Comparison of the effects of the chemopreventive agent resveratrol and its synthetic analog trans 3,4,5,4'-tetramethoxystilbene (DMU-212) on adenoma development in the Apc(Min+) mouse and cyclooxygenase-2 in human-derived colon cancer cells

Catalytic divergence of O-methyltransferases shapes the chemo-diversity of polymethoxylated bibenzyls in Dendrobium catenatum

Erianin, crepidatin, and chrysotobibenzyl are typical medicinal polymethoxylated bibenzyls (PMBs) that are commercially produced in Dendrobium species. PMBs' chemo-diversity is mediated by the manifold combinations of O-methylation and hydroxylation in a definite order, which remains unsolved. To unequivocally elucidate the methylation mechanism of PMBs, 15 possible intermediates in the biosynthetic pathway of PMBs were chemically synthesized. DcOMT1-5 were highly expressed in tissues where PMBs were biosynthesized, and their expression patterns were well-correlated with the accumulation profiles of PMBs. Moreover, cell-free orthogonal tests based on the synthesized intermediates further confirmed that DcOMT1-5 exhibited distinct substrate preferences and displayed hydroxyl-group regiospecificity during the sequential methylation process. The stepwise methylation of PMBs was discovered from SAM to dihydro-piceatannol (P) in the following order: P → 3-MeP → 4-OH-3-MeP → 4-OH-3,5-diMeP → 3,3'(4'),5-triMeP → 3,4,4',5-tetraMeP (erianin) or 3,3',4,5-tetraMeP (crepidatin) → 3,3',4,4',5-pentaMeP (chrysotobibenzyl). Furthermore, the regioselectivities of DcOMTs were investigated by ligand docking analyses which corresponded precisely with the catalytic activities. In summary, the findings shed light on the sequential catalytic mechanisms of PMB biosynthesis and provide a comprehensive PMB biosynthetic network in D. catenatum. The knowledge gained from this study may also contribute to the development of plant-based medicinal applications and the production of high-value PMBs.

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.

Catalytic acceptorless dehydrogenative borylation of styrenes enabled by a molecularly defined manganese complex

In this study, we employed a 3d metal complex as a catalyst to synthesize alkenyl boronate esters through the dehydrogenative coupling of styrenes and pinacolborane. The process generates hydrogen gas as the sole byproduct without requiring an acceptor, rendering it environmentally friendly and atom-efficient. This methodology demonstrated exceptional selectivity for dehydrogenative borylation over direct hydroboration. Additionally, it exhibited a preference for borylating aromatic alkenes over aliphatic ones. Notably, derivatives of natural products and bioactive molecules successfully underwent diversification using this approach. The alkenyl boronate esters served as precursors for the synthesis of various pharmaceuticals and potential anticancer agents. Our research involved comprehensive experimental and computational studies to elucidate the reaction pathway, highlighting the B-H bond cleavage as the rate-determining step. The catalyst's success was attributed to the hemilability and metal-ligand bifunctionality of the ligand backbone.

CYP1-Activation and Anticancer Properties of Synthetic Methoxylated Resveratrol Analogues

Naturally occurring stilbenoids, such as the (E)-stilbenoid resveratrol and the (Z)-stilbenoid combretastatin A4, have been considered as promising lead compounds for the development of anticancer drugs. The antitumour properties of stilbenoids are known to be modulated by cytochrome P450 enzymes CYP1A1 and CYP1B1, which contribute to extrahepatic phase I xenobiotic and drug metabolism. Thirty-four methyl ether analogues of resveratrol were synthesised, and their anticancer properties were assessed, using the MTT cell proliferation assay on a panel of human breast cell lines. Breast tumour cell lines that express CYP1 were significantly more strongly affected by the resveratrol analogues than the cell lines that did not have CYP1 activity. Metabolism studies using isolated CYP1 enzymes provided further evidence that (E)-stilbenoids can be substrates for these enzymes. Structures of metabolic products were confirmed by comparison with synthetic standards and LC-MS co-elution studies. The most promising stilbenoid was (E)-4,3',4',5'-tetramethoxystilbene (DMU212). The compound itself showed low to moderate cytotoxicity, but upon CYP1-catalysed dealkylation, some highly cytotoxic metabolites were formed. Thus, DMU212 selectively affects proliferation of cells that express CYP1 enzymes.

Steroidogenic activity of liposomal methylated resveratrol analog 3,4,5,4'-tetramethoxystilbene (DMU-212) in human luteinized granulosa cells in a primary three-dimensional in vitro model

PURPOSE

Steroid hormone secretion is one of the key functions of granulosa cells (GCs). Resveratrol is a natural polyphenol, known for its beneficial health effects, such as improving reproductive health. However, its application is limited due to poor bioavailability. The methoxy derivative of resveratrol (DMU-212) was demonstrated to be more lipophilic, and therefore of greater bioavailability. However, since the addition of methoxy groups to the stilbene scaffold was found to make the molecule insoluble in water, DMU-212 was loaded into liposomes. This study aimed to evaluate how the liposomal formulation of DMU-212 (lipDMU-212) alters estradiol and progesterone secretion of human ovarian GCs in a primary three-dimensional cell culture model.

METHODS

DMU-212-loaded liposomes were prepared by thin film hydration followed by extrusion. Cell viability was measured after exposure of GCs spheroids to the liposomal formulation of DMU-212 using CellTiter-Glo® 3D Cell Viability Assay. The secretion of estradiol and progesterone was determined using commercial ELISA kits. RT-qPCR was conducted to analyze the expression of steroidogenesis-related genes. Finally, the western blot technique was used to analyze the effect of lipDMU-212 and FSH treatments on CYP11A1 and HSD3B1 protein levels.

RESULTS

lipDMU-212 was found to significantly increase estradiol and progesterone secretion in a dose-dependent manner by enhancing the expression of CYP11A1, HSD3B1, StAR, CYP17A1, CYP19A1, and HSD17B1 genes. We have also shown that lipDMU-212, used alone and in combination with FSH, significantly increased the expression of the HSD3B1 and CYP11A1 proteins in GCs. Furthermore, our study suggests that lipDMU-212 increases FSH activity.

CONCLUSIONS

This is the first study to describe the steroidogenic activity of liposomal formulation of DMU-212, possibly through increasing the StAR and CYP19A1 expression. These findings suggest that lipDMU-212 might have a beneficial effect in the treatment of disorders related to estrogen deficiency and hyperandrogenism, such as PCOS.

In Vivo Metabolite Profiling of DMU-212 in ApcMin/+ Mice Using UHPLC-Q/Orbitrap/LTQ MS

3,4,5,4'-Trans-tetramethoxystilbene (Synonyms: DMU-212) is a resveratrol analogue with stronger antiproliferative activity and more bioavailability. However, the metabolite characterization of this component remains insufficient. An efficient strategy was proposed for the comprehensive in vivo metabolite profiling of DMU-212 after oral administration in ApcMin/+ mice based on the effectiveness of the medicine. Ultra-high performance liquid chromatography-quadrupole/orbitrap/linear ion trap mass spectrometry (UHPLC-Q/Orbitrap/LTQ MS) in the AcquireXTM intelligent data acquisition mode, combining the exact mass and structural information, was established for the profiling and identification of the metabolites of DMU-212 in vivo, and the possible metabolic pathways were subsequently proposed after the oral dose of 240mg/kg for 3 weeks in the colorectal adenoma (CRA) spontaneous model ApcMin/+ mice. A total of 63 metabolites of DMU-212 were tentatively identified, including 48, 48, 34 and 28 metabolites in the ApcMin/+ mice's intestinal contents, liver, serum, and colorectal tissues, respectively. The metabolic pathways, including demethylation, oxidation, desaturation, methylation, acetylation, glucuronide and cysteine conjugation were involved in the metabolism. Additionally, further verification of the representative active metabolites was employed using molecular docking analysis. This study provides important information for the further investigation of the active constituents of DMU-212 and its action mechanisms for CRA prevention.

