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School of Chemistry and Biochemistry

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College of Sciences

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The evaluation of novel anti-inflammatory compounds in cell culture and experimental arthritis and identification of an inhibitor to early-stage loblolly pine somatic embryo growth

(Georgia Institute of Technology, 2013-11-19) Lucrezi, Jacob

The interactions between the immune and nervous systems play an important role in immune and inflammatory conditions. Substance P (SP), the unidecapeptide RPKPQQFFGLM-NH2, is known to upregulate the production of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α. We report here that 5 (Acetylamino) 4 oxo-6-phenyl-2-hexenoic acid methyl ester (AOPHA-Me) and 4 phenyl 3 butenoic acid (PBA), two anti-inflammatory compounds developed in our laboratory, reduce SP stimulated TNF-α expression in RAW 264.7 macrophages. We also show that AOPHA Me and PBA both inhibit SP stimulated phosphorylation of JNK and p38 MAPK. Furthermore, molecular modeling studies indicate that both AOPHA Me and PBA dock at the ATP binding site of apoptosis signal regulating kinase 1 (ASK1) with predicted docking energies of -7.0 kcal/mol and 5.9 kcal/mol, respectively; this binding overlaps with that of staurosporine, a known inhibitor of ASK1. Taken together, these findings support the conclusion that AOPHA Me and PBA inhibition of TNF-α expression in SP-stimulated RAW 264.7 macrophages is a consequence of the inhibition JNK and p38 MAPK phosphorylation. We have previously shown that AOPHA-Me and PBA inhibit the amidative bioactivation of SP, which also would be expected to decrease formation of pro-inflammatory cytokines. It is conceivable that this dual action of inhibiting amidation and MAPK phosphorylation may be of some advantage in enhancing the anti-inflammatory activity of a therapeutic molecule. We also encapsulated AOPHA-Me separately in polyketal and poly(lactic co glycolic acid) microparticles. The in-vitro release profiles of AOPHA-Me from these particles were characterized. We have also shown that AOPHA-Me, when encapsulated in PCADK microparticles, is an effective treatment for edema induced by adjuvant arthritis in rats. In separate work, it was determined that myo inositol 1,2,3,4,5,6 hexakisphosphate is an inhibitor to early-stage Loblolly pine somatic embryo growth. In addition, it was determined that muco inositol 1,2,3,4,5,6 hexakisphosphate is not an inhibitor to early-stage Loblolly pine somatic embryo growth. These experiments demonstrate the stereochemical dependence of myo inositol 1,2,3,4,5,6 hexakisphosphates inhibitory activity.
An investigation of the therapeutic potential of phenylaminoalkyl selenides through mechanistic and biological studies and an exploration of ciber: the center of innovative biomaterial education and research

(Georgia Institute of Technology, 2011-11-16) Cowan, Elizabeth Alice

The overproduction of reactive oxygen species (ROS) have been linked to diseases and other pathologies. As therapeutic agents, antioxidants have been tested and some shown to attenuate these diseases by relieving oxidative stress. The May laboratory has previously developed a family of phenylaminoalkyl selenides and has demonstrated the antihypertensive and antioxidant properties of these compounds. To further understand the antioxidant property of these selenide compounds, the two step mechanism of the reaction between the selenoxide form and glutathione was investigated by stopped-flow and mass spectrometry, leading to the detection and characterization of a novel thioselenurane intermediate. Mass spectrometry studies supported the redox cycle of the selenide compounds as a straightforward cycle with no byproducts or side reactions and was the first evidence reported of a thioselenurane intermediate present in a reduction reaction of a selenoxide. The therapeutic potential of these compounds was further supported by cell and histological studies demonstrating their ability to alleviate the cardiotoxic effect of anthracyclines without affecting the anti-cancer property of the drugs. Codosage of a phenylaminoethyl selenide with Doxorubicin decreased the infiltration of inflammation cells in the myocardium of mice. Phenylaminoethyl selenides were also able to maintain the body weight of mice treated with Doxorubicin, compared to mice treated with Doxorubicin alone. In order to make the possibility of using Phenylaminoalkyl selenides as therapeutic agents or supplements with other agents, delivery of the compounds was investigated. N acetyl phenylaminoethyl selenides were successfully encapsulated into poly(lactic-co-glycolic) (PLGA) nanoparticles using the nanoprecipitation technique. An attempt was made to demonstrate the ability of these selenide- nanoparticles to reduce cellular oxidative stress caused by incubation with LPS. Future studies are needed to optimize the loading of the selenide compounds into nanocarriers and to demonstrate the ability of the encapsulated drug to work as the free drug. The long term goal of this research is to fully understand the potential of phenylaminoalkyl selenides as an efficient therapeutic agent for ailments derived from increased levels of ROS and a state of oxidative stress. As a supplemental project funded by the National Science Foundation, the Center for Innovative Biomaterial Education and Research (CIBER) was created. Enzymatically catalyzed reaction and polymerizations were investigated using Candida antarctica Lipase B (CALB). Several CALB catalyzed Michael addition reactions were successful and yielded compounds that could be used as future reactants and monomers. As an education requirement of the project a website was created in order to educate the public of the importance, sources and uses of biomaterials. The website provides information for all levels of students and educators. This center has allowed The Georgia Institute of Technology to form relationships and exchange programs with leading universities around the world allowing the exchange of knowledge and research in biomaterials.
Design, synthesis, kinetic analysis, molecular modeling, and pharmacological evaluation of novel inhibitors of peptide amidation

