Synthesis and biological evaluation of a library of resveratrol analogues as inhibitors of COX-1, COX-2 and NF-κB

Anti-inflammatory effects of Clematis chinensis Osbeck extract(AR-6) may be associated with NF-κB, TNF-α, and COX-2 in collagen-induced arthritis in rat

The root of Clematis chinensis Osbeck has been used widely in rheumatoid arthritis in Chinese traditional medicine, and AR-6 is a triterpene saponin isolated from it. In this present study, we investigated the in vivo effects of oral AR-6 in chronic rat with collagen-induced arthritis (CIA) and possible molecular mechanism. CIA was induced by immunizing 56 female Sprague-Dawley (SD) rats with chicken typeIIcollagen (CII). Following eighteen days, the immunization rats with CIA were treated with AR-6 (32, 16, 8 mg/kg), cyclophosphamide (7 mg/kg), and TGP (Total Glucosides of Paeonia) (180 mg/kg) for 7 days, and rats without CIA were given the same volume of purified water. TNF-α and IL-1β levels in peripheral blood will be measured by ELISA, and Western blot analysis will be used to detect the expression of NF-κB p65 subunits, TNF-α and COX-2, in synovial membrane. We found that therapeutic treatment with AR-6 markedly improves the paw swelling and histopathological changes. Moreover, the serum levels of pro-inflammatory cytokines TNF-α and IL-1β were markedly lowered, and the expression of NF-κB p65 subunits, TNF-α and COX-2, in the synovial membrane of CIA rats was significantly inhibited in the AR-6-treated groups. These results enable to prove that AR-6 has a potential anti-inflammatory effect in CIA rats, and its mechanism may relate to the inhibition of the expression of NF-κB p65 subunits, TNF-α and COX-2.

Resveratrol derivatives as promising chemopreventive agents with improved potency and selectivity

SCOPE

Despite scores of investigations, the actual impact of resveratrol (3,5,4'-trihydroxy-trans-stilbene) on human health, as a dietary component or supplement, remains moot. This is due to many factors, such as relatively low potency, pleiotropic mechanisms, and rapid metabolism. Nonetheless, as a promiscuous molecule that interacts with numerous targets, resveratrol can be viewed as a scaffold for designing structural relatives potentially capable of mediating more intense responses with greater mechanistic stringency.

METHODS AND RESULTS

We currently report the synthesis and biological evaluation of 92 stilbene analogs. The compounds were tested with in vitro assays for activation of quinone reductase 1, inhibition of quinone reductase 2, nitric oxide production, aromatase, NFκB, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ornithine decarboxylase, or cyclooxygenase-1 and -2, quenching of 2,2-diphenyl-1-picrylhydrazyl free radical, interaction with estrogen receptors, and as antiproliferative agents. Several compounds were found to mediate responses with much greater potency than resveratrol; some mediated pleiotropic responses, as is the case with the parent molecule, but others were highly specific or totally inactive. When administered to rats, higher serum concentrations and greater stability was demonstrated with prototype lead molecules.

CONCLUSION

Owing to structural simplicity, facile syntheses are available for large-scale production. These data support the promise of more advanced development of novel resveratrol derivatives as drug entities.

Cyclooxygenase-2 inhibitors: a literature and patent review (2009 - 2010)

INTRODUCTION

COXs catalyze the complex conversion of arachidonic acid to prostaglandins and thromboxanes, which trigger as autacoids with autocrine and paracrine biological effects many physiological and pathophysiological responses. The structural similarities of the COX-1 and -2 enzymes make the search for selective inhibitors for COX-2 versus -1 a formidable challenge.

AREAS COVERED

The present review provides a survey of the development of novel COX-2 inhibitors covering literature and patents between 2009 and 2010. The presence of a central, typically 1,2-diaryl substituted, heterocycle or carbocycle as a characteristic structural motif in many selective COX-2 inhibitors represents the basis of their classification in this review. The classification in this review includes COX-2 inhibitors based on five- and six-membered heterocycles, benzoheterocycles (e.g., benzopyrans, benzopyranones, indoles and quinolines), quinones, chalcones, natural products and miscellaneous. When available, COX-2 inhibitors are presented with their related COX-2 inhibitory potency and selectivity.

