Novel Aza-resveratrol analogs: Synthesis,characterization and anticancer activity against breast cancer cell lines

Novel Aza-resveratrol analogs were synthesized, structurally characterized and evaluated for cytotoxic activity against MDA-MB-231 and T47D breast cancer cell lines, which exhibited superior inhibitory activity than parent resveratrol compound. The binding mechanism of these compounds with estrogen receptor-α was rationalized by molecular docking studies which indicated additional hydrogen binding interactions and tight binding in the protein cavity. Induction of Beclin-1 protein expression in breast cancer cell lines after treatment with newly synthesized resveratrol analogs indicated inhibition of growth of these cell lines through autophagy. The study highlighted the advantage of introducing the imino-linkage in resveratrol motif in enhancing the anticancer potential of resveratrol suggesting that these analogs can serve as better therapeutic agents against breast cancer and can provide starting point for building more potent analogs in future.     

4,4′-Dihydroxy-trans-stilbene,a resveratrol analogue,exhibited enhanced antioxidant activity and cytotoxicity

Resveratrol (3,5,4′-trans-trihydroxystibene) is a natural phytoalexin present in grapes and red wine, which possesses a variety of biological activities including antioxidant activity. In order to find more active antioxidant with resveratrol as the lead compound we synthesized 4,4′-dihydroxy-trans-stilbene (4,4′-DHS). The antioxidant activities of resveratrol and 4,4′-DHS were evaluated by the reaction kinetics with galvinoxyl radical or Cu(II) ions, and the inhibition effects against free-radical-induced peroxidation of human erythrocyte ghosts. It was found that 4,4′-DHS exhibits remarkably higher antioxidant activity than resveratrol. The oxidative products of resveratrol and 4,4′-DHS in the presence of Cu(II) in acetonitrile were identified as the dihydrofuran dimers by spectroscopic method, and the antioxidant mechanism for 4,4′-DHS was proposed. In addition, 4,4′-DHS exhibits remarkably higher cytotoxicity against human promyelocytic leukemia (HL-60) cells than resveratrol.     

Antiproliferative activities of resveratrol and related compounds in human hepatocyte derived HepG2 cells are associated with biochemical cell disturbance revealed by fluorescence analyses

Resveratrol is a well known polyphenol largely produced in grapevine. It is a strong antioxidant and a free radical scavenger. It exhibits several beneficial effects for health including cancer. Resveratrol antioxidant activity is essential in the prevention of chemical-induced cancer by inhibiting initiation step of carcinogenesis process but it is also considered to inhibit cancer promotion and progression steps. While the effects of resveratrol on cancer cells are widely described, the data available on the antiproliferative potential of resveratrol derivatives remain weak. Nevertheless, resveratrol analogs could exhibit stronger potentials than the parent molecule. So, we compared the cellular effects of trans-resveratrol, trans-epsilon-viniferin and their respective acetate derivatives, as well as a polyphenol mixture extracted from grapevine shoots, called vineatrol. We studied their abilities to interfere with cell proliferation, their uptake and their effects on parameters of cellular state in human hepatoma cells (HepG2). Cell growth experiments show that resveratrol triacetate presents a slightly better antiproliferative potential than resveratrol. The dimer epsilon-viniferin,as well as its pentaacetate analog, is less powerful than resveratrol, although a similar uptake kinetics in cells. Interestingly, among the tested polyphenols, vineatrol is the most potent solution, indicating a possible synergistic effect of both resveratrol and epsilon-viniferin. We took advantage of the fluorescence properties of these compounds to evidence cellular uptake by using flow cytometry. In addition, by competition assay, we demonstrate that resveratrol triacetate enters in hepatic HepG2 cells by the same way as resveratrol. By autofluorescence in situ measurement we observed that resveratrol and related compounds induce deep changes in cells activity. These changes occur mainly by increasing NADPH cell content and the number of green fluorescent cytoplasmic granular structures which may be related to an induction of detoxifying enzyme mechanisms.     

