The cancer chemopreventive agent resveratrol is incorporated into model membranes and inhibits protein kinase C alpha activity

Trans-Resveratrol Decreases Membrane Water Permeability: A Study of Cholesterol-Dependent Interactions

Resveratrol (RSV), a biologically active plant phenol, has been extensively investigated for cancer prevention and treatment due to its ability to regulate intracellular targets and signaling pathways which affect cell growth and metastasis. The non-specific interactions between RSV and cell membranes can modulate physical properties of membranes, which in turn can affect the conformation of proteins and perturb membrane-hosted biological functions. This study examines non-specific interactions of RSV with model membranes having varying concentrations of cholesterol (Chol), mimicking normal and cancerous cells. The perturbation of the model membrane by RSV is sensed by changes in water permeability parameters, using Droplet Interface Bilayer (DIB) models, thermotropic properties from Differential Scanning Calorimetry, and structural properties from confocal Raman spectroscopy, all of which are techniques not complicated by the use of probes which may themselves perturb the membrane. The nature and extent of interactions greatly depend on the presence and absence of Chol as well as the concentration of RSV. Our results indicate that the presence of RSV decreases water permeability of lipid membranes composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), indicating a capability for RSV in stiffening fluidic membranes. When Chol is present, however, (at 4:1 and 2:1 mol ratio DOPC to cholesterol), the addition of RSV has no significant effect upon the water permeability. DSC thermograms show that RSV interacts with DOPC and DOPC/Chol bilayers and influences their thermotropic phase behavior in a concentration-dependent manner, by decreasing the main phase transition temperature and enthalpy, with a phase separation shown at the higher concentrations of RSV. Raman spectroscopic studies indicate an ordering effect of RSV on DOPC supported bilayer, with a lesser extent of ordering in the presence of Chol. Combined results from these investigations highlight a differential effect of RSV on Chol-free and Chol-enriched membranes, respectively, which results constitute a bellwether for increased understanding and effective use of resveratrol in disease therapy including cancer.

Anti-Inflammatory Action and Mechanisms of Resveratrol

Resveratrol (3,4',5-trihy- droxystilbene), a natural phytoalexin polyphenol, exhibits anti-oxidant, anti-inflammatory, and anti-carcinogenic properties. This phytoalexin is well-absorbed and rapidly and extensively metabolized in the body. Inflammation is an adaptive response, which could be triggered by various danger signals, such as invasion by microorganisms or tissue injury. In this review, the anti-inflammatory activity and the mechanism of resveratrol modulates the inflammatory response are examined. Multiple experimental studies that illustrate regulatory mechanisms and the immunomodulatory function of resveratrol both in vivo and in vitro. The data acquired from those studies are discussed.

Resveratrol-Loaded Lipid Nanocarriers Are Internalized By Endocytosis in Yeast

Different positive pharmacological effects have been attributed to the natural product resveratrol (RSV), including antioxidant, antiaging, and cancer chemopreventive properties. However, its low bioavailability and rapid metabolic degradation has led to the suspicion that many of the biological activities of this compound observed in vitro may not be attainable in humans. To improve its bioavailability and pharmacokinetic profile, attempts have been made to encapsulate RSV into lipid-based nanocarrier systems. Here, the dioctadecyldimethylammonium bromide (DODAB):monoolein (MO) liposomal system (1:2) loaded with RSV revealed appropriate characteristics for drug release purposes: reduced size for cellular uptake (157 ± 23 nm), stability up to 80 days, positive surface charge (ζ ≈ +40 mV), and a controlled biphasic release of RSV from the lipid nanocarriers over a period of almost 50 h at pH 5.0 and 7.4. Moreover, the encapsulation efficiency of the nanocarrier ranged from 70% to 92% and its RSV loading capacity from 9% to 14%, when [RSV] was between 100 and 200 μM. The partition coefficient ( K_p) of RSV between lipid and aqueous phase was log K_p = 3.37 ± 0.10, suggesting moderate to high lipophilicity of this natural compound and reinforcing the lipid nanocarriers' suitability for RSV incorporation. The thermodynamic parameters of RSV partitioning in the lipid nanocarriers at 37 °C (Δ H = 43.76 ± 5.68 kJ mol^-1; Δ S = 0.20 ± 0.005 kJ mol^-1; and Δ G = -18.46 ± 3.48 kJ mol^-1) reflected the spontaneity of the process and the establishment of hydrophobic interactions. The cellular uptake mechanism of the RSV-loaded nanocarriers labeled with the lipophilic fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) was studied in the eukaryotic model system Saccharomyces cerevisiae. Thirty minutes after incubation, yeast cells readily internalized nanocarriers and the spots of blue fluorescence of DPH clustered around the central vacuole in lipid droplets colocalized with the green fluorescence of the lipophilic endocytosis probe FM1-43. Subsequent studies with the endocytosis defective yeast deletion mutant ( end3Δ) and with the endocytosis inhibitor methyl-β-cyclodextrin supported the involvement of an endocytic pathway. This novel nanotechnology approach opens good perspectives for medical applications.

The Effect of Resveratrol on the Composition and State of Lipids and the Activity of Phospholipase A2 During the Excitation and Regeneration of Somatic Nerves

It has been shown that in the somatic nerve's lipids, both during excitation and transection, changes occur with the composition of individual phospholipids and in phospholipids fatty acids, which changes the phase state of the myelin and nerve fiber axolemma lipid bilayer. A main contribution in the nerve degenerative processes is dependent on the composition phospholipid's fatty acid changes during the activation of both Ca²⁺-dependent and Ca²⁺-independent phospholipase A₂ forms. At the same time, we studded changes in phosphoinisitol (PI) and diacylglycerol (DAG), which depend on the phosphoinositide cycle function during nerve excitation and degeneration processes. It was found that myelin lipids and nerve fiber axolemmas are involved not only in the functioning of the peripheral nerves, but also the pathological processes underlying deep functional and structural disorders. The effect of resveratrol on regeneration processes in the damaged rat sciatic nerve has also been investigated.

Influence of resveratrol on interactions between negatively charged DPPC/DPPG membranes and positively charged poly-l-lysine

Resveratrol (Res), a natural polyphenol present in different plants and vegetables, exhibits potential therapeutic activity with cardioprotective, antineurodegenerative, antioxidant, and antitumor action. In this study, the effect of Res on the mutual interactions between positively charged poly-l-lysine (PLL) and negatively charged dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylglycerol (DPPC/DPPG) membranes was studied using Fourier-transform infrared (FTIR) spectroscopy supported by principal component analysis (PCA). The interactions between PLL and DPPC/DPPG membranes were strongly affected by the presence of Res molecules. Depending on the Res concentration and method of its supply (through the water or lipid phase) to the studied peptide-membrane systems, the membrane-induced transition of PLL from an α-helix to an extended left-handed polyproline II helix (PPII) occurred at different temperatures, with different cooperativity, or was even completely suppressed. The influence of PLL on the conformational (trans/gauche) state of the hydrocarbon chain region of the lipid membranes and the hydration state of the polar/apolar membrane interface was also modulated by Res, depending on the membrane phase state.

