Chemistry Commons^™

Isolation And Characterization Of Novel Arginine-Derived Heterocyclic Amines, Nathaniel Srikureja

Honors Theses

Most known heterocyclic amines (HCAs) are potent mutagens present at significant concentrations in cooked meats, and can be synthesized from burned mixtures of L-creatin(in)e with various amino acids. We hypothesize that novel mutagenic HCAs may be synthesized from a heated plant-based food simulating binary amino acid mL'\:ture: L-arginine and L-threonine. A two-part solid phase extraction was used to separate nitrogen heterocycles from byproducts followed by prep­ HPLC and the Ames mutagenicity assay using Salmonella TA98 to determine the mutagenicity of various isolates. The results indicate that this binary amino acid mixture does not yield a mutagenic sample.

Synthesis Of An Ideal Inhibitor For The Lpxc Enzyme, Taejun Lee

Honors Theses

Due to the growing need of antibiotics in modern day medicine, this study attempts to apply a method of medicinal chemistry that would create a novel inhibitor for a lesser known target of gram negative bacteria, the LpxC enzyme. This study proposes that a synthetic plan which consists of combining components of different molecules would create a more effective inhibitor. These components include a binding group for the active site of the enzyme, a hydrophobic chain which has been shown to interact with an allosteric site on the LpxC enzyme, and the isoxazoline ring which interacts with the zinc ion. …

Analysis And Review Of The Effects Of Bacterial Competition On Efflux Pump Inhibition, Robert Leszcynski

Honors Theses

Multidrug resistant antibacterial strains are a dangerous problem for modern medical professionals. When cells of two different strains are grown together, they must compete with each other for nutrients. This competition can lead to the production of harmful compounds that are toxic to the competing strain. One such compound may be a compound that inhibits the efflux of antibiotics from the cell. When the cells compete with one another, one or both of the cells will produce compounds that are harmful to the competing strain.

Tracking Disparate Colony Morphological Trends With Thermus Scotoductus, Matthew P. Leverick

Honors Theses

When plating most mesophilic bacteria, the colony shape, size, and color tends to be uniform when a single strain is present. When plating defined cell densities of T. scotoductus, however, the colonies were not of uniform size and shape while it grew on the surface. In this project, we sought to observe trends in colony morphology (shape and size) changes using the thermophile Thermus scotoductus on nutrient rich agar plates at 60°C. A general planktonic growth curve was also created to help characterize the activity of this bacterium. This project was our first attempt to characterize if this unusual phenomenon …

Boron Dipyrromethenes: Synthesis And Computational Analysis, Eduardo Rivé Lockwood

Honors Theses

Recently, there has been a growing interest in the boron dipyrromethene (BODIPY, 4,4′- difluoro-4-bora-3a,4a-diaza-s-indacene) compounds. BODIPY compounds have fascinating properties that allow for the absorption and emission of light in the near infrared region of the electromagnetic spectrum. These molecules are highly modifiable making them ideal chemicals for the use of photoelectric energy conversion such as for commercial use in dye sensitized solar cells (DSSCs). It has been previously shown that different meso compounds have only a slight effect on the absorptive capabilities of these BODIPY compounds. We believe that the BODIPY compounds’ lack of planarity is one of the …

Identifying Natural Inhibitors Of Bacterial Efflux Pumps, Marrisa Therriault

Honors Theses

Antibiotic resistance is a constantly progressing epidemic. Many strains of bacteria have developed a resistance to antibiotics, resulting in prolonged sickness and death. Resistance can be to a specific drug (single drug resistance) or to multiple drugs (multi-drug resistance). This resistance can be caused by a tripartite protein pump called an efflux pump that extends through the inner and outer membranes of the bacterium to pump antibiotics from the inside of the cell to the extracellular environment. In E. coli the efflux pump is called AcrAB-TolC. In the efforts to combat this problem, this experiment focuses on the inactivation of …

Structural Investigations Using Theoretical Approaches : A Study Of Metal Halides, Borylenes, Phenalenyl Complexes And Σ-Hole Interactions, Supreeth Prasad

Honors Theses

The anomalous bending in the group 2 binary dihalides and the absence of this behavior in group 12 systems is well established. Their structuralpreferences contradict simple bonding models, yet they have received little to no attention in the literature. In this work, for the first time, the gas phase structuralpreferences of the groups 2 and 12 mixed (ternary) dihalides MXY (M=Be, Mg, Ca, Sr, Ba, Ra, Zn, Cd and Hg,and X, Y=F, Cl, Br, I, At) are investigated at high levels of theory. I extend a previously established softness criterion for bending to the mixed systems and I find that …