EXPERT OPINION

The availability of detailed information on the crystal structure of the COX-2 enzyme with various substrates, cofactors and inhibitors, and the recently reported increased risk of cardiovascular events associated with selective COX-2 inhibitors will further stimulate development of COX-2 inhibitors with favorable COX-2 inhibition profiles without adverse effects to the cardiovascular system.

Measurement of cyclooxygenase inhibition using liquid chromatography-tandem mass spectrometry

Because cyclooxygenases (COX) convert arachidonic acid into pro-inflammatory cyclic endoperoxides, inhibition of these enzymes and especially the inducible COX-2 form is an important therapeutic approach to manage inflammatory diseases and possibly prevent cancer. Due to side effects of existing non-selective and COX-2 selective non-steroidal anti-inflammatory agents, the discovery of new COX inhibitors continues to be an area of active investigation. Since existing assays are slow or lack specificity, a liquid chromatography-tandem mass spectrometry (LC-MS-MS) based COX inhibition assay was developed and validated for the rapid and accurate quantitative analysis of the COX product prostaglandin E(2). The assay was validated using four COX inhibitors, celecoxib, indomethacin, resveratrol, and diclofenac that exhibit different selectivities towards COX-1 and COX-2. The IC(50) values of celecoxib and resveratrol for ovine and human COX-2 were compared, and the K(m) values were determined. Since considerable inter-species variation was observed, human COX-2 should be used for the discovery of COX inhibitors intended for human use. This sensitive and accurate LC-MS-MS based assay is suitable for the rapid screening of ligands for COX-1 and COX-2 inhibition and for IC(50) determinations.

Selective synthesis and biological evaluation of sulfate-conjugated resveratrol metabolites

Five resveratrol sulfate metabolites were synthesized and assessed for activities known to be mediated by resveratrol: inhibition of tumor necrosis factor (TNF) alpha induced NFkappaB activity, cylcooxygenases (COX-1 and COX-2), aromatase, nitric oxide production in endotoxin-stimulated macrophages, proliferation of KB or MCF7 cells, induction of quinone reductase 1 (QR1), accumulation in the sub-G(1) phase of the cell cycle, and quenching of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. Two metabolites showed activity in these assays; the 3-sulfate exhibited QR1 induction, DPPH free radical scavenging, and COX-1 and COX-2 inhibitory activities and the 4'-sulfate inhibited NFkappaB induction, as well as COX-1 and COX-2 activities. Resveratrol and its 3'-sulfate and 4-sulfate inhibit NO production by NO scavenging and down-regulation of iNOS expression in RAW 264.7 cells. Resveratrol sulfates displayed low antiproliferative activity and negligible uptake in MCF7 cells.

Design, synthesis, and biological evaluation of resveratrol analogues as aromatase and quinone reductase 2 inhibitors for chemoprevention of cancer

A series of new resveratrol analogues were designed and synthesized and their inhibitory activities against aromatase were evaluated. The crystal structure of human aromatase (PDB 3eqm) was used to rationalize the mechanism of action of the aromatase inhibitor 32 (IC50 0.59 microM) through docking, molecular mechanics energy minimization, and computer graphics molecular modeling, and the information was utilized to design several very potent inhibitors, including compounds 82 (IC50 70 nM) and 84 (IC50 36 nM). The aromatase inhibitory activities of these compounds are much more potent than that for the lead compound resveratrol, which has an IC50 of 80 microM. In addition to aromatase inhibitory activity, compounds 32 and 44 also displayed potent QR2 inhibitory activity (IC50 1.7 microM and 0.27 microM, respectively) and the high-resolution X-ray structures of QR2 in complex with these two compounds provide insight into their mechanism of QR2 inhibition. The aromatase and quinone reductase inhibitors resulting from these studies have potential value in the treatment and prevention of cancer.

