Copper acetylides may be the intermediate of some carbon-carbon coupling reactions. Metal acetylides were studied extensively due to their variable coordination modes. In order to mimic the structure of the intermediate, we synthesized different thioaminophosphine copper(I) complexes and tested their reactivity toward alkynes in this thesis. We introduced steric effect by controlling the carbon-chain length between second and third donor atoms of ligands and electronic effect by altering substituent groups of pheneylacetylenes. Results showed that alkynylcopper complexes were dimmeric in which the two copper(I) centers were brideged by two £g2-£b1-acetylides. Since sulfur atom of thioaminophosphine ligand was not coordinated to copper center, there was no steric effect observed in alkynylcopper complexes. No significant structural difference among alkynylcopper complexes due to electronic effect was seen either. Finally we tested reactions of thioiminophosphine copper(I) complexes toward thiophenolate. The product was a dinuclear copper(I) complex brideged by a £g2-£b1-thiophenolate ligand. Both copper(I) centers were coordinated with phosphorus, nitrogen and sulfur atoms of thioiminophosphine ligand extremely distorted tetrahedron geometry.

We utilized the tripodal ligand (tris-(3,5-di-tert-butyl-2-hydroxy-phenyl)- phosphine) H3[O3P] to react with 1 equiv of AlR3 (R = Cl, Me, Et, iBu and OiPr). From NMR and X-ray data proved, we could give the stable Al(III) complexes [O3P-H]AlR (R = Cl, Me, Et and iBu). [O3P-H]AlR is a zwitterionic complexes. Because the phenolato phosphine ligand bond a proton at the phosphorous, and Al(III) coordinated three RO- (tris phenolate group) and one alkyl- substituent group. So the Al(III) metal could be carried -1 charge and the phosphorous could be carried +1 charge. When H3[O3P] reacted with AlR3, the original trisphenolato phosphine ligand ([O3P]3-) was changed into a trisphenoato phosphonium ligand ([O3P-H]2-). The [O3P-H]AlMe in the trisphenoato phosphonium group has a proton, and we attempted to use a bese to deprotonate the acidic proton. We chose n-BuLi to react with [O3P-H]AlMe, and successfully gave {[O3P:]AlMe}- ionic complexe. In the {[O3P:]AlMe}- complexe, the lone pair electron of phenolato phosphine group is a nucleophile,It reacted with MeOTf of electrophile. The product of the reaction could give [O3P-Me]AlMe.In this reactions, the original trisphenoato phosphonium ligand ([O3P-H]2-) was changed into a new methyl trisphenoato phosphonium ligand ([O3P-Me]2-). We could utilize H3[O3P] to react with 1 equiv MeOTf in diethyl ether, and gave a new tripodal ligand {H3[O3P-Me]}OTf. Also, we utilized the {H3[O3P-Me]}OTf to react with 1 equiv of AlR3 (R = Cl, Me, Et and iBu). We gave that Al(III) complexes [O3P-Me]AlR (R = Cl, Me, Et and iBu).

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Thèse de doctorat : Chimie et physicochimie des composés d'intérêt biologique : Orléans : 2009. Thèse de doctorat : Chimie et physicochimie des composés d'intérêt biologique : Université de Bacau : 2009. / Titre provenant de l'écran-titre.

Frankfurt (Main), Univ., Diss., 2004

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

A series of conformationally constrained and flexible pseudopeptides were prepared and their thermodynamic parameters on binding to the Grb2 SH2 domain were determined by isothermal titration calorimetry (ITC). Cyclopropane constrained analogs having hydrophobic amino acid residues at the pTyr+1 position exhibited, on average, a 2-5 fold improvement in binding affinities with the enhancement in affinities due to a more favorable enthalpy, not entropy, of binding. This serves as the first set of examples which demonstrate that favorable entropies of binding are not an inherent characteristic of ligand preorganization. Incorporation of polar amino acid residues at the pTyr+1 position eventuated in a slightly different thermodynamic effect than what was observed with the hydrophobic analogs. The constrained molecules exhibited greater binding affinities for the Grb2 SH2 domain and that increase in affinity was a consequence of a more favorable enthalpy, not entropy, of binding. However, the binding entropies for the polar set of constrained and flexible molecules were all negative. Structural information obtained from the co-crystallization of selected constrained and flexible ligand pairs with the Grb2 SH2 domain revealed an increase in conformational mobility of the BC loop in the complexes of the constrained derivatives and the presence of a greater number of direct polar contacts, but fewer water-mediated interactions between the phosphate group of the constrained molecules and the pTyr binding pocket of the domain. The construction of the cis-hydrindanone ring system in sieboldine A was accomplished utilizing either a Lewis acid-mediated silyl-directed Nazarov cyclization of a functionalized divinyl ketone or a sequential Ni(0)-catalyzed 1,4-addition/5-endo-dig cyclization. Propargylzinc bromide was shown to undergo conjugate addition to the [alpha]-aminopropyl substituted enone using Ni(acac)₂, thus providing a new, mild protocol for the conjugate propargylation reaction. Further efforts toward the formation of the α-epoxy ketone are described. / text

