Self-complementary oligodeoxyribonucleotides containing 2'-O-(anthraquinone-2-methyl)adenosine

Incorporation of an intercalating agent into an oligodeoxynucleotide (ODN) has the potential to enhance binding affinity upon duplex formation, to increase ODN hydrophobicity, and to enhance resistance to nuclease hydrolysis. Site-specific intercalation has been achieved through the synthesis of 2'-O-(anthraquinone-2-methyl)adenosine(rA*) and its incorporation into the palindromic dodecanucleotide d(CGCrA*CATGTGCG). Melting temperature, CD spectra, 1D and 2D (DQF-COSY and NOESY) NMR spectra, and molecular models were obtained and compared with the unmodified dodecamer. The data clearly establish that intercalation of the anthraquinone ring into a predominantly B-type helix occurs between the A4-T9 and C5-G8 base pairs, significantly stabilizing the duplex and enhancing the hydrophobicity of the ODN.     

Antiretroviral efficacy and pharmacokinetics of oral bis(isopropyloxycarbonyloxymethyl)-9-(2-phosphonylmethoxypropyl)adenine in mice

To overcome the low oral bioavailability of the highly potent and selective antiretroviral agent (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA), a new lipophilic ester derivative, i.e., the bis(isopropyloxycarbonyloxymethyl)-ester [bis(POC)-PMPA], was prepared. The usefulness of bis(POC)-PMPA as an oral prodrug for PMPA was investigated in the intestinal mucosa Caco-2 cell monolayer model. The total transport of bis(POC)-PMPA was 2.7%, whereas it was less than 0.1% for PMPA. Bis(POC)-PMPA was considerably metabolized inside the epithelial cells, since the majority of the compound was recovered after transport in the form of the monoester metabolite [mono(POC)-PMPA]. In contrast, bis(POC)-PMPA was relatively resistant to degradation at the luminal side of the Caco-2 cells. Pharmacokinetic studies with mice showed that the oral bioavailability of bis(POC)-PMPA (calculated from the curves of the concentration of free PMPA in plasma) was 20%. Neither bis(POC)-PMPA nor mono(POC)-PMPA could be recovered in plasma, suggesting the efficient release of the active drug PMPA after oral administration of bis(POC)-PMPA. Severe combined immunodeficient (SCID) mice infected with Moloney murine sarcoma virus (MSV) and treated orally with bis(POC)-PMPA for 5 or 10 days (dosages, 50, 100, or 200 mg of PMPA equivalent per kg of body weight per day) showed a significant delay in MSV-induced tumor appearance and tumor-associated death. The antiviral efficacy of oral bis(POC)-PMPA was related to the dosage and treatment period and was not significantly different from that of subcutaneous PMPA given at an equivalent dose. The favorable pharmacokinetic profile, marked antiviral efficacy, and low toxicity make bis(POC)-PMPA an attractive oral prodrug of PMPA that should be further pursued in clinical studies with patients infected with human immunodeficiency virus or hepatitis B virus.     

Efficacy of 9-(2-phosphonylmethoxyethyl)adenine treatment against chronic simian immunodeficiency virus infection in macaques

Long-tailed macaques chronically infected with simian immunodeficiency virus (SIV) were treated for 4 or 8 weeks with daily subcutaneous doses of the antiretroviral compound 9-(2-phosphonylmethoxyethyl)adenine (PMEA). The efficacy of PMEA was evaluated by monitoring cell-free virus in plasma, virus titer and viral DNA in peripheral blood mononuclear cells, and absolute numbers of lymphocyte subsets. In mock-treated control macaques, virus titers changed minimally. However, in treated macaques, PMEA exhibited impressive effects, leading to the disappearance of virus in the blood within the first week of treatment and lasting through the fourth week of treatment. The results indicate that PMEA can effectively reduce SIV in chronically infected macaques and offer an optimistic perspective for therapeutic intervention against human immunodeficiency virus infection.     