Ellagitannin HeT obtained from strawberry leaves is oxidized by bacterial membranes and inhibits the respiratory chain

Plant secondary metabolism produces a variety of tannins that have a wide range of biological activities, including activation of plant defenses and antimicrobial, anti‐inflammatory and antitumoral effects. The ellagitannin HeT (1‐O‐galloyl‐2,3;4,6‐bis‐hexahydroxydiphenoyl‐β‐d‐glucopyranose) from strawberry leaves elicits a strong plant defense response, and exhibits antimicrobial activity associated to the inhibition of the oxygen consumption, but its mechanism of action is unknown. In this paper we investigate the influence of HeT on bacterial cell membrane integrity and its effect on respiration. A β‐galactosidase unmasking experiment showed that HeT does not disrupt membrane integrity. Raman spectroscopy analysis revealed that HeT strongly interacts with the cell membrane. Spectrochemical analysis indicated that HeT is oxidized in contact with bacterial cell membranes, and functional studies showed that HeT inhibits oxygen consumption, NADH and MTT reduction. These results provide evidence that HeT inhibits the respiratory chain.

Resveratrol Inhibition of Cellular Respiration: New Paradigm for an Old Mechanism

Resveratrol (3,4′,5-trihydroxy-trans-stilbene, RSV) has emerged as an important molecule in the biomedical area. This is due to its antioxidant and health benefits exerted in mammals. Nonetheless, early studies have also demonstrated its toxic properties toward plant-pathogenic fungi of this phytochemical. Both effects appear to be opposed and caused by different molecular mechanisms. However, the inhibition of cellular respiration is a hypothesis that might explain both toxic and beneficial properties of resveratrol, since this phytochemical: (1) decreases the production of energy of plant-pathogenic organisms, which prevents their proliferation; (2) increases adenosine monophosphate/adenosine diphosphate (AMP/ADP) ratio that can lead to AMP protein kinase (AMPK) activation, which is related to its health effects, and (3) increases the reactive oxygen species generation by the inhibition of electron transport. This pro-oxidant effect induces expression of antioxidant enzymes as a mechanism to counteract oxidative stress. In this review, evidence is discussed that supports the hypothesis that cellular respiration is the main target of resveratrol.

Effects of resveratrol on the structure and fluidity of lipid bilayers: a membrane biophysical study

Resveratrol is a natural active compound which has been attracting increasing interest due to its several pharmacological effects in cancer prevention, cardiovascular protection and treatment of neurodegenerative disorders and diabetes. The current work investigates how resveratrol affects membrane order and structure, gathering information determined by X-ray scattering analysis, derivative spectrophotometry, fluorescence quenching and fluorescence anisotropy studies. The results indicate that resveratrol is able to be incorporated into DMPC liposome model systems, either fluidizing or stiffening the bilayer, which largely depends on the membrane fluidity state. These findings suggest that the effects of resveratrol resemble cholesterol action on biological membranes, thereby contributing to the regulation of cell membrane structure and fluidity, which may influence the activity of transmembrane proteins and hence control the cell signaling pathways. The regulation of a number of cellular functions, thus may contribute to the pharmacological and therapeutic activities of this compound, explaining its pleiotropic action.

Capsaicin Fluidifies the Membrane and Localizes Itself near the Lipid-Water Interface

Capsaicin is the chemical responsible for making some peppers spicy hot, but additionally it is used as a pharmaceutical to alleviate different pain conditions. Capsaicin binds to the vanilloid receptor TRPV1, which plays a role in coordinating chemical and physical painful stimuli. A number of reports have also shown that capsaicin inserts in membranes and its capacity to modify them may be part of its molecular mode of action, affecting the activity of other membrane proteins. We have used differential scanning calorimetry, X-ray diffraction, (31)P NMR, and (2)H NMR spectroscopy to show that capsaicin increases the fluidity and disorder of 1,2-palmitoyl-sn-glycero-3-phosphocholine membrane models. By using (1)H NOESY MAS NMR based on proton-proton cross-peaks between capsaicin and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine resonances, we determined the location profile of this molecule in a fluid membrane concluding that it occupies the upper part of the phospholipid monolayer, between the lipid-water interface and the double bond of the acyl chain in position sn-2. This location explains the disorganization of the membrane of both the lipid-water interface and the hydrophobic palisade.

New Insights on the Biophysical Interaction of Resveratrol with Biomembrane Models: Relevance for Its Biological Effects

Resveratrol has been widely studied because of its pleiotropic effects in cancer therapy, neuroprotection, and cardioprotection. It is believed that the interaction of resveratrol with biological membranes may play a key role in its therapeutic activity. The capacity of resveratrol to partition into lipid bilayers, its possible location within the membrane, and the influence of this compound on the membrane fluidity were investigated using membrane mimetic systems composed of egg l-α-phosphatidylcholine (EPC), cholesterol (CHOL), and sphingomyelin (SM). The results showed that resveratrol has greater affinity for the EPC bilayers than for EPC:CHOL [4:1] and EPC:CHOL:SM [1:1:1] membrane models. The increased difficulty in penetrating tight packed membranes is also demonstrated by fluorescence quenching of probes and by fluorescence anisotropy measurements. Resveratrol may be involved in the regulation of cell membrane fluidity, thereby contributing for cell homeostasis.

Polyphenols and the modulation of gene expression pathways: can we eat our way out of the danger of chronic disease?

Plant-derived dietary polyphenols may improve some disease states and promote health. Experimental evidence suggests that this is partially attributable to changes in gene expression. The rational use of bioactive food components may therefore present an opportunity to activate or repress selected gene expression pathways and, consequently, to manage or prevent disease. It remains to be determined whether this use of bioactive food components can be done safely. This article reviews the associated controversies and limitations of polyphenol therapy. There is a paucity of clinical data on the rational use of polyphenols, including a lack of knowledge on effective dosage, actual chemical formulations, bioavailability, distribution in tissues, the effect of genetic variations, differences in gut microflora, the synergistic (or antagonistic) effects observed in extracts, and the possible interaction between polyphenols and lipid domains of cell membranes that may alter the function of relevant receptors. The seminal question of why plants make substances that benefit humans remains unanswered, and there is still much to learn in terms of correlative versus causal effects of human exposure to various nutrients. The available data strongly suggest significant effects at the molecular level that represent interactions with the epigenome. The advent of relatively simple technologies is helping the field of epigenetics progress and facilitating the acquisition of multiple types of data that were previously difficult to obtain. In this review, we summarize the molecular basis of the epigenetic regulation of gene expression and the epigenetic changes associated with the consumption of polyphenols that illustrate how modifications in human nutrition may become relevant to health and disease.

Resveratrol in peanuts

Peanuts are important dietary food source of resveratrol with potent antioxidant properties implicated in reducing risk of cancer, cardiovascular and Alzheimer's disease, and delaying aging. Resveratrol is a naturally occurring stilbene phytoalexin phenolic compound produced in response to a variety of biotic and abiotic stresses. This paper is a review of trans-resveratrol and related stilbenes from peanuts--their chemical structures, mechanisms for their biosynthesis, and concentrations in comparison with other major food sources. It will also discuss trans-resveratrol's absorption, bioavailability, and major health benefits; processes to enhance their biosynthesis in peanuts by biotic and abiotic stresses; process optimization for enhanced levels in peanuts and their potential food applications; and methods used for its extraction and analysis.

