Resveratrol modulates rat macrophage functions

Structural characteristics of sulfated polysaccharides from Sargassum horneri and immune-enhancing activity of polysaccharides combined with lactic acid bacteria

Sargassum horneri (SH), a marine brown alga, is known to contain a variety of bioactive ingredients and previous studies reported sulfated polysaccharides in SH as a potential candidate for a functional ingredient. However, immune-enhancing activity combined with Lactobacillus plantarum (LAB) is not yet studied. In the present study, we attempted to characterize sulfated polysaccharides (SHCPs) in SH by MALDI-TOF/TOF mass spectrometry and evaluate their immune-enhancing effect on macrophage cells. The main residue of SHCPs in SH is 2-sulfated 1,4-linked L-fucose and this epitope combined with LAB shows immune enhancement properties through cytokine production at the cellular level and increases the population of lymphocytes and myelomonocytes in the adult zebrafish kidney. These results indicate that SHCPs, along with LAB, have potent immune-enhancing activity and may be utilized as a potential immunomodulatory ingredient.

Sargachromenol Isolated from Sargassum horneri Inhibits Particulate Matter-Induced Inflammation in Macrophages through Toll-like Receptor-Mediated Cell Signaling Pathways

Sargassum horneri is an invasive brown seaweed that grows along the shallow coastal areas of the Korean peninsula, which are potentially harmful to fisheries and natural habitats in the areas where it is accumulated. Therefore, the author attempted to evaluate the anti-inflammatory mechanism of Sargachromenol isolated from S. horneri against particulate matter (PM)-stimulated RAW 264.7 macrophages. PM is a potent inducer of respiratory diseases such as lung dysfunctions and cancers. In the present study, the anti-inflammatory properties of Sargachromenol were validated using enzyme-linked immunosorbent assay (ELISA), Western blots, and RT-qPCR experiments. According to the results, Sargachromenol significantly downregulated the PM-induced proinflammatory cytokines, Prostaglandin E2 (PGE2), and Nitric Oxide (NO) secretion via blocking downstream activation of Toll-like receptor (TLR)-mediated nuclear factor kappa B (NF-κB) and MAPKs phosphorylation. Thus, Sargachromenol is a potential candidate for innovation in various fields including pharmaceuticals, cosmeceuticals, and functional food.

Natural Products for Regulating Macrophages M2 Polarization

Macrophages M2 polarization have been taken as an anti-inflammatory progression during inflammation. Natural plant-derived products, with potential therapeutic and preventive activities against inflammatory diseases, have received increasing attention in recent years because of their whole regulative effects and specific pharmacological activities. However, the molecular mechanisms about how different kinds of natural compounds regulate macrophages polarization still unclear. Therefore, in the current review, we summarized the detailed research progress on the active compounds derived from herbal plants with regulating effects on macrophages, especially M2 polarization. These natural occurring compounds including flavonoids, terpenoids, glycosides, lignans, coumarins, alkaloids, polyphenols and quinones. In addition, we extensively discussed the cellular mechanisms underlying the M2 polarization for each compound, which could provide potential therapeutic strategies aiming macrophages M2 polarization.

Development, Characterization, and In Vitro Evaluation of Resveratrol-Loaded Poly-(ε-caprolactone) Microcapsules Prepared by Ultrasonic Atomization for Intra-Articular Administration

Intra-articular administration of drugs to the joint in the treatment of joint disease has the potential to minimize the systemic bioavailability and the usual side-effects associated with oral drug administration. In this work, a drug delivery system is proposed to achieve an anti-inflammatory local effect using resveratrol (RSV). This study aims to develop microcapsules made of poly-(ε-caprolactone) (PCL) by ultrasonic atomization to preserve the antioxidant activity of RSV, to prevent its degradation and to suppress the inflammatory response in activated RAW 264.7 macrophages. An experimental design was performed to build a mathematical model that could estimate the effect of nozzle power and polymer concentration on particle size and encapsulation efficiency. RSV-loaded microcapsules showed adequate morphology, particle size, and loading efficiency properties. RSV formulations exhibited negligible cytotoxicity and an efficient amelioration of inflammatory responses, in terms of Nitric Oxide (NO), ROS (Reactive Oxygen Species), and lipid peroxidation in macrophages. Thus, RSV-loaded microcapsules merit consideration as a drug delivery system suitable for intra-articular administration in inflammatory disorders affecting the joint.

Influence of trans-resveratrol on macrophage and lymphocyte activity in rainbow trout (Oncorhynchus mykiss) - in vitro study

The objective of this study was to investigate the effect of trans-resveratrol, a potent antioxidant with anti-inflammatory and chemopreventive properties, naturally occurring in many fruits and plants on lymphocytes proliferation and also on macrophages metabolic and phagocytic activity. The aim of this study was to demonstrate the immunomodulatory effects of the compound on fish immunocompetent cells and determine the type of this interaction (immunosuppression or immunostimulation). Proliferative activity of lymphocytes was studied by MTT assay, and the respiratory burst was evaluated using the respiratory burst activity (RBA) test. Phagocytic killing was tested using the PKA test. The experiment have shown that trans-resveratrol suppressed blood B cells, while there was no significant influence on blood T lymphocytes. However, insignificant stimulatory effect occurred at the lowest concentration. In addition, the compound inhibited proliferation of T and B lymphocytes isolated from the organs. Importantly, trans-resveratrol caused stimulation of blood and organs macrophages phagocytic killing, and also increased the respiratory burst of macrophages isolated from organ. These results suggest a potential use of trans-resveratrol as an immunomodulator of innate immunity in fish. This is particularly important, as this kind of resistance plays leading role in protecting the body against infection. In comparison, adaptive immunity is slower and also much less precise.

In vitro and in vivo anti-inflammatory activities of high molecular weight sulfated polysaccharide; containing fucose separated from Sargassum horneri: Short communication

Recent studies on crude and pure compounds from Sargassum horneri have shown promising bioactive properties. However, anti-inflammatory potentials of fucose-rich sulfated polysaccharides from S. horneri have not yet been discovered. In the present study, we evaluated the in vitro and in vivo anti-inflammatory activities of four polysaccharide fractions separated from membrane filters according to their molecular weights (<5kDa (f1), 5-10kDa (f2), 10-30kDa (f3), and >30kDa (f4)). According to the results, F4 fraction inhibited the lipopolysaccharides (LPS)-induced nitric oxide (NO) (IC50=87.12μg/mL) and prostaglandin E2 production as well as pro-inflammatory cytokine production in RAW 264.7 cells through down-regulating nuclear factor-κB signaling cascade. According to the results, f4 has a potential to down-regulate LPS-induced toxicity, cell death and NO production levels in LPS-induced in vivo zebrafish embryo model. These results suggest that f4 fraction has the potential to develop functional materials or drugs to treat inflammatory diseases.

Anti-inflammatory activity of a sulfated polysaccharide isolated from an enzymatic digest of brown seaweed Sargassum horneri in RAW 264.7 cells

BACKGROUND/OBJECTIVES

Sargassum horneri is an edible brown alga that grows in the subtidal zone as an annual species along the coasts of South Korea, China, and Japan. Recently, an extreme amount of S. horneri moved into the coasts of Jeju Island from the east coast of China, which made huge economic and environmental loss to the Jeju Island. Thus, utilization of this biomass becomes a big issue with the local authorities. Therefore, the present study was performed to evaluate the anti-inflammatory potential of crude polysaccharides (CPs) extracted from S. horneri China strain in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells.

MATERIALS/METHODS

CPs were precipitated from S. horneri digests prepared by enzyme assistant extraction using four food-grade enzymes (AMG, Celluclast, Viscozyme, and Alcalase). The production levels of nitric oxide (NO) and pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin (IL)-1β were measured by Griess assay and enzyme-linked immunosorbent assay, respectively. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPKs) were measured by using western blot. The IR spectrums of the CPs were recorded using a fourier transform infrared spectroscopy (FT-IR) spectrometer.

RESULTS

The polysaccharides from the Celluclast enzyme digest (CCP) showed the highest inhibition of NO production in LPS-stimulated RAW 264.7 cells (IC₅₀ value: 95.7 µg/mL). Also, CCP dose-dependently down-regulated the protein expression levels of iNOS and COX-2 as well as the production of inflammatory cytokines, including TNF-α and IL-1β, compared to the only LPS-treated cells. In addition, CCP inhibited the activation of NF-κB p50 and p65 and the phosphorylation of MAPKs, including p38 and extracellular signal-regulated kinase, in LPS-stimulated RAW 264.7 cells. Furthermore, FT-IR analysis showed that the FT-IR spectrum of CCP is similar to that of commercial fucoidan.

CONCLUSIONS

Our results suggest that CCP has anti-inflammatory activities and is a potential candidate for the formulation of a functional food ingredient or/and drug to treat inflammatory diseases.

Phytochemicals and their impact on adipose tissue inflammation and diabetes

Type 2 diabetes mellitus is an inflammatory disease and the mechanisms that underlie this disease, although still incompletely understood, take place in the adipose tissue of obese subjects. Concurrently, the prevalence of obesity caused by Western diet's excessive energy intake and the lack of exercise escalates, and is believed to be causative for the chronic inflammatory state in adipose tissue. Overnutrition itself as an overload of energy may induce the adipocytes to secrete chemokines activating and attracting immune cells to adipose tissue. But also inflammation-mediating food ingredients like saturated fatty acids are believed to directly initiate the inflammatory cascade. In addition, hypoxia in adipose tissue as a direct consequence of obesity, and its effect on gene expression in adipocytes and surrounding cells in fat tissue of obese subjects appears to play a central role in this inflammatory response too. In contrast, revisiting diet all over the world, there are also some natural food products and beverages which are associated with curative effects on human health. Several natural compounds known as spices such as curcumin, capsaicin, and gingerol, or secondary plant metabolites catechin, resveratrol, genistein, and quercetin have been reported to provide an improved health status to their consumers, especially with regard to diabetes, and therefore have been investigated for their anti-inflammatory effect. In this review, we will give an overview about these phytochemicals and their role to interfere with inflammatory cascades in adipose tissue and their potential for fighting against inflammatory diseases like diabetes as investigated in vivo.

Effect of Resveratrol on NF-κB Activity in Rat Peritoneal Macrophages

This study was to investigate the inhibitive effect of resveratrol (RESV) on nuclear factor kappa B (NF-κB) expression and activity induced by lipopolysaccharide (LPS) in rat peritoneal macrophages (PMA). Male Sprague-Dawley (SD) rats were randomly divided into 7 groups, including control group, LPS group and RESV I-V group. In the LPS group, PMA were incubated in DMEM containing LPS (10 μg/ml), whereas in control group, PMA were incubated in DMEM only. In the RESV I-V groups, PMA were incubated in DMEM containing LPS (10 μg/ml) and different concentrations of RESV. After 24 hours of incubation, NF-κB activity in PMA, and the levels of tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1) and nitric oxide (NO) in the culture medium were measured. In the concentrations of 1.25-5 μg/ml, RESV had a dose- dependent inhibitive effect on NF-κB activity in PMA as well as the expressions of TNF-α, IL-1 and NO in the culture medium contrasted with the LPS group. There was no significant difference in the levels of these pro-inflammatory factors between the groups of 5 μg/ml and 10 μg/ml RESV. In conclusion, RESV has the potential for the future application of preventing inflammatory diseases involving PMA.

Resveratrol down-regulates interferon-γ-inducible inflammatory genes in macrophages: molecular mechanism via decreased STAT-1 activation

Resveratrol (trans-3,4',5-trihydroxystilbene) is one of nonflavonoid polyphenolic phytoalexins found in various plant species, a number of which are components of human diet including grapes and red wines. Resveratrol has exerted several beneficial effects with anti-inflammation, cardioprotection and cancer chemoprevention. However, its mechanisms of action are not completely understood. In this study, we investigated effects of resveratrol on inflammatory gene expression in interferon (IFN)-γ alone-stimulated macrophages and proposed a molecular basis underlying the action. Resveratrol inhibited IFN-γ-induced production of nitric oxide (NO), IFN-γ-inducible protein-10 (IP-10), or the monokine induced by IFN-γ (MIG) in RAW 264.7 macrophages and also that of NO in primary macrophages derived from bone marrows of C3H/HeJ (toll-like receptor-4(-/-)) mice. Moreover, resveratrol diminished IFN-γ-induced protein levels of inducible NO synthase (iNOS), attenuated mRNA levels of iNOS, IP-10 or MIG as well as inhibited IFN-γ-induced promoter activity of iNOS gene, indicating that the phytoalexin could down-regulate inflammatory genes at the transcription level. To understand a mechanism of the action, we tested resveratrol could affect the signal transducers and activation of transcription-1 (STAT-1), a pivotal transcription factor in IFN-γ-induced expression of inflammatory genes. Resveratrol inhibited IFN-γ-induced transcriptional activity of STAT-1 in macrophages and also IFN-γ-induced Tyr(701) or Ser(727) phosphorylation of STAT-1. We then focused on protein kinases upstream STAT-1 phosphorylation. Resveratrol inhibited IFN-γ-induced activation of Janus kinase-2 (JAK-2) and also the extracellular signal-regulated kinase, in which JAK-2 was more sensitive. Taken together, this study proposes a new mechanism of resveratrol, blocking JAK/STAT-1 pathway that controls inflammatory responses in IFN-γ-activated macrophages.

Effect of resveratrol and quercetin in experimental infection by Salmonella enterica serovar Typhimurium

Flavonoids are phenolic compounds widely distributed in almost every plant and act as pharmacologically active constituents in many herbal medicines. They have multiple biological, pharmacological, and medicinal properties including anti-inflammatory and cytoprotective effects. In the present study, the experiments were performed to evaluate the effect of resveratrol and quercetin on proliferation, viability, nitric oxide (NO) production, and apoptosis in Salmonella enterica serovar Typhimurium-infected U937 cells and monocytes (MN). The results showed in a time- and dose-dependent manner that both resveratrol and quercetin reduced S. enterica serovar Typhimurium-induced NO production. In addition, the vegetable extracts resveratrol and quercetin inhibited cell viability and proliferation in S. enterica serovar Typhimurium-infected cells. S. enterica serovar Typhimurium-induced apoptosis was also blocked by resveratrol and quercetin. The results obtained indicate that flavonoids modulate the host response during salmonellosis by protecting the host cells from the toxic effects of bacterial infection and also by decreasing programmed cell death. Hence, these polyphenols can be considered potential candidates against S. enterica serovar Typhimurium-related gastric pathogenic processes, and further attention should be given to their application as a treatment for infectious diseases.

Salicylideneamino-2-thiophenol inhibits inflammatory mediator genes (RANTES, MCP-1, IL-8 and HIF-1alpha) expression induced by tert-butyl hydroperoxide via MAPK pathways in rat peritoneal macrophages

Salicylideneamino-2-thiophenol (Sal) regulated the redox status and the expression of chemokines induced by tert-butyl hydroperoxide (t-BHP). Sal (100 microM) increased reduced/oxidized glutathione (GSH/GSSG) ratios and thiol (SH) levels by 210 and 157%, respectively, and decreased reactive oxygen species (ROS) levels by 60% in t-BHP-treated macrophages. The inductions of regulated upon activation, normal T-cell expressed and secreted (RANTES), monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8) and hypoxia inducible factor-1alpha (HIF-1alpha) by t-BHP (10 microM) were decreased to 250, 80, 80 and 500% by Sal (100 microM), respectively. In the Sal signaling pathway, c-Jun N-terminal kinases (JNK), extracellular signal-regulated kinases (ERK) and p38 signaling protein modulation were decreased by 67, 69 and 119%, respectively, by Sal at 100 microM. Sal (100 microM) also altered cytosol and nuclear NF-kappaB protein expression by 169 and 5%, respectively. Sal also attenuated NF-kappaB nuclear binding activity. Sal thus has a protective effect against t-BHP-induced inflammation and that this, in part, is due to the inhibition of the production of RANTES, MCP-1, IL-8 and HIF-1alpha via the modulation of the NF-kappaB and mitogen-activated protein kinase (MAPK) pathways.

Resveratrol attenuates inflammation and stricture formation in experimental caustic esophageal burns

The purpose of medical treatment in the caustic esophageal burns (CEB) is to decrease inflammatory reaction and to prevent stricture formation. Resveratrol has anti-inflammatory and antifibrotic properties. The aim of this study is to investigate potential therapeutic effects of resveratrol in experimental CEB. We divided 42 male Wistar albino rats into five groups: a control group, caustic groups 4 and 28 (esophageal burns were created), and resveratrol groups 4 and 28 (esophageal burns were created and resveratrol was administered). We used 25% NaOH to form CEB following the method of Gehanno and Guedon as modified by Liu and Richardson. Animals were killed on the 4th and 28th days for biochemical and histopathological examinations. We found that the mean malondialdehyde and nitric oxide assays of the caustic groups were significantly higher than that of the resveratrol groups (P < 0.05). On the other hand, glutathione assay of the resveratrol groups was significantly higher than that of the caustic groups (P < 0.05). Histologically, edema, inflammation and necrosis were found to be significantly lower in the resveratrol 4 group compared with the caustic 4 group (P < 0.05). Submucosal and muscular collagen accumulation were found significantly lower in the resveratrol 28 group compared with the caustic 28 group (P < 0.05). We conclude that resveratrol decreased both the inflammatory reaction and the stricture formation in experimental CEB.

