Chemokine receptor CCR5 (CCR5) is a G-protein coupled receptor (GPCR) predominantly expressed on leukocytes, or white blood cells.1–3 During inflammation, the body releases chemokines that bind to receptors such as CCR5 and attract leukocytes to the area of inflammation, leading to an immunological response.1 CCR5 is also an important receptor in the human immunodeficiency virus's (HIV-1) invasion of host cells, as CCR5 acts as a co-receptor that facilitates HIV-1 viral entry.4,5 The continued destruction of leukocytes as a result of HIV-1 viral entry produces a disease state called acquired immunodeficiency syndrome (AIDS).5 Of note, this receptor is also expressed on the glial cells of the central nervous system (CNS).6,7 The mu-opioid receptor (MOR) is also a GPCR is predominantly expressed in the central nervous system.8–10 It binds to signal molecules such as endorphins and produces analgesic effects upon activation.9 The protein binds to morphine and morphine derivatives, which are extracts from the opium poppy plant.10 Besides the analgesic effects produced from MOR activation, morphine and its derivatives are also highly addictive and can result in drug dependence.11 Like CCR5, MOR is also expressed on the glial cells of the CNS.8 The accelerated progression of AIDS-like symptoms, in particular HIV-associated neurocognitive disorders (HANDS), has been observed in opiate-addicted patients.6,7,12–14 It has been discovered that opiate-addicted patients who have AIDS are susceptible to higher levels of HIV-1 viral proliferation and a greater level of CNS host cell destruction.12–14 This is because the activation of MOR by opiates appears to increase the expression of CCR5 on glial cells and may alter CCR5's conformational state to one more susceptible to HIV-1 binding.15 Then, entry and subsequent destruction of glial cells by HIV-1 leads to the release of neurotoxic HIV-1 proteins that destroy primary neuronal cells.15 A bivalent ligand targeting the putative CCR5-MOR heterodimer was proposed to probe the interaction between the two proteins and act as a potential therapeutic ligand to combat neuroAIDS.16 A bivalent ligand attaching maraviroc, a CCR5 antagonist, with naltrexone, a non-selective opioid receptor antagonist, was synthesized and tested in vitro.16 The initial bivalent ligand was separated by a 21-atom spacer (Figure 1), the length of which was dictated by modeling studies and other bivalent ligands.17 The spacer was attached to the 6-position of 6β-naltrexamine, a modified variation of naltrexone replacing the 6 position ketone with an amino group, and the 4'-position of the maraviroc phenyl ring.16 These positions were chosen based on separate modeling studies of naltrexone and maraviroc docked in homology models of MOR and CCR5, respectively.18,19 From these studies, it appeared as if these positions were optimal given that they faced outward from their respective binding pockets and hence could tolerate spacer attachment.18,19 However, based on these modeling studies there was also room for structure optimization of the bivalent molecule.17–19 The original 21-atom spacer was subjected to numerous structural changes by our laboratory in an effort to increase CCR5 and MOR binding. The first type of structural modification included changing maraviroc's point-of-attachment to the spacer from the 4'- to the 3'-position. Based on results from calcium mobilization functional assays involving CCR5-transfected human acute lymphoblastic leukemia (MOLT-4) cells, the activity of the bivalent molecule decreased from an IC50 of 126.0 ± 28.0 to 1340.0 ± 110.0 when the point-of-attachment was changed to the 3'-position. Thus, the 4'-position was kept in future structural studies. After this, additional structural modification was pursued in the form of changing spacer length. We synthesized two additional bivalent ligands, i.e., 19-atom and 23-atom bivalents with their controls. It is important to note that each of these molecules had a separate synthetic route starting with a specified diamine spacer. For the 19-atom bivalent molecule and its controls, the starting material was 1,5-diaminopentane. For the 23-atom bivalent molecule and its controls, the starting material was a 1,9-diaminononane molecule. Once these molecules were synthesized, in vitro biological testing was conducted. The bivalent molecules and 6β-naltrexamine controls were subjected to a competitive radioligand binding assay involving hMOR membranes and then to a calcium mobilization functional assay involving hMOR-transfected chinese hamster ovarian (CHO) cells (Figure 2). The affinities from the radioligand binding assay were similar in order-of-magnitude to other modified opioid antagonists and had a fold-decrease in affinity relative to naltrexone ranging from 1.1 to 9.3. The IC50 values from the calcium mobilization assay were similar in order-of-magnitude to other