Molecular promiscuity of plant polyphenols in the management of age-related diseases: far beyond their antioxidant properties

The use of plant-derived polyphenols for the management of diseases has been under debate in the last decades. Most studies have focused on the specific effects of polyphenols on particular targets, while ignoring their pleiotropic character. The multitargeted character of polyphenols, a plausible consequence of their molecular promiscuity, may suppose an opportunity to fight multifactorial diseases. Therefore, a wider perspective is urgently needed to elucidate whether their rational use as bioactive food components may be valid for the management of diseases. In this chapter, we discuss the most likely targets of polyphenols that may account for their salutary effects from a global perspective. Among these targets, the modulation of signalling and energy-sensitive pathways, oxidative stress and inflammation-related processes, mitochondrial functionality, epigenetic machinery, histone acetylation and membrane-dependent processes play central roles in polyphenols' mechanisms of action.Sufficient evidence on polyphenols has accumulated for them to be considered a serious option for the management of non-communicable diseases, such as cancer and obesity, as well as infectious diseases. The remaining unresolved issues that must be seriously addressed are their bioavailability, metabolite detection, specific molecular targets, interactions and toxicity. The Xenohormesis hypothesis, which postulates that polyphenols are the product of plant evolutive adaptation to stress and conferee their resistance to mammals, offers a reasonable explanation to justify the beneficial and non-toxic effects of plant mixtures, but do not fully meet expectations. Hence, future research must be supported by the use of complex polypharmacology approaches and synergic studies focused on the understanding of the pleiotropic effects of polyphenols. Revisiting polyphenol mechanisms of action with the help of these techniques may allow for the improvement of human health and wellness by using intelligent nutritional intervention.

Effects of resveratrol on membrane biophysical properties: relevance for its pharmacological effects

The current study gathers a range of spectrophotometric and spectrofluorimetric techniques to systematically monitor the effects of resveratrol (trans-3,5,4'-trihydrostilbene) on the biophysical properties of membrane model systems consisting of unilamellar liposomes of phosphatidylcholine (DPPC) with the ultimate goal of relating these effects with some of the well documented pharmacological properties of this compound, and clarifying some controversial results reported on the literature. Physiological conditions have been pursued, such as a buffered pH control with adjusted ionic strength similar to the blood plasma conditions (pH 7.4, I=0.1M) and the study at different membrane physical states (gel phase and fluid phase) for the assessment of resveratrol-membrane: aqueous partition coefficient by derivative spectroscopy. Results obtained by fluorescence quenching and anisotropy studies indicate that resveratrol has a membrane fluidizing effect and is able to permeate the membrane even in the gel phase. These results mirror the well described antioxidant effect of resveratrol, since antioxidants have to reach peroxidised rigid membranes and increase membrane fluidity in order to interact more efficiently with lipid radicals in the disordered lipid bilayer. Location of resveratrol pointed also to a membrane distribution that is favourable for scavenging the lipid radicals and was elucidated using probes positioned at different membrane depths suggesting that this compound penetrates into the acyl membrane region but also positions its polar hydroxyl group near the headgroup region of the membrane.

Relationship between the antioxidant capacity and effect of rosemary (Rosmarinus officinalis L.) polyphenols on membrane phospholipid order

The antioxidant activity of rosemary (Rosmarinus officinalis L.) extracts is mainly due to phenolic abietane diterpenes and phenolic acids such as rosmarinic acid. In this study a comprehensive characterization of non-water-soluble and water-soluble extracts from rosemary was achieved by liquid chromatography coupled to electrospray and mass spectrometry. The antioxidant activity of these extracts and their respective major compounds (carnosic acid, carnosol, rosmadial, genkwanin, and rosmarinic acid) was analyzed and compared by using different in vitro systems. Whereas rosmarinic acid, carnosic acid, and carnosol exhibited similar antioxidant activity in a phospholipid membrane-free assay, carnosol behaved as an extremely potent antioxidant in a membrane-based assay (4-6 times stronger than the rest of the compounds). This differential antioxidant behavior suggests that factors other than the radical scavenging capability may be involved. All of the diterpenes induced severe effects on lipid order and packing of phospholipid model membranes. Rosmadial and carnosol decreased the number and/or mobility of water molecules located at the polar head group region of the membrane phospholipids as seen by Laurdan fluorescence spectroscopy. Carnosol also strongly enhanced lipid order at the hydrophobic core of the membrane. These effects throughout the bilayer correlated to the stronger antioxidant capacity of carnosol to inhibit lipid peroxidation. On the contrary, carnosic acid decreased membrane fluidity at deeper regions of the bilayer as measured by bilayer-to-micelle transition assay and self-quenching measurements by using octadecylrhodamine B. These effects may contribute to membrane stabilization and hindrance of radical propagation, which may cooperate with the electron donor ability of rosemary diterpenes in protecting the membranes against oxidative damage.

Membrane Activity-Guided Isolation of Antiproliferative and Antiplatelet Constituent from Evodiopanax Innovans

Bark of Evodiopanax innovans (Araliaceae) was subjected to membrane activity-guided extraction and chromatographic fractionation. The potency to interact with lipid membranes and change their fluidity was determined by measuring fluorescence polarization of liposomal and cell membranes. Plant preparations, including the MeOH extract and the specified fraction, reduced the fluidity of model biomembranes prepared with different phospholipids and cholesterol. Further purification led to the isolation of maltol 3- O-β-glucopyranoside, which inhibited tumor cell growth and platelet aggregation, together with rigidifying the cell membranes as well as the membrane-active antitumor compound (-)-epigallocatechin gallate and doxorubicin. The isolate at 100 μM and 1.0 mM showed growth inhibition of 13–49% against tumor cells cultured for 24 and 48 h. At 1.8–3.6 mM, it also produced 50% inhibition of platelet aggregation induced by collagen, adenosine 5′-diphosphate and thrombin. E. innovans is considered as a medicinal plant containing a potent bioactive constituent that exerts antiproliferative and antiplatelet effects through interaction with cell membranes to modify their fluidity.

Clusterin mediates TRAIL resistance in prostate tumor cells

One of the major obstacles in curing prostate cancer is the development of drug resistance to docetaxel, which is the gold standard for the treatment of this disease. It is not only imperative to discover the molecular basis of resistance but also to find therapeutic agents that can disrupt the resistant pathways. Based on initial findings that docetaxel-resistant PC3-DR and DU145-DR prostate tumor cell lines express tumor necrosis factor-related apoptosis inducing ligand (TRAIL) receptors, we examined whether TRAIL could be used as an alternative method to kill PC3-DR and DU145-DR cells. However, these tumor cells were found to be TRAIL resistant. Because PC3-DR and DU-145-DR cells were previously shown by us to be clusterin positive, we examined if clusterin could play a role in TRAIL resistance. We found that resveratrol could sensitize docetaxel-resistant tumor cells to TRAIL, and it worked by blocking clusterin expression. In particular, small interfering RNA clusterin expression in the cell lines was sufficient to produce apoptosis by TRAIL. Further analysis indicated that resveratrol functions as an effective tyrosine kinase inhibitor, similar to its analogue, piceatannol, and could inhibit Src and Jak kinases, thus resulting in loss of Stat1 activation. We have shown earlier that Stat1 is essential for gene transcription of clusterin. These results, taken together, show that resveratrol could be a useful new therapeutic agent to combat docetaxel resistance.