(Georgia Institute of Technology, 2008-11-18) Foster, Michael Scott

Novel, rationally-designed acrylate analogs of various known dipeptide substrates were found to be mechanism-based inactivators of the enzyme peptidylglycine alpha-amidating monooxygenase (PAM, EC 1.14.17.3). This enzyme is responsible for the rate-limiting and final bioactivation step, a C-terminal amidation of glycine-extended peptides, of a variety of peptide hormones including the potent pro-inflammatory compound Substance P. Protein-ligand docking studies, in tandem with in vitro kinetic analysis of these inactivators, indicated that the rational design of this class of compounds was successful in creating potent competitive inactivators of this enzyme. Pharmacological evaluation, via both acute and chronic models of inflammation in Sprague-Dawley rats, of these compounds indicates that they are highly potent anti-inflammatory agents which ameliorate both acute carrageenan-induced edema and the deleterious effects of chronic adjuvant-induced polyarthritis. Furthermore, these compounds were also able to induce a return toward a more normal phenotype in cancerous WB-Ras epithelial cells, via the interruption of the growth factor-stimulated pathway precipitated by Substance P. Finally, our modeling studies provide a structural basis for both the reaction and subsite stereospecificity of PAM toward its substrates, competitive inhibitors, and mechanism-based inactivators.
Discovery and characterization of a signaling molecule regulating somatic embryogenesis in loblolly pine

(Georgia Institute of Technology, 2008-03-04) Wu, Di

myo-Inositol-1,2,3,4,5,6-hexakisphosphate (InsP6), also called phytic acid, is ubiquitous in eukaryotic cells and the most abundant inositol phosphate derivative. Loblolly pine (LP, Pinus taeda) constitutes the primary commercial species in the southern forest of U.S. Somatic embryogenesis (SE) is an effective technique to maintain the desirable genetic composition of the progeny and to accomplish the efficiency of propagation. SE can also serve as a tool for study of plant development. Unlike angiosperm embryos with attached cotyledons as seed storage organs, the diploid conifer embryo is surrounded by the unattached haploid female gametophyte (FG). In LP SE, FG tissue is absent in the embryogenic tissue culture. We found that extracts from early-stage FG stimulate growth and multiplication of early-stage somatic embryos, whereas FG water extracts from late stage contain substance(s) inhibitory to early-stage somatic embryo growth (DeSilva et al., 2007). We now present the isolation and identification of the inhibitory substance as InsP6 by means of water extraction, two gel filtrations and two ion exchange FPLC chromatographies. The results represent the first complete structural characterization of InsP6 from a natural product using LC/MS, LC/MS/MS, exact MS, 1D- and 2D-NMR analyses. We also report that there is a good correlation between the amount of InsP6 purified from FG tissue (1.3 nmoles per full-term FG) and the amount of InsP6 which inhibits somatic embryo growth. This novel approach of isolating and characterizing InsP6 from plant tissue, and investigating its role on SE can allow us to improve SE technology by circumventing current bottleneck, to elucidate enigmatic functions of InsP6 in plants, and most importantly, to utilize this molecule properly.
Selenium redox cycling; isolation and characterization of a stimulatory component from tissue of loblolly pine for multiplication of somatic embryos; development of an assay to measure l-phenylalanine concentration in blood plasma

