Amines are ubiquitous in nature and serve a variety of functions in living organisms. Because of this fact amines are of great biological and pharmaceutical interest. The iridium catalyst (pentamethylcyclopentadienyl) iridium dichloride dimer ([Cp*IrCl2]2) has been used in a number of ways to synthesize new carbon-nitrogen bonds. These studies were directed toward the development of a method for the iridium catalyzed N-alkylation of alpha-amino acid esters as well as the development of a strategy for synthesis of the natural product 275A. We have optimized a method for the N-alkylation for alpha-amino acid esters. Using this method, we have N-alkylated a series of alpha-amino acid esters with a variety of alcohols. We have shown that the N-alkylation of the alpha-amino acid esters works consistently and gives the desired products in moderate to high yields. We have examined the effect of this method on the chiral center of the obtained products by analyzing their optical rotation. Evaluation of these specific rotations indicated racemization was occurring but it is believed that any loss of the chiral center is due to the reaction conditions. Amphibian alkaloids are of great interest to the pharmaceutical and academic communities due to their biological activities. Unfortunately, they are not naturally available in large quantities which makes total synthesis the most common method of generating these compounds for evaluation. One amphibian alkaloid class of interest to us are the Lehmizidines. These are bicyclic ring structures consisting of a 7-member and 5-member ring with a nitrogen bridgehead. The alkaloid, 275A, was selected as a target for a general synthetic approach. This synthetic approach required the synthesis of novel diols. The construction of these diols along with a method for the synthesis of the azepane ring is presented here.

Intermittent fevers caused by Plasmodium parasites have been known for millennia, and have caused untold human suffering. Today, millions of people are afflicted by malaria each year, and hundreds of thousands die. Historically, the most successful synthetic antimalarial drug was chloroquine, as it was safe, inexpensive, and highly efficacious. However, plasmodial resistance to chloroquine now greatly limits its utility. Previously in our laboratories it has been shown that attachment of a "reversal agent moiety" to the side chain of chloroquine can result in the restoration of activity against chloroquine-resistant strains of P. falciparum malaria. In the first part of the work presented here, a study has been made of the importance of the quinoline ring substitution pattern to the activity of such reversed chloroquines. The compounds presented here include those bearing a substituent in the 2-, 5, 6-, 7-, and/or 8- position, and include those with chloro, bromo, iodo, fluoro, nitro, trifluoromethyl, methyl, and methoxy substituents. For reversed chloroquines, 2-, 5-, and 8- substituents have been found to decrease in vitro antiplasmodial activity against P. falciparum relative to 7-chloro substitution, whereas 6- and 7- substituted compounds with various substituents have in many cases similar activity to that of 7-chloro substituted compounds. Little difference has been observed between 6- and 7- substitution, or between chlorine and a methyl group in position 6. In most cases these effects on activity are directionally similar to those observed for chloroquine analogs without an attached reversal agent, but the magnitude of the effect is generally smaller, suggesting that the activities of reversed chloroquines are less affected by modifications to the quinoline ring system than is true for chloroquine analogs without an attached reversal agent. The second portion of this work presents an asymmetrical bis-quinoline (PL241) that is highly active against P. falciparum malaria, with an IC50 of less than 0.1 nM for all strains tested. Mechanistic studies have been performed in which the substitution patterns of the two quinoline rings of PL241 are modified in ways that indicate that either ring system is equally capable of participating in the antimalarial activity of these compounds. The excellent in vitro antiplasmodial activity of PL241 makes this a compound of great interest for further development as a potential antimalarial drug. In the third part of this work, a survey has been made of antimalarial treatments recommended in the European medical literature from the time of Pliny the Elder (active in the first century A.D.) through the advent of modern malaria chemotherapy in the early twentieth century. In the fifteen primary sources utilized in this study, 251 distinct substances - primarily plants - were identified as having likely been used in the treatment of malaria. Of the 38 substances that were described in three or more sources, at least fifteen have been examined by other workers for antiplasmodial activity; in many cases, they were found to have antiplasmodial activity in vitro or in vivo. However, the majority of the phytotherapies for malaria identified in this project have not yet been tested against Plasmodium species, and may provide valuable leads in the search for new compounds active against drug-resistant malaria.