modified opioid antagonists and had a fold-decrease in activity relative to naltrexone ranging from 7.6 to 32. Thus, it was concluded that spacer attachment to the 6-position of 6β-naltrexamine was tolerated in MOR-binding. The bivalent molecules and maraviroc controls were then tested in calcium mobilization assays involving CCR5-transfed MOLT-4 cells to assess CCR5 activity. Unlike in the hMOR-CHO calcium mobilization assay, the activity of the bivalent molecules for CCR5 was not similar in magnitude to the receptor's antagonist, maraviroc. The 23-atom bivalent and 19-atom bivalent had fold-decreases in activity relative to maraviroc of 1,100 and 250, respectively. Recently, the co-crystal structure of maraviroc bound to CCR5 was published in Science.20 Contrary to our previous understanding, it appeared as if modifications to the phenyl ring in maraviroc were not tolerated.20 After the biological testing, conformational analysis on the 19-, 21- and 23-atom bivalent compounds using Confort conformational modeling software was conducted. This was done to observe the possible viable conformations of each molecule. It was hypothesized that 1) the molecules could adopt viable conformations for binding to two different receptors simultaneously and that 2) the molecules could adopt similar conformations relative to each other. The first hypothesis was proposed to assess the realism of the project's design strategy whereas the second was to analyze whether significant conformational differences could account for differences in binding activity between the three molecules. Results from this experiment showed that the molecules all adopted viable conformations for binding to two receptors simultaneously and that the conformational differences between the three molecules were negligible enough to conclude that significant differences in binding were not because of conformational differences. In conclusion, our laboratory synthesized a set of bivalent compounds to probe the CCR5-MOR heterodimer and tested such compounds in vitro. While spacer modifications to the 6-position of naltrexone were tolerated in hMOR competitive radioligand binding assays and in hMOR-CHO calcium mobilization assays, spacer modifications to maraviroc's 4'-position on the phenyl ring were not tolerated very well in CCR5-MOLT-4 calcium mobilization assays. Therefore, future design strategies might focus on changing the spacer's point-of-attachment to the maraviroc molecule.

The khat plant, catha edulis, has been abused for some time in the Middle East and the African horn for its short-term stimulant effects. However, it was not until 1975 when cathinone, β-ketoamphetamine, was identified as the major stimulant component of khat. Structural analogues of cathinone, synthetic cathinones, are new psychoactive substances available on the clandestine market of numerous countries including the USA. Abuse of these new illicit stimulants is a worldwide growing health concern which necessitates the investigation of the pharmacological properties of these new drugs of abuse. The abuse liabilities of these compounds seem to be related to the three major monoamine transporters (MATs): the dopamine, norepinephrine, and serotonin transporters (DAT, NET, and SERT, respectively). Synthetic cathinones act as either releasing agents by stimulating the release of the presynaptic neuronal content of neurotransmitters, or as reuptake inhibitors by inhibiting normal physiological reuptake of neurotransmitters from the synaptic cleft. Bupropion (DAT/NET reuptake inhibitor) is clinically prescribed for the treatment of depression and smoking cessation, whereas its closely related cousin, cathinone (DAT/NET releasing agent), is a drug of abuse. Deconstruction of bupropion (i.e., a stepwise conversion – or structural transition – of bupropion to cathinone) and investigation of the actions of the deconstructed analogues at the three major MATs showed that the steric bulk at the terminal amine controls the molecular mechanisms of these compounds at MATs (i.e. reuptake inhibition versus substrate-induced release). This study also concluded that bupropion is abused, because it is a cathinone derivative. Methcathinone (MCAT), N-methylcathinone, (DAT/NET releasing agent) is a recreational street drug and a US Schedule I substance; however, new MCAT analogues are continually appearing on the clandestine market to circumvent prosecution under the Controlled Substance Analog Enforcement Act. We investigated the actions and structure-activity relationships of a series of 3-substituted MCAT analogues at MATs and their quantitative structure-activity relationships to determine the physicochemical properties of the 3-position substituents important for the releasing actions of these compounds. This study indicated that the steric bulk of the 3-position substituents controls the selectivity of these compounds at MATs.

