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Florida International University
1.
Rayala, Ramanjaneyulu.
Design and Synthesis of Novel Nucleoside Analogues: Oxidative and Reductive Approaches toward Synthesis of 2'-Fluoro Pyrimidine Nucleosides.
Degree: PhD, Chemistry, 2015, Florida International University
URL: https://digitalcommons.fiu.edu/etd/2172 
;
10.25148/etd.FIDC000129
;
FIDC000129
► Fluorinated nucleosides, especially the analogues with fluorine atom(s) in the ribose ring, have been known to exert potent biological activities. The first part of…
(more)
▼ Fluorinated nucleosides, especially the analogues with fluorine atom(
s) in the ribose ring, have been known to exert potent biological activities. The first part of this dissertation was aimed at developing oxidative desulfurization-fluorination and reductive
desulfonylation-fluorination methodologies toward the synthesis of 2'-mono and/or 2',2'-difluoro pyrimidine nucleosides from the corresponding 2'-arylthiopyrimidine precursors. Novel
oxidative desulfurization-difluorination methodology was developed for the synthesis of α,α-difluorinted esters from the corresponding α-arylthio esters, wherein the arylthio group is present on a secondary internal carbon. For the reductive desulfonylation studies, cyclic voltammetry was utilized to measure the reduction potentials at which the sulfone moiety of substrates can be cleaved.
The 5-bromo pyrimidine nucleosides and 8-bromo purine nucleosides act as crucial intermediates in various synthetic transformations. The second part of the present dissertation was designed to develop a novel bromination methodology using 1,3-dibromo-5,5-dimethylhydantoin (DBH). Various protected and deprotected pyrimidine and purine nucleosides were converted to their respective C5 and C8 brominated counterparts using DBH. The effect of Lewis acids, solvents, and temperature on the efficiency of bromination was studied. Also,
N-bromosuccinimide (NBS) or DBH offered a convenient access to 8-bromotoyocamycin and 8-bromosangivamycin.
Third part of this research work focuses on the design and synthesis of 6-
N-benzylated derivatives of 7-deazapurine nucleoside antibiotics, such as tubercidin, sangivamycin and toyocamycin. Target molecules were synthesized by two methods. First method involves treatment of 7-deazapurine substrates with benzylbromide followed by dimethylamine-promoted Dimroth rearrangement. The second method employs fluoro-diazotization followed by
SNAr displacement of the 6-fluoro group by a benzylamine. The 6-
N-benzylated 7-deazapurine nucleosides showed type-specific inhibition of cancer cell proliferation at micromolar concentrations and weak inhibition of human equilibrative nucleoside transport protein (hENT1).
In the fourth part of this dissertation, syntheses of C7 or C8 modified 7-deazapurine nucleosides, which might exhibit fluorescent properties, were undertaken. 8-Azidotoyocamycin was synthesized by treatment of 8-bromotoyocamycin with sodium azide. Strain promoted click chemistry of 8-azidotoyocamycin with cyclooctynes gave the corresponding 8-triazolyl derivatives. Alternatively, 7-benzotriazolyl tubercidin was synthesized by iodine catalyzed CH arylation of tubercidin with benzotriazole.
Advisors/Committee Members: Stanislaw F. Wnuk, Kathleen S. Rein, David A. Becker, Anthony P. DeCaprio, Salvatore D. Lepore.
Subjects/Keywords: Fluorination; Desulfurization; Desulfonylation; Pyrimidines; Purines; 7-Deazapurines; DBH; Click Chemistry; C-H Functionalization; One Electron Oxidation; Carbohydrates; Heterocyclic Compounds; Nucleic Acids, Nucleotides, and Nucleosides
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APA (6th Edition):
Rayala, R. (2015). Design and Synthesis of Novel Nucleoside Analogues: Oxidative and Reductive Approaches toward Synthesis of 2'-Fluoro Pyrimidine Nucleosides. (Doctoral Dissertation). Florida International University. Retrieved from https://digitalcommons.fiu.edu/etd/2172 ; 10.25148/etd.FIDC000129 ; FIDC000129
Chicago Manual of Style (16th Edition):
Rayala, Ramanjaneyulu. “Design and Synthesis of Novel Nucleoside Analogues: Oxidative and Reductive Approaches toward Synthesis of 2'-Fluoro Pyrimidine Nucleosides.” 2015. Doctoral Dissertation, Florida International University. Accessed March 05, 2021.
https://digitalcommons.fiu.edu/etd/2172 ; 10.25148/etd.FIDC000129 ; FIDC000129.