Capillary electrophoresis separation of the new anti-AIDS agents 9-(2-phosphonylmethoxyethyl)adenine and 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine in mixtures with some monoribonucleotides or the most common deoxynucleotides

The present work describes an electrophoretic method for the separation and determination of the new antivirals, 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and 9-(2-phosphonylmethoxyethyl)-2,9-diaminopurine (PMEDAP) in model mixtures with some monoribonucleotide isomers (3'-AMP, 2'-CMP, 3'-CMP, 3'-GMP, 2'-GMP, 3'-UMP, 5'-GMP, and 5'-UMP) or with the most common deoxynucleotides (dCMP, dCDP, dCTP, dTMP, dTDP, dTTP, dGMP, dGDP, dGTP, dAMP, dADP, dATP). A fused-silica capillary tube, 75 microm ID, 67.8 cm total length (60.3 cm length to the detector), with detection at 210 nm was employed. A hydrodynamic injection for 10 s (1.5 psi vacuum) was utilized to introduce the sample, and 30 kV voltage was applied for the separation. The complete separation of PMEA and PMEDAP from the mononucleotide isomers and deoxynucleotide mixtures is possible in less that 10 min and 25 min, respectively, using 20 mM borate buffer, pH 9.9, with the addition of 10 mM beta-cyclodextrin. Efficiencies of more than 120 000 and resolution higher than 1.9 were reached for each of the compounds studied. This capillary electrophoretic procedure opens the possibility for future determination of PMEA and PMEDAP in cell pool samples.     

Administration of 9-[2-(phosphonomethoxy)propyl]adenine (PMPA) for prevention of perinatal simian immunodeficiency virus infection in rhesus macaques

Simian immunodeficiency virus (SIV) infection of newborn macaques is a useful animal model to explore novel strategies to reduce perinatal human immunodeficiency virus (HIV) infection. The availability of two easily distinguishable virus isolates, SIVmac251 and the simian/human immunodeficiency virus chimera SHIV-SF33, allows tracing the source of infection following inoculation with both viruses by different routes. In the present study, we evaluated the efficacy of pre- and postinoculation treatment regimens with 9-[2-(phosphonomethoxy)propyl]adenine (PMPA) to protect newborn macaques against simultaneous oral SIVmac251 and intravenous SHIV-SF33 inoculation. Untreated newborns became persistently infected following virus inoculation. When three pregnant macaques were given a single subcutaneous dose of PMPA 2 hr before cesarean section, their newborns became SIV-infected following SIV and SHIV inoculation shortly after birth. In contrast, when four newborn macaques were inoculated simultaneously with SIV and SHIV, and started immediately on PMPA treatment for 2 weeks, only one animal became persistently SIV-infected; the remaining three PMPA-treated newborns, however, had some evidence of an initial transient virus infection but were seronegative and healthy at 8 months of age. Our data demonstrate that PMPA treatment can reduce perinatal SIV infection and suggest that similar strategies may also be effective against HIV.     

Potent differentiation-inducing properties of the antiretroviral agent 9-(2-phosphonylmethoxyethyl) adenine (PMEA) in the rat choriocarcinoma (RCHO) tumor cell model

We have compared the splenic responses following immunization with the T cell-independent (TI)-2 antigen native dextran B512 and with a thymus-dependent (TD) protein-dextran conjugate. Interestingly, primary immunization with native dextran induced germinal center (GC) formation in the spleen to the same extent as the protein-dextran conjugate. The GC were antigen-specific as characterized by the presence of peanut agglutinin (PNA)-positive areas that were also binding FITC-conjugated dextran. Dextran-binding B cells were also detected outside the GC as sites of antibody-producing cells. The secondary splenic response to native dextran was suppressed compared to the primary response, with almost no dextran-specific GC or extra-follicular sites with dextran-specific B cells present in the sections. This suppression could be reverted by using cholera toxin (CT) as an adjuvant for the dextran immunizations. Following native dextran immunization with CT adjuvant a secondary splenic GC response similar to a TD secondary splenic GC response was generated, with almost all the dextran-specific B cells located in the GC. Collectively, this indicates that the difference between TI and TD antigen responses is not due to different abilities in inducing GC development, rather the GC reaction is less productive for a TI antigen than for a TD antigen. CT can both increase secondary GC formation in particular for the TI form of dextran and ameliorate the GC reaction, as reflected by increased anti-dextran antibody levels.     

