Synthesis and characterization of various 5'-dye-labeled ribonucleosides.

Hitherto unknown chromophoric nucleosides are reported. This novel set of visibly coloured dye-labeled 5'-nucleosides, including 1,2,4,5-tetrazine, dicyanomethylene-4H-pyran, benzophenoxazinone, 9,10-anthraquinone and azobenzene chromophores, were prepared mainly under Cu-catalyzed azide-alkyne cycloaddition (CuAAC). The design criteria are outlined. Several derivatives possess in supplement a fluorescence property. The absorption and fluorescence spectra of all coloured nucleosides were recorded to study their potential as visible-range probes. Such nucleodyes are of great interest for future competitive lateral flow test MIP-based strips.

Love Acoustic Wave-Based Devices and Molecularly-Imprinted Polymers as Versatile Sensors for Electronic Nose or Tongue for Cancer Monitoring.

Cancer is a leading cause of death worldwide and actual analytical techniques are restrictive in detecting it. Thus, there is still a challenge, as well as a need, for the development of quantitative non-invasive tools for the diagnosis of cancers and the follow-up care of patients. We introduce first the overall interest of electronic nose or tongue for such application of microsensors arrays with data processing in complex media, either gas (e.g., Volatile Organic Compounds or VOCs as biomarkers in breath) or liquid (e.g., modified nucleosides as urinary biomarkers). Then this is illustrated with a versatile acoustic wave transducer, functionalized with molecularly-imprinted polymers (MIP) synthesized for adenosine-5'-monophosphate (AMP) as a model for nucleosides. The device including the thin film coating is described, then static measurements with scanning electron microscopy (SEM) and electrical characterization after each step of the sensitive MIP process (deposit, removal of AMP template, capture of AMP target) demonstrate the thin film functionality. Dynamic measurements with a microfluidic setup and four targets are presented afterwards. They show a sensitivity of 5 Hz·ppm(-1) of the non-optimized microsensor for AMP detection, with a specificity of three times compared to PMPA, and almost nil sensitivity to 3'AMP and CMP, in accordance with previously published results on bulk MIP.

Evaluation of molecularly imprinted polymers using 2',3',5'-tri-O-acyluridines as templates for pyrimidine nucleoside recognition.

In this paper, we describe the synthesis and evaluation of molecularly imprinted polymers (MIPs), prepared using 2',3',5'-tri-O-acyluridines as 'dummy' templates, for the selective recognition of uridine nucleosides. The MIPs were synthesised using a non-covalent approach with 2,6-bis-acrylamidopyridine (BAAPy) acting as the binding monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent. The MIPs were evaluated in terms of capacity, selectivity and specificity by analytical and frontal liquid chromatography measurements. The results obtained in organic mobile phases suggest that the nucleosides are specifically bound to the polymer by the complementary hydrogen bonding motifs of the binding monomer and the nucleoside bases. The MIPs exhibited relatively high imprinting factors for 2',3',5'-tri-O-acyluridines, while they did not show any binding capacity for other nucleosides lacking the imide moiety on their base. Moreover, the presence of ester-COO groups in the EGDMA cross-linker may lead to the formation of additional hydrogen bonds with the 2',3' and/or 5'-OH of sugar part, allowing enhancement of the recognition of the uridine nucleosides. In aqueous media, results show that the binding is driven by hydrophobic interactions.

Molecularly Imprinted Polymeric Nanoparticles as Drug Delivery System for Tenofovir, an Acyclic Nucleoside Phosphonate Antiviral.

A molecularly imprinted polymer of Tenofovir (1), an FDA-approved acyclic nucleoside phosphonate with antiviral activity, was synthesized using a non-covalent approach. A pre-polymerization complex was formed between (1) and DMAEMA and in-house synthetic N1-[(2-methacryloyloxy)ethyl] thymine, with EGDMA as a cross-linker in an MeCN/H2O (9:1, 1:1) mixture as a porogen, giving an imprinting factor (IF) of 5.5 at 2.10-5 mol/L. Binding parameters were determined by the Freundlich-Langmuir model, Qmax and Ka, and well as the particle morphology for MIP and NIP. Finally, the release profiles, for MIP and NIP, were obtained at 25 °C and 37 °C, which is body temperature, in a phosphate buffer saline, pH 7.4, mimicking the blood pH value, to determine the potential sustained release of our polymeric materials.