Resveratrol-salicylate derivatives as selective DNMT3 inhibitors and anticancer agents

Resveratrol is a natural polyphenol with plethora of biological activities. Resveratrol has previously shown to decrease DNA-methyltransferase (DNMT) enzymes expression and to reactivate silenced tumor suppressor genes. Currently, it seems that no resveratrol analogs have been developed as DNMT inhibitors. Recently, we reported the synthesis of resveratrol-salicylate derivatives and by examining the chemical structure of these analogs, we proposed that these compounds could exhibit DNMT inhibition especially that they resembled NSC 14778, a compound we previously identified as a DNMT inhibitor by virtual screening. Indeed, using in vitro DNMT inhibition assay, some of the resveratrol-salicylate analogs we screened in this work that showed selective inhibition against DNMT3 enzymes which were greater than resveratrol. A molecular docking study revealed key binding interactions with DNMT3A and DNMT3B enzymes. In addition, the most active analog, 10 showed considerable cytotoxicity against three human cancer cells; HT-29, HepG2 and SK-BR-3, which was greater than resveratrol. Further studies are needed to understand the anticancer mechanisms of these derivatives.     

Antimicrobial activity and effects of resveratrol on human pathogenic bacteria

Resveratrol (3,4′,5-trihydroxistilbene) is a phytoalexin commonly found in food and drinks, which is thought to possess antimicrobial activity. These effects together with its well known antioxidant properties are beneficial for the prevention of some diseases, e.g. cancer. In this study we have verified that resveratrol has antibacterial activity against all tested Gram-positive bacteria using both the disk diffusion and broth microdilution methods. Time kill assays of this compound against Gram-positive bacteria showed that its effects on the growth of bacterial cells were due to bacteriostatic action. The addition of resveratrol has allowed the identification of changes in cell morphology and DNA contents, which have been assessed through microscopic analysis and flow cytometry; this suggests that the cell cycle is affected by resveratrol. This study indicates that this compound may have potential as a natural antibacterial agent for both food preservation and medicinal use.     

Chemical modifications of resveratrol for improved protein kinase C alpha activity

Resveratrol (1) is a naturally occurring phytoalexin that affects a variety of human disease models, including cardio- and neuroprotection, immune regulation, and cancer chemoprevention. One of the possible mechanisms by which resveratrol affects these disease states is by affecting the cellular signaling network involving protein kinase C alpha (PKCα). PKCα is a member of the family of serine/threonine kinases, whose activity is inhibited by resveratrol. To study the structure-activity relationship, several monoalkoxy, dialkoxy and hydroxy analogs of resveratrol have been synthesized, tested for their cytotoxic effects on HEK293 cells, measured their effects on the membrane translocation properties of PKCα in the presence and absence of the PKC activator TPA, and studied their binding with the activator binding domain of PKCα. The analogs showed less cytotoxic effects on HEK293 cells and caused higher membrane translocation (activation) than that of resveratrol. Among all the analogs, 3, 16 and 25 showed significantly higher activation than resveratrol. Resveratrol analogs, however, inhibited phorbol ester-induced membrane translocation, and the inhibition was less than that of resveratrol. Binding studies using steady state fluorescence spectroscopy indicated that resveratrol and the analogs bind to the second cysteine-rich domain of PKCα. The molecular docking studies indicated that resveratrol and the analogs interact with the protein by forming hydrogen bonds through its hydroxyl groups. These results signify that molecules developed on a resveratrol scaffold can attenuate PKCα activity and this strategy can be used to regulate various disease states involving PKCα.     

