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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Chemical Constituents of the Formosan Soft Coral Nephthea chabrolii

Puu, Shyh-Yueh 10 September 2012 (has links)
Numerous bioactive secondary metabolites including sesquiterpenoids,diterpenoids, meroditerpenoids, and steroids have been isolated from the soft corals of the genus Nephthea. In order to search for novel bioactive substances from marine organisms, we have investigated the secondary metabolites of the organic extract of the soft coral Nephthea chabrolii collected at San-Hsian-Tai. Chromatographic fractionation of the acetone-soluble has led to the isolation of four 19-oxygenated steroids 1¡V4 and two 19-norergosterols 5, 6, along with twelve known compounds 7¡V18. The structures of these compounds were determined on the basis of their spectroscopic analysis data (1H NMR, 13C NMR, 1H¡V1H COSY, HSQC, HMBC, NOESY, IR, and HRESIMS), physical data and compared with the literature data. The cytotoxicity against of A-549 (human lung epithelial carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cells, and anti-HCMV (human cytomegalovirus) activity of compounds 1¡V6 were evaluated. Metabolites 1¡V6 displayed cytotoxicity against P-388 cell line with ED50 values of 0.93, 1.05, 1.20, 1.74, 1.19, 1.19 £gg/mL. However, none of them exhibited inhibitory activity against HCMV (human cytomegalovirus).
142

Studies on the Secondary Metabolites from the Formosan Soft Coral Sarcophyton ehrenbergi

Hsieh, Mu-Keng 11 September 2012 (has links)
In the course of studying on secondary metabolites from marine organisms, we have investigated the chemical constituents of the soft coral Sarcophyton ehrenbergi collected at San-Hsien-Tai, Taitong County, Taiwan. Chromatographic separation of the organic extracts has led to the isolation of nine new cembrane diterpenes 1¡V9, and a initial natural separation of known cembrane diterpene 10. The chemical structures of pure compounds were determined by spectral (NMR, MS, UV and IR) and physical data, as well as comparison with the spectroscopic data of related chemicals in literature. Moreover, the metabolites 1¡V10 were evaluated in vitro for their cytotoxicity against of A-549 (human lung epithelial carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cells, as well as anti-HCMV activity. Compounds 3, 6, 9, and 10 were shown to exhibit significant cytotoxicity activities against P-388 with ED50 values of 2.7, 3.6, 2.0, and 3.0 £gg/mL, respectively. Compound 1, 2, 3, and 7 exhibited inhibitory activity against anti-HCMV, with EC50 values of 60.0, 46.0, 5.0, and 45.0 £gg/mL.
143

Systematic Approach to Compare the Inflammatory Response of Liver Cell Culture Systems Exposed to Silver, Copper, and Nickel Nanoparticles

Banerjee, Nivedita 2010 August 1900 (has links)
Although nano-sized metal colloids are used in industrial and medicinal applications, little is known about the potential liver toxicity of these materials after occupational or intentional exposures. To begin to resolve some outstanding hepatotoxicity concerns, the inflammatory response of hepatocytes after exposure to metal colloids was assessed. Four ~30-nm-sized metal colloids, including silver (nano-Ag), copper (nano-Cu) and nickel (nano-Ni) were examined in an effort to understand the induced cytokine expression in a murine liver cell line (AML12). Here we also utilized another system, co-cultures of hepatocytes, Kupffer’s cells, and lymphocytes isolated from C57BL6 mice. Cells were exposed to the materials over dose-response (0.1mg/L to 1000mg/L) and time-dependent (4 h, 48 h, and 1-week) studies. Cytotoxicity was measured via metabolism of resazurin and validated via MTT assay and cell counts. Inflammatory response was determined by cytokine profiles (TNF-a and IL-6), as well as by mRNA and protein expression of heat shock protein (Hsp70). Results from cells exposed to nano-Ag to doses of up to 100mg/L exhibited no significant changes in cytotoxicity, IL-6, or TNF-a production, or Hsp70 expression. Both nano-Cu and nano-Ni exposed cells exhibited decreased metabolism, increased Hsp70 induction, and increased inflammatory responses (IL-6 and TNF-a). Dynamic light scattering and electron microscopy were used to characterize particle size and surface charge. All three metal colloidal systems demonstrated different particle size distributions, agglomerated sizes, and surface zeta potentials. Furthermore, each metal colloid system elicited different inflammatory biomarker responses and stress protein expression.
144