Detecting Cyanobacteria Toxins: The Human Health Impact Of An Environmental Problem, Lillian E. Naimie

Honors Theses

Cyanobacteria blooms are a growing concern in the world, as they can form a dense and sometimes toxin scum on water bodies. This paper will outline and discuss the environmental conditions that produce cyanobacteria bloom with a focus on the toxins produced by blooms and specifically the detection of these toxins through two analytical methods. Of the various toxins cyanobacteria are capable of producing, this paper will focus on microcystins and BMAA, a family of hepatotoxins and a specific neurotoxin respectively. The two analytical methods discussed are liquid chromatography coupled mass spectrometry and ELISA kit techniques. The advantages and drawbacks …

Generation And Reactions Of Cyclopropyl Vinylidene Carbenes, Nguyen Nhat Thu Le

Honors Theses

This study aimed to generate cyclopropyl methyl vinylidene carbene and cyclopropyl phenyl vinylidene carbene via photochemical routes. The precursors to these two carbenes were synthesized from phenanthrene by a two-step procedure. However, these precursors could not be fully purified because the second step generated many side products with similar properties as the precursors. A crude sample of each precursor were photolyzed with UV light in the range of 315 to 400 nm. Vinylidene carbenes are known to rapidly rearrange into alkynes, so the formation of these cyclopropyl vinylidene carbenes was monitored through the formation of their rearrangement products, cyclopropyl methyl …

Solvation Of Isoelectronic Halide And Alkali Metal Ions By Noble Gas Atoms, Carly A. Rock

Honors Theses

Alkali metal cations (M+ = Li+, Na+, K+, and Rb+), as well as their corresponding isoelectronic atomic anions (X− = H−, F−, Cl−, and Br−) were solvated with argon atoms (i.e., M+Arn and X−Arn where n=1−6). Full geometry optimizations were performed using the MP2 electronic structure method with a series of correlation consistent basis sets augmented with diffuse functions on argon and the anions (aug-cc-pVXZ) and weighted core valence basis sets were used for the cations (cc-pwCVXZ) that include the appropriate pseudopotentials for K+ and Rb+ (cc-pwCVXZ-PP). The basis sets for a particular cluster are, hereafter, simply denoted as XZ …

Synthesis Of A Novel Tetradentate Ligand And Its Copper Complex For Redox Shuttle Applications, Joseph T. Vaughan

Honors Theses

With growing energy demands, alternatives to the traditional non-renewable fuel sources are currently being explored. Of these alternative fuel sources, solar energy, particularly dye-sensitized solar cells (DSSC), have garnered considerable interest. Traditional redox mediators within these solar cells have been triiodide/iodide couples, which pose several complications due to their corrosiveness, absorption in the visible range, and efficiency, motivating the development of better redox couples for next generation DSSCs. Thus, transition metal complexes have rapidly gained traction as a potential replacement for this traditional I-/I3- based system. In this study, a novel tetradentate ligand framework and its copper and nickel complexes …

Design And Development Of Chemically And Biologically Stable Salvinorin-Based Ligands For Opioid Receptors, Tanner Neilson

Honors Theses

The number of opioid prescriptions as a method in pain management increased dramatically in the mid 1990’s following Dr. James Campbell’s 1995 Presidential address to the American Pain Society, where he called for patient pain to be included as a vital sign. The rapid increase in prescriptions in the early 2000’s coupled with a massive effort by pharmaceutical companies to downplay the addictiveness of these drugs has led to a consistent increase in opioid-related drug overdoses, with 47,600 of 70,237 drug related deaths involving opioids in 2017. Opioid analgesics most commonly act upon the mu-opioid receptor (MOR), which is one …

Unexpected Outcomes During The Attempted Iodination Of Biphenol, Henry Nguyen

Honors Theses

The goal of this research was to create a new procedure to iodinate 4,4- biphenol using a ball miller. Iodination of 4,4-biphenol was first attempted in solution using electrophilic aromatic substitution. Several attempts were made to iodinate 4,4-biphenol, but the general insolubility of crude products inhibited progress. Interestingly, NMR analysis of the aqueous ammonia product suggested that 4,4-biphenol dimerized or polymerized with itself to make an ether. The exact mechanism by which the ether dimer was created is unknown, but the reaction may have occurred using a radical mechanism. Though the original goal of the project is left unmet, a …

