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Sample records for cytotoxic nucleoside analogues

  1. The pivotal role of uridine-cytidine kinases in pyrimidine metabolism and activation of cytotoxic nucleoside analogues in neuroblastoma.

    PubMed

    van Kuilenburg, André B P; Meinsma, Rutger

    2016-09-01

    Uridine-cytidine kinase (UCK) catalyzes the phosphorylation of uridine and cytidine as well as the pharmacological activation of several cytotoxic pyrimidine ribonucleoside analogues. In this study, we investigated the functional role of two isoforms of UCK in neuroblastoma cell lines. Analysis of mRNA coding for UCK1 and UCK2 showed that UCK2 is the most abundantly expressed UCK in a panel of neuroblastoma cell lines. Transient and stable overexpression of UCK2 in neuroblastoma cells increased the metabolism of uridine and cytidine as well as the cytotoxicity of 3-deazauridine. Knockdown of endogenous UCK2 as well as overexpression of UCK1 resulted in decreased metabolism of uridine and cytidine and protected the neuroblastoma cells from 3-deazauridine-induced toxicity. Subcellular localization studies showed that UCK1-GFP and UCK2-GFP were localized in the cell nucleus and cytosol, respectively. However, co-expression of UCK1 with UCK2 resulted in a nuclear localization of UCK2 instead of its normal cytosolic localization, thereby impairing its normal function. The physical association of UCK1 and UCK2 was further demonstrated through pull-down analysis using his-tagged UCK. The discovery that UCK2 is highly expressed in neuroblastoma opens the possibility for selectively targeting neuroblastoma cells using UCK2-dependent pyrimidine analogues, while sparing normal tissues. PMID:27239701

  2. Aberrant Apoptotic Response of Colorectal Cancer Cells to Novel Nucleoside Analogues

    PubMed Central

    Harmse, Leonie; Dahan-Farkas, Nurit; Panayides, Jenny-Lee; van Otterlo, Willem; Penny, Clement

    2015-01-01

    Despite the increased understanding of colorectal cancer and the introduction of targeted drug therapy, the metastatic phase of the disease remains refractory to treatment. Since the deregulation of normal apoptosis contributes to the pathogenesis of colorectal cancer, novel nucleoside analogues were synthesized here and evaluated for their ability to induce apoptosis and cause cell death in two colorectal adeno-carcinoma cell lines, Caco-2 and HT-29. Three novel nucleoside analogues assessed here showed cytotoxic activity, as measured by the MTT assay against both cell lines: the IC50 values ranged between 3 and 37 μM, with Caco-2 cells being more sensitive than HT-29 cells. Compared to camptothecin, the positive control, the nucleoside analogues were significantly less toxic to normal unstimulated leukocytes (p>0.05). Moreover, the nucleosides were able to induce apoptosis as measured by an increase in caspase 8 and caspase 3 activity above that of the control. This was additionally supported by data derived from Annexin V-FITC assays. Despite marginal changes to the mitochondrial membrane potential, all three nucleosides caused a significant increase in cytosolic cytochrome c (p>0.05), with a corresponding decrease in mitochondrial cytochrome c. Morphological analysis of both cell lines showed the rapid appearance of vacuoles following exposure to two of the nucleosides, while a third caused cellular detachment, delayed cytoplasmic vacuolisation and nuclear abnormalities. Preliminary investigations, using the autophagic indicator monodansylcadaverine and chloroquine as positive control, showed that two of the nucleosides induced the formation of autophagic vacuoles. In summary, the novel nucleoside analogues showed selective cytotoxicity towards both cancer cell lines and are effective initiators of an unusual apoptotic response, demonstrating their potential to serve as structural scaffolds for more potent analogues. PMID:26390405

  3. Membrane-permeable Triphosphate Prodrugs of Nucleoside Analogues.

    PubMed

    Gollnest, Tristan; Dinis de Oliveira, Thiago; Rath, Anna; Hauber, Ilona; Schols, Dominique; Balzarini, Jan; Meier, Chris

    2016-04-18

    The metabolic conversion of nucleoside analogues into their triphosphates often proceeds insufficiently. Rate-limitations can be at the mono-, but also at the di- and triphosphorylation steps. We developed a nucleoside triphosphate (NTP) delivery system (TriPPPro-approach). In this approach, NTPs are masked by two bioreversible units at the γ-phosphate. Using a procedure involving H-phosphonate chemistry, a series of derivatives bearing approved, as well as potentially antivirally active, nucleoside analogues was synthesized. The enzyme-triggered delivery of NTPs was demonstrated by pig liver esterase, in human T-lymphocyte cell extracts and by a polymerase chain reaction using a prodrug of thymidine triphosphate. The TriPPPro-compounds of some HIV-inactive nucleoside analogues showed marked anti-HIV activity. For cellular uptake studies, a fluorescent TriPPPro-compound was prepared that delivered the triphosphorylated metabolite to intact CEM cells. PMID:27008042

  4. Relaxed enantioselectivity of human mitochondrial thymidine kinase and chemotherapeutic uses of L-nucleoside analogues.

    PubMed Central

    Verri, A; Priori, G; Spadari, S; Tondelli, L; Focher, F

    1997-01-01

    Our discovery that Herpes virus thymidine kinase (TK) and cellular deoxycytidine kinase lack enantioselectivity, being able to phosphorylate both D- and L-enantiomers of the substrate, suggested the use of unnatural L-nucleoside analogues as antiviral drugs (Herpes, hepatitis and immunodeficiency viruses). Several L-nucleoside analogues have displayed a short-term cytotoxicity much lower than their corresponding D-counterpart. Since the delayed cytotoxicity of a drug often depends on its effects on mitochondrial metabolism, we have investigated the degree of enantioselectivity of human mitochondrial thymidine kinase (mt-TK). We demonstrate that mt-TK does not show an absolute enantioselectivity, being able to recognize, although with lower efficiency, the L-enantiomers of thymidine, deoxycytidine and modified deoxyuridines, such as (E)-5-(2-bromovinyl)-2'-deoxyuridine and 5-iodo-2'-deoxyuridine. Interestingly, the reported negative co-operativity of mt-TK phosphorylating beta-D-2'-deoxythymidine (D-Thd), disappears when the deoxyribose moiety has the inverted configuration, resulting in the preferential phosphorylation of d-Thd even in the presence of high concentrations of the L-enantiomer. This, coupled with the higher Km for beta-L-2'-deoxythymidine (L-Thd), makes mt-TK resistant to high concentrations of L-Thd and L-Thd analogues, minimizing the mitochondria-dependent delayed cytotoxicity that might be caused by the administration of L-nucleoside analogues as antivirals. PMID:9359870

  5. Correlation of nucleoside and nucleobase transporter gene expression with antimetabolite drug cytotoxicity.

    PubMed

    Lu, Xin; Gong, Shimei; Monks, Anne; Zaharevitz, Daniel; Moscow, Jeffrey A

    2002-01-01

    Antimetabolite drugs that inhibit nucleic acid metabolism are widely used in cancer chemotherapy. Nucleoside and nucleobase transporters are important for the cellular uptake of nucleic acids and their corresponding anticancer analogue drugs. Thus, these transporters may play a role both in antimetabolite drug sensitivity, by mediating the uptake of nucleoside analogues, and in antimetabolite drug resistance, by mediating the uptake of endogenous nucleosides that may rescue cells from toxicity. Therefore, we examined the relation of the expression of nucleoside and nucleobase transporters to antimetabolite cytotoxicity. We measured the RNA levels of all eight known nucleoside and nucleobase transporters in 50 cell lines included in the National Cancer Institute's Anticancer Drug Screen panel. RNA levels of concentrative nucleoside transporters (CNTs), equilibrative nucleoside transporters (ENTs) and nucleobase transporters (NCBTs) were determined by quantitative RT-PCR using real-time fluorescence acquisition. This method was validated by measuring the expression of the MDR1 gene, and correlating our results with independently determined measurements of MDR1 RNA levels and protein function in these cell lines. We then correlated the pattern of RNA levels to the pattern of cytotoxicity of anticancer drugs in the NCI drug screen database using the COMPARE analysis. Several hypothesized relations between transporter gene expression and cytotoxicity, based upon known interactions between certain nucleoside analogues and transporter proteins, were not observed, suggesting that expression of individual transporters may not be a significant determinant of the cytotoxicity of these drugs. The most closely correlated drug cytotoxicity patterns to transporter gene expression patterns (where increased expression corresponds to increase sensitivity) included those between CNT1 and O6-methylguanine and between ENT2 and hydroxyurea. We also observed that p53 status influenced

  6. Nucleoside transporters, bcl-2 and apoptosis in CLL cells exposed to nucleoside analogues in vitro.

    PubMed

    Petersen, A J; Brown, R D; Gibson, J; Pope, B; Luo, X F; Schutz, L; Wiley, J S; Joshua, D E

    1996-04-01

    The purine nucleoside analogues fludarabine (F1) and chlorodeoxyadenosine (2-CdA) are considered to be cell cycle specific agents which require DNA synthesis for cytotoxicity. However, their efficacy in the treatment of CLL, an indolent lymphoid malignancy suggests additional mechanisms of action. Like cytosine arabinoside (AraC), F1 and 2-CdA gain access to the cell via a specific nucleoside transporter (NST) protein. To investigate the mode of action of these drugs in CLL, we used a fluorescent ligand for the NST (5'-(SAENTA- x8)-fluorescein) and 3-colour flow cytometry to determine NST expression on CD5+/CD19+ B-cells from the peripheral blood (PB) of patients with CLL. NST levels on these cells was found to be not significantly different from normal control lymphocytes (mean = 485 +/- 425) vs. (mean = 553 +/- 178). Exposure to varying concentrations (0, 3 microM and 30 microM) of F1 and 2-CdA, however, resulted in an upregulation of NST (mean = 1552 +/- 775 with 30 microM FL; mean = 3392 +/- 2197 with 30 microM 2-CdA) after 48. "Large" lymphoid cells (not present in normal PB) were found to express significantly more NST (mean = 2540 +/- 2861) and have a higher proliferative capacity than "small" cells (mean = 357 +/- 517 NST/cell). Incubation of CLL cells with F1 (n = 6) and 2-CdA (n = 8) in vitro over 48 h also resulted in an increase in the proportion of cells in S-phase (0 microM = 0.2 + 2 - 0.1; 30 microM FL = 2.4 +/- 2.0; 30 microM 2-CdA = 3.3 +/- 1.3) and a significant increase in morphologically identifiable apoptosis. Apoptosis was confirmed by flow cytometric DNA analysis (0 microM = 13 +/- 8%; 30 microM FL = 40 +/- 20%; 30 microM 2-CdA = 48 +/- 11%). In situ hybridization using a biotinylated cDNA bcl-2 probe demonstrated that bcl-2 mRNA expression was markedly decreased in treated cells after 24 h. These studies have demonstrated that: (1) NST expression on CLL lymphocytes is low; (2) in vitro exposure to the analogues increases both the level of

  7. Cladribine Analogues via O6-(Benzotriazolyl) Derivatives of Guanine Nucleosides

    PubMed Central

    Satishkumar, Sakilam; Vuram, Prasanna K.; Relangi, Siva Subrahmanyam; Gurram, Venkateshwarlu; Zhou, Hong; Kreitman, Robert J.; Montemayor, Michelle M. Martínez; Yang, Lijia; Kaliyaperumal, Muralidharan; Sharma, Somesh; Pottabathini, Narender; Lakshman, Mahesh K.

    2016-01-01

    Cladribine, 2-chloro-2′-deoxyadenosine, is a highly efficacious clinically used nucleoside for the treatment of hairy cell leukemia. It is also being evaluated against other lymphoid malignancies and has been a molecule of interest for well over half a century. In continuation of our interest on the amide bond-activation in purine nucleosides via the use of (benzotriazol-1yl-oxy)tris(dimethylamino)phosphonium hexafluorophosphate, we have evaluated the use of O6-(benzotriazol-1-yl)-2′-deoxyguanosine as a potential precursor to cladribine and its analogues. These compounds, after appropriate deprotection, were assessed for their biological activities and the data are presented herein. Against hairy cell leukemia (HCL), T-cell lymphoma (TCL), and chronic lymphocytic leukemia (CLL) cladribine was the most active against all. The bromo analogue of cladribine showed comparable activity to the ribose analogue of cladribine against HCL, but was more active against TCL and CLL. The bromo ribo analogue of cladribine possessed activity, but was least active among the C6-NH2-containing compounds. Substitution with alkyl groups at the exocyclic amino group appears detrimental to activity, and only the C6 piperidinyl cladribine analogue demonstrated any activity. Against adenocarcinoma MDA-MB-231 cells, only cladribine and its ribose analogue were most active. PMID:26556315

  8. Evaluation of anti-HIV-1 mutagenic nucleoside analogues.

    PubMed

    Vivet-Boudou, Valérie; Isel, Catherine; El Safadi, Yazan; Smyth, Redmond P; Laumond, Géraldine; Moog, Christiane; Paillart, Jean-Christophe; Marquet, Roland

    2015-01-01

    Because of their high mutation rates, RNA viruses and retroviruses replicate close to the threshold of viability. Their existence as quasi-species has pioneered the concept of "lethal mutagenesis" that prompted us to synthesize pyrimidine nucleoside analogues with antiviral activity in cell culture consistent with an accumulation of deleterious mutations in the HIV-1 genome. However, testing all potentially mutagenic compounds in cell-based assays is tedious and costly. Here, we describe two simple in vitro biophysical/biochemical assays that allow prediction of the mutagenic potential of deoxyribonucleoside analogues. The first assay compares the thermal stabilities of matched and mismatched base pairs in DNA duplexes containing or not the nucleoside analogues as follows. A promising candidate should display a small destabilization of the matched base pair compared with the natural nucleoside and the smallest gap possible between the stabilities of the matched and mismatched base pairs. From this assay, we predicted that two of our compounds, 5-hydroxymethyl-2'-deoxyuridine and 5-hydroxymethyl-2'-deoxycytidine, should be mutagenic. The second in vitro reverse transcription assay assesses DNA synthesis opposite nucleoside analogues inserted into a template strand and subsequent extension of the newly synthesized base pairs. Once again, only 5-hydroxymethyl-2'-deoxyuridine and 5-hydroxymethyl-2'-deoxycytidine are predicted to be efficient mutagens. The predictive potential of our fast and easy first line screens was confirmed by detailed analysis of the mutation spectrum induced by the compounds in cell culture because only compounds 5-hydroxymethyl-2'-deoxyuridine and 5-hydroxymethyl-2'-deoxycytidine were found to increase the mutation frequency by 3.1- and 3.4-fold, respectively. PMID:25398876

  9. Acyclic nucleoside/nucleotide analogues with an imidazole ring skeleton.

    PubMed

    Chen, H M; Hosmane, R S

    2001-08-01

    Syntheses of a few acyclic nucleoside and acyclic nucleoside phosphonate analogues containing an imidazole ring have been reported. These analogues include methyl 1-(2-hydroxyethoxymethyl)imidazole-4, 5-dicarbo-xylate (1), 4,5-dicarbamoyl-1-(2-hydroxyethoxymethyl)imidazole (2), 4,5-dicyano-1-(2-hydroxyethoxymethyl)imidazole (4), Methyl 1-(2-bromoethoxymethyl)imidazole-4,5-dicarboxylate (7), 4,5-dicyano-(2-bromoethoxymethyl)imidazole (8), and Methyl 1-(2-phosphonomethoxyethyl)imidazole (10). Also reported are a few potential prodrugs of the above compounds, including the acetyl derivatives 5 and 6 (of 1 and 4, respectively), and the diethyl phosphonate ester 9 (of 10). In addition, the corresponding benzyl-protected precursors 11 and 12 (of 1 and 4, respectively), along with their common hydrolysis product, 1-(2-benzyloxy-ethoxymethyl)-4,5-imidazoledicarboxylic acid (3), are reported. Another potential prodrug included in the list is 1-(2-acetoxyethyl)-4,5-dicyanoimidazole (15). The compounds were screened for in vitro antiviral activity against a wide variety of herpes and respiratory viruses. The most active compound was the phosphonate analogue 9 which exhibited an anti-measles virus activity with an EC50 of <2.5 microg/mL and an SI value of > 176. PMID:11554548

  10. Synthesis of Methylenecyclopropane Analogues of Antiviral Nucleoside Phosphonates

    PubMed Central

    Yan, Zhaohua; Zhou, Shaoman; Kern, Earl R.; Zemlicka, Jiri

    2006-01-01

    Synthesis of methylenecyclopropane analogues of nucleoside phosphonates 6a, 6b, 7a and 7b is described. Cyclopropyl phosphonate 8 was transformed in four steps to methylenecyclopropane phosphonate 16. The latter intermediate was converted in seven steps to the key Z- and E-methylenecyclopropane alcohols 23 and 24 separated by chromatography. Selenoxide eliminations (15 → 16 and 22 → 23 + 24) were instrumental in the synthesis. The Z- and E-isomers 23 and 24 were transformed to bromides 25a and 25b which were used for alkylation of adenine and 2-amino-6-chloropurine to give intermediates 26a, 26b, 26c and 26d. Acid hydrolysis provided the adenine and guanine analogues 6a, 6b, 7a and 7b. Phosphonates 6b and 7b are potent inhibitors of replication of Epstein-Barr virus (EBV). PMID:16758001

  11. Cross-linked polymeric nanogel formulations of 5'-triphosphates of nucleoside analogues: role of the cellular membrane in drug release.

    PubMed

    Vinogradov, Serguei V; Kohli, Ekta; Zeman, Arin D

    2005-01-01

    Activation of cytotoxic nucleoside analogues in vivo depends primarily on their cell-specific phosphorylation. Anticancer chemotherapy using nucleoside analogues may be significantly enhanced by intracellular administration of active phosphorylated drugs. However, the cellular transport of anionic compounds is very ineffective and restricted by many drug efflux transporters. Recently developed cationic nanogel carriers can encapsulate large amounts of nucleoside 5'-triphosphates that form polyionic complexes with protonated amino groups on the polyethylenimine backbone of the nanogels. In this paper, the 5'-triphosphate of an antiviral nucleoside analogue, 3'-azido-2',3'-dideoxythymidine (AZT), was efficiently synthesized and its complexes with nanogels were obtained and evaluated as potential cytotoxic drug formulations for treatment of human breast carcinoma cells. A selective phosphorylating reagent, tris-imidazolylphosphate, was used to convert AZT into the nucleoside analogue 5'-triphosphate using a one-pot procedure. The corresponding 3'-azido-2',3'-dideoxythymidine 5'-triphosphate (AZTTP) was isolated with high yield (75%). Nanogels encapsulated up to 30% of AZTTP by weight by mixing solutions of the carrier and the drug. The AZTTP/nanogel formulation showed enhanced cytotoxicity in two breast cancer cell lines, MCF-7 and MDA-MB-231, demonstrating IC50 values 130-200 times lower than those values for AZT alone. The exact mechanism of drug release from nanogels remains unclear. One mechanism could involve interaction with negatively charged counterions. A high affinity of nanogels to isolated cellular membranes has been observed, especially for nanogels made of amphiphilic block copolymer, Pluronic P85. Cellular trafficking of nanogel particles, contrasted by polyethylenimine-coordinated copper(II) ions, was studied by transmission electron microscopy (TEM), which revealed membranotropic properties of nanogels. A substantial release of encapsulated drug was

  12. Novel inhibitors of Mycobacterium tuberculosis growth based on modified pyrimidine nucleosides and their analogues

    NASA Astrophysics Data System (ADS)

    Shmalenyuk, E. R.; Kochetkov, S. N.; Alexandrova, L. A.

    2013-09-01

    The review summarizes data on the synthesis and antituberculosis activity of pyrimidine nucleoside derivatives and their analogues. Enzymes from M. tuberculosis as promising targets for prototypes of new-generation drugs are considered. Nucleosides as inhibitors of drug-resistant M. tuberculosis strains are characterized. The bibliography includes 101 references.

  13. Synthesis and cytotoxic activity of acetogenin analogues.

    PubMed

    Rodier, S; Le Huérou, Y; Renoux, B; Doyon, J; Renard, P; Pierré, A; Gesson, J P; Grée, R

    2000-06-19

    A set of 16 new simplified analogues of acetogenins has been designed based on: (i) the replacement of the bis THF moiety of these natural products by an ethylene glycol bis ether unit; (ii) the introduction of different lipophilic side chains (alkyl, aryl, dialkylamino, O-cholesteryl); (iii) the presence of the same terminal isolactone. In vitro cytotoxic activity against L1210 leukemia is reported. PMID:10890167

  14. Testing nucleoside analogues as inhibitors of Bacillus anthracis spore germination in vitro and in macrophage cell culture.

    PubMed

    Alvarez, Zadkiel; Lee, Kyungae; Abel-Santos, Ernesto

    2010-12-01

    Bacillus anthracis, the etiological agent of anthrax, has a dormant stage in its life cycle known as the endospore. When conditions become favorable, spores germinate and transform into vegetative bacteria. In inhalational anthrax, the most fatal manifestation of the disease, spores enter the organism through the respiratory tract and germinate in phagosomes of alveolar macrophages. Germinated cells can then produce toxins and establish infection. Thus, germination is a crucial step for the initiation of pathogenesis. B. anthracis spore germination is activated by a wide variety of amino acids and purine nucleosides. Inosine and l-alanine are the two most potent nutrient germinants in vitro. Recent studies have shown that germination can be hindered by isomers or structural analogues of germinants. 6-Thioguanosine (6-TG), a guanosine analogue, is able to inhibit germination and prevent B. anthracis toxin-mediated necrosis in murine macrophages. In this study, we screened 46 different nucleoside analogues as activators or inhibitors of B. anthracis spore germination in vitro. These compounds were also tested for their ability to protect the macrophage cell line J774a.1 from B. anthracis cytotoxicity. Structure-activity relationship analysis of activators and inhibitors clarified the binding mechanisms of nucleosides to B. anthracis spores. In contrast, no structure-activity relationships were apparent for compounds that protected macrophages from B. anthracis-mediated killing. However, multiple inhibitors additively protected macrophages from B. anthracis. PMID:20921305

  15. Carbocyclic nucleoside analogues: classification, target enzymes, mechanisms of action and synthesis

    NASA Astrophysics Data System (ADS)

    Matyugina, E. S.; Khandazhinskaya, A. P.; Kochetkov, Sergei N.

    2012-08-01

    Key biological targets (S-adenosyl-L-homocysteine hydrolase, telomerase, human immunodeficiency virus reverse transcriptase, herpes virus DNA polymerase and hepatitis B virus DNA polymerase) and the mechanisms of action of carbocyclic nucleoside analogues are considered. Structural types of analogues are discussed. Methods of synthesis for the most promising compounds and the spectrum of their biological activities are described. The bibliography includes 126 references.

  16. Transition State Analogues of Purine Nucleoside Phosphorylase: the Work of Vernon L. Schramm

    PubMed Central

    Kresge, Nicole; Simoni, Robert D.; Hill, Robert L.

    2010-01-01

    Transition State Analogue Inhibitors of Purine Nucleoside Phosphorylase from Plasmodium falciparum (Kicska, G. A., Tyler, P. C., Evans, G. B., Furneaux, R. H., Kim, K., and Schramm, V. L. (2002) J. Biol. Chem. 277, 3219–3225) Purine-less Death in Plasmodium falciparum Induced by Immucillin-H, a Transition State Analogue of Purine Nucleoside Phosphorylase (Kicska, G. A., Tyler, P. C., Evans, G. B., Furneaux, R. H., Schramm, V. L., and Kim, K. (2002) J. Biol. Chem. 277, 3226–3231) Achieving the Ultimate Physiological Goal in Transition State Analogue Inhibitors for Purine Nucleoside Phosphorylase (Lewandowicz, A., Tyler, P. C., Evans, G. B., Furneaux, R. H., and Schramm, V. L. (2003) J. Biol. Chem. 278, 31465–31468)

  17. [Synthesis, conformation, and spectroscopy of nucleoside analogues concerning their antiviral activity].

    PubMed

    Kuśmierek, Jarosław T; Stolarski, Ryszard

    2015-01-01

    Chemically modified analogues of nucleosides and nucleotides, have been thoroughly investigated since the discovery of DNA double helix by Watson and Crick in 1953 (Nature 171: 737). Chemical structures, first of all tautomerism, of the nucleic acid bases, as well as the conformations of the nucleic acids constituents, determine the secondary and tertiary structures of DNA and RNA polymers. Similarly, structural and dynamic parameters of nucleoside derivatives determine their biological activity in mutagenesis, neoplastic transformation, as well as antiviral or anticancer properties. In this review, a multidisciplinary approach of Prof. David Shugar's group is presented in the studies on nucleosides and nucleotides. It consists in chemical syntheses of suitable analogues, measurements of physicochemical and spectral parameters, conformational analysis by means of nuclear magnetic resonance (NMR) and X-ray diffraction, as well as characteristics of the nucleoside analogues as inhibitors of some selected, target enzymes, crucial in respect to antiviral activity of the analogues. These long-lasting studies follows upon the line of the main paradigm of molecular biophysics, i. e. structure-activity relationship. PMID:26677575

  18. Synthesis of phosphonate analogues of the antiviral cyclopropane nucleoside A-5021.

    PubMed

    Onishi, Tomoyuki; Sekiyama, Takaaki; Tsuji, Takashi

    2005-01-01

    A series of phosphonate analogues of the antiviral cyclopropane nucleoside A-5021 were synthesized from (1S*, 7R*)-3,5-dioxa-4,4-diphenylbicyclo[5. 1.0]octane-l-methanol by a 10-step process. In contrast to the potent antiherpetic activity of A-5021, they were all devoid of antiviral activity. PMID:16270661

  19. Chromophoric Nucleoside Analogues: Synthesis and Characterization of 6-Aminouracil-Based Nucleodyes.

    PubMed

    Freeman, Noam S; Moore, Curtis E; Wilhelmsson, L Marcus; Tor, Yitzhak

    2016-06-01

    Nucleodyes, visibly colored chromophoric nucleoside analogues, are reported. Design criteria are outlined and the syntheses of cytidine and uridine azo dye analogues derived from 6-aminouracil are described. Structural analysis shows that the nucleodyes are sound structural analogues of their native nucleoside counterparts, and photophysical studies demonstrate that the nucleodyes are sensitive to microenvironmental changes. Quantum chemical calculations are presented as a valuable complementary tool for the design of strongly absorbing nucleodyes, which overlap with the emission of known fluorophores. Förster critical distance (R0) calculations determine that the nucleodyes make good FRET pairs with both 2-aminopurine (2AP) and pyrrolocytosine (PyC). Additionally, unique tautomerization features exhibited by 5-(4-nitrophenylazo)-6-oxocytidine (8) are visualized by an extraordinary crystal structure. PMID:27128151

  20. Solution conformations of nucleoside analogues exhibiting antiviral activity against human immunodeficiency virus

    NASA Astrophysics Data System (ADS)

    Dijkstra, Sandra; Benevides, James M.; Thomas, George J.

    1991-01-01

    The molecular-conformational basis for HIV-1 antiviral activity of dideoxynucleoside analogues is unknown. A recent proposal by van Roey [1] that furanose sugar puckering in the C2' -endo family (namely C3' -exo) may account for the enhanced anti-HIV-1 activity of azidothymidine (AZT), dideoxythymidine (ddT) and dideoxycytidine (ddC) has been tested by conformational analysis of these and related agents, using laser Raman spectroscopy of their solutions and crystal structures. The results show that nucleoside analogues exhibiting anti-HIV-1 activity, including AZT, ddT and ddC, exist in solution with C3' -endo as the predominating sugar pucker. The C3' -endo solution conformations differ fundamentally from the C3' -exo conformations observed in the corresponding crystal structures. Accordingly, the crystal conformation cannot be responsible for enhanced recognition of these agents, either by nucleoside kinase or reverse transcriptase, as a mechanism to explain antiviral activity. The present findings suggest that C3' -endo sugear pucker, rather than C3' -exo pucker, or other puckers of the C2' -endo family, is more probably the required conformation for antivaral activity. The present work also shows that nucleoside phosphorylation does not, in general, change the preferred solution conformation of a nucleoside. Therefore, C3' -endo sugar pucker is likely to be the preferred conformation for both nucleoside kinase and reverse transcriptase recognition. In this study, the list of thymidine nucleoside conformation markers available from Raman spectra is extended and additional group frequency assignments for C3' -azido, C3' -deoxy and related nucleoside derivatives are provided.

  1. Carbacaprazamycins: Chemically Stable Analogues of the Caprazamycin Nucleoside Antibiotics.

    PubMed

    Ichikawa, Satoshi; Yamaguchi, Mayumi; Hsuan, Lee Shang; Kato, Yuta; Matsuda, Akira

    2015-04-10

    Carbacaprazamycins, which are chemically stable analogues of caprazamycins, were designed and synthesized. These analogues were active against drug-resistant bacterial pathogens such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, and their activities were comparable to those of the parent caprazamycins. The effect of treatment with carbacaprazamycin on morphological changes in S. aureus indicated that the mode of action was completely different from those of existing peptidoglycan inhibitors. PMID:27622529

  2. Polymerization of the cyclic pyrophosphates of nucleosides and their analogues

    NASA Technical Reports Server (NTRS)

    Tohidi, Mahrokh; Orgel, Leslie E.

    1990-01-01

    When 2-prime-deoxythymidine 3-prime, 5-prime-cyclic diphosphate, or the cyclic pyrophosphates of the acyclic nucleoside analogs II and IV are heated to 65-85 C in the presence of imidazole, oligomers with lengths up to 20-30 are formed in excellent yield. This reaction provides a useful source of oligomers for use as templates in aqueous condensation reactions. In the absence of evidence to the contrary, it is assumed that the oligomers are atactic. The potential significance of this reaction in prebiotic chemistry is discussed.

  3. Synthesis and cytotoxic activities of semisynthetic zearalenone analogues.

    PubMed

    Tadpetch, Kwanruthai; Kaewmee, Benyapa; Chantakaew, Kittisak; Kantee, Kawalee; Rukachaisirikul, Vatcharin; Phongpaichit, Souwalak

    2016-08-01

    Zearalenone is a β-resorcylic acid macrolide with various biological activities. Herein we report the synthesis and cytotoxic activities of 34 zearalenone analogues against human oral epidermoid carcinoma (KB) and human breast adenocarcinoma (MCF-7) cells as well as noncancerous Vero cells. Some zearalenone analogues showed moderately enhanced cytotoxic activities against the two cancer cell lines. We have discovered the potential lead compounds with diminished or no cytotoxicity to Vero cells. Preliminary structure-activity relationship studies revealed that the double bond at the 1' and 2' positions of zearalenone core was crucial for cytotoxic activities on both cell lines. In addition, for zearalenol analogues, the unprotected hydroxyl group at C-2 and an alkoxy substituent at C-4 played key roles on cytotoxic effects of both cell lines. PMID:27311894

  4. Synthesis and Cytotoxicity of Semisynthetic Withalongolide A Analogues

    PubMed Central

    2013-01-01

    The natural product withaferin A exhibits potent antitumor activity and other diverse pharmacological activities. The recently discovered withalongolide A, a C-19 hydroxylated congener of withaferin A, was recently reported to possess cytotoxic activity against head and neck squamous cell carcinomas. Semisynthetic acetylated analogues of withalongolide A were shown to be considerably more cytotoxic than the parent compound. To further explore the structure–activity relationships, 20 new semisynthetic analogues of withalongolide A were synthesized and evaluated for cytotoxic activity against four different cancer cell lines. A number of derivatives were found to be more potent than the parent compound and withaferin A. PMID:24273633

  5. Anti‐flavivirus Activity of Different Tritylated Pyrimidine and Purine Nucleoside Analogues

    PubMed Central

    Serpi, Michaela; Slusarczyk, Magdalena; Ferrari, Valentina; Pertusati, Fabrizio; Meneghesso, Silvia; Derudas, Marco; Farleigh, Laura; Zanetta, Paola; Bugert, Joachim

    2016-01-01

    Abstract A series of tritylated and dimethoxytritylated analogues of selected pyrimidine and purine nucleosides were synthesized and evaluated for their in vitro inhibitory activity against two important members of the genus Flavivirus in the Flaviviridae family, the yellow fever (YFV) and dengue viruses (DENV). Among all compounds tested, the 5′‐O‐tritylated and the 5′‐O‐dimethoxytritylated 5‐fluorouridine derivatives exerted potency against YFV. Interestingly in the series of purine analogues, the 5′O, N‐bis‐tritylated fludarabine derivative revealed strong inhibitory activity against DENV at μm concentrations, however significantly weaker potency against YFV. PMID:27551659

  6. Anti-flavivirus Activity of Different Tritylated Pyrimidine and Purine Nucleoside Analogues.

    PubMed

    McGuigan, Christopher; Serpi, Michaela; Slusarczyk, Magdalena; Ferrari, Valentina; Pertusati, Fabrizio; Meneghesso, Silvia; Derudas, Marco; Farleigh, Laura; Zanetta, Paola; Bugert, Joachim

    2016-06-01

    A series of tritylated and dimethoxytritylated analogues of selected pyrimidine and purine nucleosides were synthesized and evaluated for their in vitro inhibitory activity against two important members of the genus Flavivirus in the Flaviviridae family, the yellow fever (YFV) and dengue viruses (DENV). Among all compounds tested, the 5'-O-tritylated and the 5'-O-dimethoxytritylated 5-fluorouridine derivatives exerted potency against YFV. Interestingly in the series of purine analogues, the 5'O, N-bis-tritylated fludarabine derivative revealed strong inhibitory activity against DENV at μm concentrations, however significantly weaker potency against YFV. PMID:27551659

  7. In-Gene Quantification of O(6)-Methylguanine with Elongated Nucleoside Analogues on Gold Nanoprobes.

    PubMed

    Trantakis, Ioannis A; Nilforoushan, Arman; Dahlmann, Heidi A; Stäuble, Celine K; Sturla, Shana J

    2016-07-13

    Exposure of DNA to chemicals can result in the formation of DNA adducts, a molecular initiating event in genotoxin-induced carcinogenesis. O(6)-Methylguanine (O(6)-MeG) is a highly mutagenic DNA adduct that forms in human genomic DNA upon reaction with methylating agents of dietary, environmental, or endogenous origin. In this work, we report the design and synthesis of novel non-natural nucleoside analogues 1'-β-[1-naphtho[2,3-d]imidazol-2(3H)-one)]-2'-deoxy-d-ribofuranose and 1'-β-[1-naphtho[2,3-d]imidazole]-2'-deoxy-d-ribofuranose and their use for quantifying O(6)-MeG within mutational hotspots of the human KRAS gene. The novel nucleoside analogues were incorporated into oligonucleotides conjugated to gold nanoparticles to comprise a DNA hybridization probe system for detecting O(6)-MeG in a sequence-specific manner on the basis of colorimetric readout of the nanoparticles. The concept described herein is unique in utilizing new nucleoside analogues with elongated hydrophobic surfaces to successfully measure in-gene abundance of O(6)-MeG in mixtures with competing unmodified DNA. PMID:27314828

  8. Analogues of luteinizing hormone-releasing hormone containing cytotoxic groups.

    PubMed Central

    Janáky, T; Juhász, A; Bajusz, S; Csernus, V; Srkalovic, G; Bokser, L; Milovanovic, S; Redding, T W; Rékási, Z; Nagy, A

    1992-01-01

    In an attempt to produce better cytotoxic analogues, chemotherapeutic antineoplastic radicals including an alkylating nitrogen mustard derivative of D-phenylalanine (D-melphalan), reactive cyclopropane, anthraquinone derivatives [2-(hydroxymethyl)anthraquinone and the anticancer antibiotic doxorubicin], and an antimetabolite (methotrexate) were coupled to suitably modified agonists and antagonists of luteinizing hormone-releasing hormone (LH-RH). Analogues with D-lysine6 and D-ornithine6 or N epsilon-(2,3-diaminopropionyl)-D-lysine and N delta-(2,3-diaminopropionyl)-D-ornithine were used as carriers for one or two cytotoxic moieties. The enhanced biological activities produced by the incorporation of D amino acids into position 6 of the agonistic analogues were further increased by the attachment of hydrophobic cytotoxic groups, resulting in compounds with 10-50 times higher activity than LH-RH. Most of the monosubstituted agonistic analogues showed high affinities for the membrane receptors of human breast cancer cells, while the receptor binding affinities of peptides containing two cytotoxic side chains were lower. Antagonistic carriers [Ac-D-Nal(2)1,D-Phe(4Cl)2,D-Trp3,Arg5,D-Lys6,D-Ala10] LH-RH [where Nal(2) is 3-(2-naphthyl)alanine], [Ac-D-Nal(2)1,D-Phe(4Cl)2,D-Trp3,Arg5,N epsilon-(2,3-diaminopropionyl)-D-Lys6,D-Ala10]LH-RH, and their D-Pal(3)3 homologs [Pal(3) is 3-(3-pyridyl)alanine] as well as [Ac-D-Nal(2)1,D-Phe(4Cl)2,D-Pal(3)3,Tyr5,N epsilon-(2,3-diamino-propionyl)-D-Lys6,D-Ala10]LH-RH were linked to cytotoxic compounds. The hybrid molecules inhibited ovulation in rats at doses of 10 micrograms and suppressed LH release in vitro. The receptor binding of cytotoxic analogues was decreased compared to the precursor peptides, although analogues with 2-(hydroxymethyl)anthraquinone hemiglutarate had high affinities. All of the cytotoxic analogues tested inhibited [3H]thymidine incorporation into DNA in cultures of human breast and prostate cancer cell lines

  9. 12-Amino-andrographolide analogues: synthesis and cytotoxic activity.