Chemical Constituents and Cytotoxicity of Soft Corals Sarcophyton crassocaule, Sarcophyton elegans and Sarcophyton trocheliophorum

Jung, Sheng-Ge 09 June 2000 (has links)
Chromatographic purification of a methylene chloride extract of Formosan soft coral Sarcophyton crassocaule (collected in Green island) led to the isolation of two new (1S*, 3R*, 4R*, 7E, 11E, 14R*)-3, 4-epoxycembra-7, 11, 15-trien-1, 14-olide (1) and (1R*, 3E, 7E,11R*, 12S*, 14R*)-11, 12-epoxycembra-3, 7, 15-trien-1, 14-olide (2) isomeric diterpenoids , a known cyclic peroxide diterpenoid (1R*, 2S*, 3E, 7S*, 8R*, 11S*, 12Z)-8, 11-epidioxy-7-acetoxycembra-3, 12, 15-trien-1, 2-olide (3), as well as two known (24S)-24-methylcholestane-3b, 5a, 6b-triol (4) and 24x-methyl-cholestane -3b, 5a, 6b, 25-tetrol 25-monoacetate (5) steroids. Chromatographic fractionation of a methylene chloride extract of two Formosan soft corals Sarcophyton elegans (collected in Green island) led to the isolation of a known 24x-methylcholestane -3b, 5a, 6b, 25-tetrol 25-monoacetate (5) steroid, the methylene chloride extract of Sarcophyton trocheliophorum, on the other hand, afforded a known diterpenoid, (+)-isosarcophine (6). Purification of a methylene chloride extract of Octocorallia soft coral (unidentified) led to the isolation of two known steroids, cholesterol (7) and (22E, 24S)-24-methylcholesta-5, 22-dien-3b-ol (8). Compounds 1-7 exhibited cytotoxicity against P388 cancer cell line. Compounds 2 and 5 were active against HT-29 cancer cell line.
145

Futher Studies on the Steroidal Natural Productsfrom the Formosan Gorgonian Isis hippuris

Huang, L.-F. 01 September 2002 (has links)
Abstract Several sesquiterpenes isolated from a Formosan gorgonian coral Isis hippuris have shown significant cytotoxic activity against various cancer cell lines. In order to search other active components, we have investigated the chemical constituent of I. hippuris from a Green Island specimen. In the cytotoxcity assay, the EtOAc extract showed potent cytotoxic response toward P-388, A549 and HT-29 cancer cell lines. Thus, the investigation on the chemical content of this extract was carried out. This study finally led to the isolation of twelve steroids(1-12). Nine metabolites, hippuristerone G (1)¡Bhippuristerone H (2), hippuristerone I (3)¡Bhippuristerone J (4)¡Bhippuristerol E (5)¡B2a,3a-diacetoxy-24-methyl- 11b,18; 18,20b; 22,25-triepoxy-5a-furostane (7)¡B2a,3a-diacetoxy-11b- hydroxy-24-methyl-22,25-epoxy-5a-furostan-18,20b-lactone (10)¡B3a- acetoxy-11b,18a-dihydroxy-24-methyl-18,20b; 22,25-diepoxy-5a- furostane (11) and 2a,3a-diacetoxy-11b,18a-dihydroxy-24-methyl-18, 20b; 22,25-diepoxy-5a-furostane (12) are new compounds, whereas hippuristerone A (6), 3a-acetoxy-24-methyl-11b,18; 18,20b; 22,25- triepoxy-5a-furostane (7) and 3a-acetoxy-11b-hydroxy-24-methyl-22,25- epoxy-5a-furostan-18,20b-lactone (9) are known compounds. The structures of 1-12 were elucidated by spectroscopic evidences (IR, MS, 1D NMR, 2D NMR) and chemical method. The stereochemistries of compounds 7 and 9 were further confirmed by single-crystal X-ray diffraction analyses. Cytotoxicity test revealed that hippuristerone I (3) exhibited moderate inhibition toward NCI cancer cell line.
146

The Assessment of an In-vitro Model for Evaluating the Role of PARP in Ethanol-mediated Hepatotoxicity

