PURPOSE: We aimed to compare the effects of P-glycoprotein (ABCB1) on the intestinal uptake of tenofovir disoproxil fumarate (TDF), tenofovir alafenamide fumarate (TAF), and metabolites, tenofovir isoproxil monoester (TEM) and tenofovir (TFV), and to study the molecular mechanism of drug-drug interaction (DDI) between sofosbuvir (SOF) and TDF/TAF. METHODS: Bidirectional transport experiments in Caco-2 cells and accumulation studies in precision-cut intestinal slices prepared from the ileal segment of rodent (rPCIS) and human (hPCIS) intestines were performed. RESULTS: TDF and TAF were extensively metabolised but TAF exhibited greater stability. ABCB1 significantly reduced the intestinal transepithelial transfer and uptake of the TFV(TDF) and TFV(TAF)-equivalents. However, TDF and TAF were absorbed more efficiently than TFV and TEM. SOF did not inhibit intestinal efflux of TDF and TAF or affect intestinal accumulation of TFV(TDF) and TFV(TAF)-equivalents but did significantly increase the proportion of absorbed TDF. CONCLUSIONS: TDF and TAF likely produce comparable concentrations of TFV-equivalents in the portal vein and the extent of permeation is reduced by the activity of ABCB1. DDI on ABCB1 can thus potentially affect TDF and TAF absorption. SOF does not inhibit ABCB1-mediated transport of TDF and TAF but does stabilise TDF, albeit without affecting the quantity of TFV(TDF)-equivalents crossing the intestinal barrier. Our data thus suggest that reported increases in the TFV plasma concentrations in patients treated with SOF and TDF result either from a DDI between SOF and TDF that does not involve ABCB1 or from a DDI involving another drug used in combination therapy.

• Klíčová slova
• P-glycoprotein, intestinal permeability, sofosbuvir, tenofovir alafenamide fumarate, tenofovir disoproxil fumarate,
• MeSH
• adenin metabolismus   MeSH
• alanin MeSH
• Caco-2 buňky MeSH
• fumaráty MeSH
• HIV infekce * farmakoterapie   MeSH
• látky proti HIV * MeSH
• lidé MeSH
• P-glykoprotein MeSH
• P-glykoproteiny MeSH
• sofosbuvir terapeutické užití   MeSH
• tenofovir MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adenin MeSH
• alanin MeSH
• fumaráty MeSH
• látky proti HIV * MeSH
• P-glykoprotein MeSH
• P-glykoproteiny MeSH
• sofosbuvir MeSH
• tenofovir MeSH

Understanding the effects of metabolism on the rational design of novel and more effective drugs is still a considerable challenge. To the best of our knowledge, there are no entirely computational strategies that make it possible to predict these effects. From this perspective, the development of such methodologies could contribute to significantly reduce the side effects of medicines, leading to the emergence of more effective and safer drugs. Thereby, in this study, our strategy is based on simulating the electron ionization mass spectrometry (EI-MS) fragmentation of the drug molecules and combined with molecular docking and ADMET models in two different situations. In the first model, the drug is docked without considering the possible metabolic effects. In the second model, each of the intermediates from the EI-MS results is docked, and metabolism occurs before the drug accesses the biological target. As a proof of concept, in this work, we investigate the main antiviral drugs used in clinical research to treat COVID-19. As a result, our strategy made it possible to assess the biological activity and toxicity of all potential by-products. We believed that our findings provide new chemical insights that can benefit the rational development of novel drugs in the future.