    PubMed

    Kasemsuk, Sakkasem; Sirion, Uthaiwan; Suksen, Kanoknetr; Piyachaturawat, Pawinee; Suksamrarn, Apichart; Saeeng, Rungnapha

    2013-12-01

    Andrographolide, a diterpenoid lactone of the plant Andrographis paniculata, has been shown to be cytotoxic against various cancer cells in vitro. In the present study, a series of β-amino-γ-butyrolactone analogues has been synthesized from naturally occurring andrographolide via one pot tandem aza-conjugate addition-elimination reaction. By using economic procedure without any base or catalyst at room temperature, the products obtained were in fair to excellent yields with high stereoselectivity. The cytotoxicity of all new amino analogues were evaluated against six cancer cell lines and revealed their potential for being developed as promising anti-cancer agents. PMID:23709127

  10. A New Alkylation-Elimination Method for Synthesis of Antiviral Fluoromethylenecyclopropane Analogues of Nucleosides

    PubMed Central

    Zhou, Shaoman; Zemlicka, Jiri

    2005-01-01

    A new method for the synthesis of fluoromethylenecyclopropane nucleosides by alkylation-elimination procedure is described. Fluorination of methylenecyclopropane carboxylate 6 gave fluoroester 7. Treatment of 7 with phenylselenenyl bromide afforded the desired ethyl (E)-2-bromomethyl-1-fluoro-2-phenylselenenylcyclopropane-1-carboxylate 11 in 85% yield. DIBALH reduction of 11 gave 13, which after acetylation to 14 was reacted with 2-amino-6-chloropurine to give the 9-alkylated product 15 in 87% yield. Se-oxydation of 15 with hydrogen peroxide afforded 16, which underwent smooth elimination in a mixture of THF-DMF at 60 °C giving rise to a Z,E mixture of protected nucleosides 17. Deacetylation gave Z-1a and E-1a which were separated on a silica gel column. Both Z-1a and E-1a were converted into the respective guanine analogues Z-1b and E-1b. PMID:16801980

  11. New cytotoxic analogues of annonaceous acetogenins.

    PubMed

    Rodier, S; Le Huerou, Y; Renoux, B; Doyon, J; Renard, P; Pierré, A; Gesson, J P; Grée, R

    2001-01-01

    A series of new acetogenin analogues incorporating a central catechol moiety instead of the tetrahydrofuran ring(s) have been prepared and tested against L1210 leukemia cells. Although less potent than bullatacinone, which has the same terminal lactone, these compounds display interesting cell cycle effects. PMID:11962508

  12. Effective strand invasion ODN incorporating a new bicyclic nucleoside analogue (WNA).

    PubMed

    Aoki, Eriko; Taniguchi, Yosuke; Sasaki, Shigeki

    2007-01-01

    Efficient and specific targeting of DNA sequences by synthetic ligands is a major goal in chemical biology. Triplex-forming oligonucleotides (TFOs) are sequence-specific DNA-binding agents, but are limited to homopurine/homopyrimidine target sequences. We have previously reported two useful analogues (WNA: W-shaped nucleoside analogues), WNA-bT and WNAbC, which recognize a TA and a CG interrupting site forming triplexes with high stability and selectivity, respectively. However, their ability to form triplexes depended on their neighbouring bases in the TFO. Subsequent studies have shown that the sequence-dependency of the WNA analogues, for the formation of triplexes, has been partially solved by use of a WNA analogue bearing a substituted aromatic ring. Investigations into the effects of the substituted aromatic ring of WNA derivatives on the stability of triplexes led to the discovery of strand invasion by the TFO incorporating the new WNA analogue to form a highly stable duplex. PMID:18029683

  13. Reactions of β-Propiolactone with Nucleobase Analogues, Nucleosides, and Peptides

    PubMed Central

    Uittenbogaard, Joost P.; Zomer, Bert; Hoogerhout, Peter; Metz, Bernard

    2011-01-01

    β-Propiolactone is often applied for inactivation of viruses and preparation of viral vaccines. However, the exact nature of the reactions of β-propiolactone with viral components is largely unknown. The purpose of the current study was to elucidate the chemical modifications occurring on nucleotides and amino acid residues caused by β-propiolactone. Therefore, a set of nucleobase analogues was treated with β-propiolactone, and reaction products were identified and quantified. NMR revealed at least one modification in either deoxyguanosine, deoxyadenosine, or cytidine after treatment with β-propiolactone. However, no reaction products were found from thymidine and uracil. The most reactive sides of the nucleobase analogues and nucleosides were identified by NMR. Furthermore, a series of synthetic peptides was used to determine the conversion of reactive amino acid residues by liquid chromatography-mass spectrometry. β-Propiolactone was shown to react with nine different amino acid residues. The most reactive residues are cysteine, methionine, and histidine and, to a lesser degree, aspartic acid, glutamic acid, tyrosine, lysine, serine, and threonine. Remarkably, cystine residues (disulfide groups) do not react with β-propiolactone. In addition, no reaction was observed for β-propiolactone with asparagine, glutamine, and tryptophan residues. β-Propiolactone modifies proteins to a larger extent than expected from current literature. In conclusion, the study determined the reactivity of β-propiolactone with nucleobase analogues, nucleosides, and amino acid residues and elucidated the chemical structures of the reaction products. The study provides detailed knowledge on the chemistry of β-propiolactone inactivation of viruses. PMID:21868382

  14. Synthesis and evaluation of thymidine kinase 1-targeting carboranyl pyrimidine nucleoside analogues for boron neutron capture therapy of cancer

    PubMed Central

    Agarwal, Hitesh K.; Khalil, Ahmed; Ishita, Keisuke; Yang, Weilian; Nakkula, Robin J.; Wu, Lai-Chu; Ali, Tehane; Tiwari, Rohit; Byun, Youngjoo; Barth, Rolf F.; Tjarks, Werner

    2015-01-01

    A library of sixteen 2nd generation amino- and amido-substituted carboranyl pyrimidine nucleoside analogues, designed as substrates and inhibitors of thymidine kinase 1 (TK1) for potential use in boron neutron capture therapy (BNCT) of cancer, was synthesized and evaluated in enzyme kinetic-, enzyme inhibition-, metabolomic-, and biodistribution studies. One of these 2nd generation carboranyl pyrimidine nucleoside analogues (YB18A [3]), having an amino group directly attached to a meta-carborane cage tethered via ethylene spacer to the 3-position of thymidine, was approximately 3–4 times superior as a substrate and inhibitor of hTK1 than N5-2OH (2), a 1st generation carboranyl pyrimidine nucleoside analogue. Both 2 and 3 appeared to be 5′-monophosphorylated in TK1(+) RG2 cells, both in vitro and in vivo. Biodistribution studies in rats bearing intracerebral RG2 glioma resulted in selective tumor uptake of 3 with an intratumoral concentration that was approximately 4 times higher than that of 2. The obtained results significantly advance the understanding of the binding interactions between TK1 and carboranyl pyrimidine nucleoside analogues and will profoundly impact future design strategies for these agents. PMID:26087030

  15. Four Generations of Transition State Analogues for Human Purine Nucleoside Phosphorylase

    SciTech Connect

    Ho, M.; Shi, W; Rinaldo-Mathis, A; Tyler, P; Evans, G; Almo, S; Schramm, V

    2010-01-01

    Inhibition of human purine nucleoside phosphorylase (PNP) stops growth of activated T-cells and the formation of 6-oxypurine bases, making it a target for leukemia, autoimmune disorders, and gout. Four generations of ribocation transition-state mimics bound to PNP are structurally characterized. Immucillin-H (K*{sub i} = 58 pM, first-generation) contains an iminoribitol cation with four asymmetric carbons. DADMe-Immucillin-H (K*{sub i} = 9 pM, second-generation), uses a methylene-bridged dihydroxypyrrolidine cation with two asymmetric centers. DATMe-Immucillin-H (K*{sub i} = 9 pM, third-generation) contains an open-chain amino alcohol cation with two asymmetric carbons. SerMe-ImmH (K*{sub i} = 5 pM, fourth-generation) uses achiral dihydroxyaminoalcohol seramide as the ribocation mimic. Crystal structures of PNPs establish features of tight binding to be; (1) ion-pair formation between bound phosphate (or its mimic) and inhibitor cation, (2) leaving-group interactions to N1, O6, and N7 of 9-deazahypoxanthine, (3) interaction between phosphate and inhibitor hydroxyl groups, and (4) His257 interacting with the 5{prime}-hydroxyl group. The first generation analogue is an imperfect fit to the catalytic site with a long ion pair distance between the iminoribitol and bound phosphate and weaker interactions to the leaving group. Increasing the ribocation to leaving-group distance in the second- to fourth-generation analogues provides powerful binding interactions and a facile synthetic route to powerful inhibitors. Despite chemical diversity in the four generations of transition-state analogues, the catalytic site geometry is almost the same for all analogues. Multiple solutions in transition-state analogue design are available to convert the energy of catalytic rate enhancement to binding energy in human PNP.

  16. Direct synthesis of imino-C-nucleoside analogues and other biologically active iminosugars

    PubMed Central

    Bergeron-Brlek, Milan; Meanwell, Michael; Britton, Robert

    2015-01-01

    Iminosugars have attracted increasing attention as chemical probes, chaperones and leads for drug discovery. Despite several clinical successes, their de novo synthesis remains a significant challenge that also limits their integration with modern high-throughput screening technologies. Herein, we describe a unique synthetic strategy that converts a wide range of acetaldehyde derivatives into iminosugars and imino-C-nucleoside analogues in two or three straightforward transformations. We also show that this strategy can be readily applied to the rapid production of indolizidine and pyrrolizidine iminosugars. The high levels of enantio- and diastereoselectivity, excellent overall yields, convenience and broad substrate scope make this an appealing process for diversity-oriented synthesis, and should enable drug discovery efforts. PMID:25903019

  17. New cembranolide analogues from the formosan soft coral Sinularia flexibilis and their cytotoxicity.

    PubMed

    Hsieh, Pei-Wen; Chang, Fang-Rong; McPhail, Andrew T; Lee, Kuo-Hsiung; Wu, Yang-Chang

    2003-12-01

    Using a bioactivity-guided fractionation procedure, five cembranolides, 11-epi-sinulariolide acetate (1), 11-dehydrosinulariolide (2), sinulariolide (3), dihydrosinularin (4), and 3,4:8,11-bisepoxy-7-acetoxycembra-15(17)-en-1,12-olide (5), along with two nucleosides, 2'-deoxyadenosine and thymidine, were isolated from the Formosan soft coral Sinularia flexibilis. Moreover, 7,8-epoxy-11-epi-sinulariolide acetate (1a), 11-sinulariolide acetate (3a), dihydrosinulariolide (3b), 3,4:8,11-bisepoxy-7-hydroxycembra-15(17)-en-1,12-olide (3c), 11-acetoxyl-15(17)-dihydrosinulariolide (3d), 7,8-epoxy-11-sinulariolide acetate (3e), and 3,4:8,11-bisepoxy-7-hydroxycembra-15(17)-dihydro-1,12-olide (3f) were derived from compounds 1 and 3, respectively. These structures were deduced on the basis of physical and chemical evidence. Among them, 1a, 3d, 3e, and 3f are new cembranolide analogues. The structure of compound 1 was further confirmed by X-ray analysis. In addition, the isolated cembranolides and the analogues under went a cytotoxicity assay, and the structure-activity relationship (SAR) of these compounds was studied. PMID:14577690

  18. Synthesis of purine and 7-deazapurine nucleoside analogues of 6-N-(4-Nitrobenzyl)adenosine; inhibition of nucleoside transport and proliferation of cancer cells.

    PubMed

    Rayala, Ramanjaneyulu; Theard, Patricia; Ortiz, Heysell; Yao, Sylvia; Young, James D; Balzarini, Jan; Robins, Morris J; Wnuk, Stanislaw F

    2014-09-01

    Human equilibrative nucleoside transporter 1 (hENT1) is a prototypical nucleoside transporter protein ubiquitously expressed on the cell surface of almost all human tissue. Given the role of hENT1 in the transport of nucleoside drugs, an important class of therapeutics in the treatment of various cancers and viral infections, efforts have been made to better understand the mechanisms by which hENT1 modulates nucleoside transport. To that end, we report here the design and synthesis of novel tool compounds for the further study of hENT1. The 7-deazapurine nucleoside antibiotic tubercidin was converted into its 4-N-benzyl and 4-N-(4-nitrobenzyl) derivatives by alkylation at N3 followed by a Dimroth rearrangement to the 4-N-isomer or by fluoro-diazotization followed by SN Ar displacement of the 4-fluoro group by a benzylamine. The 4-N-(4-nitrobenzyl) derivatives of sangivamycin and toyocamycin antibiotics were prepared by the alkylation approach. Cross-membrane transport of labeled uridine by hENT1 was inhibited to a weaker extent by the 4-nitrobenzylated tubercidin and sangivamycin analogues than was observed with 6-N-(4-nitrobenzyl)adenosine. Type-specific inhibition of cancer cell proliferation was observed at micromolar concentrations with the 4-N-(4-nitrobenzyl) derivatives of sangivamycin and toyocamycin, and also with 4-N-benzyltubercidin. Treatment of 2',3',5'-O-acetyladenosine with aryl isocyanates gave the 6-ureido derivatives but none of them exhibited inhibitory activity against cancer cell proliferation or hENT1. PMID:24788480

  19. A straightforward entry to chiral carbocyclic nucleoside analogues via the enantioselective [3+2] cycloaddition of α-nucleobase substituted acrylates.

    PubMed

    Xie, Ming-Sheng; Wang, Yong; Li, Jian-Ping; Du, Cong; Zhang, Yan-Yan; Hao, Er-Jun; Zhang, Yi-Ming; Qu, Gui-Rong; Guo, Hai-Ming

    2015-08-11

    A straightforward entry to chiral carbocyclic nucleoside analogues has been realized via the enantioselective [3+2] cycloaddition of α-nucleobase substituted acrylates to vinyl cyclopropanes for the first time. With Pd2(dba)3-L5 as the catalyst, carbocyclic purine, uracil, and thymine nucleoside analogues with quaternary stereocenters were obtained in excellent yields (up to 99% yield) and good enantioselectivities (up to 92% ee). PMID:26145719

  20. Synthesis and Cytotoxicity Studies of Titanocene C Analogues

    PubMed Central

    Hogan, Megan; Claffey, James; Fitzpatrick, Eoin; Hickey, Thomas; Pampillón, Clara; Tacke, Matthias

    2008-01-01

    From the carbolithiation of 6-N,N-dimethylamino fulvene (3) and 2,4[bis(N,N-dimethylamino)methyl]-N-methylpyrrolyl lithium (2a), N-(N′,N′-dimethylaminomethyl)benzimidazolyl lithium (2b), or p-(N,N-dimethylamino)methylphenyl lithium (2c), the corresponding lithium cyclopentadienide intermediate (4a–c) was formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl4' resulting in N,N-dimethylamino-functionalised titanocenes 5a–c. When these titanocenes were tested against a pig kidney epithelial cell line (LLC-PK), the IC50 values obtained were of 23, and 52  μM for titanocenes 5a and 5b, respectively. The most cytotoxic titanocene in this paper, 5c with an IC50 value of 13 μM, was found to be approximately two times less cytotoxic than its analogue Titanocene C (IC50=5.5 μM) and almost four times less cytotoxic than cisplatin, which showed an IC50 value of 3.3 μM when tested on the LLC-PK cell line. PMID:18274663

  1. Synthesis of 5′-Functionalized Nucleosides: S-Adenosylhomocysteine Analogues with the Carbon-5′ and Sulfur Atoms Replaced by a Vinyl or Halovinyl Unit

    PubMed Central

    Wnuk, Stanislaw F.; Sacasa, Pablo R.; Lewandowska, Elzbieta; Andrei, Daniela; Cai, Sumin; Borchardt, Ronald T.

    2008-01-01

    Adenosine and uridine analogues functionalized with alkenyl or fluoroalkenyl chain at C5′ were prepared employing cross-metathesis, Negishi couplings and Wittig reactions. Metathesis of the protected 5′-deoxy-5′-methyleneadenosine or uridine analogues with six-carbon amino acids (homoallylglycines) in the presence of Grubbs catalysts gave nucleoside analogues with the C5′-C6′ double bond. Alternatively, the Pd-catalyzed cross-coupling between the protected 5′-deoxy-5′-(iodomethylene) nucleosides and suitable alkylzinc bromides also provided analogues with alkenyl unit. Stereoselective Pd-catalyzed monoalkylation of 5′-(bromofluoromethylene)-5′-deoxyadenosine with alkylzinc bromides afforded adenosylhomocysteine analogues with a 6′-(fluoro)vinyl motif. The vinylic adenine nucleosides produced time-dependent inactivation of the S-adenosyl-L-homocysteine hydrolases. PMID:18457953

  2. Sinefungin, a Natural Nucleoside Analogue of S-Adenosylmethionine, Inhibits Streptococcus pneumoniae Biofilm Growth

    PubMed Central

    Park, Seok-Won; Chae, Sung-Won

    2014-01-01

    Pneumococcal colonization and disease is often associated with biofilm formation, in which the bacteria exhibit elevated resistance both to antibiotics and to host defense systems, often resulting in infections that are persistent and difficult to treat. We evaluated the effect of sinefungin, a nucleoside analogue of S-adenosylmethionine, on pneumococcal in vitro biofilm formation and in vivo colonization. Sinefungin is bacteriostatic to pneumococci and significantly decreased biofilm growth and inhibited proliferation and structure of actively growing biofilms but did not alter growth or the matrix structure of established biofilms. Sinefungin significantly reduced pneumococcal colonization in rat middle ear. The quorum sensing molecule (autoinducer-2) production was significantly reduced by 92% in sinefungin treated samples. The luxS, pfs, and speE genes were downregulated in biofilms grown in the presence of sinefungin. This study shows that sinefungin inhibits pneumococcal biofilm growth in vitro and colonization in vivo, decreases AI-2 production, and downregulates luxS, pfs, and speE gene expressions. Therefore, the S-adenosylmethionine (SAM) inhibitors could be used as lead compounds for the development of novel antibiofilm agents against pneumococci. PMID:25050323

  3. Dipeptidyl peptidase IV dependent water-soluble prodrugs of highly lipophilic bicyclic nucleoside analogues.

    PubMed

    Diez-Torrubia, Alberto; Balzarini, Jan; Andrei, Graciela; Snoeck, Robert; De Meester, Ingrid; Camarasa, María-José; Velázquez, Sonsoles

    2011-03-24

    We present the first report of the application of the dipeptidyl peptidase IV (DPPIV/CD26) based prodrug approach to hydroxy-containing drug derivatives. In particular, we applied this strategy to the highly lipophilic antiviral drug family of bicyclic furanopyrimidine nucleoside analogues (BCNA) in order to improve their physicochemical and pharmacokinetic properties. Our stability data demonstrated that the prodrugs efficiently release the parent BCNA drug upon selective conversion by purified DPPIV/CD26 and by soluble DPPIV/CD26 present in bovine, murine, and human serum. Vildagliptin, a specific inhibitor of DPPIV/CD26, was able to completely block the hydrolysis of the prodrugs in the presence of purified DPPIV/CD26 human, murine, and bovine serum. Several novel prodrugs showed remarkable increases in water solubility (up to more than 3 orders of magnitude) compared to the poorly soluble parent drug. We also demonstrated a markedly enhanced oral bioavailability of the prodrugs versus the parent drug in mice. PMID:21332170

  4. Aquaporin 3 (AQP3) participates in the cytotoxic response to nucleoside-derived drugs

    PubMed Central

    2012-01-01

    Background Nucleoside analogs used in the chemotherapy of solid tumors, such as the capecitabine catabolite 5′-deoxy-5-fluorouridine (5′-DFUR) trigger a transcriptomic response that involves the aquaglyceroporin aquaporin 3 along with other p53-dependent genes. Here, we examined whether up-regulation of aquaporin 3 (AQP3) mRNA in cancer cells treated with 5′-DFUR represents a collateral transcriptomic effect of the drug, or conversely, AQP3 participates in the activity of genotoxic agents. Methods The role of AQP3 in cell volume increase, cytotoxicity and cell cycle arrest was analyzed using loss-of-function approaches. Results 5′-DFUR and gemcitabine, but not cisplatin, stimulated AQP3 expression and cell volume, which was partially and significantly blocked by knockdown of AQP3. Moreover, AQP3 siRNA significantly blocked other effects of nucleoside analogs, including G1/S cell cycle arrest, p21 and FAS up-regulation, and cell growth inhibition. Short incubations with 5-fluorouracil (5-FU) also induced AQP3 expression and increased cell volume, and the inhibition of AQP3 expression significantly blocked growth inhibition triggered by this drug. To further establish whether AQP3 induction is related to cell cycle arrest and apoptosis, cells were exposed to long incubations with escalating doses of 5-FU. AQP3 was highly up-regulated at doses associated with cell cycle arrest, whereas at doses promoting apoptosis induction of AQP3 mRNA expression was reduced. Conclusions Based on the results, we propose that the aquaglyceroporin AQP3 is required for cytotoxic activity of 5’-DFUR and gemcitabine in the breast cancer cell line MCF7 and the colon adenocarcinoma cell line HT29, and is implicated in cell volume increase and cell cycle arrest. PMID:23017148

  5. Inhibition and structure of Trichomonas vaginalis purine nucleoside phosphorylase with picomolar transition state analogues.

    PubMed

    Rinaldo-Matthis, Agnes; Wing, Corin; Ghanem, Mahmoud; Deng, Hua; Wu, Peng; Gupta, Arti; Tyler, Peter C; Evans, Gary B; Furneaux, Richard H; Almo, Steven C; Wang, Ching C; Schramm, Vern L

    2007-01-23

    Trichomonas vaginalis is a parasitic protozoan purine auxotroph possessing a unique purine salvage pathway consisting of a bacterial type purine nucleoside phosphorylase (PNP) and a purine nucleoside kinase. Thus, T. vaginalis PNP (TvPNP) functions in the reverse direction relative to the PNPs in other organisms. Immucillin-A (ImmA) and DADMe-Immucillin-A (DADMe-ImmA) are transition state mimics of adenosine with geometric and electrostatic features that resemble early and late transition states of adenosine at the transition state stabilized by TvPNP. ImmA demonstrates slow-onset tight-binding inhibition with TvPNP, to give an equilibrium dissociation constant of 87 pM, an inhibitor release half-time of 17.2 min, and a Km/Kd ratio of 70,100. DADMe-ImmA resembles a late ribooxacarbenium ion transition state for TvPNP to give a dissociation constant of 30 pM, an inhibitor release half-time of 64 min, and a Km/Kd ratio of 203,300. The tight binding of DADMe-ImmA supports a late SN1 transition state. Despite their tight binding to TvPNP, ImmA and DADMe-ImmA are weak inhibitors of human and P. falciparum PNPs. The crystal structures of the TvPNP x ImmA x PO4 and TvPNP x DADMe-ImmA x PO4 ternary complexes differ from previous structures with substrate analogues. The tight binding with DADMe-ImmA is in part due to a 2.7 A ionic interaction between a PO4 oxygen and the N1' cation of the hydroxypyrrolidine and is weaker in the TvPNP x ImmA x PO4 structure at 3.5 A. However, the TvPNP x ImmA x PO4 structure includes hydrogen bonds between the 2'-hydroxyl and the protein that are not present in TvPNP x DADMe-ImmA x PO4. These structures explain why DADMe-ImmA binds tighter than ImmA. Immucillin-H is a 12 nM inhibitor of TvPNP but a 56 pM inhibitor of human PNP. And this difference is explained by isotope-edited difference infrared spectroscopy with [6-18O]ImmH to establish that O6 is the keto tautomer in TvPNP x ImmH x PO4, causing an unfavorable leaving-group interaction

  6. Short Communication: Transplacental Nucleoside Analogue Exposure and Mitochondrial Parameters in HIV-Uninfected Children

    PubMed Central

    Brogly, Susan B.; DiMauro, Salvatore; Van Dyke, Russell B.; Williams, Paige L.; Naini, Ali; Libutti, Daniel E.; Choi, Julia; Chung, Michelle

    2011-01-01

    Abstract Transplacental nucleoside analogue exposure can affect infant mitochondrial DNA (mtDNA). We evaluated mitochondria in peripheral blood mononuclear cells of children with and without clinical signs of mitochondrial dysfunction (MD) and antiretroviral (ARV) exposure. We previously identified 20 children with signs of MD (cases) among 1037 HIV-uninfected children born to HIV-infected women. We measured mtDNA copies/cell and oxidative phosphorylation (OXPHOS) NADH dehydrogenase (complex I) and cytochrome c oxidase (complex IV) protein levels and enzyme activities, determined mtDNA haplogroups and deletions in 18 of 20 cases with stored samples and in sex- and age-matched HIV-uninfected children, both ARV exposed and unexposed, (1) within 18 months of birth and (2) at the time of presentation of signs of MD. In specimens drawn within 18 months of birth, mtDNA levels were higher and OXPHOS protein levels and enzyme activities lower in cases than controls. In contrast, at the time of MD presentation, cases and ARV-exposed controls had lower mtDNA levels, 214 and 215 copies/cell, respectively, than ARV-unexposed controls, 254 copies/cell. OXPHOS protein levels and enzyme activities were lower in cases than exposed controls, and higher in cases than unexposed controls, except for complex IV activity, which was higher in cases. Haplotype H was less frequent among cases (6%) than controls (31%). No deletions were found. The long-term significance of these small but potentially important alterations should continue to be studied as these children enter adolescence and adulthood. PMID:21142587

  7. Functionalized Tricyclic Cytosine Analogues Provide Nucleoside Fluorophores with Improved Photophysical Properties and a Range of Solvent Sensitivities

    PubMed Central

    Rodgers, Brittney J.; Elsharif, Nada A.; Vashisht, Nisha; Mingus, Macy M.; Mulvahill, Mark A.; Stengel, Gudrun; Kuchta, Robert D.

    2014-01-01

    Tricyclic cytosines (tC and tCO frameworks) have emerged as a unique class of fluorescent nucleobase analogues that minimally perturb the structure of B-form DNA and that are not quenched in duplex nucleic acids. Systematic derivatization of these frameworks is a likely approach to improve on and diversify photophysical properties, but has not so far been examined. Synthetic methods were refined to improve on tolerance for electron donating and electron withdrawing groups, resulting in a series of eight new, fluorescent cytidine analogues. Photophysical studies show that substitution of the framework results in a pattern of effects largely consistent across tC and tCO and provides nucleoside fluorophores that are brighter than either parent. Moreover, a range of solvent sensitivities is observed, offering promise that this family of probes can be extended to new applications that require reporting on the local environment. PMID:24311229

  8. Cytotoxic and antibacterial activities of the analogues of pogostone.

    PubMed

    Tang, Zheng-Wei; Peng, Cheng; Dai, Min; Han, Bo

    2015-10-01

    Six new (A5-A6, A8-A11) and six known (A1-A4, A7, PO) α-pyrone compounds were synthesized with dehydroacetate and aldehydes in tetrahydrofuran at room temperature. And their structures were determined by (1)H-NMR, (13)C-NMR and mass spectroscopy. In the bioscreening experiments, ten compounds (A1-A5, PO, A7-A10) exhibited antibacterial activities against Staphylococcus aureus ATCC 25923 with minimum inhibitory concentration (MIC) values of 4-512 mg/L, and nine compounds (A1-A5, PO, A7-A8, A10) exhibited antibacterial activities against Methicillin-resistant S. aureus (MRSA) ATCC 43300 with MIC values of 4-256 mg/L. Moreover, compound A10 showed the highest antibacterial activity against S. aureus ATCC 25923 and MRSA with MIC values of 4 mg/L, while the MIC values of Amoxicillin were 8 mg/L and >256 mg/L, respectively. Two compounds (A8 and PO) exhibited antibacterial activities against Escherichia coli ATCC 25922 with MIC values of 32-512 mg/L. However, only one compound (A8) exhibited significant antibacterial activity against Pseudomonas aeruginosa CVCC 3360 with MIC value of 256 mg/L. Moreover, A10 exhibited significant inhibition of proliferation in the four cell lines MCF-10, A549, A2780 and MFC, and showed stronger inhibitive activity of these four selected cell lines than cisplatin in the cytotoxic assay. Thus, this study suggests that pogostone analogues, especially A10, represented a kind of promising antibacterial and antineoplastic agents. PMID:26272659

  9. Conformational analysis of a nucleoside of 1,4-dihydro-4-oxoquinoline-3-carboxylic acid analogue

    NASA Astrophysics Data System (ADS)

    Zaccur Leal, Kátia; Rudolf Seidl, Peter; Diniz Yoneda, Julliane; Santos, CarlaV. B.; Marques, Isakelly P.; Souza, Maria Cecília B. V.; Francisco Ferreira, Vitor

    2005-06-01

    The synthesis of new ribonucleosides is an essential research area in the investigation of new therapeutically useful agents, particularly those used in the treatment of HIV infection. The conformation of these nucleosides may have direct implications for their ability to bind to receptor targets. We have prepared the 7-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylic acid derivatives and used the ensemble of low-energy minima to develop conformational profiles of quinolonic nucleosides and verify their accuracy in different calculations of structural parameters. Results are compared with experimental data obtained by X-ray and NMR analysis. Finally, we intend to test the applicability of these methods to conformational analysis of other nucleosides and verify if the preferential conformation is the one which gives the best anti-HIV or antiviral activity.

  10. Synthesis, antiviral activity, cytotoxicity and cellular pharmacology of l-3'-azido-2',3'-dideoxypurine nucleosides.

    PubMed

    Zhang, Hong-Wang; Detorio, Mervi; Herman, Brian D; Solomon, Sarah; Bassit, Leda; Nettles, James H; Obikhod, Aleksandr; Tao, Si-Jia; Mellors, John W; Sluis-Cremer, Nicolas; Coats, Steven J; Schinazi, Raymond F

    2011-09-01

    Microwave-assisted optimized transglycosylation reactions were used to prepare eleven modified l-3'-azido-2',3'-dideoxypurine nucleosides. These l-nucleoside analogs were evaluated against HIV and hepatitis B virus. The l-3'-azido-2',3'-dideoxypurines nucleosides were metabolized to nucleoside 5'-triphosphates in primary human lymphocytes, but exhibited weak or no antiviral activity against HIV-1. The nucleosides were also inactive against HBV in HepG2 cells. Pre-steady state kinetic experiments demonstrated that the l-3'-azido-2',3'-dideoxypurine triphosphates could be incorporated by purified HIV-1 reverse transcriptase, although their catalytic efficiency (k(pol)/K(d)) of incorporation was low. Interestingly, a phosphoramidate prodrug of l-3'-azido-2',3'-dideoxyadenosine exhibited anti-HIV-1 activity without significant toxicity. PMID:21700368

  11. Synthesis of Purine and 7-Deazapurine Nucleoside Analogues of 6-N-(4-Nitrobenzyl)adenosine; Inhibition of Nucleoside Transport and Proliferation of Cancer Cells

    PubMed Central

    Rayala, Ramanjaneyulu; Theard, Patricia; Ortiz, Heysell; Yao, Sylvia; Young, James D.; Balzarini, Jan; Robins, Morris J.

    2014-01-01

    The 7-deazapurine nucleoside antibiotic tubercidin was converted into its 4-N-benzyl and 4-N-(4-nitrobenzyl) derivatives by alkylation at N3 followed by Dimroth rearrangement to the 4-N- isomer or by fluoro-diazotization followed by SNAr displacement of the 4-fluoro group by a benzylamine. The 4-N-(4-nitrobenzyl) derivatives of sangivamycin and toyocamycin antibiotics were prepared by the alkylation approach. Cross-membrane transport of labeled uridine by hENT1 was inhibited to a weaker extent by the 4-nitrobenzylated tubercidin and sangivamycin analogues than was observed with 6-N-(4-nitrobenzyl)adenosine. Type-specific inhibition of cancer cell proliferation was observed at μM concentrations with the 4-N-(4-nitrobenzyl) derivatives of sangivamycin and toyocamycin, and also with 4-N-benzyltubercidin. Treatment of 2′,3′,5′-O-acetyladenosine with aryl isocyanates gave the 6-ureido derivatives but none of them exhibited inhibitory activity against cancer cell proliferation or hENT1. PMID:24788480

  12. Cytotoxic Evaluation against Breast Cancer Cells of Isoliquiritigenin Analogues from Spatholobus suberectus and Their Synthetic Derivatives.

    PubMed

    Peng, Fu; Meng, Chun-Wang; Zhou, Qin-Mei; Chen, Jian-Ping; Xiong, Liang

    2016-01-22

    Five isoliquiritigenin analogues, including a new methylene-bridged bischalcone (1), were isolated from Spatholobus suberectus. Cytotoxicity screening of these isolates and several synthetic derivatives indicated that the introduction, removal, position modification, or glycosylation of hydroxy groups in isoliquiritigenin did not improve the resultant cytotoxicity against the MCF-7 and MDA-MB-231 human breast cancer cell lines. In addition, cyclization of OH-2' chalcones or reduction of the α,β-unsaturated carbonyl double bond decreased such cytotoxicity substantially. However, methylation of hydroxy groups resulted in a marked increase in such cytotoxic activity. Among these active isoliquiritigenin analogues, 3',4',5',4″-tetramethoxychalcone (3h) was obtained as a compound with promising cytotoxic activity. PMID:26690274

  13. Synthesis, cytotoxicity and inhibition of NO production of ivangustin enantiomer analogues.

    PubMed

    Qin, Xiang-Yang; Chen, Bing-Yang; Fu, Jian-Jun; Shan, Lei; Lei, Xiao-Guang; Zhang, Wei-Dong

    2015-09-18

    The eight novel ivangustin enantiomer analogues possessing α-methylene-γ-butyrolactone moiety have been synthesized using (4S6R, 4S6S)-4-tert-butyldimethylsilyloxy-6-methylcyclohex-2-en-1-one (1) as starting material. These transformations were mainly carried out by aldol condensation reaction and one-pot annelation procedure. The stereochemistry of these synthesized analogues was determined by NOE analysis. Their cytoxicity was evaluated against the human cancer cell lines HCT-116 (colon), HL-60 (leukemia), QGY-7701 (liver), SMMC-7721 (liver), A549 (lung), MCF-7 (breast). The results showed that these analogues were more selective against the cell lines HL-60 and QGY-7701. Analogue 17 exhibited potent cytotoxicity and high selectivity toward HL-60 cell line with IC50 value of 1.02 μM, which suggested that it might be a promising anti-cancer lead compound. The inhibitory activities against NO production and the cytotoxicities in RAW 264.7 macrophages were determined at the same time. All of the analogues significantly inhibited the NO production with IC50 value in the range of 3.44-6.99 μM. Analogues 17, 22, 23 and 7 showed higher cytotoxicities, indicated their inhibitory activities against NO production may be influenced by the cytotoxicities. PMID:26280922

  14. Application of germyldesulfonylation reactions to the synthesis of germanium-containing nucleoside analogues.

    PubMed

    Wnuk, Stanislaw F; Sacasa, Pablo R; Restrepo, Jorge

    2009-05-01

    Treatment of the protected (E)-5'-deoxy-5'-[(p-toluenesulfonyl)methylene]uridine and adenosine derivatives with tributyl- or triphenylgermane hydride (AIBN/toluene/Delta) effected radical-mediated germyldesulfonylations to give 5'-(tributyl- or triphenylgermyl)methylene-5'-deoxyuridine and adenosine derivatives as single (E)-isomers. Analogous treatment of 2'-deoxy-2'-[(phenylsulfonyl)methylene]uridine with Ph(3)GeH afforded the corresponding vinyl triphenylgermane product. Stereoselective halodegermylation of the (E)-5'-(tributylgermyl)methylene-5'-deoxy nucleosides with N-iodosuccinimide or N-bromosuccinimide provided the Wittig-type (E)-5'-deoxy-5'-(halomethylene) nucleosides quantitatively, while no halodegermylations was observed with the 5'-deoxy-5'-(triphenylgermyl)methylene counterparts. Treatment of the vinyl trialkylgermanes with aqueous trifluoroacetic acid effected protiodegermylation, while vinyl triarylgermanes were stable under the acidic conditions. PMID:20183601

  15. [Luliberin analogues exhibiting a cytotoxic effect on tumor cells in vitro].

    PubMed

    Burov, S V; Iablokova, T V; Dorosh, M Iu; Shkarubskaia, Z P; Blank, M; Epshteĭn, N; Fridkin, M

    2006-01-01

    Luliberin analogues modified at the N-terminus were synthesized to search for drugs exerting a cytotoxic effect on cells of hormone-dependent tumors. A synthetic scheme effective in the preparation of analogues containing fatty acid residues was proposed. The cytotoxic effect of the peptides was studied on a number of cell lines of human tumors in vitro. The dependence of the antitumor effect on the length of peptide chain, amino acid sequence, and structure of the N-terminal group was demonstrated. Modification with palmitic acid was found to result in highly active compounds in the case of analogues containing more than ten aa, whereas modifications with lauric, caproic, or trimethylacetic acid led to compounds with significantly lower activities. Analogues of luliberin containing a palmitic acid residue and effectively inhibiting the growth of tumor cells in vitro were synthesized. PMID:17042263

  16. Integrative Gene Expression Profiling Reveals G6PD-Mediated Resistance to RNA-Directed Nucleoside Analogues in B-Cell Neoplasms

    PubMed Central

    McBrayer, Samuel K.; Yarrington, Michael; Qian, Jun; Feng, Gang; Shanmugam, Mala; Gandhi, Varsha; Krett, Nancy L.; Rosen, Steven T.

    2012-01-01

    The nucleoside analogues 8-amino-adenosine and 8-chloro-adenosine have been investigated in the context of B-lineage lymphoid malignancies by our laboratories due to the selective cytotoxicity they exhibit toward multiple myeloma (MM), chronic lymphocytic leukemia (CLL), and mantle cell lymphoma (MCL) cell lines and primary cells. Encouraging pharmacokinetic and pharmacodynamic properties of 8-chloro-adenosine being documented in an ongoing Phase I trial in CLL provide additional impetus for the study of these promising drugs. In order to foster a deeper understanding of the commonalities between their mechanisms of action and gain insight into specific patient cohorts positioned to achieve maximal benefit from treatment, we devised a novel two-tiered chemoinformatic screen to identify molecular determinants of responsiveness to these compounds. This screen entailed: 1) the elucidation of gene expression patterns highly associated with the anti-tumor activity of 8-chloro-adenosine in the NCI-60 cell line panel, 2) characterization of altered transcript abundances between paired MM and MCL cell lines exhibiting differential susceptibility to 8-amino-adenosine, and 3) integration of the resulting datasets. This approach generated a signature of seven unique genes including G6PD which encodes the rate-determining enzyme of the pentose phosphate pathway (PPP), glucose-6-phosphate dehydrogenase. Bioinformatic analysis of primary cell gene expression data demonstrated that G6PD is frequently overexpressed in MM and CLL, highlighting the potential clinical implications of this finding. Utilizing the paired sensitive and resistant MM and MCL cell lines as a model system, we go on to demonstrate through loss-of-function and gain-of-function studies that elevated G6PD expression is necessary to maintain resistance to 8-amino- and 8-chloro-adenosine but insufficient to induce de novo resistance in sensitive cells. Taken together, these results indicate that G6PD activity

  17. Conformation-sensitive nucleoside analogues as topology-specific fluorescence turn-on probes for DNA and RNA G-quadruplexes

    PubMed Central

    Tanpure, Arun A.; Srivatsan, Seergazhi G.

    2015-01-01

    Development of probes that can discriminate G-quadruplex (GQ) structures and indentify efficient GQ binders on the basis of topology and nucleic acid type is highly desired to advance GQ-directed therapeutic strategies. In this context, we describe the development of minimally perturbing and environment-sensitive pyrimidine nucleoside analogues, based on a 5-(benzofuran-2-yl)uracil core, as topology-specific fluorescence turn-on probes for human telomeric DNA and RNA GQs. The pyrimidine residues of one of the loop regions (TTA) of telomeric DNA and RNA GQ oligonucleotide (ON) sequences were replaced with 5-benzofuran-modified 2′-deoxyuridine and uridine analogues. Depending on the position of modification the fluorescent nucleoside analogues distinguish antiparallel, mixed parallel-antiparallel and parallel stranded DNA and RNA GQ topologies from corresponding duplexes with significant enhancement in fluorescence intensity and quantum yield. Further, these GQ sensors enabled the development of a simple fluorescence binding assay to quantify topology- and nucleic acid-specific binding of small molecule ligands to GQ structures. Together, our results demonstrate that these nucleoside analogues are useful GQ probes, which are anticipated to provide new opportunities to study and discover efficient G-quadruplex binders of therapeutic potential. PMID:26202965

  18. Synthesis, DNA-damaging and cytotoxic properties of novel topoisomerase II-directed bisantrene analogues.

    PubMed

    Zagotto, G; Oliva, A; Guano, F; Menta, E; Capranico, G; Palumbo, M

    1998-01-20

    New bisantrene analogues were synthesized, bearing one or two 4,5-dihydro-1H-imidazol-2-yl hydrazone side chains at positions 1,4 or 9 of the anthracene ring system. A 10-azabioisostere was also prepared. The position of substituents in structurally isomeric drugs modulates topoisomerase II poisoning and specificity, along with cytotoxicity. PMID:9871638

  19. Paper Synthesis, Cytotoxicity and Apoptosis Induction in Human Tumor Cells by Galaxamide and Its Analogues

    PubMed Central

    Xiao, Xi; Liao, Xiaojian; Qiu, Shaoling; Liu, Zihao; Du, Bin; Xu, Shihai

    2014-01-01

    Our previous study reported that galaxamide, which is a cyclo-pentapeptide containing five leucines that was extracted from Galaxaura filamentosa, displayed remarkable anticancer cytotoxicity. This novel cyclo-peptide provided a new skeleton for the structural modifications used in finding new drugs with better anticancer properties. In this study, five analogues were synthesized based on changing the number of d/l amino acids by adding a new amino acid, phenylalanine. Galaxamide and five of its analogues were evaluated through MTT assays to examine their cytotoxic activities. We found that modified analogue 5, which is referred to as A5, displayed broad spectrum cytotoxic activity toward every cell line tested; in addition, the IC50 of A5 was lower than that of galaxamide and the other analogues. Furthermore, we used flow cytometry and western blot assays to investigate whether galaxamide and A5 could induce cancer cell apoptosis. The flow cytometric studies showed that HepG2 cells treated with different concentrations of galaxamide or A5 over 72 h displayed significant and dose-dependent increases in the percentages of early-stage apoptotic cells. Western blotting revealed that both compounds induce caspase-dependent apoptosis in HepG2 cells through a mitochondria-mediated pathway. The results demonstrate that galaxamide and its analogues have potential applications as clinical anticancer drugs. PMID:25231922

  20. Establishment of new transmissible and drug-sensitive human immunodeficiency virus type 1 wild types due to transmission of nucleoside analogue-resistant virus.