MLA Handbook (7th Edition):
Rayala, Ramanjaneyulu. “Design and Synthesis of Novel Nucleoside Analogues: Oxidative and Reductive Approaches toward Synthesis of 2'-Fluoro Pyrimidine Nucleosides.” 2015. Web. 05 Mar 2021.
Vancouver:
Rayala R. Design and Synthesis of Novel Nucleoside Analogues: Oxidative and Reductive Approaches toward Synthesis of 2'-Fluoro Pyrimidine Nucleosides. [Internet] [Doctoral dissertation]. Florida International University; 2015. [cited 2021 Mar 05].
Available from: https://digitalcommons.fiu.edu/etd/2172 ; 10.25148/etd.FIDC000129 ; FIDC000129.
Council of Science Editors:
Rayala R. Design and Synthesis of Novel Nucleoside Analogues: Oxidative and Reductive Approaches toward Synthesis of 2'-Fluoro Pyrimidine Nucleosides. [Doctoral Dissertation]. Florida International University; 2015. Available from: https://digitalcommons.fiu.edu/etd/2172 ; 10.25148/etd.FIDC000129 ; FIDC000129
2.
sun, pengfei.
Characterization of an Epoxide Hydrolase from the Florida Red Tide Dinoflagellate, Karenia brevis.
Degree: PhD, Chemistry, 2015, Florida International University
URL: https://digitalcommons.fiu.edu/etd/2066
;
10.25148/etd.FIDC000133
;
FIDC000133
► Polyether compounds are a subgroup of natural products with regular occurrence of multiple C-O-C motifs. The biosynthetic origin of polycylic polethers has been studied…
(more)
▼ Polyether compounds are a subgroup of natural products with regular occurrence of multiple C-O-C motifs. The biosynthetic origin of polycylic polethers has been studied and the majority of them are derived from polyketide or terpene pathways. Normally, the polycyclic polyethers can be divided into two groups based on their structural features: the first group features multiple rings that are interconnected by carbon-carbon single bond, which are produced by a biosynthetic cascade of
exo epoxide-opening reactions; the other group has multiple fused cyclic ethers and are formed by an cascade of
endo epoxide-opening reactions.
Karenia brevis (
K. brevis) is known as principle harmful bloom (HAB) organism of the Gulf of Mexico which can cause red tides. Brevetoxins (PbTx) are a suit of cyclic polyether ladder compounds produced by
K. brevis. Brevetoxins are neurotoxins that can bind to voltage-gated sodium channels in nerve and muscle cells, resulting in disruption of normal neurological processes causing the human illness which is clinically described as neurotoxic shellfish poisoning (NSP).
Inspired by Cane-Celmer-Wesley’
s proposal regarding monensin biosynthesis, Nakanishi and Shimizu proposed a biosynthetic pathway for brevetoxin which suggests that PKS-mediated synthesis of the polyene is followed by epoxidation to afford a polyepoxide which then undergoes an epoxide-opening cascade, catalyzed by an epoxide hydrolase (EH).
To find evidence to support the hypothesis that an epoxide hydrolase from polyether ladder producing dinoflagellates will catalyze the construction of the polyether ladder framework from polyepoxide substrates, and to study the role of epoxide hydrolase in the biosynthesis of polyether ladder compounds, it is necessary to identify and produce one or more epoxide hydrolase from dinoflagellates. The methods to detect epoxide hydrolase activity in
K. brevis and different techniques to obtain epoxide hydrolases from
K. brevis are discussed. A microsomal EH identified from a
K. brevis EST library was cloned and expressed. The characterization of this EH, including substrate selectivity and enantioselectivity as well as its potential to catalyze the critical
ento-tet cyclization epoxy alcohol, is discussed.
Advisors/Committee Members: Kathleen S. Rein, David Becker, Watson Lees, Lidia Kos, Xiaotang Wang.