• MeSH
• adenin škodlivé účinky   analogy a deriváty   metabolismus   farmakologie   MeSH
• adenosin škodlivé účinky   analogy a deriváty   metabolismus   farmakologie   MeSH
• adenosinmonofosfát škodlivé účinky   analogy a deriváty   metabolismus   farmakologie   MeSH
• alanin škodlivé účinky   analogy a deriváty   metabolismus   farmakologie   MeSH
• amidy škodlivé účinky   metabolismus   farmakologie   MeSH
• antivirové látky škodlivé účinky   metabolismus   farmakologie   MeSH
• chlorochin škodlivé účinky   analogy a deriváty   metabolismus   farmakologie   MeSH
• COVID-19 metabolismus   MeSH
• dusíkaté sloučeniny škodlivé účinky   metabolismus   farmakologie   MeSH
• farmakoterapie COVID-19 * MeSH
• lidé MeSH
• metabolické sítě a dráhy MeSH
• objevování léků * MeSH
• pyraziny škodlivé účinky   metabolismus   farmakologie   MeSH
• pyrrolidiny škodlivé účinky   metabolismus   farmakologie   MeSH
• racionální návrh léčiv MeSH
• ribavirin škodlivé účinky   metabolismus   farmakologie   MeSH
• SARS-CoV-2 účinky léků   metabolismus   MeSH
• simulace molekulového dockingu MeSH
• thiazoly škodlivé účinky   metabolismus   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenin MeSH
• adenosin MeSH
• adenosinmonofosfát MeSH
• alanin MeSH
• amidy MeSH
• antivirové látky MeSH
• chlorochin MeSH
• dusíkaté sloučeniny MeSH
• favipiravir MeSH Prohlížeč
• galidesivir MeSH Prohlížeč
• nitazoxanide MeSH Prohlížeč
• pyraziny MeSH
• pyrrolidiny MeSH
• remdesivir MeSH Prohlížeč
• ribavirin MeSH
• thiazoly MeSH

A set of modified 2'-deoxyribonucleoside triphosphates (dNTPs) bearing a linear or branched alkane, indole or phenyl group linked through ethynyl or alkyl spacer were synthesized and used as substrates for polymerase synthesis of hypermodified DNA by primer extension (PEX). Using the alkyl-linked dNTPs, the polymerase synthesized up to 22-mer fully modified oligonucleotide (ON), whereas using the ethynyl-linked dNTPs, the enzyme was able to synthesize even long sequences of >100 modified nucleotides in a row. In PCR, the combinations of all four modified dNTPs showed only linear amplification. Asymmetric PCR or PEX with separation or digestion of the template strand can be used for synthesis of hypermodified single-stranded ONs, which are monodispersed polymers displaying four different substituents on DNA backbone in sequence-specific manner. The fully modified ONs hybridized with complementary strands and modified DNA duplexes were found to exist in B-type conformation (B- or C-DNA) according to CD spectral analysis. The modified DNA can be replicated with high fidelity to natural DNA through PCR and sequenced. Therefore, this approach has a promising potential in generation and selection of hypermodified aptamers and other functional polymers.

• MeSH
• adenin chemie   metabolismus   MeSH
• aptamery nukleotidové chemická syntéza   genetika   MeSH
• cytosin chemie   metabolismus   MeSH
• deoxyribonukleosidy chemie   genetika   metabolismus   MeSH
• dinukleosidfosfáty chemie   genetika   metabolismus   MeSH
• DNA-dependentní DNA-polymerasy genetika   metabolismus   MeSH
• DNA chemie   genetika   metabolismus   MeSH
• guanin chemie   metabolismus   MeSH
• hydrofobní a hydrofilní interakce MeSH
• párování bází MeSH
• polymerázová řetězová reakce MeSH
• polymery chemická syntéza   metabolismus   MeSH
• replikace DNA * MeSH
• sekvence nukleotidů MeSH
• uracil chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenin MeSH
• aptamery nukleotidové MeSH
• cytosin MeSH
• deoxyribonukleosidy MeSH
• dinukleosidfosfáty MeSH
• DNA-dependentní DNA-polymerasy MeSH
• DNA MeSH
• guanin MeSH
• polymery MeSH
• uracil MeSH

Cytokinins and their sugar or non-sugar conjugates are very active growth-promoting factors in plants, although they occur at very low concentrations. These compounds have been identified in numerous plant species. This review predominantly focuses on 9-substituted adenine-based cytokinin conjugates, both artificial and endogenous, sugar and non-sugar, and their roles in plants. Acquired information about their biological activities, interconversions, and metabolism improves understanding of their mechanisms of action and functions in planta. Although a number of 9-substituted cytokinins occur endogenously, many have also been prepared in laboratories to facilitate the clarification of their physiological roles and the determination of their biological properties. Here, we chart advances in knowledge of 9-substituted cytokinin conjugates from their discovery to current understanding and reciprocal interactions between biological properties and associated structural motifs. Current organic chemistry enables preparation of derivatives with better biological properties, such as improved anti-senescence, strong cell division stimulation, shoot forming, or more persistent stress tolerance compared to endogenous or canonical cytokinins. Many artificial cytokinin conjugates stimulate higher mass production than naturally occurring cytokinins, improve rooting, or simply have high stability or bioavailability. Thus, knowledge of the biosynthesis, metabolism, and activity of 9-substituted cytokinins in various plant species extends the scope for exploiting both natural and artificially prepared cytokinins in plant biotechnology, tissue culture, and agriculture.

