside, resveratrol and 5-ASA also increased nuclear levels of PPAR-γ in cytokine-stimulated cells. In conclusion, both polyphenols might be interesting as nutraceuticals, giving complementary benefits to conventional drugs against intestinal inflammation, typically present in patients with inflammatory bowel disease.

Tuning constitutive and pathological inflammation in the gut via the interaction of dietary nitrate and polyphenols with host microbiome

Chronic inflammation is currently recognized as a critical process in modern-era epidemics such as diabetes, obesity and neurodegeneration. However, little attention is paid to the constitutive inflammatory pathways that operate in the gut and that are mandatory for local welfare and the prevention of such multi-organic diseases. Hence, the digestive system, while posing as a barrier between the external environment and the host, is crucial for the balance between constitutive and pathological inflammatory events. Gut microbiome, a recently discovered organ, is now known to govern the interaction between exogenous agents and the host with ensued impact on local and systemic homeostasis. Whereas gut microbiota may be modulated by a myriad of factors, diet constitutes one of its major determinants. Thus, dietary compounds that influence microbial flora may thereby impact on inflammatory pathways. One such example is the redox environment in the gut lumen which is highly dependent on the local generation of nitric oxide along the nitrate-nitrite-nitric oxide pathway and that is further enhanced by simultaneous consumption of polyphenols. In this paper, different pathways encompassing the interaction of dietary nitrate and polyphenols with gut microbiota will be presented and discussed in connection with local and systemic inflammatory events. Furthermore, it will be discussed how these interactive cycles (nitrate-polyphenols-microbiome) may pose as novel strategies to tackle inflammatory diseases.

Targeting arachidonic acid pathway by natural products for cancer prevention and therapy

Arachidonic acid (AA) pathway, a metabolic process, plays a key role in carcinogenesis. Hence, AA pathway metabolic enzymes phospholipase A₂s (PLA₂s), cyclooxygenases (COXs) and lipoxygenases (LOXs) and their metabolic products, such as prostaglandins and leukotrienes, have been considered novel preventive and therapeutic targets in cancer. Bioactive natural products are a good source for development of novel cancer preventive and therapeutic drugs, which have been widely used in clinical practice due to their safety profiles. AA pathway inhibitory natural products have been developed as chemopreventive and therapeutic agents against several cancers. Curcumin, resveratrol, apigenin, anthocyans, berberine, ellagic acid, eugenol, fisetin, ursolic acid, [6]-gingerol, guggulsteone, lycopene and genistein are well known cancer chemopreventive agents which act by targeting multiple pathways, including COX-2. Nordihydroguaiaretic acid and baicalein can be chemopreventive molecules against various cancers by inhibiting LOXs. Several PLA₂s inhibitory natural products have been identified with chemopreventive and therapeutic potentials against various cancers. In this review, we critically discuss the possible utility of natural products as preventive and therapeutic agents against various oncologic diseases, including prostate, pancreatic, lung, skin, gastric, oral, blood, head and neck, colorectal, liver, cervical and breast cancers, by targeting AA pathway. Further, the current status of clinical studies evaluating AA pathway inhibitory natural products in cancer is reviewed. In addition, various emerging issues, including bioavailability, toxicity and explorability of combination therapy, for the development of AA pathway inhibitory natural products as chemopreventive and therapeutic agents against human malignancy are also discussed.

Bioactivity of Polyphenols: Preventive and Adjuvant Strategies toward Reducing Inflammatory Bowel Diseases-Promises, Perspectives, and Pitfalls

Inflammatory bowel diseases (IBDs) are characterized by autoimmune and inflammation-related complications of the large intestine (ulcerative colitis) and additional parts of the digestive tract (Crohn's disease). Complications include pain, diarrhoea, chronic inflammation, and cancer. IBD prevalence has increased during the past decades, especially in Westernized countries, being as high as 1%. As prognosis is poor and medication often ineffective or causing side effects, additional preventive/adjuvant strategies are sought. A possible approach is via diets rich in protective constituents. Polyphenols, the most abundant phytochemicals, have been associated with anti-inflammatory, antioxidant, immunomodulatory, and apoptotic properties. Locally reducing oxidative stress, they can further act on cellular targets, altering gene expression related to inflammation, including NF-κB, Nrf-2, Jak/STAT, and MAPKs, suppressing downstream cytokine formation (e.g., IL-8, IL-1β, and TNF-α), and boosting the bodies' own antioxidant status (HO-1, SOD, and GPx). Moreover, they may promote, as prebiotics, healthy microbiota (e.g., Bifidobacteria, Akkermansia), short-chain fatty acid formation, and reduced gut permeability/improved tight junction stability. However, potential adverse effects such as acting as prooxidants, or perturbations of efflux transporters and phase I/II metabolizing enzymes, with increased uptake of undesired xenobiotics, should also be considered. In this review, we summarize current knowledge around preventive and arbitrary actions of polyphenols targeting IBD.