Phytochemicals in Cancer Treatment and Cancer Prevention-Review on Epidemiological Data and Clinical Trials

Phytochemicals are a non-nutritive substances that are present in plants and contribute significantly to their flavor and color. These biologically active compounds are classified into five major groups, namely phenolics, carotenoids, organosulfur compounds, nitrogen-containing compounds, and alkaloids, and are known for their potential health benefits in the prevention of various diseases, including cancer. The purpose of this review article is to explore the potential therapeutic benefits of the dietary phytochemicals, such as flavonoids, phenolic acids, phytosterols, carotenoids, and stilbenes, in cancer treatment and prevention based on the epidemiological studies and clinical trials. Although the majority of epidemiological studies report a significant advantage of the heightened phytochemical consumption and increased serum levels of these compounds, linking increased exposure with a lower cancer risk across most cancer types, these effects could not be replicated in the most available clinical trials. In fact, many of these trials were withdrawn early due to a lack of evidence and/or risk of harm. Despite the strong anticancer effect of phytochemicals, as well as their proven efficacy in multiple epidemiological studies, there is still a great need for human studies and clinical trials, with great caution regarding the safety measures. This review article provides an overview of the epidemiological and clinical evidence supporting the potential chemopreventive and anticancer properties of phytochemicals, with a focus on the need for further research in this area.

Applications of resveratrol in the treatment of gastrointestinal cancer

Natural product compounds have lately attracted interest in the scientific community as a possible treatment for gastrointestinal (GI) cancer, due to their anti-inflammatory and anticancer properties. There are many preclinical, clinical, and epidemiological studies, suggesting that the consumption of polyphenol compounds, which are abundant in vegetables, grains, fruits, and pulses, may help to prevent various illnesses and disorders from developing, including several GI cancers. The development of GI malignancies follows a well-known path, in which normal gastrointestinal cells acquire abnormalities in their genetic composition, causing the cells to continuously proliferate, and metastasize to other sites, especially the brain and liver. Natural compounds with the ability to affect oncogenic pathways might be possible treatments for GI malignancies, and could easily be tested in clinical trials. Resveratrol is a non-flavonoid polyphenol and a natural stilbene, acting as a phytoestrogen with anti-cancer, cardioprotective, anti-oxidant, and anti-inflammatory properties. Resveratrol has been shown to overcome resistance mechanisms in cancer cells, and when combined with conventional anticancer drugs, could sensitize cancer cells to chemotherapy. Several new resveratrol analogs and nanostructured delivery vehicles with improved anti-GI cancer efficacy, absorption, and pharmacokinetic profiles have already been developed. This present review focuses on the in vitro and in vivo effects of resveratrol on GI cancers, as well as the underlying molecular mechanisms of action.

SIRT1 inhibition-induced senescence as a strategy to prevent prostate cancer progression

Emerging evidence suggests an important role for SIRT1, a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase in cancer development, progression and therapeutic resistance; making it a viable therapeutic target. Here, we examined the impact of resveratrol-mediated pharmacological activation of SIRT1 on the progression of HGPIN lesions (using the Pten^-/- mouse model) and on prostate tumor development (using an orthotopic model of prostate cancer cells stably silenced for SIRT1). We show that precise SIRT1 modulation could benefit both cancer prevention and treatment. Positive effect of SIRT1 activation can prevent Pten deletion-driven development of HGPIN lesions in mice if resveratrol is administered early (pre-cancer stage) with little to no benefit after the establishment of HGPIN lesions or tumor cell implantation. Mechanistically, our results show that under androgen deprivation conditions, SIRT1 inhibition induces senescence as evidenced by decreased gene signature associated with negative regulators of senescence and increased senescence-associated β-galactosidase activity. Furthermore, pharmacological inhibition of SIRT1 potentiated growth inhibitory effects of clinical androgen receptor blockade agents and radiation. Taken together, our findings provide an explanation for the discrepancy regarding the role of SIRT1 in prostate tumorigenesis. Our results reveal that the bifurcated roles for SIRT1 may occur in stage and context-dependent fashion by functioning in an antitumor role in prevention of early-stage prostate lesion development while promoting tumor development and disease progression post-lesion development. Clinically, these data highlight the importance of precise SIRT1 modulation to provide benefits for cancer prevention and treatment including sensitization to conventional therapeutic approaches.

Redox modulation of vitagenes via plant polyphenols and vitamin D: Novel insights for chemoprevention and therapeutic interventions based on organoid technology

Polyphenols are chemopreventive through the induction of nuclear factor erythroid 2 related factor 2 (Nrf2)-mediated proteins and anti-inflammatory pathways. These pathways, encoding cytoprotective vitagenes, include heat shock proteins, such as heat shock protein 70 (Hsp70) and heme oxygenase-1 (HO-1), as well as glutathione redox system to protect against cancer initiation and progression. Phytochemicals exhibit biphasic dose responses on cancer cells, activating at low dose, signaling pathways resulting in upregulation of vitagenes, as in the case of the Nrf2 pathway upregulated by hydroxytyrosol (HT) or curcumin and NAD/NADH-sirtuin-1 activated by resveratrol. Here, the importance of vitagenes in redox stress response and autophagy mechanisms, as well as the potential use of dietary antioxidants in the prevention and treatment of multiple types of cancer are discussed. We also discuss the possible relationship between SARS-CoV-2, inflammation and cancer, exploiting innovative therapeutic approaches with HT-rich aqueous olive pulp extract (Hidrox®), a natural polyphenolic formulation, as well as the rationale of Vitamin D supplementation. Finally, we describe innovative approaches with organoids technology to study human carcinogenesis in preclinical models from basic cancer research to clinical practice, suggesting patient-derived organoids as an innovative tool to test drug toxicity and drive personalized therapy.

Changes in Serum, Red Blood Cell, and Colonic Fatty Acids in a Personalized Omega-3 Fatty Acid Supplementation Trial

This study evaluated changes in fatty acids from sera, red blood cells, and colonic biopsies from a phase Ib clinical trial of personalized ω-3 fatty acid dosing in 47 healthy volunteers. The trial aimed to reduce colonic prostaglandin E₂ (PGE₂), a pro-inflammatory product of arachidonic acid (AA) oxidation. The personalized doses ranged 2-10 grams/day (54% eicosapentaenoic acid, EPA, 24% other ω-3 fatty acids). In colon, increases in ω-3 highly unsaturated fatty acids (HUFA) and EPA:AA ratios each were correlated with decreases in PGE₂. Changes in either colonic EPA:AA ratios or ω-3 HUFA were significantly correlated with changes in the same fatty acid measures in red blood cells or serum. The only blood-based measure significantly correlated with changes in colonic PGE₂ was change in red blood cell ω-3 HUFA (ρ = -0.39), and the increase in red blood cell ω-3 HUFA was significantly greater in participants who had at least a median reduction in colonic PGE₂ vs. those who did not. In summary, fatty acid changes in blood did reflect fatty acid changes in the colon, but additional factors will be needed for optimizing dosing models that seek to predict the anti-inflammatory effects of ω-3 fatty acids on the colon.

An Adaptive Bayesian Design for Personalized Dosing in a Cancer Prevention Trial

INTRODUCTION

In biomarker-driven clinical trials, translational strategies typically involve moving findings from animal experiments to human trials. Typically, the translation is static, using a fixed model derived from animal experiments for the duration of the trial. Bayesian designs, capable of incorporating information external to the experiment, provide a dynamic translational strategy. This article demonstrates an example of such a dynamic Bayesian strategy in a clinical trial.

