Browsing by Subject "Prodrug"

Now showing 1 - 4 of 4
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    Development of chemical probes for intracellular nucleotide delivery, profiling of the metabolic fate(s) of nucleoside monoester phosphoramidates, and a nucleotide mimetic inhibitor of eIF4E
    (2018-07) Okon, Aniekan
    Significant progress has been made towards the development of phosphate prodrugs for intracellular delivery of monophosphates. Such efforts led to the successful application of the aryloxy amino acid phosphoramidate (ProTide) strategy for development of sofosbuvir. Although widely successful, several drawbacks of the ProTide strategy limit its utility for delivery of significant levels of nucleotide analogs in tissues other than the liver. In order to broaden the utility of phosphate prodrugs, we have developed pronucleotide strategies that address the inefficiencies of the ProTide system. Chapter 2 describes the design and development of an anchimerically activated pronucleotide strategy, incorporating 2-(methylthio)ethyl and tryptamine as phosphate protecting moieties. The prodrug is activated by a sulfur mediated intramolecular cyclo-de-esterification reaction to yield a monoester phosphoramidate, which gets hydrolyzed by HINT1 to release a monophosphate. In a proof-of-concept application, we applied the pronucleotide strategy towards intracellular delivery of 7-Chlorophenoxyethyl guanosine monophosphate, as a chemical tool for translational control of protein synthesis. Furthermore, in Chapter 3 we provide another proof-of-concept application of the new pronucleotide strategy for intracellular delivery of 2´-C-β-Methyl guanosine monophosphate as an anti-Dengue virus (DENV) agent. In a related project, we sought to profile the protein interacting partners of nucleoside monoester phosphoramidates. Mapping the small molecule-protein interactome of nucleoside monoester phosphoramidates should help us decipher the mode of cellular uptake and identify other metabolizing enzymes of nucleoside monoester phosphoramidates (excluding HINT1). Chapter 4 outlines the design and synthesis of phosphoramidate-based photoaffinity probes as chemical tools for profiling the protein binding partners of nucleoside monoester phosphoramidates. The synthesized probes were utilized for in vitro proteomics studies in whole cell extracts (lysates) and in live cells. Finally, we describe the design and development of a nucleotide mimetic inhibitor of eIF4E in Chapter 5. As a proof-of-concept application, we employed a sulfamido alkyl moiety as a substitute for 5´-phosphate in the design of 5´-mRNA cap analog antagonists of eIF4E. We successfully synthesized a mimetic of 7-Chlorophenoxyethyl guanosine monophosphate and demonstrated that its binding potency to eIF4E is comparable to that of the parent nucleotide, with only a modest loss in binding potency.
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    Evaluation of Eukaryotic Initiation Factor 4E (eIF4E) antagonist 4Ei-1 in mammalian breast cancer and lung cancer cells : chemosensitizaiton with low cytotoxicity.
    (2012-08) Li, Shui
    The development of cancer and fibrotic diseases has been shown to be highly dependent on disregulation of cap-dependent translation. Binding protein eIF4E to N7-methylated guanosine capped mRNA has been found to be the rate-limiting step governing translation initiation; and therefore represents an attractive target for drug discovery. Our group has found that 7-benzyl guanosine monophosphate (7Bn-GMP) is a potent antagonist of eIF4E cap binding (Kd = 0.8 uM). Recent X-ray crystallographic studies have revealed that the cap-dependent pocket undergoes a unique structural change in order to accommodate the benzyl group. Unfortunately, 7Bn-GMP is not cell permeable. Recently, we have prepared a tryptamine phosphoramidate prodrug of 7Bn-GMP, 4ei1, and shown that it is a substrate for human histidine triad nucleotide binding protein (hHINT1) and is inhibit eIF4E initiated epithelial-mesenchymal transition (EMT) by Zebra fish embryo cells. To assess the intracellular uptake of 4ei1 and conversion to 7Bn-GMP by cancer cells, we developed a sensitive assay using LC-ESI-MS/MS for the intracellular quantitation of 4ei1 and 7Bn-GMP. When incubated with the breast cancer cell line MDA-231; or lung cancer cell lines H460, H383 and H2009, 4ei1 was found to be rapidly internalized and converted to 7Bn-GMP. Since oncogenic mRNAs are predicted to have the highest eIF4E requirement for translation, we carried out chemosensitization studies with 4ei1. The prodrug was found to chemosensitize both breast and lung cancer cells to non-toxic levels of gemcitabine. Further mechanistic studies revealed that the expressed levels of eIF4E were substantially reduced in cells treated with 4ei1 in a dose dependent manner. The levels of eI4E could be restored by treatment with the proteasome inhibitor MG-132. Taken together, our results demonstrate that 4ei1 is likely to inhibit translation initiation by eIF4E cap binding by both antagonizing eIF4E cap binding and initiating eIF4E proteasomal degradation.