Coyle, Jayme 01 January 2013 (has links)
This investigation assesses the role of poly(ADP-ribose) polymerase in ethanol-mediated hepatotoxicity using the untransfected HepG2 hepatocellular carcinoma line, an established, well-characterized toxicological model. HepG2 cells were treated with ethanol at concentrations between 100 mM and 800 mM, and assessed for markers of cytotoxicity. PARP-1 activity in total cell protein lysates was quantified as a proxy of apoptotic induction at six hours. Our results demonstrated a 1.43-fold AST activity increase in culture medium isolates of cells exposed to 800 mM without significant effect on cellular viability. PARP-1 activity varied greatly and results for enzyme activity remained inconclusive. The results suggest a high degree of insensitivity to ethanol toxicity and nuclear enzyme activity, demonstrating the metabolic irrelevance of untransfected HepG2 in ethanol toxicosis. There is a need to characterize phase 1 metabolic enzyme expression profiles relevant to ethanol for CYP2E1 and ADH pathways to facilitate comparisons across toxicological models using transfected, as well as the untransfected HepG2 model.
147

Signaling in natural killer cells: SHIP, 2B4 and the Kinome

Wahle, Joseph A 01 June 2007 (has links)
The NK cell is a large granular lymphocyte that plays a key role in protecting the body against numerous pathogens including parasites, intracellular bacteria, viral infections, as well as showing anti-tumor activity and playing a role in the rejection of allogeneic BM. Unlike other lymphocytic cell types, that utilize rearranging receptors, NK cells are regulated by a complex array of germ line encoded activating and inhibitory receptors. NK cells are often described as a front line or rapid defense given their response to stimuli can be immediate, although they also maintain functions that extend their role well into the adaptive immune system. Inhibitory receptors that recognize MHC class I molecules regulate NK cell responses and self-tolerance. Recent evidence indicates self-ligands not present in the MHC locus can also modulate NK function. We previously demonstrated that the NK receptor repertoire is disrupted by SHIP-deficiency. Here we show that an inhibitory receptor, 2B4, that recognizes an MHC-independent ligand is over expressed in NK cells of SHIP-/- mice at all stages of NK development and differentiation. Overexpression of 2B4 compromises key cytolytic NK functions, including killing of allogeneic, tumor and viral targets. These results demonstrate that in SHIP-/- NK cell 2B4 is the dominant inhibitory receptor. We then furthered this finding by examining the molecular basis of 2B4 dominance. We show that in SHIP-/- NK cells there is increased 2B4 expression as well as a strong bias towards the 2B4L isoform. We have also identified a greater than tenfold increase in SHP1 recruitment to 2B4. Consistent with this SHP1 over recruitment,both a broad and a selective SHP1 inhibitor restore SHIP-/- NK killing of complex targets.Through this study we have identified the molecular mechanism of 2B4 receptor dominance as SHP1 over-recruitment.In addition we have utilized protein array technology to explore NK signaling through the determination of the NK kinome. To this end we have been able to identify multiple pathways that may mark crucial differences between the mature and immature NK cell.
148

Mechanisms of 11-deoxy-16, 16-dimethyl prostaglandin E₂ mediated cytoprotection

Jia, Zhe, 1976- 28 August 2008 (has links)
Not available / text
149

The role of oxidative stress in mediating the biological effects of Raman-silica-gold-nanoparticles

Thakor, Avnesh Sinh January 2012 (has links)
No description available.
150

Design, Synthesis, and Anticancer Activity of Ruthenium Complexes

Howerton, Brock S. 01 January 2012 (has links)
Ruthenium complexes show promise as light activated photodynamic therapy (PDT) prodrugs. Strained octahedral complexes were synthesized that produce a cytotoxic species upon light activation. pUC19 DNA damage in vitro experiments were carried out to determine the type of damage observed. In vivo cell experiments were carried out on the non-small lung cancer A549 cell line to determine the phototherapeutic window of the synthesized complexes. One mechanism of drug resistance via elevated levels of glutathione was addressed through in vitro binding studies carried out with UV-Vis spectroscopy and in vivo glutathione titrations in the A549 cell line. Several complexes were shown to be potential PDT agents with light-activated activities greater than cisplatin and 10-100 fold lower dark toxicities.

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