METHODS

This study explored the effect of a personalized dose of fish oil for reducing prostaglandin E₂, an inflammatory marker linked to colorectal cancer. A Bayesian design was implemented for the dose-finding algorithm that adaptively updated a dose-response model derived from a previously completed animal study during the clinical trial. In the initial stages of the trial, the dose-response model parameters were estimated from the rodent data. The model was updated following a Bayesian algorithm after data on every 10‒15 subjects were obtained until the model stabilized. Subjects were enrolled in the study between 2013 and 2015, and the data analysis was carried out in 2016.

RESULTS

The 3 dosing models were used for groups of 16, 15, and 15 subjects. The mean target dose significantly decreased from 6.63 g/day (Model 1) to 4.06 g/day (Model 3) (p=0.001). Compared with the static strategy of dosing with a single model, the dynamic modeling reduced the dose significantly by about 1.38 g/day on average.

CONCLUSIONS

A Bayesian design was effective in adaptively revising the dosing algorithm, resulting in a lower pill burden.

TRIAL REGISTRATION

This study is registered at www.clinicaltrials.gov NCT01860352.

Mechanisms of resveratrol in the prevention and treatment of gastrointestinal cancer

Gastrointestinal (GI) cancer is one of the leading causes of cancer-related deaths worldwide. According to the Global Cancer Statistics, colorectal cancer is the second leading cause of cancer-related mortality, closely followed by gastric cancer (GC). Environmental, dietary, and lifestyle factors including cigarette smoking, alcohol intake, and genetics are the most important risk factors for GI cancer. Furthermore, infections caused by Helicobacter pylori are a major cause of GC initiation. Despite improvements in conventional therapies, including surgery, chemotherapy, and radiotherapy, the length or quality of life of patients with advanced GI cancer is still poor because of delayed diagnosis, recurrence and side effect. Resveratrol (3, 4, 5-trihydroxy-trans-stilbene; Res), a natural polyphenolic compound, reportedly has various pharmacologic functions including anti-oxidant, anti-inflammatory, anti-cancer, and cardioprotective functions. Many studies have demonstrated that Res also exerts a chemopreventive effect on GI cancer. Research investigating the anti-cancer mechanism of Res for the prevention and treatment of GI cancer has implicated multiple pathways including oxidative stress, cell proliferation, and apoptosis. Therefore, this paper provides a review of the function and molecular mechanisms of Res in the prevention and treatment of GI cancer.

The Effect of 4'-hydroxy-3,4,5-trimetoxystilbene, the Metabolite of Resveratrol Analogue DMU-212, on Growth, Cell Cycle and Apoptosis in DLD-1 and LOVO Colon Cancer Cell Lines

Resveratrol is a phytoalexin that naturally occurs in grapes, blueberries, cranberries, peanuts and many other plants. Although resveratrol inhibits carcinogenesis in all three stages, its clinical application is restricted due to poor pharmacokinetics. The methylated analogues of resveratrol have been found to have higher bioavailability and cytotoxic activity than that of the prototupe compound. Among the various methoxy derivatives of resveratrol, 3,4,5,4′-tetrametoxystilbene (DMU-212) is suggested to be one of the strongest activators of cytotoxicity and apoptosis. DMU-212 has been shown to exert anti-tumor activity in DLD-1 and LOVO colon cancer cells. Since colorectal cancer is the third most common cause of cancer-related deaths worldwide, the development of new anticancer agents is nowadays of high significance. The aim of the present study was to assess the anticancer activity of 4′-hydroxy-3,4,5-trimetoxystilbene (DMU-281), the metabolite of DMU-212, in DLD-1 and LOVO cell lines. We showed for the first time the cytotoxic activity of DMU-281 triggered via cell cycle arrest at G2/M phase and apoptosis induction accompanied by the activation of caspases-9, -8, -3/7. Furthermore, DMU-281 has been found to change the expression pattern of genes and proteins related to intrinsic as well as extrinsic apoptosis. Since the activation of these pathways of apoptosis is still the most desired strategy in anticancer research, DMU-281 seems to provide a promising approach to the treatment of colon cancer.

Methoxy-enriched cationic stilbenes as anticancer therapeutics

Stilbene-based compounds are largely described for their antioxidant activity. But their use as anticancer chemotherapeutics is hampered by poor pharmacokinetic properties and non-selectivity towards cancer and non-cancer potency. To overcome these drawbacks, twin chain cationic lipid conjugated, methoxy-enriched stilbene derivatives were designed, synthesized and evaluated for their anticancer potency. Our findings reveal that HMSC16, a molecule with the highest number of methoxy groups and with C16-twin chain lipid, is the most potent as well as the most selective anticancer agent when compared to the other synthesized derivatives and commercially available stilbene-based drug, tamoxifen, and resveratrol. To justify these results, we have conducted a series of mechanistic experiments where we found that HMSC16 induced ROS generation, apoptosis, and autophagy by affecting the mitochondrial, lysosomal and nuclear pathways. Further cell cycle analysis data reveals that HMSC16 not only induces cell death but is also involved in the arrest of the cell cycle at the sub-G1 phase. Moreover, HMSC16 showed self-aggregation property owing to a possibly favorable hydrophilic-lipophilic balance. The self-aggregation property of HMSC16 allowed it to entrap hydrophobic drugs, withaferin. With entrapped withaferin, HMSC16 showed additive if not synergistic cell killing effect in HeLa cells. From the above results, we concluded that HMSC16 can be used not just as a drug but also as a drug delivery agent.

The Effect of 3'-Hydroxy-3,4,5,4'-Tetramethoxy -stilbene, the Metabolite of the Resveratrol Analogue DMU-212, on the Motility and Proliferation of Ovarian Cancer Cells

Targeting tumor cell motility and proliferation is an extremely important challenge in the prevention of metastasis and improving the effectiveness of cancer treatment. We recently published data revealing that DMU-214, the metabolite of firmly cytotoxic resveratrol analogue DMU-212, exerted significantly higher biological activity than the parent compound in ovarian cancer cells. The aim of the present study was to assess the molecular mechanism of the potential anti-migration and anti-proliferative effect of DMU-214 in ovarian cancer cell line SKOV-3. We showed that DMU-214 reduced the migratory capacity of SKOV-3 cells. The microarray analysis indicated ontology groups of genes involved in processes of negative regulation of cell motility and proliferation. Furthermore, we found DMU-214 triggered changes in expression of several migration- and proliferation-related genes (SMAD7, THBS1, IGFBP3, KLF4, Il6, ILA, SOX4, IL15, SRF, RGCC, GPR56) and proteins (GPR56, RGCC, SRF, SMAD7, THBS1), which have been shown to interact to each other to reduce cell proliferation and motility. Our study showed for the first time that DMU-214 displayed anti-migratory and anti-proliferative activity in SKOV-3 ovarian cancer cells. On the basis of whole transcriptome analysis of these cells, we provide new insight into the role of DMU-214 in inhibition of processes related to metastasis.

Synthetic Imine Resveratrol Analog 2-Methoxyl-3,6-Dihydroxyl-IRA Ameliorates Colitis by Activating Protective Nrf2 Pathway and Inhibiting NLRP3 Expression

Resveratrol (RSV) is a naturally occurring polyphenol that exhibits pleiotropic health benefits, including anticolitis and colon cancer-protective activity. Recently, we identified the novel imine RSV analog (IRA), 2-methoxyl-3,6-dihydroxyl-IRA 3,4,5,4-tetramethoxystilbene (C33), as a putative activator of nuclear factor erythroid 2-related factor 2 (Nrf2). The present study was designed to evaluate the ability of C33 to activate the Nrf2 signaling pathway and its anticolitis effect in comparison to RSV. The anticolitis action of C33 was assessed in a mouse model of colitis induced by dextran sulfate sodium (DSS). The effect of C33 on the Nrf2 signaling pathway was examined in vitro and in vivo. Compared to RSV, C33 triggered a more dramatic increase in the expression of genes downstream of Nrf2 in LS174T cells as well as in the small intestine and colon of wild-type (WT) mice. Correlated with its superior ability to activate the cytoprotective Nrf2 pathway, C33 was significantly better in ameliorating DSS-induced colitis by improving the inflammation score, as well as downregulating the markers of inflammation in WT mice. Moreover, induction of the NOD-like receptors family pyrin domain containing 3 (NLRP3) inflammasome by colitis was also significantly inhibited by the IRA. Nrf2 knockout completely abolished the effects of C33, indicating that Nrf2 is the important mechanistic target of C33 in vivo. In conclusion, the novel IRA, C33, has stronger anticolitis effects than RSV. Further studies are warranted to evaluate C33 as a potential therapeutic agent for inflammatory bowel disease and cancer chemoprevention.

Design, synthesis and biological evaluation of a series of new resveratrol analogues as potential anti-cancer agents

A series of novel resveratrol derivatives were designed, synthesized and evaluated as anti-cancer agents. Most of the compounds showed significant anti-proliferative activities against three human cancer cell lines (HepG2, A549 and Hela). Among these compounds, compound r displayed the most potent inhibitory activity and showed low cytotoxic activity. Cell apoptosis and cell cycle assays demonstrated that compound r significantly induced apoptosis (p < 0.001) and arrested cell cycle at S phase. Immunofluorescence microscopy analysis showed compound r disrupted the tubulin network. Docking simulations supported the pharmacological results of compound r. It is believed that this work would be very useful for designing a new series of tubulin inhibitors.

Recent advances in the targeting of human DNA ligase I as a potential new strategy for cancer treatment

The emergence of drug resistance, coupled with the issue of low tumor selectivity and toxicity is a major pitfall in cancer chemotherapy. It has necessitated the urgent need for the discovery of less toxic and more potent new anti-cancer pharmaceuticals, which target the interactive mechanisms involved in division and metastasis of cancer cells. Human DNA ligase I (hligI) plays an important role in DNA replication by linking Okazaki fragments on the lagging strand of DNA, and also participates in DNA damage repair processes. Dysregulation of the functioning of such ligases can severely impact DNA replication and repair pathways events that are generally targeted in cancer treatment. Although, several human DNA ligase inhibitors have been reported in the literature but unfortunately not a single inhibitor is currently being used in cancer chemotherapy. Results of pre-clinical studies also support the fact that human DNA ligases are an attractive target for the development of new anticancer agents which work by the selective inhibition of rapidly proliferating cancer cells. In this manuscript, we discuss, in brief, the structure, synthesis, structure-activity-relationship (SAR) and anticancer activity of recently reported hLigI inhibitors.

Resveratrol induced premature senescence and inhibited epithelial-mesenchymal transition of cancer cells via induction of tumor suppressor Rad9

Resveratrol (RSV) has been reported to influence many biological processes, including the stimulation of cellular senescence and inhibition of epithelial-mesenchymal transition (EMT). In this research, we explored the mechanisms of RSV on EMT and cellular senescence through the expression of a DNA damage response (DDR) protein, Rad9, in breast and lung cancer cell lines. Upon treating breast and lung cancer cell lines with RSV at the concentrations of 10–50 μM, Rad9 expression was increased at both transcriptional and translational levels. The results indicated that RSV-induced Rad9 expression, mediated by DNA damage and ROS, can significantly suppress proliferation by activating cellular senescence, and diminishing the expression of EMT markers with concomitant downregulation of Slug in breast and lung cancer cell lines. By using a siRNA approach, RSV was shown to mediate cellular senescence and EMT through a Rad9-dependent mechanism. The treatment with RSV can inhibit the proliferation, EMT, and increase cellular senescence of breast and lung cancer cell lines by activating Rad9. Our results suggest that the breast and lung tumor suppressive activities of RSV are, at least in part, mediated by the upregulation of Rad9.

Resveratrol is a promising agent for colorectal cancer prevention and treatment: focus on molecular mechanisms

Colorectal cancer (CRC) is the third most common cancer and one of the main causes of cancer death entire the world. Environmental, dietary, and lifestyle factors including red meat consumption, cigarette smoking, alcohol intake and family history are the most important risk factors of CRC. Multiple pathways including inflammation, oxidative stress, and apoptosis are involved in its incidence and progression. Resveratrol, a polyphenolic compound, has different pharmacologic functions including anti-inflammation, cancer prevention, lipid-lowering effect, and hypoglycemic effect. Many studies have proved that resveratrol might also represent a chemo preventive effect on CRC. Thus, the aim of the current review is to depict the role of resveratrol in treatment of CRC in a molecular manner.

Increases in Colonic Bacterial Diversity after ω-3 Fatty Acid Supplementation Predict Decreased Colonic Prostaglandin E2 Concentrations in Healthy Adults

BACKGROUND

The intestinal microbiome is an important determinant of inflammatory balance in the colon that may affect response to dietary agents.

OBJECTIVE

This is a secondary analysis of a clinical trial, the Fish Oil Study, to determine whether interindividual differences in colonic bacteria are associated with variability in the reduction of colonic prostaglandin E2 (PGE2) concentrations after personalized supplementation with ω-3 (n-3) fatty acids.

METHODS

Forty-seven healthy adults (17 men, 30 women, ages 26-75 y) provided biopsy samples of colonic mucosa and luminal stool brushings before and after personalized ω-3 fatty acid supplementation that was based on blood fatty acid responses. Samples were analyzed using 16S ribosomal RNA sequencing. The data analyses focused on changes in bacterial community diversity. Linear regression was used to evaluate factors that predict a reduction in colonic PGE2.

RESULTS

At baseline, increased bacterial diversity, as measured by the Shannon and Inverse Simpson indexes in both biopsy and luminal brushing samples, was positively correlated with dietary fiber intakes and negatively correlated with fat intakes. Dietary supplementation with ω-3 fatty acids increased the Yue and Clayton community dis-similarity index between the microbiome in luminal brushings and colon biopsy samples post-supplementation (P = 0.015). In addition, there was a small group of individuals with relatively high Prevotella abundance who were resistant to the anti-inflammatory effects of ω-3 fatty acid supplementation. In linear regression analyses, increases in diversity of the bacteria in the luminal brushing samples, but not in the biopsy samples, were significant predictors of lower colonic PGE2 concentrations post-supplementation in models that included baseline PGE2, baseline body mass index, and changes in colonic eicosapentaenoic acid-to-arachidonic acid ratios. The changes in bacterial diversity contributed to 6-8% of the interindividual variance in change in colonic PGE2 (P = 0.001).

CONCLUSIONS

Dietary supplementation with ω-3 fatty acids had little effect on intestinal bacteria in healthy humans; however, an increase in diversity in the luminal brushings significantly predicted reductions in colonic PGE2. This trial was registered at www.clinicaltrials.gov as NCT01860352.