Modulation of antioxidant enzymes,SIRT1 and NF‐κB by resveratrol and nicotinamide in alcohol‐aflatoxin B1‐induced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most commonly diagnosed cancer worldwide and is associated with poor prognosis. The current study aimed to assess the therapeutic efficacy of resveratrol when administered alone and in combination with nicotinamide against alcohol‐aflatoxin B1‐induced HCC. Results reveal that during the development and progression of cancer, there was a decline in the level of antioxidant enzymes catalase, glutathione peroxidase, glutathione reductase (GR), antioxidant glutathione, and glutathione S‐transferase, which is an enzyme of detoxification pathways. Treatment of resveratrol restored the level of catalase and glutathione peroxidase toward normal in alcohol‐aflatoxin B1‐induced HCC; however, nicotinamide worked in concert with resveratrol only in upregulating the activity of glutathione reductase, glutathione level, and glutathione S‐transferase. SIRT1 agonist resveratrol was observed to modulate the activity of antioxidant enzymes by negatively regulating the expression of nuclear factor‐κB (NF‐κB) in alcohol‐aflatoxin B1‐induced HCC, thereby suggesting a cross‐talk between antioxidant enzymes SIRT1 and NF‐κB during the development and progression of HCC and its therapeutics by resveratrol and nicotinamide.     

Resveratrol Modulates Mitochondria Dynamics in Replicative Senescent Yeast Cells

Mitochondria form a reticulum network dynamically fuse and divide in the cell. The balance between mitochondria fusion and fission is correlated to the shape, activity and integrity of these pivotal organelles. Resveratrol is a polyphenol antioxidant that can extend life span in yeast and worm. This study examined mitochondria dynamics in replicative senescent yeast cells as well as the effects of resveratrol on mitochondria fusion and fission. Collecting cells by biotin-streptavidin sorting method revealed that majority of the replicative senescent cells bear fragmented mitochondrial network, indicating mitochondria dynamics favors fission. Resveratrol treatment resulted in a reduction in the ratio of senescent yeast cells with fragmented mitochondria. The readjustment of mitochondria dynamics induced by resveratrol likely derives from altered expression profiles of fusion and fission genes. Our results demonstrate that resveratrol serves not only as an antioxidant, but also a compound that can mitigate mitochondria fragmentation in replicative senescent yeast cells.     

Protective Effects of Resveratrol on Hydrogen Peroxide Induced Toxicity in Primary Cortical Astrocyte Cultures

It is well established that the brain is particularly susceptible to oxidative damage due to its high consumption of oxygen and that astrocytes are involved in a variety of important activities for the nervous system, including a protective role against damage induced by reactive oxygen species (ROS). The use of antioxidant compounds, such as polyphenol resveratrol found in red wine, to improve endogenous antioxidant defenses has been proposed for neural protection. The aim of this study is to evaluate the putative protective effect of resveratrol against acute H₂O₂-induced oxidative stress in astrocyte cultures, evaluating ROS production, glutamate uptake activity, glutathione content and S100B secretion. Our results confirm the ability of resveratrol to counteract oxidative damage caused by H₂O₂, not only by its antioxidant properties, but also through the modulation of important glial functions, particularly improving glutamate uptake activity, increasing glutathione content and stimulating S100B secretion, which all contribute to the functional recovery after brain injury.     

Stable free radical scavenging and antiperoxidative properties of resveratrol compared in vitro with some other bioflavonoids

Stable free radical scavenging and antiperoxidative activities of resveratrol, a component of grapes and red wine, were evaluated and compared with some other known bioflavonoids (quercetin, catechin, kaempferol, myricetin, fisetin, ellagic acid and naringenin) widely present in the plant kingdom. Free radical scavenging activity was measured in an in vitro chemical system (DPPH assay), while for antiperoxidative activity, biological system comprising of hepatic and pulmonary homogenates was employed. Antiradical activity assay showed quercetin and myricetin to be stronger antiradical agents than resveratrol. Structure-activity study revealed that O-dihydroxy group on ring B of flavonoid plays a crucial role. A double bond at 2-3 position conjugated with a 4-oxo function and hydroxy groups at positions 3 and 5 also contribute towards antiradical activity of flavonoids. Resveratrol exhibited stronger antiradical activity than kaempferol and naringenin and was also more efficient than alpha-tocopherol, a known strong endogenous non-flavonoid antioxidant, used for comparison. In vitro antiperoxidative assay showed fisetin as the strongest and kaempferol as the weakest antioxidant. Resveratrol was found to be stronger antioxidant than catechin, myricetin, kaempferol and naringenin, but was weaker than quercetin, fisetin and alpha-tocopherol. Antiradical and antiperoxidative activities of resveratrol may explain its beneficial effects in disease states. Assays exhibited no direct correlation between antiradical and antiperoxidative activities of the phenolics.     

