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Chemistry [clear filter]
Tuesday, April 24
 

12:00pm PDT

Importance Of Isoleucine 55 For Rotor-Stator Interactions In E Coli F1FO ATP Synthase
ATP synthase, a ubiquitous biological nanomachine, is responsible for synthesizing the majority of adenosine triphosphate (ATP) in cells. The process of synthesizing ATP uses a unique rotary mechanism, which involves two motors, F1 and FO where protons get translocated in FO. Cryo-electron microscopy (cryo-EM) maps have given insight into the structure of Escherichia coli (E. coli) ATP synthase; however, they do not explain the intricacies of how protons drive rotation. Previous studies showed that proton translocation occurs at the subunit a/c interface (located in FO) and that some amino acid residues are important for function; among these is isoleucine 55 of subunit c (cI55). We are trying to elucidate what chemical properties are essential for functionality at position 55, which is located on the second transmembrane helix (TMH2) of subunit c. Changes in the side chain will be imposed using site directed mutagenesis and chemical modifications via methanethiosulfonate and functionality observed using fluorescence spectrometry. Replacing isoleucine with alanine (cI55A) resulted in H+ pumping that behaves similarly to that of the wild type. This result leads us to believe that steric bulk is not an essential property at this position, and we are currently looking at the importance of hydrophobicity.

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Tuesday April 24, 2018 12:00pm - 1:00pm PDT
Sherrill Center Concourse

12:00pm PDT

Analysis And Investigation Of Aziridines
This research examined, aziridines and their properties. Although aziridines are structurally similar to Beta-lactams, a broad group of antibiotics, they are more unstable. Investigating aziridines as a modification of Beta-lactams could give more insight into the functionality of Beta-lactams and open up a potential new branch of antibiotics. The Department of Chemistry at the Science University of Tokyo used the Corey-Chayovsky Aziridation Reaction to investigate the enantioselective synthesis of aziridnes from amines and alkyl halides by using camphor-derived chiral sulfide mediator. Thus, demonstrating the aziridation of imines with alkyl bromides with the imino Corey-Chayovsky reaction under the conditions of a chiral sulfide. These findings give more possibilities of modification for the proposed research. The proposed study was to investigate 2-phenyl-1-(3,4,5-trimethoxybenzyl) aziridine. The starting reaction of benzylamine and 3,4,5-trimethoxy benzaldehyde was used to create the imine, (E)-1-phenyl-N-(3,4,5-trimethoxybenzyl) methanimine. After this first reaction, the (E)-1-phenyl-N-(3,4,5-trimethoxybenzyl) methanimine was reacted with a carbene to create 2-phenyl-1-(3,4,5-trimethoxybenzyl) aziridine.


Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Glucuronidation Of 3-Phenoxy Benzoic Acid
3-Phenoxy Benzoic Acid (3-PBA) is a major metabolite of multiple pyrethroids, the active compound in a majority of household insecticides. Pyrethroids act as a neurotoxin and are lethal to many environmentally important insects, can affect aquatic animals such as fish and neurological symptoms and behavioral changes have been seen in mice with developmental exposure to pyrethroids. In vivo metabolism of pyrethroids has not been thoroughly studied in humans, however, animal studies suggest they are commonly metabolized via phase I oxidation and hydrolysis followed by phase II glucuronidation. In this study, the metabolism and inhibition of 3-PBA will be examined using UDP-glucuronosyltransferase (UGT) supersomes. 3-PBA undergoes glucuronidation by UGT1A9 and is expected to fit the Michaelis-Menten kinetic model, with known inhibitors of UGT1A9 decreasing enzymatic activity. This will be determined through kinetic data acquired via High Pressure Liquid Chromatography - Ultraviolet detection (HPLC-UV) analysis of enzymatic assays, which incubate the supersomes with 3-PBA and inhibitor. Acquiring this data will aid in improving our understanding of pyrethroid metabolism and any activity the potential inhibitors have on 3-PBA glucuronidation. Inhibitory activity could lead to an increased half-life of this metabolite in vivo, which could result in negative effects on human health.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Glucuronidation Of Mono(ethylhexyl)-phthalate, Mono(ethyl-hydroxy-hexyl) phthalate, And Uridine-5'-diphospho-glucuronosyltransferase-1A1 Inhibition Via Over-The-Counter Drugs
Phthalates, a di-substituted benzylic family of chemicals with various industrial applications, is a known androgen disrupter that causes severe defects in sexual development when a fetus is exposed in utero. Despite being regulated in many countries, excluding the United States, most people have a base level of phthalate contamination despite the fact that it is not a naturally occurring chemical. Elimination of phthalates requires a Phase II metabolic pathway called glucuronidation, which varies both in an individual and between individuals. This pathway is aided by enzymes from the family of uridine 5'-diphospho-glucuronosyltransferases (UGTs), specifically UGT1A1 and UGT2B7, that allow the environmental toxicants to be excreted via urination. If glucuronidation is inhibited by the common over-the-counter drugs (OTCs) investigated in this study, phthalates would remain in the system for extended periods of time as the primary and more toxic metabolite, exacerbating any harmful side effects of this compound in vivo. Though there are several phthalate derivatives, mono(2-ethylhexyl) phthalate (MEHP), mono(ethyl-hydro-hexyl) phthalate (MEHHP) and mono(butyl) phthalate (MbP) and their interactions with UGT2B7 were targeted specifically. Enzyme kinetics were determined using the Michaelis-Menten model (Vmax, Km apparent, and Ki) for UGT2B7. Enzyme activity and inhibition was evaluated via biochemical assays using UGT Corning Supersomes™ and UGT Reaction Mix Solutions A & B. The resulting solutions were then analyzed via Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS) to determine the levels of glucuronide and substrate.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Isolation Of Novel Antibiotic Compounds From Bacteria
Currently there are approximately 17 million death annually from bacterial infections. A large part of this is due to how rapidly antibiotics are becoming ineffective. It is crucial that new antibiotics, and new ways to discover antibiotics, are found before existing treatments are ineffective. In the Wolfe research group we aim to solve this problem through natural product isolation. Four bacteria, designated as 615(unknown), 655(Serratia), 674(Serratia), and 699(unknown), have been found to produce antibiotic compounds in our in-house high throughput screen. Once growth and antibiotic compounds were optimized, the four bacteria were scaled up to 6L. The natural products were separated using liquid-liquid extraction, purified through column chromatography, and identified using IR/NMR/MS.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Method Development For Kinetic Analysis Of The Glucuronidation Of Equol
Equol is a nonsteroidal phytoestrogen metabolized by intestinal bacteria from daidzein, an isoflavone found in high concentrations in soy products and other legumes. The ability to produce equol only occurs in 30-50% of humans and has been hypothesized to result in greater health benefits via its affinity to -estrogen receptor. Calibration curves were made to determine lowest levels of detection using HPLC UV-Vis. Concentrations below 1ppm were not detectable and thus required LC/MS/MS. An ongoing time-study was also performed, looking at the stability of equol in a solution of 50% v/v H20/MeOH when left at ambient temperatures. Weekly analysis of a 50ppm concentration was performed using HPLC UV-Vis. The kinetics of the isoflavone daidzein will be studied using assays of recombinant Corning® Supersomes™ enzymes. Both the conjugation and deconjugation of glucuronide to equol are of interest, with various added substrates to determine possible inhibitors. The Michaelis-menten model for kinetics will be followed to measure the results. An understanding of what factors affect the rates of glucuronidation of equol may contribute to our ability to derive more efficacious health benefits.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Photodegradation Of Organic Molecules On Titanium Dioxide Nanoparticles Surfaces
In recent years, groundwater contamination of organic compounds has become a growing concern. A possible solution to this problem is to degrade these organic molecules into safer molecules using titanium dioxide, TiO2, catalysts. To enlarge the catalytic efficiency by increasing surface area, considerable research has gone into generating TiO2 nanoparticles (NPs). The least researched polymorph of the TiO2 crystal structures is brookite. This research looked into the methods behind synthesizing TiO2 brookite phase NPs. Brookite TiO2 NPs were synthesized using a hydrothermal method and were then characterized using scanning electron microscopy and Powder X-ray Diffraction along with IR Spectroscopy. The synthesized nanoparticles had a fractal style shape and were monodispersed in size. This method was done once showing a possible reproducible method.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Phytoestrogen And Sugar Analysis In Endangered Sarracenia rubra Ssp. jonesii Populations
Sarracenia jonesii (mountain sweet pitcher plant) and Sarracenia rubra are endangered pitcher plants found in mountain bogs in western North and South Carolina. Due to their carnivorous diet, pitcher plants often reside in low nutrient, wetland environments, and are susceptible to competition from other, nutrient loving plants. This study will sample Sarracenia jonesii and Sarracenia rubra fluids for sugar levels and phytoestrogen levels in order to assess plant health across different colonies. Phytoestrogens are plant derived phenolic compounds with bioactive properties, as well as roles as secondary metabolites within the plants themselves. Ranging from defense against pathogens, determining plant color, or increasing UV resistance, the wide range of functions displayed by these compounds provides the possibility to utilize them to assess plant health within its environment. This research will observe endangered Sarracenia jonesii pitcher plants by measuring sugar levels within enzymatic fluids, and detecting for measurable levels of phytoestrogens as an indicator of plant stress. Across several colonies within Western North Carolina, comparisons will be made as to what factors contribute to a successful colony of Mountain Sweet pitcher plants.


Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Study Of The Degradation Of Trichloroethylene With Titanium Dioxide Nanoparticles
The pollution of different water sources has become an increasing problem over the last few years. This can possibly be counteracted through the use of titanium dioxide (TiO2) nanoparticle catalysts. This reactions occurs primarily through photocatalysis. There are three different shapes of TiO2 that are being tested: anatase, rutile, and brookite. Of these three types, brookite is the least known and was the focus of this study. First, a calibration curve had to be created to track the degradation of Trichloroethylene (TCE) using a gas chromatography-mass spectroscopy (GC-MS). This was originally done for anatase and rutile nanoparticles, and compared to existing literature. Then, these results were compared to that of brookite nanoparticles.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Substituent Effects Of Carbene-HX Complexes On Binding And Isomerization Energies
Hydrochlorofluorocarbons (HCFCs) are a class of compounds in use as refrigerants, foam-blowing agents, etc. that are destructive to the environment as greenhouses gases, often with high ozone depletion potential. This research deals with the decomposition of these compounds including decomposition into novel gas-phase carbene complexes that may persist through subsequent isomerizations to alkenes. Substituents were surveyed computationally for their effects on these complexes to identify potential systems in which they have experimental relevance. It was found that donating groups on the carbene and higher polarity on the leaving HX contributed to the strongest binding affinity and lowering of isomerization energy. These findings indicate a direction for which systems may be best suited for experimental study as well as having broader implications in aiding the study of non-covalent interactions in different settings.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Synthesis And Antibacterial Evaluation Of Empetroxepin A And B And Related Analogs
The World Health Organization recognizes antimicrobial resistance (AMR) as a global problem caused by the decreasing effectiveness of conventional antibacterial drugs. Estimates are that by 2050, 10 million lives a year would be at risk from drug-resistance infections. The Wolfe research group works to develop novel antibiotics through the isolation, extraction, and characterization of secondary metabolites produced by bacteria, and by leveraging antibiotic scaffolds provided by nature to synthesize and optimize antibacterial activity through medicinal chemistry techniques. Empetroxepin A and B, isolated from the black crowberry tree, Empetrum nigrum L. (Ericaceae), exhibited weak antimycobacterial activity against M. tuberculosis H37Ra (MIC = 100 µg/mL, IC50 =25.7 µg/mL and IC50 = 28.5 µg/mL) and selectivity against human embryonic kidney 293 cells (IC50 45.6 µg/mL and IC50 96.7 µg/mL). Although this activity is modest, sufficient structural similarities exist with known bioactive molecules such as depsidone, flavin, and chalcone, suggesting that activity might be enhanced through modifications to the empetroxepin core. Prior research resulted in a synthetic strategy for both empetroxepin analogs by forming an alkene bridge between a triphenylphosphate salt and a trimethylsilane (TMS) protected salicylaldehyde followed by cyclization using potassium carbonate and a copper oxide catalyst . This research investigates the effect of new ligands to the empetroxepin core by introducing commercially available substituted salicylaldehydes chosen for their influence on steric and electrochemical properties. Each empetroxepin analog will be tested for antibacterial activity against a panel of two Gram-positive (S. aureus and B. subtilis) and two Gram-negative (E. coli and P. aeruginosa) bacteria.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Synthesis And Antibiotic Evaluation Of Bedaquiline Analogs That Target ATP Synthase In Escherichia coli
Emergence of drug-resistant bacteria represents a high, unmet medical need, and the added lack of antibacterial agents with novel mechanisms of action only compounds this issue. Gram-negative bacteria, such as Escherichia coli (E. coli), are representative of this need as their treatability is particularly difficult due to the addition of a thick outer membrane and high levels of molecular machinery such as drug efflux pumps to diminish antibacterial activity. ATP synthase has been validated as an antibacterial target in Mycobacterium tuberculosis, where its activity can be specifically blocked by the novel drug, Bedaquiline (BDQ). However, potency of BDQ is restricted to mycobacteria with little or no effect on the growth of other Gram-positive or Gram-negative bacteria. Here, we identify the differences in the ATP synthase amino acid sequence of each pathogen and synthesize analogs of BDQ that target specifically target ATP synthase in E. coli. Using electrophilic aromatic substitutions reactions, a variety of C2 BDQ analogs are being synthesized and evaluated for ATP synthase inhibition using a ATP-driven H+ pumping assay in inside-out membrane vesicles. Development of the diarylquinolines class may represent a promising strategy for combating Gram-negative pathogens.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Synthesis Of Novel Carbazole Analogs And Evaluation Of Their Cytotoxicity