Resveratrol as an antioxidant and pro-oxidant agent: mechanisms and clinical implications

Resveratrol (3,4',5-trihydroxystilbene) is found in various plants, including grapes, berries and peanuts. It is also present in wines, especially red wines. During the last years, it has been the focus of numerous in vitro and in vivo studies investigating its biological attributes, which include mainly antioxidant and anti-inflammatory activities, anti-platelet aggregation effect, anti-atherogenic property, oestrogen-like growth-promoting effect, growth-inhibiting activity, immunomodulation and chemoprevention. In fact, recently, it has been demonstrated that the stilbene blocks the multistep process of carcinogenesis at various stages: tumour initiation, promotion and progression. More recent results provide interesting insights into the effect of this compound on the life span of yeasts and flies, implicating the potential of resveratrol as an anti-aging agent in treating age-related human diseases. Nevertheless, depending on the concentration of the phytoalexin and the cell type, it has also been shown that resveratrol can exhibit pro-oxidant properties, leading to oxidative breakage of cellular DNA in the presence of transition metal ions such as copper. Recently, it has been proposed that such a pro-oxidant action could be a common mechanism for anticancer and chemopreventive properties of plant polyphenols. The present paper is intended to provide the reader up-to-date information on the antioxidant and pro-oxidant properties of resveratrol and its clinical implications.

Resveratrol modulates phagocytosis of bacteria through an NF-kappaB-dependent gene program

Many studies have shown that the pharmacological effects of resveratrol, a phytoalexin polyphenolic compound, include protective effects against cancer and inflammation as well as enhancement of stress resistance. In this study, we examined whether resveratrol affected the phagocytosis of bacteria by macrophages and the activation of the transcription factor NF-kappaB after stimulation with or without the ligand FSL-1 for Toll-like receptor 2 (TLR2). Phagocytosis of Escherichia coli and of Staphylococcus aureus by THP-1 cells and RAW264.7 cells was inhibited by resveratrol in a dose-dependent manner regardless of stimulation with FSL-1. The NF-kappaB activity in HEK293 cells stably expressing TLR2 was also inhibited by resveratrol after stimulation with FSL-1. Resveratrol also inhibited both the translocation of p65 of NF-kappaB into nuclei in the transfectant and tumor necrosis factor alpha production by THP-1 cells or RAW264.7 cells. It has recently been reported that TLR-mediated signaling pathways lead to the upregulation of mRNAs of phagocytic receptors, including scavenger receptors and C-type lectin receptors. This study also demonstrated that FSL-1 induced the upregulation of mRNAs of phagocytic receptors such as macrophage scavenger receptor-1, CD36, DC-SIGN, and Dectin-1 and that the FSL-1-induced upregulation of their mRNAs was inhibited by resveratrol. In addition, it was found that the expression of DC-SIGN in HEK293 cells stably expressing DC-SIGN was reduced by resveratrol and that the phagocytic activity was significantly inhibited by resveratrol. Thus, this study suggests that resveratrol inhibited bacterial phagocytosis by macrophages by downregulating the expression of phagocytic receptors and NF-kappaB activity.

Immunomodulating activities of acidic sulphated polysaccharides obtained from the seaweed Ulva rigida C. Agardh

Water-soluble acidic polysaccharides from the cell walls of Ulva rigida are mainly composed of disaccharides that contain glucuronic acid and sulphated rhamnose. The structure of disaccharides resembles that of glycosaminoglycans (GAGs) as they both contain glucuronic acid and sulphated sugars. Glycosaminoglycans occur in the extracellular matrix of animal connective tissues but can also be produced by leucocytes at inflammatory sites. Certain types of GAGs can even activate macrophages and therefore the acidic polysaccharides from U. rigida probably modulate macrophage activity. In the present study, we evaluated the effects of U. rigida polysaccharides on several RAW264.7 murine macrophage activities, including expression of inflammatory cytokines and receptors, nitric oxide and prostaglandin E2 (PGE(2)) production, and nitric oxide synthase 2 (NOS-2) and cyclooxygenase-2 (COX-2) gene expression. U. rigida acidic polysaccharides induced a more than two-fold increase in the expression of several chemokines (chemokine (C motif) ligand 1, chemokine (C-X-C motif) ligand 12, chemokine (C-C motif) ligand 22 and chemokine (C-X-C motif) ligand 14 (Cxcl14)) and in the expression of IL6 signal transducer and IL12 receptor beta 1. Incubation of macrophages with U. rigida polysaccharides also induced an increase in nitrite production, although this effect decreased considerably after desulphation of polysaccharides, suggesting that the sulphate group is important for the stimulatory capacity of these molecules. U. rigida polysaccharides also stimulated macrophage secretion of PGE(2) and induced an increase in COX-2 and NOS-2 expression. The results indicate that U. rigida acid polysaccharide can be used as an experimental immunostimulant for analysing inflammatory responses related to macrophage functions. In addition, these polysaccharides may also be of clinical interest for modifying certain macrophage activities in diseases where macrophage function is impaired or needs to be boosted.