Prodigiosins and tambjamines are natural compounds from bacterial and marine sources belonging to a family containing a common 4-methoxy-2,2'-bipyrrole core. These compounds have received a lot of interest due to their promising biological activities. Studies have suggested DNA as a potential therapeutic target for the natural prodigiosin and tambjamine due to their ability to facilitate oxidative DNA cleavage in the presence of Cu2+. Based on this we sought to study the metal binding activity of new prodigiosin and tambjamine analogues. A new prodigiosin analogue was synthesized and complexed with Cu2+. This revealed 1:1 complex formation between the tripyrrole and Cu2+ that was confirmed by mass spectra and NMR spectra analysis. In addition in situ studies also revealed that our new analogues of prodigiosin cannot bind Zn2+ when the methoxy group on ring B is replaced by an alkyl group or when one of the ring nitrogens is methylated. Our UV-Vis experiments with calf thymus DNA showed that prodigiosins and tambjamines bind DNA mainly through an external mode, suggesting that hydrogen bonding between the pyrrole ring nitrogens and the bases of DNA takes precedence over stacking interactions. For the new Cu2+ complex synthesized however, we observed spectral changes that suggest intercalation into DNA. DNA cleavage experiments revealed that the prodigiosin-Cu complex is able to convert supercoiled DNA into its linear form. The data from the gel shift assays fit well to a first-order consecutive reaction model. In addition to preformed metal complexes, we showed DNA cleavage by in situ complexation of the ligands in the presence of Cu2+. However, although we showed Zn2+ complex formation with prodigiosin analogues, in situ studies did not show induction of DNA cleavage by Zn2+ complexes under our experimental conditions.

In vitro protein selection has had major impacts in the field of protein engineering. Traditional screens assay individual proteins for specific function. Selection, however, analyzes a pool of mutants and yields the best variants. Phage display, a successful selection technique, also provides a reliable link between variant phenotype and genotype. It can also be coupled with high throughput sequencing to map protein mutations; potentially highlighting vital mutations in variants. We propose to apply this technique to cancer therapy. RAF, a serine/threonine kinase, is critical for cell regulation in mammals. RAF can be activated by oncogenic RAS, found in over 30% of cancers, to drive cancer proliferation. Rigosertib, a benzyl styryl sulfone in phase III clinical trials for myelodysplastic syndrome (MDS), is an inhibitor of the RAS binding domain (RBD) in RAF. Phage display can be used to select RAF mutants for RAS binding affinity, in the presence of Rigosertib. High-throughput sequencing of these variants can provide a means of anticipating, and mapping resistance to this anti-cancer drug.

Sulfated low molecular weight lignins (LMWLs) have shown good activity as anticoagulants by allosterically inhibiting thrombin, as well as promising agents for treating emphysema through inhibition of elastolysis, oxidation, and inflammation. Sulfated LMWLs are chemo-enzymatically synthesized from starting monomers caffeic, ferulic, and sinapic acid into sulfated dehydropolymers known as CDS, FDS, and SDS. To further the LMWLs’ development as drugs, their structural composition and physicochemical characteristics were defined in this work. The molecular weight distribution profile of the sulfated LMWLs from size exclusion chromatography performed on a high pressure liquid chromatography system (SEC-HPLC) changed from bimodal when no surfactant is used in the mobile phase of the HPLC to unimodal when surfactant is used in the mobile phase. This indicates that some large molecular weight species, likely an aggregate of smaller molecular weight chains, are disrupted when surfactant is present. The resulting estimates of molecular weight calculated when surfactant is used in the mobile phase resulted in peak average molecular weights of 5700 Da for CDS, 7400 Da for FDS, and 4300 Da for SDS. These molecular weights are 17-45% higher and can be considered more accurate than the previously reported molecular weights (CDS: 3320 Da, FDS: 4120 Da, SDS: 3550 Da) because they were measured directly whereas previous estimates were calculated from GPC-HPLC data of the unsulfated LMWL precursors. Elemental analysis and distribution coefficient measurements were also performed on the LMWL library, revealing information about the level of sulfation and hydrophobic character of the sulfated LMWLs.

A series of rigid azetidenyl-based methamphetamine analogs were synthesized from commercially available N-Boc-azetidinone. The benzylideneazetidine analogs were prepared via a Wittig olefination via the ylides generated from the corresponding triphenylphosphonium benzylhalide salts. The substituted benzylazetidine analogs were synthesized from the corresponding benzylideneazetidienes via hydrogention over palladium and platinum catalysts. The benzylideneazetidine and benzyliazetidine analogs were evaluated at monoamine transporters as a part of preliminary structure-activity study for the development of novel monoamine transporter ligands. The binding affinities of the azetidine analogs were determined at dopamine (DAT) and serotonin (SERT) transporters in rat brain tissue preparations. The preliminary in vitro binding studies revealed that the rigid scaffold of the azetidine ring system was an effective substitution for the 2-aminopropyl group of methamphetamine and led to compounds with nanomolar binding affinity at dopamine and serotonin. In general, the benzylideneazetidine analogs were more potent than the corresponding benzylazetidine analogs. In addition, the azetidine analogs were more selective for the serotonin transporter than the dopamine transporter. The 3-(3,4-dichlorobenzylidene)azetidine (24m) was the most potent analog of the series with Ki values of 139 nM for SERT and 531 nM for DAT (DAT/SERT = 3.8).