Melanoma vasculogenic mimicry is strongly related to reactive oxygen species level

The concept of 'vasculogenic mimicry' (VM) was introduced to describe the unique ability of highly invasive tumor cells to form capillary-like structures (CLS) and matrix-rich patterned network in three-dimensional culture that mimic embryonic vasculogenic network. Recently, we have shown that CLS formation requires apoptotic cell death through activation of caspase-3-dependent mechanism. In this study, to identify some molecular determinants driving aggressive melanoma cells to express a latent 'angiogenic program' that recapitulates the early events of CLS formation, we focused on the involvement of antioxidants (AOs) in the process of melanoma VM. We have studied the effects of resveratrol, (-)-epigallocathechin gallate, N-acetyl-cysteine (NAC) and Trolox on the ability of melanoma cells to form/destroy CLS. We observed that the formation of CLS was strongly related to reactive oxygen species level. In vivo animal experiments confirmed the involvement of reactive oxygen species level in melanoma VM. To understand the molecular mechanisms of this phenomenon, we specifically looked for induction of apoptosis and vascular endothelial growth factor (VEGF) release. Western blot analysis revealed that the level of VEGF, VEGF receptors (VEGF-Rs) and active caspase-3 dramatically decreased in cells treated with AOs. Here, we also report further experiments designed to determine whether the crosstalk between AOs and apoptosis exists in melanoma VM.

Crosstalk between apoptosis and antioxidants in melanoma vasculogenic mimicry

The concept of "vasculogenic mimicry" (VM) was introduced to describe the unique ability of highly aggressive tumor cells to form capillary-like structure (CLS) and matrix-rich patterned network in three-dimensional cultures that mimic embryonic vasculogenic network. Here, we provide the experimental evidence that CLS structure formation requires apoptotic cell death through activation of caspase-dependent mechanism. Our results indicate that the formation of CLS is also related to the reactive oxygen species (ROS) levels.

Rosemary (Rosmarinus officinalis) diterpenes affect lipid polymorphism and fluidity in phospholipid membranes

Rosemary (Rosmarinus officinalis) extracts are widely used in the food, nutraceutical and cosmetic areas. Their major bioactive components have shown antioxidant, antimicrobial, anti-inflammatory, antitumorigenic and chemopreventive activities. In this work, the bioactive compounds deriving from rosemary leaves (carnosol, CAR; carnosic acid, CA; rosmadial, RAL; genkwanin, GW; rosmarinic acid, RA) were isolated and their effects on the phase behaviour of model membranes were studied by several complementary biophysical techniques. All diterpenes studied, and specifically CAR, decreased the hydrophobic interactions between acyl chains, as well as broadened and shifted the phospholipid transition to lower temperatures into dimyristoylphosphatidylcholine (DMPC) membranes. In addition, all diterpenes and genkwanin increased the lipid order of fluid DMPC membranes, exhibiting CAR and RAL the strongest membrane-rigidifying effect. The diterpenoids, especially CA and RAL, promoted the formation of hexagonal-H(II) phases at low temperatures in dielaidoylphosphatidylethanolamine (DEPE) membranes which exhibited a smaller tube-to-tube distance compared to pure phospholipid. These diterpenes were also able of promoting isotropic structures in DEPE membranes which consisted of non-periodically ordered lipid structures as demonstrated by X-ray diffraction. In contrast, minor effects were observed by rosmarinic acid. In conclusion, diterpenes and genkwanin from rosemary show membrane-rigidifying effects which may contribute to their antioxidant capacity through hindering diffusion of free radicals.

Resveratrol induces apoptosis of human malignant B cells by activation of caspase-3 and p38 MAP kinase pathways

Red wine polyphenol, trans-resveratrol (trans-3,4',5-trihydroxy stilbene), has potent chemopreventive effects against various tumors. In this study, we found for the first time that resveratrol rapidly induces S phase cell cycle arrest of human malignant B cells including myeloma cells in dose- and time-dependent manners, followed by S phase cell cycle arrest through ATM/Chk pathway. Resveratrol-induced apoptosis occurs in association with the activation of caspase-3 and the loss of mitochondrial transmembrane potentials. In addition, resveratrol induces the phosphorylation of p38 MAP kinase, and specific inhibition of p38 MAP kinase abolishes the resveratrol-induced apoptosis, indicating that activation of the p38 MAP kinase pathway is required for inducing apoptosis in malignant B cells. These results suggest that resveratrol may have potential as a novel therapeutic agent for the patients with B cell malignancies including multiple myeloma.

Resveratrol inhibits type II phosphatidylinositol 4-kinase: A key component in pathways of phosphoinositide turn over

Resveratrol has anti-inflammatory, cardio protective and cancer chemopreventive properties. The molecular targets for resveratrol in early signaling cascades are not well understood. Resveratrol inhibits type II PtdIns 4-kinase but not PtdIns 3-kinase activity in vitro. Resveratrol directly binds to the enzyme with a Kd of 7.2 microM. Kinetic studies show that resveratrol competes with PtdIns binding. Inhibition of PtdIns 4-kinase activity by resveratrol/phenylarsine oxide reduces Jurkat cell adhesion to matrigel/fibronectin coated surfaces, suggesting a role for type II PtdIns 4-kinase in lymphocyte infiltration to the sites of inflammation.

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.

Molecular mechanisms of the chemopreventive effects of resveratrol and its analogs in carcinogenesis

Resveratrol (3,4',5-trihydroxy-trans-stilbene), a phytoalexin found in grape skins, peanuts, and red wine, has been reported to exhibit a wide range of biological and pharmacological properties. It has been speculated that dietary resveratrol could be an explanation for the so-called 'French paradox' as it may act as an antioxidant, promote nitric oxide production, inhibit platelet aggregation, and increase high-density lipoprotein cholesterol, and thereby serve as a cardioprotective agent. Recently, it has been demonstrated that resveratrol can function as a cancer chemopreventive agent, and there has been a great deal of experimental effort directed toward defining this effect. It has been shown that resveratrol and some of its analogs interfere with signal transduction pathways, modulate cell cycle-regulating proteins, and is a potent inducer of apoptosis in multiple carcinoma cell lines. This review summarizes the recent advances that have provided new insights into the molecular mechanisms underlying the promising properties of resveratrol.