Lyotropic liquid crystal emulsions of LAVR-289: Influence of internal mesophase structure on cytotoxicity and in-vitro antiviral activity.

Emerging and reemerging viruses pose significant public health threats, underscoring the urgent need for new antiviral drugs. Recently, a novel family of antiviral acyclic nucleoside phosphonates (ANP) composed of a 4-(2,4-diaminopyrimidin-6-yl)oxy-but-2-enyl phosphonic acid skeleton (O-DAPy nucleobase) has shown promise. Among these, LAVR-289 stands out for its potent inhibitory effects against various DNA viruses. Despite its efficacy, LAVR-289s poor water solubility hampers effective drug delivery. To address this, innovative delivery systems utilizing lipidic derivatives have been explored for various administration routes. Submicron lyotropic liquid crystals (LLCs) are particularly promising drug carriers for the encapsulation, protection, and delivery of lipophilic drugs like LAVR-289. This study focuses on developing submicron-sized lipid mesophase dispersions, including emulsified L2 phase, cubosomes, and hexosomes, by adjusting lipidic compounds such as Dimodan® U/J, Lecithins E80, and Miglyol® 812 N. These formulations aim to enhance the solubility and bioavailability of LAVR-289. In vitro evaluations demonstrated that LAVR-289-loaded LLCs at a concentration of 1 µM efficiently inhibited vaccinia virus in infected human cells, with no observed cytotoxicity. Notably, hexosomes exhibited the most favorable antiviral outcomes, suggesting that the internal mesophase structure plays a critical role in optimizing the therapeutic efficacy of this drug class.

Synthesis of LAVR-289, a new [(Z)-3-(acetoxymethyl)-4-(2,4-diaminopyrimidin-6-yl)oxy-but-2-enyl]phosphonic acid prodrug with pronounced antiviral activity against DNA viruses.

New acyclic pyrimidine nucleoside phosphonate prodrugs with a 4-(2,4-diaminopyrimidin-6-yl)oxy-but-2-enyl]phosphonic acid skeleton (O-DAPy nucleobase) were prepared through a convergent synthesis by olefin cross-metathesis as the key step. Several acyclic nucleoside 4-(2,4-diaminopyrimidin-6-yl)oxy-but-2-enyl]phosphonic acid prodrug exhibited in vitro antiviral activity in submicromolar or nanomolar range against varicella zoster virus (VZV), human cytomegalovirus (HCMV), human herpes virus type 1 (HSV-1) and type 2 (HSV-2), and vaccinia virus (VV), with good selective index (SI). Among them, the analogue 9c (LAVR-289) proved markedly inhibitory against VZV wild-type (TK+) (EC50 0.0035 µM, SI 740) and for thymidine kinase VZV deficient strains (EC50 0.018 µM, SI 145), with a low morphological toxicity in cell culture at 100 µM and acceptable cytostatic activity resulting in excellent selectivity. Compound 9c exhibited antiviral activity against HCMV (EC50 0.021 µM) and VV (EC50 0.050 µM), as well as against HSV-1 (TK-) (EC50 0.0085 µM). Finally, LAVR-289 (9c) deserves further (pre)clinical investigations as a potent candidate broad-spectrum anti-herpesvirus drug.

Molecularly Imprinted Hydrogels Selective to Ribavirin as New Drug Delivery Systems to Improve Efficiency of Antiviral Nucleoside Analogue: A Proof-of-Concept Study with Influenza A Virus.