Carbazoles are aromatic heterocyclic compounds that contain similar core compound structure and functional groups as Combretastatin A-4 and colchicine which are tubulin-inhibiting anticancer drugs. Tubulin inhibitors function as antimitotic agents by arresting the growth cycle of cancer cells. Carbazoles have exhibited cytotoxicity of cancer cells by the inhibition of DNA topoisomerase II through intercalation of DNA and the formation of covalent adducts. With the application of carbazoles as rather new anticancer drugs, there are opportunities to investigate the effects of various moieties within the drug, namely electron-withdrawing and electron-donating, on the efficiency of cytotoxicity via Methylthiazol Tetrazolium Assay (MTT). The carbazole analogs will be synthesized in a series of steps involving a substitution reaction and an Aldol condensation to yield the 3,4,5-trimethoxyphenyl vinyl azide ester. The second ring closure to form the indole will be performed by thermal cyclization of the vinyl azide. Finally, a Wittig reaction followed by 6π electrocyclization will close the third ring where variable nucleophilic aromatic substitutions will occur. These carbazole analogs will have the 3,4,5-trimethoxyphenyl group and two biaryl rings of Combretastatin A-4 and colchicine and thus, can be examined for anti-tubulin activity.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Synthesis Of β-Lactam Analogues Of CA-4
This research examines the synthesis of β-lactams as combretastatin A-4 (CA-4) analogues and their ability to target and bind to tubulin within cancer cells. Tubulin is an α, β heterodimeric protein and is an important and promising target for cancer research because cell division relies on tubulin and without it, cell division cannot occur. CA-4 is a naturally occurring compound, isolated from the South African bush willow Combretum Caffrum, and is an important molecule to study because CA-4 can bind to tubulin within cells. A problem with CA-4 is that for it to be biologically active it needs to be in the cis conformation but is more stable in the trans conformation. Creating a β-lactam analogue of CA-4 is beneficial because the β-lactam replaces the ethylene bridge in CA-4 and makes the molecule more rigid, keeping it more aligned in the cis conformation. To synthesize the β-lactams, imines will first be synthesized, which will then be reacted with ketenes using a Staudinger [2+2] cycloaddition. The imines will be synthesized with 3,4,5-trimethoxybenzaldehyde and a variety of different anilines. The synthesis of an imine has already been conducted where 3,4,5-trimethoxybenzalehayde was reacted with aniline. The imine was synthesized with quantitative yield. Throughout the project, the substituent on the benzene ring of the aniline will be changed to see if different substituents affect the β-lactams ability to target and bind to tubulin. Specific ketenes will be synthesized from different acid chlorides, based on the desired substituents to be placed in the alpha position of the β-lactam ring.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

The Importance Of Arginine In The Rotary Mechanism Of F-Type ATP Synthase
The synthesis and hydrolysis of adenosine triphosphate (ATP), a biological energy carrier, as performed by F-type ATP synthases is an integral part to life. Structurally, much is known about the enzyme; especially with the recent advancement of high resolution cryo electron microscopy structures. Despite this information, the intricacies of the rotation mechanism occurring between subunits a and c are not fully understood. This rotation is ultimately responsible for utilizing the proton gradient across a membrane to synthesize ATP. Previous research identified specific residues of the c subunit of E. coli F-ATPase that may be necessary for function. The arginine at position 50 appears to be involved in key interactions due to either its steric bulk or its positive charge. This residue is essential to the functionality of the enzyme while running in the ATP hydrolysis direction. The chemical properties have been manipulated via mutagenesis and cysteine modification with methanethiosulfonate to determine which amino acid characteristics are necessary for function. Functionality is being tested using a hydrolysis based proton pumping assay as well as an ATP synthesis assay.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse