Sesquiterpene lactones inhibit inducible nitric oxide synthase gene expression in cultured rat aortic smooth muscle cells

Sesquiterpene Lactones: Promising Natural Compounds to Fight Inflammation

Inflammation is a crucial and complex process that reestablishes the physiological state after a noxious stimulus. In pathological conditions the inflammatory state may persist, leading to chronic inflammation and causing tissue damage. Sesquiterpene lactones (SLs) are composed of a large and diverse group of highly bioactive plant secondary metabolites, characterized by a 15-carbon backbone structure. In recent years, the interest in SLs has risen due to their vast array of biological activities beneficial for human health. The anti-inflammatory potential of these compounds results from their ability to target and inhibit various key pro-inflammatory molecules enrolled in diverse inflammatory pathways, and prevent or reduce the inflammatory damage on tissues. Research on the anti-inflammatory mechanisms of SLs has thrived over the last years, and numerous compounds from diverse plants have been studied, using in silico, in vitro, and in vivo assays. Besides their anti-inflammatory potential, their cytotoxicity, structure–activity relationships, and pharmacokinetics have been investigated. This review aims to gather the most relevant results and insights concerning the anti-inflammatory potential of SL-rich extracts and pure SLs, focusing on their effects in different inflammatory pathways and on different molecular players.

Antibacterial Photodynamic Treatment of Porphyromonas gingivalis with Toluidine Blue O and a NonLaser Red Light Source Enhanced by Dihydroartemisinin

In vitro experiments confirmed that antibacterial photodynamic treatment (aPDT) inactivates periodontal pathogens. However, more effective sterilization is needed in the complex oral environment. This study tested whether dihydroartemisinin (DHA) enhanced the photokilling effect of aPDT on Porphyromonas gingivalis (P. gingivalis) in planktonic and biofilm states. aPDT combining toluidine blue O (TBO) with 630 nm red light was performed on bacterial suspensions and biofilms in vitro with different final concentrations of DHA (10, 20 and 40 μg mL^-1 ). The sensitization mechanism was preliminarily investigated by uptake experiments. The above experiments were repeated with different incubation times (30, 60, 120 s). Porphyromonas gingivalis biofilms exhibited significantly higher resistance to aPDT than P. gingivalis in suspension under the same experimental parameters. DHA alone had no cytotoxic effect on P. gingivalis with or without light irradiation. In either bacterial suspensions or biofilms, DHA concentration-dependently enhanced the photokilling effect of aPDT and increased TBO uptake by P. gingivalis. Prolonged incubation time enhanced the photokilling efficiency of aPDT until cellular TBO uptake reached saturation. DHA can enhance aPDT activity against P. gingivalis in planktonic and biofilm states. DHA also accelerated TBO uptake, reducing incubation time.

Natural Sesquiterpene Lactones in the Prevention and Treatment of Inflammatory Disorders and cancer: A Systematic Study of this Emerging Therapeutic Approach based on Chemical and Pharmacological Aspect

Background and Introduction:

Sesquiterpene lactones are a class of secondary metabolite that contains sesquiterpenoids and lactone ring as pharmacophore moiety. A large group of bioactive secondary metabolites such as phytopharmaceuticals belong to this category. From the Asteraceae family-based medicinal plants, more than 5,000 sesquiterpene lactones have been reported so far. Sesquiterpene lactone-based pharmacophore moieties hold promise for broad-spectrum biological activities against cancer, inflammation, parasitic, bacterial, fungal, viral infection and other functional disorders. Moreover, these moiety based phytocompounds have been highlighted with a new dimension in the natural drug discovery program worldwide after the 2015 Medicine Nobel Prize achieved by the Artemisinin researchers.

Objective:

These bitter substances often contain an α, β-unsaturated-γ-lactone as a major structural backbone, which in recent studies has been explored to be associated with anti-tumor, cytotoxic, and anti-inflammatory action. Recently, the use of sesquiterpene lactones as phytomedicine has been increased. This study will review the prospect of sesquiterpene lactones against inflammation and cancer.

Methods:

Hence, we emphasized on the different features of this moiety by incorporating its structural diversity on biological activities to explore structure-activity relationships (SAR) against inflammation and cancer.

Results:

How the dual mode of action such as anti-inflammatory and anti-cancer has been exhibitedby these phytopharmaceuticals will be forecasted in this study. Furthermore, the correlation of anti-inflammatory and anti-cancer activity executed by the sesquiterpene lactones for fruitful phytotherapy will also be revealed in the present review in the milieu of pharmacophore activity relation and pharmacodynamics study as well.

Conclusion:

So, these metabolites are paramount in phytopharmacological aspects. The present discussion on the future prospect of this moiety based on the reported literature could be a guide for anti-inflammatory and anti-cancer drug discovery programs for the upcoming researchers.

Effect of artemisinin and neurectomy of pterygoid canal in ovalbumin-induced allergic rhinitis mouse model

Background

Allergic rhinitis (AR), characterized by sneezing, nasal itching and rhinorrhea, affects a large number of population. This study aimed to explore the effects of artemisinin alone or combined with neurectomy of pterygoid canal in ovalbumin-induced AR mouse model and illustrate the underlying mechanisms.

Methods

Allergic symptoms were evaluated to verify inhibitory effect of artemisinin alone or combined with neurectomy of pterygoid canal on AR. Serum levels of histamine, immunoglobulin E (IgE) and inflammatory factors TNF, INF-γ, IL-1β IL-10, IL-4 and IL-5 were measured by ELISA. The mRNA levels of TNF, INF-γ, IL-1β and IL-10 in local lymph nodes were measured by RT-qPCR. The total and phosphorylated levels of ERK and JNK were assessed by Western blot. CD4⁺CD25⁺Foxp3⁺ T (Treg) cells were analyzed by flow cytometry.

Results

Artemisinin significantly relieved the behavior symptoms of AR mice. The administration of artemisinin strikingly suppressed the expression of histamine, IgE and inflammatory factors. An increased Treg cell proportion and inhibited ERK phosphorylation were observed in artemisinin-treated groups as compared to those in the AR group. Moreover, artemisinin plus neurectomy of pterygoid almost abolished the behavioral score increase in AR mice.

Conclusions

These results indicated that artemisinin exhibited anti-allergic effect by inhibiting ERK activation and increasing Treg cell proportion, which subsequently decreased the expressions of allergic mediators. In addition, artemisinin combined with neurectomy of pterygoid showed better efficacy than artemisinin alone.

Electronic supplementary material

The online version of this article (10.1186/s13223-018-0249-6) contains supplementary material, which is available to authorized users.