    PubMed

    de Ronde, A; van Dooren, M; van Der Hoek, L; Bouwhuis, D; de Rooij, E; van Gemen, B; de Boer, R; Goudsmit, J

    2001-01-01

    Sequence analysis of human immunodeficiency virus type 1 (HIV-1) from 74 persons with acute infections identified eight strains with mutations in the reverse transcriptase (RT) gene at positions 41, 67, 68, 70, 215, and 219 associated with resistance to the nucleoside analogue zidovudine (AZT). Follow-up of the fate of these resistant HIV-1 strains in four newly infected individuals revealed that they were readily replaced by sensitive strains. The RT of the resistant viruses changed at amino acid 215 from tyrosine (Y) to aspartic acid (D) or serine (S), with asparagine (N) as a transient intermediate, indicating the establishment of new wild types. When we introduced these mutations and the original threonine (T)-containing wild type into infectious molecular clones and assessed their competitive advantage in vitro, the order of fitness was in accord with the in vivo observations: 215Y < 215D = 215S = 215T. As detected by real-time nucleic acid sequence-based amplification with two molecular beacons, the addition of AZT or stavudine (d4T) to the viral cultures favored the 215Y mutant in a dose-dependent manner. Our results illustrate that infection with nucleoside analogue-resistant HIV leads in newly infected individuals to mutants that are sensitive to nucleoside analogues, but only a single mutation removed from drug-resistant HIV. Such mutants were shown to be transmissible, stable, and prone to rapid selection for resistance to AZT or d4T as soon as antiretroviral therapy was administered. Monitoring of patients for the presence of new HIV-1 wild types with D, S, or N residues at position 215 may be warranted in order to estimate the threat to long-term efficacy of regimens including nucleoside analogues. PMID:11134272

  1. Synthesis and Anti-Influenza Activity of Pyridine, Pyridazine, and Pyrimidine C-Nucleosides as Favipiravir (T-705) Analogues.

    PubMed

    Wang, Guangyi; Wan, Jinqiao; Hu, Yujian; Wu, Xiangyang; Prhavc, Marija; Dyatkina, Natalia; Rajwanshi, Vivek K; Smith, David B; Jekle, Andreas; Kinkade, April; Symons, Julian A; Jin, Zhinan; Deval, Jerome; Zhang, Qingling; Tam, Yuen; Chanda, Sushmita; Blatt, Lawrence; Beigelman, Leonid

    2016-05-26

    Influenza viruses are responsible for seasonal epidemics and occasional pandemics which cause significant morbidity and mortality. Despite available vaccines, only partial protection is achieved. Currently, there are two classes of widely approved anti-influenza drugs: M2 ion channel blockers and neuraminidase inhibitors. However, the worldwide spread of drug-resistant influenza strains poses an urgent need for novel antiviral drugs, particularly with a different mechanism of action. Favipiravir (T-705), a broad-spectrum antiviral agent, has shown potent anti-influenza activity in cell-based assays, and its riboside (2) triphosphate inhibited influenza polymerase. In one of our approaches to treat influenza infection, we designed, prepared, and tested a series of C-nucleoside analogues, which have an analogy to 2 and were expected to act by a similar antiviral mechanism as favipiravir. Compound 3c of this report exhibited potent inhibition of influenza virus replication in MDCK cells, and its triphosphate was a substrate of and demonstrated inhibitory activity against influenza A polymerase. Metabolites of 3c are also presented. PMID:27120583

  2. Inhibition and Structure of Trichomonas vaginalis Purine Nucleoside Phosphorylase with Picomolar Transition State Analogues

    SciTech Connect

    Rinaldo-Matthis,A.; Wing, C.; Ghanem, M.; Deng, H.; Wu, P.; Gupta, A.; Tyler, P.; Evans, G.; Furneaux, R.; et al.

    2007-01-01

    Trichomonas vaginalis is a parasitic protozoan purine auxotroph possessing a unique purine salvage pathway consisting of a bacterial type purine nucleoside phosphorylase (PNP) and a purine nucleoside kinase. Thus, T. vaginalis PNP (TvPNP) functions in the reverse direction relative to the PNPs in other organisms. Immucillin-A (ImmA) and DADMe-Immucillin-A (DADMe-ImmA) are transition stte mimics of adenosine with geometric and electrostatic features that resemble early and late transition states of adenosine at the transition state stabilized by TvPNP. ImmA demonstrates slow-onset tight-binding inhibition with TvPNP, to give an equilibrium dissociation constant of 87 pM, an inhibitor release half-time of 17.2 min, and a K{sub m}/K{sub d} ratio of 70,100. DADMe-ImmA resembles a late ribooxacarbenium ion transition state for TvPNP to give a dissociation constant of 30 pM, an inhibitor release half-time of 64 min, and a K{sub m}/K{sub d} ratio of 203,300. The tight binding of DADMe-ImmA supports a late S{sub N}1 transition state. Despite their tight binding to TvPNP, ImmA and DADMe-ImmA are weak inhibitors of human and P. falciparum PNPs. The crystal structures of the TvPNP-ImmA{center_dot}PO{sub 4} and TvPNP{center_dot}DADMe-ImmA{center_dot}PO{sub 4} ternary complexes differ from previous structures with substrate anologues. The tight binding with DADMe-ImmA is in part due to a 2.7 {angstrom} ionic interaction between a PO{sub 4} oxygen and the N1 cation of the hydroxypyrrolidine and is weaker in the TvPNP{center_dot}ImmA{center_dot}PO{sub 4} structure at 3.5 {angstrom}. However, the TvPNP{center_dot}ImmA{center_dot}PO{sub 4} structure includes hydrogen bonds between the 2'-hydroxyl and the protein that are not present in TvPNP{center_dot}DADMe-ImmA{center_dot}PO{sub 4}. These structures explain why DADMe-ImmA binds tighter than ImmA. Immucillin-H is a 12 nM inhibitor of TvPNP but a 56 pM inhibitor of human PNP. And this difference is explained by isotope

  3. Nucleoside-5'-phosphorothioate analogues are biocompatible antioxidants dissolving efficiently amyloid beta-metal ion aggregates.

    PubMed

    Amir, Aviran; Shmuel, Eran; Zagalsky, Rostislav; Sayer, Alon H; Nadel, Yael; Fischer, Bilha

    2012-07-28

    Amyloid beta (Aβ) peptide is known to precipitate and form aggregates with zinc and copper ions in vitro and, in vivo in Alzheimer's disease (AD) patients. Metal-ion-chelation was suggested as therapy for the metal-ion-induced Aβ aggregation, metal-ion overload, and oxidative stress. In a quest for biocompatible metal-ion chelators potentially useful for AD therapy, we tested a series of nucleoside 5'-phosphorothioate derivatives as re-solubilization agents of Cu(+)/Cu(2+)/Zn(2+)-induced Aβ-aggregates, and inhibitors of Fenton reaction in Cu(+) or Fe(2+)/H(2)O(2) system. The most promising chelator in this series was found to be APCPP-γ-S. This nucleotide was found to be more efficient than EDTA in re-solubilization of Aβ(40)-Cu(2+) aggregates as observed by the lower diameter, d(H), (86 vs. 64 nm, respectively) obtained in dynamic light scattering measurements. Likewise, APCPP-γ-S dissolved Aβ(40)-Cu(+) and Aβ(42)-Cu(2+)/Zn(2+) aggregates, as monitored by (1)H-NMR and turbidity assays, respectively. Furthermore, addition of APCPP-γ-S to nine-day old Aβ(40)-Cu(2+)/Zn(2+) aggregates, resulted in size reduction as observed by transition electron microscopy (diameter reduction from 2.5 to 0.1 μm for Aβ(40)-Cu(2+) aggregates). APCPP-γ-S proved to be more efficient than ascorbic acid and GSH in reducing OH radical production in Fe(2+)/H(2)O(2) system (IC(50) values 85, 216 and, 92 μM, respectively). Therefore, we propose APCPP-γ-S as a potential AD therapy capable of both reducing OH radical production and re-solubilization of Aβ(40/42)-M(n+) aggregates. PMID:22652964

  4. Effects of four nucleoside analogues used as antiviral agents on rat Sertoli cells (SerW3) in vitro.

    PubMed

    Qiu, Runan; Horvath, Aniko; Stahlmann, Ralf

    2016-08-01

    Some nucleoside analogues are used to treat herpes simplex and other viral infections. They are known to impair spermatogenesis, but published data are scarce. We studied the effects of four nucleosides on SerW3 cells, a rat Sertoli cell line. Cells were cultured for 3 days in DMEM supplemented with four different concentrations of each drug. Aciclovir and ganciclovir were added at concentrations of 0.3, 1, 3 and 10 mg/l medium; penciclovir and its prodrug famciclovir were used at higher concentrations (3, 10, 30, 100 mg/l medium). After a culture period of 3 days, we analysed the expression of connexin43, N-cadherin and the cytoskeleton protein vimentin by Western blot. Aciclovir caused a clear-cut effect at the highest concentration tested (10 mg/l), which is less than the peak plasma concentration achieved in patients during intravenous therapy with the drug. Connexin43, vimentin and N-cadherin content decreased to 49.8 ± 17, 44.0 ± 4 and 75.4 ± 1.5 % of the control values, respectively (n = 3; mean ± SD). Similar effects were observed with the prodrug ganciclovir (43.2 ± 10.8; 54.1 ± 11.9; 84.4 ± 10.8 % of controls). Penciclovir caused less pronounced effects at 10 mg/l medium (82.1 ± 20.6; 90.0 ± 12.0; 76.5 ± 17.7 % of controls). Only a slight effect was observed with famciclovir. Even at a 10-fold concentration (100 mg/l), just moderate changes were induced. In summary, we observed clear-cut effects with aciclovir and ganciclovir on Sertoli cells in vitro at therapeutically relevant concentrations and identified connexin43 as the most sensitive marker. PMID:27224990

  5. Indomethacin Analogues that Enhance Doxorubicin Cytotoxicity in Multidrug Resistant Cells without Cox Inhibitory Activity.

    PubMed

    Arisawa, Mitsuhiro; Kasaya, Yayoi; Obata, Tohru; Sasaki, Takuma; Ito, Mika; Abe, Hiroshi; Ito, Yoshihiro; Yamano, Akihito; Shuto, Satoshi

    2011-05-12

    Conformationally restricted indomethacin analogues were designed and prepared from the corresponding 2-substituted indoles, which were synthesized by a one-pot isomerization/enamide-ene metathesis as the key reaction. Conformational analysis by calculations, NMR studies, and X-ray crystallography suggested that these analogues were conformationally restricted in the s-cis or the s-trans form due to the 2-substituent as expected. Their biological activities on cyclooxygenase-1 (COX-1) inhibition, cyclooxygenase-2 (COX-2) inhibition, and modulation of MRP-1-mediated multidrug resistance (MDR) are described. Some of these indomethacin analogues enhanced doxorubicin cytotoxicity, although they do not have any COX inhibitory activity, which suggests that the MDR-modulating effect of an NSAID can be unassociated with its COX-inhibitory activity. This may be an entry into the combination chemotherapy of doxorubicin with a MDR modulator. PMID:24900317

  6. Design, structure activity relationship, cytotoxicity and evaluation of antioxidant activity of curcumin derivatives/analogues.

    PubMed

    Sahu, Pramod K

    2016-10-01

    New fourteen 3,4-dihydropyrimidine derivatives/analogues of curcumin (2a-2n) were designed, synthesized and biologically evaluated for their cytotoxicity and antioxidant activity. Cytotoxicity effect has been evaluated against three cell lines HeLa, HCT-116 and QG-56 by MTT assay method. From SAR study, it has been revealed that particularly, compound 2e and 2j (IC50 value 12.5 μM) have shown better cytotoxicity effect against three cell lines. According to results of SAR study, it was found that 3,4-dihydropyrimidines of curcumin, 2c, 2d, 2j and 2n exhibited better antioxidant activity than curcumin. A correlation of structure and activities relationship of these compounds with respect to drug score profiles and other physico-chemical properties of drugs are described and verified experimentally. Therefore, we conclude that physico-chemical analyses may prove structural features of curcumin analogues with their promising combined cytotoxicity/antioxidant activity and it is also concluded from virtual and practical screening that the compounds were varied to possess a broad range of lipophilic character, revealed by Log P values. PMID:27318975

  7. Inhibition of Homologous Recombination and Promotion of Mutagenic Repair of DNA Double-Strand Breaks Underpins Arabinoside-Nucleoside Analogue Radiosensitization.

    PubMed

    Magin, Simon; Papaioannou, Maria; Saha, Janapriya; Staudt, Christian; Iliakis, George

    2015-06-01

    In concurrent chemoradiotherapy, drugs are used to sensitize tumors to ionizing radiation. Although a spectrum of indications for simultaneous treatment with drugs and radiation has been defined, the molecular mechanisms underpinning tumor radiosensitization remain incompletely characterized for several such combinations. Here, we investigate the mechanisms of radiosensitization by the arabinoside nucleoside analogue 9-β-D-arabinofuranosyladenine (araA) placing particular emphasis on the repair of DNA double-strand breaks (DSB), and compare the results to those obtained with fludarabine (F-araA) and cytarabine (araC). Postirradiation treatment with araA strongly sensitizes cells to ionizing radiation, but leaves unchanged DSB repair by NHEJ in logarithmically growing cells, in sorted G1 or G2 phase populations, as well as in cells in the plateau phase of growth. Notably, araA strongly inhibits DSB repair by homologous recombination (HRR), as assessed by scoring ionizing radiation-induced RAD51 foci, and in functional assays using integrated reporter constructs. Cells compromised in HRR by RNAi-mediated transient knockdown of RAD51 show markedly reduced radiosensitization after treatment with araA. Remarkably, mutagenic DSB repair compensates for HRR inhibition in araA-treated cells. Compared with araA, F-araA and araC are only modestly radiosensitizing under the conditions examined. We propose that the radiosensitizing potential of nucleoside analogues is linked to their ability to inhibit HRR and concomitantly promote the error-prone processing of DSBs. Our observations pave the way to treatment strategies harnessing the selective inhibitory potential of nucleoside analogues and the development of novel compounds specifically utilizing HRR inhibition as a means of tumor cell radiosensitization. PMID:25840584

  8. Antiviral therapy with nucleotide/nucleoside analogues in chronic hepatitis B: A meta-analysis of prospective randomized trials.

    PubMed

    Bedre, Renesh H; Raj, Utkarsh; Misra, Sri Prakash; Varadwaj, Pritish Kumar

    2016-03-01

    Nucleotide/nucleoside analogues (antiviral therapy) are used in the therapy of HBeAg positive and HBeAg negative chronic hepatitis B. We analyzed ten selected randomized controlled with 2557 patients to estimate the effect of antiviral drugs in chronic hepatitis B with compared to placebo. Virological response, biochemical response, histological response, seroconversion of HBeAg, and loss of HBeAg were estimated as primary efficacy measures. The included studies were subjected for heterogeneity and publication bias. The heterogeneity was assessed with χ2 and I(2) statistics. Publication bias was assessed by funnel plot. Greater rates of improvement obtained in antiviral group for virological response [43.96 % vs. 3.15 %, RR = 0.57, 95 % CI = 0.54-0.61, p-value <0.00001], biochemical response [58.37 % vs. 21.87 %, RR = 0.52, 95 % CI = 0.48-0.56, p-value <0.00001], histological response [58.99 % vs. 27.13 %, RR = 0.56, 95 % CI = 0.50-0.63, p-value <0.0001], seroconversion of HBeAg [10.66 % vs. 5.56 %, RR = 0.94, 95 % CI = 0.91-0.97, p-value = 0.0005], and HBeAg loss [14.59 % vs. 9.64 %, RR = 0.92, 95 % CI = 0.88-0.96, p-value = 0.0002]. The safety analysis were carried out for adverse events such as headache [17.22 % vs. 17.34 %, OR = 1.09, 95 % CI = 0.81-1.46, p-value = 0.58], abdominal pain [16.46 % vs. 14.34 %, OR = 1.24, 95 % CI = 0.90-1.72, p-value = 0.19], and pharyngitis [22.22 % vs. 18.23 %, OR = 1.12, 95 % CI = 0.86-1.45, p-value = 0.40]. Excluding adverse events, all primary efficacy measures shown statistical significant result for chronic hepatitis treatment (p-value <0.05). Antiviral therapy provided significant benefit for the treatment of chronic hepatitis B with no measurable adverse effects. PMID:27083430

  9. A multi-step process of viral adaptation to a mutagenic nucleoside analogue by modulation of transition types leads to extinction-escape.

    PubMed

    Agudo, Rubén; Ferrer-Orta, Cristina; Arias, Armando; de la Higuera, Ignacio; Perales, Celia; Pérez-Luque, Rosa; Verdaguer, Nuria; Domingo, Esteban

    2010-01-01

    Resistance of viruses to mutagenic agents is an important problem for the development of lethal mutagenesis as an antiviral strategy. Previous studies with RNA viruses have documented that resistance to the mutagenic nucleoside analogue ribavirin (1-β-D-ribofuranosyl-1-H-1,2,4-triazole-3-carboxamide) is mediated by amino acid substitutions in the viral polymerase that either increase the general template copying fidelity of the enzyme or decrease the incorporation of ribavirin into RNA. Here we describe experiments that show that replication of the important picornavirus pathogen foot-and-mouth disease virus (FMDV) in the presence of increasing concentrations of ribavirin results in the sequential incorporation of three amino acid substitutions (M296I, P44S and P169S) in the viral polymerase (3D). The main biological effect of these substitutions is to attenuate the consequences of the mutagenic activity of ribavirin -by avoiding the biased repertoire of transition mutations produced by this purine analogue-and to maintain the replicative fitness of the virus which is able to escape extinction by ribavirin. This is achieved through alteration of the pairing behavior of ribavirin-triphosphate (RTP), as evidenced by in vitro polymerization assays with purified mutant 3Ds. Comparison of the three-dimensional structure of wild type and mutant polymerases suggests that the amino acid substitutions alter the position of the template RNA in the entry channel of the enzyme, thereby affecting nucleotide recognition. The results provide evidence of a new mechanism of resistance to a mutagenic nucleoside analogue which allows the virus to maintain a balance among mutation types introduced into progeny genomes during replication under strong mutagenic pressure. PMID:20865120

  10. Targeted chemotherapy with cytotoxic bombesin analogue AN-215 inhibits growth of experimental human prostate cancers.

    PubMed

    Stangelberger, Anton; Schally, Andrew V; Letsch, Markus; Szepeshazi, Karoly; Nagy, Attila; Halmos, Gabor; Kanashiro, Celia A; Corey, Eva; Vessella, Robert

    2006-01-01

    We developed a powerful cytotoxic analogue of bombesin AN-215, in which the bombesin (BN)-like carrier peptide is conjugated to 2-pyrrolino doxorubicin (AN-201). Human prostate cancers express high levels of receptors for BN/gastrin releasing peptide (GRP) that can be used for targeted chemotherapy. The effects of targeted chemotherapy with cytotoxic BN analogue AN-215 were evaluated in nude mice bearing subcutaneous xenografts of DU-145, LuCaP-35, MDA-PCa-2b and intraosseous implants of C4-2 human prostate cancers. Intraosseous growth of C4-2 tumors was monitored by serum PSA. BN/GRP receptors were evaluated by 125I-[Tyr4]BN binding assays and RT-PCR. The effects of AN-215 on apoptosis and cell proliferation were followed by histology, and the expression of Bcl-2 and Bax protein was determined by Western blot analysis. Targeted analog AN-215 significantly inhibited growth of subcutaneously implanted DU-145, LuCaP-35 and MDA-PCa-2b prostate cancers by 81% to 91% compared to controls, while cytotoxic radical AN-201 was less effective and more toxic. Serum PSA levels of mice bearing intraosseous C4-2 prostate tumors were significantly reduced. In LuCaP-35 tumors administration of BN antagonist RC-3095 prior to AN-215 blocked the receptors for BN/GRP and inhibited the effects of AN-215. High affinity receptors for BN/GRP and their m-RNA were detected on membranes of all 4 tumor models. Therapy with AN-215, but not with AN-201, decreased the ratio of Bcl-2/Bax in DU-145 and the expression of antiapoptotic Bcl-2 in LuCaP-35 tumors. The presence of BN/GRP receptors on primary and metastatic prostate cancers makes possible targeted chemotherapy with AN-215 for the treatment of this malignancy. PMID:16003723

  11. Mutation V111I in HIV-2 Reverse Transcriptase Increases the Fitness of the Nucleoside Analogue-Resistant K65R and Q151M Viruses

    PubMed Central

    Deuzing, Ilona P.; Charpentier, Charlotte; Wright, David W.; Matheron, Sophie; Paton, Jack; Frentz, Dineke; van de Vijver, David A.; Coveney, Peter V.; Descamps, Diane; Boucher, Charles A. B.

    2014-01-01

    ABSTRACT Infection with HIV-2 can ultimately lead to AIDS, although disease progression is much slower than with HIV-1. HIV-2 patients are mostly treated with a combination of nucleoside reverse transcriptase (RT) inhibitors (NRTIs) and protease inhibitors designed for HIV-1. Many studies have described the development of HIV-1 resistance to NRTIs and identified mutations in the polymerase domain of RT. Recent studies have shown that mutations in the connection and RNase H domains of HIV-1 RT may also contribute to resistance. However, only limited information exists regarding the resistance of HIV-2 to NRTIs. In this study, therefore, we analyzed the polymerase, connection, and RNase H domains of RT in HIV-2 patients failing NRTI-containing therapies. Besides the key resistance mutations K65R, Q151M, and M184V, we identified a novel mutation, V111I, in the polymerase domain. This mutation was significantly associated with mutations K65R and Q151M. Sequencing of the connection and RNase H domains of the HIV-2 patients did not reveal any of the mutations that were reported to contribute to NRTI resistance in HIV-1. We show that V111I does not strongly affect drug susceptibility but increases the replication capacity of the K65R and Q151M viruses. Biochemical assays demonstrate that V111I restores the polymerization defects of the K65R and Q151M viruses but negatively affects the fidelity of the HIV-2 RT enzyme. Molecular dynamics simulations were performed to analyze the structural changes mediated by V111I. This showed that V111I changed the flexibility of the 110-to-115 loop region, which may affect deoxynucleoside triphosphate (dNTP) binding and polymerase activity. IMPORTANCE Mutation V111I in the HIV-2 reverse transcriptase enzyme was identified in patients failing therapies containing nucleoside analogues. We show that the V111I change does not strongly affect the sensitivity of HIV-2 to nucleoside analogues but increases the fitness of viruses with drug

  12. Dilazep analogues for the study of equilibrative nucleoside transporters 1 and 2 (ENT1 and ENT2).

    PubMed

    Playa, Hilaire; Lewis, Timothy A; Ting, Amal; Suh, Byung-Chul; Muñoz, Benito; Matuza, Robert; Passer, Brent J; Schreiber, Stuart L; Buolamwini, John K

    2014-12-15

    As ENT inhibitors including dilazep have shown efficacy improving oHSV1 targeted oncolytic cancer therapy, a series of dilazep analogues was synthesized and biologically evaluated to examine both ENT1 and ENT2 inhibition. The central diamine core, alkyl chains, ester linkage and substituents on the phenyl ring were all varied. Compounds were screened against ENT1 and ENT2 using a radio-ligand cell-based assay. Dilazep and analogues with minor structural changes are potent and selective ENT1 inhibitors. No selective ENT2 inhibitors were found, although some analogues were more potent against ENT2 than the parent dilazep. PMID:25454272

  13. Compound A398, a novel podophyllotoxin analogue: cytotoxicity and induction of apoptosis in human leukemia cells.

    PubMed

    Silveira, Alethéia L; Faheina-Martins, Glaúcia V; Maia, Raquel C; Araújo, Demetrius A M

    2014-01-01

    Despite advances in oncology research, cancer is one of the leading causes of death worldwide. Thus, there is a demand for the development of more selective and effective antitumor agents. This study showed that A398, a novel podophyllotoxin analogue, was cytotoxic to the HT-29, MCF-7, MOLT-4 and HL-60 tumor cell lines, being less active in human peripheral blood mononuclear cells and normal cell lines FGH and IEC-6. Tests using the HepG2 lineage indicated that its metabolites do not contribute to its cytotoxicity. In the HL-60 cells, A398 induced apoptosis in a time and concentration-dependent manner, promoting mitochondrial depolarization, inhibition of Bcl-2, phosphatidylserine exposure, activation of caspases -8, -9 and -3, and DNA fragmentation. The production of reactive oxygen species does not seem to be a crucial event for the apoptotic process. Pretreatment with specific inhibitors of kinases ERK1/2, JNK and p38 resulted in an increased percentage of death induced by A398. These results indicate that the compound induced apoptosis through activation of intrinsic and extrinsic death pathways with the mechanism involving the inhibition of the MAPKs and Bcl-2. Taken together, our findings suggest that A398 has an anticancer potential, proving itself to be a candidate for preclinical studies. PMID:25221997

  14. Selectivity and affinity of DNA triplex forming oligonucleotides containing the nucleoside analogues 2'-O-methyl-5-(3-amino-1-propynyl)uridine and 2'-O-methyl-5-propynyluridine.

    PubMed

    Li, Hong; Miller, Paul S; Seidman, Michael M

    2008-11-21

    Triplex forming oligonucleotides (TFOs) containing the nucleoside analogues 2'-O-methyl-5-propynyluridine (1) and 2'-O-methyl-5-(3-amino-1-propynyl)uridine (2) were synthesized. The affinity and selectivity of triplex formation by these TFOs were studied by gel shift analysis, T(m) value measurement, and association rate assays. The results show that the introduction of 1 and 2 into TFOs can improve the stability of the triplexes under physiological conditions. Optimized distribution of 1 or 2 in the TFOs combined with a cluster of contiguous nucleosides with 2'-aminoethoxy sugars resulted in formation of triplexes with further enhanced stability and improved selectivity. PMID:18972052

  15. Structure of a mutant human purine nucleoside phosphorylase with the prodrug, 2-fluoro-2-deoxyadenosine and the cytotoxic drug, 2-fluoroadenine

    SciTech Connect

    Afshar, Sepideh; Sawaya, Michael R.; Morrison, Sherie L.

    2009-06-30

    A double mutant of human purine nucleoside phosphorylase (hDM) with the amino acid mutations Glu201Gln:Asn243Asp cleaves adenosine-based prodrugs to their corresponding cytotoxic drugs. When fused to an anti-tumor targeting component, hDM is targeted to tumor cells, where it effectively catalyzes phosphorolysis of the prodrug, 2-fluoro-2'-deoxyadenosine (F-dAdo) to the cytotoxic drug, 2-fluoroadenine (F-Ade). This cytotoxicity should be restricted only to the tumor microenvironment, because the endogenously expressed wild type enzyme cannot use adenosine-based prodrugs as substrates. To gain insight into the interaction of hDM with F-dAdo, we have determined the crystal structures of hDM with F-dAdo and F-Ade. The structures reveal that despite the two mutations, the overall fold of hDM is nearly identical to the wild type enzyme. Importantly, the residues Gln201 and Asp243 introduced by the mutation form hydrogen bond contacts with F-dAdo that result in its binding and catalysis. Comparison of substrate and product complexes suggest that the side chains of Gln201 and Asp243 as well as the purine base rotate during catalysis possibly facilitating cleavage of the glycosidic bond. The two structures suggest why hDM, unlike the wild-type enzyme, can utilize F-dAdo as substrate. More importantly, they provide a critical foundation for further optimization of cleavage of adenosine-based prodrugs, such as F-dAdo by mutants of human purine nucleoside phosphorylase.

  16. Synthesis and Biological Evaluation of 2-Oxo/Thioxoquinoxaline and 2-Oxo/Thioxoquinoxaline-Based Nucleoside Analogues.

    PubMed

    El-Sayed, Hassan A; Said, Said A; Moustafa, Ahmed H; Baraka, Mohamed M; Abdel-Kader, Rimaa T

    2016-01-01

    Several O- and S-quinoxaline glycosides have been prepared by glycosidation of 3-methyl-2-oxo(thioxo)-1,2-dihydroquinoxalines 1a,b with α-D-glucopyranosyl, α-D-galactopyranosyl, and α-D-lactosyl bromide in the presence of K2CO3 followed by deacetylation with Et3N/H2O. Furthermore, alkylation of 1a,b with 4-bromobutyl acetate, 2-acetoxyethoxymethyl bromide, and 3-chloropropanol afforded the corresponding O- and S-acycloquinoxaline nucleosides. Reaction of 1b with chloroacetic acid followed by condensation with sulfacetamide and sulfadiazine in the presence of Et3N/THF and ethyl chloroformate gave the corresponding sulfonamide derivatives 14 and 15, respectively. The structures of new compounds were confirmed by using IR, (1)H, (13)C NMR spectra and microanalysis. Some of these compounds were screened in vitro for antitumor and antifungal activities. PMID:26810144

  17. Synthesis and antiviral activity of novel acyclic nucleoside analogues of 5-(1-azido-2-haloethyl)uracils.

    PubMed

    Kumar, R; Sharma, N; Nath, M; Saffran, H A; Tyrrell, D L

    2001-11-22

    We present the discovery of a novel category of 5-substituted acyclic pyrimidine nucleosides as potent antiviral agents. A series of 1-[(2-hydroxyethoxy)methyl] (5-7), 1-[(2-hydroxy-1-(hydroxymethyl)ethoxy)methyl] (8-10), and 1-[4-hydroxy-3-(hydroxymethyl)-1-butyl] (11-13) derivatives of 5-(1-azido-2-haloethyl)uracil were synthesized and evaluated for their biological activity in cell culture. 1-[4-Hydroxy-3-(hydroxymethyl)-1-butyl]-5-(1-azido-2-chloroethyl)uracil (12) was the most effective antiviral agent in the in vitro assays against DHBV (EC(50) = 0.31-1.55 microM) and HCMV (EC(50) = 3.1 microM). None of the compounds investigated showed any detectable toxicity to several stationary and proliferating host cells. PMID:11708924

  18. Relationships between the aqueous chemistry and the in vitro cytotoxic activities of mixed-amine cisplatin analogues.

    PubMed

    Bednarski, P J

    1992-06-23

    The possibility that variations in the cytotoxic activities of cisplatin analogues could be a result of differences in the aqueous chemistry of the compounds was investigated. A series of structurally related mixed-amine dichloroplatinum complexes (cis-coordinated with amine and various diphenylmethylamines and 1,2-diphenylethylamines) was prepared and selected physicochemical properties of the new compounds were characterized. Cytotoxicity was determined in two human breast cancer cell lines (MDA-MB-231 and MCF-7) and one human ovarian cancer cell line (SK-OV-3) by means of a microtiter assay. There is no apparent relationship between the hydrophobicities of the compounds and their cytotoxic potencies. There is no evidence for an inverse relationship between the aqueous stability of the dichloroplatinum complexes and cytotoxic potency, as has been reported for nitrogen mustards and some nitrosoureas. The differences in cytotoxic activity cannot be explained by inter-compound variations in the area under the concentration-time curves (AUC) of the dichloroplatinum complexes in culture medium. Thus, it appears that the differences in the cytotoxic potencies of this series of cisplatin analogues are related to factors other than dissimilarities in these physiochemical properties. Nevertheless, a relationship was found between the AUC of a dichloroplatinum complex in medium and the efficacy of the compound in the MCF-7 cell line. However, the AUC-efficacy relationship does not always hold in the MDA-MB-231 and SK-OV-3 cell lines. In these cells, treatment with a "high" bolus dose of platinum complex over finite exposure times is often less cytotoxic than treatment with lower doses of the same compound but over a continuous exposure time, although the cells are subjected to the same AUC of dichloroplatinum complex. PMID:1632817

  19. Efficient DNA strand displacement by a W-shaped nucleoside analogue (WNA-βT) containing an ortho-methyl-substituted phenyl ring.

    PubMed

    Aoki, Eriko; Taniguchi, Yosuke; Wada, Yasumasa; Sasaki, Shigeki

    2012-05-29

    Molecules that can target duplex DNA with sequence selectivity have the potential to be useful tools in genomic research and also as therapeutic agents. Homopurine-homopyrimidine stretches in duplex DNA can be recognized by homopurine or homopyrimidine TFOs (triplex-forming oligonucleotides) through the formation of triplex DNA. We have previously developed bicyclic nucleoside analogues (WNAs) for the formation of stable triplexes in the formation of stable antiparallel triplexes containing a TA or a CG interrupting site. In this study, we investigated the effects on triplex DNA formation of ortho-, meta-, and para-methyl substituent groups on the aromatic ring of the WNA analogue. It was found that the homopurine TFO containing meta- and para-methyl-substituted WNA-βT (mMe-WNA-βT, pMe-WNA-βT) stabilized triplexes containing a TA interrupting site or a GC site, respectively. Interestingly, the ortho-methyl-substituted WNA-βT (oMe-WNA-βT) efficiently promoted DNA strand displacement to form the TFO/pyrimidine duplex. A detailed investigation showed that the duplex was in the antiparallel orientation and that its formation took place prior to triplex formation with the need for a magnesium cation. NOESY measurements indicated a significant difference in the rotation flexibilities of the phenyl rings of WNA-βTs: that is, the conformation of the ortho-methylated phenyl ring was stable in a temperature-independent manner. It was speculated that the initial formation of a ternary complex was followed by strand displacement and then the formation of the TFO/pyrimidine duplex together with the TFO(2)/pyrimidine triplex formation during the early stage, and that the equilibrium shifted to the triplex during the later stage. Although the detailed role is still uncertain, the fixed phenyl ring of oMe-WNA-βT might play a role in the displacement reaction. PMID:22549913

  20. 2',5'-Bis-O-(tert-butyldimethylsilyl)-3'-spiro-5''-(4''-amino-1'',2''- oxathiole-2'',2'-dioxide)pyrimidine (TSAO) nucleoside analogues: highlyselective inhibitors of human immunodeficiency virus type 1 that are targeted at the viral reverse transcriptase.

    PubMed Central

    Balzarini, J; Pérez-Pérez, M J; San-Félix, A; Schols, D; Perno, C F; Vandamme, A M; Camarasa, M J; De Clercq, E

    1992-01-01

    A series of pyrimidine nucleoside analogues containing [2',5'-bis-O-(tert-butyldimethylsilyl)-3'-spiro-5''-(4''-amino- 1'',2''-oxathiole-2'',2''-dioxide)]-beta-D-ribofuranose as the pentose were found to inhibit human immunodeficiency virus type 1 [HIV-1(IIIB)] replication at a concentration of 0.06-0.8 microM but were not cytotoxic at a 1000- to 10,000-fold higher concentration. These nucleoside derivatives were also effective against various other HIV-1 strains, including those resistant to 3'-azido-3'-deoxythymidine, but not against HIV-2, simian immunodeficiency virus, Moloney murine sarcoma virus, or other RNA or DNA viruses. They proved to be highly specific inhibitors of the RNA-dependent DNA polymerase function of the HIV-1 reverse transcriptase, showing no marked inhibition of the HIV-1 reverse transcriptase-associated DNA-dependent DNA polymerase activity, HIV-2 reverse transcriptase, DNA polymerase alpha, herpes simplex virus 1 DNA polymerase, or Thermus aquaticus DNA polymerase. Images PMID:1374900

  1. Constrained nucleoside analogues - Crystal and molecular structure of 6,5‧-O-anhydrouridines fixed in the anti conformation

    NASA Astrophysics Data System (ADS)

    Gajda, Roman; Bagiński, Maciej; Tomczyk, Ewelina; Mieczkowski, Adam; Woźniak, Krzysztof

    2015-10-01

    A series of analogues of anhydrouridine have been synthesized and their crystal structures established using X-ray diffraction. For all cases, the ribose ring has O(4‧)-exo, C(4‧)-endo pucker and the pyrimidine base is in the anti conformation. Investigated compounds crystallize in different crystal systems (monoclinic, orthorhombic), have different space group symmetry (P21, P212121) and exhibit different intermolecular interactions (halogen and hydrogen bonds) among molecules in their crystal lattices. Moreover, in the case of the 5-benzyl-6,5‧-O-anhydrouridine a significant positional disorder is present with the phenyl rings existing in two orientations.

  2. [Detecting the cytotoxicities of five bisphenol A analogues to the MCF-7 human breast carcinoma cell line through different endpoints].

    PubMed

    Zhang, Shuai-Shuai; Liu, Yan; Liu, Shu-Shen; Zhu, Xiang-Wei

    2012-11-01

    As the main synthetic raw materials of polycarbonate, bisphenol A (BPA) and its analogues have been important issues in environmental pollution. The current studies focus mainly on BPA's estrogen effects and little on their cytotoxic effects. To assess the cytotoxicities of the five BPA analogues, we employed the MTS assay to determine the inhibition toxicity to MCF-7 (ER-), 2,4-dinitrophenylhydrazine assay to determine the release rate of lactate dehydrogenase (LDH) escaping into cell culture medium, and single cell gel electrophoresis assay (SCGE) to detect DNA damage. The dose-response curves (DRC) between the observed inhibition toxicities and concentrations of the BPA compounds in MTS assay were fitted by using the nonlinear least squares (NLS) and the results showed that all the dose-response relationships were effectively described by the Weibull or Logit function. The toxicities expressed by--lgpEC50 were BPB > BPC > TDP > BPE > BPA. LDH assay and SCGE assay showed that when the concentrations of BPA analogues were EC20, the MCF-7 cell proliferation was slightly inhibited due to its little damaged DNA, and at EC40 the cell proliferations were significantly inhibited due to the seriously damaged DNA, leading to the damage of cell membrane and release of LDH. PMID:23323428

  3. Cytotoxic and Antihaptotactic beauvericin analogues from precursor-directed biosynthesis with the insect pathogen Beauveria bassiana ATCC 7159.