Resveratrol, a red wine polyphenol, attenuates ethanol-induced oxidative stress in rat liver

The involvement of oxidative stress in the pathogenesis of alcoholic diseases in the liver has been repeatedly confirmed. Resveratrol, a natural phytoalexin present in grape skin and red wine possesses a variety of biological activities including antioxidant. This study was conducted to evaluate whether resveratrol has a preventive effect on the main indicators of hepatic oxidative status as an expression of the cellular damage caused by free radicals, and on antioxidant defence mechanism during chronic ethanol treatment. Wistar rats were treated daily with 35% ethanol solution (3 g/kg/day i.p.) during 6 weeks and fed basal diet or basal diet containing 5 g/kg resveratrol. Control rats were treated with i.p. saline and fed basal diet. Experimentally, chronic ethanol administration leads to hepatotoxicity as monitored by the increase in the level of hepatic marker enzymes and the appearance of fatty change, necrosis, fibrosis and inflammation in liver sections. Ethanol also enhanced the formation of MDA in the liver indicating an increase in lipid peroxidation, a major end-point of oxidative damage, and caused drastic alterations in antioxidant defence systems. Particularly the activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were found reduced by ethanol treatment while glutathione reductase (GR) activity was unchanged. Dietary supplementation with resveratrol during ethanol treatment inhibited hepatic lipid peroxidation and ameliorated SOD, GPx and CAT activities in the liver. Conclusively, we can suggest that resveratrol could have a beneficial effect in inhibiting the oxidative damage induced by chronic ethanol administration, which was proved by the experiments that we conducted on rats.

Resveratrol inhibits insulin secretion from rat pancreatic islets

Resveratrol is a naturally occurring phytoalexin exerting cardioprotective, anticancer and antioxidant action. The most recent investigations have demonstrated that this compound plays a beneficial role alleviating some diabetic complications. However, resveratrols' influence on the endocrine function of the pancreas is unknown. The objective of the present study was to determine whether resveratrol affects insulin secretion from freshly isolated rat pancreatic islets. Incubations of pancreatic islets with resveratrol (1-100 microM, 90 min) revealed that the release of insulin induced by 6.6 and 16.6 mM glucose was substantially restricted by this compound in a concentration-dependent manner. This effect was not permanent and disappeared after resveratrol withdrawal from the buffer. However, the proper hormone secretion was not restored when glucose was replaced by other secretagogues - leucine with glutamine - indicating that disturbances other than the inhibition of glucose transport and glycolysis were responsible for the resveratrol-evoked reduction in insulin secretion. Glucose-induced insulin release tested in the presence of the sulfonylurea glibenclamide was also found to be reduced by resveratrol. Moreover, the activation of adenylyl cyclase by forskolin did not restrict the inhibitory effect of resveratrol on glucose-induced insulin release. In contrast, phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, suppressed completely the inhibitory effect of 1 and 10 microM resveratrol on insulin release. However, this compound at the highest concentration tested diminished its secretion even in the presence of PMA. The perifusion studies revealed that the depression of insulin release caused by resveratrol began a few minutes after its addition to the medium. Results obtained in the present investigations demonstrate that resveratrol is a compound exerting a clear-cut, but reversible inhibitory effect on insulin secretion from isolated pancreatic islets.

Resveratrol as an anti-inflammatory and anti-aging agent: mechanisms and clinical implications

Resveratrol is a phytoalexin polyphenolic compound found in various plants, including grapes, berries, and peanuts. Multiple lines of compelling evidence indicate its beneficial effects on neurological, hepatic, and cardiovascular systems. Also one of the most striking biological activities of resveratrol soundly investigated during the late years has been its cancer-chemopreventive potential. In fact, recently it has been demonstrated that this stilbene blocks the multistep process of carcinogenesis at various stages: tumor initiation, promotion, and progression. One of the possible mechanisms for its biological activities involves downregulation of the inflammatory response through inhibition of synthesis and release of pro-inflammatory mediators, modification of eicosanoid synthesis, inhibition of activated immune cells, or inhibiting such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) via its inhibitory effects on nuclear factor (kappa)B (NF-(kappa)B) or the activator protein-1 (AP-1). More recent data provide interesting insights into the effect of this compound on the lifespan of yeast and flies, implicating the potential of resveratrol as an anti-aging agent in treating age-related human diseases. It is worthy to note that the phenolic compound possesses a low bioavailability and rapid clearance from the plasma. As the positive effects of resveratrol on inflammatory response regulation may comprise relevant clinical implications, the purpose of this article is to review its strong anti-inflammatory activity and the plausible mechanisms of these effects. Also, this review is intended to provide the reader an up-date of the bioavailability and pharmacokinetics of resveratrol and its impact on lifespan.

