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Synthesis of fluorinated nucleosides
Nguyen, Van Hai ; Hocek, Michal (advisor) ; Baszczyňski, Ondřej (referee)
The key intermediate 6-amino-7-iodo-7-deazapurine 3'-deoxy-3'-fluororibonucleoside was synthesized using multistep sequence of several reactions, which started from the commercially available D-xylose and 6-chloro-7-deazapurine. The synthetic strategy was based on fluorination of sugar and glycosylation with corresponding nucleobase afterwards. The fluorination of 5-protected-1,2-isopropylidine xylose with different protecting groups at position 5 always led to elimination. It was later discovered that isopropylidine forces the conformation, which is unfavorable for substitution. During the extensive optimization it was also found out that DAST appears to be an optimal fluorinating agent. Fluorination was performed on 2,3-unprotected xylose, which was subsequently used for glycosylation. After several unsuccessful attempts on "protection group free" glycosylation, Vorbrüggen glycosylation was successful and gave desired 3'-fluoro nucleoside in good yield. However, benzoyl group had to be introduced into position 2'. The protected nucleoside was then aminated and simultaneously deproctected with solution of aqueous NH3 and 1,4-dioxane. The obtained key intermediate was used for synthesis of a small series of desired 6-amino-7-hetaryl nucleoside using Pd-catalyzed Suzuki reaction under aqueous...
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Study of adenosine effects on proliferation of BeWo cell line
Papírník, Josef ; Červený, Lukáš (advisor) ; Vokřál, Ivan (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Josef Papírník Supervisor: doc. PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: Studium of adenosine on proiferation activity in BeWo cell line The placenta is a rapidly developing organ that provides nutrition, protection and environment for the growing fetus. Fetal development is dependent on the supply of nutrients from the mother's blood either by passive diffusion or mediated by transporters. One of the essential nutrients are nucleosides, which are known to promote DNA synthesis and thus the growth of certain tissues. In order to pass across the plasma membrane they need nukleoside transporters (NTs) because of its hydrophilic feature. Additionally Ado takes part in cell signaling. Its wide- ranging effects, including influencing proliferation, are mediated by its binding to adenosine receptors (ARs). The placenta expresses NTs and ARs, which means that it is equipped to uptake nucleosides from maternal blood and has ability to receive signals from the external environment via the adenosine molecule. However, the importance of nucleosides for placental growth has not been investigated yet. The aim of this thesis is to test the effect of nucleosides on the proliferation of...
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Study of adenosine effects on proliferation of JEG-3 cell line
Nguyen, Ngoc Duong ; Červený, Lukáš (advisor) ; Jirkovský, Eduard (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Student: Nguyen Ngoc Duong Supervisor: doc. PharmDr. Lukáš Červený, Ph.D. Title of diploma thesis: Effect of adenosine on the proliferation of JEG-3 cell line Adenosine is a purinergic signaling molecule that is used in nucleic acid synthesis. Transport of hydrophilic nucleosides through the plasma and/or organelle membranes is provided by equilibrative nucleoside transporters (ENTs), members of the SLC29A transporter family, and concentrative nucleoside transporters (CNTs), members of the SLC28A transporter family. The placenta is a complex and rapidly growing organ. It shows some patterns similar to tumors except for the fact that the placenta's growth is fully controlled. It was found that extracellular nucleosides support the proliferation of cancerous and some non-cancerous cells. The placenta expresses high levels of NTs which indicates the placenta's ability to take up the nucleosides from circulation, however, the contribution of this process to placental growth is known. The diploma thesis aims to test the effect of adenosine and other nucleosides on trophoblast proliferation. We evaluated whether adenosine and other nucleosides increase the proliferation of the choriocarcinoma-derived JEG-3 cell...