Metabolic and Microbial Modulation of the Large Intestine Ecosystem by Non-Absorbed Diet Phenolic Compounds: A Review

Phenolic compounds represent a diverse group of phytochemicals whose intake is associated with a wide spectrum of health benefits. As consequence of their low bioavailability, most of them reach the large intestine where, mediated by the action of local microbiota, a series of related microbial metabolites are accumulated. In the present review, gut microbial transformations of non-absorbed phenolic compounds are summarized. Several studies have reached a general consensus that unbalanced diets are associated with undesirable changes in gut metabolism that could be detrimental to intestinal health. In terms of explaining the possible effects of non-absorbed phenolic compounds, we have also gathered information regarded their influence on the local metabolism. For this purpose, a number of issues are discussed. Firstly, we consider the possible implications of phenolic compounds in the metabolism of colonic products, such as short chain fatty acids (SCFA), sterols (cholesterol and bile acids), and microbial products of non-absorbed proteins. Due to their being recognized as affective antioxidant and anti-inflammatory agents, the ability of phenolic compounds to counteract or suppress pro-oxidant and/or pro-inflammatory responses, triggered by bowel diseases, is also presented. The modulation of gut microbiota through dietetic maneuvers including phenolic compounds is also commented on. Although the available data seems to assume positive effects in terms of gut health protection, it is still insufficient for solid conclusions to be extracted, basically due to the lack of human trials to confirm the results obtained by the in vitro and animal studies. We consider that more emphasis should be focused on the study of phenolic compounds, particularly in their microbial metabolites, and their power to influence different aspects of gut health.

Role of phytochemicals in colorectal cancer prevention

Although the incidence of colorectal cancer (CRC) has been declining in recent decades, it remains a major public health issue as a leading cause of cancer mortality and morbidity worldwide. Prevention is one milestone for this disease. Extensive study has demonstrated that a diet containing fruits, vegetables, and spices has the potential to prevent CRC. The specific constituents in the dietary foods which are responsible for preventing CRC and the possible mechanisms have also been investigated extensively. Various phytochemicals have been identified in fruits, vegetables, and spices which exhibit chemopreventive potential. In this review article, chemopreventive effects of phytochemicals including curcumin, polysaccharides (apple polysaccharides and mushroom glucans), saponins (Paris saponins, ginsenosides and soy saponins), resveratrol, and quercetin on CRC and the mechanisms are discussed. This review proposes the need for more clinical evidence for the effects of phytochemicals against CRC in large trials. The conclusion of the review is that these phytochemicals might be therapeutic candidates in the campaign against CRC.

Effects of sulfamethoxazole-trimethoprim associated to resveratrol on its free form and complexed with 2-hydroxypropyl-β-cyclodextrin on cytokines levels of mice infected by Toxoplasma gondii

The aim of this study was to investigate the effects of resveratrol on its free form and complexed with 2-hydroxypropyl-β-cyclodextrin (HPβCD) when associated with sulfamethoxazole-trimethoprim (ST) on cytokines levels of mice (n = 60) experimentally infected by Toxoplasma gondii. Groups A and E were used as controls (untreated): negative and positive, respectively. The onset of treatment started 20 days post-infection (PI), and it lasted for 10 consecutive days. ST was administered orally in doses of 0.5 mg kg(-1) for groups B and F, while 100 mg kg(-1) was the dose for resveratrol in its free form (groups C - G), inclusion complex (groups D and H), and on free and inclusion complex together (groups I - J). On day 31 PI, blood samples were collected in order to evaluate the cytokine profile. The mice that received drug combination (I and J) showed a significant (P < 0.05) reduction in the number of cysts in the brain compared to other infected groups (E - H). The results showed that mice from the Group E had increased (P < 0.001) levels of pro-inflammatory cytokines, while IL-10 levels were reduced when compared to the Group A. Additionally, there were increased levels of IL-4 and IFN-γ in animals of groups C and D, respectively (P < 0.05). Animals of the Group B showed reduced levels of IL-1, IL-4, IL-6, TNF-α, and IFN-γ (P < 0.05). Mice infected and treated (groups F - J) showed increased levels of pro-inflammatory cytokines along with a reduction of IL-10. Treatment with the combination of drugs (the Group J) led to a protective effect, i.e. reduction in pro-inflammatory cytokines. Therefore, resveratrol associated with ST was able to modulate seric cytokine profile and moderate the tissue inflammatory process caused by T. gondii infection, as well as to reduce parasite multiplication.

In vitro and in vivo antitumoral effects of combinations of polyphenols, or polyphenols and anticancer drugs: perspectives on cancer treatment

Carcinogenesis is a multistep process triggered by genetic alterations that activate different signal transduction pathways and cause the progressive transformation of a normal cell into a cancer cell. Polyphenols, compounds ubiquitously expressed in plants, have anti-inflammatory, antimicrobial, antiviral, anticancer, and immunomodulatory properties, all of which are beneficial to human health. Due to their ability to modulate the activity of multiple targets involved in carcinogenesis through direct interaction or modulation of gene expression, polyphenols can be employed to inhibit the growth of cancer cells. However, the main problem related to the use of polyphenols as anticancer agents is their poor bioavailability, which might hinder the in vivo effects of the single compound. In fact, polyphenols have a poor absorption and biodistribution, but also a fast metabolism and excretion in the human body. The poor bioavailability of a polyphenol will affect the effective dose delivered to cancer cells. One way to counteract this drawback could be combination treatment with different polyphenols or with polyphenols and other anti-cancer drugs, which can lead to more effective antitumor effects than treatment using only one of the compounds. This report reviews current knowledge on the anticancer effects of combinations of polyphenols or polyphenols and anticancer drugs, with a focus on their ability to modulate multiple signaling transduction pathways involved in cancer.