白藜芦醇的肝脏药理作用

白藜芦醇（Resveratrol,Res）是一种自然产生的含有芪类结构非黄酮类多酚化合物,主要在红葡萄酒、花生中发现。在过去几年的研究中发现白藜芦醇具有抗肿瘤、抗氧化、抗炎、降血糖、止痛、平喘等作用。有报道表明,Res对于青光眼、胰腺炎、骨关节炎等疾病具有保护作用。它可以防止和治疗心血管疾病,同时对肝脏亦有保护性作用。以下就近年来对白藜芦醇关于肝脏的药理作用的研究进展作一综述。本文主要从抗肝损伤、抗肝纤维化、抗肝癌三方面对白藜芦醇对肝脏的保护作用进行阐述。     

Anti-HIV-1 activity of resveratrol derivatives and synergistic inhibition of HIV-1 by the combination of resveratrol and decitabine

Ribonucleotide reductase inhibitors enhance the anti-HIV-1 activities of a variety of nucleoside analogs, including those that act as chain terminators and those that increase the HIV-1 mutation rate. However the use of these ribonucleotide reductase inhibitors is limited by their associated toxicities. The hydroxylated phytostilbene resveratrol has activity in a host of systems including inhibition of ribonucleotide reductase and has minimal toxicity. Here we synthesized derivatives of resveratrol and examined them for anti-HIV-1 activity and their ability to enhance the antiviral activity of decitabine, a nucleoside analog that decreases viral replication by increasing the HIV-1 mutation rate. The data demonstrates that six of the derivatives have anti-HIV-1 activity greater than resveratrol. However, only resveratrol acted in synergy with decitabine to inhibit HIV-1 infectivity. These results reveal novel resveratrol derivatives with anti-HIV-1 activity that may have mechanisms of action that differ from the drugs currently used to treat HIV-1.     

3,4,4'-Trihydroxy-trans-stilbene, an analogue of resveratrol, is a potent antioxidant and cytotoxic agent

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a naturally occurring polyphenol widely distributed in food and dietary plants. This phytochemical has been intensively studied as an efficient antioxidant and anticancer agent, and a variety of substituted stilbenes have been developed in order to improve the potency of resveratrol. In this work, we described the synthesis of 3,4,4 -trihydroxy-trans-stilbene (3,4,4'-THS), an analogue of resveratrol, and studied its antioxidant and cytotoxic activity in vitro. 3,4,4 -THS was much more efficient than resveratrol in protecting against free radical-induced lipid peroxidation, photo-sensitized DNA oxidative damage, and free radical-induced hemolysis of human red blood cells. More potent growth inhibition in cultured human leukemia cells (HL-60) was also observed for 3,4,4 -THS. The relationship between the antioxidant efficiency and cytotoxic activity was discussed, with the emphasis on inhibition of the free radical enzyme ribonucleotide reductase by antioxidants. The result that this subtle structure modification of resveratrol drastically improves its bioactivity provides important strategy to develop novel resveratrol-based molecules.     

Resveratrol with antioxidant activity inhibits matrix metalloproteinase via modulation of SIRT1 in human fibrosarcoma cells

AimsResveratrol, a silent information regulator 1 (SIRT1) activator, has been reported to act as an antioxidant contained in red wine and prevent the development of cardiovascular diseases. Histone deacetylase such as SIRT1 is involved in the regulation of lifespan extension. In this study, the effect of resveratrol on matrix metalloproteinases (MMPs) that play an important role in metastasis was examined in human fibrosarcoma cell line, HT1080.Main methodsThe effect of resveratrol on MMPs' activity was evaluated using gelatin zymography. Western blot analysis and RT-PCR assay were used to determine the effect of resveratrol on the expression level of MMP-9, MAPK and SIRT1 proteins and genes, respectively.Key findingsIt was observed that resveratrol exhibited not only antioxidant effects on lipid peroxidation and DNA oxidation but also inhibitory effects on the expression of MMP-2 and 9 in HT1080 cells stimulated with either phorbol myristate acetate or phenazine methosulfate. Furthermore, it was found that treatment with resveratrol decreased the level of MMP-9 expression via down-regulation of p-ERK, c-fos and p65. In addition, the level of SIRT1 gene expression was also enhanced by treatment of resveratrol alone but the level of MMP-9 gene expression was decreased.SignificanceThese results suggest that the activation of SIRT1 in the presence of resveratrol especially inhibits the expression of MMP-9 in HT1080 cells, providing evidence that resveratrol can be a potential candidate for chemoprevention of cancer.     