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Modified ribonucleotides as building blocks for enzymatic construction of functionalized RNA or as antiviral compounds
Milisavljević, Nemanja ; Hocek, Michal (advisor) ; Baszczyňski, Ondřej (referee) ; Krečmerová, Marcela (referee)
The aim of this thesis was to study the steric influence of the base-modified nucleoside triphosphates (NTPs) on the enzymatic incorporation into RNA, as well as to study their inhibitory effect on different viral RNA polymerases in vitro. Their parent nucleosides and prodrug derivatives were also prepared and their antiviral activity evaluated. In the first part of the thesis, NTPs bearing groups varying in size from small methyl and ethynyl substituents via medium-size phenyl and benzofuryl groups, up to large dibenzofuran ring were prepared. Aromatic substituents were installed via Suzuki coupling on iodinated triphosphates or, in the case of modified guanosines, by the phosphorylation of modified nucleosides. Methyl and ethynyl NTPs were prepared via Pd-catalyzed coupling with AlMe3 and Sonogashira coupling, respectively, followed by the phosphorylation of modified nucleoside. To examine their incorporation into RNA by T7 RNA polymerase, templates coding for 35mer RNA containing one, three or seven modifications were designed. Modified pyrimidine triphosphates worked well for all the sequences, while the biggest dibenzofuryl group was not accepted in the difficult sequence with seven modifications. In the case of AR TPs dibenzofuryl modification did not incorporate at all, while other...
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Synthesis of fluorinated nucleosides
Nguyen, Van Hai ; Hocek, Michal (advisor) ; Baszczyňski, Ondřej (referee)
The key intermediate 6-amino-7-iodo-7-deazapurine 3'-deoxy-3'-fluororibonucleoside was synthesized using multistep sequence of several reactions, which started from the commercially available D-xylose and 6-chloro-7-deazapurine. The synthetic strategy was based on fluorination of sugar and glycosylation with corresponding nucleobase afterwards. The fluorination of 5-protected-1,2-isopropylidine xylose with different protecting groups at position 5 always led to elimination. It was later discovered that isopropylidine forces the conformation, which is unfavorable for substitution. During the extensive optimization it was also found out that DAST appears to be an optimal fluorinating agent. Fluorination was performed on 2,3-unprotected xylose, which was subsequently used for glycosylation. After several unsuccessful attempts on "protection group free" glycosylation, Vorbrüggen glycosylation was successful and gave desired 3'-fluoro nucleoside in good yield. However, benzoyl group had to be introduced into position 2'. The protected nucleoside was then aminated and simultaneously deproctected with solution of aqueous NH3 and 1,4-dioxane. The obtained key intermediate was used for synthesis of a small series of desired 6-amino-7-hetaryl nucleoside using Pd-catalyzed Suzuki reaction under aqueous...
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Development of new glycosylation methods for the synthesis of nucleosides
Downey, Alan Michael ; Hocek, Michal (advisor) ; Křen, Vladimír (referee) ; Kočovský, Pavel (referee)
As they make up DNA and RNA, nucleosides are considered the key to life. Synthetic nucleosides also constitute many drugs that treat viral infections and cancer. As a result, more efficient methods to access these crucial molecules would have implications that extend beyond a synthetic chemist's benchtop and into medicinal chemistry and medical research. One of the most challenging steps in the synthesis of nucleosides is the glycosylation step between the acceptor heterocycle (nucleobase) and the saccharide-based donor. Often to obtain satisfactory yield of this step with good regio- and stereochemical control the extensive use of protecting groups must be employed to squelch reactivity at unwanted reactive groups. Consequently, this process of protection−glycosylation−deprotection is laborious, inefficient, and often requires the use of toxic reagents. It would be, therefore, highly welcomed if new methodology to effect this glycosylation step was designed that reduces or removes the need to use protecting groups, but would still provide nucleosides in good yield, regio- and stereoselectively. Herein, this thesis presents my efforts into achieving this end. By employing modified Mitsunobu conditions, I determined that it is possible to directly glycosylate a nucleobase with D-ribose to afford...
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