    PubMed

    Xu, Yuquan; Zhan, Jixun; Wijeratne, E M Kithsiri; Burns, Anna M; Gunatilaka, A A Leslie; Molnár, István

    2007-09-01

    Precursor-directed biosynthesis was used to produce analogues of the cyclic depsipeptide mycotoxin beauvericin (1) using the filamentous fungus Beauveria bassiana ATCC 7159. Feeding 30 analogues of D-2-hydroxyisovalerate and L-phenylalanine, the natural 2-hydroxycarboxylic acid and amino acid precursors of beauvericin, led to the biosynthesis of novel beauvericins. Six of these were isolated and characterized, and their cytotoxicity and directional cell migration (haptotaxis) inhibitory activity against the metastatic prostate cancer cell line PC-3M were evaluated. Replacement of one, two, or all three of the D-2-hydroxyisovalerate constituents in beauvericin (1) with 2-hydroxybutyrate moieties (beauvericins G(1-3), compounds 2-4) caused a parallel decline of cell migration inhibitory activity and cytotoxicity, suggesting a requirement for a branched side chain for both of these biological activities at the corresponding positions of beauvericins. Replacement of one, two, or all three N-methyl-L-phenylalanine residues of beauvericin with N-methyl-L-3-fluorophenylalanine moieties (beauvericins H(1-3), compounds 5-7) increased cytotoxicity without affecting antihaptotactic activity. PMID:17803266

  4. Nucleoside inhibitors of tick-borne encephalitis virus.

    PubMed

    Eyer, Luděk; Valdés, James J; Gil, Victor A; Nencka, Radim; Hřebabecký, Hubert; Šála, Michal; Salát, Jiří; Černý, Jiří; Palus, Martin; De Clercq, Erik; Růžek, Daniel

    2015-09-01

    Tick-borne encephalitis virus (TBEV) is a leading cause of human neuroinfections in Europe and Northeast Asia. There are no antiviral therapies for treating TBEV infection. A series of nucleoside analogues was tested for the ability to inhibit the replication of TBEV in porcine kidney cells and human neuroblastoma cells. The interactions of three nucleoside analogues with viral polymerase were simulated using advanced computational methods. The nucleoside analogues 7-deaza-2'-C-methyladenosine (7-deaza-2'-CMA), 2'-C-methyladenosine (2'-CMA), and 2'-C-methylcytidine (2'-CMC) inhibited TBEV replication. These compounds showed dose-dependent inhibition of TBEV-induced cytopathic effects, TBEV replication (50% effective concentrations [EC50]of 5.1 ± 0.4 μM for 7-deaza-2'-CMA, 7.1 ± 1.2 μM for 2'-CMA, and 14.2 ± 1.9 μM for 2'-CMC) and viral antigen production. Notably, 2'-CMC was relatively cytotoxic to porcine kidney cells (50% cytotoxic concentration [CC50] of ∼50 μM). The anti-TBEV effect of 2'-CMA in cell culture diminished gradually after day 3 posttreatment. 7-Deaza-2'-CMA showed no detectable cellular toxicity (CC50 > 50 μM), and the antiviral effect in culture was stable for >6 days posttreatment. Computational molecular analyses revealed that compared to the other two compounds, 7-deaza-2'-CMA formed a large cluster near the active site of the TBEV polymerase. High antiviral activity and low cytotoxicity suggest that 7-deaza-2'-CMA is a promising candidate for further investigation as a potential therapeutic agent in treating TBEV infection. PMID:26124166

  5. Nucleoside Inhibitors of Tick-Borne Encephalitis Virus

    PubMed Central

    Eyer, Luděk; Valdés, James J.; Gil, Victor A.; Nencka, Radim; Hřebabecký, Hubert; Šála, Michal; Salát, Jiří; Černý, Jiří; Palus, Martin; De Clercq, Erik

    2015-01-01

    Tick-borne encephalitis virus (TBEV) is a leading cause of human neuroinfections in Europe and Northeast Asia. There are no antiviral therapies for treating TBEV infection. A series of nucleoside analogues was tested for the ability to inhibit the replication of TBEV in porcine kidney cells and human neuroblastoma cells. The interactions of three nucleoside analogues with viral polymerase were simulated using advanced computational methods. The nucleoside analogues 7-deaza-2′-C-methyladenosine (7-deaza-2′-CMA), 2′-C-methyladenosine (2′-CMA), and 2′-C-methylcytidine (2′-CMC) inhibited TBEV replication. These compounds showed dose-dependent inhibition of TBEV-induced cytopathic effects, TBEV replication (50% effective concentrations [EC50]of 5.1 ± 0.4 μM for 7-deaza-2′-CMA, 7.1 ± 1.2 μM for 2′-CMA, and 14.2 ± 1.9 μM for 2′-CMC) and viral antigen production. Notably, 2′-CMC was relatively cytotoxic to porcine kidney cells (50% cytotoxic concentration [CC50] of ∼50 μM). The anti-TBEV effect of 2′-CMA in cell culture diminished gradually after day 3 posttreatment. 7-Deaza-2′-CMA showed no detectable cellular toxicity (CC50 > 50 μM), and the antiviral effect in culture was stable for >6 days posttreatment. Computational molecular analyses revealed that compared to the other two compounds, 7-deaza-2′-CMA formed a large cluster near the active site of the TBEV polymerase. High antiviral activity and low cytotoxicity suggest that 7-deaza-2′-CMA is a promising candidate for further investigation as a potential therapeutic agent in treating TBEV infection. PMID:26124166

  6. Peripheral and visceral fat changes following a treatment switch to a non-thymidine analogue or a nucleoside-sparing regimen in HIV-infected subjects with peripheral lipoatrophy: results of ACTG A5110

    PubMed Central

    Tebas, P.; Zhang, J.; Hafner, R.; Tashima, K.; Shevitz, A.; Yarasheski, K.; Berzins, B.; Owens, S.; Forand, J.; Evans, S.; Murphy, R.

    2009-01-01

    Background Switching a thymidine analogue to a non-thymidine analogue or changing to a nucleoside-sparing regimen has been shown to partially reverse peripheral lipoatrophy. The current study evaluated both approaches. Methods Subjects at 15 AIDS Clinical Trial Group sites receiving thymidine analogue stavudine- or zidovudine-containing regimens with plasma HIV RNA ≤500 copies/mL and lipoatrophy were prospectively randomized to: (i) switch the thymidine analogue to abacavir; (ii) discontinue all antiretrovirals and switch to lopinavir/ritonavir plus nevirapine (LPV/r+NVP); or (iii) delay switching for 24 weeks (ClinicalTrials.gov identifier: NCT00028314). Single-slice computer tomography of mid-thigh and abdominal fat and metabolic and virological/immunological parameters were measured at baseline and weeks 24 and 48. Results Among the 101 patients enrolled, there were significant subcutaneous thigh fat and subcutaneous abdominal tissue (SAT) increases over time and decreases in visceral adipose tissue to total adipose tissue (VAT:TAT) ratios for both interventions, and a decrease in VAT for abacavir. CD4 increased in the LPV/r+NVP arm. LPV/r+NVP had a significantly shorter time to grade 3 or higher toxicity (P = 0.007), but discontinuation rates were similar. Glucose levels did not change, but insulin decreased in the LPV/r+NVP arm. Lipids tended to increase in the LPV/r+NVP arm. Conclusions Switching stavudine or zidovudine to a non-thymidine analogue or changing to a nucleoside reverse transcriptase inhibitor-sparing regimen is associated with qualitatively similar improvements in thigh fat, SAT and VAT:TAT ratio at 48 weeks. Abacavir also resulted in VAT reductions and LPV/r+NVP resulted in CD4 count increases. PMID:19299471

  7. Selective Cytotoxicity against Human Osteosarcoma Cells by a Novel Synthetic C-1 Analogue of 7-Deoxypancratistatin Is Potentiated by Curcumin

    PubMed Central

    Ma, Dennis; Tremblay, Phillip; Mahngar, Kevinjeet; Collins, Jonathan; Hudlicky, Tomas; Pandey, Siyaram

    2011-01-01

    The natural compound pancratistatin (PST) is a non-genotoxic inducer of apoptosis in a variety of cancers. It exhibits cancer selectivity as non-cancerous cells are markedly less sensitive to PST. Nonetheless, PST is not readily synthesized and is present in very low quantities in its natural source to be applied clinically. We have previously synthesized and evaluated several synthetic analogues of 7-deoxypancratistatin, and found that JC-TH-acetate-4 (JCTH-4), a C-1 acetoxymethyl analogue, possessed similar apoptosis inducing activity compared to PST. In this study, notoriously chemoresistant osteosarcoma (OS) cells (Saos-2, U-2 OS) were substantially susceptible to JCTH-4-induced apoptosis through mitochondrial targeting; JCTH-4 induced collapse of mitochondrial membrane potential (MMP), increased reactive oxygen species (ROS) production in isolated mitochondria, and caused release of apoptosis inducing factor (AIF) and endonuclease G (EndoG) from isolated mitochondria. Furthermore, JCTH-4 selectively induced autophagy in OS cells. Additionally, we investigated the combinatory effect of JCTH-4 with the natural compound curcumin (CC), a compound found in turmeric spice, previously shown to possess antiproliferative properties. CC alone had no observable effect on Saos-2 and U-2 OS cells. However, when present with JCTH-4, CC was able to enhance the cytotoxicity of JCTH-4 selectively in OS cells. Such cytotoxicity by JCTH-4 alone and in combination with CC was not observed in normal human osteoblasts (HOb) and normal human fetal fibroblasts (NFF). Therefore, this report illustrates a new window in combination therapy, utilizing a novel synthetic analogue of PST with the natural compound CC, for the treatment of OS. PMID:22205968

  8. An efficient antigene activity and antiproliferative effect by targeting the Bcl-2 or survivin gene with triplex forming oligonucleotides containing a W-shaped nucleoside analogue (WNA-βT).

    PubMed

    Taniguchi, Yosuke; Sasaki, Shigeki

    2012-10-01

    Triplex forming oligonucleotides (TFOs) are some of the most promising tools in the antigene strategy for the development of gene targeting therapeutics. However, the stable triplex formation is restricted to the homopurine sequences consisting of purine nucleosides, dG and dA. Therefore, the T or dC nucleoside in the homopurine strand inhibits the stable triplex formation. We have developed W-shaped nucleoside analogues (WNAs) for the formation of the unnatural type triplex DNA, with sequences containing the interrupting site in an antiparallel triplex formation. In the present study, we tested the antigene effect of TFOs having WNA-βT, which increased the stability of the triplex formation with a target sequence including the TA interrupting site. We designed the GU TFO (WNA) and GU TFO (natural) for targeting sequences of the Bcl-2 or survivin oncogene. The gel shift assay showed that the TFO (WNA) formed more stable triplexes than the natural TFO. Remarkably, the Bcl-2- or survivin-targeted TFO (WNA) inhibited the cell proliferation and induced a caspase-dependent apoptosis. It was confirmed that the survivin-targeted TFO (WNA) more effectively decreased the number of survivin products in the A549 cell than the natural TFOs. PMID:22987068

  9. Evaluation Of Microdosing Strategies For Studies In Preclinical Drug Development: Demonstration Of Linear Pharmacokinetics In Dogs Of A Nucleoside Analogue Over A 50-Fold Dose Range

    SciTech Connect

    Sandhu, P; Vogel, J S; Rose, M J; Ubick, E A; Brunner, J E; Wallace, M A; Adelsberger, J K; Baker, M P; Henderson, P T; Pearson, P G; Baillie, T A

    2004-04-22

    (Stafford et al., 1984; Vogel et al., 1990; Smith et al., 1999) to its use as a bioanalytical tool for nutritional research (Buchholz et al., 1999; Deuker et al., 2000; Weaver and Liebman, 2002). Biomedical applications of AMS and its use in the arena of pharmaceutical research also have been detailed in review articles (Barker and Garner, 1999; Garner, 2000; Turteltaub and Vogel, 2000). To date, most studies on the metabolism and disposition of xenobiotics by AMS have focused on how carcinogens bind to DNA and proteins to form adducts (Turteltaub et al., 1990, 1997; Frantz et al., 1995; Dingley et al., 1999; Li et al., 2003). Its application to the field of pharmaceutical sciences has been limited to a few studies (Kaye et al., 1997; Young et al., 2001; Garner et al., 2002). However, the pharmaceutical industry is becoming increasingly aware of the potential benefits that may accrue from the ultra high sensitivity afforded by AMS in terms of evaluating the pharmacokinetics of lead drug candidates in early development. Specifically, AMS allows administration of sub-pharmacological doses (microdoses) of carbon-14 or tritium-labeled investigational drugs to animals or humans at radiologically insignificant levels with the goal of obtaining preliminary information regarding the absorption, distribution, metabolism, and excretion of test compounds (Turteltaub and Vogel, 2000). An unresolved issue, however, is whether the pharmacokinetics determined following a microdose are representative of those following a conventional (pharmacological) dose (Lappin and Garner, 2003). This paper examines the linearity of kinetics of an antiviral nucleoside analogue, Compound A, across sub-pharmacological and pharmacological dose ranges in the dog prior to initiation of a human microdose study. The specific objectives of this study, therefore, were (1) to assess the pharmacokinetics of Compound A in dogs by a conventional dosing approach utilizing LC-MS/MS for sample analysis, (2) to assess

  10. A new class of acyclic nucleoside phosphonates: synthesis and biological activity of 9-[[(phosphonomethyl)aziridin-1-yl]methyl]guanine (PMAMG) and analogues.

    PubMed

    Abu Sheikha, Ghassan; La Colla, Paolo; Loi, Anna Giulia

    2002-10-01

    A new class of acyclic nucleoside phosphonates PMAMG, PMAMA, PMAMC, and PMAMT (compounds 1, 2, 3 and 4) have been synthesized and tested in vitro against a wide variety of viruses, fungi and bacteria. PMAMG (1) was synthesized by the alkylation reaction of acetylguanine with the phosphonate side-chain, diisopropyl [[2-(bromomethyl)aziridin-1-yl

  11. Oxygen and exposure kinetics as factors influencing the cytotoxicity of porfiromycin, a mitomycin C analogue, in Chinese hamster ovary cells.

    PubMed

    Marshall, R S; Rauth, A M

    1988-10-15

    Some factors affecting the cytotoxicity of porfiromycin (PM), an analogue of mitomycin C (MMC), were investigated in suspension cultures of wild-type (AA8-4) and repair-deficient (UV-20) Chinese hamster ovary cells. Oxygen was an important modulator of PM toxicity in AA8-4 cells. The aerobic toxicity was significantly less, and toxicity under extremely hypoxic conditions was significantly greater for PM than MMC. Porfiromycin cytotoxicity at intermediate O2 levels was similar to that observed previously for MMC. While the aerobic/hypoxic ratio was greater for PM than MMC, survival at intermediate oxygen concentrations could limit the therapeutic utility of these drugs as adjuncts to radiotherapy. Ascorbic acid was found to increase the aerobic, but not hypoxic, cytotoxicity of PM in AA8-4 cells, as was observed previously for MMC. Investigation of various exposure times and drug concentrations revealed that drug toxicity for both aerobic and hypoxic cells was dependent on the product of drug concentration and time, and that the aerobic/hypoxic differential observed in AA8-4 cells was constant over a broad range of exposure conditions. The sensitivity of UV-20 cells was also a linear function of concentration and time, but no aerobic/hypoxic differential was observed in these cells. It is suggested that the sensitivity of UV-20 to PM and MMC, and its lack of an hypoxic/aerobic differential could result from lethality being due to a different lesion than in wild-type cells. PMID:3167822

  12. Cytotoxic Effects of Tetracycline Analogues (Doxycycline, Minocycline and COL-3) in Acute Myeloid Leukemia HL-60 Cells

    PubMed Central

    Maguire, Kim R.; Sidén, Åke; Potácová, Zuzana

    2014-01-01

    Tetracycline analogues (TCNAs) have been shown to inhibit matrix metalloproteinases and to induce apoptosis in several cancer cell types. In the present study, the cytotoxic effects of TCNAs doxycycline (DOXY), minocycline (MINO) and chemically modified tetracycline-3 (COL-3) were investigated in the human acute myeloid leukemia HL-60 cell line. Cells were incubated with TCNAs in final concentrations of 0.5–100 µg/ml for 24 h. Viability of the leukemic cells was inhibited in a concentration-dependent manner using resazurin assay. The estimated IC50s were 9.2 µg/ml for DOXY, 9.9 µg/ml for MINO and 1.3 µg/ml for COL-3. All three TCNAs induced potent cytotoxic effects and cell death. Apoptosis, which was assessed by morphological changes and annexin V positivity, was concentration- and time-dependent following incubation with any one of the drugs. TCNAs induced DNA double strand breaks soon after treatment commenced as detected by γH2AX and western blot. The loss of mitochondrial membrane potential (Δψm), caspase activation and cleavage of PARP and Bcl-2 were observed; however, the sequence of events differed among the drugs. Pancaspase inhibitor Z-VAD-FMK improved survival of TCNAs-treated cells and decreased TCNAs-induced apoptosis. In summary, we demonstrated that TCNAs had a cytotoxic effect on the HL-60 leukemic cell line. Apoptosis was induced via mitochondria-mediated and caspase-dependent pathways in HL-60 cells by all three TCNAs. COL-3 exerted the strongest anti-proliferative and pro-apoptotic effects in concentrations that have been achieved in human plasma in reported clinical trials. These results indicate that there is a therapeutic potential of TCNAs in leukemia. PMID:25502932

  13. Synthesis and cytotoxic activity of a new group of heterocyclic analogues of the combretastatins.

    PubMed

    Lipeeva, Alla V; Shults, Elvira E; Shakirov, Makhmut M; Pokrovsky, Mikhail A; Pokrovsky, Andrey G

    2014-01-01

    A series of new analogs of combretastatin A-4 (CA-4, 1) with the A or B-ring replaced by a 3-oxo-2,3-dihydrofurocoumarin or a furocoumarin residue have been designed and synthesized by employing a cross-coupling approach. All the compounds were evaluated for their cytotoxic activity with respect to model cancer cell lines (CEM-13, MT-4, U-937) using conventional MTT assays. Structure-activity relationship analysis reveals that compounds 2, 3, 6-8 in which the (Z)-styryl substituent was connected to the 2-position of the 3-oxo-2,3-dihydrofurocoumarin core, demonstrated increased potency compared to 3-(Z)-styrylfurocoumarins 4, 5, 9-11. The methoxy-, hydroxyl- and formyl- substitution on the aromatic ring of the (Z)-styryl moiety seems to play an important role in this class of compounds. Compounds 2 and 3 showed the best potency against the CEM-13 cell lines, with CTD50 values ranging from 4.9 to 5.1 μM. In comparison with CA-4, all synthesized compounds presented moderate cytotoxic activity to the T-cellular human leucosis cells MT-4 and lymphoblastoid leukemia cells CEM-13, but most of them were active in the human monocyte cell lines U-937. PMID:24962392

  14. Genotoxicity and Cytotoxicity Evaluation of the Neolignan Analogue 2-(4-Nitrophenoxy)-1Phenylethanone and its Protective Effect Against DNA Damage

    PubMed Central

    Hanusch, Alex Lucas; de Oliveira, Guilherme Roberto; de Sabóia-Morais, Simone Maria Teixeira; Machado, Rafael Cosme; dos Anjos, Murilo Machado; Chen Chen, Lee

    2015-01-01

    Neolignans are secondary metabolites found in various groups of Angiosperms. They belong to a class of natural compounds with great diversity of chemical structures and pharmacological activities. These compounds are formed by linking two phenylpropanoid units. Several compounds that have ability to prevent genetic damage have been isolated from plants, and can be used to prevent or delay the development of tumor cells. Genetic toxicology evaluation is widely used in risk assessment of new drugs in preclinical screening tests. In this study, we evaluated the genotoxicity and cytotoxicity of the neolignan analogue 2-(4-nitrophenoxy)-1-phenylethanone (4NF) and its protective effect against DNA damage using the mouse bone marrow micronucleus test and the comet assay in mouse peripheral blood. Our results showed that this neolignan analogue had no genotoxic activity and was able to reduce induced damage both in mouse bone marrow and peripheral blood. Although the neolignan analogue 4NF was cytotoxic, it reduced cyclophosphamide-induced cytotoxicity. In conclusion, it showed no genotoxic action, but exhibited cytotoxic, antigenotoxic, and anticytotoxic activities. PMID:26554835

  15. 2-Aryl-8-aza-3-deazaadenosine analogues of 5'-O-[N-(salicyl)sulfamoyl]adenosine: Nucleoside antibiotics that block siderophore biosynthesis in Mycobacterium tuberculosis.

    PubMed

    Krajczyk, Anna; Zeidler, Joanna; Januszczyk, Piotr; Dawadi, Surendra; Boshoff, Helena I; Barry, Clifton E; Ostrowski, Tomasz; Aldrich, Courtney C

    2016-07-15

    A series of 5'-O-[N-(salicyl)sulfamoyl]-2-aryl-8-aza-3-deazaadenosines were designed to block mycobactin biosynthesis in Mycobacterium tuberculosis (Mtb) through inhibition of the essential adenylating enzyme MbtA. The synthesis of the 2-aryl-8-aza-3-deazaadenosine nucleosides featured sequential copper-free palladium-catalyzed Sonogashira coupling of a precursor 4-cyano-5-iodo-1,2,3-triazolonucleoside with terminal alkynes and a Minakawa-Matsuda annulation reaction. These modified nucleosides were shown to inhibit MbtA with apparent Ki values ranging from 6.1 to 25nM and to inhibit Mtb growth under iron-deficient conditions with minimum inhibitory concentrations ranging from 12.5 to >50μM. PMID:27265685

  16. Tyrosine transport in a human melanoma cell line as a basis for selective transport of cytotoxic analogues.

    PubMed Central

    Pankovich, J M; Jimbow, K

    1991-01-01

    Tyrosine is an essential amino acid for the initial step of melanin synthesis, yet little is known concerning its transport in melanocytes. As an important first step in the development of new anti-melanoma agents based upon chemical and pharmacological modifications of melanin synthesis, the present study characterized the transport mechanism of tyrosine in vitro using the human melanoma cell line SK-MEL 23. Several tyrosine transport systems may be involved in melanocytes: systems L and T, which transport neutral amino acids with branched or aromatic side chains, and systems A and ASC, which transport neutral amino acids with smaller side chains. In order to determine which system or combination of systems is involved in tyrosine transport in melanoma cells, studies of kinetics, Na(+)-dependence and competitive inhibition were undertaken. The Km and Vmax. for the Na(+)-independent transport system were found to be 0.164 +/- 0.016 mM and 21.6 +/- 1.1 nmol/min per mg of protein respectively. This transport was preferentially inhibited by the system L specific analogue, 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid, the system T substrate tryptophan, and the sulphur homologue of tyrosine, 4-S-cysteinylphenol. Sequential addition of these inhibitors at increasing concentrations indicated that they inhibit the same transporter. Our results suggest that tyrosine transport in SK-MEL 23 melanoma cells is similar to system L transport previously characterized in other cell types. This one transport system appears to supply all the tyrosine required for both cell growth and melanin synthesis. The transport system may be subject to manipulation by melanogenic stimulating factors, making the transport of cytotoxic tyrosine analogues an important area for further study. PMID:1764036

  17. Organic Cation Transporters Modulate the Uptake and Cytotoxicity of Picoplatin, a Third-Generation Platinum Analogue

    PubMed Central

    More, Swati S.; Li, Shuanglian; Yee, Sook Wah; Chen, Ligong; Xu, Zhidong; Jablons, David M.; Giacomini, Kathleen M.

    2012-01-01

    Picoplatin, a third-generation platinum agent, is efficacious against lung cancers that are otherwise resistant or become refractory during platinum treatment. This effort was aimed at the determination of the influence of organic cation transporters 1, 2, and 3 (OCT1, OCT2, and OCT3) and their genetic variants on cellular uptake of picoplatin and on the individual components of the ensuing cytotoxicity such as DNA adduct formation. The effect of OCT1 on picoplatin pharmacokinetics and antitumor efficacy was determined using OCT knockout mice and HEK293 xenografts stably expressing OCT1. The uptake and DNA adduct formation of picoplatin were found to be significantly enhanced by the expression of the OCTs. Expression of OCT1 and OCT2, but not OCT3, significantly enhanced picoplatin cytotoxicity, which was reduced in the presence of an OCT inhibitor. Common reduced functional variants of OCT1 and OCT2 led to reduction in uptake and DNA adduct formation of picoplatin in comparison with the reference OCT1 and OCT2. Pharmacokinetic parameters of picoplatin in Oct1−/− and Oct1+/+ mice were not significantly different, suggesting that the transporters do not influence the disposition of the drug. In contrast, the volume of OCT1-expressing xenografts in mice was significantly reduced by picoplatin treatment, suggesting that OCT1 may enhance the antitumor efficacy of picoplatin. These studies provide a basis for follow-up clinical studies that would seek to examine the relationship between the anticancer efficacy of picoplatin and expression levels of OCTs and their genetic variants in tumors. PMID:20371711

  18. Bispidin-9,9-diol Analogues of Cisplatin, Carboplatin, and Oxaliplatin: Synthesis, Structures, and Cytotoxicity.

    PubMed

    Cui, Huiling; Goddard, Richard; Pörschke, Klaus-Richard; Hamacher, Alexandra; Kassack, Matthias U

    2016-03-21

    3,7-Diallyl-bispidin-9-one (6) (bispidin-9-one = 3,7-diazabicyclo[3.3.1]nonan-9-one) is converted to N-unsubstituted spiro[bispidin-9,2'-[1,3]dioxolane] (12; 35%). The ketal crystallizes in the forms of anhydrous 12a and the dihydrate 12b. The molecules in anhydrous 12a are linked to each other, forming N1-H1···N2-H2···N1* hydrogen-bond chiral helices of alternating chirality. In the dihydrate 12b, the ketal molecules are connected to a central string of water molecules by O3-H···O1 and O4-H···N1 hydrogen bonds, but not to themselves. Reaction of 12 with (1,5-hexadiene)PtCl2 affords almost quantitatively spiro[bispidin-9,2'-[1,3]dioxolane]PtCl2 (13). Cleavage of the ketal to retrieve the ketone produces the geminal diol (bispidin-9,9-diol)PtCl2 (14; 85%). Compound 14 reacts with Ag2cbdca (cbdca = 1,1-cyclobutanedicarboxylate) to give the dihydrate (bispidin-9,9-diol)Pt(cbdca)·2H2O (15b), which can be dehydrated to obtain anhydrous (bispidin-9,9-diol)Pt(cbdca) (15a). Similarly, anhydrous (bispidin-9,9-diol)Pt(oxalate) (16) is obtained. Crystal structures of 14 and 15b reveal association by various forms of O-H···O, O-H···Cl, N-H···Cl, and N-H···O hydrogen bonds. Biological studies showed a moderate cytotoxic activity of the bispidin-9,9-diol complexes 14-16, compared to the 9,9-unsubstituted bispidine complexes. No unspecific cytotoxicity of 14-16 up to 316 μM was found against the noncancer cell line HEK293. PMID:26918619

  19. Synthesis and spectroscopic characterization of fluorescent 4-aminoantipyrine analogues: Molecular docking and in vitro cytotoxicity studies

    NASA Astrophysics Data System (ADS)

    Premnath, D.; Mosae Selvakumar, P.; Ravichandiran, P.; Tamil Selvan, G.; Indiraleka, M.; Jannet Vennila, J.

    2016-01-01

    Two substituted aromatic carbonyl compounds (compounds 1 and 2) of 4-aminoantipyrine were synthesized by condensation of fluorine substituted benzoyl chlorides and 4-aminoantipyrine. The structures of synthesized derivatives were established on the basis of UV-Vis, IR, and Mass, 1H, 13C NMR and Fluorescence spectroscopy. Both compounds showed significant fluorescence emission and two broad emission bands were observed in the region at 340 nm and 450 nm on excitation at 280 nm. Theoretically to prove that the molecule has anticancer activity against cervical cancer cells, the compounds were analyzed for molecular docking interactions with HPV16-E7 target protein by Glide protocol. Furthermore, 4-aminoantipyrine derivatives were evaluated for their in vitro cytotoxic activity against human cervical cancer cells (SiHa) by MTT assay. Compound 1 showed two fold higher activity (IC50 = 0.912 μM) over compound 2, and its activity was similar to that of Pazopanib, suggesting that although the two compounds were chemically very similar the difference in substituent on the phenyl moiety caused changes in properties.

  20. DNA interactions and cytotoxic studies of cis-platin analogues of substituted 2,2'-bipyridines

    NASA Astrophysics Data System (ADS)

    Patel, Mohan N.; Parmar, Pradhuman A.; Gandhi, Deepen S.; Patidar, Anshul P.

    2012-11-01

    Platinum(II) complexes [Pt(4″-fpbpy)Cl2] (1), [Pt(4″-mepbpy)Cl2] (2), [Pt(4″-mpbpy)Cl2] (3) and [Pt(4″-bopbpy)Cl2] (4) {where 4″-fpbpy = 4-(4″-fluorophenyl)-6-phenyl-2,2'-bipyridine, 4″-mepbpy = 4-(4″-methylphenyl)-6-phenyl-2,2'-bipyridine, 4″-mpbpy = 4-(4″-methoxyphenyl)-6-phenyl-2,2'-bipyridine, 4″-bopbpy = 4-(4″-benzyloxyphenyl)-6-phenyl-2,2'-bipyridine} have been synthesized and characterized. The binding strength and binding mode of the complexes with HS DNA (Herring Sperm) have been investigated by absorption titration and viscosity measurement studies. The results have been revealed that the complexes bind to DNA by covalent mode with intrinsic binding constant Kb ranging from 6.05 × 104 M-1 to 3.48 × 105 M-1. The unwinding angle of pUC19 DNA has been evaluated by gel electrophoresis assay. The brine shrimp bioassay has been performed to study the in vitro cytotoxic properties of the synthesized metal complexes.

  1. Effects of the ACTH(4-9) analogue, ORG 2766, on vincristine cytotoxicity in two human lymphoma cell lines, U937 and U715.

    PubMed Central

    Kiburg, B.; van de Loosdrecht, A. A.; Schweitzer, K. M.; Ossenkoppele, G. J.; Müller, L. J.; Heimans, J. J.; Huijgens, P. C.

    1994-01-01

    The use of cytotoxic drug vincristine (VCR) is limited by the occurrence of peripheral neuropathy. A neurotrophic ACTH(4-9) analogue, ORG 2766, is being studied for its protective effect. Possible modulatory effects of ORG 2766 on tumour cell growth and interference with the cytotoxic efficacy of VCR were studied in two human lymphoma cell lines, U937 and U715. The effects of ORG 2766 on cell growth and survival and on VCR-mediated cytotoxicity were investigated using two MTT-based assays to study direct cytotoxic effects and to assess residual growth after pretreatment. Treatment with ORG 2766 alone had no effect on cell growth and survival. Neither did this drug affect VCR cytotoxicity. However, after 96 h pretreatment with ORG 2766 and a culture period of 7 days, a reduction in residual growth and a potentiation of VCR-induced inhibition of growth capacity was observed in U715 cells, and to some extent also in U937 cells. It is concluded that ORG 2766 has no stimulatory effects on tumour growth and does not negatively interfere with VCR-mediated cytotoxicity. Rather it enhances the cytostatic effect of VCR. It is suggested that ORG 2766 can safely be used in clinical trials investigating the ability of ORG 2766 to counteract VCR-induced neurotoxicity. PMID:8123480

  2. Carbocyclic pyrimidine nucleosides as inhibitors of S-adenosylhomocysteine hydrolase.

    PubMed

    Mosley, Sylvester L; Bakke, Brian A; Sadler, Joshua M; Sunkara, Naresh K; Dorgan, Kathleen M; Zhou, Zhaohui Sunny; Seley-Radtke, Katherine L

    2006-12-01

    The design, synthesis, and unexpected inhibitory activity against S-adenosyl-homocysteine (SAH) hydrolase (SAHase, EC 3.3.1.1) for a series of truncated carbocyclic pyrimidine nucleoside analogues is presented. Of the four nucleosides obtained, 10 was found to be active with a Ki value of 5.0 microM against SAHase. PMID:16904326

  3. Discovery of Tröger's base analogues as selective inhibitors against human breast cancer cell line: design, synthesis and cytotoxic evaluation.

    PubMed

    Manda, Bhaskar Reddy; Alla, Manjula; Ganji, Roopa Jones; Addlagatta, Anthony

    2014-10-30

    A library of structurally diverse Tröger's base analogues has been constructed via unusual amination of methylene bridge employing Vilsmeier-Haack conditions as well as by the incorporation of five and six membered heterocycles on the aromatic core of Tröger's base framework. The constructed structurally diverse frameworks were evaluated for their cytotoxic activities against a panel of three human cancer lines A549 (lung adenocarcinoma), MDAMB-231 (breast) and SK-N-SH (neuroblastoma). From the activity profile obtained, a redesign of Tröger's base analogues led to the construction of more potent molecular entities. The study led to development of a series of compounds with MDAMB-231 cell line specific cytotoxicity. Of the 30 compounds synthesized and evaluated, 7 compounds were found to possess cytotoxicity that is equivalent or better than standard drug doxorubicin against MDAMB-231 cell line while only one compound was found to be active against SK-N-SH cell line. PMID:25140752

  4. A novel biological role for nsLTP2 from Oriza sativa: Potential incorporation with anticancer agents, nucleosides and their analogues.

    PubMed

    Tousheh, Mojtaba; Darvishi, Fatemeh Zahra; Miroliaei, Mehran

    2015-10-01

    Development of a protein-based drug delivery system has major impact on the efficacy and bioavailability of unstable and water insoluble drugs. In the present study, the binding modes of a nonspecific lipid transfer protein (nsLTP2) from Oryza sativa with various nucleosides and analogous molecules were identified. The 3-D structure of the protein was designed and validated using modeler 9.13, Molegro virtual docker and procheck tool, respectively. The binding affinity and strength of interactions, key contributing residues and specificity toward the substrates were accomplished by computational docking and model prediction. The protein presented high affinity to acyclovir and vidarabine as purine-analogous drugs. Binding affinity is influenced by the core template and functional groups of the ligands which are structurally different cause the variation of interaction energies with nsLTP2. Nonetheless, all the evaluated analogous drugs occupy the proximity space at the nsLTP active site with high similarity in their binding modes. Our findings hold great promise for the future applications of nsLTPs in various aspects of pharmaceutical science and molecular biology. PMID:26001286

  5. Human immunodeficiency virus type 1 (HIV-1) strains selected for resistance against the HIV-1-specific [2',5'-bis-O-(tert-butyldimethylsilyl)-3'-spiro- 5''-(4''-amino-1'',2''-oxathiole-2'',2''-dioxide)]-beta-D-pentofurano syl (TSAO) nucleoside analogues retain sensitivity to HIV-1-specific nonnucleoside inhibitors.

    PubMed Central

    Balzarini, J; Karlsson, A; Vandamme, A M; Pérez-Pérez, M J; Zhang, H; Vrang, L; Oberg, B; Bäckbro, K; Unge, T; San-Félix, A

    1993-01-01

    We recently reported that a newly discovered class of nucleoside analogues--[2',5'-bis-O-(tert-butyldimethylsilyl)- 3'-spiro-5''-(4''-amino-1'',2''-oxathiole-2'',2''-dioxide)]-beta-D - pentofuranosyl derivatives of pyrimidines and purines (designated TSAO)--are highly specific inhibitors of human immunodeficiency virus type 1 (HIV-1) and targeted at the nonsubstrate binding site of HIV-1 reverse transcriptase (RT). We now find that HIV-1 strains selected for resistance against three different TSAO nucleoside derivatives retain sensitivity to the other HIV-1-specific nonnucleoside derivatives (tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione (TIBO), 1-[(2-hydroxyethoxy)methyl]-6-phenylthiothymine, nevirapine, and pyridinone L697,661, as well as to the nucleoside analogues 3'-azido-3'-deoxythymidine, ddI, ddC, and 9-(2-phosphonylmethoxyethyl)adenine. Pol gene nucleotide sequence analysis of the TSAO-resistant and -sensitive HIV-1 strains revealed a single amino acid substitution at position 138 (Glu-->Lys) in the RT of all TSAO-resistant HIV-1 strains. HIV-1 RT in which the Glu-138-->Lys substitution was introduced by site-directed mutagenesis and expressed in Escherichia coli could not be purified because of rapid degradation. However, HIV-1 RT containing the Glu-138-->Arg substitution was stable. It lost its sensitivity to the TSAO nucleosides but not to the other HIV-1-specific RT inhibitors (i.e., TIBO and pyridinone). Our findings point to a specific interaction of the 4''-amino group on the 3'-spiro-substituted ribose moiety of the TSAO nucleosides with the carboxylic acid group of glutamic acid at position 138 of HIV-1 RT. PMID:7688467

  6. B-Ring-Aryl Substituted Luotonin A Analogues with a New Binding Mode to the Topoisomerase 1-DNA Complex Show Enhanced Cytotoxic Activity

    PubMed Central

    González-Ruiz, Víctor; Pascua, Irene; Fernández-Marcelo, Tamara; Ribelles, Pascual; Bianchini, Giulia; Sridharan, Vellaisamy; Iniesta, Pilar; Ramos, M. Teresa; Olives, Ana I.; Martín, M. Antonia; Menéndez, J. Carlos

    2014-01-01

    Topoisomerase 1 inhibition is an important strategy in targeted cancer chemotherapy. The drugs currently in use acting on this enzyme belong to the family of the camptothecins, and suffer severe limitations because of their low stability, which is associated with the hydrolysis of the δ-lactone moiety in their E ring. Luotonin A is a natural camptothecin analogue that lacks this functional group and therefore shows a much-improved stability, but at the cost of a lower activity. Therefore, the development of luotonin A analogues with an increased potency is important for progress in this area. In the present paper, a small library of luotonin A analogues modified at their A and B rings was generated by cerium(IV) ammonium nitrate-catalyzed Friedländer reactions. All analogues showed an activity similar or higher than the natural luotonin A in terms of topoisomerase 1 inhibition and some compounds had an activity comparable to that of camptothecin. Furthermore, most compounds showed a better activity than luotonin A in cell cytotoxicity assays. In order to rationalize these results, the first docking studies of luotonin-topoisomerase 1-DNA ternary complexes were undertaken. Most compounds bound in a manner similar to luotonin A and to standard topoisomerase poisons such as topotecan but, interestingly, the two most promising analogues, bearing a 3,5-dimethylphenyl substituent at ring B, docked in a different orientation. This binding mode allows the hydrophobic moiety to be shielded from the aqueous environment by being buried between the deoxyribose belonging to the G(+1) guanine and Arg364 in the scissile strand and the surface of the protein and a hydrogen bond between the D-ring carbonyl and the basic amino acid. The discovery of this new binding mode and its associated higher inhibitory potency is a significant advance in the design of new topoisomerase 1 inhibitors. PMID:24830682

  7. Cytotoxicity of exfoliated transition-metal dichalcogenides (MoS2 , WS2 , and WSe2 ) is lower than that of graphene and its analogues.

    PubMed

    Teo, Wei Zhe; Chng, Elaine Lay Khim; Sofer, Zdeněk; Pumera, Martin

    2014-07-28

    Studies involving transition-metal dichalcogenides (TMDs) have been around for many decades and in recent years, many were focused on using TMDs to synthesize inorganic analogues of carbon nanotubes, fullerene, as well as graphene and its derivatives with the ultimate aim of employing these materials into consumer products. In view of this rising trend, we investigated the cytotoxicity of three common exfoliated TMDs (exTMDs), namely MoS2 , WS2 , and WSe2 , and compared their toxicological effects with graphene oxides and halogenated graphenes to find out whether these inorganic analogues of graphenes and derivatives would show improved biocompatibility. Based on the cell viability assessments using methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8) assays on human lung carcinoma epithelial cells (A549) following a 24 h exposure to varying concentrations of the three exTMDs, it was concluded that MoS2 and WS2 nanosheets induced very low cytotoxicity to A549 cells, even at high concentrations. On the other hand, WSe2 exhibited dose-dependent toxicological effects on A549 cells, reducing cell viability to 31.8 % at the maximum concentration of 400 μg mL(-1) ; the higher cytotoxicity displayed by WSe2 might be linked to the identity of the chalcogen. In comparison with graphene oxides and halogenated graphenes, MoS2 and WS2 were much less hazardous, whereas WSe2 showed similar degree of cytotoxicity. Future in-depth studies should be built upon this first work on the in vitro cytotoxicity of MoS2 and WS2 to ensure that they do not pose acute toxicity. Lastly, nanomaterial-induced interference control experiments revealed that exTMDs were capable of reacting with MTT assay viability markers in the absence of cells, but not with WST-8 assay. This suggests that the MTT assay is not suitable for measuring the cytotoxicity of exTMDs because inflated results will be obtained, giving false impressions that the materials are

  8. Osmium(II) polypyridyl polyarginine conjugate as a probe for live cell imaging; a comparison of uptake, localization and cytotoxicity with its ruthenium(II) analogue.

    PubMed

    Byrne, Aisling; Dolan, Ciarán; Moriarty, Roisin D; Martin, Aaron; Neugebauer, Ute; Forster, Robert J; Davies, Anthony; Volkov, Yuri; Keyes, Tia E

    2015-08-28

    A first investigation into the application of a luminescent osmium(ii) bipyridine complex to live cell imaging is presented. Osmium(ii) (bis-2,2-bipyridyl)-2(4-carboxylphenyl) imidazo[4,5f][1,10]phenanthroline was prepared and conjugated to octaarginine, a cell penetrating peptide. The photophysics, cell uptake and cytotoxicity of this osmium complex conjugate were performed and compared with its ruthenium analogue. Cell uptake and distribution of both ruthenium and osmium conjugates were very similar with rapid transmembrane transport of the osmium probe (complete within approx. 20 min) and dispersion throughout the cytoplasm and organelles. The near-infrared (NIR) emission of the osmium complex (λmax 726 nm) coincides well with the biological optical window and this facilitated luminescent and luminescence lifetime imaging of the cell which was well resolved from cell autofluorescence. The large Stokes shift of the emission also permitted resonance Raman mapping of the dye within CHO cells. Rather surprisingly, the osmium conjugate exhibited very low cytotoxicity when incubated both in the dark and under visible irradiation. This was attributed to the remarkable stability of this complex which was reflected by the complete absence of photo-bleaching of the complex even under extended continuous irradiation. In addition, when compared to its ruthenium analogue its luminescence was short-lived in water therefore rendering it insensitive to O2. PMID:26197944

  9. Synthesis and antiviral activity of novel 5-(1-cyanamido-2-haloethyl) and 5-(1-hydroxy(or methoxy)-2-azidoethyl) analogues of uracil nucleosides.