Effect of cis-resveratrol on genes involved in nuclear factor kappa B signaling

This study investigated for the first time the effects of the cis isomer of RESV (c-RESV), a polyphenol present in red wine, on an array of genes whose expression is controlled by nuclear factor kappa B (NF-kappaB) and whose transcriptional activation is critical in a number of pathologies (including some cardiovascular diseases). In inflammatory peritoneal macrophages stimulated with lipopolysaccharide (LPS) and gamma interferon (IFN-gamma), c-RESV significantly blocked the expression of genes related to the REL/NF-kappaB/IkappaB family, adhesion molecules and acute-phase proteins; however, the greatest modulatory effect was obtained on the expression of genes related to the pro-inflammatory cytokines. c-RESV down-regulated the nuclear factor of kappa light chain gene enhancer in B-cells 1 (NFkappaBL1) gene product p105 and up-regulated the nuclear factor of kappa light chain gene enhancer in B-cells inhibitor alpha (IkappaBalpha) gene. c-RESV also significantly inhibited intercellular adhesion molecule-1 (ICAM-1) gene expression and the transmembrane receptors RIP (receptor TNFRSF) and TLR3 (toll-like receptor 7). At 100 muM, c-RESV significantly inhibited transcription of Scya2 (chemokine MCP-1), the chemokine RANTES (regulated on activation, normal T cell expressed and secreted), pro-inflammatory cytokines that attract monocyte-granulocyte cells such as M-CSF (colony-stimulating factor 1), GM-CSF (colony-stimulating factor 2) and G-CSF (colony-stimulating factor 3), the cytokine tumor growth factor beta (TGF-beta) and the extracellular ligand IL-1alpha. In contrast, c-RESV stimulated transcription of the pro-inflammatory cytokines IL-6 and tumor necrosis factor alpha (TNF-alpha), the extracellular ligand IL-1beta, and the IFN regulatory factor (IRF)-1. In conclusion, c-RESV has a significant modulatory effect on the NF-kappaB signaling pathway and, consequently, an important antioxidant role that may partially explain the cardioprotective effects attributed to long-term moderate red wine consumption.

Expression profiles of genes involved in the mouse nuclear factor-kappa B signal transduction pathway are modulated by mangiferin

The polyphenol mangiferin (MA) has been shown to have various effects on macrophage function, including inhibition of phagocytic activity and of free radical production. To further characterize the immunomodulatory activity of MA, this study investigated its effects on expression by activated mouse macrophages of diverse genes related to the NF-kappaB signaling pathway, using a DNA hybridization array containing 96 NF-kappaB-related genes and on cytokine levels using a cytokine protein array. MA at 10 microM significantly inhibited the expression of (a) two genes of the Rel/NF-kappaB/IkappaB family, RelA and RelB (=I-rel), indicating an inhibitory effect on NF-kappaB-mediated signal transduction; (b) TNF receptor-associated factor 6 (Traf6), indicating probable blockage of activation of the NF-kappaB pathway by lipopolysaccharide (LPS), tumor necrosis factor (TNF), and interleukin 1 (IL-1); (c) other proteins involved in responses to TNF and in apoptotic pathways triggered by DNA damage, including the TNF receptor (TNF-R), the TNF-receptor-associated death domain (TRADD), and the receptor interacting protein (RIP); (d) the extracellular ligand IL-1alpha, again indicating likely interference with responses to IL-1; (e) the pro-inflammatory cytokines IL-1, IL-6, IL-12, TNF-alpha and RANTES (CCL5), and cytokines produced by monocytes and macrophages, including granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF); (f) other toll-like receptor proteins (in addition to Traf6), including JNK1, JNK2 and Tab1; (g) Scya2 (small inducible cytokine A2=monocyte chemoattractant protein 1); and (h) various intracellular adhesion molecules (ICAMs), and the vascular cell adhesion molecule VCAM-1, which is locally increased in atheromas. The inhibition of JNK1, together with stimulation of c-JUN (i.e. the Jun oncogene) and the previously reported superoxide-scavenging activity of MA, suggests that MA may protect cells against oxidative damage and mutagenesis. Taken together, these results indicate that MA modulates the expression of a large number of genes that are critical for the regulation of apoptosis, viral replication, tumorogenesis, inflammation and various autoimmune diseases, and raise the possibility that it may be of value in the treatment of inflammatory diseases and/or cancer.