Protective effect of artemisinin on chronic alcohol induced-liver damage in mice

The liver disease related to chronic alcohol consumption is one of the leading causes of death for alcoholics. The efficient drug to ameliorate the alcoholic liver injury was needed urgently. The present study was performed to investigate whether artemisinin possessed the protective effect against chronic alcohol consumption. 50 male Kunming mice were divided into 5 groups: control group (C): 10ml/kg saline+10ml/kg saline, alcohol group (A): 10ml/kg 56%(v/v) alcohol+10ml/kg saline, low dose group of artemisinin (L): 10ml/kg 56%(v/v) alcohol+30mg/kg/day artemisinin, medium dose group of artemisinin (M): 10ml/kg 56%(v/v) alcohol+60mg/kg/day artemisinin, high dose group of artemisinin (H): 10ml/kg 56%(v/v) alcohol+120mg/kg/day artemisinin. Drugs were given orally every day. The general state of mice was observed and the levels of serum activities of AST and ALT were detected after treatment with drugs for 30days. Besides, the liver weight index was calculated and histopathological analysis was performed. We successfully demonstrated that treatment with high dose of artemisinin significantly decreased the elevated levels of AST (p<0.05) and ALT (p<0.01) in plasma, as well as the liver weight index (p<0.01). The loss of body weight, tissue injury, oedema and inflammatory cell infiltration in the hepatocytes were found in the A group. These symptoms were remarkably alleviated in animals treated with artemisinin. Artemisinin can inhibit the activation of NF-кB and the expression of inflammatory cytokines inducible nitric oxide synthase. Besides, it can also enhance the stability of liver cell membrane, and reduce the damage of liver cell membrane and liver cell. Artemisinin showed a protective effect against chronic alcohol poisoning and it has a great potential for the clinical application to treat the liver injury induced by alcohol.

Emerging Anti-Mitotic Activities and Other Bioactivities of Sesquiterpene Compounds upon Human Cells

We review the bio-activities of natural product sesquiterpenes and present the first description of their effects upon mitosis. This type of biological effect upon cells is unexpected because sesquiterpenes are believed to inactivate proteins through Michael-type additions that cause non-specific cytotoxicity. Yet, certain types of sesquiterpenes can arrest cells in mitosis as measured by cell biology, biochemical and imaging techniques. We have listed the sesquiterpenes that arrest cells in mitosis and analyzed the biological data that support those observations. In view of the biochemical complexity of mitosis, we propose that a subset of sesquiterpenes have a unique chemical structure that can target a precise protein(s) required for mitosis. Since the process of mitotic arrest precedes that of cell death, it is possible that some sesquiterpenes that are currently classified as cytotoxic might also induce a mitotic arrest. Our analysis provides a new perspective of sesquiterpene chemical biology.

Protective effects of isohelenin, an inhibitor of nuclear factor κB, in endotoxic shock in rats

Recent in vitro studies have shown that isohelenin, a sesquiterpene lactone, inhibits the NF-κB pathway. This study examines the effect of isoheleninin endotoxic shock induced by administration of Escherichia coli endotoxini n male Wistar rats. A group of rats received isohelenin (2 mg/kg intraperitoneally)15 min before endotoxin. In vehicle-treated rats, administration of endotoxin caused severe hypotension, which was associated with a marked hyporeactivity to norepinephrine and acetylcholine in ex vivo aortas. Elevated levels of plasma nitrate/nitrite, metabolites of nitric oxide (NO), were also found. These inflammatory events were preceded by cytosolic degradation of inhibitor-κBα (IκBα) and activation of nuclear factor-κB (NF-κB) in the lung within 15 min of endotoxin administration. Treatment with isohelenin resulted in hemodynamicimprovement and reduced plasma levels of NO metabolites. Nuclear translocation of NF-κB was inhibited by isohelenin treatment in the lung, whereas degradation of IκBα was unchanged. In a separate set of experiments, treatment with isohelenin significantly improved survival in mice challenged with endotoxin. We conclude that isohelenin exerts beneficial therapeutic effects during endotoxic shock through inhibition of NF-κB.

Screening of saponins and sapogenins from Medicago species as potential PPARγ agonists and X-ray structure of the complex PPARγ/caulophyllogenin

A series of saponins and sapogenins from Medicago species were tested for their ability to bind and activate the nuclear receptor PPARγ by SPR experiments and transactivation assay, respectively. The SPR analysis proved to be a very powerful and fast technique for screening a large number of compounds for their affinity to PPARγ and selecting the better candidates for further studies. Based on the obtained results, the sapogenin caulophyllogenin was proved to be a partial agonist towards PPARγ and the X-ray structure of its complex with PPARγ was also solved, in order to investigate the binding mode in the ligand binding domain of the nuclear receptor. This is the first known crystal structure of a sapogenin directly interacting with PPARγ. Another compound of the series, the echinocistic acid, showed antagonist activity towards PPARγ, a property that could be useful to inhibit the adipocyte differentiation which is a typical adverse effect of PPARγ agonists. This study confirms the interest on saponins and sapogenins as a valuable natural resource exploitable in the medical and food industry for ameliorating the metabolic syndrome.

(1S,3R,8R,11S)-2,2,11-Tribromo-10-bromomethyl-3,7,7-trimethyltricyclo[6.4.0.01,3]dodec-9-ene

The title compound, C16H22Br4, was synthesized in two steps from β-himachalene, which was isolated from essential oil of the Atlas cedar (cedrus atlantica). It is built up from three fused rings, a seven-membered heptane ring, a six-membered cyclohexyl ring bearing both a bromine and a bromomethyl substituent, and a three-membered propane ring bearing two Br atoms. In the crystal, molecules are linked by C—H...Br hydrogen bonds, forming chains propagating along [001]. The absolute configuration was deduced from the chemical pathway and confirmed by resonant scattering [Flack parameter = 0.012 (10)].

HDAC and NF-κB mediated cytotoxicity induced by novel N-Chloro β-lactams and benzisoxazole derivatives

Novel N-chloro â-Lactam and benzisoxazole derivatives were successfully synthesized with excellent yields (92-96%) under simple and mild reaction conditions. The β-lactams as a class acquired importance since the discovery of penicillin which contains β-lactam unit as an essential structural feature of its molecule, this interest continued unabated because of the therapeutic importance of β-lactam antibiotics. In silico studies of the compounds with cancer drug target enzymes showed the inhibition of HDAC (Histone Deacetylase) and NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) significantly. The compounds were then investigated for the inhibitory potential against the same enzymes in vitro. NF-κB inhibition was investigated by trans activation assay using HEK293/NF-κB-luc cells. Overall, the synthesized compounds induce the cancer cell toxicity by restraining the NF-κB transcription factor mediated by HDAC inhibition and thus the compounds act as dual inhibitors.