Atherosclerotic disease is an almost universal phenomenon and increases in severity and frequency with increasing age. Atherosclerosis may contribute to several disorders including bursting of an artery, blockage of an artery, or induction of arterial clotting. The culmination of these diseases is usually premature since at the time of death the unaffected organs are in reasonably satisfactory condition and could have operated for several more years. Among the many factors which act in concert to produce the disease, serum cholesterol levels play a central role. It has been suggested that the lowering of cholesterol levels will provide an effective means of treatment and prophylaxis of atherosclerosis. The purpose of this investigation was to rationally design, synthesize, and evaluate agents to lower serum cholesterol levels by the inhibition of cholesterol biosynthesis at the site of the reduction of β-hydroxy-β-methylglutaryl coenzyme A (HMG CoA) to mevalonic acid. This reaction, mediated by HMG CoA reductase, was chosen as the inhibition target because it is the first irreversible reaction, the rate limiting step for the pathway, and the site of physiological regulation of cholesterol biosynthesis. Rat liver HMG CoA reductase provided a convenient test system for these agents. Using the previously reported compound, 1-(4-biphenylyl)-n-pentyl hydrogen succinate as parent inhibitor, the present study accomplished two goals: first, a contribution toward elucidation of reversible binding sites for these inhibitors and second, probing of the suggested nonpolar n-pentyl binding area of the enzyme by introduction of a functional group capable of alkylating the enzyme and providing irreversible inhibition. The first objective was approached by replacing the ester of the parent inhibitor with an amide functional group. The resulting glutarimide exhibited inhibition comparable to that of the parent inhibitor. This may be taken as evidence that isosteric replacement of the parent ester group with the amide N-H did not seriously alter the ability of the inhibitor to bind to the enzyme and that an additional binding site in this region is not available. The data also support the suggestion that the ester group of the parent agent is not necessary for binding. A similar inhibition study was made possible by synthesis of 1-(4-biphenylyl)-n-pentyl hydrogen 3-methyl-3-methoxyglutarate. With respect to the corresponding 3-methyl-3-hydroxyglutarate this compound showed an eleven fold decrease of activity. This considerable activity loss indicates that the 3-methoxy group interferes with reversible binding of inhibitor to the enzyme. The inhibition data indicate that the 3-hydroxy group of the 3-methyl-3-hydroxy compound contributes to reversible binding by participating as a hydrogen donor in hydrogen bonding with the enzyme. The major portion of this investigation was designed to probe a region of the enzyme which is nonpolar and binds the n-alkyl moiety of the parent inhibitor. The purpose was to determine the feasibility of incorporating a functional group into this region of the inhibitor which could act as an acceptor for an enzymic nucleophile located in proximity to the reversible binding area. If successful, this could provide irreversible inhibition of the enzyme. A series of compounds was synthesized which bore a terminal alkenyl group two to four carbon atoms removed from the ester moiety. Testing showed that, with respect to the parent inhibitor, no appreciable loss of binding took place. Similarly, a series of epoxyalkyl esters was prepared, the epoxide group being the portion of the inhibitor susceptible to nucleophilic attack. Reversible binding of these compounds was found to be equal to that of the parent inhibitor and it was therefore concluded that the enzyme does accommodate this alkylating group with no loss of reversible binding. This provided the necessary preliminary work upon which subsequent irreversible binding studies will be based.

