Panaxadiol inhibits IL-1ß secretion by suppressing zinc finger protein 91-regulated activation of non-canonical caspase-8 inflammasome and MAPKs in macrophages.

ETHNOPHARMACOLOGICAL RELEVANCE: The use of Panax ginseng C.A.Mey. in traditional Chinese medicine dates back to about 5000 years ago thanks to its several beneficial and healing properties. Panaxadiol is a triterpenoid sapogenin monomer found in the roots of Panax ginseng C.A.Mey. and has been proven to have various bio-activities such as anti-inflammatory, anti-tumour and neuroprotective effects. AIM OF THE STUDY: The present study focuses on investigating the inflammation inhibitory effect and mechanism of panaxadiol by regulating zinc finger protein 91-regulated activation of non-canonical caspase-8 inflammasome and MAPKs in macrophages. MATERIALS AND METHODS: In vitro, the underlying mechanisms by which panaxadiol inhibits ZFP91-regulated IL-1ß expression were investigated using molecular docking, western blotting, RT-PCR, ELISA, immunofluorescence, and immunoprecipitation assays. In vivo, colitis was induced by oral administration of DSS in drinking water, and peritonitis was induced by an intraperitoneal injection of alum. Recombinant adeno-associated virus (AAV serotype 9) vector was used to establish ZFP91 knockdown mouse. RESULTS: We confirmed that panaxadiol inhibited IL-1ß secretion by suppressing ZFP91 in macrophages. Further analysis revealed that panaxadiol inhibited IL-1ß secretion by suppressing ZFP91-regulated activation of non-canonical caspase-8 inflammasome. Meanwhile, panaxadiol inhibited IL-1ß secretion by suppressing ZFP91-regulated activation of MAPKs. In vivo, prominent anti-inflammatory effects of panaxadiol were demonstrated in a DSS induced acute colitis mouse model and in an alum-induced peritonitis model by suppressing ZFP91-regulated secretion of inflammatory mediators, consistent with the results of the AAV-ZFP91 knockdown in mice. CONCLUSIONS: We report for the first time that panaxadiol inhibited IL-1ß secretion by suppressing ZFP91-regulated activation of non-canonical caspase-8 inflammasome and MAPKs, providing evidence for anti-inflammation mechanism of panaxadiol treatment for inflammatory diseases.

Baicalein inhibits TNF-α-induced NF-κB activation and expression of NF-κB-regulated target gene products.

The nuclear factor-κB (NF-κB) transcription factors control many physiological processes including inflammation, immunity, apoptosis and angiogenesis. In our search for NF-κB inhibitors from natural resources, we identified baicalein from Scutellaria baicalensis as an inhibitor of NF-κB activation. As examined by the NF-κB luciferase reporter assay, we found that baicalein suppressed TNF-α-induced NF-κB activation in a dose-dependent manner. It also inhibited TNF-α-induced nuclear translocation of p65 through inhibition of phosphorylation and degradation of IκBα. Furthermore, baicalein blocked the TNF-α-induced expression of NF-κB target genes involved in anti-apoptosis (cIAP-1, cIAP-2, FLIP and BCL-2), proliferation (COX-2, cyclin D1 and c-Myc), invasion (MMP­9), angiogenesis (VEGF) and major inflammatory cytokines (IL-8 and MCP1). The flow cytometric analysis indicated that baicalein potentiated TNF-α-induced apoptosis and induced G1 phase arrest in HeLa cells. Moreover, baicalein significantly blocked activation of p38, extracellular signal-regulated kinase 1/2 (ERK1/2). Our results imply that baicalein could be a lead compound for the modulation of inflammatory diseases as well as certain cancers in which inhibition of NF-κB activity may be desirable.

A new kaurane diterpenoid from Isodon inflexus.