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    Method Development and Degradation Studies to Verify the Stabilization of a Gallium Prodrug of Epinephrine
    (2021-09) Livezey, Nicholas
    Utilizing the unique and varied properties of metals, such as their redox activity, lability, and net charge, metal-based prodrugs can be designed and optimized for numerous applications. The most prominent usage of metal-based prodrugs has historically been anti-cancer agents, though there have been more recent efforts in the development of theranostic and antimicrobial agents as well. Gallium has promise for extending the scope of metal-based prodrugs, as it has been FDA approved for the treatment of tumors and hypercalcemia. Epinephrine is a compelling target for a gallium-based prodrug as conventional prodrugs are not suitable for the treatment of anaphylactic shock. This is because the prodrugs are inactive during their long half-lives. Additionally, as should mitigate drug degradation from high pH, light, and heat. The development of a novel gallium prodrug of epinephrine establishes the first prodrug treatment of anaphylactic shock, and extends the chemical space of metal-based prodrugs.
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    Synthesis and characterization of silicate ester prodrugs and poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) block copolymers for formulation into prodrug-loaded nanoparticles
    (2012-09) Wohl, Adam Richard
    Fine control of the physical and chemical properties of customized materials is a field that is rapidly advancing. This is especially critical in pursuits to develop and optimize novel nanoparticle drug delivery. Specifically, I aim to apply chemistry concepts to test the hypothesis "Silicate ester prodrugs of paclitaxel, customized to have the proper hydrophobicity and hydrolytic lability, can be formulated with well-defined, biocompatible, amphiphilic block copolymers into nanoparticles that are effective drugs." Chapter 1 briefly describes the context and motivation of the scientific pursuits described in this thesis. In Chapter 2, a family of model silicate esters is synthesized, the hydrolysis rate of each compound is benchmarked, and trends are established based upon the steric bulk and leaving group ability of the silicate substituents. These trends are then applied to the synthesis of labile silicate ester prodrugs in Chapter 3. The bulk of this chapter focuses on the synthesis, hydrolysis, and cytotoxicity of prodrugs based on paclitaxel, a widely used chemotherapeutic agent. In Chapter 4, a new methodology for the synthesis of narrowly dispersed, "random" poly(lactic-co-glycolic acid) polymers by a constant infusion of the glycolide monomer is detailed. Using poly(ethylene glycol) as a macroinitiator, amphiphilic block copolymers were synthesized. Co-formulating a paclitaxel silicate and an amphiphilic block copolymer via flash nanoprecipitation led to highly prodrug-loaded, kinetically trapped nanoparticles. Studies to determine the structure, morphology, behavior, and efficacy of these nanoparticles are described in Chapter 5. Efforts to develop a general strategy for the selective end-functionalization of the polyether block of these amphiphilic block copolymers are discussed in Chapter 6. Examples of this strategy include functionalization of the polyether with an azide or a maleimide. Finally, Chapter 7 provides an outlook for future development of the strategies described in this thesis and summarizes the results and conclusions of the experimental results that led to the development of the therapeutic, paclitaxel silicate-loaded, polymeric nanoparticles.