Resveratrol: Preventing properties against vascular alterations and ageing

Cardiovascular diseases are the leading cause of death in developed countries where the common pathological substrate underlying this process is atherosclerosis. Several new concepts have emerged in relation to mechanisms that contribute to the regulation of the vascular diseases and associated inflammatory effects. Recently, potential antioxidants (vitamin E, polyphenols) have received much attention as potential anti-atherosclerotic agents. Among the polyphenols with health benefic properties, resveratrol, a phytoalexin of grape, seem to be a good candidate protecting the vascular walls from oxidation, inflammation, platelet aggregation, and thrombus formation. In this review, we focus on the mechanism of resveratrol cardiovascular benefic effects. We analyze, in relation with the different steps of atherosclerotic process, the resveratrol properties at multiple levels, such as cellular signaling, enzymatic pathways, apoptosis, and gene expression. We show and discuss the relationship with reactive oxygen species, regulation of pro-inflammatory genes including cycloxygenases and cytokines in molecular inflammatory and aging processes, and how the regulation of these activites by resveratrol can lead to a prevention of vascular diseases.

Blackberry extracts inhibit activating protein 1 activation and cell transformation by perturbing the mitogenic signaling pathway

Blackberries are natural rich sources of bioflavonoids and phenolic compounds that are commonly known as potential chemopreventive agents. Here, we investigated the effects of fresh blackberry extracts on proliferation of cancer cells and neoplastic transformation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), as well as the underlying mechanisms of signal transduction pathways. Using electron spin resonance, we found that blackberry extract is an effective scavenger of free radicals, including hydroxyl and superoxide radicals. Blackberry extract inhibited the proliferation of a human lung cancer cell line, A549. Pretreatment of A549 cells with blackberry extract resulted in an inhibition of 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation induced by ultraviolet B (UVB) irradiation. Blackberry extract decreased TPA-induced neoplastic transformation of JB6 P+ cells. Pretreatment of JB6 cells with blackberry extract resulted in the inhibition of both UVB- and TPA-induced AP-1 transactivation. Furthermore, blackberry extract also blocked UVB- or TPA-induced phosphorylation of ERKs and JNKs, but not p38 kinase. Overall, these results indicated that an extract from fresh blackberry may inhibit tumor promoter-induced carcinogenesis and associated cell signaling, and suggest that the chemopreventive effects of fresh blackberry may be through its antioxidant properties by blocking reactive oxygen species-mediated AP-1 and mitogen-activated protein kinase activation.

Resveratrol inhibits phenotypic and functional maturation of murine bone marrow-derived dendritic cells

This study investigated the effects of resveratrol, a natural polyphenol found in grapes and grape products such as wine and having a wide range of biological and pharmacological activities effecting on the phenotypic and functional maturation of bone marrow (BM)-derived dendritic cells (DC). Resveratrol inhibited the expression of costimulatory molecules (CD80 and CD86), and major histocompatibility complex (MHC) classes I and II significantly, and had the same effect dose-dependently on DC. Resveratrol also significantly suppressed the ability of BM-DC to produce intracellular IL-12 p40/p70 and secretory IL-12 p70 in response to lipopolysaccharides (LPS) stimulation. Resveratrol-treated DC were highly efficient in antigen capture via mannose receptor-mediated endocytosis. Also, they were poor stimulators of naïve allogeneic T-cell proliferation and induced lower levels of IL-2 in responding T cells. These results indicate the immunosuppressive properties of resveratrol, which may be therapeutically useful in controlling chronic immune and/or inflammatory diseases through the down-regulation of DC differentiation and maturation.

Targeting signal transduction pathways by chemopreventive agents

Cancer is a dynamic process that involves many complex factors, which may explain why a "magic bullet" cure for cancer has not been found. Death rates are still rising for many types of cancers, which possibly contributes to the increased interest in chemoprevention as an alternative approach to the control of cancer. This strategy for cancer control is based on the presumption that because cancer develops through a multi-step process, each step may be a prospective target for reversing or suppressing the process. Thus, the design and development of chemopreventive agents that act on specific and/or multiple molecular and cellular targets is gaining support as a rational approach to control cancer. Nutritional or dietary factors have attracted a great deal of interest because of their perceived ability to act as highly effective chemopreventive agents. They are professed as being generally safe and may have efficacy as chemopreventive agents by preventing or reversing premalignant lesions and/or reducing second primary tumor incidence. Many of these dietary compounds appear to act on multiple target signaling pathways. Some of the most interesting and well documented are resveratrol and components of tea, including EGCG, theaflavins and caffeine. This review will focus on recent work regarding three well-accepted cellular/molecular mechanisms that may at least partially explain the effectiveness of selected food factors, including those indicated above, as chemopreventive anti-promotion agents. These food compounds may act by: (1) inducing apoptosis in cancer cells; (2) inhibiting neoplastic transformation through the inhibition of AP-1 and/or NF-kappaB activation; and/or (3) suppressing COX-2 overexpression in cancer cells.

Inhibitory effect of epidermal growth factor on resveratrol-induced apoptosis in prostate cancer cells is mediated by protein kinase C-α

Resveratrol, a naturally occurring stilbene with antitumor properties, caused mitogen-activated protein kinase [MAPK, extracellular signal-regulated kinase 1/2 (ERK1/2)] activation, nuclear translocation of Ser15-phosphorylated p53, and p53-dependent apoptosis in hormone-insensitive DU145 prostate cancer cells. Exposure of these cells to epidermal growth factor (EGF) for up to 4 hours resulted in brief activation of MAPK followed by inhibition of resveratrol-induced signal transduction, p53 phosphorylation, and apoptosis. Resveratrol stimulated c-fos and c-jun expression in DU145 cells, an effect also suppressed by EGF. An inhibitor of protein kinase C (PKC)-α, -β, and -γ (CGP41251) enhanced Ser15 phosphorylation of p53 by resveratrol in the absence of EGF and blocked EGF inhibition of the resveratrol effect. EGF caused PKC-α/β phosphorylation in DU145 cells, an effect reversed by CGP41251. Activation of PKC by phorbol ester (phorbol 12-myristate 13-acetate) enhanced EGF action on ERK1/2 phosphorylation without significantly altering p53 phosphorylation by resveratrol. DU145 cells transfected with a dominant-negative PKC-α construct showed resveratrol-induced ERK1/2 phosphorylation and Ser15 phosphorylation of p53 but were unresponsive to EGF. Thus, resveratrol and EGF activate MAPK by discrete mechanisms in DU145 cells. The stilbene promoted p53-dependent apoptosis, whereas EGF opposed induction of apoptosis by resveratrol via a PKC-α-mediated mechanism. Resveratrol also induced p53 phosphorylation in LNCaP prostate cancer cells, an effect also inhibited by EGF. Inhibition of PKC activation in LNCaP cells, however, resulted in a reduction, rather than increase, in p53 activation and apoptosis, suggesting that resveratrol-induced apoptosis in these two cell lines occurs through different PKC-mediated and MAPK-dependent pathways.