(Georgia Institute of Technology, 2007-06-25) DeSilva, Veronica

Exogenously supplied organoselenium compounds, capable of propagating a selenium redox cycle, were shown to supplement natural cellular defenses against oxidants generated during biological activity. Phenylaminoalkyl selenides were developed in our laboratory as novel substrate analogs for the enzyme dopamine beta-monooxygenase. Recently, phenylaminoalkyl selenides were found to protect plasmid DNA and Molecular beacons from oxoperoxynitrate – mediated damage by scavenging this oxidant and forming the corresponding selenoxides as the sole selenium – containing products. Rate constants were determined for the reactions of the phenylaminoalkyl selenoxides with GSH at physiological pH and 25 degrees C. The kinetic data obtained in current and previous research was subsequently used in a MatLab simulation, which showed the feasibility of selenium redox cycling by GSH in the presence of a cellular oxidant, oxoperoxynitrate. Loblolly pine (LP, Pinus taeda) is the primary commercial species in southern forests covering 11.7 million hectares. Somatic embryogenesis (SE) is an effective technique to implement production of high value genotypes of LP. SE is a multi-step process, which includes initiation of somatic embryo (SME) growth from tree tissue, maintenance and multiplication of early stage SMEs and the maturation / germination phase. In this work, we isolated a substance from stage 2 or 3 LP female gametophyte (FG) tissue that stimulates early stage SME growth, and characterized this substance as citric acid on the basis of 1H NMR and mass spectrometry. We then demonstrated that topical application of citric acid to SMEs stimulates embryo colony growth at p = 0.05 for 3 of the 5 genotypes tested. Phenylketonuria (PKU) is an autosomal recessive disorder caused by an impaired conversion of L-phenylalanine (L-Phe) to L-tyrosine (L-Tyr). A novel assay based on enzymatic - colorimetric methodology (ECA) was developed in order to detect elevated concentrations of L-Phe in undeproteinized plasma of PKU patients via continuous spectrophotometric detection. We report here that L-Phe concentrations in undeproteinized plasma measured using our ECA were comparable to those determined on an amino acid analyzer based on Pearson correlation coefficients and a Bland and Altman comparison.
An exploration of biochemistry including biotechnology, structural characterization, drug design, and chromatographic analyses

(Georgia Institute of Technology, 2006-09-28) Burns, Kristi Lee

We now report an in depth analysis of the successful in vitro enzymatic synthesis of PHB utilizing the three-enzyme system from the bacteria Cupriavidus necator. Using HPLC methodology developed in this laboratory, and by adding each enzyme in a step-wise manner, we follow each individual stage in the three-enzyme route for PHB synthesis and delineate all stoichiometric relationships. We report the construction of the first metabolic model developed specifically for analyzing in vitro enzymatic PHB synthesis. We developed a hands-on student laboratory for culturing, producing, isolating, and purifying the bacterial biopolyesters PHB. We now report the first structural characterizations of iso-CoA, acetyl-iso-CoA, acetoacetyl-iso-CoA, and beta-hydroxybutyryl-iso-CoA using MS, MS/MS, and homo- and hetero-nuclear NMR analyses.We describe HPLC methodology to separate the isomers of several iso-CoA-containing compounds and report the first examples of iso-CoA-containing compounds acting as substrates in enzymatic acyl-transfer reactions. We describe a simple regioselective synthesis of iso-CoA from CoA. We also demonstrate a plausible mechanism, which accounts for the existence of iso-CoA isomers in commercial preparations of CoA-containing compounds. Herein we report that phenylaminoethyl selenide compounds protect DNA from peroxynitrite-mediated single-strand breaks. The mechanism of protection against peroxynitrite mediated DNA damage was investigated by HPLC. The chemistry of the reaction between peroxynitrite and HOMePAES was investigated using HPLC and HPLC/MS. The unique chemistry of the reaction between peroxynitrite and HOMePAES was investigated using HPLC and HPLC/MS. We report the development of novel CDB derivatives, which are selective COX-II inhibitors. A series of compounds were assayed with an in vitro colorimetric inhibitor screening and with a whole blood ELISA screening and the results indicate that MST is a selective inhibitor of COX-II.
Pharmacological evaluation of in vivo inhibitors of peptide amidation : 2 Biological synthesis of poly(3-hydroxybutyrate)

(Georgia Institute of Technology, 2002-05) Thompson, Jeremy
Molecular cloning and characterization of a novel developmental gene from loblolly pine - a new plant regulatory system

(Georgia Institute of Technology, 2001-08) Tulsyan, Anurag S.
The protective role of phenylaminoalkyl selenides against peroxynitrite-mediated reactions

(Georgia Institute of Technology, 2001-08) De Silva, Veronica
Hemodynamic effects of novel selenium antihypertensive agents : 2 Biocatalysis in organic and mixed solvents ; 3 Biotechnological production of polyesters

(Georgia Institute of Technology, 2001-05) Overcast, Jennifer Dawn