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I.Synthesis of acyclic nucleoside phosphonates with a thiadiazole base mimicking 5-azacytosine as compounds with potential biological activitiesII.Development of small molecules targeting c-MYC oncogene.
Pomeislová, Alice ; Krečmerová, Marcela (advisor) ; Jindřich, Jindřich (referee) ; Voltrová, Svatava (referee)
The first part of the thesis regards synthesis of N-[2-(phosphonomethoxy)ethyl] (PME) and (S)-3-hydroxy-2-(phosphonomethoxy)propyl ((S)-HPMP) derived acyclic nucleoside phosphonate (ANP) analogues carrying 5-amino-1,2,4-thiadiazol-3(2H)-one as a nucleobase that is supposed to mimic cytosine or 5-azacytosine. A series of 1,2,4-thiadiazole derivatives bearing at the N2 position PME- or (S)-HPMP-moiety and NH2-protecting group (benzoyl, ethoxycarbonyl, or Fmoc) were obtained as chemically stable ANP congeners. Their synthesis was performed via stepwise construction of the thiadiazole ring and required the use of two newly prepared synthons, PME-amine and (S)-HPMP-amine. However, all attempts to prepare the intended PME- and (S)-HPMP-thiadiazole phosphonic acids with free amino moiety failed due to instability of the N2 -substituted thiadiazole ring. Biological evaluation of twenty-one selected thiadiazole compounds towards two human cysteine- dependent enzymes, cathepsin K and glycogen synthase kinase 3ß, revealed that several compounds inhibited both enzymes in the low micromolar range. Some of these efficient inhibitors had also favourable toxicity profile at 100 µM, which makes them appropriate for further development of potential drug candidates. In the second part of the dissertation, design and...
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Synthesis of novel types of acyclic nucleoside phosphonates and preparation of prodrugs and drug delivery systems
Kalčic, Filip ; Janeba, Zlatko (advisor) ; Míšek, Jiří (referee) ; Krečmerová, Marcela (referee)
First part of this thesis was focused on the previously overlooked field of C1'-branched acyclic nucleoside phosphonates (ANPs). Five diverse synthetic approaches were developed/optimized affording key 6-chloropurine intermediates bearing N9 -phosphonomethoxyethyl (PME) branched at C1' position in 2-4 steps. It was demonstrated that these intermediates can be further vastly diversified into ANPs bearing both natural and unnatural nucleobases. Single enantiomers as well as racemates of final C1'-branched ANPs (overall 48 final compounds) were prepared and selected compounds were evaluated with respect to their biological properties. The aforementioned ANPs showed no antiviral potency against studied viruses and only weak to moderate cytostatic activity. Adenine C1'-branched ANPs proved to be the most potent currently known inhibitors of Trypanosoma brucei adenine phosphoribosyl transferase (TbrAPRT), an enzyme involved in purine salvage pathway (PSP) of T. brucei. Further biological evaluation of prepared compounds is in progress. Second part of this thesis was focused on development of novel prodrug moieties with higher selectivity index (i.e. toxicity/potency ratio - SI) based on so-called ProTide prodrugs where phenol (present in ProTides) was replaced by tyrosine derivatives. Tenofovir was...
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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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The synthesis of stable O-acetyl-adenosine diphosphoribose analogs and inhibitors of sirtuins
Dvořáková, Marcela ; Vaněk, Tomáš (advisor) ; Jindřich, Jindřich (referee) ; Krečmerová, Marcela (referee)
Acetylated adenosine diphosphoribose (OAADPR) is a product of protein deacetylation catalysed by class III of histone deacetylases called sirtuins. Sirtuins deacetylate histones and other proteins by unique mechanism coupled with consumption of stoichiometric amount of NAD+ . Sirtuins and OAADPR are implicated in the regulation of gene transcription, signalling and metabolic pathways and lifespan extension, thus preventing the development of age-related diseases. Even though, sirtuins are well studied, the exact biological role of OAADPR remains mainly unknown. Its further exploration is restricted by OAADPR's proneness to enzymatic hydrolysis. Therefore, non-hydrolysable analogues of OAADPR are needed to establish its biological function. These analogues are also expected to be competitive inhibitors of sirtuins, which may reveal their potential as therapeutic agents. A series of OAADPR analogues in which the acetate moiety was replaced with alkylcarbonate functionality has been synthesized. The studies of alkylcarbonate migration on furanoside scaffold have established the stability of alkylcarbonate vs. acetate under various conditions. Generally, alkylcarbonates are more stable than acetate under acidic or neutral conditions whereas under basic conditions they seem to be less stable....
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Tyrosine-based prodrugs of acyclic nucleoside phosphonates
Tichý, Tomáš ; Pomeisl, Karel ; Krečmerová, Marcela ; McKenna, Ch. E.
Prodrug approach based on masking of a phosphonate function by ester linkage to a tyrosine promoiety has been developed. Results demonstrate that tyrosine is a promoiety providing drug conjugates with good chemical stability, bioavailability and efficient activation to active drug species. Another properties like metabolic stability and antiviral activity can be tuned by modification of the carboxyl function of the promoiety. Phosphonate monoester prodrugs were prepared by PyBOP coupling of a protected tyrosine promoiety with suitably derivatized phosphonate function of the parent drug. Phosphonate diester prodrugs were prepared by "synthon" approach, emloying alkylation of purine nucleobase with pre-prepared PME synthons bearing two protected tyrosine promoieties.
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New amphiphilic prodrugs of adefovir and cidofovir
Tichý, Tomáš ; Andrei, G. ; Dračínský, Martin ; Holý, Antonín ; Balzarini, J. ; Snoeck, R. ; Krečmerová, Marcela
New adefovir (PMEA) prodrugs with a pro-moiety consisting of decyl(oxyethyl) chain bearing hydroxyl function(s), hexaethyleneglycol or a (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl unit were prepared from the tetrabutylammonium salt of the phosphonate drug and an appropriate alkyl bromide or tosylate. Analogously, two esters of Cidofovir [(S)-HPMPC] bearing a hexaethyleneglycol moiety were prepared. The antiviral activity of the prodrugs was evaluated in vitro. A loss in the antiviral activities of the hydroxylated decyl(oxyethyl) esters and hexaethyleneglycol esters of PMEA against HIV and herpesviruses. (S)-HPMPC prodrugs exhibited anticytomegalovirus activities in the same range as the parent drug, whereas the anti-HSV and anti-VZV activities were one- to seven-fold lower than that of Cidofovir.
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Cyclic and acyclic phosphonate tyrosine ester prodrugs of acyclic nucleoside phosphonates
Williams, M. ; Krylov, I. S. ; Zakharova, V. M. ; Serpi, M. ; Peterson, L. W. ; Krečmerová, Marcela ; Kashemirov, B. A. ; McKenna, Ch. E.
A series of P-O ester derivatives of HPMPA, HPMPC, PMEA a (R)-PMPDAP was synthesized as potential anti-malarial prodrugs.
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