ABSTRACT Manipulation of biological targets using synthetic or naturally occurring organic compounds has been the focal point of medicinal chemistry. The work described herein centers on the synthesis of organic small molecules that are targeted either to cell surface receptors, to the ribosomal catalytic center or to human immunodeficiency virus reverse transcriptase. Bleomycins (BLMs) are a family of naturally occurring glycopeptidic antitumor agents with an inherent selectivity towards cancer cells. DeglycoBLM, which lacks the sugar moiety of bleomycin, has much lower cytotoxicity in cellular assays. A recent study using microbbuble conjugates of BLM and deglycoBLM showed that BLM was able to selectively bind to breast cancer cells, whereas the deglyco analogue was unable to target either the cancer or normal cells. This prompted us to further investigate the role of the carbohydrate moiety in bleomycin. Fluorescent conjugates of BLM, deglycoBLM and the BLM carbohydrate were studied for their ability to target cancer cells. Work presented here describes the synthesis of the fluorescent carbohydrate conjugate. Cell culture assays showed that the sugar moiety was able to selectively target various cancer cells. A second conjugate was prepared to study the importance of the C-3 carbamoyl group present on the mannose residue of the carbohydrate. Three additional fluorescent probes were prepared to improve the uptake of this carbohydrate moiety into cancer cells. Encouraged by the results from the fluorescence experiments, the sugar moiety was conjugated to a cytotoxic molecule to selectively deliver this drug into cancer cells. The nonsense codon suppression technique has enabled researchers to site specifically incorporate noncanonical amino acids into proteins. The amino acids successfully incorporated this way are mostly α-L-amino acids. The non-α-L-amino acids are not utilized as substrates by ribosome catalytic center. Hoping that mutations near the ribosome peptidyltransferase site might alleviate its bias towards α-L-amino acids, a library of modified ribosomes was generated. Analogues of the naturally occurring antibiotic puromycin were used to select promising candidates that would allow incorporation of non-α-L-amino acids into proteins. Syntheses of three different puromycin analogues are described here. The reverse transcriptase enzyme from HIV-1 (HIV-1 RT) has been a popular target of HIV therapeutic agents due to its crucial role in viral replication. The 4-chlorophenyl hydrazone of mesoxalic acid (CPHM) was identified in a screen designed to find inhibitors of strand transfer reactions catalyzed by HIV-1 RT. Our collaborators designed several analogues of CPHM with different substituents on the aromatic ring using molecular docking simulations. Work presented here describes the synthesis of eight different analogues of CPHM.

Changes to a cell's DNA can result in cancer, which is permanently sustained cellular proliferation. When malfunctioning genes, oncogenes, were verified to be of human origin in the 1970s, drugs were designed to target their encoded, abnormal enzymes. Tyrosine kinases have been established as an oft-modified oncogene enzyme family, but the protein tyrosine phosphatases (PTPs) were not investigated as thoroughly. PTPs have gradually been established as relevant enzymes that work in tandem with tyrosine kinases in cell signaling and are not just "house-keeping" enzymes. Some PTPs are thought to initiate tumorigenesis, and others may play a complementary role after the onset of cancer by extending the duration of cellular signals. Reversible inhibition of these enzymes by an oxalylamino group substituted on an ortho-carboxy aryl have been described in the literature. Modification of the oxalylamino group to favor irreversible inhibition of these cysteine-dependent enzymes may prevent inhibitor efflux by cells and subsequent mutation to gain resistance. Replacement of the oxalylamino group with halogenated propanoate and propenoate esters minimally inhibited cancer cell growth but did not inhibit activity of PTPs. Of the ortho-carboxy aryl structures, a methyl dichloropropanoate (compound 24) and a lactone alkene (compound 29) inhibited cell growth by 50% (GI-50) at micromolar concentrations. The GI-50s for compounds 24 and 29 were 19.9 (DU-145, prostate carcinoma) and 9.4 micromolar (A549, lung cancer), respectively. In contrast, brominated nitro lactones were able to inhibit both cancer cell growth and the activity of PTPs. In a sulforhodamine B assay, these compounds were able to achieve GI-50s as low 5.3 micromolar (compound 33 against BXPC-3, pancreatic adenocarcinoma), and some killed 50% of cancer cells (LC-50) at micromolar concentrations. Compound 33 displayed LC-50 of 23.3 micromolar (BXPC-3), and compound 35 had LC-50s of 32.9 and 32.7 micromolar against BXPC-3 and colon adenocarcinoma (KM20L2), respectively. A single concentration (100 micromolar) inhibition assay of inhibitor PTPs resulted in no enzyme activity for 4 out of 5 PTPs tested with compound 33. Similar results were obtained for compounds 35 and 37. Future analysis will determine if these bromo nitro lactones are irreversibly inhibiting PTPs.