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- Title
- Cell-surface glycan-lectin interactions for biomedical applications.
- Creator
- Rodriguez Benavente, Maria Carolina, Lepore, Salvatore D., Cudic, Predrag, Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Carbohydrate recognition is one of the most sophisticated recognition processes in biological systems, mediating many important aspects of cell-cell recognition, such as inflammation, cell differentiation, and metastasis. Consequently, lectin-glycan interactions have been intensively studied in order to mimic their actions for potential bioanalytical and biomedical applications. Galectins, a class of ß-galactoside-specific animal lectins, have been strongly implicated in inflammation and...
Show moreCarbohydrate recognition is one of the most sophisticated recognition processes in biological systems, mediating many important aspects of cell-cell recognition, such as inflammation, cell differentiation, and metastasis. Consequently, lectin-glycan interactions have been intensively studied in order to mimic their actions for potential bioanalytical and biomedical applications. Galectins, a class of ß-galactoside-specific animal lectins, have been strongly implicated in inflammation and cancer. Galectin-3 is involved in carbohydrate-mediated metastatic cell heterotypic and homotypic adhesion via interaction with Thomsen-Friedenreich (TF) antigen on cancer-associated MUC1. However, the precise mechanism by which galectin-3 recognizes TF antigen is poorly understood. Our thermodynamic studies have shown that the presentation of the carbohydrate ligand by MUC1-based peptide scaffolds can have a major impact on recognition, and may facilitate the design of more potent and specific galectin-3 inhibitors that can be used as novel chemical tools in dissecting the precise role of galectin-3 in cancer and inflammatory diseases. Another lectin, odorranalectin (OL), has been recently identified from Odorrana grahami skin secretions as the smallest cyclic peptide lectin, has a particular selectivity for L-fucose and very low toxicity and immunogenicity, rendering OL an excellent candidate for drug delivery to targeted sites, such as: (1) tumor-associated fucosylated antigens implicated in the pathogenesis of several cancers, for overcoming the nonspecificity of most anticancer agents; (2) the olfactory epithelium of nasal mucosa for enhanced delivery of peptide-based drugs to the brain.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00004405
- Subject Headings
- Biopharmaceutics, Carbohydrates -- Therapeutic use, Cell differentiation, Drug delivery systems, Glycoproteins, Glycoslation, Mice as laboratory animals, Peptides -- Derivatives, Pharmaceutical biotechnology
- Format
- Document (PDF)
- Title
- Raman micro-spectroscopy and multivariate analysis for the differentiation of skin cancers.
- Creator
- Fox, Sara A., Terentis, Andrew C., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Skin cancer is a growing health concern worldwide. In this work, confocal Raman micro-spectroscopy (CRM) was combined with two types of multivariate analysis, principal component analysis (PCA) and linear discriminant analysis (LDA), to accurately differentiate between skin cancer and normal skin. CRM was employed to study three distinct intracellular regions – cytoplasm, nucleoplasm, and nucleolus – within human metastatic melanoma (SK) and skin fibroblast (BJ) cells. PCA/LDA was 92-98%...
Show moreSkin cancer is a growing health concern worldwide. In this work, confocal Raman micro-spectroscopy (CRM) was combined with two types of multivariate analysis, principal component analysis (PCA) and linear discriminant analysis (LDA), to accurately differentiate between skin cancer and normal skin. CRM was employed to study three distinct intracellular regions – cytoplasm, nucleoplasm, and nucleolus – within human metastatic melanoma (SK) and skin fibroblast (BJ) cells. PCA/LDA was 92-98% successful in discriminating BJ from SK cells, with higher RNA identified in the nucleoli of BJ cells and higher lipids and collagen identified in the cytoplasm of SK cells. CRM measurements were also done on SCC, BCC, and normal skin tissue samples to determine the feasibility of combining Raman spectroscopy with CO2 ablation. Differentiation with PCA was possible between normal and SCC tissue that had been ablated, with 78% correct identification when non-ablated and 92% when ablated.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fau/fd/FA00004247
- Format
- Document (PDF)
- Title
- Toward lanthanide containing coordination polymers and nanomaterials.
- Creator
- Greig, Natalie E., De Lill, Daniel T., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
The focus of this thesis is to develop lanthanide (Ln) luminescent materials through the exploration of coordination polymers and nanomaterials. Herein, dimethyl-3,4- furanedicarboxylate acid undergoes hydrolysis under hydrothermal conditions to form coordination polymers with lanthanide ions. The resulting coordination polymers exhibited luminescent properties, with quantum yields and lifetimes for the Eu-and Tb-CP of 1.14+-0.32% and 0.387=-0.0001 mx, and 3.33=-0.82% and 0.769=-0.006 ms,...
Show moreThe focus of this thesis is to develop lanthanide (Ln) luminescent materials through the exploration of coordination polymers and nanomaterials. Herein, dimethyl-3,4- furanedicarboxylate acid undergoes hydrolysis under hydrothermal conditions to form coordination polymers with lanthanide ions. The resulting coordination polymers exhibited luminescent properties, with quantum yields and lifetimes for the Eu-and Tb-CP of 1.14+-0.32% and 0.387=-0.0001 mx, and 3.33=-0.82% and 0.769=-0.006 ms, respectively. While the incorporation of lanthanides was not achieved in this work, progress toward the production of pure phase InP in the nanoregime has been made, using a low-cost, hydrothermal method. Through SEM and PXRD conflict, it is believed that pure INP particles with a size range of 58-81 nm were successfully synthesized.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3358558
- Subject Headings
- Metallic composites, Speciation, Lanthanide shift reagents, Rare earth metals catalysts, Nanostructured materials
- Format
- Document (PDF)
- Title
- Therapeutic potential, mechanism of action, and ecology of novel marine natural products.