Subjects/Keywords: Karenia brevis; dinoflagellate; brevetoxin; epoxide hydrolase; Biochemistry; Molecular Biology
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APA (6th Edition):
sun, p. (2015). Characterization of an Epoxide Hydrolase from the Florida Red Tide Dinoflagellate, Karenia brevis. (Doctoral Dissertation). Florida International University. Retrieved from https://digitalcommons.fiu.edu/etd/2066 ; 10.25148/etd.FIDC000133 ; FIDC000133
Chicago Manual of Style (16th Edition):
sun, pengfei. “Characterization of an Epoxide Hydrolase from the Florida Red Tide Dinoflagellate, Karenia brevis.” 2015. Doctoral Dissertation, Florida International University. Accessed March 05, 2021.
https://digitalcommons.fiu.edu/etd/2066 ; 10.25148/etd.FIDC000133 ; FIDC000133.
MLA Handbook (7th Edition):
sun, pengfei. “Characterization of an Epoxide Hydrolase from the Florida Red Tide Dinoflagellate, Karenia brevis.” 2015. Web. 05 Mar 2021.
Vancouver:
sun p. Characterization of an Epoxide Hydrolase from the Florida Red Tide Dinoflagellate, Karenia brevis. [Internet] [Doctoral dissertation]. Florida International University; 2015. [cited 2021 Mar 05].
Available from: https://digitalcommons.fiu.edu/etd/2066 ; 10.25148/etd.FIDC000133 ; FIDC000133.
Council of Science Editors:
sun p. Characterization of an Epoxide Hydrolase from the Florida Red Tide Dinoflagellate, Karenia brevis. [Doctoral Dissertation]. Florida International University; 2015. Available from: https://digitalcommons.fiu.edu/etd/2066 ; 10.25148/etd.FIDC000133 ; FIDC000133
3.
Wang, Wentian.
Asymmetric Syntheses of Analogs of Kainic Acid.
Degree: PhD, Chemistry, 2012, Florida International University
URL: https://digitalcommons.fiu.edu/etd/756
;
10.25148/etd.FI12113007
;
FI12113007
► Kainic acid has been used for nearly 50 years as a tool in neuroscience due to its pronounced neuroexcitatory properties. However, the significant price…
(more)
▼ Kainic acid has been used for nearly 50 years as a tool in neuroscience due to its pronounced neuroexcitatory properties. However, the significant price increase of kainic acid resulting from the disruption in the supply from its natural source, the alga
Digenea Simplex, as well as inefficient synthesis of kainic acid, call for the exploration of functional mimics of kainic acid that can be synthesized in a simpler way.
Aza kainoids analog could be one of them. The unsubstituted aza analog of kainoids has demonstrates its ability as an ionotropic glutamate receptor agonist and showed affinity in the chloride dependent glutamate (GluCl) binding site. This opened a question of the importance of the presence of one nitrogen or both nitrogens in the aza kainoid analogs for binding to glutamate receptors. Therefore, two different pyrrolidine analogs of kainic acid,
trans-4-(carboxymethyl)pyrrolidine-3-carboxylic acid and
trans-2-carboxy-3-pyrrolidineacetic acid, were synthesized through multi-step sequences. The lack of the affinity of both pyrrolidine analogs in GluCl binding site indicated that both nitrogens in aza kainoid analogs are involved in hydrogen bonding with receptors, significantly enhancing their affinity in GluCl binding site.
Another potential functional mimic of kainic acid is isoxazolidine analogs of kainoids whose skeleton can be constituted directly via a 1, 3 dipolar cycloaddition as the key step. The difficulty in synthesizing N-unsubstituted isoxazolidines when applying such common protecting groups as alkyl, phenyl and benzyl groups, and the requirement of a desired enantioselectivity due to the three chiral ceneters in kainic acid, pose great challenges. Hence, several different protected nitrones were studied to establish that diphenylmethine nitrone may be a good candidate as the dipole in that the generated isoxazolidines can be deprotected in mild conditions with high yields. Our investigations also indicated that the exo/endo selectivity of the 1, 3 dipolar cycloaddition can be controlled by Lewis acids, and that the application of a directing group in dipolarophiles can accomplish a satisfied enantioselectivity. Those results demonstrated the synthesis of isoxazoldines analogs of kainic acid is very promising.
Advisors/Committee Members: Kathleen S. Rein, David Becker, Kevin O'Shea, Philip Stoddard, Waston Lees.