Anti-tumor Properties of Stilbene-based Resveratrol Analogues: Recent Results

Recent literature about stilbene-based analogues of resveratrol (1) has been reviewed, and a total of 94 compounds are reported (see structures 4 – 97), selected either for their promising anti-tumor properties or as comparative terms in SAR studies. As a general outline, these recent literature data confirm the previously reported observation that minimal modification in the nature and position of the substituents on the stilbene nucleus may cause large variations in their biological activity and, more specifically, in their anti-tumor properties. Among the polyhydroxylated stilbenes, it has been established that those with either a catechol or pyrogallol moiety are far better radical scavengers than either 1 or other analogues lacking an ortho-dihydroxy group, and this property was shown to be related to pro-apoptotic activity. In the large majority of cases where couples of E- and Z-isomers were evaluated for either cytotoxic or pro-apoptotic activity, the Z-isomers were significantly more active than their E analogues; nevertheless, a general rule stating that stilbenoids with Z configuration of the double bond display a considerably higher antiproliferative activity than their E-isomers cannot be considered as established. A variety of methoxystilbenes has been reported recently: in many cases these analogues showed either potent antiproliferative and pro-apoptotic activity or strong inhibition of TNFα-induced activation of NF- kB. Globally considered, polymethoxystilbenes are a sub-group of great interest among the resveratrol analogues: these analogues appear worthy of a deeper evaluation also in connection with their potential anti-angiogenic properties. In addition, in vivo studies indicate that methoxystilbenes undergo different metabolic conversion and have a higher bioavailability than resveratrol. The potent activity of some amino- and halogenated stilbenes is undoubtedly worthy of attention, but the toxicity of these compounds to normal cells has rarely been evaluated. In conclusion, the synthesis and evaluation of stilbene-based resveratrol analogues proved to be a highly active field of research and has recently afforded compounds with either cytotoxic or pro-apoptotic activity in the nanomolar range. Nevertheless, the exact structural determinants to optimize the anti-tumor properties of these compounds and details of their mechanism of action remain to be clarified.

The synthesis of 4,6-diaryl-2-pyridones and their bioactivation in CYP1 expressing breast cancer cells

As part of a programme to develop anticancer prodrugs which are activated by cytochrome P450 (CYP)1B1, a library of 4,6-diaryl-2-pyridones was synthesised in yields of 6-60% from the corresponding chalcones. A number of these derivatives showed promising antiproliferative activities in human breast cancer cell lines which express CYP1B1 and CYP1A1, while showing little toxicity towards a non-tumour breast cell line with no CYP expression. Metabolism studies provided evidence supporting the involvement of CYP1 enzymes in the bioactivation of these compounds.

Resveratrol enhances cisplatin-induced apoptosis in human hepatoma cells via glutamine metabolism inhibition

Cisplatin is one of the most effective chemotherapeutic drugs used in the treatment of HCC, but many patients will ultimately relapse with cisplatin-resistant disease. Used in combination with cisplatin, resveratrol has synergistic effect of increasing chemosensitivity of cisplatin in various cancer cells. However, the mechanisms of resveratrol enhancing cisplatin-induced toxicity have not been well characterized. Our study showed that resveratrol enhances cisplatin toxicity in human hepatoma cells via an apoptosis-dependent mechanism. Further studies reveal that resveratrol decreases the absorption of glutamine and glutathione content by reducing the expression of glutamine transporter ASCT2. Flow cytometric analyses demonstrate that resveratrol and cisplatin combined treatment leads to a significant increase in ROS production compared to resveratrol or cisplatin treated hepatoma cells alone. Phosphorylated H2AX (γH2AX) foci assay demonstrate that both resveratrol and cisplatin treatment result in a significant increase of γH2AX foci in hepatoma cells, and the resveratrol and cisplatin combined treatment results in much more γH2AX foci formation than either resveratrol or cisplatin treatment alone. Furthermore, our studies show that over-expression of ASCT2 can attenuate cisplatin-induced ROS production, γH2AX foci formation and apoptosis in human hepatoma cells. Collectively, our studies suggest resveratrol may sensitize human hepatoma cells to cisplatin chemotherapy via glutamine metabolism inhibition.

DHS (trans-4,4'-dihydroxystilbene) suppresses DNA replication and tumor growth by inhibiting RRM2 (ribonucleotide reductase regulatory subunit M2)

DNA replication machinery is responsible for accurate and efficient duplication of the chromosome. Since inhibition of DNA replication can lead to replication fork stalling, resulting in DNA damage and apoptotic death, inhibitors of DNA replication are commonly used in cancer chemotherapy. Ribonucleotide reductase (RNR) is the rate-limiting enzyme in the biosynthesis of deoxyribonucleoside triphosphates (dNTPs) that are essential for DNA replication and DNA damage repair. Gemcitabine, a nucleotide analog that inhibits RNR, has been used to treat various cancers. However, patients often develop resistance to this drug during treatment. Thus, new drugs that inhibit RNR are needed to be developed. In this study, we identified a synthetic analog of resveratrol (3,5,4’-trihydroxy-trans-stilbene), termed DHS (trans-4,4’-dihydroxystilbene), that acts as a potent inhibitor of DNA replication. Molecular docking analysis identified the RRM2 (ribonucleotide reductase regulatory subunit M2) of RNR as a direct target of DHS. At the molecular level, DHS induced cyclin F-mediated down-regulation of RRM2 by the proteasome. Thus, treatment of cells with DHS reduced RNR activity and consequently decreased synthesis of dNTPs with concomitant inhibition of DNA replication, arrest of cells at S-phase, DNA damage, and finally apoptosis. In mouse models of tumor xenografts, DHS was efficacious against pancreatic, ovarian, and colorectal cancer cells. Moreover, DHS overcame both gemcitabine resistance in pancreatic cancer and cisplatin resistance in ovarian cancer. Thus, DHS is a novel anti-cancer agent that targets RRM2 with therapeutic potential either alone or in combination with other agents to arrest cancer development.

Higher baseline expression of the PTGS2 gene and greater decreases in total colonic fatty acid content predict greater decreases in colonic prostaglandin-E2 concentrations after dietary supplementation with ω-3 fatty acids

This study evaluated whether mRNA expression of major genes regulating formation of prostaglandin (PG)E2 in the colon and colonic fatty acid concentrations are associated with the reduction in colonic mucosal PGE2 after dietary supplementation with omega-3 (ω-3) fatty acids. Supplementation with ω-3 fatty acids was done for 12 weeks using personalized dosing that was expected to reduce colonic PGE2 by 50%. In stepwise linear regression models, the ω-3 fatty acid dose and baseline BMI explained 16.1% of the inter-individual variability in the fold change of colonic PGE2 post-supplementation. Increases in mRNA gene expression after supplementation were, however, modest and were not associated with changes in PGE2. When baseline expression of PTGS1, PTGS2 and HPGD genes was included in the linear regression model containing dose and BMI, only PTGS2, the gene coding for the inducible form cyclooxygenase, was a significant predictor. Higher relative expression of PTGS2 predicted greater decreases in colonic PGE2, accounting for an additional 13.6% of the inter-individual variance. In the final step of the regression model, greater decreases in total colonic fatty acid concentrations predicted greater decreases in colonic PGE2, contributing to an additional 18.7% of the variance. Overall, baseline BMI, baseline expression of PTGS2 and changes in colonic total fatty acids together accounted for 48% of the inter-individual variability in the change in colonic PGE2. This is consistent with biochemical data showing that fatty acids which are not substrates for cyclooxygenases can activate cyclooxygenase-2 allosterically. Further clinical trials are needed to elucidate the factors that regulate the fatty acid milieu of the human colon and how this interacts with key lipid metabolizing enzymes. Given the central role of PGE2 in colon carcinogenesis, these pathways may also impact on colon cancer prevention by other dietary and pharmacological approaches.