Neurodegenerative diseases are a class of conditions that lead to progressive atrophy of different parts of the central nervous system (CNS). These diseases lead to devastating clinical outcomes to patients and give rise to an enormous socio-economical burden on society.1 One commonality among some of the most well-known neurodegenerative disorders, e.g. Alzheimer’s disease (AD), Parkinson’s disease (PD), and multiple sclerosis (MS), is neuroinflammation.2-4 Neuroinflammation stems from interactions of the innate immune system with toxins and insults to the central nervous system. In the case of irremovable or chronic insults and toxins, this leads to chronic damaging inflammation that hastens neuronal degeneration and exacerbates disease pathology.5,6 Recently, inflammasomes of the innate immune system have been indicated in playing essential roles in the observed inflammatory responses. The most studied inflammasome is the nod-like receptor pyrin containing 3 (NLRP3) inflammasome.7–9 Recently our research group has successfully developed sulfonamide-based small molecule inhibitors of the NLRP3 inflammasome, such as JC-21 and JC-171, as potential therapeutics for AD and MS. Our studies established that JC-21 is a selective inhibitor of the NLRP3 inflammasome.10,11 Structural modifications led to the development of JC-171 with improved pharmacokinetic properties. More importantly, our studies demonstrated the in vivo activity of JC-171 to effectively ameliorate the experimental autoimmune encephalomyelitis (EAE), a mouse model of MS.12 Our data also strongly suggested that inhibitors based on this chemical scaffold may directly target the NLRP3 inflammasome.10–12 In this dissertation, we conducted biophysical, biochemical, and modeling studies to further elucidate the mechanistic information of these compounds as inhibitors of the NLRP3 inflammasome. In order to conduct further mechanistic studies, the NLRP3 protein was produced via transfection of HEK 293 cells with a modified plasmid of full-length human NLRP3 protein.13 Furthermore, LC-MS studies were conducted to confirm the blood-brain barrier penetration (BBB) of JC-171. Our studies established that JC-171 directly binds to the NLRP3 protein. The results also suggested that JC-171 may bind to the NACHT domain of NLRP3 while in a site that is distinct from the ATP binding site. This notion is supported by the fact that our compounds do not interfere with the ATPase activity of NLRP3. Docking studies of JC-171 to the homology model of the NACHT domain of NLRP3 also supported this assertion by showing the interaction of JC-171 with residues that are not overlapping with the ATP binding pocket. BBB penetration studies in combination with LC-MS analysis confirmed that JC-171 shows better BBB penetration when compared to MCC950. Collectively, our results strongly support that our compounds function as NLRP3 inflammasome inhibitors by directly binding to the NLRP3 protein, a novel and distinct mechanism of action when compared to the known inhibitors that target the NLRP3 inflammasome pathway. These results strongly encourage further development of such inhibitors as potential therapeutics for neurodegenerative diseases.