- Creator
- Winder, Priscilla L., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
The projects described in this dissertation are focused on compounds derived from the marine environment. Chapter 1 gives an introduction to the study of marine natural products to treat human ailments and a thorough review on compounds from lithistid sponges that have been isolated or synthesized since 2000. Chapter 2 describes the isolation and structure elucidation of two sesquiterpene substituted benzoquinone derivatives, petrosiquinones A and B, from a deep-water marine sponge from the...
Show moreThe projects described in this dissertation are focused on compounds derived from the marine environment. Chapter 1 gives an introduction to the study of marine natural products to treat human ailments and a thorough review on compounds from lithistid sponges that have been isolated or synthesized since 2000. Chapter 2 describes the isolation and structure elucidation of two sesquiterpene substituted benzoquinone derivatives, petrosiquinones A and B, from a deep-water marine sponge from the Family Petrosiidae. Although initially purified following activity in a (Sb(B-catenin/Tcf4 assay they were later followed using tumor cell line cytotoxicity assays. Petrosiquinone A was the more active of the two compounds with moderate cytotoxicity in the DLD-1, PANC-1, and AsPC-1 cell lines. In Chapter 3, the isolation and structure elucidation of two new marine-derived macrolides, madeirolide A and B, isolated from a deep-water lithistid sponge of the genus Leiodermatium is described., They were isolated using numerous chromatographic techniques and the structures were elucidated on the basis of 1D and 2D NMR spectra coupled with high resolution-mass spectrometry (HR-MS) data. Madeirolide A and B inhibited the growth of the fungal pathogen Candida albicans with minimum inhibitory concentrations (MIC) of 12.5 and 25 (So(Bg/mL, respectively, but were not cytotoxic in tumor cell assays under the conditions tested. Chapter 4 describes work performed to determine the molecular target of lasonolide A using affinity chromatography. The target of lasonolide A is of interest since lasonolide A is known to kill cancer cells in vitro through a unique mechanism., This chapter highlights the research performed to create an affinity matrix with immobilized lasonolide. A target has not been confirmed but there are a number of interesting hits that are being pursued. In Chapter 5, a liquid chromatography-mass spectrometry (LC-MS) screening method was established in order to rapidly identify the metabolites from numerous collections of Lyngbya spp. obtained from Broward and Lee County, Florida sites that may help marine ecologists assess the effects of Lyngbya spp. blooms on the environment. A link between the metabolites produced and nutrients from both the algal tissue and water column was also explored.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/369392
- Subject Headings
- Natural products, Therapeutic use, Sponges, Ecology, Marine resources, Research, Marine biotechnology
- Format
- Document (PDF)
- Title
- Toward the synthesis of organic moieties for use in luminescent lanthanide materials: from benzodithiophene based linkers to a series of 2,3 pyridinedicarboxylate coordination polymers.
- Creator
- Ramirez, Amanda Lyn Staggers., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
The main focus of this thesis is to present the structural and photophysical characteristics of the coordination polymers [Ln(C7H3NO4)(C7H4NO4)(H2O)]n (Ln is Pr, Nd, Sm, Eu, and Tb), as well as attempting to synthesize the novel organic linker 4,4'(4,8-Dihydrobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)dibenzoic acid (BDTDC). Various lanthanide salts were coordinated with 2,3-pyridinecarboxylate (2,3- pydc) via hydrothermal synthesis. ... Progress was made toward the synthesis of a novel metal...
Show moreThe main focus of this thesis is to present the structural and photophysical characteristics of the coordination polymers [Ln(C7H3NO4)(C7H4NO4)(H2O)]n (Ln is Pr, Nd, Sm, Eu, and Tb), as well as attempting to synthesize the novel organic linker 4,4'(4,8-Dihydrobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)dibenzoic acid (BDTDC). Various lanthanide salts were coordinated with 2,3-pyridinecarboxylate (2,3- pydc) via hydrothermal synthesis. ... Progress was made toward the synthesis of a novel metal-organic framework linker BDTDC. Synthesis of the intermediate benzo[1,2-b:4,5-b']dithiophene as well as the determination of the crystal structure, were performed successfully and are reported herein.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362561
- Subject Headings
- Metathesis (Chemistry), Supramolecular chemistry, Organic compounds, Synthesis, Macromolecules, Synthesis
- Format
- Document (PDF)
- Title
- Synthesis and photophysical measurements of a series of lanthanide-benzenedicarboxylate coordination polymers.
- Creator
- Clark, Jessica Montressa., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Within solid-state chemistry, coordination polymers have gained interest for use in various applications such as sensing, catalysis, display technology, hydrogen storage, etc. The use of lanthanide ions in these materials provides a mean of exploring how structure may affect luminescence efficiency. In this study, the photophysics of several lanthanide benzenecarboxylates was studied. This data combined with data from other coordination polymers created in our lab indicate that the...