Sesquiterpene lactone parthenolide attenuates production of inflammatory mediators by suppressing the Toll-like receptor-4-mediated activation of the Akt, mTOR, and NF-κB pathways

Microbial product lipopolysaccharide has been shown to be involved in the pathogenesis of inflammatory skin diseases. Parthenolide present in extracts of the herb feverfew has demonstrated an anti-inflammatory effect. However, the effect of parthenolide on the Akt/mTOR and NF-κB pathway activation-induced productions of inflammatory mediators in keratinocytes has not been studied. Using human keratinocytes, we investigated the effect of parthenolide on the inflammatory mediator production in relation to the Toll-like receptor-4-mediated-Akt/mTOR and NF-κB pathways, which regulate the transcription genes involved in immune and inflammatory responses. Parthenolide, Akt inhibitor, Bay 11-7085, and N-acetylcysteine each attenuated the lipopolysaccharide-induced production of IL-1β and PGE2, increase in the levels of cyclooxygenase, formation of reactive oxygen species, increase in the levels of Toll-like receptor-4, and activation of the Akt/mTOR and NF-κB in keratinocytes. The results show that parthenolide appears to attenuate the lipopolysaccharide-stimulated production of inflammatory mediators in keratinocytes by suppressing the Toll-like receptor-4-mediated activation of the Akt, mTOR, and NF-κB pathways. The activation of signaling transduction pathways appear to be regulated by reactive oxygen species. Parthenolide appears to attenuate the microbial product-mediated inflammatory skin diseases.

Anti-Inflammatory and PPAR Transactivational Effects of Oleanane-Type Triterpenoid Saponins from the Roots of Pulsatilla koreana

In this study, 23 oleanane-type triterpenoid saponins were isolated from a methanol extract of the roots of Pulsatilla koreana. The NF-κB inhibitory activity of the isolated compounds was measured in TNFα-treated HepG2 cells using a luciferase reporter system. Compounds 19–23 inhibited TNFα-stimulated NF-κB activation in a dose-dependent manner, with IC₅₀ values ranging from 0.75–8.30 μM. Compounds 19 and 20 also inhibited the TNFα-induced expression of iNOS and ICAM-1 mRNA. Moreover, effect of the isolated compounds on PPARs transcriptional activity was assessed. Compounds 7–11 and 19–23 activated PPARs the transcriptional activity significantly in a dose-dependent manner, with EC50 values ranging from 0.9–10.8 μM. These results suggest the presence of potent anti-inflammatory components in P. koreana, and will facilitate the development of novel anti-inflammatory agents.

NF-κB inhibitory activity of sucrose fatty acid esters and related constituents from Astragalus membranaceus

Twelve compounds, including six sucrose fatty acid esters (1-6), four galactosyl acylglycerols (7-10), and two sphingolipids (11 and 12), were isolated from the roots of Astragalus membranaceus . Their structures were identified on the basis of spectroscopic analysis. Among the isolated sucrose fatty acid esters, 6'-O-linoleyl sucrose (1) was identified as a new compound, and 6'-O-palmitoyl sucrose (2) and 6-O-palmitoyl sucrose (3) were isolated from nature for the first time. This is the first report on sucrose fatty acid ester components from A. membranaceus. The nuclear factor-κB (NF-κB) inhibitory activity of isolated compounds was measured in HepG2 cells stimulated with TNF-α using a luciferase reporter system. Among them, compounds 1-6 exhibited significant inhibition of NF-κB activation in a dose-dependent manner, with IC50 values ranging from 4.4 to 24.7 μM. Compounds 1-6 also exhibited inhibition of TNF-α-induced expression of iNOS and ICAM-1 mRNA and dose-dependent inhibition of iNOS promoter activity, with IC50 values ranging from 3.3 to 5.0 μM. These data demonstrate the potential of sucrose fatty acid esters from A. membranaceus to prevent and treat inflammatory diseases.

Sesquiterpenoids lactones: benefits to plants and people

Sesquiterpenoids, and specifically sesquiterpene lactones from Asteraceae, may play a highly significant role in human health, both as part of a balanced diet and as pharmaceutical agents, due to their potential for the treatment of cardiovascular disease and cancer. This review highlights the role of sesquiterpene lactones endogenously in the plants that produce them, and explores mechanisms by which they interact in animal and human consumers of these plants. Several mechanisms are proposed for the reduction of inflammation and tumorigenesis at potentially achievable levels in humans. Plants can be classified by their specific array of produced sesquiterpene lactones, showing high levels of translational control. Studies of folk medicines implicate sesquiterpene lactones as the active ingredient in many treatments for other ailments such as diarrhea, burns, influenza, and neurodegradation. In addition to the anti-inflammatory response, sesquiterpene lactones have been found to sensitize tumor cells to conventional drug treatments. This review explores the varied ecological roles of sesquiterpenes in the plant producer, depending upon the plant and the compound. These include allelopathy with other plants, insects, and microbes, thereby causing behavioural or developmental modification to these secondary organisms to the benefit of the sesquiterpenoid producer. Some sesquiterpenoid lactones are antimicrobial, disrupting the cell wall of fungi and invasive bacteria, whereas others protect the plant from environmental stresses that would otherwise cause oxidative damage. Many of the compounds are effective due to their bitter flavor, which has obvious implications for human consumers. The implications of sesquiterpenoid lactone qualities for future crop production are discussed.

The NF-κB inhibitory proteins IκBα and IκBβ mediate disparate responses to inflammation in fetal pulmonary endothelial cells

Exposure to intrauterine inflammation impairs lung growth but paradoxically protects the neonatal pulmonary vasculature from hyperoxic injury. The mechanisms mediating these contradictory effects are unknown. The objective is to identify the role of NF-κB in mediating cytoprotective and proinflammatory responses to inflammation in the fetal pulmonary endothelium. In newborn rats exposed to intra-amniotic LPS, we found increased expression of the NF-κB target gene manganese superoxide dismutase (MnSOD) in the pulmonary endothelium. Supporting these in vivo findings, LPS induced NF-κB activation and MnSOD expression in isolated fetal pulmonary arterial endothelial cells. In addition, LPS exposure caused apoptosis and suppressed cellular growth and induced P-selectin expression. LPS-induced NF-κB activation that proceeded through specific isoforms of the inhibitory protein IκB mediated these diverse responses; NF-κB signaling through IκBα degradation resulted in MnSOD upregulation and preserved cell growth, whereas NF-κB signaling through IκBβ degradation mediated apoptosis and P-selectin expression. These findings suggest that selective inhibition of NF-κB activation that results from IκBβ degradation preserves the enhanced antioxidant defense and protects the developing pulmonary vascular endothelium from ongoing inflammatory injury.