This study describes the synthesis and evaluation of different imprinted hydrogels using ribavirin as template molecule. Ribavirin serves as a model molecule because it possesses a broad-spectrum antiviral effect against RNA viruses, which are expected as emerging viruses. The choice of monomers enables to stabilize the pre-polymerization complex and to synthesize biocompatible polymers. Predictive studies as well as experimental works conclude similar results on best ribavirin:monomers ratios. Thus, materials exhibit high selective cavities toward ribavirin. These affinities allow to show release profiles drastically different from the non-imprinted ones at two temperatures. The imprinted materials show a sustained profile able to release antiviral for more than 24 h. The hydrogels obtained are biocompatible with model cells retained, human lung epithelial BEAS-2B cells. Cell viability is excellent and pro-inflammatory response is insignificant when imprinted polymers are incubated with cells. Finally, viral tests carried out on Influenza A infected lung cells show that imprinted delivery systems delivering 1 to 3 µg of antiviral have the same efficiency as a medium containing 30 µg mL-1 of active agent. As a very interesting result, the molecularly imprinted polymers as drug delivery systems allow to increase the local concentration of antiviral, to improve their delivery when its bioavailability is low.

Synthesis of imprinted hydrogel microbeads by inverse Pickering emulsion to controlled release of adenosine 5'­monophosphate.

Herein, we propose the synthesis of a microspherical imprinted hydrogel meant for the controlled release of a nucleotide, adenosine 5'-monophosphate (5'-AMP). Indeed, molecularly imprinted polymers-based (MIPs) materials possess remarkable selective molecular recognition ability that mimicks biological systems. MIPs have been used in numerous applications and hold great promise for the vectorization and/or controlled release of therapeutics and cosmetics. But, the conception of imprinted hydrogels-based drug delivery systems that are able to release polar bioactive compounds is explored weakly. Herein, the synthesis of imprinted hydrogel microbeads by inverse Pickering emulsion is detailed. Microspheres showed a large 5'-AMP loading capacity, around 300 mg·g-1, and a high binding capacity comparatively to the non-imprinted counterpart. The MIP had a thermo-responsive release behavior providing sustained release of adenosine 5'-monophosphate in an aqueous buffer simulating both human skin pH and temperature.

Analysis of triacylglycerols on porous graphitic carbon by high temperature liquid chromatography.

The retention behaviour of several triacylglycerols (TAGs) and fats on Hypercarb, a porous graphitic carbon column (PGC), was investigated in liquid chromatography (LC) under isocratic elution mode with an evaporative light scattering detector (ELSD). Mixtures of chloroform/isopropanol were selected as mobile phase for a suitable retention time to study the influence of temperature. The retention was different between PGC and non-aqueous reversed phase liquid chromatography (NARP-LC) on octadecyl phase. The retention of TAGs was investigated in the interval 30-70 degrees C. Retention was greatly affected by temperature: it decreases as the column temperature increases. Selectivity of TAGs was also slightly influenced by the temperature. Moreover, this chromatographic method is compatible with a mass spectrometer (MS) detector by using atmospheric pressure chemical ionisation (APCI): same fingerprints of cocoa butter and shea butter were obtained with LC-ELSD and LC-APCI-MS. These preliminary results showed that the PGC column could be suitable to separate quickly triacylglycerols in high temperature conditions coupled with ELSD or MS detector.

On-line liquid chromatography-electrospray ionisation mass spectrometry for kappa-carrageenan oligosaccharides with a porous graphitic carbon column.

Enzymatically digested oligosaccharides of kappa-carrageenans were separated on a porous graphitic carbon (PGC) column and characterised on-line by electrospray ionisation mass spectrometry (ESI-MS). Two different developing ions were applied. Among them ammonium hydrogencarbonate showed more eluting power as it should on normal anion-exchange stationary phases. The oligosaccharides were detected by ESI-MS as fully deprotonated oligosaccharides.

Tailor-Made Molecularly Imprinted Polymer for Selective Recognition of the Urinary Tumor Marker Pseudouridine.

Pseudouridine (Ψ) is an important urinary cancer biomarker, especially in human colorectal cancer (CRC). Disclosed herein is the first Ψ molecularly imprinted polymer (Ψ-MIP) material obtained from tailor-engineered functional monomers. The resulting MIP imprint exhibits a remarkable imprinting factor greater than 70. It is successfully used for the selective recognition of Ψ in spiked human urine. This selective functionalized material opens the route to the development of inexpensive disposable chemosensors for noninvasive CRC diagnosis and prognosis.

Tandem mass spectrometry for the characterisation of sulphated-phosphorylated analogues of the carbohydrate-protein linkage region of proteoglycans.