Solid-phase synthesis of oligonucleotides containing site-specific N-(2'-deoxyguanosin-8-yl)-2-(acetylamino)fluorene adducts using 9-fluorenylmethoxycarbonyl as the base-protecting group

Eight oligodeoxyribonucleotides containing a site-specific N-(2'-deoxyguanosin-8-yl)-2-(acetyl-amino)fluorene (dG-C8-AAF) adduct were prepared successfully by solid-phase DNA synthesis using the 2-cyanoethyl N,N-diisopropylphosphoramidites of dA, dC, dG, dT, and dG-C8-AAF, with 9-fluorenyl-methoxycarbonyl (Fmoc) as the base-protecting group. The oligonucleotides were deprotected and released from the support by 1:9 piperidine/MeOH at room temperature for 22-36 h or by 1:1 diisopropylamine in MeOH at 55 degrees C for 15 h, purified by HPLC, and fully characterized. About 6 mg of HPLC-purified d[GTGGCG(C8-AAF)CCAAGT] and 7 mg of d[GTGATG(C8-AAF)ATAAGT] were obtained from the 10-mumol-scale synthesis, and their 1D 1H NMR spectra were consistent with the presence of a dG-C8-AAF adduct. The dG-C8-AAF oligonucleotides were also deacetylated to afford the corresponding dG-C8-AF oligonucleotides. d[GTGGCG(C8-AAF)CCAAGT] formed stable 1:1 duplexes with both the fully complementary 12-mer and a GC-deleted (across the adduct) 10-mer complement, and identical melting temperatures were observed for both duplexes. The multidimensional NMR study of these duplexes is presently under investigation.     

Synthesis and dopamine transporter affinity of 2-(methoxycarbonyl)-9-methyl-3-phenyl-9-azabicyclo[3.3.1]nonane derivatives

A series of 9-methyl-3 beta-phenyl-2-substituted-9-azabicyclo[3.3.1]nonane derivatives were synthesized and evaluated as cocaine-binding site ligands at the dopamine transporter (DAT). The conformation of the bicyclic structures and the stereochemistry of the substituents were determined by NMR and X-ray crystallography. The in vitro binding affinity (Ki) of the 9-azabicyclo[3.3.1]nonane derivatives was measured in rat caudate-putamen tissue, and they were found to be 100-fold (Ki = 2-14 microM) less potent than cocaine and other tropane analogs. From these results it is evident that the cocaine-binding site at the DAT is very sensitive to structural modifications of the unsubstituted methylene bridge [C(6)-C(7)] of cocaine and cocaine-like compounds.     

Safety, pharmacokinetics, and antiretroviral activity of intravenous 9-[2-(R)-(Phosphonomethoxy)propyl]adenine, a novel anti-human immunodeficiency virus (HIV) therapy, in HIV-infected adults

9-[2-(R)-(Phosphonomethoxy)propyl]adenine (PMPA) is a nucleotide analogue with potent antiretroviral activity in vitro and in simian models. A randomized, double-blind, placebo-controlled, dose-escalation clinical trial of intravenous PMPA monotherapy was conducted in 20 human immunodeficiency virus (HIV)-infected adults with CD4 cell counts of >/=200 cells/mm3 and plasma HIV RNA levels of >/=10,000 copies/ml. Two dose levels were evaluated (1 and 3 mg/kg of body weight/day). Ten subjects were enrolled at each dose level (eight randomized to receive PMPA and two randomized to receive placebo). On day 1, a single dose of PMPA or placebo was administered by intravenous infusion. Beginning on study day 8, PMPA or placebo was administered once daily for an additional 7 consecutive days. All subjects tolerated dosing without significant adverse events. Mean peak serum PMPA concentrations were 2.7 +/- 0.9 and 9.1 +/- 2.1 microgram/ml in the 1- and 3-mg/kg cohorts, respectively. Serum concentrations declined in a biexponential fashion, with a terminal half-life of 4 to 8 h. At 3 mg/kg/day, a single infusion of PMPA resulted in a 0.4 log10 median decline in plasma HIV RNA by study day 8. Following 7 consecutive days of study drug administration thereafter, the median changes in plasma HIV RNA from baseline were -1.1, -0.6, and 0.1 log10 in the 3-mg/kg/day, 1-mg/kg/day, and placebo dose groups, respectively. Following the final dose in the 3-mg/kg/day cohort, the reduction in HIV RNA was sustained for 7 days before returning toward baseline. Further studies evaluating an oral prodrug of PMPA are under way.     