    PubMed

    Kumar, R; Rai, D; Sharma, S K; Saffran, H A; Blush, R; Tyrrell, D L

    2001-10-11

    A new class of 5-(1-cyanamido-2-haloethyl)-2'-deoxyuridines (4-6) and arabinouridines (7, 8) were synthesized by the regiospecific addition of halogenocyanamides (X-NHCN) to the 5-vinyl substituent of the respective 5-vinyl-2'-deoxyuridine (2) and 2'-arabinouridine (3). Reaction of 2 with sodium azide, ceric ammonium nitrate, and acetonitrile-methanol or water afforded the 5-(1-hydroxy-2-azidoethyl)-(10) and 5-(1-methoxy-2-azidoethyl)-2'-deoxyuridines (11). In vitro antiviral activities against HSV-1-TK(+) (KOS and E-377), HSV-1-TK(-), HSV-2, VZV, HCMV, and DHBV were determined. Of the newly synthesized compounds, 5-(1-cyanamido-2-iodoethyl)-2'-deoxyuridine (6) exhibited the most potent anti-HSV-1 activity, which was equipotent to acyclovir and superior to 5-ethyl-2'-deoxyuridine (EDU). In addition, it was significantly inhibitory for thymidine kinase deficient strain of HSV-1 (EC(50) = 2.3-15.3 microM). The 5-(1-cyanamido-2-haloethyl)-2'-deoxyuridines (4-6) all were approximately equipotent against HSV-2 and were approximately 1.5- and 15-fold less inhibitory for HSV-2 than EDU and acyclovir, respectively. Compounds 4-6 were all inactive against HCMV but exhibited appreciable antiviral activity against VZV. Their anti-VZV activity was similar or higher to that of EDU and approximately 5-12-fold lower than that of acyclovir. The 5-(1-cyanamido-2-haloethyl)-(7,8) analogues of arabinouridine were moderately inhibitory for VZV and HSV-1 (strain KOS), whereas compounds 10 and 11 were inactive against herpes viruses. Compounds 5 and 6 also demonstrated modest anti-hepatitis B virus activity against DHBV (EC(50) = 19.9-23.6 microM). Interestingly, the related 5-(1-azido-2-bromoethyl)-2'-deoxyuridine (1n) analogue proved to be markedly inhibitory to DHBV replication (EC(50) = 2.6-6.6 microM). All compounds investigated exhibited low host cell toxicity to several stationary and proliferating host cell lines as well as mitogen-stimulated proliferating human T lymphocytes

  10. Inhibition of Siderophore Biosynthesis in Mycobacterium tuberculosis with Nucleoside Bisubstrate Analogues: Structure–Activity Relationships of the Nucleobase Domain of 5′-O-[N-(Salicyl)sulfamoyl]adenosine

    PubMed Central

    Neres, João; Labello, Nicholas P.; Somu, Ravindranadh V.; Boshoff, Helena I.; Wilson, Daniel J.; Vannada, Jagadeshwar; Chen, Liqiang; Barry, Clifton E.; Bennett, Eric M.; Aldrich, Courtney C.

    2009-01-01

    5′-O-[N-(salicyl)sulfamoyl]adenosine (Sal-AMS) is a prototype for a new class of antitubercular agents that inhibit the aryl acid adenylating enzyme (AAAE) known as MbtA involved in biosynthesis of the mycobactins. Herein, we report the structure-based design, synthesis, biochemical, and biological evaluation of a comprehensive and systematic series of analogues, exploring the structure–activity relationship of the purine nucleobase domain of Sal-AMS. Significantly, 2-phenyl-Sal-AMS derivative 26 exhibited exceptionally potent antitubercular activity with an MIC99 under iron-deficient conditions of 0.049 µM while the N-6-cyclopropyl-Sal-AMS 16 led to improved potency and to a 64-enhancement in activity under iron-deficient conditions relative to iron-replete conditions, a phenotype concordant with the designed mechanism of action. The most potent MbtA inhibitors disclosed here display in vitro antitubercular activity superior to most current first line TB drugs, and these compounds are also expected to be useful against a wide range of pathogens that require aryl-capped siderphores for virulence. PMID:18690677

  11. Pharmacokinetics and Safety of FV-100, a Novel Oral Anti-Herpes Zoster Nucleoside Analogue, Administered in Single and Multiple Doses to Healthy Young Adult and Elderly Adult Volunteers▿

    PubMed Central

    Pentikis, Helen S.; Matson, Mark; Atiee, George; Boehlecke, Brian; Hutchins, Jeff T.; Patti, Joseph M.; Henson, Geoffrey W.; Morris, Amy

    2011-01-01

    FV-100 is the prodrug of the highly potent anti-varicella zoster virus bicyclic nucleoside analogue CF-1743. To characterize the pharmacokinetics and safety of oral FV-100, 3 randomized, double-blind, placebo-controlled clinical trials were conducted: (i) a single-ascending-dose study in 32 healthy subjects aged 18 to 55 years (100-, 200-, 400-, and 800-mg doses) with an evaluation of the food effect in the 400-mg group; (ii) a multiple-ascending-dose study in 48 subjects aged 18 to 55 years (100 mg once daily [QD], 200 mg QD, 400 mg QD, 400 mg twice a day, and 800 mg QD for 7 days); and (iii) a 2-part study in subjects aged 65 years and older with a single 400-mg dose in 15 subjects and a 400-mg QD dosing regimen for 7 days in 12 subjects. FV-100 was rapidly and extensively converted to CF-1743, the concentration of which remained above that required to reduce viral activity by 50% for the 24-hour dosing period. Renal excretion of CF-1743 was very low. A high-fat meal reduced exposure to CF-1743; a low-fat meal did not. Pharmacokinetic parameters for the elderly subjects were comparable to those for the younger subjects. FV-100 was well tolerated by all subjects. The pharmacokinetic and safety profiles of FV-100 support its continued investigation for the treatment of herpes zoster and prevention of postherpetic neuralgia with once-daily dosing and without dose modifications for elderly or renally impaired patients. PMID:21444712

  12. Nucleolipids of Canonical Purine ß‐d‐Ribo‐Nucleosides: Synthesis and Cytostatic/Cytotoxic Activities Toward Human and Rat Glioblastoma Cells

    PubMed Central

    Knies, Christine; Hammerbacher, Katharina; Kinscherf, Ralf

    2015-01-01

    Abstract We report on the synthesis of two series of canonical purine ß‐d‐ribonucleoside nucleolipids derived from inosine and adenosine, which have been characterized by elemental analyses, electrospray ionization mass spectrometry (ESI MS) as well as by 1H and 13C NMR, and pH‐dependent UV/Vis spectroscopy. A selection of the novel nucleolipids with different lipophilic moieties were first tested on their cytotoxic effect toward human macrophages. Compounds without a significant inhibitory effect on the viability of the macrophages were tested on their cytostatic/cytotoxic effect toward human astrocytoma/oligodendroglioma GOS‐3 cells as well as against the rat malignant neuroectodermal BT4Ca cell line. In order to additionally investigate the potential molecular mechanisms involved in the cytotoxic effects of the derivatives on GOS‐3 or BT4Ca cells, we evaluated the induction of apoptosis and observed the particular activity of the nucleolipid ethyl 3‐{4‐hydroxymethyl‐2‐methyl‐6‐[6‐oxo‐1‐(3,7,11‐trimethyl‐dodeca‐2,6,10‐trienyl)‐1,6‐dihydro‐purin‐9‐yl]‐tetrahydro‐furo[3,4‐d][1,3]dioxol‐2‐yl}propionate (8 c) toward both human and rat glioblastoma cell lines in vitro. PMID:27308225

  13. A review of non-nucleoside anti-hepatitis B virus agents.

    PubMed

    Zhang, Fan; Wang, Gang

    2014-03-21

    Hepatitis B Virus is the most common cause of chronic liver disease worldwide. Currently approved agents of chronic HBV infection treatment include interferon and nucleoside analogues. However, the side effects of interferon and the viral resistance of nucleoside analogues make the current treatment far from satisfactory. Therefore, new drugs with novel structures and mechanisms are needed. Recently, a number of non-nucleoside HBV inhibitors have been obtained from natural sources or prepared by synthesis/semi-synthesis. Some of them exhibited potent anti-HBV activity with novel mechanisms. These compounds provide useful information for the medicinal chemist to develop novel non-nucleoside compounds as anti-HBV agents. PMID:24549242

  14. Ovatoxin-a, A Palytoxin Analogue Isolated from Ostreopsis cf. ovata Fukuyo: Cytotoxic Activity and ELISA Detection.

    PubMed

    Pelin, Marco; Forino, Martino; Brovedani, Valentina; Tartaglione, Luciana; Dell'Aversano, Carmela; Pistocchi, Rossella; Poli, Mark; Sosa, Silvio; Florio, Chiara; Ciminiello, Patrizia; Tubaro, Aurelia

    2016-02-01

    This study provides the first evaluation of the cytotoxic effects of the recently identified palytoxin (PLTX) analog, ovatoxin-a (OVTX-a), the major toxin produced by Ostreopsis cf. ovata in the Mediterranean Sea. Its increasing detection during Ostreopsis blooms and in seafood highlights the need to characterize its toxic effects and to set up appropriate detection methods. OVTX-a is about 100 fold less potent than PLTX in reducing HaCaT cells viability (EC50 = 1.1 × 10(-9) M vs 1.8 × 10(-11) M, MTT test) in agreement with a reduced binding affinity (Kd = 1.2 × 10(-9) vs 2.7 × 10(-11) M, saturation experiments on intact cells). Similarly, OVTX-a hemolytic effect is lower than that of the reference PLTX compound. Ost-D shows the lowest cytotoxicity toward HaCaT keratinocytes, suggesting the lack of a hydroxyl group at C44 as a critical feature for PLTXs cytotoxic effects. A sandwich ELISA developed for PLTX detects also OVTX-a in a sensitive (LOD = 4.2 and LOQ = 5.6 ng/mL) and accurate manner (Bias = 0.3%), also in O. cf. ovata extracts and contaminated mussels. Although in vitro OVTX-a appears less toxic than PLTX, its cytotoxicity at nanomolar concentrations after short exposure time rises some concern for human health. The sandwich ELISA can be a viable screening method for OVTXs detection in monitoring program. PMID:26714047

  15. Synergistic cytotoxicity of sorafenib with busulfan and nucleoside analogs in human FMS-like tyrosine kinase 3 internal tandem duplications-positive acute myeloid leukemia cells.

    PubMed

    Song, Guiyun; Valdez, Benigno C; Li, Yang; Liu, Yan; Champlin, Richard E; Andersson, Borje S

    2014-11-01

    Clofarabine (Clo), fludarabine (Flu), and busulfan (Bu) are used in pretransplantation conditioning therapy for patients with myeloid leukemia. To further improve their efficacy in FMS-like tyrosine kinase 3 internal tandem duplications (FLT3-ITD)-positive acute myeloid leukemia (AML), we investigated their synergism with sorafenib (Sor). Exposure of FLT3-ITD-positive MV-4-11 and MOLM 13 cells to Bu+Clo+Flu+Sor resulted in synergistic cytotoxicity; no such synergism was observed in the FLT3-wild type THP-1 and KBM3/Bu250(6) cell lines. The drug synergism in MV-4-11 cells could be attributed to activation of DNA damage response, histone 3 modifications, inhibition of prosurvival kinases, and activation of apoptosis. Further, the phosphorylation of kinases, including FLT3, MAPK kinase (MEK), and AKT, was inhibited. The FLT3-ITD substrate STAT5 and its target gene PIM 2 product decreased when cells were exposed to Sor alone, Bu+Clo+Flu, and Bu+Clo+Flu+Sor. The level of the proapoptotic protein p53 upregulated modulator of apoptosis (PUMA) increased, whereas the level of prosurvival protein MCL-1 decreased when cells were exposed to Bu+Clo+Flu+Sor. The interactions of PUMA with MCL-1 and/or BCL-2 were enhanced when cells were exposed to Bu+Clo+Flu or Bu+Clo+Flu+Sor. The changes in the level of these proteins, which are involved in mitochondrial control of apoptosis, correlate with changes in mitochondrial membrane potential. Bu+Clo+Flu+Sor decreased mitochondrial membrane potential by 60% and caused leakage of cytochrome c, second mitochondria-derived activator of caspases (SMAC)/direct IAP Binding protein with low pI (DIABLO), and AIF from the mitochondria to the cytoplasm, caspase activation, and cell death, suggesting the activation of apoptosis. Analogous, synergistic cytotoxicity in response to Bu, Clo, Flu, and Sor was observed in mononuclear cells isolated from FLT3-ITD-positive AML patients. Although our previous studies were aimed at standardizing the

  16. Transport characteristics of mouse concentrative nucleoside transporter 1.

    PubMed

    Niitani, Miho; Nishida, Kentaro; Okuda, Hiroto; Nagai, Katsuhito; Fujimoto, Sadaki; Nagasawa, Kazuki

    2010-03-30

    Concentrative nucleoside transporter 1 (CNT1, SLC28A1) is a key molecule for determining the pharmacokinetic/pharmacodynamic profile of a candidate compound derived from a pyrimidine nucleoside, but there is no available information on the differences in the functional profile of this ortholog between man and mouse. Here, using a clone of mouse CNT1 (mCNT1), we investigated its transport characteristics and substrate specificity for synthetic nucleoside analogues, and compared them with those of human CNT1 (hCNT1). In mCNT1-transfected Cos-7 cells, pyrimidine, but not purine, nucleosides showed sodium- and concentration-dependent uptake, and uridine uptake was competitively inhibited by uridine analogues, the rank order of the inhibitory effects being 5-bromouridine>3'-deoxyuridine>2'-deoxyuridine. cis- and trans-Inhibition studies involving synthetic nucleoside drugs revealed that gemcitabine and zidovudine greatly inhibited [(3)H]uridine uptake mediated by mCNT1 in the both cases, while cytarabine and zalcitabine showed small cis-inhibitory effect, and no trans-inhibitory effect on the uptake. These results demonstrate that the transport characteristics of mCNT1 are almost the same as those of hCNT1, suggesting that mice may be a good animal model in evaluation of pyrimidine nucleoside analogues as to their applicability in human therapy. PMID:20060452

  17. Flexibility as a Strategy in Nucleoside Antiviral Drug Design.

    PubMed

    Peters, H L; Ku, T C; Seley-Radtke, K L

    2015-01-01

    As far back as Melville Wolfrom's acyclic sugar synthesis in the 1960's, synthesis of flexible nucleoside analogues have been an area of interest. This concept, however, went against years of enzyme-substrate binding theory. Hence, acyclic methodology in antiviral drug design did not take off until the discovery and subsequent FDA approval of such analogues as Acyclovir and Tenofovir. More recently, the observation that flexible nucleosides could overcome drug resistance spawned a renewed interest in the field of nucleoside drug design. The next generation of flexible nucleosides shifted the focus from the sugar moiety to the nucleobase. With analogues such as Seley-Radtke "fleximers", and Herdewijn's C5 substituted 2'-deoxyuridines, the area of base flexibility has seen great expansion. More recently, the marriage of these methodologies with acyclic sugars has resulted in a series of acyclic flex-base nucleosides with a wide range of antiviral properties, including some of the first to exhibit anti-coronavirus activity. Various flexible nucleosides and their corresponding nucleobases will be compared in this review. PMID:26282942

  18. Aqueous microwaves assisted cross-coupling reactions applied to unprotected nucleosides.

    NASA Astrophysics Data System (ADS)

    Len, Christophe; Hervé, Gwénaelle

    2015-02-01

    Nucleoside analogues have attracted much attention due to their potential biological activities. Amongst all synthetic nucleosides, C5-modified pyrimidines and C7- or C8-modified purines have mostly been prepared using palladium cross-coupling reactions and then studied as antitumoral and antiviral agents. Our objective is to focus this review on the Suzuki-Miyaura and on the Heck cross-couplings of nucleosides using microwave irradiations which are an alternative technology compatible with green chemistry and sustainable development.

  19. The SLC28 (CNT) and SLC29 (ENT) nucleoside transporter families: a 30-year collaborative odyssey.

    PubMed

    Young, James D

    2016-06-15

    Specialized nucleoside transporter (NT) proteins are required for passage of nucleosides and hydrophilic nucleoside analogues across biological membranes. Physiologic nucleosides serve as central salvage metabolites in nucleotide biosynthesis, and nucleoside analogues are used as chemotherapeutic agents in the treatment of cancer and antiviral diseases. The nucleoside adenosine modulates numerous cellular events via purino-receptor cell signalling pathways. Human NTs are divided into two structurally unrelated protein families: the SLC28 concentrative nucleoside transporter (CNT) family and the SLC29 equilibrative nucleoside transporter (ENT) family. Human CNTs are inwardly directed Na(+)-dependent nucleoside transporters found predominantly in intestinal and renal epithelial and other specialized cell types. Human ENTs mediate bidirectional fluxes of purine and pyrimidine nucleosides down their concentration gradients and are ubiquitously found in most, possibly all, cell types. Both protein families are evolutionarily old: CNTs are present in both eukaryotes and prokaryotes; ENTs are widely distributed in mammalian, lower vertebrate and other eukaryote species. This mini-review describes a 30-year collaboration with Professor Stephen Baldwin to identify and understand the structures and functions of these physiologically and clinically important transport proteins. PMID:27284054

  20. Enantioselective Intermolecular Cyclopropanations for the Synthesis of Chiral Pyrimidine Carbocyclic Nucleosides.

    PubMed

    Xie, Ming-Sheng; Zhou, Peng; Niu, Hong-Ying; Qu, Gui-Rong; Guo, Hai-Ming

    2016-09-01

    A direct route to chiral cyclopropylpyrimidine carbocyclic nucleoside analogues has been reported via highly enantioselective intermolecular cyclopropanation reactions of N1-vinylpyrimidines with α-diazoesters. With chiral ruthenium(II)-phenyloxazoline complex (2 mol %) as the catalyst, cyclopropyl pyrimidine nucleoside analogues could be obtained in good yields (71-96% yields) with high levels of diastereo- and enantioselectivities (10:1 to >20:1 dr and 96-99% ee) in 1 min. PMID:27526779

  1. Absence of testicular protection by a gonadotropin-releasing hormone analogue against cyclophosphamide-induced testicular cytotoxicity in the mouse.

    PubMed

    da Cunha, M F; Meistrich, M L; Nader, S

    1987-02-15

    Protection of testicular integrity against damage from cyclophosphamide (CY) by simultaneous treatment with a gonadotropin-releasing hormone (GnRH) analogue was reported in BALB/c mice (L.M. Glode et al., Lancet, 1: 1132-1134, 1981). This approach has been used as the basis for clinical trials in various treatment centers (D. H. Johnson et al., Blood, 65:832-836, 1985) in an attempt to prevent iatrogenic sterility in males. This study aims at duplicating the original findings and obtaining quantitative data on spermatogonial killing by CY, and possible protection by GnRH, of differentiating and stem cell spermatogonia. Mice were treated with 23 daily injections of 0.4 micrograms D-leucine-6 GnRH, and with 200 mg/kg CY on Days 8, 15, and 22. Three additional groups of mice received phosphate-buffered saline and bovine serum albumin only, GnRH only, and CY only. Animals were killed at 29 days after the last injection to determine the number of late spermatids in testicular homogenates, and at 56 days for histological measurement of the ratio of elongated spermatids to Sertoli cells in the tubules. The twenty-ninth day assay was a measure of damage to differentiating spermatogonia, whose killing results in temporary sterility. The fifty-sixth day point assay assessed damage to stem spermatogonia, whose killing results in long-term or permanent sterility. Sperm counts at 29 days were identical in saline-treated control mice and GnRH-treated mice; no sperm were present in the CY-treated mice, both with and without GnRH. Thus, killing of differentiating spermatogonia by CY is not prevented by GnRH treatment. Similarly, counts of spermatids at 56 days showed no difference between saline- and GnRH-treated groups; a reduction to approximately 40% of control counts was observed equally with CY and CY plus GnRH treatments. Since GnRH treatment did not alter spermatogonial kinetics in BALB/c mice, it is not surprising that it did not protect against CY-induced damage. Thus

  2. Medicinal chemistry of fluorinated cyclic and acyclic nucleoside phosphonates.

    PubMed

    Baszczyňski, Ondřej; Janeba, Zlatko

    2013-11-01

    The fluorine atom plays an important role in medicinal chemistry because fluorine substitution has a strong impact on the physical, chemical, and biological properties of bioactive compounds. Such fluorine modifications have also been extensively studied among the pharmaceutically important class of nucleoside phosphonates, nucleotide analogues in which the phosphate group is replaced by the enzymatically and chemically stable phosphonate moiety. The fluorinated nucleoside phosphonates abound with antiviral, antiparasitic, and anticancer properties because they are able to act as inhibitors of important enzymes of nucleoside/nucleotide metabolism. In this paper, we review the biological properties of cyclic and acyclic nucleoside phosphonates modified by the attachment of one or more fluorine atoms to various parts of the molecule, namely to nucleobases, alkylphosphonate groups, cyclic or acyclic linkers, or to prodrug moieties. PMID:23893552

  3. Mycoplasmas and cancer: focus on nucleoside metabolism

    PubMed Central

    Vande Voorde, Johan; Balzarini, Jan; Liekens, Sandra

    2014-01-01

    The standard of care for patients suffering cancer often includes treatment with nucleoside analogues (NAs). NAs are internalized by cell-specific nucleobase/nucleoside transporters and, after enzymatic activation (often one or more phosphorylation steps), interfere with cellular nucleo(s)(t)ide metabolism and DNA/RNA synthesis. Therefore, their efficacy is highly dependent on the expression and activity of nucleo(s)(t)ide-metabolizing enzymes, and alterations thereof (e.g. by down/upregulated expression or mutations) may change the susceptibility to NA-based therapy and/or confer drug resistance. Apart from host cell factors, several other variables including microbial presence may determine the metabolome (i.e. metabolite concentrations) of human tissues. Studying the diversity of microorganisms that are associated with the human body has already provided new insights in several diseases (e.g. diabetes and inflammatory bowel disease) and the metabolic exchange between tissues and their specific microbiota was found to affect the bioavailability and toxicity of certain anticancer drugs, including NAs. Several studies report a preferential colonization of tumor tissues with some mycoplasma species (mostly Mycoplasma hyorhinis). These prokaryotes are also a common source of cell culture contamination and alter the cytostatic activity of some NAs in vitro due to the expression of nucleoside-catabolizing enzymes. Mycoplasma infection may therefore bias experimental work with NAs, and their presence in the tumor microenvironment could be of significance when optimizing nucleoside-based cancer treatment. PMID:26417262

  4. Induction of Cytotoxicity in Pyridine Analogues of the Anti-metastatic Ru(III) Complex NAMI-A by Ferrocene Functionalization.

    PubMed

    Mu, Changhua; Chang, Stephanie W; Prosser, Kathleen E; Leung, Ada W Y; Santacruz, Stephanie; Jang, Thalia; Thompson, John R; Yapp, Donald T T; Warren, Jeffrey J; Bally, Marcel B; Beischlag, Timothy V; Walsby, Charles J

    2016-01-01

    A series of novel ferrocene (Fc) functionalized Ru(III) complexes was synthesized and characterized. These compounds are derivatives of the anti-metastatic Ru(III) complex imidazolium [trans-RuCl4(1H-imidazole) (DMSO-S)] (NAMI-A) and are derived from its pyridine analogue (NAMI-Pyr), with direct coupling of Fc to pyridine at the 4 or 3 positions, or at the 4 position via a two-carbon linker, which is either unsaturated (vinyl) or saturated (ethyl). Electron paramagnetic resonance (EPR) and UV-vis spectroscopic studies of the ligand exchange processes of the compounds in phosphate buffered saline (PBS) report similar solution behavior to NAMI-Pyr. However, the complex with Fc substitution at the 3 position of the coordinated pyridine shows greater solution stability, through resistance to the formation of oligomeric species. Further EPR studies of the complexes with human serum albumin (hsA) indicate that the Fc groups enhance noncoordinate interactions with the protein and help to inhibit the formation of protein-coordinated species, suggesting the potential for enhanced bioavailability. Cyclic voltammetry measurements demonstrate that the Fc groups modestly reduce the reduction potential of the Ru(III) center as compared to NAMI-Pyr, while the reduction potentials of the Fc moieties of the four compounds vary by 217 mV, with the longer linkers giving significantly lower values of E1/2. EPR spectra of the compounds with 2-carbon linkers show the formation of a high-spin Fe(III) species (S = 5/2) in PBS with a distinctive signal at g = 4.3, demonstrating oxidation of the Fe(II) ferrocene center and likely reflecting degradation products. Density functional theory calculations and paramagnetic (1)H NMR describe delocalization of spin density onto the ligands and indicate that the vinyl linker could be a potential pathway for electron transfer between the Ru and Fe centers. In the case of the ethyl linker, electron transfer is suggested to occur via an indirect

  5. CF3 Derivatives of the Anticancer Ru(III) Complexes KP1019, NKP-1339, and Their Imidazole and Pyridine Analogues Show Enhanced Lipophilicity, Albumin Interactions, and Cytotoxicity.

    PubMed

    Chang, Stephanie W; Lewis, Andrew R; Prosser, Kathleen E; Thompson, John R; Gladkikh, Margarita; Bally, Marcel B; Warren, Jeffrey J; Walsby, Charles J

    2016-05-16

    The Ru(III) complexes indazolium [trans-RuCl4(1H-indazole)2] (KP1019) and sodium [trans-RuCl4(1H-indazole)2] (NKP-1339) are leading candidates for the next generation of metal-based chemotherapeutics. Trifluoromethyl derivatives of these compounds and their imidazole and pyridine analogues were synthesized to probe the effect of ligand lipophilicity on the pharmacological properties of these types of complexes. Addition of CF3 groups also provided a spectroscopic handle for (19)F NMR studies of ligand exchange processes and protein interactions. The lipophilicities of the CF3-functionalized compounds and their unsubstituted parent complexes were quantified by the shake-flask method to give the distribution coefficient D at pH 7.4 (log D7.4). The solution behavior of the CF3-functionalized complexes was characterized in phosphate-buffered saline (PBS) using (19)F NMR, electron paramagnetic resonance (EPR), and UV-vis spectroscopies. These techniques, along with fluorescence competition experiments, were also used to characterize interactions with human serum albumin (HSA). From these studies it was determined that increased lipophilicity correlates with reduced solubility in PBS but enhancement of noncoordinate interactions with hydrophobic domains of HSA. These protein interactions improve the solubility of the complexes and inhibit the formation of oligomeric species. EPR measurements also demonstrated the formation of HSA-coordinated species with longer incubation. (19)F NMR spectra show that the trifluoromethyl complexes release axial ligands in PBS and in the presence of HSA. In vitro testing showed that the most lipophilic complexes had the greatest cytotoxic activity. Addition of CF3 groups enhances the activity of the indazole complex against A549 nonsmall cell lung carcinoma cells. Furthermore, in the case of the pyridine complexes, the parent compound was inactive against the HT-29 human colon carcinoma cell line but showed strong cytotoxicity with CF3

  6. Multicomponent reactions in nucleoside chemistry

    PubMed Central

    Buchowicz, Włodzimierz

    2014-01-01

    Summary This review covers sixty original publications dealing with the application of multicomponent reactions (MCRs) in the synthesis of novel nucleoside analogs. The reported approaches were employed for modifications of the parent nucleoside core or for de novo construction of a nucleoside scaffold from non-nucleoside substrates. The cited references are grouped according to the usually recognized types of the MCRs. Biochemical properties of the novel nucleoside analogs are also presented (if provided by the authors). PMID:25161730

  7. Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides

    PubMed Central

    Ren, Hang; Hatala, Paul J; Stevens, William C; He, Baicheng

    2015-01-01

    Summary A unified synthetic strategy accessing novel 3'-fluorinated purine nucleoside derivatives and their biological evaluation were achieved. Novel 3’-fluorinated analogues were constructed from a common 3’-deoxy-3’-fluororibofuranose intermediate. Employing Suzuki and Stille cross-coupling reactions, fifteen 3’-fluororibose purine nucleosides 1–15 and eight 3’-fluororibose 2-chloro/2-aminopurine nucleosides 16–23 with various substituents at position 6 of the purine ring were efficiently synthesized. Furthermore, 3’-fluorine analogs of natural products nebularine and 6-methylpurine riboside were constructed via our convergent synthetic strategy. Synthesized nucleosides were tested against HT116 (colon cancer) and 143B (osteosarcoma cancer) tumor cell lines. We have demonstrated 3’-fluorine purine nucleoside analogues display potent tumor cell growth inhibition activity at sub- or low micromolar concentration. PMID:26734098

  8. A metal-containing nucleoside that possesses both therapeutic and diagnostic activity against cancer.

    PubMed

    Choi, Jung-Suk; Maity, Ayan; Gray, Thomas; Berdis, Anthony J

    2015-04-10

    Nucleoside transport is an essential process that helps maintain the hyperproliferative state of most cancer cells. As such, it represents an important target for developing diagnostic and therapeutic agents that can effectively detect and treat cancer, respectively. This report describes the development of a metal-containing nucleoside designated Ir(III)-PPY nucleoside that displays both therapeutic and diagnostic properties against the human epidermal carcinoma cell line KB3-1. The cytotoxic effects of Ir(III)-PPY nucleoside are both time- and dose-dependent. Flow cytometry analyses validate that the nucleoside analog causes apoptosis by blocking cell cycle progression at G2/M. Fluorescent microscopy studies show rapid accumulation in the cytoplasm within 4 h. However, more significant accumulation is observed in the nucleus and mitochondria after 24 h. This localization is consistent with the ability of the metal-containing nucleoside to influence cell cycle progression at G2/M. Mitochondrial depletion is also observed after longer incubations (Δt ∼48 h), and this effect may produce additional cytotoxic effects. siRNA knockdown experiments demonstrate that the nucleoside transporter, hENT1, plays a key role in the cellular entry of Ir(III)-PPY nucleoside. Collectively, these data provide evidence for the development of a metal-containing nucleoside that functions as a combined therapeutic and diagnostic agent against cancer. PMID:25713072

  9. Functionalization of 2H-1,2,3-Triazole C-Nucleoside Template via N(2) Selective Arylation.

    PubMed

    Lopes, Alexandra Basilio; Wagner, Patrick; de Souza, Rodrigo Octavio Mendonça Alves; Germain, Nadège Lubin; Uziel, Jacques; Bourguignon, Jean-Jacques; Schmitt, Martine; Miranda, Leandro S M

    2016-06-01

    C-Nucleosides are an underexplored and important class of nucleosides with antiviral and anticancer activity. In addition, triazole heterocycles are well employed as a strategy to modify nucleobase in nucleoside analogues, although rare examples were described for triazoyl C-nucleosides. N(2)-Aryl-1,2,3-triazole C-nucleoside compounds that could be obtained by selective 1,2,3-triazole heterocycle N(2) arylation in 1-β-d-ribofuranosyl-2H-1,2,3-triazole substrate were designed in this study. The optimized condition used AdBrettPhos/[PdCl(allyl)]2 as the catalyst system. This transformation was accomplished by aryl halides bearing an electron donor and withdrawing groups, as well as by heterocyclic halides in good to excellent yields. The transformation developed in this study represents a significant contribution to the nucleoside field, once it allows for the synthesis of unexplored scaffolds through selective functionalization of triazole nucleosides. PMID:27166644

  10. Pseudocyanides of sanguinarine and chelerythrine and their series of structurally simple analogues as new anticancer lead compounds: Cytotoxic activity, structure-activity relationship and apoptosis induction.

    PubMed

    Cao, Fang-Jun; Yang, Rui; Lv, Chao; Ma, Qun; Lei, Ming; Geng, Hui-Ling; Zhou, Le

    2015-01-25

    6-Cyano dihydrosanguinarine (CNS) and 6-cyano dihydrochelerythrine (CNC) are respectively artificial derivatives of sanguinarine and chelerythrine, two anticancer quaternary benzo[c]phenanthridine alkaloids (QBAs) while 1-cyano-2-aryl-1,2,3,4-tetrahydroisoquinolines (CATHIQs) are a class of structurally simple analogues of CNS or CNC. This study investigated the inhibition activity of CNS, CNC and CATHIQs on cancer cells, apoptosis induction as well as their preliminary SAR. The results showed that CNS and 18 out of CATHIQs showed IC50 values of 0.53 and 0.62-2.24μM against NB4 and 1.53 and 2.99-11.17μM against MKN-45 cells, respectively, superior to a standard anticancer drug cis-platinum with IC50 of 2.39 and 11.36μM. CNC showed a higher activity against NB4 cells (IC50=1.85μM) and a moderate activity against MKN-45 cells (IC50=12.72μM). Among all CATHIQs, 2 and 17 gave the highest activity against NB4 cells and MKN-45 cells (IC50=0.62 and 2.99μM), respectively. DAPI staining, AO/EB staining and ultrastructure analysis of cells demonstrated that CATHIQs were able to induce apoptosis of the cells in a concentration-dependent manner. SAR showed that substitution patterns on the N-aromatic ring significantly influenced the activity of CATHIQs. The general trend was that the introduction of electron-withdrawing substituents like halogen atom, nitro, trifluoromethyl led to a significant improvement of the activity, while the presence of electron-donating groups like methyl, methoxyl caused a reduction of the activity. In most cases, the 2' site was the most favorable substitution position for the improvement of the activity. Thus, the present results strongly suggested that QBA-type pseudocyanides may serve as potential alternatives of anticancer QBAs while CATHIQs should be a class of promising lead compounds for the development of new QBA-like-type anticancer drugs. CNS exhibited the highest cytotoxicities with IC50 values of 0.53μM on NB4 cells and 1.53

  11. Expedient and generic synthesis of imidazole nucleosides by enzymatic transglycosylation.

    PubMed

    Vichier-Guerre, S; Dugué, L; Bonhomme, F; Pochet, S

    2016-04-14

    A straightforward route to original imidazole-based nucleosides that makes use of an enzymatic N-transglycosylation step is reported in both the ribo- and deoxyribo-series. To illustrate the scope of this approach, a diverse set of 4-aryl and 4-heteroaryl-1H-imidazoles featuring variable sizes and hydrogen-bonding patterns was prepared using a microwave-assisted Suzuki-Miyaura cross-coupling reaction. These imidazole derivatives were examined as possible substrates for the nucleoside 2'-deoxyribosyltransferase from L. leichmannii and the purine nucleoside phosphorylase from E. coli. The optimum transglycosylation conditions, including the use of co-adjuvants to address solubility issues, were defined. Enzymatic conversion of 4-(hetero)arylimidazoles to 2'-deoxyribo- or ribo-nucleosides proceeded in good to high conversion yields, except bulky hydrophobic imidazole derivatives. Nucleoside deoxyribosyltransferase of class II was found to convert the widest range of functionalized imidazoles into 2'-deoxyribonucleosides and was even capable of bis-glycosylating certain heterocyclic substrates. Our findings should enable chemoenzymatic access to a large diversity of flexible nucleoside analogues as molecular probes, drug candidates and original building blocks for synthetic biology. PMID:26986701

  12. Mdm2 inhibition confers protection of p53-proficient cells from the cytotoxic effects of Wee1 inhibitors

    PubMed Central

    Dobbelstein, Matthias

    2015-01-01

    Pharmacological inhibition of the cell cycle regulatory kinase Wee1 represents a promising strategy to eliminate cancer cells. Wee1 inhibitors cooperate with chemotherapeutics, e. g. nucleoside analogues, pushing malignant cells from S phase towards premature mitosis and death. However, considerable toxicities are observed in preclinical and clinical trials. A high proportion of tumor cells can be distinguished from all other cells of a patient's body by inactivating mutations in the tumor suppressor p53. Here we set out to develop an approach for the selective protection of p53-proficient cells against the cytotoxic effects of Wee1 inhibitors. We pretreated such cells with Nutlin-3a, a prototype inhibitor of the p53-antagonist Mdm2. The resulting transient cell cycle arrest effectively increased the survival of cells that were subsequently treated with combinations of the Wee1 inhibitor MK-1775 and/or the nucleoside analogue gemcitabine. In this constellation, Nutlin-3a reduced caspase activation and diminished the phosphorylation of Histone 2AX, an indicator of the DNA damage response. Both effects were strictly dependent on the presence of p53. Moreover, Nutlin pre-treatment reduced the fraction of cells that were undergoing premature mitosis in response to Wee1 inhibition. We conclude that the pre-activation of p53 through Mdm2 antagonists serves as a viable option to selectively protect p53-proficient cells against the cytotoxic effects of Wee1 inhibitors, especially when combined with a nucleoside analogue. Thus, Mdm2 antagonists might prove useful to avoid unwanted side effects of Wee1 inhibitors. On the other hand, when a tumor contains wild type p53, care should be taken not to induce its activity before applying Wee1 inhibitors. PMID:26431163

  13. Induction of cytotoxic peritoneal exudate cells by T-cell immune adjuvants of the beta(1 leads to 3) glucan-type lentinan and its analogues.

    PubMed Central

    Hamuro, J; Röllinghoff, M; Wagner, H

    1980-01-01

    Eight distinct polysaccharides (PS) of beta(1 leads to 3) glucan type were tested for their capacity to render murine peritoneal exudate cells (PEC) cytotoxic. After intraperitoneal injection of lentinan, pachymaran and HE-pachyman 3 and 4 highly cytotoxic PEC were induced. Pachyman and HE-pachyman 1 and 2 were of moderate effect, whereas CM-pachymaran and HE-pachyman 3 and 4, highly cytotoxic PEC were induced. Pachyman and HE-pachymacrophages. The induction of PEC-dependent cytotoxicity exhibited a strict dose relationship. Optimal administration of PS resulted in the induction of cytotoxicity, which persisted for more than 25 days. Surprisingly, none of the PS tested was capable of rendering normal or thioglycollate-induced PEC cytoxic under in vitro conditions. It is suggested that the capacity of PS to render in vivo macrophages cytotoxic is related to the potency of these PS to activate the alternative pathway of complement system (APC) in so far as C3b may be the essential component required to render macrophages cytotoxic. PMID:6966608

  14. [Two novel fixed formulations of nucleoside analogues (tenofovir-emtricitabine, and abacavir-lamivudine). Prospective, open study on clinical practice and therapeutic perspectives, in patients naïve and in subjects pre-treated with antiretrovirals].

    PubMed

    Manfredi, Roberto; Calza, Leonardo

    2008-10-01

    The introduction of novel, fixed nucleoside-nucleotide reverse transcriptase inhibitor (NRTI) combinations (tenofovir-emtricitabine, and abacavir-lamivudine), expanded the spectrum of available formulations and increased patient's adherence. A prospective survey of the open-label use of these two fixed combinations was performed in 158 patients belonging to our single-centre cohort of over 1,000 HIV-infected subjects enrolled in the last 18 months, and followed for at least 12 months. During the last 18 months, 95 consecutive, evaluable patients (60.1%) received for the first time tenofovir-emtricitabine, or abacavir-lamivudine (63 patients, 39.9%), and were followed for at least 12 months. A major role seems to be played by tenofovir-emtricitabine in first-line treatments (preferably among "compact" regimens based on efavirenz), while the proportionally increased abacavir-lamivudine prescription to pre-treated patients is mostly attributable to the different genetic barrier of abacavir (often associated with boosted protease inhibitors, in this last patient group). The present availability to two more fixed NRTI combinations favored by their single pill, once-daily administration encourages randomized, controlled "head to head" studies in both first-line and experienced patients, in order to better exploit and target their therapeutic potential. PMID:19040127

  15. Deciphering the Structural Requirements of Nucleoside Bisubstrate Analogues for Inhibition of MbtA in Mycobacterium tuberculosis: A FB-QSAR Study and Combinatorial Library Generation for Identifying Potential Hits.

