Browsing by Author "Chen, Shui-Tein"

A new biflavonol glycoside, quercetin-3-O-β-D-glucopyranoside- (3'→O-3''')- quercetin-3-O-β-D-galactopyranoside (9), together with eight known compounds was isolated for the first time from the leaves of Machilus zuihoensis Hayata (Lauraceae). The structure of compound 9 was elucidated by various types of spectroscopic data analysis. Analysis of the biological activity assay found that compound 9 showed significant superoxide anion scavenging activity (IC 50 is 30.4 μM) and markedly suppressed LPS-induced high mobility group box 1 (HMGB-1) protein secretion in RAW264.7 cells. In addition, the HMGB-1 protein secretion was also inhibited by quercitrin (3), ethyl caffeate (6), and ethyl 3-O-caffeoylquinate (7) treatment. In the LPS-stimulated inducible nitric oxide synthase (iNOS) activation analysis, two known compounds, quercetin (1) and ethyl caffeate (6), were found to markedly suppress nitric oxide (NO) production (IC 50 value, 27.6 and 42.9 μM, respectively) in RAW264.7 cells. Additionally, it was determined that ethyl caffeate (6) down-regulated mRNA expressions of iNOS, IL-1β, and IL-10 in the LPS-treatment of RAW264.7 cells via a suppressed NF-κB pathway. These results suggested for the first time that the new compound 9 and other constituents isolated from M. zuihoensis have potential anti-inflammatory and superoxide anion scavenging effects. These constituents may be useful for treating various inflammatory diseases. ? 2011 by the authors; licensee MDPI, Basel, Switzerland.

The most severe form of dengue virus (DENV) infection is dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), which is accompanied by increased vascular permeability indicating that endothelial cells are the targets of DENV infection. However, molecular mechanisms underlying DENV replication in endothelial cells remained poorly understood. We therefore examined changes in subcellular proteomes of different cellular compartments (including cytosolic, membrane/organelle, nucleus, and cytoskeleton) of human endothelial (EA.hy926) cells upon DENV2 infection using a 2-DE-based proteomics approach followed by Q-TOF MS and MS/MS. A total of 35 altered proteins were identified in these subcellular locales, including an increase in the level of Alix (apoptosis-linked gene-2-interacting protein X) in the cytosolic fraction of DENV2-infected cells compared to mock control cells. Double immunofluorescence staining revealed colocalization of Alix with late endosomal lysobisphosphatidic acid (LBPA). This complex has been proposed to be involved in the export of DENV proteins from late endosomes to the cytoplasm. Subsequent functional study revealed that pretreatment with an anti-LBPA antibody prior to DENV challenge significantly reduced the level of viral envelope protein synthesis and DENV replication. Our data indicate that Alix plays a pivotal role in the early phase of DENV replication, particularly when it arrives at the late endosome stage. Blocking this step may lead to a novel therapeutic approach to reducing the level of DENV replication in vivo. ? 2010 American Chemical Society.

Background: MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression at the post-transcriptional level. Recent studies have suggested that miRNAs and transcription factors are primary metazoan gene regulators; however, the crosstalk between them still remains unclear.Methods: We proposed a novel model utilizing functional annotation information to identify significant coregulation between transcriptional and post-transcriptional layers. Based on this model, function-enriched coregulation relationships were discovered and combined into different kinds of functional coregulation networks.Results: We found that miRNAs may engage in a wider diversity of biological processes by coordinating with transcription factors, and this kind of cross-layer coregulation may have higher specificity than intra-layer coregulation. In addition, the coregulation networks reveal several types of network motifs, including feed-forward loops and massive upstream crosstalk. Finally, the expression patterns of these coregulation pairs in normal and tumour tissues were analyzed. Different coregulation types show unique expression correlation trends. More importantly, the disruption of coregulation may be associated with cancers.Conclusion: Our findings elucidate the combinatorial and cooperative properties of transcription factors and miRNAs regulation, and we proposes that the coordinated regulation may play an important role in many biological processes. ? 2011 Chen et al; licensee BioMed Central Ltd.

Background: Severe Acute Respiratory Syndrome (SARS) is a severe respiratory illness caused by a novel virus, the SARS coronavirus (SARS-CoV). 3C-like protease (3CLpro) of SARS-CoV plays a role in processing viral polypeptide precursors and is responsible of viral maturation. However, the function of 3CLproin host cells remains unknown. This study investigated how the 3CLproaffected the secretion of cytokines in the gene-transfected cells.Results: From immunofluorescence microscopy, the localization of c-myc tagged 3CLprowas detected both in the cytoplasm and nucleus of transfected A549 cells. Expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) was significantly decreased in 3CLpro-transfected cells by both RT-PCR and ELISA, but without changes in other cytokines, i.e., IL-1β, IL-6, IL-8, IL12p40, TNF-α, and TGF-β. Furthermore, the protein levels of NF-kB decreased in 3CLpro-transfected A549 cells when compared to EGFP transfected cells.Conclusions: Our results suggest that the 3CLpromay suppress expression of GM-CSF in transfected A549 cells through down-regulation of NF-kB production. ? 2011 Liao et al; licensee BioMed Central Ltd.

Honokiol (HNK) is a phenolic compound isolated from the bark of houpu (Magnolia officinalis), a plant widely used in traditional Chinese and Japanese medicine. While substantial evidence indicates that HNK possesses anti-inflammatory activity, its effect on dendritic cells (DCs) during the inflammatory reaction remains unclear. The present study investigates how HNK affects lipopolysaccharide (LPS)-stimulated human monocyte-derived DCs. Our experimental results show that HNK inhibits the inflammatory response of LPS-induced DCs by (1) suppressing the expression of CD11c, CD40, CD80, CD83, CD86, and MHC-II on LPS-activated DCs, (2) reducing the production of TNF-α, IL-1β, IL-6, and IL-12p70 but increasing the production of IL-10 and TGF-β1 by LPS-activated DCs, (3) inhibiting the LPS-induced DC-elicited allogeneic T-cell proliferation, and (4) shifting the LPS-induced DC-driven Th1 response toward a Th2 response. Further, our results show that HNK inhibits the phosphorylation levels of ERK1/2, p38, JNK1/2, IKKα, and IκBα in LPS-activated DCs. Collectively, the findings show that the anti-inflammatory actions of HNK on LPS-induced DCs are associated with the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. ? 2010 Wiley-Liss, Inc.

Chronic neurodegenerative disorders are having an increasing impact on public health as human longevity increases. Parkinson's disease (PD) is a degenerative disorder of the central nervous system and is characterized by motor system disorders resulting in loss of dopamine-producing brain cells. Pueraria thomsonii Benth. (Fabaceae) is an herbal medicine that has traditionally been used as an antipyretic agent. In the present study, the active constituents, daidzein and genistein, were isolated from P. thomsonii. Both compounds exhibited neurocytoprotective effects against 6-hydroxydopamine (6-OHDA)-induced cytotoxicity in nerve growth factor (NGF)-differentiated PC12 cells. Neither daidzein nor genistein affected 6-OHDA-induced cellular reactive oxygen species (ROS) generation according to flow cytometric analysis. Rather, they inhibited caspase-8 and partially inhibited caspase-3 activation, providing a protective mechanism against 6-OHDA-induced cytotoxicity in NGF-differentiated PC12 cells. The present results imply that daidzein and genistein may be useful in the development of future strategies for the treatment of PD. ? 2010 Elsevier Ltd. All rights reserved.

One-pot multicomponent synthesis to assemble compounds has been an efficient method for constructing a compound library. We have developed one-pot tandem copper-catalyzed azidation and CuAAC reactions that afford 1-thiazolyl-1,2,3-triazoles with anticancer activity. By utilizing this one-pot synthetic strategy, we constructed a library of 1-thiazolyl-1,2,3-triazoles in search of the potent lead compound. Furthermore, 1-thiazolyl-1,2,3-triazoles were evaluated for anticancer activity against the multidrug-resistant cancer cells MES-SA/Dx5. Most of the 1-thiazolyl-1,2,3-triazoles revealed cytotoxic effect against cancer cells at micromolar to low micromolar range. Testing some of the most potent compounds (5{4,2-4} and 5{5,1-3}) against the normal cell line Vero showed no significant toxicity (except 5{4,2}) to normal cells. This result indicates that compounds 5{4,3-4} and 5{5,1-3} possessed good potency and selectivity to cancer cells over normal cells. ? 2010 American Chemical Society.

Objectives: Common treatment of renal cell carcinoma associated with von Hippel-Lindau (VHL) disease is total (bilateral) or subtotal nephrectomy. Whereas total nephrectomy is associated with absolutely no residual renal function, subtotal nephrectomy frequently leads to chronic kidney disease (CKD) with some residual renal functions. However, molecular mechanisms underlying CKD remain unclear and the diagnosis of CKD is frequently accomplished at its late stage. Design and methods: We performed a plasma proteomics study to compare the plasma proteome profile of VHL patient who underwent total nephrectomy to the profiles of VHL patient with subtotal nephrectomy and healthy control. Totally 100?μg proteins from each sample was resolved by two-dimensional electrophoresis (2-DE) in triplicate and visualized with SYPRO Ruby fluorescence stain. Results: The normal plasma proteome profile markedly differed from the profiles of VHL patients. Comparative analysis between total versus subtotal nephrectomized patients revealed significant differences in levels of 20 plasma proteins. Pathway analysis revealed two important networks involving in lipid metabolism, molecular transport, carbohydrate metabolism, cellular growth and proliferation, and small molecule biochemistry, in which these identified and other proteins interplayed. Conclusions: Our data identified potential biomarkers for CKD. Further characterization of these identified proteins might also lead to better understanding of molecular mechanisms underlying CKD. ? 2009 The Canadian Society of Clinical Chemists.