Show moreWithin solid-state chemistry, coordination polymers have gained interest for use in various applications such as sensing, catalysis, display technology, hydrogen storage, etc. The use of lanthanide ions in these materials provides a mean of exploring how structure may affect luminescence efficiency. In this study, the photophysics of several lanthanide benzenecarboxylates was studied. This data combined with data from other coordination polymers created in our lab indicate that the established guidelines for producing highly efficient materials may not correlate directly from solution to the solid state and that structure may also play a role.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362332
- Subject Headings
- Rare earth metals catalysts, Metallic composites, Speciation, Lanthanide shift reagents, Organic compounds, Synthesis, Polymers, Biotechnology
- Format
- Document (PDF)
- Title
- Neuroprotection from induced glutamate excitotoxicity by Conus brunneus conopeptides in a stroke-related model.
- Creator
- Crouch, Rebecca A., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Cone snails are carnivorous marine mollusks, utilizing their neuropeptide-rich venom for prey capture. The venom of Conus brunneus, a wide-spread Eastern Pacific vermivore, has not been extensively studied. In the current work, peptides from the dissected venom were characterized and tested using preliminary bioassays. Six peptides (A-F) were isolated and tested. Three peptide identities were determined by comparison with previously reported data: bru9a (A), bru3a (F), and an a-conotoxin (E)....
Show moreCone snails are carnivorous marine mollusks, utilizing their neuropeptide-rich venom for prey capture. The venom of Conus brunneus, a wide-spread Eastern Pacific vermivore, has not been extensively studied. In the current work, peptides from the dissected venom were characterized and tested using preliminary bioassays. Six peptides (A-F) were isolated and tested. Three peptide identities were determined by comparison with previously reported data: bru9a (A), bru3a (F), and an a-conotoxin (E). Preliminary screening in a stroke-related model of induced glutamate excitotoxicity in primary neuronal cells and PC12 cell cultures indicated potential neuroprotective activity of peptide fractions A, D, and F. Further testing is necessary to determine and verify structure, activity, target, and mechanism of action of the promising peptides from C. brunneus, which may prove effective neuropharmacological agents to treat stroke.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362331
- Subject Headings
- Gastropoda, Venom, Therapeutic use, Peptides, Structure, Neuroprotective agents, Central nervous system, Diseases, Treatment
- Format
- Document (PDF)
- Title
- Isolation of briareolate esters from Briareum asbestinum.
- Creator
- Meginley, Rian J., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
The gorgonian Briareum asbestinum is widely studied because it possesses highly oxygenated novel structures, many of which exhibit useful biological activities. Recently, two new briarane diterpenoids, briareolate esters J and K, together with two known briareolate esters have been isolated from a specimen of Briareum asbestinum collected off the coast of Boca Raton, Florida. The method used was a 96-well plate real-time cell electronic sensing (RT-CES) system to discover compounds that...
Show moreThe gorgonian Briareum asbestinum is widely studied because it possesses highly oxygenated novel structures, many of which exhibit useful biological activities. Recently, two new briarane diterpenoids, briareolate esters J and K, together with two known briareolate esters have been isolated from a specimen of Briareum asbestinum collected off the coast of Boca Raton, Florida. The method used was a 96-well plate real-time cell electronic sensing (RT-CES) system to discover compounds that impact human embryonic stem cell growth. The compounds were isolated using reversed phase polystyrene divinylbenzene chromatographic support HP20ss followed by normal phased HPLC using a luna silica column. The structures of the compounds were established though the interpretation of spectroscopic data. Activity testing was conducted against hESCs (BG02) with briareolate ester J showing no inhibition activity and briareolate ester K showing mild activity with an EC50 value of 25 (So(BM. These results confirm that the exact confirmation and existence of the (E,Z)-dienone is related to the activity that was observed with the previously isolated briareolate esters L and M.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3360959
- Subject Headings
- Coral reef ecology, Marine organisms, Environmental aspects, Marine natural products, Bioactive compounds
- Format
- Document (PDF)
- Title
- Cyclic lipodepsipeptides as lead structures for the discovery of new antiobiotics.
- Creator
- Bionda, Nina., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
With antimicrobial resistance to current drugs steadily rising, the development of new antibiotics with novel mechanisms of action has become an imperative. The majority of life-threatening infections worldwide are caused by "ESKAPE" pathogens which are encountered in more than 40% of hospital-acquired infections, and are resistant to the majority of commonly used antibiotics. Naturally occurring cyclic depsipeptides, microbial secondary metabolites that contain one or more ester bonds in...