Synthetic nucleosides and nucleotides. 40. Selective inhibition of eukaryotic DNA polymerase alpha by 9-(beta-D-arabinofuranosyl)-2-(p-n-butylanilino) adenine 5'-triphosphate (BuAaraATP) and its 2'-up azido analog: synthesis and enzymatic evaluations

Starting from 2',3',5'-tri-O-acetyl-2-iodoadenosine, 9-(beta-D-arabinofuranosyl)-2-(p-n-butylanilino)adenine and its 2'(S)-azido counterparts were synthesized in seven steps. These exhibited only moderate growth-inhibitory effects against mouse leukemic P388 cells (IC50 = 13-24 microM), although 5'-triphosphate derivatives showed strong and selective inhibitory action on calf thymus DNA polymerase alpha, but not on beta- and epsilon-polymerases from eukaryotes.     

Synthesis and biological investigations of 2-(tetrahydropyran-2'-yl) and 2-(tetrahydrofuran-2'-yl)benzimidazoles

A set of benzimidazole derivatives bearing on position 2 a tetrahydropyranyl or tetrahydrofuranyl residue was prepared and tested for antitumoral, anti HIV-1 and other pharmacological activities. While the anti-HIV activity was completely lacking, moderate antitumoral activity was found in a few compounds; particularly the 5,6-dichloro-2-(tetrahydropyran-2-yl)-benzimidazole (8) was able to inhibit the growth of 19 cell lines of humane tumors at near micromolar concentration. On the other hand compounds 4, 6-8 and 10 exhibited significant tracheal relaxant activity in vitro at concentration 3-10 micrograms/ml, thus resulting superior to theophylline and comparable to amrinone.     

Antitumor activity of 2-chloro-9-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl) adenine, a novel deoxyadenosine analog, against human colon tumor xenografts by oral administration

2-Chloro-9-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl) adenine (Cl-F-araA) is a novel deoxyadenosine analog, which inhibits DNA synthesis by inhibiting DNA polymerase alpha and ribonucleotide reductase. Cl-F-araA shows potent antiproliferative activity against several leukemic cell lines including those of human origin and is also effective against murine solid tumors, in particular being curative against colon tumors. PURPOSE: We therefore decided to investigate whether Cl-F-araA is effective against human colon tumors, in particular by oral administration, since it has improved stability compared with other deoxyadenosine analogs. METHODS: Antiproliferative activity in vitro was determined from cell counts. Subcutaneously inoculated xenograft models and a liver micrometastases model were used for assessment of antitumor activity in vivo. RESULTS: Cl-F-araA showed potent antiproliferative activity against four human colon tumor cell lines (HCT116, HT-29, DLD-1, WiDr), with a 50% growth-inhibitory concentration (IC50) of 0.26 microM with a 72-h exposure. This activity was greater than those of fludarabine desphosphate and cladribine, other deoxyadenosine analogs, which showed IC50 values of 19 microM and 0.35 microM, respectively. Cl-F-araA showed potent antitumor activity against four human colon tumor xenograft models (HT-29, WiDr, Co-3, COLO-320DM) in a 5-day daily administration schedule, which was shown to be the most effective of three administration regimens tested (single, twice-weekly, 5-day daily). In particular, oral administration showed significantly superior activity, with a regressive or cytostatic growth curve, compared with intravenous administration. In addition, Cl-F-araA was effective at only one-sixteenth of the maximum dose tested in a 10-day daily administration schedule. Therapeutic efficiency seemed to increase in proportion to the frequency of administration. Cl-F-araA also decreased liver micrometastases created by intrasplenic injection of human colon tumor cells, leading to complete suppression at the maximum dose tested. CONCLUSIONS: These results suggest that Cl-F-araA might be clinically effective against human colon cancers using a daily oral administration schedule.     

Effectiveness of postinoculation (R)-9-(2-phosphonylmethoxypropyl) adenine treatment for prevention of persistent simian immunodeficiency virus SIVmne infection depends critically on timing of initiation and duration of treatment

(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA), an acyclic nucleoside phosphonate analog, is one of a new class of potent antiretroviral agents. Previously, we showed that PMPA treatment for 28 days prevented establishment of persistent simian immunodeficiency virus (SIV) infection in macaques even when therapy was initiated 24 h after intravenous virus inoculation. In the present study, we tested regimens involving different intervals between intravenous inoculation with SIV and initiation of PMPA treatment, as well as different durations of treatment, for the ability to prevent establishment of persistent infection. Twenty-four cynomolgus macaques (Macaca fascicularis) were studied for 46 weeks after inoculation with SIV. All mock-treated control macaques showed evidence of productive infection within 2 weeks postinoculation (p.i.). All macaques that were treated with PMPA for 28 days beginning 24 h p.i. showed no evidence of viral replication following discontinuation of PMPA treatment. However, extending the time to initiation of treatment from 24 to 48 or 72 h p.i. or decreasing the duration of treatment reduced effectiveness in preventing establishment of persistent infection. Only half of the macaques treated for 10 days, and none of those treated for 3 days, were completely protected when treatment was initiated at 24 h. Despite the reduced efficacy of delayed and shortened treatment, all PMPA-treated macaques that were not protected showed delays in the onset of cell-associated and plasma viremia and antibody responses compared with mock controls. These results clearly show that both the time between virus exposure and initiation of PMPA treatment as well as the duration of treatment are crucial factors for prevention of acute SIV infection in the macaque model.     