In 1962, Owen, Dietz, and Camiener reported the isolation of a new antitumor antibiotic from the culture filtrate of Streptomyces sparsogenes. The structure of the crystalline antibiotic, named sparsomycin, remained elusive until 1970, when Wiley and MacKellar reported results of spectroscopic and degradation studies which elucidated the structure. In addition to the molecular structure, investigators have examined the mechanism of action, toxicity, and related analogues, striving to establish sparsomycin or a synthetic analogue's usefulness as an effective chemotherapeutic agent. The initial pharmacological evaluation of sparsomycin revealed it possessed activity against KB human epidermoid carcinoma cells, a variety of gram-negative and gram-positive bacteria, and fungi. This broad spectrum of activity prompted a closer examination of the biochemical mechanisms. These studies revealed sparsomycin interfered with protein synthesis by inhibiting peptide bond formation near the enzyme peptidyl transferase. Ottenheijm, Liskamp, and Tijhuis reported the first total synthesis of sparsomycin in 1979, which provided access to greater quantities of the material for investigational use. Sparsomycin was selected for use by cancer patients in phase I clinical trials, but was found to cause ocular toxicity which hindered its development as an antitumor agent. In an effort to reduce or eradicate the toxic effects while maintaining the antitumor activity, analogues of sparsomycin were prepared. Using the sparsomycin analogues which were synthesized, studies were performed to determine the effect alteration of key structural parameters had on the efficacy of the compounds. Previous investigators examined analogues which incorporated modifications of the uracil ring, the unique mono-oxodithioacetal moiety, and the stereochemical configuration of the chiral centers. Vince and Lee reported there was an apparent requirement for the Q-configuration at the asymmetric carbon atom. Overall, however, the small number of sparsomycin analogues prepared and evaluated limited the definitive statements concerning the functional groups required for antitumor activity. In order to expand and clarify the structure-activity relationships, three series of new sparsomycin analogues were prepared for this project. The compounds of Series I and II, distinguished by the inclusion or exclusion of a hydroxymethyl functional group, were designed to elucidate the effect on activity of replacing the mono-oxodithioacetal side chain of sparsomycin with 4-substituted benzyl groups. The Series III analogues, which excluded the hydroxymethyl functional group, featured a 4-substituted benzyl amide group in place of the mono-oxodithioacetal moiety of sparsomycin, and were designed to investigate the potential interaction of an amide oxygen in contrast to the sulfoxide oxygen of sparsomycin. The target compounds synthesized for this project were experimentally examined to quantitate their effects on [75Se]-selenomethionine incorporation as an 125 cell growth, indirect measurement of protein synthesis, and 5-125I-iodo- 2-deoxyuridine incorporation as an indirect measurement of DNA synthesis in bone marrow, P388 lymphocytic leukemia, and P815 mastocytoma cells. The results for the Series I and II analogues indicated the removal of the hydroxymethyl functional group as seen in sparsomycin affected activity to varying degrees depending upon the assay and the type of cells used. The results for the Series III compounds suggested the removal of the hydroxymethyl functional group and substitution of the mono-oxodithioacetal side chain of sparsomycin with a substituted benzyl amide moiety was not beneficial for activity. Finally, examination of the collective data revealed that the bromobenzyl-substituted analogues consistently imparted the greatest inhibitory activity, while the methoxybenzyl-substituted analogues displayed the least. The methyflnnzyl and the unsubstituted benzyl compounds were intermediate in inhibitory potency. The activity may correspond to the lipophilic and electronic characteristics of the substituents on the benzyl moiety of the analogues. It appears that the bromobenzyl-substituent of hydrophobic and electron withdrawing character is optimal for inhibitory activity, and conversely, the methoxybenzyl substituent of hydrophilic and electron donating character is least desirable.

Human immunodeficiency virus (HIV) and opioid abuse have been described as synergistic epidemics. Pharmacologically, it has been found that opioids have the capacity to enhance HIV infection and replication. Research has shown that activation of the mu-opioid receptor (MOR) elevates the expression of the HIV-1 entry co-receptor CXCR4 on T-lymphocytes in the peripheral nervous system, thus allowing for enhanced viral entry and invasion. Although the exact mechanism for opioid modulation of CXCR4 expression and subsequent exacerbation of HIV is unknown, several hypotheses exist. One hypothesis is that MOR and CXCR4 are functionally interacting through the formation of a heterodimer. This hypothesis is supported by studies substantiating the ability for MOR and CXCR4 to form heterodimers with other GPCRs, and the finding that MOR and CXCR4 were co-expressed in several central and peripheral regions including immune cells. To test this hypothesis, a series of bivalent ligands containing both a mu opioid receptor (MOR) antagonist and a CXCR4 antagonist pharmacophore was designed and synthesized to understand the pharmacological role of the putative CXCR4-MOR heterodimer in opioid exacerbated HIV progression. These bivalent ligands were evaluated for their binding and functional activities in radioligand binding, antibody binding, [35S]GTPγS, and calcium mobilization assays. In these assays, the bivalent ligands were shown to maintain binding and functional activities in both MOR and CXCR4 monoclonal cell lines. In addition, these bivalent ligands were evaluated for their ability to block HIV entry in a reverse transcriptase assay, and for their ability to inhibit morphine exacerbated HIV invasion in an LTR-luciferase assay. In these assays, the bivalent ligands were shown to inhibit HIV entry in a dose dependent manner. However, due to experimental limitations in our morphine exacerbated reporter system, the ability for the bivalent ligands to inhibit viral entry upon morphine co-exposure was not fully validated. Finally, molecular modeling approaches were utilized to visualize the putative binding modes of the bivalent ligands in a constructed MOR-CXCR4 heterodimer model. Overall, these studies have provided a solid basis for the utility of bivalent ligands in studying MOR-CXCR4 interactions and their involvement in opioid potentiated HIV progression. Further studies are ongoing to optimize the bivalent ligands construct and explore new analyses to evaluate their ability to block opioid modulation of the virus.