Show moreWith antimicrobial resistance to current drugs steadily rising, the development of new antibiotics with novel mechanisms of action has become an imperative. The majority of life-threatening infections worldwide are caused by "ESKAPE" pathogens which are encountered in more than 40% of hospital-acquired infections, and are resistant to the majority of commonly used antibiotics. Naturally occurring cyclic depsipeptides, microbial secondary metabolites that contain one or more ester bonds in addition to amide bonds, have emerged as an important source of pharmacologically active compounds or lead structures for the development of novel antibiotics. Some of those peptides are either already marketed (daptomycin) or in advanced stages of clinical development (ramoplanin). Structurally simple, yet potent, fusaricidin/LI-F and lysobactin families of naturally occurring antibiotics represent particularly attractive candidates for the development of new antibacterial agents capable of overco ming infections caused by multidrug-resistant bacteria. These natural products exhibit potent antimicrobial activity against a variety of clinically relevant fungi and Gram-positive bacteria. Therefore, access to these classes of natural products and their synthetic analogs, combined with elucidation of their mode of action represent important initial steps toward full exploitation of their antmicrobial potential. This dissertation describes a general approach toward the solid-phase synthesis of fusaricidin/LI-F and lysobactin analogs and an extensive structure-activity relationship (SAR) study. We have devised a simple and robust preparation strategy based on standard Fmoc solid-phase peptide synthesis protocols., The SAR study revealed key structural requirements for fusaricidin/LI-F and related cyclic lipopeptides antibacterial activity, including the presence of the guanidino moietly at the end of the lipidic tail, hydrophobic amino acid residues, and peptide conformation Moreover, substitution of the ester bond with an amide bond significantly improved stability under physiologically relevant conditions and reduced toxicity. In addition, we have shown that these antibacterial peptides exert their mode of action via a novel mechanism, which invloves bacterial membrane interactions, followed by peptide internalization. Altogether, the research described in this dissertation demonstrates that new antibiotics derived from fusaricidin/LI-F natural products, have the potential to meet the challenge of antibiotic resistance in Gram-positive bacteria.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/FAU/3360768
- Subject Headings
- Microbial peptides, Drugs, Design, Peptides, Therapeutic use, Genetic engineering, Antibacterial agents, Peptide antibiotics, Research, Methodology, Peptide antibiotics, Analysis
- Format
- Document (PDF)
- Title
- Aggregation kinetics of A\U+fffd\ peptides and the inhibition effects of small molecules on A\U+fffd\ peptide aggregation.
- Creator
- Hijazi, Ahmad Alex., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
The pathology of Alzheimer's disease (AD) remains elusive. Competing evidence links amylois \U+fffd\-peptide (A\U+fffd\) amyloid formation to the phenotype of AD (1). The mechanism of amyloid fibril formation has been an ongoing investigation for many years. A\U+fffd\10-23 peptide, a fragment of A\U+fffd\1-42 peptide, contained crucial hydrophobic core residues (2). In this study, an investigation was launched to study the aggreagation process of A\U+fffd\1023 peptide and its ability to form...
Show moreThe pathology of Alzheimer's disease (AD) remains elusive. Competing evidence links amylois \U+fffd\-peptide (A\U+fffd\) amyloid formation to the phenotype of AD (1). The mechanism of amyloid fibril formation has been an ongoing investigation for many years. A\U+fffd\10-23 peptide, a fragment of A\U+fffd\1-42 peptide, contained crucial hydrophobic core residues (2). In this study, an investigation was launched to study the aggreagation process of A\U+fffd\1023 peptide and its ability to form amyloid fibrils. Furthermore, the presence of its hydrophobic core showed importance for its ability to aggregate and form amyloid fibrils. Thereafter, the inhibition of A\U+fffd\1-42 peptide aggregation was studied by using pyrimidine-based compounds. A\U+fffd\1-42 peptides, known to be neurotoxic, aggregate to form amyloid fibrils (3). This investigation may provide insight into the development of novel small molecular candidates to treat AD.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3358550
- Subject Headings
- Amyloid beta-protein, Proteins, Metabolism, Disorders, Prions, Alzheimer's disease
- Format
- Document (PDF)
- Title
- The chemistry of Briareum asbestinum.
- Creator
- Rondeau, Melody D., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Briareum asbestinum, a soft coral, is a rich source of diterpenoid natural products. The secondary metabolites of B. asbestinum fall into four classes : asbestinins, briarellins, briareolate esters, and briaranes. Briareolate esters have been shown to possess biological activity and were previously only reported from Tobago. Our group recently isolated briareolate esters from a specimen collected off the coast of Boca Raton, Florida. To determine whether location has an impact on the...
Show moreBriareum asbestinum, a soft coral, is a rich source of diterpenoid natural products. The secondary metabolites of B. asbestinum fall into four classes : asbestinins, briarellins, briareolate esters, and briaranes. Briareolate esters have been shown to possess biological activity and were previously only reported from Tobago. Our group recently isolated briareolate esters from a specimen collected off the coast of Boca Raton, Florida. To determine whether location has an impact on the chemistry produced by the organism, a method to discern between chemotypes was sought. Several techniques including thin layer chromatography (TLC), high performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and sclerite analysis were employed, with NMR being the most successful method. By utilizing both 1H and COSY NMR experiments, it is possible to differentiate between the chemotypes of B. asbestinum. Application of this method allowed analysis of chemical variability with respect to location.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3355882
- Subject Headings
- Heterocyclic compounds, Synthesis, Coral reef ecology, Marine organisms, Environmental aspects, Biochemical markers
- Format
- Document (PDF)
- Title
- An extraction optimization and determination of the absolute configuartion of clathric acid.
- Creator
- Rueda de Leon, Rolando, Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Current research in natural products has heavily focused on the identification of potent biologically active compounds, specifically for drug development. The project detailed in this thesis focuses on the extraction of compounds from marine invertebrates as well as defining the absolute configuration for a compound. Utilizing marine invertebrates, the sonications method developed in this thesis provides an alternative approach to rapidly extract compounds for primary screening. This method...
Show moreCurrent research in natural products has heavily focused on the identification of potent biologically active compounds, specifically for drug development. The project detailed in this thesis focuses on the extraction of compounds from marine invertebrates as well as defining the absolute configuration for a compound. Utilizing marine invertebrates, the sonications method developed in this thesis provides an alternative approach to rapidly extract compounds for primary screening. This method is viable compared to a traditional overnight extraction method, without suffering compound degredation... Previously, clathric acid was isolated from an unknown Clathria sp. This compound is a bibyblic C-21 terpenoid shown to have mild antimicrobial activity against gram positive bacteria. With only its relative configuration established, additional amounts of clathric acid were required to define the overall absolute configuration. Identifying the Clathria sp. to be Clathria compressa, through spicule analysis, additional sponge tissues were then collected off the coast of Boca Raton, Florida to isolate additional quatities of clathric acid. The absolulte configuration was determined through circular dichroism and the octant rule to establish a final configuration for clathric acid's four carbon stereocenters to be: (3S, 7S, 8R, and 12S).