Inhibition of vascular endothelial growth factor-induced angiogenesis by resveratrol through interruption of Src-dependent vascular endothelial cadherin tyrosine phosphorylation

Resveratrol, a polyphenolic compound found in grapes and other fruits, has been reported to inhibit angiogenesis with an as yet elusive mechanism. Here, we investigate the detailed mechanism by which resveratrol inhibits vascular endothelial growth factor (VEGF)-induced angiogenic effects in human umbilical endothelial cells (HUVECs). Exposure of HUVECs to 1 to 2.5 muM resveratrol significantly blocked VEGF-mediated migration and tube formation but not cell proliferation. Under the same concentrations, resveratrol failed to affect VEGF-stimulated activation of VEGF receptor, extracellular signal-regulated protein kinase 1/2, p38 mitogen-activated protein kinase, and Akt. Of interest, resveratrol, at the dose of 1 or 2.5 muM, effectively abrogated VEGF-mediated tyrosine phosphorylation of vascular endothelial (VE)-cadherin and its complex partner, beta-catenin. This inhibitory effect of resveratrol reflected on the retention of VE-cadherin at cell-cell contacts as demonstrated by immunofluorescence. Src kinase assay showed that VEGF-induced endogenous Src kinase activation was strongly inhibited by 1 and 2.5 muM resveratrol. Supportively, inhibition of Src activity by overexpression of Csk resulted in attenuation of the tyrosine phosphorylation of VE-cadherin and endothelial cell (EC) tube formation. Again, transfection with v-Src, an active form of Src, could reverse resveratrol inhibition of VE-cadherin tyrosine phosphorylation and EC tube formation. Reactive oxygen species (ROS) has been shown to be involved in VE-cadherin phosphorylation and its related functions. Flow cytometric analysis showed that VEGF stimulated an evident increase of peroxide, which was strongly attenuated by resveratrol. In addition, antioxidant N-acetyl-cysteine was demonstrated to strongly inhibit VEGF-mediated Src activation, VE-cadherin tyrosine phosphorylation, and HUVEC tube formation. Together, our data suggest that resveratrol inhibition of VEGF-induced angiogenesis was mediated by disruption of ROS-dependent Src kinase activation and the subsequent VE-cadherin tyrosine phosphorylation.

Synergistic suppression of superoxide and nitric oxide generation from inflammatory cells by combined food factors

In contrast to chemopreventive strategies using individual agents, a combination of specified compounds may be effectual to achieve desirable results with higher efficacy and lower toxicity. In the present in vitro study, we examined combinations of agents and assessed which concentrations were appropriate to yield notable synergism. L-N(G)-Monomethyl-L-arginine (L-NMMA), a synthetic inducible nitric oxide synthase (iNOS) inhibitor, and zerumbone, a natural sesquiterpene that suppresses iNOS de novo synthesis, were combined at various concentrations, with the aim to diminish combined lipopolysaccharide- and interferon-gamma-induced nitric oxide generation in a murine macrophage line, RAW264.7. Although the combinatorial effects (CEs) were antagonistic or additive at higher concentrations, significant synergism was obtained at lower concentrations where each agent alone did not cause significant inhibition. Similarly, the CEs were synergistic when (-)-epigallocatechin gallate (EGCG) and genistein were combined at lower concentrations, whereas those of two iNOS inhibitors, L-NMMA and L-N(G)-aminoethyl-L-ornithine, were either additive or antagonistic at all concentrations tested, suggesting that a combination of given agents with different action mechanisms is a prerequisite for synergistic effects. For suppression of phorbol ester-induced superoxide anion radical (O(2)*(-)) generation in differentiated HL-60 cells, the CEs of 1'-acetoxycahvicol acetate (ACA), a phenyl propanoid that suppresses O(2)*(-) generation, and O(2)*(-) dismutase were also synergistic, though only at lower concentrations. The CEs of ACA/EGCG were antagonistic or additive, even at low concentrations, suggesting that the signal transduction pathways triggered by these agents are antagonistic. The present findings suggest that individual food phytochemicals have complex interactions that can be antagonistic, additive, and/or synergistic in biological systems, depending upon certain environmental factors including concentrations. Further, these results support and emphasize the concept that combinations of different types of chemicals at low concentrations are one of the essential areas of study for chemopreventive strategies.

Inhibition of protein kinase C by resveratrol

Evidence is emerging that resveratrol (RV), a polyphenolic phytoaxelin present in dietary sources including red wine, may protect against atherosclerosis and cardiovascular disease by enhancing the integrity of the endothelium. In this study, the possibility that such beneficial effects of RV may arise from a modulation of protein kinase C (PKC)-mediated signaling was investigated by determining the effects of RV on the in vitro activities of PKC isozymes. It was found that the Ca(2+)-dependent activities of membrane-associated PKCalpha induced by either phorbol ester or diacylglycerol were potently inhibited by RV, each with an IC(50) of approximately 2 microM. The inhibitory effect of RV was also observed for conventional PKCbetaI, whereas the activities of novel PKC epsilon and atypical PKCzeta were each unaffected. The inhibition of PKCalpha activity was found to be competitive with respect to phorbol ester concentration but noncompetitive with respect to Ca(2+) and phosphatidylserine concentrations, suggesting that the RV may compete for phorbol ester-binding to the C1 domains. Supporting this, it was found that RV bound to a fusion peptide containing the C1A and C1B domains of PKCalpha. Similar to the effects of diacylglycerol and phorbol ester, the interaction of RV with the C1 domains induced the association of PKCalpha with membrane lipid vesicles, although this did not result in activation. Overall, the results suggest that the inhibitory effect of RV on PKC activity, and therefore on the associated signaling networks, may, in part, underlie the mechanism(s) by which this agent exerts its beneficial effects on endothelial and cardiovascular function. Furthermore, the effects of RV on these signaling networks are predicted to differ according to the cellular localization and the regulating PKC isozyme.

Resveratrol inhibits proliferation and induces apoptosis in human pancreatic cancer cells

INTRODUCTION

Because of lack of early diagnosis and poor therapeutic responsiveness, median survival in patients with pancreatic cancer is <6 months, and survival beyond 5 years is rare. Thus, another dimension in chemotherapeutic agents for pancreatic cancer would be beneficial to control metastatic and unresectable disease. Resveratrol, a natural product from grapes, has been shown to be chemopreventive for carcinogen-induced skin cancer and also to inhibit proliferation of oral squamous, breast, colonic, and prostate cancer cells.

AIM

To investigate the effect of resveratrol in pancreatic cancer.

METHODOLOGY

To evaluate the potential role of resveratrol on pancreatic cancer cell proliferation, two human pancreatic cancer cell lines, PANC-1 and AsPC-1, were used.

RESULTS

Resveratrol inhibited proliferation of both PANC-1 and AsPC-1 in a concentration- and time-dependent manner as measured by [ H]thymidine incorporation. Cell number of both PANC-1 and AsPC-1 was also significantly decreased following 48 and 72 hours of treatment with 100 micromol/L resveratrol. The growth inhibition induced by resveratrol was accompanied by apoptotic morphologic changes, characterized by cell rounding and cell membrane blebbing suggesting apoptosis. Propidium iodide staining of DNA, measured by flow cytometry, showed a dramatic increase in the fraction of sub-G0/G1 cells following resveratrol treatment in both PANC-1 and AsPC-1. The substantial apoptosis inducted by resveratrol on these two cell lines was confirmed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay.