During the past few decades, analogs of purine nucleosides have been described that are modified either in the heterocyclic base, sugar moiety or both, and many of these modified nucleosides display antiviral and/or antineoplastic activity. The Class II mesoionic purinones are isosteric with their non~mesoionic purinone counterparts. It is conceivable that the mesoionic purinone nucleosides might constitute an entirely novel class of modified nucleosides with potential chemotherapeutic activity. That the mesoionic heterobases are bioisosteric as well as isosteric with non-mesoionic purinones was realized by demonstrating that certain mesoionic xanthine derivatives, such as Anhydro-8-ethylw-5-hydroxy-7-oxo-l,3,4-thiadiazolo[3,2-a]pyrimidinium hydroxide and Anhydro-6-p-chlorobenzyl-8-ethyl-5-hydroxy-7-oxo—l,3,4—thiadiazolo [3,2-a]pyrimidinium hydroxide were comparable in potency to test compound, theophylline as inhibitors of adenosine binding at the A1 site. Three different types of mesoionic nucleosides were subsequently designed and synthesized as potential antineoplastic agents. Mesoionic thiadiazolopyrimidine nucleosides, i.e. Anhydro-6-ethyl-8-(2’,3',5'-tri-O-acetyl-D-ribofuranosyl)MS-hydroxy-7-oxo-l,3,4~thiadiazolo{3,2-a]pyrimidinium hydroxide and Anhydro-8-(2',3'.5’-tri-O-acetyl-D-ribofuranosyl) -5-hydroxy-7-oxo-l,3,4-thiadiazolo[3,2-a]pyrimidinium hydroxide were designed to serve as potential pro-drugs of 2-amino-l,3,4~thiadiazole mononucleotide which has been reported to be a potent inhibitor of inosine monophosphate dehydrogenase. The O~acylated derivatives of the target compounds were prepared by the acid catalyzed condensation of D-ribose with 2-ATD followed by protection of the hydroxyl groups and subsequent cyclization to the mesoionic products; anomeric separation was achieved by column chromatography; All attempts to deprotect the hydroxyl groups of the mesoionic nucleosides resulted in hydrolytic ring-opening of the mesoionic heterobase. The 0-acetyl derivatives of the mesoionic thiadiazolopyrimidine nucleosides were evaluated for antineoplastic activity but were found to be inactive. The mesoionic thia-zolinopyrimidine nucleoside, i.e. Anhydro-6-ethyl-8-(D-2‘-deoxyribo-furanosyl-5-hydroxy-7-oxo-2,3-dihydrothiazolo[3,2-a]pyrimidinium hydrox- ide, prepared in a similar fashion to the mesoionic thiadiazolopyrimie- dine nucleosides, was designed as a potential inhibitor of the enzyme thymidylate synthetase. The mesoionic thiazolinopyrimidine nucleoside, was obtained as the a anomer and was not evaluated for antineoplastic activity. The mesoionic imidazothiazine nucleoside, i.e. Anhydro-l- (2',3',5'-tri-O-acetyl-D-ribofuranosyl)-5-hydroxy-7-oxoimidazo[2,l-b] thiazinium hydroxide was prepared as a potentially useful agent, due to its structural and isosteric similarity with purine nucleosides. The mesoionic imidazothiazine nucleoside was prepared by a cyclization reaction between the tri-0-acetyl-D-ribofuranosyl imidazole-2-thione and carbon suboxide. The mesoionic imidazothiazine nucleoside was not stable at room temperature or in aqueous Solution. While the results of this study on the chemotherapeutic utility of mesoionic nucleosides was rather discouraging, knowledge has been.gained that might be of value for the future design and synthesis of useful mesoionic nucleosides.