A great number of pharmaceutical drugs target nucleic acids. However, drug-DNA interactions can be region non-specific and lead to undesired side effects. Understanding the mechanisms that regulate drug-DNA binding can help in the design of potent and selective therapeutic agents with fewer deleterious side effects. The present investigation explores the metal-mediated DNA binding of a group of 2-(2-hydroxyphenyl)benzoxazole (HPB) ligands and the aggregation dependant G-quadruplex selectivity of a series of perylene tetracarboxylic acid diimides (PTCDI) compounds. HPB ligands are simplified analogs of the bis-benzoxazole natural product UK-1. This compound is able to inhibit cell growth of various tumor cell lines, bind divalent cations, and interact with DNA in a metal dependant fashion. The HPB moiety present in UK-1 was identified as relevant for its metal ion binding and biological properties. For this work, novel HPB ligands were synthesized with different substitutions at the C4 or C7 position. Their ability to bind metal ions and DNA was evaluated and their cytotoxicity was assessed in multiple cancer cell lines. The ligands bound to Cu²⁺ with the highest affinity among metals studied. Consequently, Cu²⁺ promoted the most dramatic increase in DNA binding and affected the ligand's cellular cytotoxicity. The second project focused on targeting four-stranded structures called G-quadruplexes, which can form in G-rich nucleic acid sequences. Compounds that stabilize these structures may inhibit nucleic acid-processing enzymes such as telomerase and potentially act as anti-cancer agents. PIPER is a PTCDI that is particularly selective for G-quadruplex DNA versus duplex DNA under conditions in which it forms aggregates. This work investigated ligand aggregation in a series of PIPER analogs with different structural features under high and low salt buffers, changes in pH, metal binding and temperature changes. A negatively charged analog was determined to form metal-mediated aggregates while novel thermophilic mediated aggregation was discovered for an analog with methoxyethoxymethyl groups. The ability of these ligands to bind different DNA structures was evaluated under aggregating and non-aggregating conditions. This study supports the idea that ligand aggregation increases their quadruplex selectivity and decreases double-stranded DNA binding.

Objectives: Periodontal disease is a chronic inflammation resulting in periodontal attachment loss. Keratinocyte Growth Factor-1 (KGF-1) is upregulated in chronic inflammation and specifically stimulates epithelial cell proliferation by signaling through the epithelial-specific Keratinocyte Growth Factor Receptor (KGFR). First, we examined KGF-1 and KGFR expression and localization in human periodontal tissues. Second, we extended these studies by developing an in vitro mechanical wound model to mimic trauma to the periodontal pocket epithelium and examined ligand independent KGFR activation and cell migration. Methods: In our study of human gingival tissues, we used immunohistochemistry and laser capture microdissection with RT-PCR to analyze KGF-1 and KGFR expression and localization. To study ligand independent KGFR phosphorylation, KGFR internalization along the wound edge was imaged using immunohistochemical staining and KGFR phosphorylation confirmed using immunoprecipitation with western blotting. Wounding induced oxidative stress was detected using DCFH-DA (2',7'-dichlorofluorescin diacetate) and modulated by pretreatment with an antioxidant. Changes in migration were examined in the presence or absence of pathway specific inhibitors. Results: KGF-1 protein localized to areas of junctional and basal oral epithelial cells was significantly increased in periodontal pocket epithelium (p<0.01) and oral epithelium (p<0.05) of disease-associated tissues. KGFR localized to the junctional and the parabasal cells of oral epithelium, and was increased in disease-associated pocket epithelium (p<0.05). Laser capture microdissection with RT-PCR confirmedKGF-1 and KGFR were specifically expressed by connective tissue and epithelium, respectively. In our cell culture model, mechanical wounding induced ligand independent KGFR activation. ROS (Reactive Oxygen Species) generation along the wound edge was associated with KGFR activation and scavenging of ROS reduced KGFR phosphorylation. The c-Src family inhibitor, PP1, significantly inhibited KGFR phosphorylation. Functionally cell migration was reduced by PP1 (82.7%), SU5402(70%) and PD98059 (57%). Conclusions: KGF-1 and KGFR proteins are expressed in health but significantly induced in human diseased periodontal tissues. Microwounding associated generation of ROS mediates KGFR phosphorylation via c-Src kinase signaling and induced wound edge cell migration. Therefore, regulation of epithelial cell behavior associated with the onset and progression of periodontal disease may possibly be mediated by two related but distinct mechanisms. (1) Ligand-dependent activation of KGFR due to upregulation of KGF-1. (2) Ligand-independent activation of KGFR due to chronic microwounding.

No description available.