Resveratrol modulates RTX toxin-induced cytotoxicity through interference in adhesion and toxin production

Host-parasite contact is a prerequisite for the acute cytotoxicity of Vibrio vulnificus, which is mediated primarily by RtxA1, a repeat in toxin (RTX) toxin. We found that resveratrol (at 10 or 30 microM), a natural polyphenol, protected HeLa cells from V. vulnificus cytotoxicity. To further characterize the underlying mechanism, the effect of resveratrol was investigated at the level of the host-microbe interactions. We studied the effects of resveratrol on adhesion, motility, cytotoxicity, and RtxA1 toxin expression of V. vulnificus. In addition, the effect of resveratrol on mouse mortality caused by V. vulnificus was investigated. Resveratrol inhibited V. vulnificus motility and the microbe adhesion to host cells, critical virulence traits for many bacteria. Resveratrol also down-regulated the expression of RtxA1 toxin at the transcriptional level and thereby protected the host cells from becoming rounded and damaged. In addition, resveratrol (20mg/kg) protected CD-1 mice from V. vulnificus infection. Taken together, these results suggest that resveratrol, a modulator of host-microbe interactions, has potential for development as a new paradigm drug to treat infectious diseases.

Resveratrol and resveratrol analogues--structure-activity relationship

Resveratrol (3,4',5-trihydroxy-trans-stilbene) is a compound found in wine and is held responsible for a number of beneficial effects of red wine. Besides the prevention of heart disease and significant anti-inflammatory effects, resveratrol might inhibit tumor cell growth and even play a role in the aging process. We here describe the structure-activity relationship of resveratrol and analogues of resveratrol regarding the free radical scavenging and antitumor effects of this exciting natural compound. In addition, we have synthesized a number of analogues of resveratrol with the aim to further improve the beneficial effects of resveratrol. Our studies were based on the analysis of structural properties, which were responsible for the most important effects of this compound. Striking in vivo effects can be observed with hexahydroxystilbene (M8), the most effective synthetic analogue of resveratrol. We could show that M8 inhibits tumor as well as metastasis growth of human melanoma in two different animal models, alone and in combination with dacarbacine.

Discovery of cyclooxygenase inhibitors from medicinal plants used to treat inflammation

Eleven authenticated botanicals used in the traditional Chinese medicine Huo-Luo-Xiao-Ling Dan were screened for ligands to cyclooxygenase (COX) using pulsed ultrafiltration liquid chromatography-mass spectrometry, and a mass spectrometry-based enzyme assay was used to determine the concentration of each of 17 ligands that inhibited COX-1 or COX-2 by 50% (IC(50)). Acetyl-11-keto-beta-boswellic acid, beta-boswellic acid, acetyl-alpha-boswellic acid, acetyl-beta-boswellic acid, and betulinic acid were COX-1 selective inhibitors with IC(50) values of approximately 10 microM. Senkyunolide O and cryptotanshinone were COX-2 selective inhibitors with IC(50) values of 5 microM and 22 microM, respectively. Roburic acid and phenethyl-trans-ferulate inhibited COX-1 and COX-2 equally. COX inhibition and the IC(50) values of most of these natural product ligands have not been reported previously.