A new 7,20-epoxy kaurane diterpenoid, 15-acetyldemethylkamebacetal A (1) and six known kaurane diterpenoids (2-7) were isolated from the aerial parts of Isodon inflexus in nuclear transcription factor-κB (NF-κB)-dependent reporter gene assay-guided fractionation. Their chemical structures were determined on the basis of extensive spectroscopic analysis (UV, IR, MS, 1D- and 2D-NMR) and comparison with literature data. The isolated compounds were evaluated for their inhibitory effects on TNF-α-induced NF-κB activation, and all compounds exhibited NF-κB inhibitory activities with IC50 values ranging from 1.91 to 20.15 µM.

4',6-Dihydroxy-4-methoxyisoaurone inhibits TNF-α-induced NF-κB activation and expressions of NF-κB-regulated target gene products.

The nuclear factor-κB (NF-κB) transcription factors control many physiological processes including inflammation, apoptosis, and angiogenesis. In our search for NF-κB inhibitors from natural resources, we identified 4',6-dihydroxy-4-methoxyisoaurone (ISOA) as an inhibitor of NF-κB activation from the seeds of Trichosanthes kirilowii. However, the mechanism by which ISOA inhibits NF-κB activation is not fully understood. In the present study, we demonstrated the effect of ISOA on NF-κB activation in TNF-α-stimulated HeLa cells. This compound suppressed NF-κB activation through the inhibition of IκB kinase (IKK) activation. ISOA also has an influence on upstream signaling of IKK through the inhibition of expression of adaptor proteins, TNF receptor-associated factor 2 (TRAF2) and receptor interacting protein 1 (RIP1). Consequently, ISOA blocked the phosphorylation and degradation of the inhibitor of NF-κB alpha (IκBα), and subsequent phosphorylation and nuclear translocation of p65. The suppression of NF-κB activation by ISOA led to the down-regulation of target genes involved in inflammation, proliferation, as well as potentiation of TNF-α-induced apoptosis. Taken together, this study extends our understanding on the mechanisms underlying the anti-inflammatory and anti-cancer activities of ISOA. Our findings provide new insight into the molecular mechanisms and a potential application of ISOA for inflammatory diseases as well as certain cancers.

Blockade of TNF-α-induced NF-κB signaling pathway and anti-cancer therapeutic response of dihydrotanshinone I.

The nuclear factor-κB (NF-κB) transcription factors control many physiological processes including inflammation, immunity, apoptosis, and angiogenesis. We identified dihydrotanshinone I as an inhibitor of NF-κB activation through our research on Salvia miltiorrhiza Bunge. In this study, we found that dihydrotanshinone I significantly inhibited the expression of NF-κB reporter gene induced by TNF-α in a dose-dependent manner. And dihydrotanshinone I also inhibited TNF-α induced phosphorylation and degradation of IκBα, phosphorylation and nuclear translocation of p65. Furthermore, pretreatment of cells with this compound prevented the TNF-α-induced expression of NF-κB target genes, such as anti-apoptosis (cIAP-1 and FLIP), proliferation (COX-2), invasion (MMP-9), angiogenesis (VEGF), and major inflammatory cytokines (TNF-α, IL-6, and MCP1). We also demonstrated that dihydrotanshinone I potentiated TNF-α-induced apoptosis. Moreover, dihydrotanshinone I significantly impaired activation of extracellular signal-regulated kinase 1/2 (ERK1/2), p38 and stress-activated protein kinase/c-Jun NH2-terminal kinase (JNK/SAPK). In vivo studies demonstrated that dihydrotanshinone I suppressed the growth of HeLa cells in a xenograft tumor model, which could be correlated with its modulation of TNF-α production. Taken together, dihydrotanshinone I could be a valuable candidate for the intervention of NF-κB-dependent pathological conditions such as inflammation and cancer.

Celastrol induces the apoptosis of breast cancer cells and inhibits their invasion via downregulation of MMP-9.