Cytotoxic, tubulin-interfering and proapoptotic activities of 4'-methylthio-trans-stilbene derivatives, analogues of trans-resveratrol

The aim of this study was to evaluate the cytotoxicity of a series of seven 4'-methylthio-trans-stilbene derivatives against cancer cells: MCF7 and A431 in comparison with non-tumorigenic MCF12A and HaCaT cells. The mechanism of anti-proliferative activity of the most cytotoxic trans-resveratrol analogs: 3,4,5-trimethoxy-4'-methylthio-trans-stilbene (3,4,5-MTS) and 2,4,5-trimethoxy-4'-methylthio-trans-stilbene (2,4,5-MTS) was analyzed and compared with the effect of trans-resveratrol. All the compounds that were studied exerted a stronger cytotoxic effect than trans-resveratrol did. MCF7 cells were the most sensitive to the cytotoxic effect of trans-resveratrol analogs with IC50 in the range of 2.1-6.0 µM. Comparing the cytotoxicity of 3,4,5-MTS and 2,4,5-MTS, a significantly higher cytotoxic activity of these compounds against MCF7 versus MCF12A was observed, whereas no significant difference was observed in cytotoxicity against A431 and HaCaT. In the series of 4'-methylthio-trans-stilbenes, 3,4,5-MTS and 2,4,5-MTS were the most promising compounds for further mechanistic studies. The proapoptotic activity of 3,4,5-MTS and 2,4,5-MTS, estimated with the use of annexin-V/propidium iodide assay, was comparable to that of trans-resveratrol. An analysis of cell cycle distribution showed a significant increase in the percentage of apoptotic cells and G2/M phase arrest in MCF7 and A431 as a result of treatment with 3,4,5-MTS, whereas trans-resveratrol tended to increase the percentage of cells in S phase, particularly in epithelial breast cells MCF12A and MCF7. Both trans-stilbene derivatives enhanced potently tubulin polymerization in a dose-dependent manner with sulfur atom participating in the interactions with critical residues of the paclitaxel binding site of β-tubulin.

Alteration of benzo(a)pyrene biotransformation by resveratrol in ApcMin/+ mouse model of colon carcinogenesis

Epidemiological surveys have revealed that environmental and dietary factors contribute to most of the human cancers. Our earlier studies have shown that resveratrol (RVT), a phytochemical reduced the tumor number, size and incidence of dysplasias induced by benzo(a)pyrene (BaP), an environmental toxicant in the Apc^Min/+ mouse model of colon cancer. In this study we investigated to ascertain whether the preventive effects of RVT on BaP-induced colon carcinogenesis is a result of altered BaP biotransformation by RVT. For the first group of mice, 100 μg BaP/kg bw was administered in peanut oil via oral gavage over a 60 day period. For the second group, 45 μg RVT/kg bw was co-administered with BaP. For the third group, RVT was administered for 1 week prior to BaP exposure. Blood, colon and liver were collected from control and BaP/RVT-treated mice at 60 days post-BaP & RVT exposure. We have assayed activities and expression (protein & mRNA) of drug metabolizing enzymes such as cytochrome P4501A1 (CYP1A1), CYP1B1, and glutathione-S-transferase (GST) in colon and liver samples from the treatment groups mentioned above. An increased expression of CYP1A1 in liver and colon and of CYP1B1 in liver of BaP-treated mice was seen, while RVT inhibited the extent of biotransformation mediated by these enzymes in the respective tissue samples. In the case of GST, an increased expression in colon of BaP alone-treated mice was noted when RVT was administered prior to BaP or simultaneously with BaP. However, there is no change in liver GST expression between BaP and RVT treatment groups. The concentrations of BaP aqueous (phase II) metabolites were found to be greater than the organic (phase I) metabolites, suggesting that RVT slows down the phase I metabolism (metabolic activation) of BaP, while enhancing phase II metabolism (detoxification). Additionally, the BaP-DNA adduct concentrations measured in colon and liver of BaP + RVT-treated mice were low relative to their BaP counterparts. Taken together, our findings strongly suggest that RVT alleviates BaP-induced colon carcinogenesis by impairing biotransformation pathways and DNA adduct formation, and therefore holds promise as a chemopreventive agent.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.

Effects of a Grapevine Shoot Extract Containing Resveratrol and Resveratrol Oligomers on Intestinal Adenoma Development in Mice: In Vitro and In Vivo Studies

SCOPE

Evidence suggests that the dietary consumption of plant extracts containing polyphenols might help prevent the onset of cancers of the gastrointestinal tract. In the present study, the chemopreventive and antiproliferative efficacy of a grapevine shoot extract (Vineatrol®30) containing resveratrol and resveratrol oligomers is investigated in vivo and in vitro.

METHODS AND RESULTS

The in vivo study is performed using Apc^Min mice on a high-fat diet, which represents a model of human adenomatous polyposis, while the potential of the extract as well as some of its isolated constituents to inhibit intestinal adenoma cell proliferation in vitro is investigated using APC10.1 cells derived from an Apc^Min mouse. Vineatrol®30 at a low (2.3 mg kg^-1  diet) or high dose (476 mg kg^-1  diet) reduces the adenoma number in male and adenoma volume in female animals. Furthermore, Vineatrol®30 as well as resveratrol and two resveratrol tetramers compromise the expansion of APC10.1 cells by reducing cell number, inducing cell cycle arrest, cellular senescence, and apoptosis. However, except for the extract, none of the isolated resveratrol oligomers is more efficacious than resveratrol in these cells.

CONCLUSION

Vineatrol®30 may merit further investigation as a potential dietary gastrointestinal cancer chemopreventive agent in humans.

The Role of Resveratrol in Cancer Therapy

Natural product compounds have recently attracted significant attention from the scientific community for their potent effects against inflammation-driven diseases, including cancer. A significant amount of research, including preclinical, clinical, and epidemiological studies, has indicated that dietary consumption of polyphenols, found at high levels in cereals, pulses, vegetables, and fruits, may prevent the evolution of an array of diseases, including cancer. Cancer development is a carefully orchestrated progression where normal cells acquires mutations in their genetic makeup, which cause the cells to continuously grow, colonize, and metastasize to other organs such as the liver, lungs, colon, and brain. Compounds that modulate these oncogenic processes can be considered as potential anti-cancer agents that may ultimately make it to clinical application. Resveratrol, a natural stilbene and a non-flavonoid polyphenol, is a phytoestrogen that possesses anti-oxidant, anti-inflammatory, cardioprotective, and anti-cancer properties. It has been reported that resveratrol can reverse multidrug resistance in cancer cells, and, when used in combination with clinically used drugs, it can sensitize cancer cells to standard chemotherapeutic agents. Several novel analogs of resveratrol have been developed with improved anti-cancer activity, bioavailability, and pharmacokinetic profile. The current focus of this review is resveratrol’s in vivo and in vitro effects in a variety of cancers, and intracellular molecular targets modulated by this polyphenol. This is also accompanied by a comprehensive update of the various clinical trials that have demonstrated it to be a promising therapeutic and chemopreventive agent.

The Anti-inflammatory Effect of Personalized Omega-3 Fatty Acid Dosing for Reducing Prostaglandin E2 in the Colonic Mucosa Is Attenuated in Obesity

This clinical trial developed a personalized dosing model for reducing prostaglandin E₂ (PGE₂) in colonic mucosa using ω-3 fatty acid supplementation. The model utilized serum eicosapentaenoic acid (EPA, ω-3):arachidonic acid (AA, ω-6) ratios as biomarkers of colonic mucosal PGE₂ concentration. Normal human volunteers were given low and high ω-3 fatty acid test doses for 2 weeks. This established a slope and intercept of the line for dose versus serum EPA:AA ratio in each individual. The slope and intercept was utilized to calculate a personalized target dose that was given for 12 weeks. This target dose was calculated on the basis of a model, initially derived from lean rodents, showing a log-linear relationship between serum EPA:AA ratios and colonic mucosal PGE₂ reduction. Bayesian methods allowed addition of human data to the rodent model as the trial progressed. The dosing model aimed to achieve a serum EPA:AA ratio that is associated with a 50% reduction in colonic PGE₂ Mean colonic mucosal PGE₂ concentrations were 6.55 ng/mg protein (SD, 5.78) before any supplementation and 3.59 ng/mg protein (SD, 3.29) after 12 weeks of target dosing. In secondary analyses, the decreases in PGE₂ were significantly attenuated in overweight and obese participants. This occurred despite a higher target dose for the obese versus normal weight participants, as generated by the pharmacodynamic predictive model. Large decreases also were observed in 12-hydroxyicosatetraenoic acids, and PGE₃ increased substantially. Future biomarker-driven dosing models for cancer prevention therefore should consider energy balance as well as overall eicosanoid homeostasis in normal tissue. Cancer Prev Res; 10(12); 729-37. ©2017 AACR.