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3355874
- Subject Headings
- Organic compounds, Analysis, Extraction (Chemistry), Natural products, Therapeutic use, Marine biotechology, Marine resources, Research, Sponges, Ecology
- Format
- Document (PDF)
- Title
- Mechanism of neuroprotection in stroke-related models.
- Creator
- Pan, Chunliu., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Stroke is the third leading cause of mortality in the United States, and so far, no clinical interventions have been proved truly effective in stroke treatment. Stroke my result in hypoxia, glutamate release and oxidative stress, etc. The purpose of this dissertation study is to evaluate the neuroprotective effects of four drugs (taurine, G-CSF sulindac and DETC-MeSO) on PC12 cell line or primary cortical neuronal cell culture, and to understand the protective mechanisms underlying in three...
Show moreStroke is the third leading cause of mortality in the United States, and so far, no clinical interventions have been proved truly effective in stroke treatment. Stroke my result in hypoxia, glutamate release and oxidative stress, etc. The purpose of this dissertation study is to evaluate the neuroprotective effects of four drugs (taurine, G-CSF sulindac and DETC-MeSO) on PC12 cell line or primary cortical neuronal cell culture, and to understand the protective mechanisms underlying in three stroke-related models : hypoxia, excessive glutamtate and oxidative stress. In the first part of this dissertation, we studied the neuroprotection of taurine against oxidative stress induced by H2O2 in PC12 cells. Our results show that extracellular taurine exerts a neuroprotective function by restoring the expression of Bcl-2 and downregulation of the three Endoplasmic Reticulum (ER) stress markers : GRP78, Bim and CHOP/GADD153, suggesting that ER stress can be provoked by oxidative stress and can be suppressed by taurine. In the second part, glutamate excitotoxicity-induced ER stress was studied with dose and time as variables in primary cortical neurons. The results demonstrate that glutamate excitotoxicity leads to the activation of three ER stress pathways (PERK, ATF6 and IRE1) by initiating PERK first, ATF6 second and IRE1 pathway last. The third part of this dissertation studied the robust and beneficial protection of taurine in cortical neurons under hypoxia/reoxygenation or glutamate toxicity condition. We found that taurine suppresses the up-regulation of GRP778, Bim, caspase-12 and GADD153/CHOP induced by excessive glutamate or hypoxia/reoxygenation, suggesting that taurine may exert a protective function against hypoxia/regeneration by reducing the ER stress., Moreover, taurine can down-regulate the ratio of cleaved ATF6 and full length ATF6, and p-IRE1 expresssion, indicating that taurine inhibits the ER stress induced by hypoxia/reoxygenation or glutamate through suppressing ATF6 and IRE1 pathways. In the fourth part, the synergistic benefits of the combination of taurine and G-CSF, and the neuroprotective effects of G-CSF, sulindac or DETC-MeSO are studied in cortical neurons. Our results show that G-CSF, sulindac or DETC-MeSO can highly increase the neuron visibility by inhibiting ER stress induced by hypoxia/reoxygenation or glutamate toxicity. Furthermore, we proved that G-CSF or sulindac can significantly inhibit the activation of ATF6 or IRE1 pathway stimulated by hypoxia/reoxygenation, and DETC-MeSO can suppress the activation of both PERK and IRE1 pathways in primary neuron cultures. These findings provide promising and rational strategies for stroke therapy.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3352284
- Subject Headings
- Sulindac, Physiological effect, Taurine, Physiological effect, Cerebral ischemia, Prevention, Biochemical markers, Diagnostic use, Apoptosis, Oxidation reduction reaction
- Format
- Document (PDF)
- Title
- Study of cell penetrating peptides with Raman spectroscopy and microscopy.
- Creator
- Ye, Jing., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
Cell penetrating peptides (CPPs) have drawn the attention of researchers due to their ability to internalize large cargos into cells including cancer cells. The mechanism(s) with which the peptides enter the cell, however, is/are not clear and full of controversy. The peptide conformations and their microenvironment in live cells had been unknown until the development of a technique developed in our lab. As a first demonstration of principle, penetratin, a 16-residue CPP derived from the...