Celastrol is a quinone methide triterpene derived from Tripterygium wilfordii Hook F., a plant used in traditional medicine. In the present study, we reported that celastrol potentiated tumor necrosis factor-α (TNF-α)-induced apoptosis, affected activation of caspase-8, caspase-3 and PARP cleavage, and inhibited the expression of anti-apoptotic proteins such as cellular inhibitor of apoptosis protein 1 and 2 (cIAP1 and cIAP2), cellular FLICE-inhibitory protein (FLIP), and B-cell lymphoma 2 (Bcl-2). In addition, celastrol significantly reduced the invasion of MDA-MB-231 human breast cancer cells after TNF-α stimulation. As matrix metalloproteinase-9 (MMP-9) plays a critical role in tumor metastasis, we analyzed its expression with celastrol treatment. Western blot analysis and real-time PCR showed that celastrol dose-dependently suppressed TNF-α-induced MMP-9 gene expression at both the mRNA and protein levels in MDA-MB-231 cells. Taken together, our findings indicate that celastrol may be a potential candidate for breast cancer chemotherapy.

A new phenyl glycoside from the aerial parts of Equisetum hyemale.

A new phenyl glycoside, 2-(sophorosyl)-1-(4-hydroxyphenyl)ethanone (9), was isolated from the ethanolic extract of the aerial parts of Equisetum hyemale L., together with eight known compounds (1-8). The structures of these compounds were elucidated using a combination of spectroscopic analyses and chemical method. Of these nine compounds, 4 and 7 showed hepatoprotective effects towards tacrine-induced cytotoxicity in Hep 3B cells with EC50 values of 42.7 ± 1.5 and 132.6 ± 2.8 µM, respectively.

Hepatoprotective effects of Sedum sarmentosum on D-galactosamine/lipopolysaccharide-induced murine fulminant hepatic failure.

The hepatoprotective effects of sarmentosin-containing extracts of Sedum sarmentosum (SS) in D-galactosamine (D-GalN) / lipopolysaccharide (LPS)-induced fulminant hepatic failure mouse model. Pretreatment with SS markedly protected mice from lethal liver injury, which has known to be associated with an abrupt elevation of serum tumor necrosis factor (TNF)-α level. Indeed, SS significantly blocked the elevation of TNF-α and alanine aminotransferase and aspartate aminotransferase as well. SS also remarkably reduced number of apoptotic hepatocytes and DNA fragmentation in the liver, which correlated with blockade of caspase-3 activation. In addition, SS suppressed the increased expression of toll-like receptor 4 (TLR4). The activation of c-Jun NH(2)-terminal kinase, extracellular signal-regulated kinase, and p38 induced by D-GalN/LPS was also significantly suppressed by SS treatment. Furthermore, SS significantly inhibited the activation of nuclear factor-κB. In RAW 264.7 cells stimulated with LPS, TNF-α release and TLR4 expression was suppressed by SS pretreatment, which was in line with in vivo results. These findings suggested that SS prevents D-GalN/LPS-induced fulminant hepatic failure, and this protection is likely associated with its anti-apoptotic activity and the down-regulation of mitogen activated protein kinase activity associated at least in part with suppressing the transcription of LPS receptors.

Cytotoxic prenylated flavonoids from Morus alba.

A phytochemical fractionation of the methanol extract of the Morus alba leaves led to the isolation of eleven flavonoids (1-11). The structure of the new 3'-geranyl-3-prenyl-2',4',5,7-tetrahydroxyflavone (1) was elucidated by means of spectroscopic methods. The cytotoxicity of the isolated compounds against human cervical carcinoma HeLa, human breast carcinoma MCF-7, and human hepatocarcinoma Hep3B cells was evaluated. Of note, morusin (9) was the most potent with an IC(50) value of 0.64 µM against HeLa cells.

An isoaurone and other constituents from Trichosanthes kirilowii seeds inhibit hypoxia-inducible factor-1 and nuclear factor-kappaB.

Hypoxia-inducible factor-1 and nuclear factor-kappaB have become important targets in cancer treatment due to their critical role in the regulation of genes involved in tumorigenesis. Bioassay-guided fractionation of the methanol extract of Trichosanthes kirilowii seeds led to the isolation of a naturally rare isoaurone, 4',6-dihydroxy-4-methoxyisoaurone (1), together with three known compounds, cucurbitacin B (2), 6-(3-hydroxy-4-methoxystyryl)-4-methoxy-2H-pyran-2-one (3), and blumenol A (4). All compounds inhibited HIF-1 and NF-kappaB activities in reporter assays. Compounds 1-3 potently inhibited HIF-1alpha accumulation and VEGF secretion under hypoxic condition. These results suggest that the tumor cell growth inhibitory activity of T. kirilowii is likely associated with the inhibition of HIF-1 and NF-kappaB activities.