    PubMed

    Maganti, Lakshmi; Das, Sanjit Kumar; Mascarenhas, Nahren Manuel; Ghoshal, Nanda

    2011-10-01

    The re-emergence of tuberculosis infections, which are resistant to conventional drug therapy, has steadily risen in the last decade. Inhibitors of aryl acid adenylating enzyme known as MbtA, involved in siderophore biosynthesis in Mycobacterium tuberculosis, are being explored as potential antitubercular agents. The ability to identify fragments that interact with a biological target is a key step in fragment based drug design (FBDD). To expand the boundaries of quantitative structure activity relationship (QSAR) paradigm, we have proposed a Fragment Based QSAR methodology, referred here in as FB-QSAR, for deciphering the structural requirements of a series of nucleoside bisubstrate analogs for inhibition of MbtA, a key enzyme involved in siderophore biosynthetic pathway. For the development of FB-QSAR models, statistical techniques such as stepwise multiple linear regression (SMLR), genetic function approximation (GFA) and GFAspline were used. The predictive ability of the generated models was validated using different statistical metrics, and similarity-based coverage estimation was carried out to define applicability boundaries. To aid the creation of novel antituberculosis compounds, a bioisosteric database was enumerated using the combichem approach endorsed mining in a lead-like chemical space. The generated library was screened using an integrated in-silico approach and potential hits identified. PMID:27468106

  16. Synthesis of α-L-threose nucleoside phosphonates via regioselective sugar protection.

    PubMed

    Dumbre, Shrinivas G; Jang, Mi-Yeon; Herdewijn, Piet

    2013-07-19

    A new synthesis route to α-L-threose nucleoside phosphonates via 2-O and 3-O selectively protected L-threose is developed. The key intermediates 2-O-benzoyl-L-threonolactone and 1-O-acetyl-2-O-benzoyl-3-O-t-butyldiphenylsilyl-L-threofuranose were functionalized to synthesize 2'-deoxy-2'-fluoro- and 3'-C-ethynyl L-threose 3'-O-phosphonate nucleosides. The key intermediates developed are important intermediates for the synthesis of new L-threose-based nucleoside analogues, TNA phosphoramidites, and TNA triphosphates. PMID:23822647

  17. Flow cytomeric measurement of DNA and incorporated nucleoside analogs

    DOEpatents

    Dolbeare, Frank A.; Gray, Joe W.

    1989-01-01

    A method is provided for simultaneously measuring total cellular DNA and incorporated nucleoside analog. The method entails altering the cellular DNA of cells grown in the presence of a nucleoside analog so that single stranded and double stranded portions are present. Separate stains are used against the two portions. An immunochemical stain is used against the single stranded portion to provide a measure of incorporated nucleoside analog, and a double strand DNA-specific stain is used against the double stranded portion to simultaneously provide a measure of total cellular DNA. The method permits rapid flow cytometric analysis of cell populations, rapid identification of cycling and noncycling subpopulations, and determination of the efficacy of S phase cytotoxic anticancer agents.

  18. Nucleosides Accelerate Inflammatory Osteolysis, Acting as Distinct Innate Immune Activators

    PubMed Central

    Pan, George; Zheng, Rui; Yang, Pingar; Li, Yao; Clancy, John P.; Liu, Jianzhong; Feng, Xu; Garber, David A; Spearman, Paul; McDonald, Jay M

    2015-01-01

    The innate immune system and its components play an important role in the pathogenesis of inflammatory bone destruction. Blockade of inflammatory cytokines does not completely arrest bone erosion, suggesting that other mediators also may be involved in osteolysis. Previously we showed that nucleosides promote osteoclastogenesis and bone-resorption activity in the presence of receptor activator for nuclear factor κB ligand (RANKL) in vitro. The studies described here further demonstrate that selected nucleosides and nucleoside analogues accelerate bone destruction in mice immunized with collagen II alone (CII) but also further enhance bone erosion in mice immunized by collagen II plus complete Freund's adjuvant (CII + CFA). Abundant osteoclasts are accumulated in destructive joints. These data indicate that nucleosides act as innate immune activators distinct from CFA, synergistically accelerating osteoclast formation and inflammatory osteolysis. The potential roles of the surface triggering receptor expressed on myeloid cells (TREM) and the intracellular inflammasome in nucleoside-enhanced osteoclastogenesis have been studied. These observations provide new insight into the pathogenesis and underlying mechanism of bone destruction in inflammatory autoimmune osteoarthritis. PMID:21472777

  19. Purine nucleoside modulation of functions of human lymphocytes.

    PubMed

    Priebe, T; Platsoucas, C D; Seki, H; Fox, F E; Nelson, J A

    1990-09-01

    The accumulation of endogenous substrates in patients with adenosine deaminase deficiency or purine nucleoside phosphorylase deficiency is believed to be responsible for the immunodeficiency observed in these patients. To identify the lymphocyte populations that are most susceptible to these substrates, we investigated the effect of their nucleoside analogs on a number of T and B cell functions of human lymphocytes. We found that tubercidin (Tub), 2-chloro 2'deoxyadenosine (2CldA), 2-fluoro adenine arabinoside-5'phosphate (FaraAMP), and 9-beta-D-arabinosyl guanine (AraGua) inhibited the proliferative responses of human peripheral blood mononuclear cells (PBMC) to polyclonal activators (PHA, OKT3 mab) or to allogeneic PBMC in mixed lymphocyte cultures (MLC). Addition of recombinant IL-2 from the beginning of the culture did not alter the inhibition by Tub of the proliferative responses of PBMC. These purine nucleoside analogs also inhibited the proliferative responses of purified human peripheral blood CD4+ and CD8+ T cells to PHA and of purified B cells to SAC. The concentrations of these nucleosides required to achieve a given degree of inhibition of proliferative responses of T lymphocyte subpopulations or B cells was similar, suggesting that these analogs do not exhibit any selectivity for these purified lymphocyte populations. Tub and FaraAMP, respectively, inhibited and enhanced, at the effector phase, both NK cytotoxicity and specific T cell-mediated cytotoxicity. In contrast to these findings, LAK cytotoxicity at the effector phase was not significantly inhibited by Tub, and was not enhanced by FaraAMP. Both analogs inhibited rIL-2-induced proliferative responses of PBMC, but did not affect the generation of LAK cytotoxicity (induction phase) against the K562 targets when added at the beginning of the culture. This suggests that DNA synthesis is not required for LAK cell induction. Both Tub and FaraAMP inhibited immunoglobulin production (IgG and IgM) by

  20. Recent availability of two novel, fixed formulations of antiretroviral nucleoside analogues: a 12-month prospective, open-label survey of their practical use and therapeutic perspectives in antiretroviral-naive and -experienced patients.

    PubMed

    Manfredi, Roberto; Calza, Leonardo

    2008-04-01

    The recent introduction of novel, fixed nucleoside-nucleotide reverse transcriptase inhibitor (NRTI) combinations (tenofovir-emtricitabine, and abacavir-lamivudine) expanded the spectrum of available formulations and concurrently increased patients' adherence levels. A prospective survey of the open-label use of these two fixed combinations was performed in 158 patients belonging to our single-center cohort of more than 1,000 HIV-infected subjects enrolled in the last 18 months, and followed for at least 12 months. During the last 18 months, 95 consecutive, evaluable patients (60.1%) received for the first time tenofovir-emtricitabine, or abacavir-lamivudine (63 patients, 39.9%), and were followed for at least 12 months with periodic clinical and laboratory examinations. Among the 53 evaluable patients who were naïve to all antiretrovirals, tenofovir-emtricitabine has been given to 42 subjects (79.2%), mostly associated with efavirenz (26 cases), or different boosted protease inhibitors (16 subjects), whereas abacavir-lamivudine was administered to 11 patients (in 10 cases of 11, together with boosted protease inhibitors). In the remaining 105 patients, tenofovir-emtricitabine or abacavir-lamivudine therapy represented a switch from a prior combination antiretroviral regimen, and was predominantly associated with boosted protease inhibitors (61 patients), versus efavirenz or nevirapine (26 cases), or other drug combinations containing protease inhibitors (the remaining 18 patients). Among the 105 pretreated patients, the prescription of tenofovir-emtricitabine (53 patients) was as frequent as that of abacavir-lamivudine (52 cases), and the therapeutic change was primarily prompted by toxicity or poor tolerability (59 patients), followed by therapeutic failure and viral resistance (46 cases as a whole), and always encompassed a regimen simplification also. Both fixed combinations were well tolerated, and an adherence rate more than 90% was estimated among evaluable

  1. Nucleoside Inhibitors of Zika Virus.

    PubMed

    Eyer, Luděk; Nencka, Radim; Huvarová, Ivana; Palus, Martin; Joao Alves, Maria; Gould, Ernest A; De Clercq, Erik; Růžek, Daniel

    2016-09-01

    There is growing evidence that Zika virus (ZIKV) can cause devastating infant brain defects and other neurological disorders in humans. However, no specific antiviral therapy is available at present. We tested a series of 2'-C- or 2'-O-methyl-substituted nucleosides, 2'-C-fluoro-2'-C-methyl-substituted nucleosides, 3'-O-methyl-substituted nucleosides, 3'-deoxynucleosides, derivatives with 4'-C-azido substitution, heterobase-modified nucleosides, and neplanocins for their ability to inhibit ZIKV replication in cell culture. Antiviral activity was identified when 2'-C-methylated nucleosides were tested, suggesting that these compounds might represent promising lead candidates for further development of specific antivirals against ZIKV. PMID:27234417

  2. Synthesis, DNA Polymerase Incorporation, and Enzymatic Phosphate Hydrolysis of Formamidopyrimidine Nucleoside Triphosphates

    PubMed Central

    Imoto, Shuhei; Patro, Jennifer N.; Jiang, Yu Lin; Oka, Natsuhisa; Greenberg, Marc M.

    2007-01-01

    The nucleoside triphosphates of N6-(2-deoxy-α,β-d-erythro-pentofuranosyl)-2,6-diamino-4-hydroxy-5-formamidopyrimidine (Fapy·dGTP) and its C-nucleoside analogue (β-C-Fapy·dGTP) were synthesized. The lability of the formamide group required that nucleoside triphosphate formation be carried out using an umpolung strategy in which pyrophosphate was activated toward nucleophilic attack. The Klenow fragment of DNA polymerase I from Escherichia coli accepted Fapy·dGTP and β-C-Fapy·dGTP as substrates much less efficiently than it did dGTP. Subsequent extension of a primer containing either modified nucleotide was less affected compared to when the native nucleotide is present at the 3′-terminus. The specificity constants are sufficiently large that nucleoside triphosphate incorporation could account for the level of Fapy·dG observed in cells if 1% of the dGTP pool is converted to Fapy·dGTP. Similarly, polymerase-mediated introduction of β-C-Fapy·dG could be useful for incorporating useful amounts of this nonhydrolyzable analogue for use as an inhibitor of base excision repair. The kinetic viability of these processes is enhanced by inefficient hydrolysis of Fapy·dGTP and β-C-Fapy·dGTP by MutT, the E. coli enzyme that releases pyrophosphate and the corresponding nucleoside monophosphate upon reaction with structurally related nucleoside triphosphates. PMID:17090045

  3. The Role of Flexible Loops in Folding, Trafficking and Activity of Equilibrative Nucleoside Transporters

    PubMed Central

    Aseervatham, Jaya; Tran, Lucky; Machaca, Khaled; Boudker, Olga

    2015-01-01

    Equilibrative nucleoside transporters (ENTs) are integral membrane proteins, which reside in plasma membranes of all eukaryotic cells and mediate thermodynamically downhill transport of nucleosides. This process is essential for nucleoside recycling, and also plays a key role in terminating adenosine-mediated cellular signaling. Furthermore, ENTs mediate the uptake of many drugs, including anticancer and antiviral nucleoside analogues. The structure and mechanism, by which ENTs catalyze trans-membrane transport of their substrates, remain unknown. To identify the core of the transporter needed for stability, activity, and for its correct trafficking to the plasma membrane, we have expressed human ENT deletion mutants in Xenopus laevis oocytes and determined their localization, transport properties and susceptibility to inhibition. We found that the carboxyl terminal trans-membrane segments are essential for correct protein folding and trafficking. In contrast, the soluble extracellular and intracellular loops appear to be dispensable, and must be involved in the fine-tuning of transport regulation. PMID:26406980

  4. The Role of Flexible Loops in Folding, Trafficking and Activity of Equilibrative Nucleoside Transporters.

    PubMed

    Aseervatham, Jaya; Tran, Lucky; Machaca, Khaled; Boudker, Olga

    2015-01-01

    Equilibrative nucleoside transporters (ENTs) are integral membrane proteins, which reside in plasma membranes of all eukaryotic cells and mediate thermodynamically downhill transport of nucleosides. This process is essential for nucleoside recycling, and also plays a key role in terminating adenosine-mediated cellular signaling. Furthermore, ENTs mediate the uptake of many drugs, including anticancer and antiviral nucleoside analogues. The structure and mechanism, by which ENTs catalyze trans-membrane transport of their substrates, remain unknown. To identify the core of the transporter needed for stability, activity, and for its correct trafficking to the plasma membrane, we have expressed human ENT deletion mutants in Xenopus laevis oocytes and determined their localization, transport properties and susceptibility to inhibition. We found that the carboxyl terminal trans-membrane segments are essential for correct protein folding and trafficking. In contrast, the soluble extracellular and intracellular loops appear to be dispensable, and must be involved in the fine-tuning of transport regulation. PMID:26406980

  5. Lipophilic prodrugs of nucleoside triphosphates as biochemical probes and potential antivirals

    PubMed Central

    Gollnest, Tristan; de Oliveira, Thiago Dinis; Schols, Dominique; Balzarini, Jan; Meier, Chris

    2015-01-01

    The antiviral activity of nucleoside reverse transcriptase inhibitors is often limited by ineffective phosphorylation. We report on a nucleoside triphosphate (NTP) prodrug approach in which the γ-phosphate of NTPs is bioreversibly modified. A series of TriPPPro-compounds bearing two lipophilic masking units at the γ-phosphate and d4T as a nucleoside analogue are synthesized. Successful delivery of d4TTP is demonstrated in human CD4+ T-lymphocyte cell extracts by an enzyme-triggered mechanism with high selectivity. In antiviral assays, the compounds are potent inhibitors of HIV-1 and HIV-2 in CD4+ T-cell (CEM) cultures. Highly lipophilic acyl residues lead to higher membrane permeability that results in intracellular delivery of phosphorylated metabolites in thymidine kinase-deficient CEM/TK− cells with higher antiviral activity than the parent nucleoside. PMID:26503889

  6. N-Branched acyclic nucleoside phosphonates as monomers for the synthesis of modified oligonucleotides.

    PubMed

    Hocková, Dana; Rosenbergová, Šárka; Ménová, Petra; Páv, Ondřej; Pohl, Radek; Novák, Pavel; Rosenberg, Ivan

    2015-04-21

    Protected N-branched nucleoside phosphonates containing adenine and thymine bases were prepared as the monomers for the introduction of aza-acyclic nucleotide units into modified oligonucleotides. The phosphotriester and phosphoramidite methods were used for the incorporation of modified and natural units, respectively. The solid phase synthesis of a series of nonamers containing one central modified unit was successfully performed in both 3'→5' and 5'→3' directions. Hybridization properties of the prepared oligoribonucleotides and oligodeoxyribonucleotides were evaluated. The measurement of thermal characteristics of the complexes of modified nonamers with the complementary strand revealed a considerable destabilizing effect of the introduced units. We also examined the substrate/inhibitory properties of aza-acyclic nucleoside phosphono-diphosphate derivatives (analogues of nucleoside triphosphates) but neither inhibition of human and bacterial DNA polymerases nor polymerase-mediated incorporation of these triphosphate analogues into short DNA was observed. PMID:25766752

  7. Structure of nucleoside diphosphate kinase from pacific shrimp (Litopenaeus vannamei) in binary complexes with purine and pyrimidine nucleoside diphosphates

    PubMed Central

    López-Zavala, Alonso A.; Quintero-Reyes, Idania E.; Carrasco-Miranda, Jesús S.; Stojanoff, Vivian; Weichsel, Andrzej; Rudiño-Piñera, Enrique; Sotelo-Mundo, Rogerio R.

    2014-01-01

    Nucleoside diphosphate kinase (NDK; EC 2.7.4.6) is an enzyme that catalyzes the third phosphorylation of nucleoside diphosphates, leading to nucleoside triphosphates for DNA replication. Expression of the NDK from Litopenaeus vannamei (LvNDK) is known to be regulated under viral infection. Also, as determined by isothermal titration calorimetry, LvNDK binds both purine and pyrimidine deoxynucleoside diphosphates with high binding affinity for dGDP and dADP and with no heat of binding interaction for dCDP [Quintero-Reyes et al. (2012 ▶), J. Bioenerg. Biomembr. 44, 325–331]. In order to investigate the differences in selectivity, LvNDK was crystallized as binary complexes with both acceptor (dADP and dCDP) and donor (ADP) phosphate-group nucleoside diphosphate substrates and their structures were determined. The three structures with purine or pyrimidine nucleotide ligands are all hexameric. Also, the binding of deoxy or ribonucleotides is similar, as in the former a water molecule replaces the hydrogen bond made by Lys11 to the 2′-hydroxyl group of the ribose moiety. This allows Lys11 to maintain a catalytically favourable conformation independently of the kind of sugar found in the nucleotide. Because of this, shrimp NDK may phosphorylate nucleotide analogues to inhibit the viral infections that attack this organism. PMID:25195883

  8. Structure of nucleoside diphosphate kinase from pacific shrimp (Litopenaeus vannamei) in binary complexes with purine and pyrimidine nucleoside diphosphates.

    PubMed

    López-Zavala, Alonso A; Quintero-Reyes, Idania E; Carrasco-Miranda, Jesús S; Stojanoff, Vivian; Weichsel, Andrzej; Rudiño-Piñera, Enrique; Sotelo-Mundo, Rogerio R

    2014-09-01

    Nucleoside diphosphate kinase (NDK; EC 2.7.4.6) is an enzyme that catalyzes the third phosphorylation of nucleoside diphosphates, leading to nucleoside triphosphates for DNA replication. Expression of the NDK from Litopenaeus vannamei (LvNDK) is known to be regulated under viral infection. Also, as determined by isothermal titration calorimetry, LvNDK binds both purine and pyrimidine deoxynucleoside diphosphates with high binding affinity for dGDP and dADP and with no heat of binding interaction for dCDP [Quintero-Reyes et al. (2012), J. Bioenerg. Biomembr. 44, 325-331]. In order to investigate the differences in selectivity, LvNDK was crystallized as binary complexes with both acceptor (dADP and dCDP) and donor (ADP) phosphate-group nucleoside diphosphate substrates and their structures were determined. The three structures with purine or pyrimidine nucleotide ligands are all hexameric. Also, the binding of deoxy or ribonucleotides is similar, as in the former a water molecule replaces the hydrogen bond made by Lys11 to the 2'-hydroxyl group of the ribose moiety. This allows Lys11 to maintain a catalytically favourable conformation independently of the kind of sugar found in the nucleotide. Because of this, shrimp NDK may phosphorylate nucleotide analogues to inhibit the viral infections that attack this organism. PMID:25195883

  9. Microbial transformation of nucleosides

    NASA Technical Reports Server (NTRS)

    Lamba, S. S.

    1979-01-01

    A study involving the use of coulter counter in studying the effects of neomycin on E. coli, S. aureus and A. aerogenes was completed. The purpose of this was to establish proper technique for enumeration of cells per ml. It was found that inhibitory effects on growth of E. coli and A. aerogenes, both gram negative organisms, were directly related to the concentration of neomycin used. However, in case S. aureus, a gram positive organism, a decreased inhibition was noted at higher concentrations. A paper entitled, Use of Coulter Counter in Studying Effect of Drugs on Cells in Culture 1 - Effects of Neomycin on E. coli, S. aureus and A. aerogenes, is attached in the appendix. Laboratory procedures were also established to study the effects of nucleoside antibiotic cordycepin on He La cell grown in suspension cultures.

  10. [Purine nucleoside phosphorylase].

    PubMed

    Pogosian, L G; Akopian, Zh I

    2013-01-01

    Purine nucleoside phosphorylase (PNP) is one of the most important enzymes of the purine metabolism, wich promotes the recycling of purine bases. Nowadays is the actual to search for effective inhibitors of this enzyme which is necessary for creation T-cell immunodeficient status of the organism in the organs and tissues transplantation, and chemotherapy of a number pathologies as well. For their successful practical application necessary to conduct in-depth and comprehensive study of the enzyme, namely a structure, functions, and an affinity of the reaction mechanism. In the review the contemporary achievements in the study of PNP from various biological objects are presented. New data describing the structure of PNP are summarised and analysed. The physiological role of the enzyme is discussed. The enzyme basic reaction mechanisms and actions are considered. The studies on enzyme physicochemical, kinetic, and catalytic research are presented. PMID:24479338

  11. Structural basis of nucleoside and nucleoside drug selectivity by concentrative nucleoside transporters

    PubMed Central

    Johnson, Zachary Lee; Lee, Jun-Ho; Lee, Kiyoun; Lee, Minhee; Kwon, Do-Yeon; Hong, Jiyong; Lee, Seok-Yong

    2014-01-01

    Concentrative nucleoside transporters (CNTs) are responsible for cellular entry of nucleosides, which serve as precursors to nucleic acids and act as signaling molecules. CNTs also play a crucial role in the uptake of nucleoside-derived drugs, including anticancer and antiviral agents. Understanding how CNTs recognize and import their substrates could not only lead to a better understanding of nucleoside-related biological processes but also the design of nucleoside-derived drugs that can better reach their targets. Here, we present a combination of X-ray crystallographic and equilibrium-binding studies probing the molecular origins of nucleoside and nucleoside drug selectivity of a CNT from Vibrio cholerae. We then used this information in chemically modifying an anticancer drug so that it is better transported by and selective for a single human CNT subtype. This work provides proof of principle for utilizing transporter structural and functional information for the design of compounds that enter cells more efficiently and selectively. DOI: http://dx.doi.org/10.7554/eLife.03604.001 PMID:25082345

  12. Comparison of the Cytotoxicity of the Nitroaromatic Drug Flutamide to Its Cyano Analogue in the Hepatocyte Cell Line TAMH: Evidence for Complex I Inhibition and Mitochondrial Dysfunction Using Toxicogenomic Screening

    PubMed Central

    Coe, Kevin J.; Jia, Yankai; Ho, Han Kiat; Rademacher, Peter; Bammler, Theo K.; Beyer, Richard P.; Farin, Frederico M.; Woodke, Libby; Plymate, Stephen R.; Fausto, Nelson; Nelson, Sidney D.

    2009-01-01

    Flutamide (FLU) is an antiandrogen primarily used in the treatment of metastatic prostate cancer. It is an idiosyncratic hepatotoxicant that sometimes results in severe liver toxicity. FLU possesses a nitroaromatic group, which may be a contributor to its mechanism of toxicity. A nitro to cyano analogue of FLU (CYA) was synthesized and used to test this hypothesis in the TGFα-transfected mouse hepatocyte cell line (TAMH). MTT cell viability assays and confocal microscopy showed that hepatocytes are more sensitive to cytotoxicity caused by FLU than CYA (LD50 75 vs 150 μM, respectively). Despite the structural modification, the antiandrogen activity of CYA is comparable to that of FLU. Comparisons of transcriptomic changes caused by FLU with those caused by a panel of known cytotoxicants [acetaminophen, tetrafluoroethylcysteine, diquat, and rotenone (ROT)] indicated that FLU results in a temporal gene expression pattern similar to ROT, a known inhibitor of complex I of the electron transport chain. A subsequent microarray analysis comparing FLU to CYA and ROT revealed many similarities among these three compounds; however, FLU and ROT result in more substantial changes than CYA in the expression of genes associated with oxidative phosphorylation, fatty acid β-oxidation, antioxidant defense, and cell death pathways. Electron microscopy confirmed that FLU leads to mitochondrial toxicity that has some similarities to the mitochondrial effects of ROT, but the morphologic changes caused by FLU were greater in scope with both intra- and intercellular manifestations. Biochemical studies confirmed that both ROT and FLU deplete cellular ATP levels and inhibit complex I of the electron transport chain to a greater extent than CYA. Thus, as compared to CYA, the nitroaromatic group of FLU enhances cytotoxicity to hepatocytes, likely through mechanisms involving mitochondrial dysfunction and ATP depletion that include complex I inhibition. PMID:17702527

  13. Nucleoside transporters in the disposition and targeting of nucleoside analogs in the kidney.

    PubMed

    Mangravite, Lara M; Badagnani, Ilaria; Giacomini, Kathleen M

    2003-10-31

    Systemic disposition of nucleosides and nucleoside analogs is dependent on renal handling of these compounds. There are five known, functionally characterized nucleoside transporters with varying substrate specificities for nucleosides: concentrative nucleoside transporters (CNT1-CNT3; Solute Carrier (SLC) 28A1-28A3), which mediate the intracellular flux of nucleosides, and equilibrative nucleoside transporters (ENT1-ENT2; SLC29A1-SLC29A2), which mediate bi-directional facilitated diffusion of nucleosides. All five of these transporters are expressed in the kidney. Concentrative nucleoside transporters primarily localize to the apical membrane of renal epithelial cells while equilibrative nucleoside transporters primarily localize to the basolateral membrane. These transporters work in concert to mediate reabsorptive flux of naturally occurring nucleosides and nucleoside analogs. In addition, equilibrative transporters also participate in secretory flux of some nucleoside analogs. Nucleoside transporters also serve in the targeting of nucleoside analog therapies to renal tumors. This review examines the role that these transporters play in renal disposition of nucleosides and nucleoside analogs in both systemic and kidney-specific therapies. PMID:14612157

  14. Overcoming nucleoside analog chemoresistance of pancreatic cancer: A therapeutic challenge

    PubMed Central

    Hung, Sau Wai; Mody, Hardik R.; Govindarajan, Rajgopal

    2013-01-01

    Clinical refractoriness to nucleoside analogs (e.g., gemcitabine, capecitabine) is a major scientific problem and is one of the main reasons underlying the extremely poor prognostic state of pancreatic cancer. The drugs’ effects are suboptimal partly due to cellular mechanisms limiting their transport, activation, and overall efficacy. Nonetheless, novel therapeutic approaches are presently under study to circumvent nucleoside analog resistance in pancreatic cancer. With these new approaches come additional challenges to be addressed. This review describes the determinants of chemoresistance in the gemcitabine cytotoxicity pathways, provides an overview of investigational approaches for overcoming chemoresistance, and discusses new challenges presented. Understanding the future directions of the field may assist in the successful development of novel treatment strategies for enhancing chemotherapeutic efficacy in pancreatic cancer. PMID:22425961

  15. Novel nucleoside-based antimalarial compounds.

    PubMed

    Zheng, Zhaoyan; Tran, Huu-Anh; Manivannan, Srinivasan; Wen, Xianghui; Kaiser, Marcel; Brun, Reto; Snyder, Floyd F; Back, Thomas G

    2016-06-15

    The malaria-causing parasite Plasmodium falciparum employs a salvage pathway for the biosynthesis of nucleotides, in contrast to de novo biosynthesis that is utilized by the human host. A series of twenty-two 2-, 6- and 5'-modified adenosine ribonucleosides was synthesized, with the expectation that these compounds would generate toxic metabolites instead of active nucleotides by the pathogen, while remaining inert in host cells. Bioassays with P. falciparum (K1 strain) indicated IC50 values as low as 110nM and a selectivity index with respect to cytotoxicity toward an L6 rat myoblast cell line of >1000 for the most potent analogue. PMID:27156774

  16. Interferon-free strategies without a nucleoside/nucleotide analogue.

    PubMed

    Welzel, Tania Mara; Zeuzem, Stefan

    2014-02-01

    The identification of viral and host factors involved in hepatitis C virus (HCV) replication was a key prerequisite for the discovery and further exploration of antiviral drug targets. As of today, numerous direct-acting antiviral agents (DAAs), as well as host-targeting agents (HTAs), have been developed and entered clinical testing. The goal to omit pegylated interferon due to its unfavorable side-effect profile from novel HCV therapeutic approaches led to an expedited design and competitive conduct of DAA combination trials striving for easily applicable, all-oral HCV treatments. Approval of several interferon-free regimens is awaited in the near future (2014/2015). Results of different DAA combination trials (without nucleos(t)ide polymerase inhibitors) and trials involving HTAs are reviewed herein. PMID:24782258

  17. Cytotoxicity and antileukaemic activity of new duplexes linking 3-C-ethynylcytidine and 5-fluorodeoxyuridine.

    PubMed

    Novotny, L; Rauko, P; Schott, H

    2010-12-01

    The cytotoxic and antineoplastic potential of two new duplex drugs, ECyd-5-FdU and ECyd- lipid- 5-FdU, were compared with the activity of the parent single-nucleoside analogues, 3-C-ethynylcytidine (ECyd) and 5-fluorodeoxyuridine (5-FdU), either applied as monotherapy or simultaneously in equimolar concentrations simulating their ratio in a duplex drug. Murine leukaemia L1210 cells were used for comparative in vitro tests of the duplex and the single drugs. The tested substances were evaluated for their cytotoxicity, combinatory potential and revitalisation properties. Additionally, an in vivo model of leukaemia L1210-bearing mice of the DBA/2J strain was used for testing of acute toxicity and antileukaemic activity using various chemotherapeutic regimes. Based on the results of this study, the suitability of ECyd and 5-FdU for forming a duplex drug was discussed from the perspective of their expected synergistic anticancer activities. We found an improvement of chemotherapy outcomes of the new duplex drugs tested by comparing their in vitro cytotoxicity and an increase of the time of survival of experimental leukaemia-bearing mice in a statistically significant manner. PMID:21187467

  18. Broad-spectrum non-nucleoside inhibitors of human herpesviruses

    PubMed Central

    McClain, Lora; Zhi, Yun; Cheng, Hoyee; Ghosh, Ayantika; Piazza, Paolo; Yee, Michael B.; Kumar, Santosh; Milosevic, Jadranka; Bloom, David C.; Arav-Boger, Ravit; Kinchington, Paul R.; Yolken, Robert; Nimgaonkar, Vishwajit; D’Aiuto, Leonardo

    2015-01-01

    Herpesvirus infections cause considerable morbidity and mortality through lifelong recurrent cycles of lytic and latent infection in several tissues, including the human nervous system. Acyclovir (ACV) and its prodrug, the current antivirals of choice for herpes simplex virus (HSV) and, to some extent, varicella zoster virus (VZV) infections are nucleoside analogues that inhibit viral DNA replication. Rising viral resistance and the need for more effective second-line drugs have motivated searches for additional antiviral agents, particularly non-nucleoside based agents. We evaluated the antiviral activity of five compounds with predicted lysosomotropic activity using conventional and human induced pluripotent stem cell-derived neuronal (iPSC-neurons) cultures. Their potency and toxicity were compared with ACV and the lysosomotropic agents chloroquine and bafilomycin A1. Out of five compounds tested, micromolar concentrations of 30N12, 16F19, and 4F17 showed antiviral activity comparable to ACV (50μM) during lytic herpes simplex virus type 1 (HSV-1) infections, reduced viral DNA copy number, and reduced selected HSV-1 protein levels. These compounds also inhibited the reactivation of ‘quiescent’ HSV-1 infection established in iPSC-neurons, but did not inhibit viral entry into host cells. The same compounds had greater potency than ACV against lytic VZV infection; they also inhibited replication of human cytomegalovirus. The anti-herpetic effects of these non-nucleoside agents merit further evaluation in vivo. PMID:26079681

  19. Broad-spectrum non-nucleoside inhibitors of human herpesviruses.

    PubMed

    McClain, Lora; Zhi, Yun; Cheng, Hoyee; Ghosh, Ayantika; Piazza, Paolo; Yee, Michael B; Kumar, Santosh; Milosevic, Jadranka; Bloom, David C; Arav-Boger, Ravit; Kinchington, Paul R; Yolken, Robert; Nimgaonkar, Vishwajit; D'Aiuto, Leonardo

    2015-09-01

    Herpesvirus infections cause considerable morbidity and mortality through lifelong recurrent cycles of lytic and latent infection in several tissues, including the human nervous system. Acyclovir (ACV) and its prodrug, the current antivirals of choice for herpes simplex virus (HSV) and, to some extent, varicella zoster virus (VZV) infections are nucleoside analogues that inhibit viral DNA replication. Rising viral resistance and the need for more effective second-line drugs have motivated searches for additional antiviral agents, particularly non-nucleoside based agents. We evaluated the antiviral activity of five compounds with predicted lysosomotropic activity using conventional and human induced pluripotent stem cell-derived neuronal (iPSC-neurons) cultures. Their potency and toxicity were compared with ACV and the lysosomotropic agents chloroquine and bafilomycin A1. Out of five compounds tested, micromolar concentrations of 30N12, 16F19, and 4F17 showed antiviral activity comparable to ACV (50μM) during lytic herpes simplex virus type 1 (HSV-1) infections, reduced viral DNA copy number, and reduced selected HSV-1 protein levels. These compounds also inhibited the reactivation of 'quiescent' HSV-1 infection established in iPSC-neurons, but did not inhibit viral entry into host cells. The same compounds had greater potency than ACV against lytic VZV infection; they also inhibited replication of human cytomegalovirus. The anti-herpetic effects of these non-nucleoside agents merit further evaluation in vivo. PMID:26079681

  20. Nucleoside derivatives from the marine-derived fungus Aspergillus versicolor.

    PubMed

    Chen, Min; Fu, Xiu-Mei; Kong, Chui-Jian; Wang, Chang-Yun

    2014-01-01

    Four nucleoside derivatives (1-4) were isolated from the fungus Aspergillus versicolor derived from the gorgonian Dichotella gemmacea collected in the South China Sea. Their structures were elucidated by comprehensive spectroscopic method of NMR and MS analysis. All isolated metabolites were evaluated for their cytotoxicity, antibacterial activity and lethality towards brine shrimp Artemia salina. Compounds 1/2 exhibited selective antibacterial activity against Staphylococcus epidermidis with an MIC value of 12.5 μM. It should be noted that 1 and 2, whose structures were listed in SciFinder Scholar, had no associated reference. This is the first report about their isolation, structure elucidation and biological activities. PMID:24670197

  1. The concentrative nucleoside transporter family, SLC28.

    PubMed

    Gray, Jennifer H; Owen, Ryan P; Giacomini, Kathleen M

    2004-02-01

    The SLC28 family consists of three subtypes of sodium-dependent, concentrative nucleoside transporters, CNT1, CNT2, and CNT3 (SLC28A1, SLC28A2, and SLC28A3, respectively), that transport both naturally occurring nucleosides and synthetic nucleoside analogs used in the treatment of various diseases. These subtypes differ in their substrate specificities: CNT1 is pyrimidine-nucleoside preferring, CNT2 is purine-nucleoside preferring, and CNT3 transports both pyrimidine and purine nucleosides. Recent studies have identified key amino acid residues that are determinants of pyrimidine and purine specificity of CNT1 and CNT2. The tissue distributions of the CNTs vary: CNT1 is localized primarily in epithelia, whereas CNT2 and CNT3 have more generalized distributions. Nucleoside transporters in the SLC28 and SLC29 families play critical roles in nucleoside salvage pathways where they mediate the first step of nucleotide biosynthesis. In addition, these transporters work in concert to terminate adenosine signaling. SLC28 family members are crucial determinants of response to a variety of anticancer and antiviral nucleoside analogs, as they modulate the entry of these analogs into target tissues. Further, this family is involved in the absorption and disposition of many nucleoside analogs. Several CNT single nucleoside polymorphisms (SNPs) have been identified, but have yet to be characterized. PMID:12856181

  2. Attenuation of nucleoside and anti-cancer nucleoside analog drug uptake in prostate cancer cells by Cimicifuga racemosa extract BNO-1055.

    PubMed

    Dueregger, Andrea; Guggenberger, Fabian; Barthelmes, Jan; Stecher, Günther; Schuh, Markus; Intelmann, Daniel; Abel, Gudrun; Haunschild, Jutta; Klocker, Helmut; Ramoner, Reinhold; Sampson, Natalie

    2013-11-15

    This study aimed to investigate the mechanisms underlying the anti-proliferative effects of the ethanolic Cimicifuga racemosa extract BNO-1055 on prostate cells and evaluate its therapeutic potential. BNO-1055 dose-dependently attenuated cellular uptake and incorporation of thymidine and BrdU and significantly inhibited cell growth after long-time exposure. Similar results were obtained using saponin-enriched sub-fractions of BNO-1055. These inhibitory effects of BNO-1055 could be mimicked using pharmacological inhibitors and isoform-specific siRNAs targeting the equilibrative nucleoside transporters ENT1 and ENT2. Moreover, BNO-1055 attenuated the uptake of clinically relevant nucleoside analogs, e.g. the anti-cancer drugs gemcitabine and fludarabine. Consistent with inhibition of the salvage nucleoside uptake pathway BNO-1055 potentiated the cytotoxicity of the de novo nucleotide synthesis inhibitor 5-FU without significantly altering its uptake. Collectively, these data show for the first time that the anti-proliferative effects of BNO-1055 result from hindered nucleoside uptake due to impaired ENT activity and demonstrate the potential therapeutic use of BNO-1055 for modulation of nucleoside transport. PMID:23972793

  3. Stable expression of a recombinant sodium-dependent, pyrimidine-selective nucleoside transporter (CNT1) in a transport-deficient mouse leukemia cell line.

    PubMed

    Crawford, C R; Cass, C E; Young, J D; Belt, J A

    1998-01-01

    Previous studies of nucleoside transport in mammalian cells have identified two types of activities: the equilibrative nucleoside transporters and concentrative, Na+-nucleoside cotransporters. Characterization of the concentrative nucleoside transporters has been hampered by the presence in most cells and tissues of multiple transporters with overlapping permeant specificities. With the recent cloning of cDNAs encoding rat and human members of the concentrative nucleoside transporter (CNT) family, it is now possible to study the concentrative transporters in isolation by use of functional expression systems. We report here the isolation of a nucleoside transport-deficient subline of L1210 mouse leukemia (L1210/DNC3) that is a suitable recipient for stable expression of cloned nucleoside transporter cDNAs. We have used L1210/DNC3 as the recipient in gene transfer studies to develop a stable cell line (L1210/DU5) that produces the recombinant concentrative nucleoside transporter with selectivity for pyrimidine nucleosides (CNT1) that was initially identified in rat intestine (Q.Q. Huang, S.Y. Yao, M.W. Ritzel, A.R.P. Paterson, C.E. Cass, and J.D. Young. 1994. J. Biol. Chem. 269: 17,757-17,760). L1210/DU5 was used to examine the permeant selectivity of recombinant rat CNT1 by comparing a series of nucleoside analogs with respect to (i) inhibition of inward fluxes of [3H]thymidine, (ii) initial rates of transport of 3H-analog, and (iii) cytotoxicity to L1210/DU5 versus the parental transport-deficient cell line. By all three criteria, recombinant CNT1 transported 5-fluoro-2'-deoxyuridine and 5-fluorouridine well and cytosine arabinoside poorly. Although some purine nucleosides (2'-deoxyadenosinedeoxyadeno-2'-deoxyadenosine, 7-deazaadenosine) were potent inhibitors of CNT1, they were poor permeants when uptake was measured directly by analysis of isotopic fluxes or indirectly by comparison of cytotoxicity ratios. We conclude that comparison of analog cytotoxicity to L

  4. Design and synthesis of novel 5-substituted acyclic pyrimidine nucleosides as potent and selective inhibitors of hepatitis B virus.