Subjects/Keywords: Kainic Acid; Pyrrolidine; Dipolar cycloaddition; Asymmetric; Exo/Endo; Isoxazolidine; Mosher method
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APA (6th Edition):
Wang, W. (2012). Asymmetric Syntheses of Analogs of Kainic Acid. (Doctoral Dissertation). Florida International University. Retrieved from https://digitalcommons.fiu.edu/etd/756 ; 10.25148/etd.FI12113007 ; FI12113007
Chicago Manual of Style (16th Edition):
Wang, Wentian. “Asymmetric Syntheses of Analogs of Kainic Acid.” 2012. Doctoral Dissertation, Florida International University. Accessed March 05, 2021.
https://digitalcommons.fiu.edu/etd/756 ; 10.25148/etd.FI12113007 ; FI12113007.
MLA Handbook (7th Edition):
Wang, Wentian. “Asymmetric Syntheses of Analogs of Kainic Acid.” 2012. Web. 05 Mar 2021.
Vancouver:
Wang W. Asymmetric Syntheses of Analogs of Kainic Acid. [Internet] [Doctoral dissertation]. Florida International University; 2012. [cited 2021 Mar 05].
Available from: https://digitalcommons.fiu.edu/etd/756 ; 10.25148/etd.FI12113007 ; FI12113007.
Council of Science Editors:
Wang W. Asymmetric Syntheses of Analogs of Kainic Acid. [Doctoral Dissertation]. Florida International University; 2012. Available from: https://digitalcommons.fiu.edu/etd/756 ; 10.25148/etd.FI12113007 ; FI12113007
Florida International University
4.
Liu, Li.
Absolute Configuration and Biosynthesis of Pahayokolide A from Lyngbya sp. Strain 15-2 of the Florida Everglades.
Degree: Chemistry, 2009, Florida International University
URL: https://digitalcommons.fiu.edu/etd/134
;
10.25148/etd.FI09120808
;
FI09120808
► Pahayokolides A-D are cytotoxic cyclic polypeptides produced by the freshwater cyanobacterium Lyngbya sp. strain 15-2 that possess an unusual β-amino acid, 3-amino-2,5,7,8-tetrahydroxy-10-methylundecanoic acid (Athmu).…
(more)
▼ Pahayokolides A-D are cytotoxic cyclic polypeptides produced by the freshwater cyanobacterium Lyngbya sp. strain 15-2 that possess an unusual β-amino acid, 3-amino-2,5,7,8-tetrahydroxy-10-methylundecanoic acid (Athmu). The absolute configuration of pahayokolides A-D was determined using advanced Marfey’
s method. It was also confirmed that a pendant N-acetyl-N-methyl leucine moiety in pahayokolide A was absent in pahayokolides B and pahayokolides C-D were conformers of pahayokolide A. Feeding experiments indicated that the biosynthesis of the Athmu sidechain arises from leucine or α-ketoisovalerate, however could not be further extended by three rounds of condensation with malonate units. Putative four peptide and one unique polyketide synthetases in Lyngbya sp. strain 15-2 were identified by using a PCR method and degenerate primers derived from conserved core sequences of known NRPSs and PKSs. Identification of one unique KS domain conflicted with the logic rule that the long side chain of Athmu was assembled by three rounds of ketide extensions if PKSs were involved. A gene cluster (pah) encoding a peptide synthetase putatively producing pahayokolide was cloned, partially sequenced and characterized. Seven modules of the non-ribosomal peptide synthetase (NRPS) were identified. Ten additional opening reading frames (ORFs) were found, responsible for peptide resistance, transport and degradation. Although the predicted substrate specificities of NRPS agreed with the structure of pahayokolide A partially, the disagreement could be explained. However, no PKS gene was found in the pah gene cluster.
Advisors/Committee Members: Kathleen S. Rein, José Almirall, Watson Lees, Fenfei Leng, David W. Lee.
Subjects/Keywords: Lyngbya; Peptide; Pahayokolide A; Absolute configuration; Biosynthesis; NRPS; Stable isotope incprporation; Analytical Chemistry; Biochemistry; Medicinal-Pharmaceutical Chemistry
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APA ·
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MLA ·
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CSE |
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Manager
APA (6th Edition):
Liu, L. (2009). Absolute Configuration and Biosynthesis of Pahayokolide A from Lyngbya sp. Strain 15-2 of the Florida Everglades. (Thesis). Florida International University. Retrieved from https://digitalcommons.fiu.edu/etd/134 ; 10.25148/etd.FI09120808 ; FI09120808
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Liu, Li. “Absolute Configuration and Biosynthesis of Pahayokolide A from Lyngbya sp. Strain 15-2 of the Florida Everglades.” 2009. Thesis, Florida International University. Accessed March 05, 2021.
https://digitalcommons.fiu.edu/etd/134 ; 10.25148/etd.FI09120808 ; FI09120808.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Liu, Li. “Absolute Configuration and Biosynthesis of Pahayokolide A from Lyngbya sp. Strain 15-2 of the Florida Everglades.” 2009. Web. 05 Mar 2021.