Eupatolide inhibits lipopolysaccharide-induced COX-2 and iNOS expression in RAW264.7 cells by inducing proteasomal degradation of TRAF6.

Inula britannica is a traditional medicinal plant used to treat bronchitis, digestive disorders, and inflammation in Eastern Asia. Here, we identified eupatolide, a sesquiterpene lactone from I. britannica, as an inhibitor of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression. Eupatolide inhibited the production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) as well as iNOS and COX-2 protein expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Eupatolide dose-dependently decreased the mRNA levels and the promoter activities of COX-2 and iNOS in LPS-stimulated RAW264.7 cells. Moreover, eupatolide significantly suppressed the LPS-induced expression of nuclear factor-kappa B (NF-kappaB) and activator protein-1 (AP-1) reporter genes. Pretreatment of eupatolide inhibited LPS-induced phosphorylation and degradation of I kappaB alpha, and phosphorylation of RelA/p65 on Ser-536 as well as the activation of mitogen-activated protein kinases (MAPKs) and Akt in LPS-stimulated RAW264.7 cells. Eupatolide induced proteasomal degradation of tumor necrosis factor receptor-associated factor-6 (TRAF6), and subsequently inhibited LPS-induced TRAF6 polyubiquitination. These results suggest that eupatolide blocks LPS-induced COX-2 and iNOS expression at the transcriptional level through inhibiting the signaling pathways such as NF-kappaB and MAPKs via proteasomal degradation of TRAF6. Taken together, eupatolide may be a novel anti-inflammatory agent that induces proteasomal degradation of TRAF6, and a valuable compound for modulating inflammatory conditions.

The sesquiterpene lactone eupatolide sensitizes breast cancer cells to TRAIL through down-regulation of c-FLIP expression.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising candidate for cancer therapeutics due to its ability to induce apoptosis selectively in cancer cells. However, sensitivity of cancer cells for induction of apoptosis by TRAIL varies considerably. Therefore, it is important to develop agents that overcome this resistance. We show, for the first time, that eupatolide, the sesquiterpene lactone isolated from the medicinal plant Inula britannica, sensitizes human breast cancer cells to TRAIL-induced apoptosis. Treatment with TRAIL in combination with subtoxic concentrations of eupatolide enhanced the TRAIL-induced cytotoxicity in MCF-7, MDA-MB-231 and MDA-MB-453 breast cancer cells, whereas each reagent alone slightly induced cell death. The combination induced sub-G1 phase DNA content and annexin V-staining in MCF-7 cells, which are major features of apoptosis. Apoptotic characteristics induced by the combined treatment were significantly inhibited by a pan-caspase inhibitor. The sensitization to TRAIL-induced apoptosis was accompanied by the activation of caspase-8 and was concomitant with Bid and poly(ADP-ribose) polymerase (PARP) cleavage. Treatment of eupatolide alone significantly down-regulated the expression of cellular FLICE inhibitory protein (c-FLIP) in MCF-7 cells. Furthermore, enforced expression of c-FLIP significantly attenuated the apoptosis induced by this combination in MCF-7 cells, suggesting a key role for c-FLIP down-regulation in these events. We also observed that euaptolide inhibited AKT phosphorylation in a dose- and time-dependent manner. Moreover, inhibition of Akt by LY294002, a specific PI3K inhibitor, down-regulated c-FLIP expression in MCF-7 cells. Taken together, these results indicate that eupatolide could augment TRAIL-induced apoptosis in human breast cancer cells by down-regulating c-FLIP expression through the inhibition of AKT phosphorylation and be a valuable compound to overcome TRAIL resistance in breast cancer cells.