Anti-inflammatory and PPAR transactivational effects of components from the stem bark of Ginkgo biloba

Ginkgo biloba, which is considered a "living fossil", has been used for medicinal purposes for thousands of years. Currently, extracts of G. biloba are some of the most widely used herbal products and/or dietary supplements in the world. In this study, three new compounds, (2E,4E,1'R,3'S,5'R,8'S)-dihydrophaseic acid 3'-O-β-D-glucopyranoside (1), 7,8-dihydro-(R)-7-methoxyconiferyl alcohol (2), and (8S)-3-methoxy-8,4'-oxyneolignan-4,9,9'-triol 3'-O-β-D-glucopyranoside (3), and 13 known compounds (4-16) were isolated from the stem bark of G. biloba. Their structures were determined by extensive spectroscopic methods, including 1D and 2D NMR, MS, and circular dichroism spectra. Four of the compounds (1, 2, 7, and 10) inhibited TNFα-induced NF-κB transcriptional activity significantly in HepG2 cells in a dose-dependent manner, with IC₅₀ values ranging from 6.9 to 9.1 μM. Furthermore, the transcriptional inhibitory function of these compounds was confirmed based on decreases in COX-2 and iNOS gene expression in HepG2 cells. Compounds 1-5, 7, 9, 10, and 12-14 significantly activated the transcriptional activity of PPARs in a dose-dependent manner, with EC₅₀ values ranging from 0.7 to 12.8 μM. Compounds 2, 3, and 12 exhibited dose-dependent PPARα transactivational activity, with EC₅₀ values of 7.0, 3.3, and 10.1 μM, respectively. Compounds 1-3 activated PPARγ transcriptional activity, with EC₅₀ values of 11.9, 11.0, and 15.3 μM, whereas compounds 1 and 3 promoted the transactivational activity of PPARβ(δ) with EC₅₀ values of 10.7 and 11.2 μM, respectively. These results provide a scientific support for the use of G. biloba stem bark for the prevention and treatment of inflammatory and metabolic diseases. Moreover, these data provide the rationale for further studies of the potential of G. biloba stem bark in functional foods.

Anti-inflammatory triterpenoid saponins from the stem bark of Kalopanax pictus

Five new compounds, 16,23,29-trihydroxy-3-oxo-olean-12-en-28-oic acid (1), 4,23,29-trihydroxy-3,4-seco-olean-12-en-3-oate-28-oic acid (2), 3β,6β,23-trihydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranoside (3), 3-O-[2,3-di-O-acetyl-α-L-arabinopyranosyl]hederagenin 28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (4), and 3-O-[3,4-di-O-acetyl-α-L-arabinopyranosyl]hederagenin 28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (5), as well as 10 known compounds (6-15), were isolated from the stem bark of Kalopanax pictus. Compounds 1-5 and 7-14 inhibited TNFα-induced NF-κB transcriptional activity in HepG2 cells in a dose-dependent manner, with IC50 values ranging from 0.6 to 16.4 μM. Furthermore, the transcriptional inhibitory function of these compounds was confirmed on the basis of decreases in COX-2 and iNOS gene expression in HepG2 cells. The structure-activity relationship of the compounds with respect to anti-inflammatory activity is also discussed.

Cytotoxic and anti-inflammatory cembranoids from the Vietnamese soft coral Lobophytum laevigatum

Four new cembranoids, namely laevigatol A-D (1-4), and six known metabolites (5-10), were isolated from the Vietnamese soft coral Lobophytum laevigatum. The structures of these compounds were elucidated by extensive spectroscopic analyses, and the absolute stereochemistry of 1 was determined using the modified Mosher's method. Compounds 5, and 7-10 exhibited cytotoxic activity against selected human cancer cell lines. Compounds 1, 2, 8, and 9 showed dose-dependent inhibitory effects on the TNFα-induced NF-κB transcriptional activity in Hep-G2 cells. Moreover, compounds 1, 2, 8, and 9 significantly inhibited the induction of COX-2 and iNOS mRNA dose-dependently, indicating that these compounds attenuated the synthesis of these transcripts at the transcriptional level.

Parthenolide inhibits proliferation of vascular smooth muscle cells through induction of G0/G1 phase cell cycle arrest

OBJECTIVE

This study is to determine the effect of the natural product parthenolide, a sesquiterpene lactone isolated from extracts of the herb Tanacetum parthenium, on the proliferation of vascular smooth muscle cells (VSMCs).

METHODS

Rat aortic VSMCs were isolated and cultured in vitro, and treated with different concentrations of parthenolide (10, 20 and 30 mumol/L). [(3)H]thymidine incorporation was used as an index of cell proliferation. Cell cycle progression and distribution were determined by flow cytometric analysis. Furthermore, the expression of several regulatory proteins relevant to VSMC proliferation including IkappaBalpha, cyclooxygenase-2 (Cox-2), p21, and p27 was examined to investigate the potential molecular mechanism.

RESULTS

Treatment with parthenolide significantly decreased the [(3)H]thymidine incorporation into DNA by 30%~56% relative to control values in a dose-dependent manner (P<0.05). Addition of parthenolide also increased cell population at G(0)/G(1) phase by 19.2%~65.7% (P<0.05) and decreased cell population at S phase by 50.7%~84.8% (P<0.05), which is consistent with its stimulatory effects on p21 and p27. In addition, parthenolide also increased IkappaBalpha expression and reduced Cox-2 expression in a time-dependent manner.

CONCLUSION

Our results show that parthenolide significantly inhibits the VSMC proliferation by inducing G(0)/G(1) cell cycle arrest. IkappaBalpha and Cox-2 are likely involved in such inhibitory effect of parthenolide on VSMC proliferation. These findings warrant further investigation on potential therapeutic implications of parthenolide on VSMC proliferation in vivo.

THE GREEN TEA POLYPHENOL EPIGALLOCATECHIN-3-GALLATE IMPROVES SYSTEMIC HEMODYNAMICS AND SURVIVAL IN RODENT MODELS OF POLYMICROBIAL SEPSIS

Epigallocatechin-3-gallate (EGCG) is the main polyphenolic flavonoid found in green tea. Recent in vitro studies have suggested that EGCG inhibits activation of the nuclear factor-kappaB (NF-kappaB) pathway. The NF-kappaB is a transcriptional factor required for gene expression of many inflammatory mediators, including the inducible isoform of nitric oxide synthase (NOS2). Excessive NO production by NOS2 is directly linked to the vasoplegia, shock, and mortality associated with sepsis. Accordingly, we hypothesized that EGCG administration would inhibit NOS2 gene expression and thereby improve survival in a rodent model of polymicrobial sepsis. Polymicrobial sepsis was induced in male Sprague-Dawley rats (hemodynamic study) and C57BL6 mice (mortality study) via cecal ligation and double puncture (CL2P). Rodents were treated with either EGCG (10 mg/kg intraperitoneally) or vehicle at 1 and 6 h after CL2P and every 12 h thereafter. In the hemodynamic study, mean arterial blood pressure was monitored for 18 h, and rats were killed at 3, 6, and 18 h after CL2P. In the mortality study, survival was monitored for 72 h after CL2P in mice. In vehicle-treated rodents, CL2P was associated with profound hypotension and greater than 80% mortality rate. Epigallocatechin-3-gallate treatment significantly improved both the hypotension and survival. In vitro experiments further showed that EGCG inhibited activation of NF-kappaB and subsequent NOS2 gene expression in a primary culture of rat aortic smooth muscle cells. Epigallocatechin-3-gallate may therefore represent a potential nutritional supplement or pharmacologic agent in patients with sepsis.