Biological activity of 3-chloro-azetidin-2-one derivatives having interesting antiproliferative activity on human breast cancer cell lines

Resveratrol (3,4′,5 tri-hydroxystilbene), a natural plant polyphenol, has gained interest as a non-toxic agent capable of inducing tumor cell death in a variety of cancer types. However, therapeutic application of these beneficial effects remains very limited due to its short biological half-life, labile properties, rapid metabolism and elimination. Different studies were undertaken to obtain synthetic analogs of resveratrol with major bioavailability and anticancer activity. We have synthesized a series 3-chloro-azetidin-2-one derivatives, in which an azetidinone nucleus connects two aromatic rings. Aim of the present study was to investigate the effects of these new 3-chloro-azetidin-2-one resveratrol derivatives on human breast cancer cell lines proliferation. Our results indicate that some azetidin-based resveratrol derivatives may become new potent alternative tools for the treatment of human breast cancer.     

Resveratrol is a selective human cytochrome P450 1A1 inhibitor.

Resveratrol (trans-3,4',5-trihydroxystilbene) is a phytoalexin compound found in juice and wine produced from dark-skinned grape cultivars and reported to have anti-inflammatory and anticarcinogenic activities. To investigate the mechanism of anticarcinogenic activities of resveratrol, the effects on cytochrome P450 (P450) were determined in human liver microsomes and Escherichia coli membranes coexpressing human P450 1A1 or P450 1A2 with human NADPH-P450 reductase (bicistronic expression system). Resveratrol slightly inhibited ethoxyresorufin O-deethylation (EROD) activity in human liver microsomes with an IC(50) of 1.1 mM. Interestingly, resveratrol exhibited potent inhibition of human P450 1A1 in a dose-dependent manner with IC(50) of 23 microM for EROD and IC(50) of 11 microM for methoxyresorufin O-demethylation (MROD). However, the inhibition of human P450 1A2 by resveratrol was not so strong (IC(50) 1.2 mM for EROD and 580 microM for MROD). Resveratrol showed over 50-fold selectivity for P450 1A1 over P450 1A2. The activities of human NADPH-P450 reductase were not significantly changed by resveratrol. In a human P450 1A1/reductase bicistronic expression system, resveratrol inhibited human P450 1A1 activity in a mixed-type inhibition (competitive-noncompetitive) with a K(i) values of 9 and 89 microM. These results suggest that resveratrol is a selective human P450 1A1 inhibitor, and may be considered for use as a strong cancer chemopreventive agent in humans.     

Resveratrol inhibits isoprostane production in young and aged rat brain

Resveratrol (3,5,4-trihydroxystilbene), a viniferin polyphenolic compound, has been shown to have neuroprotective effects and we tested its possible antioxidant activity in young and aged rat brain, evaluating, in vitro, synaptosomal 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) production as a marker of oxidative stress. We found that in young rat brain synaptosomes resveratrol perfusion had no effect on basal 8-iso-PGF2alpha production, but quenched to basal levels the increased 8-iso-PGF2alpha production induced by hydrogen peroxide. On the other hand, in aged rats, resveratrol was able to decrease 8-iso-PGF2alpha production both basally and after hydrogen peroxide-induced oxidative stimulus. In conclusion, our findings show that the antioxidant effects of resveratrol in rat brain could play a neuroprotective role in aging, when the increased burden of oxidative stress is faced by defective antioxidant mechanisms.