A peroxisome proliferator-activated receptor-gamma agonist and other constituents from Chromolaena odorata.

Peroxisome proliferator-activated receptors (PPARs) are key regulators of lipid and glucose metabolism and have become important therapeutic targets for various diseases. The phytochemical investigation of the chloroform-soluble extract of Chromolaena odorata led to the isolation of a PPAR-gamma agonist, (9 S,13 R)-12-oxo-phytodienoic acid (1), together with 12 other compounds. The structures of chromomoric acid G (2), a new dehydrogenated derivative of 1, and chromolanone (3) were elucidated based on spectroscopic methods. Compound 1 showed a significant effect on PPAR-gamma activation in comparison with rosiglitazone. However, compound 2 was inactive, suggesting that the dehydrogenation of the prostaglandin-like structure in 1 abrogates its PPAR-gamma agonistic activity.

Hypoxia-inducible factor-1 inhibitory benzofurans and chalcone-derived diels-alder adducts from Morus species.

Hypoxia-inducible factor-1 (HIF-1) is the central mediator of cellular responses to low oxygen concentrations and vital to many aspects of cancer biology. Bioassay-guided fractionation of the chloroform-soluble extracts of Morus species using a hypoxia response element (HRE)-dependent reporter assay led to identification of six benzofurans (1-6) and two chalcone-derived Diels-Alder adducts (7, 8) from Mori Cortex Radicis and three prenylated benzofurans (9-11) and four chalcone-derived Diels-Alder adducts (12-15) from Morus bombycis. The structure of the new 2-arylbenzofuran-type compound, moracin Q (3), was elucidated by spectroscopic methods, and the absolute configuration of 2 was determined for the first time. The selected compounds (1-3, 5, 7, 9, 10, and 12) from the cell-based reporter assay were found to inhibit hypoxia-induced HIF-1alpha accumulation in a dose-dependent manner in human hepatocelluar carcinoma cell-line Hep3B cells. Furthermore, these compounds were also active against hypoxia-induced vascular endothelial growth factor (VEGF) secretion in Hep3B cells.

Phenolic constituents of Amorpha fruticosa that inhibit NF-kappaB activation and related gene expression.

NF-kappaB is known to play a crucial role in the regulation of genes controlling the immune system, apoptosis, tumor cell growth, and tissue differentiation. Bioassay-guided fractionation of the n-hexane-soluble fraction of a methanol extract of Amorpha fruticosa afforded four new compounds, 5, 7, 8, and 9, and eight known compounds. Their structures were elucidated by spectroscopic methods. All compounds inhibited NF-kappaB activity, and tephrosin (1), 11-hydroxytephrosin (2), and deguelin (3) were the most active, with IC50 values of 0.11, 0.19, and 0.22 microM, respectively, in TNF-alpha-stimulated HeLa cell-based reporter gene assays. Further investigations showed that compounds 1, 5, and 6 blocked NF-kappaB/DNA binding activity and suppressed the expression of NF-kappaB target genes.

Bisacurone inhibits adhesion of inflammatory monocytes or cancer cells to endothelial cells through down-regulation of VCAM-1 expression.

Bisacurone, one of the active compounds of the traditionally used indigenous herb Curcuma longa Linne (Zingiberaceae), has anti-oxidant, anti-inflammatory, and anti-metastatic activities. We studied how the level of vascular cell adhesion molecule-1 (VCAM-1), one of the key molecules in the development of atherosclerosis as well as carcinogenesis and metastasis, might be affected by bisacurone in tumor necrosis factor-alpha (TNF-alpha)-activated human umbilical vein endothelial cells (HUVECs). Bisacurone dose-dependently inhibited TNF-alpha-mediated expression of VCAM-1. It showed significant suppressive effect on ROS generation in response to TNF-alpha stimulation and it blocked nuclear factor-kappa B (NF-kappaB) p65 translocation into the nucleus and phosphorylation of inhibitory factor kappaBalpha (IkappaBalpha). It also inhibited phosphorylation of Akt and PKC, which are upstream in the regulation of VCAM-1 by TNF-alpha. Furthermore, bisacurone decreased U937 monocyte and human oral cancer cell (Hep-2, QLL-I, SCC-15) adhesion to HUVECs stimulated by TNF-alpha, suggesting that it may inhibit the binding of these cells by regulating the expression of critical adhesion molecules by TNF-alpha. Thus, bisacurone may be beneficial in the treatment of inflammatory diseases, such as atherosclerosis, where inflammatory monocytes are involved in their pathology, and, moreover, in the development of tumors.