Cigarette Litter Leachates: A Statistical Study Of Elements In Freshwater And Saltwater, Cintly Guzman Hernandez

Honors Theses

Cigarette butts are the most common item found in coastal litter cleanups as approximately 4.5 trillion smoked cigarette butts are discarded into the environment every year. Cigarette butts can leach toxic heavy metals and nicotine along with other compounds from tobacco combustion. Past research in our lab has analyzed elements leached from cigarette butts into freshwater. The cigarette butts consisted of smoked and unsmoked butts that were soaked varying periods of time, and at different pH levels to identify the relationship of these variables to the amount of metal leached. The elements analyzed were Al, Ba, Cd, Cr, Cu, Fe, …

Community-Based Research Methods To Inform Public Health Practice And Policy: The Case Of Lead In The Mississippi Delta, Mary Alexandra Fratesi

Honors Theses

Environmental health issues are complex and require interdisciplinary and community engagement approaches to better understand them and inform policy. As one example, lead exposure has a number of dangerous neurological effects, including developmental delays and learning deficits. Potential lead exposure through drinking water and paint are areas of concern. In a 2018 document, the Environmental Protection Agency (EPA) estimated that up to 20% of lead exposure comes from drinking water alone. By using a type of engagement research called community-based research (CBR), this project began to address this major public health issue. CBR can be used to connect residents, their …

Electro- And Photocatalytic Carbon Dioxide Reduction With Mononuclear And Dinuclear Rhenium Polypyridyl Complexes, Eva Amatya

Honors Theses

The main challenge of reducing carbon dioxide (CO2) to value-added products lies in designing more efficient catalysts that are long-lived, selective, and operate near the thermodynamic potential for the reaction. In this work, mononuclear and dinuclear Re complexes containing diamine ligands linked to a pendant anthracene moiety have been synthesized and studied for both electrocatalytic and photocatalytic CO2 reduction. Electrocatalytically, the performances of both catalysts were studied in N,N-dimethylformamide (DMF) and acetonitrile (MeCN) solutions to determine their turnover frequencies (TOFs) for CO2 reduction. Catalyst performance was compared to previously reported rhenium systems, and both systems studied here were shown to …

An Exploration Of Pyrrole Groups On The Enantioselectivity Of Pig Liver Esterase, Brian Long

Honors Theses

Pig Liver Esterase (PLE) is a serine protease enzyme that can interact with one side of a diester to hydrolyze the ester to a carboxylic acid, and research has found that the level of hydrophobicity of side groups can impact the enantioselectivity of PLE hydrolysis.1, 2 The Jones Model is what current researchers use to model the active site of PLE, but the nature of its binding pockets, namely the Hydrophobic Long (HL) pocket, has been called into question.3 Dimethyl 2-((pyrrole-2-yl)methyl)-2-methylmalonate was prepared to be subjected to PLE hydrolysis to see whether enantioselectivity was found. Chiral HPLC revealed 25.32% enantiomeric …

Pro-Antimicrobial Networks Prepared Via Degradable Thiol-Ene Acetal Photopolymerization, Sarah Swilley

Honors Theses

A degradable, antimicrobial polymer network with acetal crosslink junctions derived from p-anisaldehyde (pA), a common constituent found in star anise extract, is reported. The p-anisaldehyde was converted into a bis-functional acetal alkene monomer, which serves as a pro-antimicrobial form of the active aldehyde and a building block for materials referred to as pro-antimicrobial polymer networks via degradable acetals (PANDAs). Subsequently, the bis-functional acetal alkene monomer was photopolymerized with a multifunctional thiol to yield a thiol-ene network. PANDAs exhibit surface erosion behavior and yield sustained release of pA over 38 days when exposed to neutral or biologically relevant conditions. The pA …

Investigation Of The Effects Of Hydrogen Bonding On The Enantiomeric Excess Of Pig Liver Esterase Hydrolysis Products, Matthew Hasler

Honors Theses

Pig Liver Esterase (PLE) is an effective enzyme used in the Masterson Research Group due to its ability to hydrolyze only one ester in a malonic diester. PLE is employed for creating chiral molecules for the synthesis of unnatural amino acid precursors. Previous research in the group found that malonic half esters with hydrogen bonding capable substrates yielded varying degrees of enantiomeric excess, and non-hydrogen bonding substrates yielded racemic mixtures.1,2 The compounds synthesized contained substrates consisting of thiophene rings in the second and third position, and these molecules act as a control for the other research done in the group. …