CONCLUSION

These findings suggest that the natural product resveratrol may have a potent antiproliferative effect on human pancreatic cancer with induction of apoptosis. Resveratrol is likely to be valuable for the management and prevention of human pancreatic cancer.

Resveratrol induces apoptosis in LNCaP cells and requires hydroxyl groups to decrease viability in LNCaP and DU 145 cells

BACKGROUND

This study was conducted to determine the effects of resveratrol on prostate cancer cell viability through apoptosis induction and the significance of the three hydroxyl groups on resveratrol to the measured effect.

METHODS

Hormone-sensitive LNCaP cells and hormone-insensitive DU 145 cells were treated with resveratrol, tri-methoxy-resveratrol, or diethylstilbestrol (DES; the positive control for toxicity and apoptosis). Cell viability was determined by using an MTS assay. Apoptosis was determined by the appearance of apoptotic morphology, annexin V-FITC-positive intact cells, and caspase activation.

RESULTS

Resveratrol and DES decreased viability in LNCaP cells, but only resveratrol-treated cells expressed apoptotic morphology, annexin V-FITC-positive cells, and caspase activation. Tri-methoxy-resveratrol had no effect on DU 145 cell-viability and was less toxic to LNCaP cells than resveratrol.

CONCLUSION

Resveratrol was toxic to cells regardless of whether the cells were hormone-responsive or -unresponsive. This finding suggests that the cell's hormone responsive status is not an important determinant of the response to resveratrol. Furthermore, the hydroxyl-groups on resveratrol are required for cell toxicity. Finally resveratrol but not DES induced caspase-mediated apoptosis.

Cancer chemopreventive activity of resveratrol

Cancer chemopreventive agents are designed to reduce the incidence of tumorigenesis by intervening at one or more stages of carcinogenesis. Recently, resveratrol, a natural product found in the diet of humans, has been shown to function as a cancer chemopreventive agent. Resveratrol was first shown to act as an antioxidant and antimutagenic agent, thus acting as an anti-initiation agent. Further evidence indicated that resveratrol selectively suppresses the transcriptional activation of cytochrome P-450 1A1 and inhibits the formation of carcinogen-induced preneoplastic lesions in a mouse mammary organ culture model. Resveratrol also inhibits the formation of 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted mouse skin tumors in the two-stage model. The enzymatic activities of COX-1 and -2 are inhibited by resveratrol in cell-free models, and COX-2 mRNA and TPA-induced activation of protein kinase C and AP-1-mediated gene expression are suppressed by resveratrol in mammary epithelial cells. In addition, resveratrol strongly inhibits nitric oxide generation and inducible nitric oxide synthase protein expression. NF kappa B is strongly linked to inflammatory and immune responses and is associated with oncogenesis in certain models of cancer, and resveratrol suppresses the induction of this transcription factor by a number of agents. The mechanism may involve decreasing the phosphorylation and degradation of I kappa B alpha. At the cellular level, resveratrol also induces apoptosis, cell cycle delay or a block in the G(1) --> S transition phase in a number of cell lines. Thus, resveratrol holds great promise for future development as a chemopreventive agent that may be useful for several disorders. Preclinical toxicity studies are underway that should be followed by human clinical trials.

Resveratrol modulates rat macrophage functions

This study investigated the effects of trans-resveratrol (trans-3,4',5-trihydroxystilbene, RESV), a natural polyphenol from grapes with known antioxidant activity, on the respiratory-burst responses and phagocytic activity of rat macrophages. RESV at concentrations of 1-10 microM significantly and dose-dependently inhibited (a) the extracellular production of reactive oxygen intermediates (ROls) by resident peritoneal macrophages stimulated with phorbol 12-myristate 13-acetate (PMA) (a potent activator of protein kinase C, PKC) and (b) intracellular production of ROIs after opsonin-independent phagocytosis of Kluyveromyces lactis cells. Over the 10-100 microM concentration ranges, RESV likewise inhibited the production of reactive nitrogen intermediates (RNIs) by macrophages stimulated with thioglycollate. RESV concentrations above 10 microM also dose-dependently inhibited the phagocytosis of K. lactis cells. The results obtained demonstrate that RESV is a potent inhibitor of the antipathogen responses of rat macrophages and, thus, suggest that this agent may have applications in the treatment of diseases involving macrophage hyperresponsiveness.

Biological effects of resveratrol

Resveratrol (3,4',5-trihydroxy-trans-stilbene) is a common phytoalexin that is found in a few edible materials, such as grape skins, peanuts, and red wine. It has been speculated that dietary resveratrol may act as an antioxidant, promote nitric oxide production, inhibit platelet aggregation, and increase high-density lipoprotein cholesterol, and thereby serve as a cardioprotective agent. Based on epidemiological data, carcinogenesis and coronary heart disease are linked to dietary lifestyle and share a number of common pathways. Recently, it has been demonstrated that resveratrol can function as a cancer chemopreventive agent, and there has been a great deal of experimental effort directed toward defining this effect. Resveratrol has been reported to be estrogenic in transfected mammary cancer cells; however, there are conflicting results with respect to its actual estrogenic properties. In addition, resveratrol exhibits antiinflammatory, neuroprotective, and antiviral properties. In future work, some controversial in vitro biological effects need to be explored in animal models, and relevant physiological and pharmacological concentrations need to be used when assessing biological activities. This review focuses on various biological aspects of resveratrol and some issues that need to be addressed to gain a fuller appreciation of potential health benefits for human beings.

Resveratrol-induced inactivation of human gastric adenocarcinoma cells through a protein kinase C-mediated mechanism

Resveratrol, a polyphenolic phytochemical present in berries, grapes, and wine, has emerged as a promising chemopreventive candidate. Because there is scant information regarding natural agents that prevent, suppress, or reverse gastric carcinogenesis, the aim of the present study was to determine the chemopreventive potential of resveratrol against gastric cancer by investigating cellular and molecular events associated with resveratrol treatment of human gastric adenocarcinoma cells. We determined the action of resveratrol on cellular function and cellular integrity by measuring DNA synthesis, cellular proliferation, cell cycle distribution, cytolysis, apoptosis, and phosphotransferase activities of two key signaling enzymes, protein kinase C (PKC) and mitogen-activated protein kinases (ERK1/ERK2), in human gastric adenocarcinoma KATO-III and RF-1 cells. Resveratrol inhibited [3H]thymidine incorporation into cellular DNA of normally proliferating KATO-III cells and of RF-1 cells whose proliferation was stimulated with carcinogenic nitrosamines. Treatment with resveratrol arrested KATO-III cells in the G(0)/G(1) phase of the cell cycle and eventually induced apoptotic cell death, but had a minimal effect on cell lysis. Resveratrol treatment had no effect on ERK1/ERK2 activity but significantly inhibited PKC activity of KATO-III cells and of human recombinant PKCalpha. Results indicate that resveratrol has potential as a chemopreventive agent against gastric cancer because it exerts an overall deactivating effect on human gastric adenocarcinoma cells. Resveratrol-induced inhibition of PKC activity and of PKCalpha, without any change in ERK1/ERK2 activity, suggests that resveratrol utilizes a PKC-mediated mechanism to deactivate gastric adenocarcinoma cells.