A quassinoid 6alpha-tigloyloxychaparrinone inhibits hypoxia-inducible factor-1 pathway by inhibition of eukaryotic translation initiation factor 4E phosphorylation.

Hypoxia-inducible factor-1 (HIF-1) is the central mediator of cellular responses to low oxygen and vital to many aspects of cancer biology. In a search for HIF-1 inhibitors, we identified a quassinoid 6alpha-tigloyloxychaparrinone (TCN) as an inhibitor of HIF-1 activation from Ailantus altissima. We here demonstrated the effect of TCN on HIF-1 activation induced by hypoxia or CoCl2. TCN showed the potent inhibitory activity against HIF-1 activation induced by hypoxia in various human cancer cell lines. This compound markedly decreased the hypoxia-induced accumulation of HIF-1alpha protein dose-dependently, whereas it did not affect the expressions of HIF-1beta and topoisomerase-I. Furthermore, TCN prevented hypoxia-induced expression of HIF-1 target genes for vascular endothelial growth factor (VEGF) and erythropoietin. Further analysis revealed that TCN strongly inhibited HIF-1alpha protein synthesis, without affecting the expression level of HIF-1alpha mRNA or degradation of HIF-1alpha protein. Moreover, the levels of phosphorylation of extracellular signal-regulated kinase-1/2 (ERK1/2), mitogen-activated protein (MAP) kinase-interacting protein kinase-1 (MNK1) and eukaryotic initiation factor 4E (eIF4E) were significantly suppressed by the treatment of TCN, without changing the total levels of these proteins. Our data suggested that TCN may exhibit anticancer activity by inhibiting HIF-1alpha translation through the inhibition of eIF4E phosphorylation pathway and thus provide a novel mechanism for the anticancer activity of quassinoids. TCN could be a new HIF-1-targeted anticancer agent and be effective on mammalian target of rapamycin (mTOR)-targeted cancer therapy, in which mTOR inhibition increases eIF4E phosphorylation.

A new quinazolinedione alkaloid from the fruits of Evodia officinalis.

A new quinazolinedione alkaloid, wuchuyuamide IV (1) was isolated from the fruits of Evodia officinalis.1 showed moderate cytotoxicity against Hela and HT1080 cell lines.

Abietane diterpenes from Salvia miltiorrhiza inhibit the activation of hypoxia-inducible factor-1.

The hypoxia-inducible factor-1 (HIF-1) has been known to be correlated to the adaptation and proliferation of tumor cells; therefore HIF-1 has become an important target in the development of anticancer drugs. A phytochemical study of the CHCl3-soluble fraction of Salvia miltiorrhiza, which strongly inhibited hypoxia-induced reporter gene expression, led to the isolation of 12 abietane-type diterpenes. Of these compounds, sibiriquinone A (1), sibiriquinone B (2), cryptotanshinone (3), and dihydrotanshinone I (4) potently inhibited hypoxia-induced luciferase expression with IC50 values of 0.34, 3.36, 1.58, and 2.05 microM on AGS cells, a human gastric cancer cell line, and 0.28, 3.18, 1.36, and 2.29 microM on Hep3B cells, a human hepatocarcinoma cell line, respectively. Consistently, 1 and 4 dose-dependently suppressed the HIF-1alpha accumulation and 1 inhibited mRNA expression of vascular endothelial growth factor (VEGF) under hypoxia. These results suggest that the anticancer activity of tanshinones is likely at least in part associated with their inhibition of HIF-1 accumulation.

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.