NF-kappaB inhibitory activity of cyclitols isolated from Hancornia speciosa

Hancornia speciosa Gomes (Apocynaceae) is a Brazilian plant traditionally employed to treat inflammatory conditions, among other uses. The chemopreventive effect of an ethanol extract from H. speciosa leaves (EHS) was evaluated in a battery of in vitro tests [inhibition of aromatase, NF-kappaB and ornithine decarboxylase (ODC), antioxidant response elements (ARE) induction and cell proliferation assays]. Bioassay-directed fractionation of EHS following by inhibition of 12-O-tetradecanoyl-13-acetate (TPA)-mediated NF-kB activation led to the isolation of the cyclitols quinic acid (1) (85.0+/-12.3 microM) and l-(+)-bornesitol (2) (IC(50)=27.5+/-3.8 microM), along with rutin (26.8+/-6.3 microM). Based on these lead compounds, the cyclitols per-O-acetyl-1l-(+)-bornesitol (3) (IC(50)=38.4+/-6.2 microM), myo-inositol (4) (>180.2 microM), scyllo-inositol (5) (83.0+/-13.7 microM) and beta-d-galactoside-myo-inositol (6) (52.4+/-8.4 microM) were evaluated in the assay, but found to be somewhat less active than 1 and 2. None of the compounds was active in the ARE, aromatase or ODC assays and did not inhibit proliferation of MCF-7, LNCaP, HepG2 or LU-1 cell lines at a final concentration of 20 microg/ml (equivalent to 104.07-32.76 microM).This work identifies l-(+)-bornesitol, quinic acid and rutin as NF-kappaB inhibitors of H. speciosa and suggests cyclitols, in addition to myo-inositol, are potentially useful as chemopreventive agents.

Anti-bovine viral diarrhoea virus and hepatitis C virus activity of the cyclooxygenase inhibitor SC-560

BACKGROUND

A number of compounds were examined for their inhibitory effect on bovine viral diarrhoea virus (BVDV) replication in cell cultures and found that some cyclooxygenase (COX) inhibitors had antiviral activity against the virus.

METHODS

Determination of compounds for their anti-BVDV activity was on the basis of the inhibition of virus-induced cytopathogenicity in Mardin-Darby bovine kidney (MDBK) cells. Anti-hepatitis C virus (HCV) activity was assessed by the inhibition of viral RNA synthesis in the subgenomic HCV RNA replicon cells.

RESULTS

Among the test compounds, 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (SC-560) was the most active against BVDV, and its 50% effective and cytotoxic concentrations were 10.9 +/-2.8 and 93.9 +/-24.5 microM in virus and mock-infected MDBK cells, respectively. The compound also suppressed BVDV RNA synthesis in a dose-dependent fashion. Studies on the mechanism of action revealed that SC-560 did not interfere with viral entry to the host cells. Furthermore, it was assumed that the antiviral activity of SC-560 was not associated with its inhibitory effect on COX. The combination of SC-560 and interferon-alpha was additive to synergistic in inhibiting BVDV replication. More importantly, the compound proved to be a selective inhibitor of HCV replication.

CONCLUSIONS

SC-560 and its derivative might have potential as novel antiviral agents against HCV.

Mecanismos de ação de compostos bioativos dos alimentos no contexto de processos inflamatórios relacionados à obesidade

É indiscutível o papel da dieta e dos alimentos na manutenção da saúde e na redução do risco de DCNT. Estudos epidemiológicos mostram que o aumento do consumo de alimentos de origem vegetal influencia positivamente a saúde, enquanto estudos in vitro e in vivo em modelo animal elucidam os mecanismos pelos quais compostos bioativos não nutrientes, presentes nos alimentos, atuam na manutenção da saúde e na redução do risco de doenças. A modulação da expressão de genes que codificam proteínas envolvidas em vias de sinalização celular ativadas em DCNT é um dos mecanismos de ação dos compostos bioativos, sugerindo que estes possam ser essenciais à manutenção da saúde. A biodisponibilidade dos compostos bioativos de alimentos, as suas rotas metabólicas e o modo de ação de seus metabólitos são importantes fatores no seu efeito nas DCNT. Todos esses aspectos são temas de investigações recentes, cujos resultados contribuem para a compreensão da ocorrência e desenvolvimento das DCNT e da sua relação com a dieta. Essa revisão visou discutir alguns dos mecanismos envolvidos na resposta inflamatória induzida pela obesidade, apresentar os compostos bioativos de alimentos que modulam essa resposta inflamatória e sua relação com o metabolismo desses compostos.