    PubMed

    Kumar, Rakesh; Nath, Mahendra; Tyrrell, D Lorne J

    2002-05-01

    A novel class of 5-substituted acyclic pyrimidine nucleosides, 1-[(2-hydroxyethoxy)methyl]-5-(1-azidovinyl)uracil (9a), 1-[(2-hydroxy-1-(hydroxymethyl)ethoxy)methyl]-5-(1-azidovinyl)uracil (9b), and 1-[4-hydroxy-3-(hydroxymethyl)-1-butyl]-5-(1-azidovinyl)uracil (9c), were synthesized by regiospecific addition of bromine azide to the 5-vinyl substituent of the respective 5-vinyluracils (2a-c) followed by treatment of the obtained 5-(1-azido-2-bromoethyl) compounds (3a-c) with t-BuOK, to affect the base-catalyzed elimination of HBr. Thermal decomposition of 9b and 9c at 110 degrees C in dioxane yielded corresponding 5-[2-(1-azirinyl)]uracil analogues (10b,c). The 5-(1-azidovinyl)uracil derivatives 9a-c were found to exhibit potent and selective in vitro anti-HBV activity against duck hepatitis B virus (DHBV) infected primary duck hepatocytes at low concentrations (EC(50) = 0.01-0.1 microg/mL range). The most active anti-DHBV agent (9c), possessing a [4-hydroxy-3-(hydroxymethyl)-1-butyl] substituent at N-1, exhibited an activity (EC(50) of 0.01-0.05 microg/mL) comparable to that of reference compound (-)-beta-L-2',3'-dideoxy-3'-thiacytidine (3-TC) (EC(50) = 0.01-0.05 microg/mL). In contrast, related 5-[2-(1-azirinyl)]uracil analogues (10b,c) were devoid of anti-DHBV activity, indicating that an acyclic side chain at C-5 position of the pyrimidine ring is essential for anti-HBV activity. The pyrimidine nucleosides (9a-c, 10b,c) exhibited no cytotoxic activity against a panel of 60 human cancer cell lines. All of the compounds investigated did not show any detectable toxicity to several stationary and proliferating host cell lines or to mitogen stimulated proliferating human T lymphocytes, up to the highest concentration tested. PMID:11985471

  5. Nucleoside transporter subtype expression: effects on potency of adenosine kinase inhibitors

    PubMed Central

    Sinclair, C J D; Powell, A E; Xiong, W; LaRivière, C G; Baldwin, S A; Cass, C E; Young, J D; Parkinson, F E

    2001-01-01

    Adenosine kinase (AK) inhibitors can enhance adenosine levels and potentiate adenosine receptor activation. As the AK inhibitors 5′ iodotubercidin (ITU) and 5-amino-5′-deoxyadenosine (NH2dAdo) are nucleoside analogues, we hypothesized that nucleoside transporter subtype expression can affect the potency of these inhibitors in intact cells.Three nucleoside transporter subtypes that mediate adenosine permeation of rat cells have been characterized and cloned: equilibrative transporters rENT1 and rENT2 and concentrative transporter rCNT2. We stably transfected rat C6 glioma cells, which express rENT2 nucleoside transporters, with rENT1 (rENT1-C6 cells) or rCNT2 (rCNT2-C6 cells) nucleoside transporters.We tested the effects of ITU and NH2dAdo on [3H]-adenosine uptake and conversion to [3H]-adenine nucleotides in the three cell types. NH2dAdo did not show any cell type selectivity. In contrast, ITU showed significant inhibition of [3H]-adenosine uptake and [3H]-adenine nucleotide formation at concentrations ⩽100 nM in rENT1-C6 cells, while concentrations ⩾3 μM were required for C6 or rCNT2-C6 cells.Nitrobenzylthioinosine (NBMPR; 100 nM), a selective inhibitor of rENT1, abolished the effects of nanomolar concentrations of ITU in rENT1-C6 cells.This study demonstrates that the effects of ITU, but not NH2dAdo, in whole cell assays are dependent upon nucleoside transporter subtype expression. Thus, cellular and tissue differences in expression of nucleoside transporter subtypes may affect the pharmacological actions of some AK inhibitors. PMID:11682452

  6. Synthesis of novel fluorocarbocyclic nucleosides and nucleotides as potential inhibitors of human immunodeficiency virus

    SciTech Connect

    Hilpert, H.

    1989-01-01

    3[prime]-Azido-3[prime]-deoxythymidine (AZT) and 2[prime], 3[prime]-dideoxycytidine (DDC) are potent in vivo inhibitors of human immunodeficiency virus. Due to their short half-life in the body and undesired side-effects compounds with improved bioavailability were designed. A feature of these analogues was the replacement of the heterocyclic oxygen atom by an isosteric CHF-group thus stabilizing the labile glycosidic bond against metabolic breakdown. A versatile and short synthesis, starting from ketone, serves to construct the highly functionalized and protected key intermediates. These ([alpha]- and [beta]-fluoro epimeric) intermediates were elaborated to eight fluorocarbocyclic nucleoside analogues linked with a thymine base, an adenine base, and a guanine base. An attempt was made to prepare analogues of the potent HIV inhibitor carbovir c. The unexpected oxidation of the double bond of compound d, instead of the desired Baeyer-Villiger ring-expansion, meant that the synthetic scheme was redundant. A second total synthesis involves the preparation of the three fluorocarbocyclic phosphonates. These analogues possess additionally a P-C linkage which should markedly enhance the stability of the side chain. To perform enzyme inhibition tests, three analogues were chemically activated to the biologically active triphosphates. Inhibition tests on HIV associated reverse transcriptase confirmed the high activity of one of the AZT triphosphates. The fluorocarbocyclic counterpart was two orders of magnitude less active. A fluorocarbocyclic phosphonate was twice as active as the AZT triphosphate. Neither the eight nucleoside analogues nor the three phosphonates displayed significant activity against HIV infected cells. Crystallographic data of two fluorocarbocyclic nucleosides, two potent HIV inhibitors, and some 20 examples of 2[prime]-deoxyribonucleosides have been compared.

  7. Marine Nucleosides: Structure, Bioactivity, Synthesis and Biosynthesis

    PubMed Central

    Huang, Ri-Ming; Chen, Yin-Ning; Zeng, Ziyu; Gao, Cheng-Hai; Su, Xiangdong; Peng, Yan

    2014-01-01

    Nucleosides are glycosylamines that structurally form part of nucleotide molecules, the building block of DNA and RNA. Both nucleosides and nucleotides are vital components of all living cells and involved in several key biological processes. Some of these nucleosides have been obtained from a variety of marine resources. Because of the biological importance of these compounds, this review covers 68 marine originated nucleosides and their synthetic analogs published up to June 2014. The review will focus on the structures, bioactivities, synthesis and biosynthetic processes of these compounds. PMID:25474189

  8. Base-Modified Nucleosides: Etheno Derivatives

    PubMed Central

    Jahnz-Wechmann, Zofia; Framski, Grzegorz R.; Januszczyk, Piotr A.; Boryski, Jerzy

    2016-01-01

    This review presents synthesis and chemistry of nucleoside analogs, possessing an additional fused, heterocyclic ring of the “etheno” type, such as 1,N6-ethenoadenosine, 1,N4-ethenocytidine, 1,N2-ethenoguanosine, and other related derivatives. Formation of ethenonucleosides, in the presence of α-halocarbonyl reagents and their mechanism, stability, and degradation, reactions of substitution and transglycosylation, as well as their application in the nucleoside synthesis, have been described. Some of the discussed compounds may be applied as chemotherapeutic agents in antiviral and anticancer treatment, acting as pro-nucleosides of already known, biologically active nucleoside analogs. PMID:27200341

  9. L-Aspartic and l-glutamic acid ester-based ProTides of anticancer nucleosides: Synthesis and antitumoral evaluation.

    PubMed

    Gao, Ling-Jie; De Jonghe, Steven; Daelemans, Dirk; Herdewijn, Piet

    2016-05-01

    A series of novel aryloxyphosphoramidate nucleoside prodrugs based on l-aspartic acid and l-glutamic acid as amino acid motif has been synthesized and evaluated for antitumoral activity. Depending on the cancer cell line studied and on the nature of the parent nucleoside compound (gemcitabine, 5-iodo-2'-deoxy-uridine, floxuridine or brivudin), the corresponding ProTides are endowed with an improved or decreased cytotoxic activity. PMID:27032331

  10. Purine nucleoside phosphorylase as a cytosolic arsenate reductase.

    PubMed

    Gregus, Zoltán; Németi, Balázs

    2002-11-01

    The findings of the accompanying paper (Németi and Gregus, Toxicol: Sci. 70, 4-12) indicate that the arsenate (AsV) reductase activity of rat liver cytosol is due to an SH enzyme that uses phosphate (or its analogue, arsenate, AsV) and a purine nucleoside (guanosine or inosine) as substrates. Purine nucleoside phosphorylase (PNP) is such an enzyme. It catalyzes the phosphorolytic cleavage of 6-oxopurine nucleosides according to the following scheme: guanosine (or inosine) + phosphate <--> guanine (or hypoxanthine) + ribose-1-phosphate. Therefore, we have tested the hypothesis that PNP is responsible for the thiol- and purine nucleoside-dependent reduction of AsV to AsIII by rat liver cytosol. AsIII formed from AsV was quantified by HPLC-hydride generation-atomic fluorescence spectrometry analysis of the deproteinized incubates. The following findings support the conclusion that PNP reduces AsV to AsIII, using AsV instead of phosphate in the reaction above: (1) Specific PNP inhibitors (CI-1000, BCX-1777) at a concentration of 1 microM completely inhibited cytosolic AsV reductase activity. (2) During anion-exchange chromatography of cytosolic proteins, PNP activity perfectly coeluted with the AsV reductase activity, suggesting that both activities belong to the same protein. (3) PNP purified from calf spleen catalyzed reduction of AsV to AsIII in the presence of dithiothreitol (DTT) and a 6-oxopurine nucleoside (guanosine or inosine). (4) AsV reductase activity of purified PNP, like the cytosolic AsV reductase activity, was inhibited by phosphate (a substrate of PNP alternative to AsV), guanine and hypoxanthine (products of PNP favoring the reverse reaction), mercurial thiol reagents (nonspecific inhibitors of PNP), as well as CI-1000 and BCX-1777 (specific PNP inhibitors). Thus, PNP appears to be responsible for the AsV reductase activity of rat liver cytosol in the presence of DTT. Further research should clarify the mechanism and the in vivo significance of PNP

  11. Pyrrolobenzoxazepinone derivatives as non-nucleoside HIV-1 RT inhibitors: further structure-activity relationship studies and identification of more potent broad-spectrum HIV-1 RT inhibitors with antiviral activity.

    PubMed

    Campiani, G; Morelli, E; Fabbrini, M; Nacci, V; Greco, G; Novellino, E; Ramunno, A; Maga, G; Spadari, S; Caliendo, G; Bergamini, A; Faggioli, E; Uccella, I; Bolacchi, F; Marini, S; Coletta, M; Nacca, A; Caccia, S

    1999-10-21

    Pyrrolobenzoxazepinone (PBO) derivatives represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTs) whose prototype is (+/-)-6-ethyl-6-phenylpyrrolo[2,1-d][1,5]benzoxazepin-7(6H)- one (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis and biological evaluation of novel derivatives and analogues of 6 featuring a meta-substituted phenyl or a 2-thienyl ring at C-6 and a pyridine system in place of the fused-benzene ring to yield pyrrolopyridooxazepinones (PPOs). Compared with the lead 6 and nevirapine, several of the synthesized compounds (PBOs 13a-d and PPOs 13i-k) displayed higher inhibitory activity against wild-type RT and clinically relevant mutant RTs containing the single amino acid substitutions L100I, K103N, V106A, Y181I, and Y188L. The most potent inhibitors were further evaluated for in vitro antiviral activity on lymphocytes and monocyte-macrophages, for cytotoxicity on a panel of cell lines, and for potential synergistic antiviral activity with AZT. Pharmacokinetic studies performed on 13b, 13c, and 13i showed that these compounds achieve high concentrations in the brain. The results of the biological and pharmacokinetic experiments suggest a potential clinical utility of analogues such as 13b-d, 13i, and 13j, in combination with nucleoside RT inhibitors, against strains of HIV-1 bearing those mutations that confer resistance to known NNRTI. PMID:10543890

  12. Alpha-carboxy nucleoside phosphonates as universal nucleoside triphosphate mimics

    PubMed Central

    Balzarini, Jan; Das, Kalyan; Bernatchez, Jean A.; Martinez, Sergio E.; Ngure, Marianne; Keane, Sarah; Ford, Alan; Maguire, Nuala; Mullins, Niki; John, Jubi; Kim, Youngju; Dehaen, Wim; Vande Voorde, Johan; Liekens, Sandra; Naesens, Lieve; Götte, Matthias; Maguire, Anita R.; Arnold, Eddy

    2015-01-01

    Polymerases have a structurally highly conserved negatively charged amino acid motif that is strictly required for Mg2+ cation-dependent catalytic incorporation of (d)NTP nucleotides into nucleic acids. Based on these characteristics, a nucleoside monophosphonate scaffold, α-carboxy nucleoside phosphonate (α-CNP), was designed that is recognized by a variety of polymerases. Kinetic, biochemical, and crystallographic studies with HIV-1 reverse transcriptase revealed that α-CNPs mimic the dNTP binding through a carboxylate oxygen, two phosphonate oxygens, and base-pairing with the template. In particular, the carboxyl oxygen of the α-CNP acts as the potential equivalent of the α-phosphate oxygen of dNTPs and two oxygens of the phosphonate group of the α-CNP chelate Mg2+, mimicking the chelation by the β- and γ-phosphate oxygens of dNTPs. α-CNPs (i) do not require metabolic activation (phosphorylation), (ii) bind directly to the substrate-binding site, (iii) chelate one of the two active site Mg2+ ions, and (iv) reversibly inhibit the polymerase catalytic activity without being incorporated into nucleic acids. In addition, α-CNPs were also found to selectively interact with regulatory (i.e., allosteric) Mg2+-dNTP-binding sites of nucleos(t)ide-metabolizing enzymes susceptible to metabolic regulation. α-CNPs represent an entirely novel and broad technological platform for the development of specific substrate active- or regulatory-site inhibitors with therapeutic potential. PMID:25733891

  13. Cytidine is a novel substrate for wild-type concentrative nucleoside transporter 2.

    PubMed

    Nagai, Katsuhito; Nagasawa, Kazuki; Koma, Mineto; Hotta, Ayumi; Fujimoto, Sadaki

    2006-08-25

    Nucleoside transporter (NT) plays key roles in the physiology of nucleosides and the pharmacology of its analogues in mammals. We previously cloned Na+/nucleoside cotransporter CNT2 from mouse M5076 ovarian sarcoma cells, the peptide encoded by it differing from that by the previously reported mouse CNT2 in five substitutions, and observed that the transporter can take up cytidine, like CNT1 and CNT3. In the present study, we examined which of the two aforementioned CNT2 is the normal one, and whether or not cytidine is transported via the previously reported CNT2. The peptide encoded by CNT2 derived from mouse intestine, liver, spleen, and ovary was identical to that previously reported. The uptake of [3H]cytidine, but not [3H]thymidine, by Cos-7 cells transfected with CNT2 cDNA obtained from mouse intestine was much greater than that by mock cells, as in the case of [3H]uridine, a typical substrate of NT. [3H]Cytidine and [3H]uridine were taken up via CNT2, in temperature-, extracellular Na+-, and substrate concentration-dependent manners. The uptake of [3H]cytidine and [3H]uridine mediated by CNT2 was significantly inhibited by the variety of nucleosides used in this study, except for thymidine, and inhibition of the [3H]uridine uptake by cytidine was competitive. The [3H]uridine uptake via CNT2 was significantly decreased by the addition of cytarabin or gemcitabine, antimetabolites of cytidine analogue. These results indicated that the previously reported mouse CNT2 is the wild-type one, and cytidine is transported mediated by the same recognition site on the CNT2 with uridine, and furthermore, cytidine analogues may be substrates for the transporter. PMID:16828706

  14. Characterization of intestinal absorption of mizoribine mediated by concentrative nucleoside transporters in rats.

    PubMed

    Mori, Nobuhiro; Yokooji, Tomoharu; Kamio, Yoshihiro; Murakami, Teruo

    2008-05-31

    Mizoribine, an imidazole nucleoside, is an inhibitor of purine synthesis and has been used as an orally available immunosuppressive agent in human renal transplantation. In the present study, the intestinal absorption of mizoribine was characterized by examining the contribution of concentrative nucleoside transporters (CNT1, CNT2) in rats. When mizoribine was administered orally in conscious rats, the bioavailability of mizoribine estimated by urinary excretion percentage of unchanged mizoribine was a dose dependent: 53.1+/-6.0% at 5 mg/kg and 24.0+/-5.1% at 20 mg/kg. In in-situ loop studies, the disappearance rate, or absorption rate, of mizoribine from the intestinal lumen was comparable between 1 and 5 mg/kg, but significantly lower at 25 mg/kg. Coadministration of adenosine (a substrate of both CNT1 and CNT2), thymidine (a CNT1 substrate) and inosine (a CNT2 substrate) significantly suppressed the intestinal mizoribine absorption, depending on the nucleoside concentrations coadministered. Gemcitabine (a pyrimidine nucleoside analogue, a CNT1 substrate) and ribavirin (a purine nucleoside analog, a CNT2 substrate) also significantly suppressed the mizoribine intestinal absorption. Bile salts such as sodium cholate and sodium glycocholate (10 mM) also significantly suppressed the intestinal mizoribine absorption, but not ribavirin absorption. Mizoribine is an amphoteric compound, however, the suppression of intestinal absorption by bile salts was not ascribed to the electrostatic interaction or micellar formation between mizoribine and bile salts. In conclusion, the intestinal absorption of mizoribine is mediated by CNT1 and CNT2, and nucleoside-derived drugs such as gemcitabine and ribavirin can suppress the intestinal absorption of mizoribine. Bile salts such as sodium glycocholate were also found to cause interaction with mizoribine. PMID:18371949

  15. Nonenantioselectivity Property of Human Deoxycytidine Kinase Explained by Structures of the Enzyme in Complex with [subscript L]- and [subscript D]-Nucleosides

    SciTech Connect

    Sabini, Elisabetta; Hazra, Saugata; Konrad, Manfred; Lavie, Arnon

    2008-07-31

    Biological molecules are predominantly enantioselective. Yet currently two nucleoside analogue prodrugs (3TC and FTC) with opposite chirality compared to physiological nucleosides are clinically approved for the treatment of HIV infections. These prodrugs require conversion to their triphosphorylated forms to achieve pharmacological activity. The first step in the activation of these agents is catalyzed by human deoxycytidine kinase (dCK). This enzyme possesses the ability to phosphorylate nucleosides of the unnatural L-chirality. To understand the molecular basis for the nonenantioselectivity of dCK, we solved the crystal structures of the enzyme in complex with the L-enantiomer and of its physiological substrate deoxycytidine and with the L-nucleoside analogue FTC. These were compared to a structure solved with D-dC. Our results highlight structural adjustments imposed on the L-nucleosides and properties of the enzyme endowing it with the ability to phosphorylate substrates with nonphysiological chirality. This work reveals the molecular basis for the activation of L-nucleosides by dCK.

  16. Synthesis of Conformationally North-Locked Pyrimidine Nucleosides Built on an Oxa-bicyclo[3.1.0]hexane Scaffold

    PubMed Central

    Ludek, Olaf R.; Marquez, Victor E.

    2011-01-01

    Beginning with a known 3-oxabicyclo[3.1.0]hexane scaffold (I), the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template (II) that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel approach that required the isocyanate II (B = NCO) with a hydroxyl-protected scaffold as a pivotal intermediate that was obtained in eleven steps from a known dihydrofuran precursor. The completion of the nucleobases was successfully achieved by quenching the isocyanate with the lithium salts of the corresponding acrylic amides that led to the uracil and thymidine precursors in a single step. Ring closure of these intermediates led to the target, locked nucleosides. The anti-HIV activity of 29 (uridine analogue), 31 (thymidine analogue), and 34 (cytidine analogue) was explored in human osteosarcoma (HOS) cells or modified HOS cells (HOS-313) expressing the herpes simplex virus 1 thymidine kinase (HSV-1 TK). Only the cytidine analogue showed moderate activity in HOS-313 cells, which means that the compounds are not good substrates for the cellular kinases. PMID:22026578

  17. Synthesis and Anti-HCV Activity of 4-Methoxy-7H-Pyrrolo[2,3-d] Pyrimidine Carbocyclic Nucleosides.

    PubMed

    Thiyagarajan, Anandarajan; Toyama, Masaaki; Baba, Masanori; Sharon, Ashoke; Bal, Chandralata

    2016-06-01

    The present study includes the exploration of new possible nucleoside mimetics based on 4-methoxy-7H-pyrrolo[2,3-d]pyrimidine carbocyclic nucleosides (4a-g), which were synthesized by 10-15 synthetic steps and characterized adequately. We report the anti-HCV activities and cytotoxicities of 4a-g. Compound 4a was analyzed by single crystal X-ray diffraction which showed some puckering in the cyclopentene ring with a 2'-endo conformation and anti-base disposition (χ = -125.7°). PMID:27152477

  18. Pseudobond parameters for QM/MM studies involving nucleosides, nucleotides, and their analogs

    NASA Astrophysics Data System (ADS)

    Chaudret, Robin; Parks, Jerry M.; Yang, Weitao

    2013-01-01

    In biological systems involving nucleosides, nucleotides, or their respective analogs, the ribose sugar moiety is the most common reaction site, for example, during DNA replication and repair. However, nucleic bases, which comprise a sizable portion of nucleotide molecules, are usually unreactive during such processes. In quantum mechanical/molecular simulations of nucleic acid reactivity, it may therefore be advantageous to describe specific ribosyl or ribosyl phosphate groups quantum mechanically and their respective nucleic bases with a molecular mechanics potential function. Here, we have extended the pseudobond approach to enable quantum mechanical/molecular mechanical simulations involving nucleotides, nucleosides, and their analogs in which the interface between the two subsystems is located between the sugar and the base, namely, the C(sp3)-N(sp2) bond. The pseudobond parameters were optimized on a training set of 10 molecules representing several nucleotide and nucleoside bases and analogs, and they were then tested on a larger test set of 20 diverse molecules. Particular emphasis was placed on providing accurate geometries and electrostatic properties, including electrostatic potential, natural bond orbital (NBO) and atoms in molecules (AIM) charges and AIM first moments. We also tested the optimized parameters on five nucleotide and nucleoside analogues of pharmaceutical relevance and a small polypeptide (triglycine). Accuracy was maintained for these systems, which highlights the generality and transferability of the pseudobond approach.

  19. Synthesis and Cytoxicity of Sempervirine and Analogues.

    PubMed

    Pan, Xiaohong; Yang, Chunying; Cleveland, John L; Bannister, Thomas D

    2016-03-01

    Sempervirine and analogues were synthesized using a route featuring Sonogashira and Larock Pd-catalyzed reactions. Structure-activity relationships were investigated using three human cancer cell lines. 10-Fluorosempervirine is the most potently cytotoxic member of the family yet described. PMID:26828413

  20. Carboranyl Nucleosides & Oligonucleotides for Neutron Capture Therapy Final Report

    SciTech Connect

    Schinazi, Raymond F.

    2004-12-01

    This proposal enabled us to synthesize and develop boron-rich nucleosides and oligonucleotide analogues for boron neutron capture therapy (BNCT) and the treatment of various malignancies. First, we determined the relationship between structure, cellular accumulation and tissue distribution of 5-o-carboranyl-2'-deoxyuridine (D-CDU) and its derivatives D-ribo-CU and 5-o-carboranyluracil (CU), to potentially target brain and other solid tumors for neutron capture therapy. Synthesized carborane containing nucleoside derivatives of CDU, D- and L-enantiomers of CDU, D-ribo-CU and CU were used. We measured tissue disposition in xenografted mice bearing 9479 human prostate tumors xenografts and in rats bearing 9L gliosarcoma isografts in their flanks and intracranially. The accumulation of D-CDU, 1-({beta}-L-arabinosyl)-5-o-carboranyluracil, D-ribo-CU, and CU were also studied in LnCap human prostate tumor cells and their retention was measured in male nude mice bearing LnCap and 9479 human prostate tumor xenografts. D-CDU, D-ribo-CU and CU levels were measured after administration in mice bearing 9479 human prostate tumors in their flanks. D-CDU achieved high cellular concentrations in LnCap cells and up to 2.5% of the total cellular compound was recovered in the 5'-monophosphorylated form. D-CDU cellular concentrations were similar in LnCap and 9479 tumor xenografts. Studies in tumor bearing animals indicated that increasing the number of hydroxyl moieties in the sugar constituent of the carboranyl nucleosides lead to increased rate and extent of renal elimination, a decrease in serum half-lives and an increased tissue specificity. Tumor/brain ratios were greatest for CDU and D-ribo-CU, while tumor/prostate ratios were greatest with CU. CDU and D-ribo-CU have potential for BNCT of brain malignancies, while CU may be further developed for prostate cancer. A method was developed for the solid phase synthesis of oligonucleotides containing (ocarboran-1-yl

  1. Conformationally rigid nucleoside probes help understand the role of sugar pucker and nucleobase orientation in the thrombin-binding aptamer

    PubMed Central

    Saneyoshi, Hisao; Mazzini, Stefania; Aviñó, Anna; Portella, Guillem; González, Carlos; Orozco, Modesto; Marquez, Víctor E.; Eritja, Ramon

    2009-01-01

    Modified thrombin-binding aptamers carrying 2′-deoxyguanine (dG) residues with locked North- or South-bicyclo[3.1.0]hexane pseudosugars were synthesized. Individual 2′-deoxyguanosines at positions dG5, dG10, dG14 and dG15 of the aptamer were replaced by these analogues where the North/anti and South/syn conformational states were confined. It was found that the global structure of the DNA aptamer was, for the most part, very accommodating. The substitution at positions 5, 10 and 14 with a locked South/syn-dG nucleoside produced aptamers with the same stability and global structure as the innate, unmodified one. Replacing position 15 with the same South/syn-dG nucleoside induced a strong destabilization of the aptamer, while the antipodal North/anti-dG nucleoside was less destabilizing. Remarkably, the insertion of a North/anti-dG nucleoside at position 14, where both pseudosugar conformation and glycosyl torsion angle are opposite with respect to the native structure, led to the complete disruption of the G-tetraplex structure as detected by NMR and confirmed by extensive molecular dynamics simulations. We conclude that conformationally locked bicyclo[3.1.0]hexane nucleosides appear to be excellent tools for studying the role of key conformational parameters that are critical for the formation of a stable, antiparallel G-tetrad DNA structures. PMID:19620215

  2. Structural modifications of nucleosides in ionic liquids

    PubMed Central

    Kumar, Vineet; Parmar, Virinder S.; Malhotra, Sanjay V.

    2011-01-01

    Nucleoside chemistry represents an important research area for drug discovery, as many nucleoside analogs are prominent drugs and have been widely applied for cancer and viral chemotherapy. However, the synthesis of modified nucleosides presents a major challenge, which is further aggravated by poor solubility of these compounds in common organic solvents. Most of the currently available methods for nucleoside modification employ toxic high boiling solvents; require long reaction time and tedious workup methods. As such, there is constant effort to develop process chemistry in alternative medium to limit the use of organic solvents that are hazardous to the environment and can be deleterious to human health. One such approach is to use ionic liquids, which are ‘designer materials’ with unique and tunable physico-chemical properties. Studies have shown that methodologies using ionic liquids are highly efficient and convenient for the synthesis of nucleoside analogs, as demonstrated by the preparation of pharmaceutically important anti-viral drugs. This article summarizes recent efforts on nucleoside modification using ionic liquids. PMID:20178825

  3. A novel bis(pinacolato)diboron-mediated N-O bond deoxygenative route to C6 benzotriazolyl purine nucleoside derivatives.

    PubMed

    Basava, Vikram; Yang, Lijia; Pradhan, Padmanava; Lakshman, Mahesh K

    2016-08-01

    Reaction of amide bonds in t-butyldimethylsilyl-protected inosine, 2'-deoxyinosine, guanosine, 2'-deoxyguanosine, and 2-phenylinosine with commercially available peptide-coupling agents (benzotriazol-1H-yloxy)tris(dimethylaminophosphonium) hexafluorophosphate (BOP), (6-chloro-benzotriazol-1H-yloxy)trispyrrolidinophosphonium hexafluorophosphate (PyClocK), and (7-azabenzotriazol-1H-yloxy)trispyrrolidinophosphonium hexafluorophospate (PyAOP) gave the corresponding O(6)-(benzotriazol-1-yl) nucleoside analogues containing a C-O-N bond. Upon exposure to bis(pinacolato)diboron and base, the O(6)-(benzotriazol-1-yl) and O(6)-(6-chlorobenzotriazol-1-yl) purine nucleoside derivatives obtained from BOP and PyClocK, respectively, underwent N-O bond reduction and C-N bond formation, leading to the corresponding C6 benzotriazolyl purine nucleoside analogues. In contrast, the 7-azabenzotriazolyloxy purine nucleoside derivatives did not undergo efficient deoxygenation, but gave unsymmetrical nucleoside dimers instead. This is consistent with a prior report on the slow reduction of 1-hydroxy-1H-4-aza and 1-hydroxy-1H-7-azabenzotriazoles. Because of the limited number of commercial benzotriazole-based peptide coupling agents, and to show the applicability of the method when such coupling agents are unavailable, 1-hydroxy-1H-5,6-dichlorobenzotriazole was synthesized. Using this compound, silyl-protected inosine and 2'-deoxyinosine were converted to the O(6)-(5,6-dichlorobenzotriazol-1-yl) derivatives via in situ amide activation with PyBroP. The O(6)-(5,6-dichlorobenzotriazol-1-yl) purine nucleosides so obtained also underwent smooth reduction to afford the corresponding C6 5,6-dichlorobenzotriazolyl purine nucleoside derivatives. A total of 13 examples were studied with successful reactions occurring in 11 cases (the azabenzotriazole derivatives, mentioned above, being the only unreactive entities). To understand whether these reactions are intra or intermolecular processes, a

  4. Nucleoside transporters and liver cell growth.

    PubMed

    Pastor-Anglada, M; Felipe, A; Casado, F J; del Santo, B; Mata, J F; Valdés, R

    1998-01-01

    Liver parenchymal cells show a wide variety of plasma membrane transporters that are tightly regulated by endocrine and nutritional factors. This review summarizes work performed in our laboratory on these transport systems, particularly nucleoside transporters, which are up-regulated in physiological situations associated with liver cell growth. Rat hepatocytes show a Na+-dependent nucleoside transport activity that is stimulated by pancreatic hormones. Indeed, this biological activity appears to be the result of the co-expression of at least two isoforms of nucleoside carriers, CNT1 and CNT2 (also called SPNT). These two transporters are up-regulated during the early phase of liver growth after partial hepatectomy, although to different extents, suggesting differential regulation of the two isoforms. The recent generation of isoform-specific antibodies allowed us to demonstrate that carrier expression may also have complex post-transcriptional regulation on the basis of the lack of correspondence between mRNA and protein levels. The analysis of nucleoside transport systems in hepatoma cells and the comparison with those in hepatocytes has also provided evidence that the differentiation status of liver parenchymal cells may determine the pattern of nucleoside transporters expressed. PMID:10353710

  5. IODINE MONOCHLORIDE FACILITATED DEGLYCOSYLATION, ANOMERIZATION, AND ISOMERIZATION OF 3-SUBSTITUTED THYMIDINE ANALOGUES

    PubMed Central

    Khalil, Ahmed; Ishita, Keisuke; Ali, Tehane; Tiwari, Rohit; Riachy, Ramy; Toppino, Antonio; Hasabelnaby, Sherifa; Sayfullin, Naum; Oliver, Allen G.; Gallucci, Judith; Huang, Zhenguo; Tjarks, Werner

    2014-01-01

    The reaction of thymidine, 3-mono-, and 3,3′,5′-trialkylsubstitued thymidine analogues with iodine monochloride (ICl) was investigated. Treatment with ICl resulted in rapid deglycosylation, anomerization, and isomerization of thymidine and 3-substituted thymidine analogues under various reaction conditions leading to the formation of the nucleobases as the major products accompanied by minor formation of α-furanosidic-, α-pyranosidic- and β-pyranosidic nucleosides. On the other hand, 3,3′,5′-trisubstitued thymidine analogues were only deglycosylated and anomerized. These results are similar to those observed for the acidic hydrolysis of the glycoside bond in nucleosides, but were presumably caused by the Lewis acid character of an iodine electrophile. PMID:25372994

  6. Molecular cloning, functional expression and chromosomal localization of a cDNA encoding a human Na+/nucleoside cotransporter (hCNT2) selective for purine nucleosides and uridine.

    PubMed

    Ritzel, M W; Yao, S Y; Ng, A M; Mackey, J R; Cass, C E; Young, J D

    1998-01-01

    Two Na(+)-dependent nucleoside transporters implicated in adenosine and uridine transport in mammalian cells are distinguished functionally on the basis of substrate specificity: CNT1 is selective for pyrimidine nucleosides but also transports adenosine; CNT2 (also termed SPNT) is selective for purine nucleosides but also transports uridine. Both proteins belong to a gene family that includes the NupC proton/nucleoside symporter of E. coli. cDNAs encoding members of the CNT family have been isolated from rat tissues (jejunum, brain, liver; rCNT1 and rCNT2/SPNT) and, most recently, human kidney (hCNT1 and hSPNT1). Here, the molecular cloning and functional characterization of a CNT2/SPNT-type transporter from human small intestine are described. The encoded 658-residue protein (hCNT2 in the nomenclature) had the same predicted amino acid sequence as human kidney hSPNT1, except for a polymorphism at residue 75 (Arg substituted by Ser), and was 83 and 72% identical to rCNT2 and hCNT1, respectively. Sequence differences between hCNT2 and rCNT2 were greatest at the N-terminus. In Xenopus oocytes, recombinant hCNT2 exhibited the functional characteristics of a Na(+)-dependent nucleoside transporter with selectivity for adenosine, other purine nucleosides and uridine (adenosine and uridine K(m) app values 8 and 40 microM, respectively). hCNT2 transcripts were found in kidney and small intestine but, unlike rCNT2, were not detected in liver. Deoxyadenosine, which undergoes net renal secretion in humans, was less readily transported than adenosine. hCNT2 also mediated small, but significant, fluxes of the antiviral purine nucleoside analogue 2',3'-dideoxyinosine. hCNT2 is, therefore potentially involved in both the intestinal absorption and renal handling of purine nucleosides (including adenosine), uridine and purine nucleoside drugs. The gene encoding hCNT2 was mapped to chromosome 15q15. PMID:10087507

  7. Switching to a Protease Inhibitor–Containing, Nucleoside-Sparing Regimen (Lopinavir/Ritonavir Plus Efavirenz) Increases Limb Fat But Raises Serum Lipid Levels

    PubMed Central

    Tebas, Pablo; Zhang, Jiameng; Yarasheski, Kevin; Evans, Scott; Fischl, Margaret A.; Shevitz, Abby; Feinberg, Judith; Collier, Ann C.; Shikuma, Cecilia; Brizz, Barbara; Sattler, Fred

    2015-01-01

    Background Subcutaneous limb fat loss continues to be one the most troubling side effects of long-term antiretroviral regimens. Nucleoside analogues and protease inhibitors (PIs) have been linked to the development of this complication. Methods We evaluated the effects of nucleoside-sparing and PI-sparing regimens on fat distribution, bone mineral density, and metabolic parameters in 62 subjects, who were not selected for lipoatrophy, with advanced HIV (nadir CD4 count ≤200 cells/mm3 or HIV RNA level ≥80,000 copies/mL) and an undetectable HIV viral load. Participants were randomized to switch their initial successful antiretroviral regimen to open-label lopinavir/ritonavir (LPV/r) at a dose of 533/133 mg twice a day and efavirenz (EFV) at a dose of 600 mg/d (the nucleoside-sparing arm) versus EFV and 2 nucleoside analogues (the PI-sparing arm). Findings At week 48, the median change in limb fat in the nucleoside-sparing arm was 562 g (6%, interquartile range [IQR]: −218–1186 g) versus a loss of −242 g (−4%, IQR: −539–452 g) in the nucleoside-containing PI-sparing arm (P = 0.086). At the time of last observation (median = 102 weeks, IQR: 73–152 weeks), a median gain of 782 g (10%, IQR: −380–1168 g) of limb fat was noted in the nonnucleoside arm (n = 22) versus a loss of 850 g (−15%, IQR: −1270 to −526 g) in the nucleoside-containing arm (n = 25; P = 0.002). Interpretation The switch to a nucleoside-sparing combination antiretroviral regimen (LPV/r + EFV) was associated with significant improvement in limb fat. These results provide additional evidence that nucleoside analogues are important in the progressive limb fat loss that characterizes antiretroviral treatment and that switching medications can significantly improve this complication. This option has to be carefully balanced with the potential to increase serum lipid levels and the trend to increase virologic failure. PMID:17527093

  8. Pharmacological Reversal of Histone Methylation Presensitizes Pancreatic Cancer Cells to Nucleoside Drugs: In Vitro Optimization and Novel Nanoparticle Delivery Studies

    PubMed Central

    Hung, Sau Wai; Bhutia, Yangzom D.; Davis, Franklin; Cho, Jong Hyun; Zastre, Jason; Dhar, Shanta; Chu, Chung K.; Govindarajan, Rajgopal

    2013-01-01

    We evaluated the potential of an investigational histone methylation reversal agent, 3-deazaneplanocin A (DZNep), in improving the chemosensitivity of pancreatic cancer to nucleoside analogs (i.e., gemcitabine). DZNep brought delayed but selective cytotoxicity to pancreatic cancer cells without affecting normal human pancreatic ductal epithelial (HPDE) cells. Co-exposure of DZNep and gemcitabine induced cytotoxic additivity or synergism in both well- and poorly-differentiated pancreatic cell lines by increased apoptosis. In contrast, DZNep exerted antagonism with gemcitabine against HPDE cells with significant reduction in cytotoxicity compared with the gemcitabine-alone regimen. DZNep marginally depended on purine nucleoside transporters for its cytotoxicity, but the transport dependence was circumvented by acyl derivatization. Drug exposure studies revealed that a short priming with DZNep followed by gemcitabine treatment rather than co-treatment of both agents to produce a maximal chemosensitization response in both gemcitabine-sensitive and gemcitabine-resistant pancreatic cancer cells. DZNep rapidly and reversibly decreased trimethylation of histone H3 lysine 27 but increased trimethylation of lysine 9 in an EZH2- and JMJD1A/2C-dependent manner, respectively. However, DZNep potentiation of nucleoside analog chemosensitization was found to be temporally coupled to trimethylation changes in lysine 27 and not lysine 9. Polymeric nanoparticles engineered to chronologically release DZNep followed by gemcitabine produced pronounced chemosensitization and dose-lowering effects. Together, our results identify that an optimized DZNep exposure can presensitize pancreatic cancer cells to anticancer nucleoside analogs through the reversal of histone methylation, emphasizing the promising clinical utilities of epigenetic reversal agents in future pancreatic cancer combination therapies. PMID:23940717

  9. 1'-Homonucleosides and their structural analogues: A review.

    PubMed

    Wróblewski, Andrzej E; Głowacka, Iwona E; Piotrowska, Dorota G

    2016-08-01

    Nucleoside analogues belong to an important class of antiviral and anticancer drugs. Insertion of a methylene fragment between the anomeric carbon and pyrimidine or purine bases transforms nucleosides into 1'-homonucleosides. When compared with nucleosides this modification lengthens the separation between HO-C5' of pentofuranoside fragments and nitrogen (N1 or N9) atoms of nucleobases, lowers the steric and electronic interactions between nucleobases and sugar rings, introduces greater flexibility around a CH2-Base bond and thus allows for more rotational freedom, and since the anomeric effect no longer operates any sugar or pseudosugar moiety exists in its unique conformation and experiences specific conformational mobility and hydrolysis of the C1'-CH2Base bond by cellular enzymes is no longer feasible. This review covers 1'-homonucleosides with a tetrahydrofuran ring and its nitrogen and sulfur analogues as well as those containing a cyclopentane moiety as a sugar replacer. Achievements in syntheses of sugar or pseudosugar scaffolds are of primary interest since pathways to install nucleobases are well recognized. Whenever possible, the biological activity, mostly antiviral and antitumor but sometimes as inhibitors of specific enzymes, will be presented and discussed to help identify structural features responsible for the particular mode of action and thus possible therapeutic significance. PMID:27128178

  10. Prebiotic phosphorylation of nucleosides in formamide

    NASA Technical Reports Server (NTRS)

    Schoffstall, A. M.