• Klíčová slova
• D-arabinoside, cytokinin nucleosides, cytokinin sugar conjugates, disaccharides, glucoside, meta-topolin, plant biotechnology, plant tissue culture, riboside, zeatin,
• MeSH
• adenin chemie   metabolismus   MeSH
• cytokininy biosyntéza   chemie   metabolismus   MeSH
• molekulární struktura MeSH
• rostliny chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• adenin MeSH
• cytokininy MeSH

RNA modifications are being recognized as an essential factor in gene expression regulation. They play essential roles in germ line development, differentiation and disease. In eukaryotic mRNAs, N6-adenosine methylation (m6A) is the most prevalent internal chemical modification identified to date. The m6A pathway involves factors called writers, readers and erasers. m6A thus offers an interesting concept of dynamic reversible modification with implications in fine-tuning the cellular metabolism. In mammals, FTO and ALKBH5 have been initially identified as m6A erasers. Recently, FTO m6A specificity has been debated as new reports identify FTO targeting N6,2'-O-dimethyladenosine (m6Am). The two adenosine demethylases have diverse roles in the metabolism of mRNAs and their activity is involved in key processes, such as embryogenesis, disease or infection. In this article, we review the current knowledge of their function and mechanisms and discuss the existing contradictions in the field. This article is part of a Special Issue entitled: mRNA modifications in gene expression control edited by Dr. Soller Matthias and Dr. Fray Rupert.

• Klíčová slova
• ALKBH5, FTO, RNA demethylase, RNA modification, m(6)A, m(6)A(m),
• MeSH
• adenin analogy a deriváty   metabolismus   MeSH
• alfa-ketoglutarát-dependentní dioxygenasa, AlkB homolog 5 metabolismus   MeSH
• lidé MeSH
• posttranskripční úpravy RNA * MeSH
• RNA genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• 6-methyladenine MeSH Prohlížeč
• adenin MeSH
• alfa-ketoglutarát-dependentní dioxygenasa, AlkB homolog 5 MeSH
• RNA MeSH

Single-stranded model oligodeoxyribonucleotides, each containing a single protonatable base-cytosine, adenine, guanine, or 5-methylcytosine-centrally located in a background of non-protonatable thymine residues, were acid-titrated in aqueous solution, with UV monitoring. The basicity of the central base was shown to depend on the type of the central base and its nearest neighbours and to rise with increasing oligonucleotide length and decreasing ionic strength of the solution. More complex model oligonucleotides, each containing a centrally located 5-methylcytosine base, were comparatively evaluated in single-stranded and double-stranded form, by UV spectroscopy and high-field NMR. The N3 protonation of the 5-methylcytosine moiety in the double-stranded case occurred at much lower pH, at which the duplex was already experiencing general dissociation, than in the single-stranded case. The central guanine:5-methylcytosine base pair remained intact up to this point, possibly due to an unusual alternative protonation on O2 of the 5-methylcytosine moiety, already taking place at neutral or weakly basic pH, as indicated by UV spectroscopy, thus suggesting that 5-methylcytosine sites in double-stranded DNA might be protonated to a significant extent under physiological conditions.

• Klíčová slova
• DNA methylation, methylcytosine, nucleobases, oligonucleotides, protonation,
• MeSH
• 5-methylcytosin metabolismus   MeSH
• adenin metabolismus   MeSH
• guanin metabolismus   MeSH
• jednovláknová DNA * chemie   metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• konformace nukleové kyseliny MeSH
• oligodeoxyribonukleotidy * chemie   metabolismus   MeSH
• osmolární koncentrace MeSH
• protony MeSH
• sekvence nukleotidů MeSH
• thymin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• 5-methylcytosin MeSH
• adenin MeSH
• guanin MeSH
• jednovláknová DNA * MeSH
• oligodeoxyribonukleotidy * MeSH
• protony MeSH
• thymin MeSH

Decades of intensive experimental studies of the recognition of DNA sequences by proteins have provided us with a view of a diverse and complicated world in which few to no features are shared between individual DNA-binding protein families. The originally conceived direct readout of DNA residue sequences by amino acid side chains offers very limited capacity for sequence recognition, while the effects of the dynamic properties of the interacting partners remain difficult to quantify and almost impossible to generalise. In this work we investigated the energetic characteristics of all DNA residue-amino acid side chain combinations in the conformations found at the interaction interface in a very large set of protein-DNA complexes by the means of empirical potential-based calculations. General specificity-defining criteria were derived and utilised to look beyond the binding motifs considered in previous studies. Linking energetic favourability to the observed geometrical preferences, our approach reveals several additional amino acid motifs which can distinguish between individual DNA bases. Our results remained valid in environments with various dielectric properties.