Understanding The Coating-Substrate Interface Changes And Degradation Caused By Environmental Acclimation With Water And Electrolytes, Russell Vick

Honors Theses

While it is well known that polymeric coatings are used to protect metals from corrosion, efficient and reliable protocols for quantifying and estimating protective coatings’ lifetimes have yet to match real-time results in rate or in detected mechanisms of material failure. Alkoxysilane pretreatments are widely utilized for substrate preparation and improved coating system performance by changing the metal substrate surface morphology to improve adhesion at the coating-substrate interface by creating a foundation and excluding water from the system. Three pretreatments used were 3-aminopropyltriethoxy silane (APS), tetraethylortho silicate (TEOS), N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAS). They were investigated to improve the understanding of the relationships …

Photoelectrochemical Investigations On Novel Earth Abundant Solid State Catalysts For Solar Water Oxidation, Nathaniel Branimir Kurtz

Honors Theses

In light of a looming fossil fuel scarcity, many forms of alternative, clean energy production are being researched in order to provide a more sustainable source of energy production for the future. One area of research is on using novel, abundant catalytic materials in conjunction with semiconducting materials to drive the splitting of water in order to produce hydrogen gas, an energy-rich fuel. Currently, efficiency is limited by the energy bottleneck posed by the oxygen evolution reaction (OER) half of water splitting. In this work, cobalt selenide (CoSe) catalyst paired with the semiconductor iron oxide (Fe2O3) has been identified as …

Diastereoselective Synthesis Of 2,4,6-Trisubstituted Piperidines Via Aza-Prins Cyclization, John A. Hood

Honors Theses

The nitrogen heterocycles are shared amongst 59% of Food and Drug Administration (FDA) approved small molecule pharmaceuticals with the six-membered piperidine representing the most common moiety. Given the versatility and potential to yield derivatives with broad biological activities, the discovery of new chemical methods to generate these heterocycles in a more time and cost-efficient manner is desired. While there are existing racemic methods to access this class of molecule, the objective of this research is to pioneer a new novel six-step method to generate 2,4,6-trisubstituted piperidines with stereoselective control.

The first step is a condensation between a nonenolizable aldehyde and …

Biocompatible, Responsive Polysoaps Via Raft Copolymerization For The Delivery Of Model Cancer Therapeutics, Mason Dearborn

Honors Theses

Many chemotherapeutic drugs are small, hydrophobic molecules that require water-soluble, biocompatible nanocarriers for enhanced vascular circulation. Existing polymeric carriers either conjugate the drug along a copolymer backbone or sequester drugs within a protected interior domain to be delivered to specific sites in the body. Such therapeutic systems must overcome a myriad of hurdles, beginning with complex, multi-step syntheses, followed by other inherent barriers that limit the efficiency of drug delivery at the targeted site. This work aims to circumvent a number of these issues using biocompatible, stimuli-responsive polysoaps that are capable of unimeric micelle formation, hydrophobic drug delivery, and triggered …

Phospholipid Membrane Remodeling Through Exogenous Fatty Acid Incorporation In Certain Bacterial Species, Josh Herndon

Honors Theses

Multi-drug resistant bacteria have become problematic in healthcare settings. Recent studies have documented the ability of some bacteria, such as Vibrio species, to assimilate exogenous fatty acids into their membrane phospholipids. Therefore, the current research was performed to determine whether the three virulent, multi-drug resistant bacteria Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli can remodel their cell membranes following exposure to a range of exogenous polyunsaturated fatty acids (PUFAs). Furthermore, we hypothesized that PUFAs would influence phenotypes associated with growth and virulence. Extracted phospholipids were examined by UPLC/MS analysis to confirm assimilation of exogenous PUFAs into the bacterial phospholipids. A. …

Sds-Page Analysis Of Modified Lysozyme By Substituted Benzoquinones And Naphthoquinones, Neethu Kurien