Diarylheptanoids from Alnus hirsuta inhibit the NF-kB activation and NO and TNF-alpha production

Six diarylheptanoids (1-6) from the stem bark of Alnus hirsuta were investigated for their inhibitory activity against LPS-induced NF-kB activation and NO and TNF-alpha production. Among them, compounds 2, 3, and 6 displayed inhibitory activity against NF-kB activation and NO and TNF-alpha production with IC50 values of 9.2-9.9 microM, 18.2-19.3 microM, and 22.3-23.7 microM, respectively, in RAW264.7 cells. Three active compounds had no significant cytotoxicity in RAW264.7 cells at their effective concentrations. This is the first report of NF-kB-inhibitory activity of these compounds and supports the pharmacological use of A. hirsuta, which has been employed as a herbal medicine for the treatment of inflammatory diseases.

Parthenolide modulates the NF-kappaB-mediated inflammatory responses in experimental atherosclerosis

OBJECTIVE

Activation of transcription factor NF-kappaB is an important step in the development of vascular damage, because it controls inducible genes, including many inflammatory mediators. The pharmacological modulation of this process is the main objective in the design of new therapies for atherosclerosis. In this work we analyzed the effects of the natural compound parthenolide (PTN), an NF-kappaB inhibitor.

METHODS AND RESULTS

In vascular smooth muscle cells (VSMCs) and monocytes stimulated with lipopolysaccharide (LPS), nontoxic doses of PTN reduced IkappaBalpha degradation, NF-kappaB activation, and MCP-1 expression, without inhibiting AP-1 and MAPK. In apoE mice, treatment with low (2 mg/kg, 20 weeks), medium (4 mg/kg, 10 weeks), and high (10 mg/kg, 10 weeks) dose of PTN reduced the size of aortic lesion, decreased macrophage, and increased VSMC content in the lesions. Treated mice showed reduced serum levels of MCP-1 and attenuated NF-kappaB activity, but not AP-1, in the lesions. Moreover, PTN affects neither apoptotic cell death nor oxidative stress in cultured cells and mice.

CONCLUSIONS

NF-kappaB inhibition by PTN retards atherosclerotic lesions in apoE mice, by reducing lesion size and changing plaque composition. This natural compound could represent a novel therapeutic approach to inflammation during vascular damage.

Effect of myrrh oil on IL-1β stimulation of NF-κB activation and PGE2 production in human gingival fibroblasts and epithelial cells

Anecdotal and scientific evidence suggest that myrrh oil (MO) has anti-inflammatory properties. Subtoxic MO levels decrease interleukin (IL)-1beta-stimulated production of the inflammatory cytokine IL-6 by human gingival fibroblasts, but not epithelial cells. IL-1beta upregulates IL-6 via PGE(2), and via NF-kappaB, a transcription factor for many inflammatory mediator genes. NF-kappaB is inhibited by sesquiterpene compounds (from plants other than myrrh). This study determined MO effect on IL-1beta-stimulated PGE(2) production and NF-kappaB activation in gingival fibroblasts and epithelial cells. Cells were preincubated with MO, exposed to IL-1beta, cytoplasmic and nuclear fractions were isolated, and activated NF-kappaB was measured using an ELISA-based assay. IL-1beta increased nuclear activated NF-kappaB levels in fibroblasts and epithelial cells [10- and 2.5-fold over controls, respectively (p=0.0001)], and these increases were not significantly affected by MO. PGE(2) was measured in cell supernatants by ELISA, after preincubation with MO and exposure to IL-1beta. MO inhibited IL-1beta-stimulated PGE(2) production by fibroblasts (p=0.001), but not epithelial cells. The data suggest that gingival epithelial cells and fibroblasts may differ in the magnitude of NF-kappaB activation after IL-1beta stimulation, and that MO inhibition of IL-1beta-stimulated IL-6 production in fibroblasts is due in part to inhibition of PGE(2), but not NF-kappaB activation. (Supported by NIDCR DE-0725.).

Suppression of inducible nitric oxide synthase and cyclooxygenase-2 expression in RAW 264.7 macrophages by sesquiterpene lactones

The molecular mechanism underlying the suppression of lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma)-induced nitric oxide (NO) and prostaglandin (PG) E(2) production was investigated in RAW 264.7 macrophages treated with sesquiterpene lactones, zaluzanin-C and estafiatone, isolated from Ainsliaea. Zaluzanin-C and estafiatone decreased NO production in LPS/IFN-gamma-stimulated RAW 264.7 macrophages with an IC50 of about 6.61 microM and 3.80 microM, respectively. In addition, these compounds inhibited the synthesis of PGE(2) in LPS/IFN-gamma-treated RAW 264.7 macrophages. Furthermore, treatment with zaluzanin-C and estafiatone resulted in a decrease in inducible No Synthase (iNOS) and Cyclooxygenase-2 (COX-2) protein and mRNA expression levels. Zaluzanin-C and estafiatone inhibited nuclear factor-kappaB (NF-kappaB) activation, a transcription factor necessary for iNOS and COX-2 expression in response to LPS/IFN-gamma. This effect was accompanied by parallel reduction of phosphorylation and degradation of inhibitor of kappaB (IkB). In addition, these effects were completely blocked by treatment with cysteine, indicating that the inhibitory effect of zaluzanin-C and estafiatone might be mediated by alkylation of either NF-kappaB itself or an upstream molecule of NF-kappaB. These results demonstrate that the suppression of NF-kappaB activation by zaluzanin-C and estafiatone might be attributed to inhibition of nuclear translocation of NF-kappaB resulting from blockade of the degradation of IkappaB, leading to suppression of the expression of iNOS and COX-2, which play important roles in inflammatory signaling pathways.

Successful abrogation by thymoquinone against induction of diabetes mellitus with streptozotocin via nitric oxide inhibitory mechanism

Nitric oxide (NO) is involved in the destruction of beta-cells during the development of type I diabetes mellitus (DM). We demonstrated the possibility of rescuing beta-cells by intervention with thymoquinone (TQ) using streptozotocin (STZ) rat diabetic model. The hyperglycemic and hypoinsulinemic responses to STZ were significantly abrogated in rats cotreated with TQ, and this abrogating effect has persisted for 1 month after stopping of TQ treatment. Unlike observations recorded after diabetic chronicity of 1month, where there was a significant reduction of both serum and pancreatic nitrites, a significant increase in both nitrites was observed within the first 3 days in STZ rats, with or without lipopolysaccharide (LPS) stimulation, compared with controls and the TQ-cotreated. In vitro production of nitrite was significantly higher by 3-day-diabetic macrophages with or without stimulation compared to control or TQ-treated ones. However, 1-month-diabetic macrophages showed insignificant decrease of nitrite which turned significant upon stimulation. TQ has no effect on either IkB degradation or NF-kB activation; however, it significantly inhibited both p44/42 and p38 mitogen-activated protein kinases (MAPKs) which contribute to the transcriptional machinery of inducible nitric oxide synthase and NO production. These data emphasize the protective value of TQ against development of type I DM via NO inhibitory pathway.

Biological activity of plant extracts: novel analgesic drugs

The plant-derived secondary metabolites have, over the years, greatly contributed to our current understanding of the important mechanisms related to the process of pain transmission and treatment. Furthermore, they have permitted us to characterise receptor types and identify endogenous ligands involved in the mechanism of nociception. In this review, we discuss the recent advances that have occurred regarding plant-derived substances in the process of development of new analgesic drugs. Plants, such as Papaver somniferum, Cannabis sativa and those of the Capsicum and Salix species, have greatly accounted for the development of clinically relevant drugs which are useful for the management of pain disorders. The recent advances in our understanding of the mechanisms of action of the above plant-derived substances, together with use of molecular biology techniques, have greatly accelerated attempts to identify promising targets for the discovery of new, safe and efficient analgesic drugs. Despite the great progress which has occurred in the elucidation of pain transmission and despite decades of use, leaving aside its known undesirable sides effects, morphine continues to be one of the most used drugs in clinical practice for the treatment of pain disorders. Thus, safer and more efficacious analgesic drugs are urgently needed. A search through the literature reveals that many potentially active antinociceptive plant-derived compounds have been identified. However, studies aiming to investigate their cellular and molecular mechanisms of action and well-controlled clinical trials to prove their efficacy in humans are still lacking. Nevertheless, natural or synthetic substances that bind to vanilloid or cannabinoid receptors, or even those that are capable of modulating the endogenous ligands which bind to these receptors, are expected to soon appear to assist in the treatment of several pain disorders, including those of neuropathic or neurogenic origin.

Anti-inflammatory Activity of New Guaiane Type Sesquiterpene from Wikstroemia indica

In our investigation of in vitro anti-allergic screening of medicinal herbal extracts, the ethyl acetate extract of the root of Wikstroemia indica was observed to inhibit nitric oxide (NO) production in a lipopolysaccharide (LPS) and recombinant mouse interferon-gamma (IFN-gamma) activated murine macrophage-like cell line, RAW 264.7. Fractionation of the active extract led to the isolation of one new guaiane type sesquiterpene, indicanone (1), and two known biflavonoids, sikokianin B (2) and sikokianin C (3). 1 inhibited NO production with IC50 values at 9.3 microM and also inhibit the inducible nitric oxide synhase (iNOS) gene expression. This is the first report of NO production inhibitory activity of Wikstroemia indica and supports the pharmacological use of it, which has been employed as an herbal medicine for the treatment of inflammation.

The ambrosanolide cumanin inhibits macrophage nitric oxide synthesis: some structural considerations

Since its role in inflammatory diseases was recognized, nitric oxide (NO) has become an important mediator to evaluate anti-inflammatory agents. Sesquiterpene lactones, which occur in several medicinal plants, inhibit the NO production in macrophage-like cells. This action is probably due to a 1,4 addition reaction between its alpha,beta-unsaturated carbonyl group with sulfhydryl (SH)-containing compounds. For this reason it is believed that these compounds are cytotoxic, which restricts their therapeutic use. In this contribution, the ability of the ambrosanolide-type sesquiterpene lactone cumanin (from the Asteraceae Ambrosia psilostachya) to inhibit NO biosynthesis was evaluated in lipopolisaccharide-induced peritoneal murine macrophages and its cytotoxicity was assessed in the MTT assay. Cumanin showed a potent inhibitory effect in NO production (IC(50) = 9.38+/-0.38 microM) with low cytotoxicity. The 1,4-addition reaction of thiols was slow, which does not explain the inhibition of NO production but does explain the low cytotoxicity of cumanin with respect to other lactones.

Influence of helenanolide-type sesquiterpene lactones on gene transcription profiles in Jurkat T cells and human peripheral blood cells: anti-inflammatory and cytotoxic effects

Sesquiterpene lactones (SLs) are known to have potent anti-inflammatory and cytotoxic properties. So far, the anti-inflammatory effects have mainly been attributed to their inhibition of DNA-binding of the transcription factor NF-kappa B (p65), which is a pivotal regulator of the cellular immune response. Since NF-kappa B is involved in the transcriptional control of several pro-inflammatory and regulatory genes, we investigated the effects of one bifunctional NF-kappa B (p65) inhibiting and two monofunctional NF-kappa B (p65) inactive helenanolide-type SLs on PMA and LPS-induced mRNA expression in CD4(+) Jurkat T and human peripheral blood mononuclear cells (PBMCs) with reverse transcription real-time PCR (RT-rt-PCR). The monofunctional SLs 11 alpha,13-dihydrohelenalin acetate (DHAc) and chamissonolide significantly reduced mitogen-induced cytokine and iNOS mRNA levels in PBMCs and Jurkat T cells at low micromolar concentrations. DHAc also showed significant effects on the gene expression of the house-keeping genes GAP-DH and beta-actin, as well as on NF-ATc, p65, I-kappa B alpha, bcl-2, and cyclin D1. The bifunctional NF-kappa B inhibitor helenalin not only effectively inhibited pro-inflammatory gene expression, but also strongly down-regulated all investigated mRNA levels in a time-dependent manner. Flow cytometry and caspase-8 and -3 assays revealed that helenalin strongly and DHAc moderately induced apoptosis in Jurkat T cells, whereas chamissonolide caused cytoprotective effects. In PBMCs, DHAc and chamissonolide did not inhibit NF-kappa B (p65) DNA-binding at concentrations effective on the transcriptome. Thus, it can be concluded that the biological effects of SLs are not only due to NF-kappa B inhibition, but must be coupled to other mechanisms.

Parthenolide improves systemic hemodynamics and decreases tissue leukosequestration in rats with polymicrobial sepsis

OBJECTIVE

Nuclear factor (NF)-kappaB is a transcriptional factor required for the gene expression of many inflammatory mediators. This study was designed to investigate the biological effects of parthenolide, a specific inhibitor of NF-kappaB activation, in experimental sepsis and multiple organ failure.

DESIGN

Prospective, randomized laboratory investigation that used an established model of cecal ligation and puncture to induce polymicrobial sepsis in rats.

SETTING

University hospital laboratory.

SUBJECTS

Male Sprague Dawley rats underwent cecal ligation and puncture followed by the administration of saline solution.

INTERVENTIONS

A group of rats received parthenolide (1 mg/kg) intraperitoneally. Mean arterial blood pressure was monitored for 18 hrs, and survival rate was monitored for 4 days. In a separate experiment, rats were killed at 1, 3, 6, and 18 hrs after cecal ligation and puncture.

MEASUREMENTS AND MAIN RESULTS

In vehicle-treated animals, cecal ligation and puncture resulted in polymicrobial sepsis and was associated with 20% mortality rate, marked hypotension, and lung injury. Immunohistochemistry showed positive staining for nitrotyrosine and poly(adenosine diphosphate [ADP]-ribose) polymerase-1 (PARP-1) in thoracic aortas. There was a significant increase in plasma concentrations of tumor necrosis factor-alpha, interleukin-6, and interleukin-10. Elevated levels of myeloperoxidase activity in lung, colon, and liver were indicative of infiltration of neutrophils. These inflammatory events were associated with activation of NF-kappaB in the lung in a time-dependent fashion. In vivo treatment with parthenolide improved the hemodynamic profile and survival; reduced neutrophil infiltration in lung, colon, and liver; and reduced plasma concentrations of cytokines. Treatment with parthenolide also abolished formation of nitrotyrosine and expression of PARP-1 in thoracic aortas. These beneficial effects of parthenolide were associated with reduction of NF-kappaB activity in the lung.

CONCLUSIONS

Our data suggest that pharmacologic inhibition of NF-kappaB may represent a potential therapeutic approach in sepsis.

Artemisinin inhibits inducible nitric oxide synthase and nuclear factor NF-kB activation

Artemisinin is a natural product used as an alternative drug in the treatment of severe and multidrug-resistant malaria. In the present work we show that artemisinin shares with other sesquiterpene lactones the ability to inhibit the activation of the nuclear factor NF-kB: by this mechanism, artemisinin, as well as parthenolide, inhibits nitric oxide synthesis in cytokine-stimulated human astrocytoma T67 cells. These results suggest that artemisinin, in addition to its antiparasitic properties, could also exert a therapeutic effect on neurological complications of malaria.

Effect of sesquiterpene lactones on the expression of the activation marker CD69 and of IL-2 in T-lymphocytes in whole blood

We used flow cytometry to investigate the inhibitory effect of sesquiterpene lactones (SLs) on T-cell activation measured by the expression of its early marker CD69, and on interleukin (IL)-2, a mediator of activation, in whole blood. SLs are biologically active compounds found especially in plants from the Asteraceae family. Overnight treatment of blood with these substances led to the inhibition of CD69 and IL-2 expression. Interestingly, bifunctional SLs showed a weaker activity than monofunctional substances, which is in contradiction with the data obtained so far, using other biological test systems. Additionally, SLs did not completely inhibit CD69 or IL-2 expression. We also determined their toxicity and observed only a low effect. Up to now, studies on cytotoxicity have only been performed using cultured cell lines. From these results it may be supposed that these natural compounds preferentially show toxic effects towards transformed cell lines. Altogether, the results demonstrated that SLs effectively inhibit the activation of the T-lymphocyte response in whole blood and proved the utility of a whole blood system in studying their biological effects.

Nuclear factor-kappaB as a therapeutic target in critical care medicine

Nuclear factor-kappaB is a transcriptional factor required for the gene expression of many inflammatory mediators. Nuclear factor-kappaB activation requires removal and degradation of its inhibitor kappaB, an event that occurs after phosphorylation of inhibitor kappaB by a complex of inhibitor kappaB kinases. These events allow nuclear factor-kappaB to translocate into the nucleus, where it binds to kappaB elements and initiates transcription. Inappropriate and prolonged activation of nuclear factor-kappaB has been linked to several diseases associated with inflammatory events, including septic shock, acute respiratory distress syndrome, ischemia, and reperfusion injury. Thus, the key role of nuclear factor-kappaB in regulating inflammation makes this factor a therapeutic target for reducing tissue and organ damage. Regulation and control of nuclear factor-kappaB can be achieved by gene modification strategies or by pharmacologic inhibition of the key components of the cascade that leads to nuclear factor-kappaB activation. The purpose of our review is to describe these novel therapeutic approaches and their potential efficacy.

Inhibition of LPS-induced p42/44 MAP kinase activation and iNOS/NO synthesis by parthenolide in rat primary microglial cells

Nitric oxide (NO) has been implicated in the etiopathology of central nervous system (CNS) diseases such as multiple sclerosis (MS). Inhibition of NO synthesis has been proposed to be a possible mechanism of action of relevance in the treatment of multiple sclerosis and migraine. Here, we investigated the effect of parthenolide on inducible NO synthase (iNOS) synthesis and NO release using primary rat microglia. We found parthenolide to be an inhibitor of iNOS/NO synthesis. Investigating the molecular mechanisms by which parthenolide prevents iNOS/NO synthesis, we found that parthenolide inhibits the activation of p42/44 mitogen-activated protein kinase (MAPK), but not IkBalpha (IkappaBalpha) degradation or nuclear factor-kappaB (NF-kappaB) p65 activation. The data suggest that parthenolide might have a potential in the treatment of CNS diseases where NO is part of the pathophysiology.

Nuclear factor-kappa B inhibitors as potential novel anti-inflammatory agents for the treatment of immune glomerulonephritis

Nuclear factor (NF)-kappa B regulates several genes implicated in the inflammatory response and represents an interesting therapeutic target. We examined the effects of gliotoxin (a fungal metabolite) and parthenolide (a plant extract), which possess anti-inflammatory activities in vitro, on the progression of experimental glomerulonephritis. In the anti-Thy 1.1 rat model, gliotoxin (75 micro g/rat/day, 10 days, n = 18 rats) markedly reduced proteinuria, glomerular lesions, and monocyte infiltration. In anti-mesangial cell nephritis in mice, parthenolide (70 micro g/mouse/day, 7 days, n = 17 mice) significantly decreased proteinuria, hematuria, and glomerular proliferation. NF-kappa B activity, localized in glomerular and tubular cells, was attenuated by either gliotoxin or parthenolide, in association with diminished renal expression of monocyte chemoattractant protein-1 and inducible nitric oxide synthase. In cultured mesangial cells and monocytes, gliotoxin and parthenolide inhibited NF-kappa B activation and expression of inflammatory genes induced by lipopolysaccharide and cytokines, by blocking the phosphorylation/degradation of the I kappa B(alpha) subunit. In summary, gliotoxin and parthenolide prevent proteinuria and renal lesions by inhibiting NF-kappa B activation and expression of regulated genes. This may represent a novel approach for the treatment of immune and inflammatory renal diseases.