No description available.

Aurones belong to an uncommon class of plant flavonoids that provide the bright yellow coloration of some ornamental flowers and that possess a range of biological activities. Structure-activity relationships (SAR) in the aurone pharmacophore identified heterocyclic variants of the (Z)-2-benzylidene-6-hydroxybenzofuran-3(2H)-one scaffold that possessed low nanomolar in vitro potency in cell proliferation assays using various cancer cell lines, in vivo potency in prostate cancer PC-3 xenograft and zebrafish models, selectivity for the colchicine-binding site on tubulin, and absence of appreciable toxicity. Among the biologically active analogs developed in the course of this dissertation work were (Z)-2-((2-((1-ethyl-5-methoxy-1H-indol-3-yl)methylene)-3-oxo-2,3-dihydrobenzofuran-6-yl)oxy)acetonitrile (5a) and (Z)-6-((2,6-dichlorobenzyl)oxy)-2-(pyridin-4-ylmethylene)benzofuran-3(2H)-one (5r). These two aurones 5a and 5r inhibited in vitro PC-3 prostate cancer cell proliferation with IC50 values below 100 nM. A xenograft study in nude mice using 10 mg/kg of 5a for 18 days had no effect on mice weight, and aurone 5a did not inhibit, as desired, the human ether-à-go-go-related (hERG) potassium channel. Cell cycle arrest data, comparisons of the inhibition of cancer cell proliferation by aurones and known antineoplastic agents, and in vitro inhibition of tubulin polymerization indicated that aurone 5a disrupted tubulin dynamics. Based on a National Cancer Institute COMPARE analysis, studies using computer-based molecular docking and liquid chromatography-electrospray ionization-tandem mass spectrometry studies, aurone 5a targets the colchicine-binding site on tubulin. In addition to solid tumors, aurones 5a and 5r strongly inhibited in vitro a panel of human leukemia cancer cell lines and the in vivo myc-induced T cell acute lymphoblastic leukemia (T-ALL) in a zebrafish model. In summary, aurones possess a pharmacophore of considerable potential in the search for new antineoplastic agents for the clinical treatment of human cancers.

Malaria is an infectious, often fatal disease that afflicts nearly 200 million people every year. The disease, characterized by recurring and extreme flu-like symptoms, is caused by the protozoan parasite Plasmodium falciparum. Victims usually contract the disease through a mosquito vector. Chloroquine is a chemotherapeutic that was introduced in the 1940s. For many years the drug was the foremost treatment of malaria, being effective and producing few side effects. Unfortunately, tolerance to chloroquine developed when the parasite evolved a resistance mechanism. Newer drugs have been developed and implemented, but these medicines also show a decreasing effect with continued administration. It is imperative that a new pipeline of drugs be developed in order to combat the disease and anticipated resistance. Reversed chloroquines are a new class of multiple-ligand compounds that are active against chloroquine-sensitive and chloroquine-resistance malaria species. This thesis describes research targeted at the modification of lead reversed chloroquine molecules to discover new and effective moieties, as well as to improve pharmacokinetic-related properties. An especial emphasis of this project is the addition of a sulfonamide functional group to a reversed chloroquine. Preliminary evidence indicates that this is a promising direction for this line of research. Brief discussions of some reversed chloroquine characterization studies are included in appendices.