• MeSH
• adenin chemie   metabolismus   MeSH
• aminokyselinové motivy * MeSH
• aminokyseliny chemie   metabolismus   MeSH
• cytosin chemie   metabolismus   MeSH
• databáze proteinů MeSH
• DNA vazebné proteiny chemie   genetika   metabolismus   MeSH
• DNA chemie   genetika   metabolismus   MeSH
• guanin chemie   metabolismus   MeSH
• konformace nukleové kyseliny MeSH
• krystalografie rentgenová MeSH
• molekulární modely MeSH
• statistika jako téma metody   MeSH
• terciární struktura proteinů MeSH
• termodynamika MeSH
• thymin chemie   metabolismus   MeSH
• vazba proteinů MeSH
• vazebná místa genetika   MeSH
• výpočetní biologie metody   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adenin MeSH
• aminokyseliny MeSH
• cytosin MeSH
• DNA vazebné proteiny MeSH
• DNA MeSH
• guanin MeSH
• thymin MeSH

Adenylate cyclase toxin (ACT) is the key virulence factor of Bordetella pertussis that facilitates its invasion into the mammalian body. 9-[2-(Phosphonomethoxy)ethyl]adenine diphosphate (PMEApp), the active metabolite of the antiviral drug bis(POM)PMEA (adefovir dipivoxil), has been shown to inhibit ACT. The objective of this study was to evaluate six novel amidate prodrugs of PMEA, both phenyloxy phosphonamidates and phosphonodiamidates, for their ability to inhibit ACT activity in the J774A.1 macrophage cell line. The two phenyloxy phosphonamidate prodrugs exhibited greater inhibitory activity (50% inhibitory concentration [IC50] = 22 and 46 nM) than the phosphonodiamidates (IC50 = 84 to 3,960 nM). The inhibitory activity of the prodrugs correlated with their lipophilicity and the degree of their hydrolysis into free PMEA in J774A.1 cells. Although the prodrugs did not inhibit ACT as effectively as bis(POM)PMEA (IC50 = 6 nM), they were significantly less cytotoxic. Moreover, they all reduced apoptotic effects of ACT and prevented an ACT-induced elevation of intracellular [Ca(2+)]i. The amidate prodrugs were less susceptible to degradation in Caco-2 cells compared to bis(POM)PMEA, while they exerted good transepithelial permeability in this assay. As a consequence, a large amount of intact amidate prodrug is expected to be available to target macrophages in vivo. This feature makes nontoxic amidate prodrugs attractive candidates for further investigation as novel antimicrobial agents.

• MeSH
• adenin analogy a deriváty   metabolismus   farmakologie   MeSH
• adenylátcyklasový toxin antagonisté a inhibitory   metabolismus   MeSH
• antibakteriální látky metabolismus   farmakologie   MeSH
• Bordetella pertussis účinky léků   růst a vývoj   patogenita   MeSH
• Caco-2 buňky MeSH
• inhibiční koncentrace 50 MeSH
• lidé MeSH
• makrofágy účinky léků   mikrobiologie   MeSH
• mikrobiální testy citlivosti MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• organofosfonáty farmakologie   MeSH
• prekurzory léčiv metabolismus   farmakologie   MeSH
• viabilita buněk účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2-(phosphonomethoxy)ethyl)adenine diphosphate MeSH Prohlížeč
• adefovir dipivoxil MeSH Prohlížeč
• adenin MeSH
• adenylátcyklasový toxin MeSH
• antibakteriální látky MeSH
• organofosfonáty MeSH
• prekurzory léčiv MeSH

1. Nucleotide analogues comprise an important class of drugs used in treatment of viral infections but also cancer. These drugs affect the structural integrity of DNA and activate different pathways and processes in the cell and may directly or indirectly influence the drug metabolizing system. Adefovir dipivoxil (AD) and tenofovir disoproxil (TD) are nucleotide analogues approved for the treatment of chronic hepatitis B and/or HIV/AIDS infection. 2. To evaluate the risk of their drug-drug interactions on the level of drug metabolism, an effect of both compounds on cytochromes P450 expression was studied using cDNA microarrays, real-time RT-PCR and immunoblotting. Mice were given intraperitoneally 25 mg/kg of AD or TD, respectively. As a positive control, a combination of prototypic cytochromes P450 (CYP) inducers, phenobarbital and β-naphthoflavone was chosen. 3. The data obtained showed a significant CYP induction in the positive control group, but no clinically significant induction of CYP genes by AD or TD was observed. Our results support the evidence of safety of AD and TD with respect to drug-drug interactions based on enzyme induction. These findings are important as a plethora of new antivirals of different types are being tested and introduced to clinical practice, mostly to be used in combinations.