Honors Theses

Quinones are molecules that are commonly found in the environment, as cofactors for proteins or an electron carrier in the mitochondrial electron transport chain. However, quinones also can come from polycyclic aromatic hydrocarbons as their metabolites, harming cellular integrity. In this study, we investigated protein modification of lysozyme in the presence of substituted benzoquinones and naphthoquinones. To simulate physiological conditions, all reactions used phosphate buffer (50.0 mM). While the majority of the experiments were performed at 37 C and pH 7.0, there were also temperature dependence (27 C and 42 C) and pH dependence (6.0 and 8.0) reactions included. SDS-PAGE …

Synthesis Of Oxygenated Boronic Acid Substituted A-Cyanostilbenes For Use As Antibacterial, Yewon Kim

Honors Theses

Stilbenes are naturally occurring compounds that have exhibited antibacterial activity, although the biological effect of various stilbenes differs for Gram-positive and Gram-negative strains of bacteria. In prior research, cyanostilbenes have shown slight antibacterial activity (Brownlee, et al. 1943). This project aims to explore whether hybrid oxygenated a-cyanostilbenes possessing a boronic acid pharmacophore exhibits significant antibacterial activity (Das et al. 2013). The biological activity against Staphylocococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) was tested using the Kirby-Bauer text. No inhibition of E. coli growth was shown while S. aureus was partially inhibited.

Evaluating Mutagenicity Of Burned Arginine-Based Heterocyclic Amines And Anti-Mutagenicity Effect Of Chinese Medicinal Herbs, Rayford C. Alva

Honors Theses

From the unexpected finding that cooked grains and meat substitutes elicit a mutagenic response in Salmonella typhimurium TA98, our work has been aimed at deconstructing this finding via a survey of heated binary amino acid combinations, involving arginine, a plant-based amino acid. secondly, our work has looked towards sing phytochemical extracts from traditional Chinese medicinal herbs to inhibit the mutagenic activity of heterocyclic amines (main culprit for mutagenicity in meat). Two fractions from the burned products of arginine and phenylalanine (RF-HCA-06 and -07) were statistically significant inducers of mutagenesis; Scutellaria barbata and Oldenlandia diffusa, both separately and together, were statistically …

The Impact Of The 515nm Effect On 1o2 Quenching In Photosynthesis: Model System Studies Using Β-Carotene–Acid Complexes, Lauren A. Hoody

Honors Theses

β-carotene (βC) is an orange pigment present in the photosynthetic reaction center (PRC) of green plants, where it plays a vital role in photosynthesis: It quenches singlet oxygen (1O2 , a toxic oxidizing species generated during photosynthesis) before the 1O2 damages chlorophyll and other components of the PRCs. During photosynthesis, βC temporarily converts from its native orange–450 state to a pink–515 state via the so–called 515nm Effect. Because of the differences between the electronic structures of orange–450 and pink–515, I hypothesize that pink–515 will quench 1O2 less efficiently than orange–450. This hypothesis has not been tested to date because orange–450 …

Presence And Potential Sources Of Pharmaceutical And Personal Care Product Chemicals In Messalonskee Lake, Alyssa T. Kullberg

Honors Theses

Pharmaceuticals and personal care product chemicals (PPCPs) represent a large group of contaminants that are mostly not regulated in surface or drinking water and whose presence and environmental and health impacts are poorly understood. We investigated the presence and potential sources of 18 PPCPs in Messalonskee Lake. We collected samples four times over the summer of 2017 at 13 sites around the lake. Samples were tested for PPCPs using liquid chromatography-tandem mass spectrometry. We detected five out of the 18 PPCPs we tested for at the ng/L level: caffeine, 1,7-dimethylxanthine, acetaminophen, sulfachloropyridazine, and amphetamine. PPCPs showed a significant positive correlation …

Stable Bromine Isotope Signature Of Bromoform From Enzymatic And Abiotic Formation Pathways And Its Application In Identifying Sources Of Environmental Bromoform In The Damariscotta River, Chengyang Wang

Honors Theses

Bromoform is a major source of atmospheric bromine. Most bromoform is produced by marine organisms including macroalgae and phytoplankton, using the enzyme bromoperoxidase (BPO). Bromoform can also be a byproduct of industrial processes such as water disinfection. Identifying sources of environmental bromoform is still a challenge. A novel technique of using quadrupole mass spectrometry coupled to a gas chromatography (GCqMS) was developed and optimized for Br isotope analyses. The study shows that GCqMS in single ion monitoring (SIM) mode can measure 81Br with precision of around ±0.7‰ (60pmol bromoform injected). This study aims to investigate stable Br isotopes of bromoform …