Show moreCell penetrating peptides (CPPs) have drawn the attention of researchers due to their ability to internalize large cargos into cells including cancer cells. The mechanism(s) with which the peptides enter the cell, however, is/are not clear and full of controversy. The peptide conformations and their microenvironment in live cells had been unknown until the development of a technique developed in our lab. As a first demonstration of principle, penetratin, a 16-residue CPP derived from the Antennapedia homeodomain protein of Drosophila, was measured in single, living melanoma cells. Carbon-13 labeling of the Phe residue of penetratin was used to shift the intense aromatic ring-breathing vibrational mode from 1003 to 967 cm-1, thereby enabling the peptide to be traced in cells. Difference spectroscopy and principal components analysis (PCA) were used independently to resolve the Raman spectrum of the peptide from the background cellular Raman signals., On the basis of the position of the amide I vibrational band in the Raman spectra, the secondary structure of the peptide was found to be mainly random coil and b-strand in the cytoplasm, and possibly assembling as b-sheets in the nucleus. Next, label-free transportan was studied with the same methodology. The peptide, besides predominantly a-helix, adopted a significant portion of b-sheet conformation in the cytoplasm and nucleolus, which is different from the peptide in aqueous solution. The peptide microenvironment was also probed through H-bonding reported by the tyrosine Fermi doublet. Transportan displayed a tendency to accumulate in the cytoplasm over time which was unlike penetratin, which concentrated in the nucleus. The relative concentration of CPPs in various locations of live melanoma cells was directly estimated from the Raman spectra using average Phe concentration in the cell as an internal standard., The rapid entry and almost uniform cellular distribution of both peptides, as well as the lack of correlation between peptide and lipid Raman signatures, indicated that the mechanism of CPP internalization under the conditions of study was probably non-endocytotic. Last, transportan and penetratin were studied using polarized Raman spectroscopy for more detailed vibrational spectroscopic information of the two peptides in water and TFE solutions. The majority of the bands in the Raman spectra of the peptides were highly polarized, consistent with the high symmetry of aromatic ring side chain vibrational bands dispersed throughout the spectra. This work has provided new insights into the structure of CPPs in live cells and in solutions.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3342344
- Subject Headings
- Peptides, Analysis, Infrared spectroscopy, Raman spectroscopy, Cellular signal transduction
- Format
- Document (PDF)
- Title
- Molecular characterization of the injected venom of Conus ermineus.
- Creator
- Rivera-Ortiz, Jose A., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
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Cone snails are predatory marine animals that rely on their venom components to immobilize and capture their prey. According to the type of prey preference, cone snails can be divided into three groups: vermivorous, molluscivorous and piscivorous. Conus ermineus had been identified as the only piscivorous snail of the Atlantic Ocean. Cone snail venom is a complex and rich sources of natural toxins. The majority of the components of the venom are peptidic in nature, and they act over different...
Show moreCone snails are predatory marine animals that rely on their venom components to immobilize and capture their prey. According to the type of prey preference, cone snails can be divided into three groups: vermivorous, molluscivorous and piscivorous. Conus ermineus had been identified as the only piscivorous snail of the Atlantic Ocean. Cone snail venom is a complex and rich sources of natural toxins. The majority of the components of the venom are peptidic in nature, and they act over different ionic channels and membrane receptors. Initial studies using mixture of venom collected from dissected venom ducts concluded that the venom from the same species do not exhibit unusual peptide polymorphism [Olivera, Hillyard, et al., 1995] and that the only major difference between individuals of the same species are different concentrations of the venom components [Vianna, et al., 2005]. For this study, peptides in the injected venom were collected from individual snails and characterized usin g analytical RP-HPLC for a maximum of three years. The different fractions collected were processed through capillary HPLC coupled with Q-TOF ESI-MS, and compared with analytical RP-HPLC fractions processed with MALDI-TOF MS. This study demonstrates that there is an animal-to-animal variation in the peptide components of the injected venom. The injected venom remains relatively constant over time for specific specimens in captivity. Finally, there are some peptides that had been found in all specimens both by MALDI-TOF MS and by ESI-MS. In this study, these peptides are called "molecular fingerprint" peptides. Based on matches of their derived masses to those predicted by published cDNA sequences, nine novel peptides were putatively identified. This study establishes that variations due to enzymatic posttranslational modification are omitted when we consider only information extrapolated from cDNA., The results of this study support the idea of the existence of a novel regulatory mechaism to expressed specific venom peptides for injection into the prey.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3333310
- Subject Headings
- Gastropoda, Venom, Peptides, Structure, Coastal ecology
- Format
- Document (PDF)
- Title
- Synthesis and new reactions of allenyl carbonyls: studies towards the total synthesis of anti-thrombotic natural products Vitisinol D and C.
- Creator
- Maity, Pradip., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
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We report here the development of new and more general synthetic pathways for the preparation of allenyl and alkynyl carbonyls. These highly dense functionalized compounds were utilized as key intermediates for the synthesis of [3.2.1] and [3.3.1] bicyclic framework, the motifs found in many natural products. A convenient method described for the dehydration of ketoesters to generate conjugated and deconjugated alkynyl esters and conjugated allenyl esters. This sequential one-pot method...
Show moreWe report here the development of new and more general synthetic pathways for the preparation of allenyl and alkynyl carbonyls. These highly dense functionalized compounds were utilized as key intermediates for the synthesis of [3.2.1] and [3.3.1] bicyclic framework, the motifs found in many natural products. A convenient method described for the dehydration of ketoesters to generate conjugated and deconjugated alkynyl esters and conjugated allenyl esters. This sequential one-pot method involves the formation of a vinyl triflate monoanion intermediate that leads to the selective formation of alkynes or allenes depending on additives and conditions used. Product outcomes appear to be a function of unique monoand dianion mechanisms which are described. Our design of a Morita-Baylis-Hilman (MBH) reaction to include a fast silyl 1,3- Brook rearrangement has enabled the first ever anion-catalysis. This new reaction makes possible the addition of both aliphatic and aromatic aldehydes to s ilylallenes leading to carbinol allenoates. These new MBH reactions products allow for a fasttracked synthesis of [3.2.1] bisoxa-bicycles which make up the framework of many biologically active natural products including Vitisinol D. The development of cyclic addition of hydrazine nitrogen to unactivated alkynes catalyzed by non-metals is reported. Starting from readily accessible silyl allenyl esters, alkynyl hydrazines are prepared in one step and subsequently undergo unprecedented cyclization reactions in the presence of ammonium and phosphonium catalysts leading to dehydro-azaproline products. These heterocycles were also produced in high enantiomeric excesses using chiral ammonium phase transfer catalysts via a kinetic resolution pathway., The racemic synthesis of fully functionalized bicyclic core of Vitisinol D was achieved using allenyl ester as a key intermediate. The required electron withdrawing group (EWG) at the position was screened for better addition followed by the compatibility towards successive transformation and, finally, the ease of removal. A reductive aldol method to transform lactone-enol to the desired [3.2.1] bicycle was extensively studied to understand the stereoelectronic requirements for the formation of such bicyclic structures. Due to the necessity of selective protection and deprotection of many phenolic and aliphatic hydroxyls as well as ester groups, orthogonal protecting groups were established accordingly.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3332717
- Subject Headings
- Organic compounds, Synthesis, Carbonyl compounds, Synthesis, Cardiovascular system, Diseases, Treatment
- Format
- Document (PDF)
- Title
- Light intensity influences on algal pigments, proteins and carbohydrates: implications for pigment-based chemotaxonomy.
- Creator
- Grant, Cidya S., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
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Phytoplankton Chlorophyll a (CHLa), total protein, colloidal carbohydrates, storage carbohydrates and taxonomic pigment relationships were studied in two cyanophytes (Microcystis aeruginosa and Synnechococcus elongatus), two chlorophytes (Dunaliella tertiolecta and Scenedesmus quadricauda), one cryptophyte (Rhodomonas salina), two diatoms (Cyclotella meneghiniana and Thalassiosira weissflogii) and one dinophyte (Amphidinium carterae) to assess if algal biomass could be expressed in other...
Show morePhytoplankton Chlorophyll a (CHLa), total protein, colloidal carbohydrates, storage carbohydrates and taxonomic pigment relationships were studied in two cyanophytes (Microcystis aeruginosa and Synnechococcus elongatus), two chlorophytes (Dunaliella tertiolecta and Scenedesmus quadricauda), one cryptophyte (Rhodomonas salina), two diatoms (Cyclotella meneghiniana and Thalassiosira weissflogii) and one dinophyte (Amphidinium carterae) to assess if algal biomass could be expressed in other indices than just chlorophyll a alone. Protein and carbohydrates are more useful currencies for expressing algal biomass, with respect to energy flow amongst trophic levels. These phytoplankton were grown at low light (LL = 37 (So(Bmol photons m-2 s-1), medium light (ML = 70-75 (So(Bmol photons m-2 s-1), and high light (HL= 200 (So(Bmol photons m-2 s-1)., Even though pigment per cell increased with increasing light intensity, statistically light had very little effect on the CHL a : taxonomic marker pigment ratios, as they covaried in the same way. Protein, colloidal carbohydrates and storage carbohydrates per cell all increased with increasing light intensity, but they did not covary with CHLa. Statistical data showed that light intensity had a more noticeable effect on protein: CHL a, colloidal carbohydrate: CHLa, storage CHO: CHLa, therefore a general mathematical expression for these relationships cannot be generated. This study showed that light intensity does have an influence on these biomass indices, therefore, seasonal and latitudinal formulas may be required for meaningful algal biomass estimation. However, more studies are needed if that goal is to be realized., While studying the effects of light intensity on algal pigment content and concentration, a new pigment was isolated from a cyanophyte (Scytonema hofmanii) growing between 300-1800 (So(Bmol photons¨m-2¨s-1 and from samples collected in areas of the Florida Everglades. This pigment was characterized and structurally determined to possess indolic and phenolic subunits that are characteristic of scytonemin and its derivatives. In addition, the pigment has a ketamine functionality which gives it its unique polarity and spectral properties. Based on the ultra violet/visible absorbance data, this pigment was postulated to be protecting the chlorophyll a and cytochrome Soret bands as well as a and (Sb (Bbands of the cytochromes (e.g. cytc-562) in the photosynthetic unit.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3332257
- Subject Headings
- Plant pigments, Analysis, Photosynthetic pgiments, Analysis, Plant allometry, Enviornmental geochemistry, Marine algae, Analysis
- Format
- Document (PDF)
- Title
- Purification and characterization of two members of the protein tyrosine phosphatase family: dual specificity phosphatase PVP and low molecular weight phosphatase WZB.
- Creator
- Livingston, Paula A., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
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Two protein tyrosine phosphatases, dual specificity phosphatase PVP and low molecular weight phosphatase WZB were purified and characterized. PVP was expressed as inclusion bodies and a suitable purification and refolding method was devised. Enzyme kinetics revealed that p-nitrophenylphosphate and (Sb(B-naphthyl phosphate were substrates with KM of 4.0mM and 8.1mM respectively. PVP showed no reactivity towards phosphoserine. Kinetic characterization of WZB showed that only...
Show moreTwo protein tyrosine phosphatases, dual specificity phosphatase PVP and low molecular weight phosphatase WZB were purified and characterized. PVP was expressed as inclusion bodies and a suitable purification and refolding method was devised. Enzyme kinetics revealed that p-nitrophenylphosphate and (Sb(B-naphthyl phosphate were substrates with KM of 4.0mM and 8.1mM respectively. PVP showed no reactivity towards phosphoserine. Kinetic characterization of WZB showed that only pnitrophenylphosphate was a substrate with no affinity for Ç-naphthyl phosphate and phosphoserine. Optimal conditions for activity with PNPP were found at a pH of 5 with a KM of 1.1mM, kcat of 35.4s-1 and kcat/KM of 32.2s-1mM-1. Inhibition studies showed that phosphate, fluoride, and molybdate were competitive inhibitors with Ki of 3.2mM, 71.7mM, and 50.4(So(BM respectively and hydrogen peroxide abolished activity. Active site mutants of WZB Cys9Ser and Asp115Asn showed no activity.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/332911
- Subject Headings
- Protein-tyrosine phosphatase, Cellular signal transduction, Cell cycle, Regulation, Membrane proteins, Structure-activity relationships, Protein kinases
- Format
- Document (PDF)
- Title
- Development and applications of nucleophile assisting leaving groups (NALGs) with Titanium (IV) and Grignard reagents.
- Creator
- Li, Songye., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
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We report here the development of very efficient aryl- and quinolinyl- sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), which substantially accelerate the rate of nucleophilic substitution reactions with metal halides. Detailed synthesis and kinetics study are described herein. Our synthesized NALGs have shown great reactivity towards poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. The abundant...
Show moreWe report here the development of very efficient aryl- and quinolinyl- sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), which substantially accelerate the rate of nucleophilic substitution reactions with metal halides. Detailed synthesis and kinetics study are described herein. Our synthesized NALGs have shown great reactivity towards poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. The abundant existence of halide, azide and amine in natural products demands new synthetic pathway. To fulfill this requirement, new mild stereoretentive halogenations (chlorination, bromination and iodination) reactions have also been developed for secondary cyclic alcohols using NALGs involving titanium (IV) reagents. The novel methodology can be extended to Azidation reactions as well with titanium (IV) azide, in which Ti (N3)4 is the first time being engaged in organic synthesis. Beased on the NALGs theory we discover the chlorosulfite can be a simplest NALG and applied as the intermediate in mild one-pot stereoretentive halogenations (chlorination and bromination) using titanium (IV) halides as catalysts or stoichiometric reagents. These reactions were found to be particularly efficient for cyclic alcohols. Finally, an efficient mild bromination and iodination reaction for primary and secondary alcohols with Grignard reagents is also reported. This reaction exhibits the generality with substrates with various leaving groups. The important features of this reaction are that, for the first time, bromide formation using Grignard reagents without the Cu (I) catalysts.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3183130
- Subject Headings
- Chemical kinetics, Chemical reaction, Condition and laws of, Organic compounds, Synthesis, Organotransition metal compounds, Intermediates (Chemistry), Organic reaction mechanisms
- Format
- Document (PDF)
- Title
- Development of Nucleophile Assisting Leaving Groups (NALGs) and new stereoselective reactions using titanium(IV) reagents.
- Creator
- Mondal, Deboprosad., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
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We report here the development of very efficient sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), to accelerate the rate of nucleophilic substitution reactions involving poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. Indeed NALGs have shown exceptional ability in improving rate of nucleophilic substitution reactions. New very mild stereoretentive halogenations and azidation reactions have also been...
Show moreWe report here the development of very efficient sulfonate based leaving groups, termed Nucleophile Assisting Leaving Groups (NALGs), to accelerate the rate of nucleophilic substitution reactions involving poor nucleophiles and/or substrates traditionally considered too hindered to undergo nucleophilic attack. Indeed NALGs have shown exceptional ability in improving rate of nucleophilic substitution reactions. New very mild stereoretentive halogenations and azidation reactions have also been developed for secondary cyclic alcohols using NALGs involving titanium(IV) reagents. This reaction is particularly significant since the carbon-halogen bond is found widely in natural products and is used extensively as a synthesis intermediate. Azide is also a synthetically important functional group from which a variety of biologically important functional groups are conveniently obtained. Though stereoretentive chlorination and bromination reactions are known, we have developed, for the first time, a stereoretentive azidation reaction using titanium(IV) azide, a reagent not previously used in organic synthesis. During our development of stereoretentive reactions, we eventually developed very efficient, mild, two-step one-pot stereoretentive halogenations (chlorination and bromination) using titanium(IV) halides as catalysts or stoichiometric reagents. These reactions were found to be particularly efficient for cyclic alcohols. An efficient one pot stereoretentive amidation reaction for secondary cyclic alcohols is also reported. The important features of this reaction are that, for the first time, chlorosulfite (prepared in situ from alcohol using thionylchloride) has been used as a leaving group and titanium(IV) fluoride as an activator., Utilization of those two reagents is unique as thionylchloride has never been used for nucleophilic substitution reactions except in chlorination procedures. In addition, this work has found new and creative applications for titanium (IV) fluoride, a reactant rarely used in organic synthesis. Further exploiting the unique reactivity of titanium(IV), reactions of alkenes with various nucleophiles have been developed with this reagent in both catalytic and stoichiometric quantities. It was observed that a-substituted aromatic conjugated alkenes dimerize to generate important indan class of compounds which are very important in the polymer industry. In addition, non conjugated unactivated alkenes react with various nucleophiles to yield the adduct.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/3159264
- Subject Headings
- Chemical reaction, Condition and laws of, Organic compounds, Synthesis, Chemical templates, Intermediates (Chemistry), Organotransition metal compounds, Organic reaction mechanisms
- Format
- Document (PDF)