Parthenolide, an inhibitor of the nuclear factor-kappaB pathway, ameliorates cardiovascular derangement and outcome in endotoxic shock in rodents

Parthenolide is a sesquiterpene lactone used in folk medicine for its anti-inflammatory activity. Recent in vitro studies have shown that this compound inhibits the nuclear factor (NF)-kappaB pathway. This study examines the effect of parthenolide in endotoxic shock in rodents. Endotoxic shock was induced by administration of Escherichia coli endotoxin in rats. Three groups of rats received parthenolide (0.25, 0.5, or 1 mg/kg) 15 min before endotoxin; another group received parthenolide (1 mg/kg) 3 h after endotoxin. In vehicle-treated rats, administration of endotoxin caused severe hypotension, which was associated with a marked hyporeactivity to norepinephrine in ex vivo thoracic aortas. Immunohistochemistry showed positive staining for nitrotyrosine, poly(ADP-ribose) synthetase (PARS) and apoptosis, whereas Northern blot analysis showed increased mRNA expression of inducible nitric-oxide synthase (iNOS) in thoracic aortas. Elevated levels of plasma nitrate/nitrite were also found. Elevated lung levels of myeloperoxidase activity were indicative of infiltration of neutrophils. These inflammatory events were preceded by cytosolic degradation of inhibitor kappaBalpha (IkappaBalpha) and activation of nuclear NF-kappaB in the lung. In vivo pretreatment and post-treatment with parthenolide improved the hemodynamic profile and reduced plasma nitrate/nitrite and lung neutrophil infiltration in a dose-dependent fashion. Vascular hyporeactivity of ex vivo aortas was ameliorated. Treatment with parthenolide also abolished nitrotyrosine formation, PARS expression, and apoptosis and reduced iNOS mRNA content in thoracic aortas. DNA binding of NF-kappaB was inhibited by parthenolide in the lung, whereas degradation of IkappaBalpha was unchanged. In a separate set of experiments, pretreatment or post-treatment with parthenolide significantly improved survival in mice challenged with endotoxin. We conclude that parthenolide exerts beneficial effects during endotoxic shock through inhibition of NF-kappaB.

Sesquiterpene lactone parthenolide, an inhibitor of IkappaB kinase complex and nuclear factor-kappaB, exerts beneficial effects in myocardial reperfusion injury

Sesquiterpene lactones are extracts of common medicinal Asteracae plants used in folk medicine for their anti-inflammatory activity. Recently, in vitro studies have shown that these compounds may interfere with pro-inflammatory gene regulation. This study examines the effects of parthenolide, a sesquiterpene lactone, in experimental myocardial ischemia and reperfusion. Myocardial injury was induced in rats by 30 min occlusion and 120 min reperfusion of the left coronary artery. Parthenolide (250 or 500 microg/kg) or vehicle (0.05% Tween 80, 1 mL/kg) was administered intraperitoneally 10 min before reperfusion. In vehicle-treated rats, ischemia and reperfusion caused myocardial injury, as evaluated by infarct size, serum levels of creatine phosphokinase and by histological examination. Elevated tissue levels of myeloperoxidase activity were indicative of a significant infiltration of neutrophils. This event paralleled the occurrence of oxidative damage, as evaluated by a marked increase in tissue malondialdehyde levels. These inflammatory events were preceded by activation of the IkappaB kinase complex (IKK) and partial disappearance of inhibitor-kappaBalpha (IkappaBalpha) in the cytosol and translocation of the nuclear factor-kappaB (NF-kappaB) to the nucleus, as early as 15 min after reperfusion. Administration of parthenolide ameliorated myocardial injury, lowered serum creatine phosphokinase activity, and reduced neutrophil infiltration and the subsequent oxidative damage. These beneficial effects were associated with inhibition of IKK activity, enhanced stability of IkappaBalpha, and inhibition of nuclear translocation of NF-kappaB. The results of this study suggest that parthenolide may be beneficial for the treatment of reperfusion-induced myocardial damage by inhibition of the IKK/NF-kappaB pathway.

Cysteine 38 in p65/NF-kappaB plays a crucial role in DNA binding inhibition by sesquiterpene lactones

Sesquiterpene lactones (SLs) have potent anti-inflammatory properties. We have shown previously that they exert this effect in part by inhibiting activation of the transcription factor NF-kappaB, a central regulator of the immune response. We have proposed a molecular mechanism for this inhibition based on computer molecular modeling data. In this model, SLs directly alkylate the p65 subunit of NF-kappaB, thereby inhibiting DNA binding. Nevertheless, an experimental evidence for the proposed mechanism was lacking. Moreover, based on experiments using the SL parthenolide, an alternative mode of action has been proposed by other authors in which SLs inhibit IkappaB-alpha degradation. Here we report the construction of p65/NF-kappaB point mutants that lack the cysteine residues alkylated by SLs in our model. In contrast to wild type p65, DNA-binding of the Cys(38) --> Ser and Cys(38,120) --> Ser mutants is no longer inhibited by SLs. In addition, we provide evidence that parthenolide uses a similar mechanism to other SLs in inhibiting NF-kappaB. Contrary to previous reports, we show that parthenolide, like other SLs, inhibits NF-kappaB most probably by alkylating p65 at Cys(38). Although a slight inhibition of IkappaB degradation was detected for all SLs, the amount of remaining IkappaB was too low to explain the observed NF-kappaB inhibition.

Inhibition of inflammatory cytokine production and lymphocyte proliferation by structurally different sesquiterpene lactones correlates with their effect on activation of NF-kappaB

Many sesquiterpene lactones (Sls) are known to possess anti-inflammatory activities. To gain further insight into their structure-activity relationships and the molecular mechanism of action, four germacranolide sesquiterpene lactones which differ in the skeleton and the number of reactive centers (4beta,15-epoxy-miller-9E-enolide (1), 15-acetoxy-eremantholide B (2), a mixture of 15-(isovaleroyl)/15-(2-methyl-butyryl)-2alpha-acetoxy-miguanin (3), and 15-(2-hydroxy)-isobutyryloxy-micrantholide (4)) were investigated for their effect on production of proinflammatory cytokines (interleukin-1beta [IL-1beta], IL-6, and tumor necrosis factor-alpha [TNF-alpha]) as well as proliferation of concanavalin A (Con A) and lipopolysaccharide (LPS)-stimulated mouse lymphocytes. Compounds 1 and 3 which possess an alpha-methylene-gamma-lactone function and a conjugated carbonyl group induced a half-maximal inhibition of cytokine synthesis in adherent mouse peritoneal exudate cells at micromolar concentrations (IC(50) 0.69-1.70 microM), while compound 4 which contains only an alpha-methylene-gamma-lactone residue was less active (IC(50) > or 38 microM). Interestingly, compound 2, which carries only a conjugated keto group, displayed a potency similar to those of the bifunctional compounds 1 and 3. All four Sls suppressed proliferation of murine lymphocyte at IC(50) concentrations between 0.22 and 5.03 microM. The rank order of potency was 1 = 2 > 3 > 4. Generally, the growth of LPS-stimulated cells was more strongly influenced than those of Con A-activated lymphocytes. This effect was particularly pronounced with 4. Inhibitory concentrations correlated well with those necessary for inhibition of the transcription factor nuclear factor kappaB (NF-kappaB) observed in a previous investigation. Therefore, it can be assumed that NF-kappaB may be involved in the suppressive effect of Sls on cytokine production and lymphocyte proliferation.