Prolonged exposure of resveratrol induces reactive superoxide species-independent apoptosis in murine prostate cells

Nitric oxide, a signaling molecule, inhibits mitochondrial respiration by binding with cytochrome c oxidase, resulting in elevated production of reactive superoxide species (reactive oxygen and nitrogen) in the mitochondria and increased susceptibility to cell death. Generation of mitochondrial superoxide species can be suppressed by natural compounds such as resveratrol, a dietary polyphenol found in the skin of red fruits. In various cancer cells, resveratrol shows anti-oxidant and cancer preventive properties. Since, the effect of resveratrol on reactive superoxide species-independent apoptosis in prostate cancer cells is not well illustrated; therefore, we investigated this phenomenon in TRAMP murine prostate cancer cells. To accomplish this, TRAMP cells were incubated with resveratrol, resveratrol + DETA-NONOate, DETA-NONOate (nitric oxide donor), resveratrol + L-NMMA, or L-NMMA (nitric oxide inhibitor) for 48 h, and reactive superoxide species in the mitochondria and culture supernatant were measured. In addition, the mitochondrial membrane potential, cell viability, expression of apoptotic markers (Bax and Bcl2), γ-H2A.x, p53, and caspase-3 was determined. We found that resveratrol suppressed reactive superoxide species such as reactive oxygen species in the mitochondria and nitric oxide in culture supernatant when compared to the DETA-NONOate treatment and disrupted the mitochondrial membrane potential. Resveratrol also reduced cell viability, altered the expression of apoptotic markers (Bax and Bcl2), and increased expression of γ-H2A.x (indicative marker of DNA fragmentation) and p53 (a critical DNA damage response protein). However, there was no appreciable modulation of the caspase-3. Therefore, our data suggest that resveratrol induces superoxide species-independent apoptosis and may act as a therapeutic agent against prostate cancer.

The therapeutic potential of resveratrol: a review of clinical trials

Resveratrol is a nutraceutical with several therapeutic effects. It has been shown to mimic effects of caloric restriction, exert anti-inflammatory and anti-oxidative effects, and affect the initiation and progression of many diseases through several mechanisms. While there is a wealth of in vitro and in vivo evidence that resveratrol could be a promising therapeutic agent, clinical trials must confirm its potential. In this work, we reviewed the current clinical data available regarding the pharmacological action of resveratrol. Most of the clinical trials of resveratrol have focused on cancer, neurological disorders, cardiovascular diseases, diabetes, non-alcoholic fatty liver disease (NAFLD), and obesity. We found that for neurological disorders, cardiovascular diseases, and diabetes, the current clinical trials show that resveratrol was well tolerated and beneficially influenced disease biomarkers. However resveratrol had ambiguous and sometimes even detrimental effects in certain types of cancers and in NAFLD. In most of the clinical trials, the major obstacle presented was resveratrol’s poor bioavailability. Thus, this work provides useful considerations for the planning and design of future pre-clinical and clinical research on resveratrol.

Development and validation of HPLC-MS/MS procedure for determination of 3,4,4',5-tetra-methoxystilbene (DMU-212) and its metabolites in ovarian cancer cells and culture medium

The synthetic resveratrol analogue DMU-212 (3,4,4',5-tetramethoxystilbene) has been shown to possess stronger anticancer activity than resveratrol in a variety of tumour cells. To date, there has been no appropriate procedure that would ensure a reliable data about levels of metabolic products of DMU-212 in cancer cell lines. The purpose of this study was to develop a new procedure for determination of DMU-212 and its three metabolites (DMU-214, DMU-281, DMU-291) in cell lines. Analyses were performed using an HPLC system coupled with a triple quadrupole mass spectrometer operating in multiple reaction monitoring mode. Separation was conducted using a C18 column at a flow rate 800μL/min with a mobile phase consisting of 5mM ammonium acetate with 0.1% formic acid (solvent A) and acetonitrile (solvent B). The new methodology is fast, simple and has excellent specificity. Moreover, it showed good linearity in two matrices - cell lysates and culture media. Accuracy values for analytes evaluated at different concentration levels ranged from 0.43 to 18% (%bias). The intra-day and inter-day precision, expressed as CV, was in a range 0.49-5.5% and 0.83-13%, respectively. The validated procedure was successfully applied to quantify the resveratrol analogues in the human ovarian cancer cell line SKOV3.

Anticancer Activity of Stilbene-Based Derivatives

Stilbene is an abundant structural scaffold in nature, and stilbene-based compounds have been widely reported for their biological activity. Notably, (E)-resveratrol and its natural stilbene-containing derivatives have been extensively investigated as cardioprotective, potent antioxidant, anti-inflammatory, and anticancer agents. Starting from its potent chemotherapeutic activity against a wide variety of cancers, the stilbene scaffold has been subject to synthetic manipulations with the aim of obtaining new analogues with improved anticancer activity and better bioavailability. Within the last decade, the majority of new synthetic stilbene derivatives have demonstrated significant anticancer activity against a large number of cancer cell lines, depending on the type and position of substituents on the stilbene skeleton. This review focuses on the structure-activity relationship of the key compounds containing a stilbene scaffold and describes how the structural modifications affect their anticancer activity.

Growth-Inhibiting Activity of Resveratrol Imine Analogs on Tumor Cells In Vitro

Although resveratrol exerts manifold antitumorigenic effects in vitro, its efficacy against malignancies in vivo seems limited. This has been increasingly recognized in recent years and has prompted scientists to search for structurally related compounds with more promising anticarcinogenic and/or pharmacokinetic properties. A class of structurally modified resveratrol derivatives, so-called resveratrol imine analogs (IRA's), might meet these requirements. Therefore, the biological activity of five of these compounds was examined and compared to that of resveratrol. Firstly, the antiproliferative potency of all five IRA's was investigated using the p53 wildtype-carrying colorectal carcinoma cell line HCT-116wt. Then, using the former and a panel of various other tumor cell lines (including the p53 knockout variant HCT-116p53-/-), the growth-inhibiting and cell cycle-disturbing effects of the most potent IRA (IRA 5, 2-[[(2-hydroxyphenyl)methylene]amino]-phenol) were studied as was its influence on cyclooxygenase-2 expression and activity. Finally, rat liver microsomes were used to determine the metabolic stability of that compound. IRA 5 was clearly the most potent compound in HCT-116wt cells, with an unusually high IC50-value of 0.6 μM. However, in the other five cell lines used, the antiproliferative activity was mostly similar to resveratrol and the effects on the cell cycle were heterogeneous. Although all cell lines were affected by treatment with IRA 5, cells expressing functional p53 seemed to react more sensitively, suggesting that this protein plays a modulating role in the induction of IRA 5-mediated biological effects. Lastly, IRA 5 led to contradictory effects on cyclooxygenase-2 expression and activity and was less glucuronidated than resveratrol. As IRA 5 is approximately 50 times more toxic towards HCT-116wt cells, exerts different effects on the cyclooxygenase-2 and is metabolized to a lesser extent, it shows certain advantages over resveratrol and could therefore serve as basis for additional chemical modifications, potentially yielding compounds with more favorable biological and pharmacokinetic features.