β-amyloid (Aβ) plays a key role in the pathogenesis of Alzheimers disease (AD) by inducing neurotoxicity and cell death mainly through production of reactive oxygen species (ROS). Garcinia mangostana L. (mangosteen) has been recognized as a major source of natural antioxidants that could decrease ROS. However, its role in protection of Aβ-induced cytotoxicity and apoptosis in neuronal cells remains unclear. We therefore examined such a protective effect of mangosteen extract (ME) by evaluating cell viability using MTT test, ROS level, caspase-3 activity, and cellular proteome. Treating SK-N-SH cells with 5-20 μM Aβ(1-42) for 24 h caused morphologically cytotoxic changes, decreased cell viability and increased ROS level, whereas preincubation with 50-400 μg/mL ME 30 min before the induction by Aβ(1-42) successfully prevented such cytotoxic effects in a dose-dependent manner (completely at 400 μg/mL). The Aβ-induced increase in caspase-3 activity was also preventable by 400 μg/mL ME. Proteomic analysis using 2-D gel electrophoresis (n = 5 gels/group) followed by mass spectrometry revealed 63 proteins whose levels were significantly altered by Aβ(1-42) induction. Interestingly, changes in 10 proteins were successfully prevented by the ME pretreatment. In summary, we report herein the significant protective effects of ME against Aβ-induced cytotoxicity, increased ROS, and increased caspase activity in SK-N-SH cells. Moreover, proteomic analysis revealed some proteins that might be responsible for these protective effects by ME. Further characterizations of these proteins may lead to identification of novel therapeutic targets for successful prevention and/or decreasing the severity of AD. ? 2010 American Chemical Society.

Hepatitis B virus (HBV) X protein (HBx) plays a key role in the development of hepatocellular carcinoma (HCC) in HBV carriers. Adrug that can bind to the promoter region of HBV may shut down the expression of HBx and subsequently prevent the development of HCC in the HBV carrier. We have constructed a seven amino acid residue peptide library on a TentaGel resin using a combinatorial one-bead one-sequence peptide synthesis method. The fluorescently labeled eicosanucleotide (5'-(6-FAM) CTTTTGGGCT TTGCTGCCCC-3') of the HBx promoter region was used as a monitor to screen for peptides that have high binding affinity to the HBx promoter. Two heptapeptides, KAPLFSI and SRVRMTW, were identified, and synthesized. The binding affinities of the peptides to the HBx promoter oligonucleotide were determined using Surface Plasmon Resonance (SPR). The peptide KAPLFSI had a greater binding affinity constant (ka) and equilibrium constant (KD) than SRVRMTW. The ka and K D values with the full X-promoter sequence were found to be 1.425 E+5 (1/Ms) and 1.186 E-8 (M), respectively. The peptide may open a new route for tumor suppression in HBV carriers.

The preserved fungal species Antrodia camphorata has diverse health-promoting effects and has been popularly used in East Asia as a traditional herb. We isolated a volatile compound from the culture medium of A. camphorata and identified it as γ-dodecalactone (γ-DDL). Cytomic screening for immune-modulating activity revealed that γ-DDL can activate human NK cells to express the early activation marker CD69. Further experiments showed that γ-DDL not only can induce NK cells to express CD69 but also stimulate NK cells to secrete cytotoxic molecules (FasL and granzyme B) and Th1 cytokines (TNF-α and INF-γ). Measuring the distribution of γ-DDL in the subcellular compartments of NK cells revealed that γ-DDL has been converted to 4-hydroxydodecanoic acid (an acyclic isomer of γ-DDL) in a time-dependent manner in the cytoplasm. Synthetic (R,S)-4-hydroxydodecanoic acid activated NK cells to express CD69 mRNA within 10 min, in contrast to γ-DDL, which activated NK cells to express CD69 within 50 min. This faster activation suggests that γ-DDL has converted to 4-hydroxydodecanoic acid and to stimulate the NK cells to express CD69. Optically pure (R)-(+)-4-hydroxydodecanoic acid and (S)-(-)-4-hydroxydodecanoic acid were obtained via: (1) synthesis of its diastereomeric esters of (R,S)-4-hydroxydodecanoic (R)-(-)-2-phenylpropionate; (2) separation of diastereomers via preparative HPLC, and (3) subsequent hydrolysis of the obtained optical pure ester of (R)-(+)-4-hydroxydodecanoic acid (R)-(-)-2-phenylpropionate and (R)-(-)-4-hydroxydodecanoic acid (R)-(-)-2-phenylpropionate, respectively. Further assays of NK cells activation using each enantiomer showed that only the (R)-(+)-4-hydroxydodecanoic acid can activate NK cells. ? 2010 Elsevier Ltd. All rights reserved.