Effects of cis-resveratrol on inflammatory murine macrophages: antioxidant activity and down-regulation of inflammatory genes

This study investigated for the first time the effects of the cis isomer of resveratrol (c-RESV) on the responses of inflammatory murine peritoneal macrophages, namely on the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) during the respiratory burst; on the biosynthesis of other mediators of inflammation such prostaglandins; and on the expression of inflammatory genes such as inducible nitric oxide synthase (NOS)-2 and inducible cyclooxygenase (COX)-2. Treatment with 1-100 microM c-RESV significantly inhibited intracellular and extracellular ROS production, and c-RESV at 10-100 microM significantly reduced RNS production. c-RESV at 1-100 microM was ineffective for scavenging superoxide radicals (O(2)(.-)), generated enzymatically by a hypoxanthine (HX)/xanthine oxidase (XO) system and/or for inhibiting XO activity. However, c-RESV at 10-100 microM decreased nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NADH/NADPH) oxidase activity in macrophage homogenates. c-RESV at 100 microM decreased NOS-2 and COX-2 mRNA levels in lipopolysaccharide (LPS) interferon gamma (IFN-gamma)-treated macrophages. At 10-100 microM, c-RESV also significantly inhibited NOS-2 and COX-2 protein synthesis and decreased prostaglandin E(2) (PGE(2)) production. These results indicate that c-RESV at micromolar concentrations significantly attenuates several components of the macrophage response to proinflammatory stimuli (notably, production of O(2)(.-)(-) and of the proinflammatory mediators NO(.-) and PGE(2)).

Antioxidant activity and inhibitory effects of hydralazine on inducible NOS/COX-2 gene and protein expression in rat peritoneal macrophages

This study investigated the effects of the peripheral vasodilator hydralazine on in vitro generation of reactive species of oxygen (ROS), nitrogen (RNS) and prostaglandin (PG) biosynthesis in elicited murine peritoneal macrophages, and on the gene expression and protein synthesis of two key enzymes in the inflammatory process, inducible NO(*) synthase (NOS-2) and inducible cyclooxygenase 2 (COX-2). Hydralazine at 0.1-10 mM inhibited both extracellular and intracellular ROS production by inflammatory macrophages, by a ROS-scavenging mechanism probably affecting superoxide radical (O(2)(*-))-generation by xanthine oxidase (XO) and nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NADH/NADPH) oxidase. Hydralazine at 0.1-10 mM significantly reduced NO(*) generation, and this effect was attributable to an inhibition of NOS-2 gene expression and protein synthesis. At 1-10 mM, hydralazine also effectively blocked COX-2 gene expression which perfectly correlated with a reduction of protein levels and PGE(2) synthesis. These data suggest that hydralazine, at the concentrations tested, show antioxidant properties and strongly attenuates the macrophage activation.

In vitro effects of mangiferin on superoxide concentrations and expression of the inducible nitric oxide synthase, tumour necrosis factor-alpha and transforming growth factor-beta genes

This study investigated the effects of the natural polyphenol mangiferin (MA) on superoxide anion (O(2)(-)) production, xanthine oxidase (XO) activity, vascular contractility, inducible nitric oxide synthase (iNOS) mRNA levels, tumour necrosis factor-alpha (TNF-alpha) mRNA levels, and tumour growth factor-beta (TGF-beta) mRNA levels. O(2)(-) was generated by the hypoxanthine-xanthine oxidase (HX-XO) and phenazine methosulphate (PMS)-NADH systems. XO activity was determined by measurement of uric acid production with xanthine as substrate. Vascular contraction experiments were performed with intact rat aortic rings. iNOS, TNF-alpha and TGF-beta gene expression in rat macrophages stimulated in vivo with 3% thioglycollate and in vitro with 100 ng/mL lipopolysaccharide and 10U/mL of interferon-gamma were evaluated semiquantitatively by the retrotranscriptase-polymerase chain reaction. MA at 10-100 microM, like the known O(2)(-) scavenger superoxide dismutase (1U/mL), scavenged O(2)(-) produced by the HX/XO and PMS-NADH systems. By contrast MA at 1-100 microM, unlike allopurinol (10 microM), was unable to inhibit XO activity. MA at 1-100 microM did not modify resting tone or the contractile responses elicited by 1 microM phenylephrine or 1 microM phorbol 12-myristate 13-acetate in rat aorta. MA at 1-100 microM, like dexamethasone (100 microM), decreased iNOS mRNA levels in activated macrophages. At 100 microM, MA also reduced TNF-alpha mRNA levels, but increased TGF-beta mRNA levels. These results thus indicate that MA is an O(2)(-) scavenger and that it inhibits expression of the iNOS and TNF-alpha genes, suggesting that it may be of potential value in the treatment of inflammatory and/or neurodegenerative disorders. In addition, the finding that MA enhances TGF-beta gene expression suggests that this polyphenol might also be of value in the prevention of cancer, autoimmune disorders, atherosclerosis and coronary heart disease.