Vancouver:
Liu L. Absolute Configuration and Biosynthesis of Pahayokolide A from Lyngbya sp. Strain 15-2 of the Florida Everglades. [Internet] [Thesis]. Florida International University; 2009. [cited 2021 Mar 05].
Available from: https://digitalcommons.fiu.edu/etd/134 ; 10.25148/etd.FI09120808 ; FI09120808.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Liu L. Absolute Configuration and Biosynthesis of Pahayokolide A from Lyngbya sp. Strain 15-2 of the Florida Everglades. [Thesis]. Florida International University; 2009. Available from: https://digitalcommons.fiu.edu/etd/134 ; 10.25148/etd.FI09120808 ; FI09120808
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Florida International University
5.
Di, Mingping.
Syntheses of aza analogs of kainoids.
Degree: PhD, Chemistry, 2006, Florida International University
URL: https://digitalcommons.fiu.edu/etd/2795
;
10.25148/etd.FI14062265
;
FI14062265
► The kainoids are a class of non-proteinogenic pyrrolidine dicarboxylates that exhibit both excitatory and excitotoxic activities. These activities are a result of the ability…
(more)
▼ The kainoids are a class of non-proteinogenic pyrrolidine dicarboxylates that exhibit both excitatory and excitotoxic activities. These activities are a result of the ability of the kainoids to act as glutamate receptor agonists by activating ionotropic glutamate receptors. The parent of this group of compounds is x-kainic acid. Kainic acid is isolated from the seaweed
Diginea simplex and has been used in Asian countries as a treatment for intestinal worms in children. In addition it is used extensively by neuropharmacologists for the study of glutamate receptors. Several years ago, the world'
s sole supplier of kainic acid discontinued this product. Since that time, other sources have appeared, however, the price of kainic acid remains significantly higher than it once was. We have thus been working on synthesizing aza analogs of kainoids which would be less costly but potentially potent alternatives to kainic acid via the dipolar cycloadditions of diazoalkanes with
trans diethyl glutaconate. These 1, 3-dipolar cycloadditions yielded 2- pyrazolines or pyrazoles. The 2-pyrazolines may be precursors to aza analogs of kainoids. The regioselectivity of these 1, 3-dipolar cycloadditions and isomerization of the 1- pyrazolines to 2-pyrazolines was evaluated. Reductions of the 2-pyrazolines yielded aza analogs of kainoids.
Advisors/Committee Members: Kathleen S. Rein, Stanislaw Wnuk, Philip Stoddard, Fenfei Leng, John T. Landrum.
Subjects/Keywords: Chemistry
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APA ·
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Manager
APA (6th Edition):
Di, M. (2006). Syntheses of aza analogs of kainoids. (Doctoral Dissertation). Florida International University. Retrieved from https://digitalcommons.fiu.edu/etd/2795 ; 10.25148/etd.FI14062265 ; FI14062265
Chicago Manual of Style (16th Edition):
Di, Mingping. “Syntheses of aza analogs of kainoids.” 2006. Doctoral Dissertation, Florida International University. Accessed March 05, 2021.
https://digitalcommons.fiu.edu/etd/2795 ; 10.25148/etd.FI14062265 ; FI14062265.
MLA Handbook (7th Edition):
Di, Mingping. “Syntheses of aza analogs of kainoids.” 2006. Web. 05 Mar 2021.
Vancouver:
Di M. Syntheses of aza analogs of kainoids. [Internet] [Doctoral dissertation]. Florida International University; 2006. [cited 2021 Mar 05].
Available from: https://digitalcommons.fiu.edu/etd/2795 ; 10.25148/etd.FI14062265 ; FI14062265.
Council of Science Editors:
Di M. Syntheses of aza analogs of kainoids. [Doctoral Dissertation]. Florida International University; 2006. Available from: https://digitalcommons.fiu.edu/etd/2795 ; 10.25148/etd.FI14062265 ; FI14062265
. 
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