Cannabis and its derivatives have been used for both medicinal and recreational purposes. The study of this plant led to the discovery of over 60 cannabinoids, found exclusively in cannabis, that contribute to the behavioral effects of cannabis use, the most common is delta-9-tetrahydrocannabinol. Cannabinoid receptors function to increase activity in the mesolimbic dopamine reward system. Dopamine is a neurotransmitter that plays a major role in addition and its regulation plays a crucial role in mental and physical well-being. There is evidence that CB1 receptors are important to the reinforcing effects and the development of physical dependence on opiate drugs. Studies have shown that increased levels of dopamine are consistent with addiction while reduced levels lead to a decline in recreational use. The goal of this research is to design, synthesize and develop potential CB1 receptors that exhibit a neutral cannabinoid antagonist pharmacological profile.

Invasive fungal infections are a major threat to immune-compromised patients. There is a critical need to develop new antifungal agents because of increasing resistance to the common antifungal drugs. In the first part of this dissertation, methods for preparation of novel barbiturate saponin as antifungals and their biological activities would be described. Barbiturates and steroidal saponins have shown remarkable antifungal activity in the biological assays. Therefore, attempts were directed to combine the barbiturate with the steroid to give novel antifungal agents. The need for extensive SAR studies and to better understand these compounds efforts were directed to synthesize novel saponin barbiturates. Glycosylation of barbiturates was achieved under basic conditions to synthesize mono and disaccharide barbiturates. Saccharide molecules were directly introduced into the barbiturate without requiring protection and deprotection of saccharides. Efficient methods were developed for synthesis of 3β derivatized steroid derivatives containing ether, carbonate, ester and carbamate linker. Synthesized mono and disaccharide barbiturates were incorporated into the steroidal skeleton to give the novel antifungal agents. Several reaction conditions were explored to give the best yield under the most efficient reaction conditions. However, a better understanding and extensive SAR study needs to be done in order to develop more promising and potent antifungal compounds. The second part of this dissertation describes the progress towards monocysteine metal complex synthesis and their biological activities. In this attempt, several protection deprotection strategies were explored and some novel protective groups were designed for peptide synthesis.

Telomeres are nucleoprotein complexes found at the ends of linear eukaryotic chromosomes. Telomeres consist of a short sequence of repetitive double stranded DNA, TTAGGG repeats in humans (and all mammals), and a complex of 6 proteins, termed the shelterin complex. The length of the telomeres varies greatly between species, from approximately 300 base pairs in yeast to many 10-15 kilo bases in humans, because of the end replication problem this length get shorten with each cell division and ultimately leads to cell death. However the immortal eukaryotic cells and some transformed human cells over come this incomplete end replication problem with the use of enzyme called Telomerase. Telomerase is a ribonucleoprotein enzyme that adds a specific DNA sequence repeats (TTAGGG) to the 3¢ end of DNA strands in the telomere regions. However from the telomerase activity studies, it was concluded that telomerase is active in almost 90% of human cancers but not in normal somatic tissues. Finally, the low or transient expression of telomerase in normal tissues, including normal stem cells, and the generally longer telomeres in normal cells versus tumor cells provide a degree of tumor specificity to telomerase-based drugs and reduce the probability of toxicity to normal tissue. All of these factors suggest that cancer drugs based on telomerase might have a broad therapeutic window. This dissertation focusing on the synthesis of acridine derivatives that have the capability to inhibit the enzyme telomerase. Several N-acridyl maleimide (NAM), N-acridyl succinimide (NAS) and N-acridyl phthalimide (NAP) derivatives have been synthesized and evaluated for their anti cancer activity against various cancer cell lines. While synthesizing acridine derivatives it was required to form the C-N bonds at various stages. Developed a copper-nicotinic acid complex, which catalyzes the coupling of aryl halides with N-formyl amines and cyclic imides to form C-N bond. Explored Cu (II) catalyzed formation of C-N bond by coupling aryl halides with various N-nucleophiles such as formamide, N,N-dimethyl formamide, N-formyl amines and various cyclic imides.

The focus of these studies was directed towards the synthesis of novel N-heterocyclic compounds and pharmacological evaluation of these compounds for activity at monoamine transporters. A series of novel piperidine and pyrrolidine analogues were prepared from commercially available starting material with a three and four step synthetic method, respectively. A variety of substituents on the aromatic ring were incorporated to achieve a diverse library of compounds. The preliminary binding studies of piperidine molecules showed strong affinity towards serotonin transporters and moderate affinity towards dopamine transporters. The focus of further studies was directed towards utilization of iridium catalysis for the development of new synthetic methods for biologically important molecules. This research has led to the development of a new synthetic strategy for the construction of nicotine and its analogues. In addition, the iridium catalysis was also used for alkylation of amides with primary and secondary alcohols under microwave conditions.