Resveratrol analogue, HS-1793, induces apoptotic cell death and cell cycle arrest through downregulation of AKT in human colon cancer cells

Resveratrol, a polyphenolic compound, is a naturally occurring phytochemical and is found in a variety of plants, including grapes, berries and peanuts. It has gained much attention for its potential anticancer activity against various types of human cancer. However, the usefulness of resveratrol as a chemotherapeutic agent is limited by its photosensitivity and metabolic instability. In this study the effects of a synthetic analogue of resveratrol, HS-1793, on the proliferation and apoptotic cell death were investigated using HCT116 human colon cancer cells. Although this compound has been reported to have anticancer activities in several human cancer cell lines, the therapeutic effects of HS-1793 on human colon cancer and its mechanisms of action have not been extensively studied. HS-1793 inhibited cell growth and induced apoptotic cell death in a concentration-dependent fashion. Induction of apoptosis was determined by morphological changes, cleavage of poly(ADP-ribose) polymerase, alteration of Bax/Bcl-2 expression ratio, and caspase activations. Flow cytometric analysis revealed that HS-1793 induced G2/M arrest in the cell cycle progression in HCT116 cells. Furthermore, HS-1793 showed more potent anticancer effects in several aspects than resveratrol in HCT116 cells. In addition, HS-1793 suppressed Akt and the phosphatidylinositol-3 kinase/Akt inhibitor LY294002 was found to enhance its induction of apoptosis. Thus, these findings suggest that HS-1793 have potential as a candidate chemotherapeutic agent against human colon cancer.

3'-hydroxy-3,4,5,4'-tetramethoxystilbene, the metabolite of resveratrol analogue DMU-212, inhibits ovarian cancer cell growth in vitro and in a mice xenograft model

In screening studies, the cytotoxic activity of four metabolites of resveratrol analogue 3,4,5,4′-tetramethoxystilbene (DMU-212) against A-2780 and SKOV-3 ovarian cancer cells was investigated. The most active metabolite, 3′-hydroxy-3,4,5,4′-tetramethoxystilbene (DMU-214), was chosen for further studies. The cytotoxicity of DMU-214 was shown to be higher than that of the parent compound, DMU-212, in both cell lines tested. Since DMU-212 was supposed to undergo metabolic activation through its conversion to DMU-214, an attempt was made to elucidate the mechanism of its anti-proliferative activity. We found that in SKOV-3 cells lacking p53, DMU-214 induced receptor-mediated apoptosis. In A-2780 cell line with expression of wild-type p53, DMU-214 modulated the expression pattern of p53-target genes driving intrinsic and extrinsic apoptosis pathways, as well as DNA repair and damage prevention. Regardless of the up-regulation of p48, p53R2, sestrins and Gaad45 genes involved in cancer cell DNA repair, we demonstrated the stronger anti-proliferative and pro-apoptotic effects of DMU-214 in A-2780 cells when compared to those in SKOV-3. Hence we verified DMU-214 activity in the xenograft model using SCID mice injected with A-2780 cells. The strong anti-proliferative activity of DMU-214 in the in vivo model allowed to suggest the tested compound as a potential therapeutic in ovarian cancer treatment.

Identification of resveratrol derivative 3,3',4,4',5,5'-hexamethoxy- trans-stilbene as a novel pro-angiogenic small-molecule compound

The potential to promote neovascularization in ischemic tissues using exogenous agents is an attractive avenue for therapeutics. To identify novel pro-angiogenic small-molecule compound, we screened a series of resveratrol methylated derivatives and identified 3,3',4,4', 5,5'-hexamethoxy-trans-stilbene (3,3',4,4',5,5'-HMS) potently promotes proliferation, migration, invasion and tube formation of human umbilical vein VECs (HUVECs) in vitro. Furthermore, 3,3',4,4',5,5'-HMS accelerates neo-vessels sprouting of rat aortic rings ex vivo, and neovascularization of chick chorioallantoic membrane (CAM) and mouse matrigel plugs in vivo. Microarray analyses show that the level of early growth response 1 (EGR-1), an inducible pro-angiogenic gene regulatory factor, was upregulated. The upregulation of EGR-1 was confirmed by semiquantitative RT-PCR, quantitative real-time PCR and western blotting analyses. In addition, the levels of several pro-angiogenic factors including transforming growth factor β1 (TGF-β1), vascular endothelial growth factor (VEGF), nitric oxide (NO), and the activity of endothelial NO synthase (eNOS) were elevated in 3,3',4,4',5,5'-HMS-treated HUVECs. Inhibition of NO synthase by l-NAME blocked the pro-angiogenic effects of 3,3',4,4',5,5'-HMS. Our research shows that 3,3',4,4',5,5'-HMS dramatically promoted angiogenesis in vitro, ex vivo and in vivo, which might represent a novel potential agent for the development of therapeutic drugs to treat ischemic diseases.

The resveratrol analogue, 3,4,5,4'‑trans-tetramethoxystilbene, inhibits the growth of A375 melanoma cells through multiple anticancer modes of action

Resveratrol is a natural dietary product that has demonstrated multifaceted anticancer activity. Several analogues of resveratrol have been synthesized in an effort to enhance the pharmacological potency and improve the pharmacokinetic properties of the compound. 3,4,5,4'‑trans‑tetramethoxystilbene (3,4,5,4'‑TMS) is a methoxylated analogue of resveratrol that has demonstrated anti-proliferative activity in vitro (in cancer cell lines) and in vivo (in xenograft models). In the present study, the anticancer effects of 3,4,5,4'‑TMS in A375 human melanoma cells were examined. 3,4,5,4'‑TMS markedly inhibited the proliferation of A375 cells (IC50=0.7 µM), via a mechanism involving mitotic arrest at the prometaphase stage of cell division. This effect was accompanied by the upregulation of the expression of the mitogen activated protein kinases, JNK and p38, and the concomitant activation of p38, that was verified by the nuclear translocation of the phoshorylated form of the protein. The pharmacological inhibition of p38 by SB203580 (4 µM) attenuated the effects of 3,4,5,4'‑TMS, as demonstrated by decreased cell cycle progression at the mitotic phase. Furthermore, 3,4,5,4'‑TMS increased the total levels of Aurora A, while it inhibited the localization of the protein to the spindle poles. Finally, 3,4,5,4'‑TMS exhibited anti-metastatic activity, inhibiting A375 cell migration and the attachment of the cells to a collagen type IV-coated surface. Collectively, the data suggest that 3,4,5,4'‑TMS is an effective chemotherapeutic drug for the treatment of human melanoma and that it exerts its effects through multiple anticancer modes of action.

Effect of resveratrol analogue, DMU-212, on antioxidant status and apoptosis-related genes in rat model of hepatocarcinogenesis

The aim of the study was to examine whether antioxidant properties of 3,4,4',5-tetramethoxystilbene (DMU-212) contribute to its anticarcinogenic activity and whether DMU-212 affects the expression of apoptosis-related genes. Two-stage model of hepatocarcinogenesis was used; male Wistar rats were challenged with N-nitrosodiethylamine (NDEA), 200 mg/kg body weight (b.w.), intraperitoneal, then phenobarbital (PB) in drinking water (0.05%) was administered. Simultaneously, DMU-212 was given per os at a dose 20 or 50 mg/kg b.w. two times a week for 16 weeks. DMU-212 caused a moderate decrease in hepatic thiobarbituric acid reactive substances and protein carbonyls concentration elevated in rats treated with NDEA/PB. The activity of antioxidant enzymes examined reduced by NDEA/PB treatment was not restored in rats coadministered with DMU-212. Effects of DMU-212 on messenger RNA (mRNA) expression of antioxidant enzymes in rats challenged with NDEA/PB were diversified; no changes in their protein expression were noted in any of the groups. The expression of 17,000 genes was analyzed by Affymetrix® Rat Gene 1.1 ST Array; 15 apoptosis-related genes were selected and validated by RT-q PCR. The combined treatment with NDEA/PB and DMU-212 increased the mRNA level of some genes driving mitochondria-mediated apoptosis, whereas the mRNA expression of some anti-apoptotic genes triggering receptor-mediated apoptosis was reduced. The expression of genes encoding caspases-4, -8, -9, and -12 was also increased in rats treated with DMU-212. Although antioxidant effect of DMU-212 in rats challenged with NDEA/PB was moderate, its potential anticarcinogenic properties were demonstrated as evidenced by modulation of apoptosis-related genes.