A comparative study of the thermal stability of oligodeoxyribonucleotides containing 5-substituted 2'-deoxyuridines

Two series of modified oligonucleotides based on the self-complementary dodecamer d(CGCTAATTAGCG) were synthesized. The first contained the -C identical withCCH2R linker at C5 of deoxyuridine at position 4 (T*) of d(CGCT*AATTAGCG) and the second contained the -SR linker. The goal of the study was to evaluate and compare these two types of side chains for suitability as tethers for linking reporter groups to oligonucleotides. Our primary concern was how these tethers would effect duplex stability. The modified nucleosides were synthesized by palladium-mediated coupling reactions between the substituted alkyne and 5'-(4, 4'-dimethoxytrityl)-5-iodo-2'-deoxyuridine and between a disulfide and 5-chloromercurio-2'-deoxyuridine. The C5 deoxyuridine side chains evaluated included C identical with CCH3, C identical with CCH2NHC(O)CH3, C identical with CCH2N(CH3)2, C identical with CCH2N-HC(O)C5H4N, C identical with CCH2NHC(O)C10H15, SCH3, SC6H5 and SCH2CH2NHC(O)CH3. The nucleosides containing these substituents were incorporated into oligo-deoxyribonucleotides by standard phosphoramidite methodology. Melting studies demonstrated that the sequence containing the C identical with CCH3side chain had the highest T m value (59.1 degrees C) in comparison with the control sequence (T m = 55.2 degrees C) and that any additional substituent on C3 of the propynyl group lowered the T m value relative to propynyl. Nevertheless, even the most destabilizing substituent, adamantylcarbamoyl, yielded an oligodeoxyribonucleotide that dissociated with a T m of 54 degrees C, which is only 1.2 degrees C less than the control sequence. In contrast, the thioether substituents led to lower T m values, ranging from as low as 45.1 degrees C for SPh up to 52.2 degrees C for SMe. Replacing the methyl of the SMe substituent with a CH2CH2NHC(O)CH3 tether led to no further reduction in melting temperature. The T m value of the CH2CH2NHC(O)CH3-containing oligonucleotide was less than the natural sequence by 1.6 degrees C/substituent. This is sufficiently small that it is anticipated that the C5 thioether linkage may be as useful as the acetylenic linkage for tethering reporter groups to oligonucleotides. More importantly, the thioether linkage provides a means to position functional groups to interact specifically with opposing complementary (target) sequences.     

Mechanism of inhibition of DNA (cytosine C5)-methyltransferases by oligodeoxyribonucleotides containing 5,6-dihydro-5-azacytosine

A key step in the predicted mechanism of enzymatic transfer of methyl groups from S-adenosyl-l-methionine (AdoMet) to cytosine residues in DNA is the transient formation of a dihydrocytosine intermediate covalently linked to cysteine in the active site of a DNA (cytosine C5)-methyltransferase (DNA C5-MTase). Crystallographic analysis of complexes formed by HhaI methyltransferase (M.HhaI), AdoMet and a target oligodeoxyribonucleotide containing 5-fluorocytosine confirmed the existence of this dihydrocytosine intermediate. Based on the premise that 5,6-dihydro-5-azacytosine (DZCyt), a cytosine analog with an sp3-hybridized carbon (CH2) at position 6 and an NH group at position 5, could mimic the non-aromatic character of the cytosine ring in this transition state, we synthesized a series of synthetic substrates for DNA C5-MTase containing DZCyt. Substitution of DZCyt for target cytosines in C-G dinucleotides of single-stranded or double-stranded oligodeoxyribonucleotide substrates led to complete inhibition of methylation by murine DNA C5-MTase. Substitution of DZCyt for the target cytosine in G-C-G-C sites in double-stranded oligodeoxyribonucleotides had a similar effect on methylation by M. HhaI. Oligodeoxyribonucleotides containing DZCyt formed a tight but reversible complex with M.HhaI, and were consistently more potent as inhibitors of DNA methylation than oligodeoxyribonucleotides identical in sequence containing 5-fluorocytosine. Crystallographic analysis of a ternary complex involving M.HhaI, S-adenosyl-l-homocysteine and a double-stranded 13-mer oligodeoxyribonucleotide containing DZCyt at the target position showed that the analog is flipped out of the DNA helix in the same manner as cytosine, 5-methylcytosine, and 5-fluorocytosine. However, no formation of a covalent bond was detected between the sulfur atom of the catalytic site nucleophile, cysteine 81, and the pyrimidine C6 carbon. These results indicate that DZCyt can occupy the active site of M.HhaI as a transition state mimic and, because of the high degree of affinity of its interaction with the enzyme, it can act as a potent inhibitor of methylation.     

