Enantioselective high-performance liquid chromatography of aryl-substituted oxazolines as an efficient tool for determination of chiral purity of serine medicinal components.

A new approach for the evaluation of chiral purity of serine esterification products bearing long-chain alkyl substituents was developed. The compounds were simply converted to aryl-substituted oxazolines which: (i) facilitates effective chromatographic enantioseparation and (ii) enables direct detection using ultraviolet absorption. The method employs a polysaccharide-based chiral stationary phase and allows enantioseparation of highly stable oxazoline products in less than 6 min using a simple binary mobile phase.

1,2,4-Thiadiazole acyclic nucleoside phosphonates as inhibitors of cysteine dependent enzymes cathepsin K and GSK-3β.

In analogy to antiviral acyclic nucleoside phosphonates, a series of 5-amino-3-oxo-1,2,4-thiadiazol-3(2H)-ones bearing a 2-phosphonomethoxyethyl (PME) or 3-hydroxy-2-(phosphonomethoxy)propyl (HPMP) group at the position 2 of the heterocyclic moiety has been synthesized. Diisopropyl esters of PME- and HPMP-amines have been converted to the N-substituted ureas and then reacted with benzoyl, ethoxycarbonyl, and Fmoc isothiocyanates to give the corresponding thiobiurets, which were oxidatively cyclized to diisopropyl esters of 5-amino-3-oxo-2-PME- or 2-HPMP- 1,2,4-thiadiazol-3(2H)-ones. The phosphonate ester groups were cleaved with bromotrimethylsilane, yielding N-protected phosphonic acids.

Synthesis of fluorinated acyclic nucleoside phosphonates with 5-azacytosine base moiety.

With respect to the strong antiviral activity of ()-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-azacytosine various types of its side chain fluorinated analogues were prepared. The title compound, ()-1-[3-fluoro-2-(phosphonomethoxy)propyl]-5-azacytosine (FPMP-5-azaC) was synthesised by the condensation reaction of ()-2-[(diisopropoxyphosphoryl)methoxy)-3-fluoropropyl -toluenesulfonate with a sodium salt of 5-azacytosine followed by separation of appropriate and regioisomers and ester hydrolysis. Transformations of FPMP-5-azaC to its 5,6-dihydro-5-azacytosine counterpart, amino acid phosphoramidate prodrugs and systems with an annelated five-membered imidazole ring, i.

Simple Syntheses of New Pegylated Trehalose Derivatives as a Chemical Tool for Potential Evaluation of Cryoprotectant Effects on Cell Membrane.

In our work, we developed the synthesis of new polyfunctional pegylated trehalose derivatives and evaluated their cryoprotective effect using flow cytometry. We showed that new compounds (modified trehaloses) bound to appropriate extracellular polymeric cryoprotectants could be helpful as a chemical tool for the evaluation of their potential toxic cell membrane influences. Our aim was to form a chemical tool for the evaluation of cryoprotectant cell membrane influences, which are still not easily predicted during the freezing/thawing process.

Enantioselective resolution of side-chain modified gem-difluorinated alcohols catalysed by Candida antarctica lipase B and monitored by capillary electrophoresis.

An enzymatic alternative to the chemical synthesis of chiral gem-difluorinated alcohols has been developed. The method is highly effective and stereoselective, feasible at laboratory temperature, avoiding the use of toxic heavy metal catalysts which is an important benefit in medicinal chemistry including the synthesis of drugs and drug precursors. Candida antarctica lipases A and B were applied for the enantioselective resolution of side-chain modified gem-difluorinated alcohols, (R)- and (S)-3-benzyloxy-1,1-difluoropropan-2-ols (1a and 1b), compounds serving as chiral building blocks in the synthesis of various bioactive molecules bearing a gem-difluorinated grouping.

Utilization of 1,3-Dioxolanes in the Synthesis of α-branched Alkyl and Aryl 9-[2-(Phosphonomethoxy)Ethyl]Purines and Study of the Influence of α-branched Substitution for Potential Biological Activity.

Syntheses of α-branched alkyl and aryl substituted 9-[2-(phosphonomethoxy)ethyl]purines from substituted 1,3-dioxolanes have been developed. Key synthetic precursors, α-substituted dialkyl [(2-hydroxyethoxy)methyl]phosphonates were prepared via Lewis acid mediated cleavage of 1,3-dioxolanes followed by reaction with dialkyl or trialkyl phosphites. The best preparative yields were achieved under conditions utilizing tin tetrachloride as Lewis acid and triisopropyl phosphite.

Theoretical and experimental study of the antifreeze protein AFP752, trehalose and dimethyl sulfoxide cryoprotection mechanism: correlation with cryopreserved cell viability.

In this work the physico-chemical properties of selected cryoprotectants (antifreeze protein TrxA-AFP752, trehalose and dimethyl sulfoxide) were correlated with their impact on the constitution of ice and influence on frozen/thawed cell viability. The freezing processes and states of investigated materials solutions were described and explained from a fundamental point of view using ab-initio modelling (molecular dynamics, DFT), Raman spectroscopy, Differential Scanning Calorimetry and X-Ray Diffraction. For the first time, in this work we correlated the microscopic view (modelling) with the description of the frozen solution states and put these results in the context of human skin fibroblast viability after freezing and thawing.

New prodrugs of two pyrimidine acyclic nucleoside phosphonates: Synthesis and antiviral activity.