• Klíčová slova
• Adefovir, CYP, PMEA, PMPA, antiviral, drug metabolism, induction, tenofovir,
• MeSH
• adenin analogy a deriváty   metabolismus   MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• myši inbrední C57BL MeSH
• organofosfonáty chemie   metabolismus   MeSH
• regulace genové exprese enzymů * MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů MeSH
• stanovení celkové genové exprese MeSH
• systém (enzymů) cytochromů P-450 genetika   metabolismus   MeSH
• tenofovir MeSH
• western blotting MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adefovir dipivoxil MeSH Prohlížeč
• adenin MeSH
• organofosfonáty MeSH
• systém (enzymů) cytochromů P-450 MeSH
• tenofovir MeSH

OBJECTIVE AND DESIGN: Tenofovir (TFV) is used in pregnant women as a part of combination antiretroviral treatment to prevent mother-to-child transmission of HIV infection. We aimed to detect whether TFV and/or its prodrug, tenofovir disoproxil fumarate (TDF), are substrates of ATP-binding cassette (ABC) transporters that are functionally expressed in the placenta, namely P-glycoprotein (ABCB1/MDR1), Breast Cancer Resistance Protein (ABCG2/BCRP) and Multidrug Resistance-Associated Protein 2 (ABCC2/MRP2). We employed in-vitro cell-based assays and in-situ animal model to assess possible role of the efflux transporters in transplacental pharmacokinetics of TFV and TDF. METHODS: In-vitro transport assays were performed in MDCKII cells transduced with human ABCB1, ABCG2 or ABCC2. To quantify the effect of these transporters on TFV/TDF transplacental passage, we employed the in-situ model of dually perfused rat term placenta in open and closed setup. RESULTS: In-vitro assays revealed that TDF is a dual substrate of ABCB1 and ABCG2 but not of ABCC2. In contrast, TFV transport was not influenced by any of these transporters. Applying concentration-dependent studies and selective inhibitors, we further confirmed these findings in situ on the organ level; both ABCB1 and ABCG2 limited mother-to-fetus transfer of TDF whereas TFV transplacental passage was not affected by these ABC transporters. CONCLUSION: We propose limited mother-to-fetus transport of both TFV and TDF. While placental transport of TFV is restricted passively, by physical-chemical properties of the molecule, mother-to-fetus passage of TDF is actively hindered by placental ABCB1 and ABCG2 transporters, pumping this compound from trophoblast back to maternal circulation.

• MeSH
• ABC transportér z rodiny G, člen 2 MeSH
• ABC transportéry metabolismus   MeSH
• adenin analogy a deriváty   metabolismus   farmakokinetika   MeSH
• buněčné linie MeSH
• krysa rodu Rattus MeSH
• látky proti HIV metabolismus   farmakokinetika   MeSH
• lidé MeSH
• nádorové proteiny metabolismus   MeSH
• organofosfonáty metabolismus   farmakokinetika   MeSH
• P-glykoprotein metabolismus   MeSH
• P-glykoproteiny MeSH
• potkani Wistar MeSH
• protein spojený s mnohočetnou rezistencí k lékům 2 MeSH
• proteiny spojené s mnohočetnou rezistencí k lékům metabolismus   MeSH
• tenofovir MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ABC transportér z rodiny G, člen 2 MeSH
• ABC transportéry MeSH
• ABCB1 protein, human MeSH Prohlížeč
• ABCC2 protein, human MeSH Prohlížeč
• ABCG2 protein, human MeSH Prohlížeč
• adenin MeSH
• látky proti HIV MeSH
• nádorové proteiny MeSH
• organofosfonáty MeSH
• P-glykoprotein MeSH
• P-glykoproteiny MeSH
• protein spojený s mnohočetnou rezistencí k lékům 2 MeSH
• proteiny spojené s mnohočetnou rezistencí k lékům MeSH
• tenofovir MeSH