Inhibition of adenosine deaminase by erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) mimics the effect of inescapable shock on escape learning in rats.

Three experiments examined the role of adenosine neuroregulation in the production of shuttle-escape deficits caused by prior exposure to inescapable electric shock in rats (learned helplessness). Intracerebroventricular administration of erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), a selective adenosine deaminase inhibitor, mimicked the effect of earlier inescapable shock at a dose of 2.5 μM in previously restrained rats. Performance deficits produced by EHNA or by earlier exposure to inescapable shock were reversed by intraperitoneal injection of 10 mg/kg caffeine, an adenosine receptor antagonist. Finally, preexposure to an ineffective number of shocks interacted in synergy with an ineffective pretest dose (1.0 μM) of EHNA to maximize shuttle-escape latencies. These data implicate endogenous adenosine neuroregulation as a proximate mechanism in learned helplessness and conservation-withdrawal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and biological investigations of 1-(tetrahydropyran-2'-yl)- and 1-(tetrahydrofuran-2'-yl)benzimidazoles and 1/2-(tetrahydropyran-2'-yl)- and 1/2-(tetrahydrofuran-2'-yl)benzotriazoles

Sets of benzimidazole and benzotriazole derivatives bearing on position 1 or 2 a tetrahydrofuranyl or tetrahydropyranyl moieties were prepared through the addition of the suitable benzazoles on 2,3-dihydrofuran and 3,4-dihydro-2H-pyran. The reactions were carried on either without solvent or in carbon tetrachloride solution. In the last case some peculiar chlorinated side products were isolated and characterized. Twenty compounds were screened for in vitro antitumoral and anti-HIV-1 activities and found poorly active or completely inactive. On the other hand several compounds exhibited good tracheal relaxant activity in vitro; compound 8, 11, 16, 24 and 26 resulted more active than theophylline in this test, while compound 11 was comparable to amrinone till the concentration of 3 micrograms/ml. Finally, compound 5 resulted endowed with a strong diuretic and saluretic activity at the dose of 3 mg/Kg, thus representing a new lead for discovering new diuretic agents.     

Structures of oligonucleotides containing 5-(methoxymethyl)-2'-deoxyuridine determined by NMR spectroscopy

Base pairing of 5-(methoxymethyl)-2'-deoxyuridine (MMdU) opposite either adenine or guanine in a seven base pair oligonucleotide duplex has been studied by NMR spectroscopy. When paired with A, we observe that the MMdU.A base pair adopts Watson-Crick geometry. The methoxymethyl substituent is not held in a fixed conformation and may rotate around the C5-CH2 and CH2-O bonds. Examination of the potential energy as a function of rotation around these bonds indicates the presence of four low energy conformations. No hydrogen bonding is indicated for the methoxymethyl substituent, and the four potential minima result from reduced steric clash. For the MMdU.G base pair, the two bases adopt a wobble geometry which does not change with increasing solvent pH. Similarly, we find four low energy conformations for the methoxymethyl substituent in the major groove of the DNA helix.     

Synthesis of 1-(beta-D-glycopyranosyl)-3-deazapyrimidines from 2-hydroxy and 2-mercaptopyridines

The synthesis of new 4- and 5-substituted-3-cyanopyridine nucleosides has been performed by reacting the silylated pyridines and penta-omicron-acetyl-alpha -D-glycopyranose in dichloroethane in the presence of SnCl4. The free nucleosides were tested for their potential activity against HIV and different types of tumor.