New 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy]pyrimidine (PMEO-DAPy) and 1-[2-(phosphonomethoxy)ethyl]-5-azacytosine (PME-5-azaC) prodrugs were prepared with a pro-moiety consisting of carbonyloxymethyl esters (POM, POC), alkoxyalkyl esters, amino acid phosphoramidates and/or tyrosine. The activity of the prodrugs was evaluated in vitro against different virus families. None of the synthesized prodrugs demonstrated activity against RNA viruses but some of them proved active against herpesviruses [including herpes simplex virus (HSV), varicella-zoster virus (VZV), and human cytomegalovirus (HCMV)].

Syntheses of 1-[2-(Phosphonomethoxy)Alkyl] thymine monophosphates and an evaluation of their inhibitory activity toward human thymidine phosphorylase.

A series of new monophosphates of 1-[2-(phosphonomethoxy)alkyl]thymines, such as PMPTp(,) 3-MeO-PMPTp, HPMPTp, and FPMPTp, were synthesized and tested for their ability to inhibit human thymidine phosphorylase. Kinetic measurements of enzyme activity were performed using thymidine and inorganic phosphate as the substrates. The data show that some monophosphates provide a considerable increase of the multisubstrate inhibitory effect.

Synthesis of ester prodrugs of 9-(S)-[3-hydroxy-2-(phosphonomethoxy)propyl]-2,6-diaminopurine (HPMPDAP) as anti-poxvirus agents.

9-(S)-[3-Hydroxy-2-(phosphonomethoxy)propyl]-2,6-diaminopurine (HPMPDAP) and its cyclic form were selected for further evaluation as potential drug candidates against poxvirus infections. To increase bioavailability of these compounds, synthesis of their structurally diverse ester prodrugs was carried out: alkoxyalkyl (hexadecyloxypropyl, octadecyloxyethyl, hexadecyloxyethyl), pivaloyloxymethyl (POM), 2,2,2-trifluoroethyl, butylsalicylyl, and prodrugs based on peptidomimetics. Most HPMPDAP prodrugs were synthesized in the form of monoesters as well as the corresponding cyclic phosphonate esters.

Pyrimidine acyclic nucleoside phosphonates and phosphorylated analogs. Part 2. Syntheses and investigation of their inhibitory effects towards human thymidine phosphorylase.

Various methods were used in the syntheses of a number of pyrimidine acyclic nucleoside phosphonates and their derivatives such as a nucleophilic fluorination, Suzuki-Miyaura coupling reactions and phosphorylation. These new compounds were further investigated for their potential biological activity. Based on results obtained the ability to inhibit human thymidine phosphorylase some of them was found.

Syntheses of N3-substituted thymine acyclic nucleoside phosphonates and a comparison of their inhibitory effect towards thymidine phosphorylase.

A series of N(3)-substituted thymine acyclic nucleoside phosphonates bearing a number of (phosphonomethoxy)alkyl groups were synthesized and investigated for their ability to inhibit the human thymidine phosphorylase expressed in V79 Chinese hamster cells, as well as thymidine phosphorylase from SD-lymphoma, Escherichia coli and human placenta. In comparison to N(1)- substituted analogues which possess a considerable inhibitory activity towards thymidine phosphorylase from SD-lymphoma, the results showed a marginal inhibitory effect of these compounds. None of the presented N(3)-substituted derivatives possess a significant cytostatic activity.

Syntheses of pyrimidine acyclic nucleoside phosphonates as potent inhibitors of thymidine phosphorylase (PD-ECGF) from SD-lymphoma.

In the present study, we synthesized a series of pyrimidine acyclic nucleoside phosphonates bearing a number of substituents in C-5 position of uracil moiety and in the N-1-side chain. In addition, we have investigated in particular the novel syntheses of fluorinated derivatives substituted in the N-1-side chain and uracil C-5 position because fluorine-containing substituents are often powerful modifiers of chemical and biological properties. The obtained compounds exhibit a considerable inhibitory potency of thymidine phosphorylase from SD-lymphoma.

New modification of the Perkow reaction: halocarboxylate anions as leaving groups in 3-acyloxyquinoline-2,4(1H,3H)-dione compounds.

Substituted 3-(fluoroacyloxy)quinoline-2,4(1H,3H)-diones including 3-(fluoroiodoacetoxy) derivatives react with triethyl phosphite to afford either the product of the Perkow reaction or the corresponding 4-ethoxyquinolin-2(1H)-one. In both reactions, the fluorocarboxylate anion acts as the first observed leaving group. This observation restricts the application of the intramolecular Horner-Wadsworth-Emmons synthesis to modify quinoline-2,4(1H,3H)-diones by the annulation of fluorinated but-2-enolide rings.

Inhibition of thymidine phosphorylase (PD-ECGF) from SD-lymphoma by phosphonomethoxyalkyl thymines.

A series of thymine phosphonomethoxyalkyl derivatives were evaluated for their ability to inhibit thymidine phosphorylase (dThdPase) purified from rat spontaneous T-cell lymphoma. A kinetic study of thymidine phosphorolysis catalyzed by dThdPase was performed with thymidine and/or inorganic phosphate as substrates. Data show that the substantial inhibitory effect of these acyclic nucleotide analogues is decreasing in the order of (R)-FPMPT>(S)-FPMPT>or=(R)-HPMPT>(S)-PMPT>(S)-HPMPT>PMET>or=(R)-PMPT.