Carbohydrate-protein linkage region of proteoglycans is a key oligosaccharide structure because their sulphated and/or phosphorylated analogues control the biosynthesis of glucosaminoglycans or galactosaminoglycans. Therefore, synthesised sulphated and/or phosphorylated analogues were characterised by tandem mass spectrometry in the negative-ion mode. Results demonstrated that the product ion profile was characterised by glycosidic and cross-ring cleavages depending on the position and the type of the charged group (sulphate, phosphate or carboxylate). When the above compounds were sulphated and phosphorylated, the ion found at m/z 79 was the only one that demonstrated a phosphate group on the structure. The data also suggested that when a sodium cation was present in a sulphated and phosphorylated structure, the phosphate group in most cases was neutralised by the sodium cation, and therefore cleaved off the molecule, while the sulphate group was carrying the negative charge.

Characterization of a new methylated beta-cyclodextrin with a low degree of substitution by matrix-assisted laser desorption/ionization mass spectrometry and liquid chromatography using evaporative light scattering detection.

A new methylated beta-cyclodextrin with a low degree of substitution was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and high-performance liquid chromatography (HPLC) with evaporative light scattering detection. Using alpha-cyano-4-hydroxycinnamic acid as the matrix and the thin layer method as the deposition procedure, MALDI-TOF-MS revealed that the mixture was composed of CDs bearing from 2 to 8 methyl groups with an average degree of substitution (DS) of 0.7 (i.e. 0.7 methyl groups per glucopyranose unit). Using a Purospher Star RP-18 endcapped column with acetonitrile-water mobile phase in gradient elution mode, HPLC was employed at analytical scale to obtain a chromatographic fingerprint of the crude mixture and at semi-preparative scale to fractionate it. MALDI-TOF-MS of these fractions revealed that the overall retention of the different derivatives, which depicts their polarity, was mainly driven by the DS and increased with the number of methyl groups on the CD moiety.

Isolation of kappa-carrageenan oligosaccharides using ion-pair liquid chromatography--characterisation by electrospray ionisation mass spectrometry in positive-ion mode.

Oligo-kappa-carrageenans participate as elicitors in the cell-cell recognition process in marine plants. Analytical methods can be usefully applied to gain insight into the biochemistry of these biological processes. Therefore, enzymatically digested oligomers of kappa-carrageenans have been separated and isolated on a Spherisorb ODS1 (250 x 4 mm i.d., particle size 5 microm) column using ion-pair liquid chromatography coupled with an evaporative light scattering detector. Heptylamine (5 mM, pH4) has been selected as the ion-pairing agent and MeOH as the organic modifier in a gradient mode. Overloading the column with 1mg of the mixture, the chromatographic mechanism presented adequate stability. The mobile phase of each isolated oligomer was evaporated and the residue was infused into an electrospray ionisation mass spectrometry (ESIMS) in positive-ion mode with 4:1 MeCN-water as mobile phase. Each ESIMS spectrum presented ions consisting of the oligomer attached with a number of heptylammonium ions depending on the molecule size. In addition, the different m/z values permitted direct detection of the oligomers in ESIMS positive-ion mode. The analytical method developed separated the oligomers up to dotriacontasaccharide.

Artificial receptors for the extraction of nucleoside metabolite 7-methylguanosine from aqueous media made by molecular imprinting.

A series of imprinted polymers targeting nucleoside metabolites, prepared using a template analogue approach, are presented. These were prepared following selection of the optimum functional monomer by solution association studies using (1)H NMR titrations whereby methacrylic acid was shown to be the strongest receptor with and affinity constant of 621±51Lmol(-1)vs. 110±16Lmol(-1) for acrylamide. The best performing polymers were prepared using methanol as porogenic co-solvent and although average binding site affinities were marginally reduced, 2.3×10(4)Lmol(-1)vs. 2.7×10(4)Lmol(-1) measured for a polymer prepared in acetonitrile, these polymers contained the highest number of binding sites, 5.27µmolg(-1)vs. 1.64µmolg(-1), while they also exhibited enhanced selectivity for methylated guanosine derivatives. When applied as sorbents in the extraction of nucleoside derivative cancer biomarkers from synthetic urine samples, significant sample clean-up and recoveries of up to 90% for 7-methylguanosine were achieved.