Efficiency and mechanism of the antioxidant action of trans-resveratrol and its analogues in the radical liposome oxidation

trans-Resveratrol (trans-3,5,4'-trihydroxystilbene) is a nonflavonoid polyphenol reported to exert different biological activities, among them inhibition of the lipid peroxidation, scavenging of the free radicals, inhibition of the platelet aggregation, and anticancer activity as the most important. In order to enlighten the radical-scavenging mechanism of trans-resveratrol, stationary gamma-radiolytic experiments in liposomes and pulse radiolytic experiments in aqueous solutions were performed. Applying the stationary gamma-radiolysis together with the subsequent product analysis, reactions of lipid peroxyl radicals, LOO*, with trans-resveratrol and other natural antioxidants were investigated. It was found that trans-resveratrol was a better radical scavenger than vitamins E and C but similar to the flavonoids epicatechin and quercetin. The comparison of the radical-scavenging effects of trans-resveratrol and its analogues trans-4-hydroxystilbene and trans-3,5-dihydroxystilbene revealed that trans-resveratrol and trans-4-hydroxystilbene showed almost the same effect and were more efficient than trans-3,5-dihydroxystilbene. These findings indicate greater radical-scavenging activity of trans-resveratrols para-hydroxyl group than its meta-hydroxyl groups. Using the pulse radiolysis, reactions of trans-resveratrol and its analogues with trichloromethylperoxyl radicals, CCl(3)OO*, were studied. Spectral and kinetic properties of the observed transients showed great similarity between trans-resveratrol and trans-4-hydroxystilbene which seems to confirm that para-hydroxyl group of trans-resveratrol scavenges free radicals more effectively than its meta-hydroxyl groups.

Resveratrol inhibits the formation of phosphatidic acid and diglyceride in chemotactic peptide- or phorbol ester-stimulated human neutrophils

Resveratrol (trans-3,5,4'-trihydroxystilbene, Res) is a naturally occurring antioxidant found in grape berry skins and red wine. It has anti-inflammatory effects. In this study, we examined the effect of Res on the formation of phosphatidic acid (PA) and diglyceride (DG), in human neutrophils stimulated by formyl-methionyl-leucyl-phenylalanine (fMLP) or by phorbol 12-myristate 13-acetate (PMA). We measured the masses of PA and DG by using a nonradioactive method. Our results showed that Res inhibited the formation of PA in a concentration dependent manner with an IC(50) value of 42.4 and 60.9 microM in fMLP- and PMA-stimulated cells, respectively. Res also suppressed the formation of phosphatidylethanol (PEt), thereby implying inhibition of phospholipase D (PLD) activity. In addition, Res inhibited the formation of both diacylglycerol (DAG) and ether-linked acylglycerol (EAG) induced by fMLP and by PMA. Our results suggest that Res inhibition of PLD activity may contribute to its anti-inflammatory effects.

Antioxidant activity of resveratrol compared with common food additives

Resveratrol is a phenolic compound of the stilbene family present in wines and various parts of the grape, including the skin. In this study, the antioxidant and prooxidant activities of resveratrol were compared with other antioxidants (butylated hydroxytoluene [BHT], butylated hydroxyacetone [BHA], phenol, propyl gallate [PG], sodium tripolyphosphate [TPP], alpha-tocopherol, and vanillin) widely used in foods. The ability of these compounds to inhibit lipid peroxidation was as follows: BHA > resveratrol > PG > tripolyphosphate > vanillin > phenol > BHT > alpha-tocopherol, the first three inhibiting the peroxidation in a concentration-dependent manner. The order of OH* scavenger activity of the tested compounds was BHA > TPP > BHT. Resveratrol and vanillin produced between 10 to 7% and 16 to 10% inhibition of the deoxyribose attack, respectively, but they do not scavenge OH*. Neither the resveratrol analyzed nor PG or the rest of compounds reacted with H202 and must be considered inefficient in catalyzing any subsequent oxidation. The ability to scavenge HOCI was, in decreasing order, PG > resveratrol > alpha-tocopherol > phenol. The other compounds did not scavenge HOCl.

Signal transduction pathways: targets for chemoprevention of skin cancer

Chemoprevention can be defined as the use of substances to interfere with the process of cancer development. Although substantial progress has been made in elucidating the basis of carcinogenesis, further advances are needed to identify molecular and cellular targets for effective use of chemopreventive agents. Hundreds of compounds have been identified as potential chemopreventive agents. However, the safety and efficacy of each substance must be thoroughly investigated. Carcinogenesis is a multistage process in which numerous genes are affected. Many of these genes regulate important cellular functions, so they are prime targets for chemopreventive agents. A major focus of our work has been the elucidation of mechanism(s) explaining the anticancer actions attributed to several chemopreventive compounds, especially 'natural compounds' that are considered safe because they are present in commonly consumed foods and beverages. Of particular interest are selected drugs (eg aspirin) and certain dietary factors (eg green and black tea, resveratrol) and their influence on cell-signalling events coinciding with skin cancer promotion. This overview describes recent work from our laboratory and others focusing on molecular mechanisms of selected chemopreventive compounds in growth-related signal transduction pathways and skin cancer.

Neuroprotective abilities of resveratrol and other red wine constituents against nitric oxide-related toxicity in cultured hippocampal neurons

Animal and epidemiological studies suggest that polyphenol constituents of red wine possess antioxidant activities that favour protection against cardiovascular disease - the so-called. 'French paradox' - and possibly, central nervous system disorders such as Alzheimer's disease (AD) and ischaemia. In the present study, the potential of three major red wine derived-polyphenols to protect against toxicity induced by the nitric oxide free radical donors sodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1) was examined in cultured rat hippocampal cells. Both co- and post-treatments with either the stilbene resveratrol (5 - 25 microM) or the flavonoids quercetin (5 - 25 microM) and (+)-catechin (1 - 10 microM) were capable of attenuating hippocampal cell death and intracellular reactive oxygen species accumulation produced by SNP (100 microM and 1 mM, respectively). However, among the phenolic compounds tested, only the flavonoids afforded significant protection against 5 mM SIN-1-induced toxicity. The effects of phenolic constituents were shared by Trolox (100 microM), a vitamin E analogue, but not by selective inhibitors of cyclo-oxygenases (COX) and lipoxygenases (LOX). Among the phenolic compounds tested, only quercetin (10 microM) inhibited 100 microM SNP-stimulated protein kinase C (PKC) activation, whereas none of them were able to attenuate nitrite accumulation caused by SNP (100 microM). Taken together, these data suggest that the neuroprotective abilities of quercetin, resveratrol, and (+)-catechin result from their antioxidant properties rather than their purported inhibitory effects on intracellular enzymes such as COX, LOX, or nitric oxide synthase. Quercetin, however, may also act via PKC to produce its protective effects.