On-line liquid chromatography electrospray ionization mass spectrometry for the characterization of kappa- and iota-carrageenans. Application to the hybrid iota-/nu-carrageenans.

An on-line liquid chromatography electrospray ionization mass spectrometry (MS) method was developed for the characterization of polymers of kappa- (extracted from Kappaphycus alvarezii), iota-, and hybrid iota-/nu-carrageenans (both extracted from Eucheuma denticulatum) enzymatically digested with specific carrageenase enzymes. Applying either CID MS/MS or in-source fragmentation mechanisms, the results demonstrated that none of the polymers of kappa- or iota-carrageenans existed with their ideal repeating units. On the polymer of kappa-carrageenan, the nonideal structures identified consisted of iota-neocarrabiose sulfate units. On the polymer of iota-carrageenan, the nonideal structures identified consisted of the following: (i) kappa-neocarrabiose sulfate units, (ii) iota-neocarrabiose sulfate units with an additional sulfate group, and (iii) iota-neocarrabiose sulfate units with an additional sulfate and a pyruvate acetal group. For both kappa- and iota-carrageenans, the nonideal structures were randomly distributed on the polymers. The method was then applied for the characterization of a hybrid polymer of iota-/nu-carrageenans, enzymatically digested with iota-carrageenase. The results did not reveal an ideal oligosaccharide of nu-carrageenan, suggesting that the iota-carrageenase enzyme could cleave only reduced "densities" of nu-carrageenan repeating units. In addition, information about the sequence of hybrid iota-/nu-carrageenans from E. denticulatum is deduced.

Matrix-assisted laser desorption/ionisation mass spectrometry for the direct analysis of enzymatically digested kappa- iota- and hybrid iota/nu-carrageenans.

Enzymatically digested oligosaccharides of kappa-, iota- and hybrid iota/nu-carrageenans were analysed using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry in the negative-ion mode. nor-Harmane was used as matrix. Depending on the stock concentration and the laser intensity applied, the oligosaccharides exhibited losses of sulphate units (neutralised by the Na+ ion, and thus non-stable), leaving the primary backbone structure in most cases with only the deprotonated sulphate groups (carrying the negative charge, stable). This meant that kappa- and iota-oligosaccharides could not be easily distinguished from one another since they share the same primary backbone structure. However, for the hybrid iota/nu-oligosaccharides the primary backbone structure could be identified since the nu-carrageenan repeating unit differs from that of the kappa/iota-carrageenan unit. For all types of oligosaccharides, the results indicated cleavage of an anhydrogalactose unit from the non-reducing end. Specifically, for the hybrid oligosaccharides of iota/nu-carrageenans, this type of fragmentation means that the nu-carrageenan unit is not positioned on the non-reducing end of the hybrid oligosaccharides. Dehydration reactions, and exchange reactions of Na+ with K+ and Ca2+, were also observed.

Relative antioxidant capacities of propofol and its main metabolites.

The antioxidant activity of propofol, a widely used anesthetic, has previously been demonstrated, but no study has focused on propofol metabolites although propofol undergoes extensive metabolism. In the present study, the antioxidant properties of propofol and its metabolites were studied by measuring malondialdehyde (MDA) produced from lipid peroxidation by microsomes triggered with several free radical generating systems. True MDA determination was performed using a specific high performance liquid chromatography technique. Gas chromatography-isotope ratio mass spectrometry methodology was also used to assess the antioxidant action in a homogeneous aqueous environment. Propofol, 2,6-di-isopropyl-1,4-quinol (1,4-quinol) metabolite and 3,5-di- tert-butyl-4-hydroxytoluene markedly inhibit lipid peroxidation at concentrations lower than 5 microM. The binding of the glucuroconjugated moiety to either one of two hydroxyl groups of 1,4-quinol lowers the radical scavenging activity. Propofol glucuronide did not exert any radical scavenging activity except when peroxidation was induced with tert-butylhydroperoxide. Our data demonstrate that propofol and its metabolites inhibit lipid peroxidation at concentrations similar to those measured in human plasma during anesthesia. Their antioxidant efficiency is influenced by several factors, including the type of radical initiator involved and the site of radical production.