    1976-01-01

    Results are presented for an experimental study intended to assess phosphorylation under neither aqueous nor dry thermal conditions. Instead, phosphorylations were attempted in possible nonaqueous prebiotic solvents. Formamide appeared to be the most obvious candidate for phosphorylation studies. Three main classes of phosphorylated products were formed in formamide solution: adenosine monophosphates, cyclic adenosine phosphate, and adenosine diphosphates. Experiments were designed to investigate the extent of phosphorylation of nucleosides in formamide, the relative amounts of nucleoside monophosphate, diphosphates and cyclic phosphate formed and the relative effectiveness of different sources of phosphate as phosphorylating agents in formamide. Reaction variables were temperature, nature of the phosphate or condensed phosphate, nucleoside, concentration of reactants and possible effects of additives. Product identification was based on qualitative and quantitative thin layer chromatography.

  11. Polymeric nanogel formulations of nucleoside analogs

    PubMed Central

    Vinogradov, Serguei V

    2008-01-01

    Nanogels are colloidal microgel carriers that have been introduced recently as a prospective drug delivery system for nucleotide therapeutics. The crosslinked protonated polymer network of nanogels binds oppositely charged drug molecules, encapsulating them into submicron particles with a core-shell structure. The nanogel network also provides a suitable template for chemical engineering, surface modification and vectorisation. This review reveals recent attempts to develop novel drug formulations of nanogels with antiviral and antiproliferative nucleoside analogs in the active form of 5′-triphosphates; discusses structural approaches to the optimisation of nanogel properties, and; discusses the development of targeted nanogel drug formulations for systemic administration. Notably, nanogels can improve the CNS penetration of nucleoside analogs that are otherwise restricted from passing across the blood–brain barrier. The latest findings reviewed here demonstrate an efficient intracellular release of nucleoside analogs, encouraging further applications of nanogel carriers for targeted drug delivery. PMID:17184158

  12. Three Efficient Methods for Preparation of Coelenterazine Analogues.

    PubMed

    Shakhmin, Anton; Hall, Mary P; Walker, Joel R; Machleidt, Thomas; Binkowski, Brock F; Wood, Keith V; Kirkland, Thomas A

    2016-07-18

    The growing popularity of bioluminescent assays has highlighted the need for coelenterazine analogues possessing properties tuned for specific applications. However, the structural diversity of known coelenterazine analogues has been limited by current syntheses. Known routes for the preparation of coelenterazine analogues employ harsh reaction conditions that limit access to many substituents and functional groups. Novel synthetic routes reported here establish simple and robust methods for synthesis and investigation of structurally diverse marine luciferase substrates. Specifically, these new routes allow synthesis of coelenterazine analogues containing various heterocyclic motifs and substituted aromatic groups with diverse electronic substituents at the R(2) position. Interesting analogues described herein were characterized by their physicochemical properties, bioluminescent half-life, light output, polarity and cytotoxicity. Some of the analogues represent leads that can be utilized in the development of improved bioluminescent systems. PMID:27305599

  13. Synthesis of Nucleoside Triphosphates from 2'-3'-Protected Nucleosides Using Trimetaphosphate.

    PubMed

    Mohamady, Samy; Taylor, Scott D

    2016-02-01

    Chemists have been attempting to triphosphorylate nucleosides and other alcohols using trimetaphosphate (TriMP) since the 1960s. However, this route appears to have been abandoned due to poor yields. The first practical syntheses of nucleoside triphosphates (NTPs) are reported using TriMP as the key reagent. This was achieved by reacting the tetrabutylammonium salt of TriMP with mesitylenesulfonyl chloride in the presence of DABCO in pyridine followed by the addition of an appropriately protected nucleoside and phthalimide. Quenching the reaction with aqueous buffer followed by hydrolysis of the OH protecting groups gave the NTPs in good yield. PMID:26759914

  14. Cell-cycle-dependent regulation of CNT1, a concentrative nucleoside transporter involved in the uptake of cell-cycle-dependent nucleoside-derived anticancer drugs.

    PubMed

    Valdés, Raquel; Casado, F Javier; Pastor-Anglada, Marçal

    2002-08-23

    Most nucleoside-derived anticancer drugs are taken up by the high-affinity Na-dependent nucleoside transporter CNT1. Since such drugs are to some extent cell-cycle-dependent in their cytotoxic action, we examined the relationship between CNT1 expression and cell-cycle progression in the rat hepatoma cell line FAO. Cell cultures were synchronized either at late G1 or early S stages by combining mimosin treatment with either previous synchronization or not by serum starvation. Cell-cycle progression was then assessed by measuring [methyl-3H]thymidine incorporation into DNA and monitoring cyclin E and A protein levels. In these conditions, CNT1 protein amounts increase at the G1-S transition. When cells were synchronized using hydroxyurea (HU), which directly interacts with nucleotide metabolism by inhibiting ribonucleotide reductase, CNT1 protein amounts increased in synchronized cells and remained high during cell-cycle progression. These data indicate that CNT1 adapts to cell-cycle progression and responds to nucleos(t)ide metabolism status, a feature that might contribute to the cytotoxic action of cell-cycle-dependent anticancer drugs. PMID:12176019

  15. Pseudobond parameters for QM/MM studies involving nucleosides, nucleotides, and their analogs

    SciTech Connect

    Chaudret, Robin; Parks, Jerry M; Yang, Weitao

    2013-01-01

    In biological systems involving nucleosides, nucleotides, or their respective analogs, the ribose sugar moiety is the most common reaction site, for example, during DNA replication and repair. How- ever, nucleic bases, which comprise a sizable portion of nucleotide molecules, are usually unreactive during such processes. In quantum mechanical/molecular simulations of nucleic acid reactivity, it may therefore be advantageous to describe specific ribosyl or ribosyl phosphate groups quantum me- chanically and their respective nucleic bases with a molecular mechanics potential function. Here, we have extended the pseudobond approach to enable quantum mechanical/molecular mechanical simulations involving nucleotides, nucleosides, and their analogs in which the interface between the two subsystems is located between the sugar and the base, namely, the C(sp3) N(sp2) bond. The pseudobond parameters were optimized on a training set of 10 molecules representing several nu- cleotide and nucleoside bases and analogs, and they were then tested on a larger test set of 20 diverse molecules. Particular emphasis was placed on providing accurate geometries and electrostatic prop- erties, including electrostatic potential, natural bond orbital (NBO) and atoms in molecules (AIM) charges and AIM first moments. We also tested the optimized parameters on five nucleotide and nu- cleoside analogues of pharmaceutical relevance and a small polypeptide (triglycine). Accuracy was maintained for these systems, which highlights the generality and transferability of the pseudobond approach. 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772182

  16. Targeted Delivery of Deoxycytidine Kinase to Her2-Positive Cells Enhances the Efficacy of the Nucleoside Analog Fludarabine

    PubMed Central

    Kay, Brian K.; Lavie, Arnon

    2016-01-01

    Cytotoxic drugs, such as nucleoside analogs and toxins, commonly suffer from off-target effects. One approach to mitigate this problem is to deliver the cytotoxic drug selectively to the intended site. While for toxins this can be achieved by conjugating the cell-killing moiety to a targeting moiety, it is not an option for nucleoside analogs, which rely on intracellular enzymes to convert them to their active triphosphorylated form. To overcome this limitation, and achieve site-targeted activation of nucleoside analogs, we fused the coding region of a prodrug-activating enzyme, deoxycytidine kinase (dCK), to affinity reagents that bind to the Her2 cell surface protein. We evaluated dCK fusions to an anti-Her2 affibody and Designed Ankyrin Repeat Protein (DARPin) for their ability to kill cancer cells by promoting the activation of the nucleoside analog fludarabine. Cell staining and flow cytometry experiments with three Her2 positive cancer cell lines (BT-474-JB, JIMT-1 and SK-OV-3) indicate dCK fusions binding and cellular internalization. In contrast, these reagents bind only weakly to the Her2 negative cell line, MCF-7. Cell proliferation assays indicate that SK-OV-3 and BT-474-JB cell lines exhibit significantly reduced proliferation rates when treated with targeting-module fused dCK and fludarabine, compared to fludarabine alone. These findings demonstrate that we have succeeded in delivering active dCK into the Her2-positive cells, thereby increasing the activation of fludarabine, which ultimately reduces the dose of nucleoside analog needed for cell killing. This strategy may help establish the therapeutic index required to differentiate between healthy tissues and cancer cells. PMID:27280468

  17. Structural analogues of diosgenyl saponins: synthesis and anticancer activity.

    PubMed

    Kaskiw, Matthew J; Tassotto, Mary Lynn; Mok, Mac; Tokar, Stacey L; Pycko, Roxanne; Th'ng, John; Jiang, Zi-Hua

    2009-11-15

    Saponins display various biological activities including anti-tumor activity. Recently intensive research has been focused on developing saponins for tumor therapies. The diosgenyl saponin dioscin is one of the most common steroidal saponins and exhibits potent anticancer activity in several human cancer cells through apoptosis-inducing pathways. In this paper, we describe the synthesis of several diosgenyl saponin analogues containing either a 2-amino-2-deoxy-beta-d-glucopyranosyl residue or an alpha-l-rhamnopyranosyl-(1-->4)-2-amino-2-deoxy-beta-d-glucopyranosyl residue with different acyl substituents on the amino group. The cytotoxic activity of these compounds was evaluated in MCF-7 breast cancer cells and HeLa cervical cancer cells. Structure-activity relationship studies show that the disaccharide saponin analogues are in general less active than their corresponding monosaccharide analogues. The incorporation of an aromatic nitro functionality into these saponin analogues does not exhibit significant effect on their cytotoxic activity. PMID:19819703

  18. Basolateral Uptake of Nucleosides by Sertoli Cells Is Mediated Primarily by Equilibrative Nucleoside Transporter 1

    PubMed Central

    Klein, David M.; Evans, Kristen K.; Hardwick, Rhiannon N.; Dantzler, William H.; Wright, Stephen H.

    2013-01-01

    The blood-testis barrier (BTB) prevents the entry of many xenobiotic compounds into seminiferous tubules thereby protecting developing germ cells. Understanding drug transport across the BTB may improve drug delivery into the testis. Members of one class of drug, nucleoside reverse transcriptase inhibitors (NRTIs), do penetrate the BTB, presumably through interaction with physiologic nucleoside transporters. By investigating the mechanism of nucleoside transport, it may be possible to design other drugs to bypass the BTB in a similar manner. We present a novel ex vivo technique to study transport at the BTB that employs isolated, intact seminiferous tubules. Using this system, we found that over 80% of total uptake by seminiferous tubules of the model nucleoside uridine could be inhibited by 100 nM nitrobenzylmercaptopurine riboside (NBMPR, 6-S-[(4-nitrophenyl)methyl]-6-thioinosine), a concentration that selectively inhibits equilibrative nucleoside transporter 1 (ENT1) activity. In primary cultured rat Sertoli cells, 100 nM NBMPR inhibited all transepithelial transport and basolateral uptake of uridine. Immunohistochemical staining showed ENT1 to be located on the basolateral membrane of human and rat Sertoli cells, whereas ENT2 was located on the apical membrane of Sertoli cells. Transepithelial transport of uridine by rat Sertoli cells was partially inhibited by the NRTIs zidovudine, didanosine, and tenofovir disoproxil fumarate, consistent with an interaction between these drugs and ENT transporters. These data indicate that ENT1 is the primary route for basolateral nucleoside uptake into Sertoli cells and a possible mechanism for nucleosides and nucleoside-based drugs to undergo transepithelial transport. PMID:23639800

  19. New hypoxanthine nucleosides with RNA antiviral activity.

    PubMed

    Nair, V; Ussery, M A

    1992-08-01

    A series of novel C-2 functionalized hypoxanthine and purine ribonucleosides have been synthesized and evaluated against exotic RNA viruses of the family or genus alpha, arena, flavi, and rhabdo. Both specific and broad-spectrum antiviral activities were discovered but only with hypoxanthine nucleosides. PMID:1444325

  20. Nucleoside phosphorylation by the mineral schreibersite

    PubMed Central

    Gull, Maheen; Mojica, Mike A.; Fernández, Facundo M.; Gaul, David A.; Orlando, Thomas M.; Liotta, Charles L.; Pasek, Matthew A.

    2015-01-01

    Phosphorylation of the nucleosides adenosine and uridine by the simple mixing and mild heating of aqueous solutions of the organic compounds with synthetic analogs of the meteoritic mineral schreibersite, (Fe,Ni)3P under slightly basic conditions (pH ~9) is reported. These results suggest a potential role for meteoritic phosphorus in the origin and development of early life. PMID:26606901

  1. Dolastatin 11 conformations, analogues and pharmacophore.

    PubMed

    Ali, Md Ahad; Bates, Robert B; Crane, Zackary D; Dicus, Christopher W; Gramme, Michelle R; Hamel, Ernest; Marcischak, Jacob; Martinez, David S; McClure, Kelly J; Nakkiew, Pichaya; Pettit, George R; Stessman, Chad C; Sufi, Bilal A; Yarick, Gayle V

    2005-07-01

    Twenty analogues of the natural antitumor agent dolastatin 11, including majusculamide C, were synthesized and tested for cytotoxicity against human cancer cells and stimulation of actin polymerization. Only analogues containing the 30-membered ring were active. Molecular modeling and NMR evidence showed the low-energy conformations. The amide bonds are all trans except for the one between the Tyr and Val units, which is cis. Since an analogue restricted to negative 2-3-4-5 angles stimulated actin polymerization but was inactive in cells, the binding conformation (most likely the lowest-energy conformation in water) has a negative 2-3-4-5 angle, whereas a conformation with a positive 2-3-4-5 angle (most likely the lowest energy conformation in chloroform) goes through cell walls. The highly active R alcohol from borohydride reduction of dolastatin 11 is a candidate for conversion to prodrugs. PMID:15878670

  2. Identification of a nucleoside/nucleobase transporter from Plasmodium falciparum, a novel target for anti-malarial chemotherapy.

    PubMed Central

    Parker, M D; Hyde, R J; Yao, S Y; McRobert, L; Cass, C E; Young, J D; McConkey, G A; Baldwin, S A

    2000-01-01

    Plasmodium, the aetiologic agent of malaria, cannot synthesize purines de novo, and hence depends upon salvage from the host. Here we describe the molecular cloning and functional expression in Xenopus oocytes of the first purine transporter to be identified in this parasite. This 422-residue protein, which we designate PfENT1, is predicted to contain 11 membrane-spanning segments and is a distantly related member of the widely distributed eukaryotic protein family the equilibrative nucleoside transporters (ENTs). However, it differs profoundly at the sequence and functional levels from its homologous counterparts in the human host. The parasite protein exhibits a broad substrate specificity for natural nucleosides, but transports the purine nucleoside adenosine with a considerably higher apparent affinity (K(m) 0.32+/-0.05 mM) than the pyrimidine nucleoside uridine (K(m) 3.5+/-1.1 mM). It also efficiently transports nucleobases such as adenine (K(m) 0.32+/-0.10 mM) and hypoxanthine (K(m) 0.41+/-0.1 mM), and anti-viral 3'-deoxynucleoside analogues. Moreover, it is not sensitive to classical inhibitors of mammalian ENTs, including NBMPR [6-[(4-nitrobenzyl)thio]-9-beta-D-ribofuranosylpurine, or nitrobenzylthioinosine] and the coronary vasoactive drugs, dipyridamole, dilazep and draflazine. These unique properties suggest that PfENT1 might be a viable target for the development of novel anti-malarial drugs. PMID:10861212

  3. Identification of a nucleoside triphosphate binding site on calf thymus RNA polymerase II

    SciTech Connect

    Freund, E.; McGuire, P.M.

    1986-01-14

    A nucleoside triphosphate binding site on calf thymus RNA polymerase II was identified by using photoaffinity analogues of adenosine 5'-triphosphate and guanosine 5'-triphosphate. Both radiolabeled 8-azidoadenosine 5'-triphosphate (8-N3ATP) and radiolabeled 8-azidoguanosine 5'-triphosphate (8-N3GTP) bound to a single polypeptide of this enzyme. This polypeptide has a molecular mass of 37 kilodaltons and an isoelectric point of 5.4. Ultraviolet (UV) irradiation was necessary for photolabeling to occur. In addition, no labeling occurred when the probe was prephotolyzed or when the enzyme was inactivated. Furthermore, photolabeling of the enzyme could be decreased by preincubation with natural substrates. To provide evidence that the radiolabeled polypeptide forms a part of the domain of the nucleoside triphosphate binding site, experiments were performed using unlabeled 8-N3ATP. Although this unlabeled analogue was not a substrate for RNA polymerase II, it photoinactivated the enzyme in the presence of UV irradiation, and it inhibited transcription elongation by the enzyme in a competitive manner in the absence of UV irradiation. As in the case with photolabeling, photoinactivation by 8-N3ATP could be decreased by natural substrates; in both cases, purine ribonucleoside triphosphates were more efficient than pyrimidine nucleoside triphosphates. Furthermore, photoinactivation was saturable at about the same concentration as the inhibition constant for 8-N3ATP. Collectively, these results provide evidence that the radiolabeled polypeptide in calf thymus RNA polymerase II is an essential component for activity and suggest that this polypeptide may be part of this enzyme's purine ribonucleoside triphosphate binding site.

  4. Characterization of nucleoside transport systems in cultured rat epididymal epithelium.

    PubMed

    Leung, G P; Ward, J L; Wong, P Y; Tse, C M

    2001-05-01

    The nucleoside transport systems in cultured epididymal epithelium were characterized and found to be similar between the proximal (caput and corpus) and distal (cauda) regions of the epididymis. Functional studies revealed that 70% of the total nucleoside uptake was Na(+) dependent, while 30% was Na(+) independent. The Na(+)-independent nucleoside transport was mediated by both the equilibrative nitrobenzylthioinosine (NBMPR)-sensitive system (40%) and the NBMPR-insensitive system (60%), which was supported by a biphasic dose response to NBMPR inhibition. The Na(+)-dependent [(3)H]uridine uptake was selectively inhibited 80% by purine nucleosides, indicating that the purine nucleoside-selective N1 system is predominant. Since Na(+)-dependent [(3)H]guanosine uptake was inhibited by thymidine by 20% and Na(+)-dependent [(3)H]thymidine uptake was broadly inhibited by purine and pyrimidine nucleosides, this suggested the presence of the broadly selective N3 system accounting for 20% of Na(+)-dependent nucleoside uptake. Results of RT-PCR confirmed the presence of mRNA for equilibrative nucleoside transporter (ENT) 1, ENT2, and concentrative nucleoside transporter (CNT) 2 and the absence of CNT1. It is suggested that the nucleoside transporters in epididymis may be important for sperm maturation by regulating the extracellular concentration of adenosine in epididymal plasma. PMID:11287319

  5. Synthesis, antiarrhythmic activity, and toxicological evaluation of mexiletine analogues.

    PubMed

    Roselli, Mariagrazia; Carocci, Alessia; Budriesi, Roberta; Micucci, Matteo; Toma, Maddalena; Di Cesare Mannelli, Lorenzo; Lovece, Angelo; Catalano, Alessia; Cavalluzzi, Maria Maddalena; Bruno, Claudio; De Palma, Annalisa; Contino, Marialessandra; Perrone, Maria Grazia; Colabufo, Nicola Antonio; Chiarini, Alberto; Franchini, Carlo; Ghelardini, Carla; Habtemariam, Solomon; Lentini, Giovanni

    2016-10-01

    Four mexiletine analogues have been tested for their antiarrhythmic, inotropic, and chronotropic effects on isolated guinea pig heart tissues and to assess calcium antagonist activity, in comparison with the parent compound mexiletine. All analogues showed from moderate to high antiarrhythmic activity. In particular, three of them (1b,c,e) were more active and potent than the reference drug, while exhibiting only modest or no negative inotropic and chronotropic effects and vasorelaxant activity, thus showing high selectivity of action. All compounds showed no cytotoxicity and 1b,c,d did not impair motor coordination. All in, these new analogues exhibit an interesting cardiovascular profile and deserve further investigation. PMID:27267000

  6. Nucleoside azide-alkyne cycloaddition reactions under solvothermal conditions or using copper vials in a ball mill.

    PubMed

    Cummings, Andrew J; Ravalico, Francesco; McColgan-Bannon, Kegan I S; Eguaogie, Olga; Elliott, P Alain; Shannon, Matthew R; Bermejo, Iris A; Dwyer, Angus; Maginty, Amanda B; Mack, James; Vyle, Joseph S

    2015-01-01

    Novel nucleoside analogues containing photoswitchable moieties were prepared using 'click' cycloaddition reactions between 5'-azido-5'-deoxythymidine and mono- or bis-N-propargylamide-substituted azobenzenes. In solution, high to quantitative yields were achieved using 5 mol% Cu(I) in the presence of a stabilizing ligand. 'Click' reactions using the monopropargylamides were also effected in the absence of added cuprous salts by the application of liquid assisted grinding (LAG) in metallic copper reaction vials. Specifically, high speed vibration ball milling (HSVBM) using a 3/32″ (2.38 mm) diameter copper ball (62 mg) at 60 Hz overnight in the presence of ethyl acetate lead to complete consumption of the 5'-azido nucleoside with clean conversion to the corresponding 1,3-triazole. PMID:25874944

  7. Syntheses of 5'-Nucleoside Monophosphate Derivatives with Unique Aminal, Hemiaminal, and Hemithioaminal Functionalities: A New Class of 5'-Peptidyl Nucleotides.

    PubMed

    De, Swarup; Groaz, Elisabetta; Margamuljana, Lia; Herdewijn, Piet

    2016-06-01

    A number of synthetically useful transformations have been developed to generate novel 5'-peptidyl nucleoside monophosphate analogues that incorporate sensitive phosphoaminal, -hemiaminal or -hemithioaminal functionalities. The strategies adopted entailed the coupling between dipeptides, which enclose a reactive Cα-functionalized glycine residue and phosphate or phosphorothioate moieties. These developments led to potentially powerful and general methodologies for the preparation of α-phosphorylated pseudopeptides as well as nucleoside monophosphate mimics. The resulting conjugates are of interest for a variety of important applications, which range from drug development to synthetic biology, as pronucleotides or artificial building blocks for the enzymatic synthesis of xenobiotic information systems. The potential of all dipeptide-TMP conjugates as pyrophosphate mimics in the DNA polymerization reaction was tested, and the influence of the nature of the linker was evaluated by in vitro chain elongation assay in the presence of wild-type microbial DNA polymerases. PMID:27136602

  8. Synthesis of chamaecypanone C analogues from in situ-generated cyclopentadienones and their biological evaluation.

    PubMed

    Dong, Suwei; Qin, Tian; Hamel, Ernest; Beutler, John A; Porco, John A

    2012-12-01

    A rhodium-catalyzed dehydrogenation protocol for the conversion of 3,5-diarylcyclopentenones to the corresponding 2,4-diarylcyclopentadienones has been developed. With this protocol, analogues of the cytotoxic agent chamaecypanone C have been synthesized via Diels-Alder cycloaddition between the cyclopentadienones and in situ-generated o-quinols. Biological evaluation of these analogues revealed a compound with higher activity as a microtubule inhibitor and cytotoxic agent in comparison with the parent structure. PMID:23110297

  9. Synthesis of Chamaecypanone C Analogues from in situ-Generated Cyclopentadienones and their Biological Evaluation

    PubMed Central

    Dong, Suwei; Qin, Tian; Hamel, Ernest; Beutler, John A.; Porco, John A.

    2012-01-01

    A rhodium-catalyzed dehydrogenation protocol has been developed for conversion of 3,5-diarylcyclopentenones to the corresponding 2,4-diarylcyclopentadienones. Using this protocol, analogues of the cytotoxic agent chamaecypanone C have been synthesized via Diels-Alder cycloaddition between the cyclopentadienones and in situ-generated ortho-quinols. Biological evaluation of these analogues revealed a compound with higher activity as a microtubule inhibitor and cytotoxic agent in comparison with the parent structure. PMID:23110297

  10. Human cytomegalovirus resistance to deoxyribosylindole nucleosides maps to a transversion mutation in the terminase subunit-encoding gene UL89.

    PubMed

    Gentry, Brian G; Phan, Quang; Hall, Ellie D; Breitenbach, Julie M; Borysko, Katherine Z; Kamil, Jeremy P; Townsend, Leroy B; Drach, John C

    2015-01-01

    Human cytomegalovirus (HCMV) infection can cause severe illnesses, including encephalopathy and mental retardation, in immunocompromised and immunologically immature patients. Current pharmacotherapies for treating systemic HCMV infections include ganciclovir, cidofovir, and foscarnet. However, long-term administration of these agents can result in serious adverse effects (myelosuppression and/or nephrotoxicity) and the development of viral strains with reduced susceptibility to drugs. The deoxyribosylindole (indole) nucleosides demonstrate a 20-fold greater activity in vitro (the drug concentration at which 50% of the number of plaques was reduced with the presence of drug compared to the number in the absence of drug [EC50] = 0.34 μM) than ganciclovir (EC50 = 7.4 μM) without any observed increase in cytotoxicity. Based on structural similarity to the benzimidazole nucleosides, we hypothesize that the indole nucleosides target the HCMV terminase, an enzyme responsible for packaging viral DNA into capsids and cleaving the DNA into genome-length units. To test this hypothesis, an indole nucleoside-resistant HCMV strain was isolated, the open reading frames of the genes that encode the viral terminase were sequenced, and a G766C mutation in exon 1 of UL89 was identified; this mutation resulted in an E256Q change in the amino acid sequence of the corresponding protein. An HCMV wild-type strain, engineered with this mutation to confirm resistance, demonstrated an 18-fold decrease in susceptibility to the indole nucleosides (EC50 = 3.1 ± 0.7 μM) compared to that of wild-type virus (EC50 = 0.17 ± 0.04 μM). Interestingly, this mutation did not confer resistance to the benzimidazole nucleosides (EC50 for wild-type HCMV = 0.25 ± 0.04 μM, EC50 for HCMV pUL89 E256Q = 0.23 ± 0.04 μM). We conclude, therefore, that the G766C mutation that results in the E256Q substitution is unique for indole nucleoside resistance and distinct from previously discovered substitutions

  11. Summary: the modified nucleosides of RNA.

    PubMed Central

    Limbach, P A; Crain, P F; McCloskey, J A

    1994-01-01

    A comprehensive listing is made of posttranscriptionally modified nucleosides from RNA reported in the literature through mid-1994. Included are chemical structures, common names, symbols, Chemical Abstracts registry numbers (for ribonucleoside and corresponding base), Chemical Abstracts Index Name, phylogenetic sources, and initial literature citations for structural characterization or occurrence, and for chemical synthesis. The listing is categorized by type of RNA: tRNA, rRNA, mRNA, snRNA, and other RNAs. A total of 93 different modified nucleosides have been reported in RNA, with the largest number and greatest structural diversity in tRNA, 79; and 28 in rRNA, 12 in mRNA, 11 in snRNA and 3 in other small RNAs. PMID:7518580

  12. An alternative route to the arylvinyltriazole nucleosides.

    PubMed

    Chudinov, Mikhail V; Prutkov, Alexander N; Matveev, Andrey V; Grebenkina, Lyubov E; Konstantinova, Irina D; Berezovskaya, Yulia V

    2016-07-15

    A new pathway to synthesis of arylvinyl ribavirin analogues is developed which makes it possible to obtain not only trans- but also cis-isomers at vinyl bond. By this route eight ribavirin 5-arylvinyl analogues are synthesized and their antiviral activity is evaluated. PMID:27262598

  13. 2'-modified nucleosides for site-specific labeling of oligonucleotides

    NASA Technical Reports Server (NTRS)

    Krider, Elizabeth S.; Miller, Jeremiah E.; Meade, Thomas J.

    2002-01-01

    We report the synthesis of 2'-modified nucleosides designed specifically for incorporating labels into oligonucleotides. Conversion of these nucleosides to phosphoramidite and solid support-bound derivatives proceeds in good yield. Large-scale synthesis of 11-mer oligonucleotides possessing the 2'-modified nucleosides is achieved using these derivatives. Thermal denaturation studies indicate that the presence of 2'-modified nucleosides in 11-mer duplexes has minimal destabilizing effects on the duplex structure when the nucleosides are placed at the duplex termini. The powerful combination of phosphoramidite and support-bound derivatives of 2'-modified nucleosides affords the large-scale preparation of an entirely new class of oligonucleotides. The ability to synthesize oligonucleotides containing label attachment sites at 3', intervening, and 5' locations of a duplex is a significant advance in the development of oligonucleotide conjugates.

  14. Unusual tubulin-clustering ability of specifically c7-modified colchicine analogues.

    PubMed

    Zefirova, Olga N; Lemcke, Heiko; Lantow, Margareta; Nurieva, Evgeniya V; Wobith, Birgit; Onishchenko, Galina E; Hoenen, Antje; Griffiths, Gareth; Zefirov, Nikolay S; Kuznetsov, Sergei A

    2013-08-19

    Highly cytotoxic C7-modified colchicine analogues, exemplified by tubuloclustin, promote microtubule disassembly followed by the formation of very stable tubulin clusters, both in vitro and in cells. The proposed mechanism of action of tubuloclustin and its analogues, beyond that of colchicine, includes additional specific interactions with the α-tubulin subunit. PMID:23843347

  15. Purine (N)-Methanocarba Nucleoside Derivatives Lacking an Exocyclic Amine as Selective A3 Adenosine Receptor Agonists.

    PubMed

    Tosh, Dilip K; Ciancetta, Antonella; Warnick, Eugene; O'Connor, Robert; Chen, Zhoumou; Gizewski, Elizabeth; Crane, Steven; Gao, Zhan-Guo; Auchampach, John A; Salvemini, Daniela; Jacobson, Kenneth A

    2016-04-14

    Purine (N)-methanocarba-5'-N-alkyluronamidoriboside A3 adenosine receptor (A3AR) agonists lacking an exocyclic amine resulted from an unexpected reaction during a Sonogashira coupling and subsequent aminolysis. Because the initial C6-Me and C6-styryl derivatives had unexpectedly high A3AR affinity, other rigid nucleoside analogues lacking an exocyclic amine were prepared. Of these, the C6-Me-(2-phenylethynyl) and C2-(5-chlorothienylethynyl) analogues were particularly potent, with human A3AR Ki values of 6 and 42 nM, respectively. Additionally, the C2-(5-chlorothienyl)-6-H analogue was potent and selective at A3AR (MRS7220, Ki 60 nM) and also completely reversed mouse sciatic nerve mechanoallodynia (in vivo, 3 μmol/kg, po). The lack of a C6 H-bond donor while maintaining A3AR affinity and efficacy could be rationalized by homology modeling and docking of these hypermodified nucleosides. The modeling suggests that a suitable combination of stabilizing features can partially compensate for the lack of an exocyclic amine, an otherwise important contributor to recognition in the A3AR binding site. PMID:26890707

  16. Nucleoside transport in primary cultured rabbit tracheal epithelial cells.

    PubMed

    Mathias, Neil R; Wu, Sharon K; Kim, Kwang-Jin; Lee, Vincent H L

    2005-01-01

    The present study aimed at elucidating the mechanisms of nucleoside transport in primary cultured rabbit tracheal epithelial cells (RTEC) grown on a permeable filter support. Uptake of (3)H-uridine, the model nucleoside substrate, from the apical fluid of primary cultured RTEC was examined with respect to its dependence on Na(+), substrate concentration, temperature and its sensitivity to inhibitors, other nucleosides and antiviral nucleoside analogs. Apical (3)H-uridine uptake in primary cultured RTEC was strongly dependent on an inward Na(+) gradient and temperature. Ten micromolar nitro-benzyl-mercapto-purine-ribose (NBMPR) (an inhibitor of es-type nucleoside transport in the nanomolar range) did not further inhibit this process. (3)H-uridine uptake from apical fluid was inhibited by basolateral ouabain (10 microM) and apical phloridzin (100 microM), indicating that uptake may involve a secondary active transport process. Uridine uptake was saturable with a K(m) of 3.4 +/- 1.8 microM and the V(max) of 24.3 +/- 5.2 pmoles/mg protein/30 s. Inhibition studies indicated that nucleoside analogs that have a substitution on the nucleobase competed with uridine uptake from apical fluid, but those with modifications on the ribose sugar including acyclic analogs were ineffective. The pattern of inhibition of apical (3)H-uridine, (3)H-inosine and (3)H-thymidine uptake into RTEC cells by physiological nucleosides was consistent with multiple systems: A pyrimidine-selective transport system (CNT1); a broad nucleoside substrate transport system that excludes inosine (CNT4) and an equilibrative NBMPR-insensitive nucleoside transport system (ei type). These results indicate that the presence of apically located nucleoside transporters in the epithelial cells lining the upper respiratory tract can lead to a high accumulation of nucleosides in the trachea. At least one Na(+)-dependent, secondary, active transport process may mediate the apical absorption of nucleosides or

  17. Amphiphilic Tobramycin Analogues as Antibacterial and Antifungal Agents

    PubMed Central

    Shrestha, Sanjib K.; Fosso, Marina Y.; Green, Keith D.

    2015-01-01

    In this study, we investigated the in vitro antifungal activities, cytotoxicities, and membrane-disruptive actions of amphiphilic tobramycin (TOB) analogues. The antifungal activities were established by determination of MIC values and in time-kill studies. Cytotoxicity was evaluated in mammalian cell lines. The fungal membrane-disruptive action of these analogues was studied by using the membrane-impermeable dye propidium iodide. TOB analogues bearing a linear alkyl chain at their 6″-position in a thioether linkage exhibited chain length-dependent antifungal activities. Analogues with C12 and C14 chains showed promising antifungal activities against tested fungal strains, with MIC values ranging from 1.95 to 62.5 mg/liter and 1.95 to 7.8 mg/liter, respectively. However, C4, C6, and C8 TOB analogues and TOB itself exhibited little to no antifungal activity. Fifty percent inhibitory concentrations (IC50s) for the most potent TOB analogues (C12 and C14) against A549 and Beas 2B cells were 4- to 64-fold and 32- to 64-fold higher, respectively, than their antifungal MIC values against various fungi. Unlike conventional aminoglycoside antibiotics, TOB analogues with alkyl chain lengths of C12 and C14 appear to inhibit fungi by inducing apoptosis and disrupting the fungal membrane as a novel mechanism of action. Amphiphilic TOB analogues showed broad-spectrum antifungal activities with minimal mammalian cell cytotoxicity. This study provides novel lead compounds for the development of antifungal drugs. PMID:26033722

  18. Nonenzymatic template-directed reactions on altritol oligomers, preorganized analogues of oligonucleotides

    NASA Technical Reports Server (NTRS)

    Kozlov, I. A.; Zielinski, M.; Allart, B.; Kerremans, L.; Van Aerschot, A.; Busson, R.; Herdewijn, P.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    2000-01-01

    Altritol nucleic acids (ANAs) are RNA analogues with a phosphorylated D-altritol backbone. The nucleobase is attached at the 2-(S)-position of the carbohydrate moiety. We report that ANA oligomers are superior to the corresponding DNA, RNA, and HNA (hexitol nucleic acid) in supporting efficient nonenzymatic template-directed synthesis of complementary RNAs from nucleoside-5'-phosphoro-2-methyl imidazolides. Activated ANA and HNA monomers do not oligomerize efficiently on DNA, RNA, HNA, or ANA templates.

  19. Internalization of nucleoside phosphates into live cells by complex formation with different CPPs and JBS-nucleoducin.

    PubMed

    Mussbach, Franziska; Pietrucha, Regina; Schaefer, Buerk; Reissmann, Siegmund

    2011-01-01

    Nucleoside phosphates can bind to many functional proteins like G-proteins or other GTP-binding proteins in signal transduction or translation processes. Till now internalization of nucleoside phosphates into live cells remains a challenge. We study the internalization of a fluorescent-labelled deoxyuridine triphosphate into HeLa cells and other adhesion and suspension cells. We use different cell-penetrating peptides and a cocktail suitable for formation of non-covalent complexes with the nucleotide. Internalization is observed by fluorescence microscopy, and the uptake efficiency is quantitatively estimated by fluorescence spectroscopy. The applied concentrations of CPPs and the cocktail were checked on cell viability (MTT test) and membrane integrity (bioluminescence test with peptidyl-luciferin), indicating that the CPPs and the complexes with the nucleotide are cytotoxic above certain concentrations. These concentrations depend on CPP and cell type and are the limiting factors for the cargo uptake. PMID:21053144

  20. Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

    PubMed Central

    Brulikova, Lucie

    2011-01-01

    Summary This review article summarizes the results of a long-term investigation of 5-alkoxymethyluracil analogues and is aimed, in particular, at methods of syntheses. Most of the presented compounds were synthesized in order to evaluate their biological activity, therefore, a brief survey of biological activity, especially antiviral, cytotoxic and antibacterial, is also reported. PMID:21804865

  1. The chemoenzymatic synthesis of clofarabine and related 2'-deoxyfluoroarabinosyl nucleosides: the electronic and stereochemical factors determining substrate recognition by E. coli nucleoside phosphorylases.

    PubMed

    Fateev, Ilja V; Antonov, Konstantin V; Konstantinova, Irina D; Muravyova, Tatyana I; Seela, Frank; Esipov, Roman S; Miroshnikov, Anatoly I; Mikhailopulo, Igor A

    2014-01-01

    Two approaches to the synthesis of 2-chloro-9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)adenine (1, clofarabine) were studied. The first approach consists in the chemical synthesis of 2-deoxy-2-fluoro-α-D-arabinofuranose-1-phosphate (12a, (2F)Ara-1P) via three step conversion of 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-α-D-arabinofuranose (9) into the phosphate 12a without isolation of intermediary products. Condensation of 12a with 2-chloroadenine catalyzed by the recombinant E. coli purine nucleoside phosphorylase (PNP) resulted in the formation of clofarabine in 67% yield. The reaction was also studied with a number of purine bases (2-aminoadenine and hypoxanthine), their analogues (5-aza-7-deazaguanine and 8-aza-7-deazahypoxanthine) and thymine. The results were compared with those of a similar reaction with α-D-arabinofuranose-1-phosphate (13a, Ara-1P). Differences of the reactivity of various substrates were analyzed by ab initio calculations in terms of the electronic structure (natural purines vs analogues) and stereochemical features ((2F)Ara-1P vs Ara-1P) of the studied compounds to determine the substrate recognition by E. coli nucleoside phosphorylases. The second approach starts with the cascade one-pot enzymatic transformation of 2-deoxy-2-fluoro-D-arabinose into the phosphate 12a, followed by its condensation with 2-chloroadenine thereby affording clofarabine in ca. 48% yield in 24 h. The following recombinant E. coli enzymes catalyze the sequential conversion of 2-deoxy-2-fluoro-D-arabinose into the phosphate 12a: ribokinase (2-deoxy-2-fluoro-D-arabinofuranose-5-phosphate), phosphopentomutase (PPN; no 1,6-diphosphates of D-hexoses as co-factors required) (12a), and finally PNP. The substrate activities of D-arabinose, D-ribose and D-xylose in the similar cascade syntheses of the relevant 2-chloroadenine nucleosides were studied and compared with the activities of 2-deoxy-2-fluoro-D-arabinose. As expected, D-ribose exhibited the best substrate activity

  2. Cytotoxic Terpene Quinones from Marine Sponges

    PubMed Central

    Gordaliza, Marina

    2010-01-01

    The 1,4-benzoquinone moiety is a common structural feature in a large number of compounds that have received considerable attention owing to their broad spectrum of biological activities. The cytotoxic and antiproliferative properties of many natural sesquiterpene quinones and hydroquinones from sponges of the order Dictyoceratida, such as avarol, avarone, illimaquinone, nakijiquinone and bolinaquinone, offer promising opportunities for the development of new antitumor agents. The present review summarizes the structure and cytotoxicity of natural terpenequinones/hydroquinones and their bioactive analogues and derivatives. PMID:21339953

  3. Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

    PubMed Central

    Wirth, Marius; Niro, Giuliana; Leyerer, Kristin

    2016-01-01

    Summary Muraymycins are a promising class of antimicrobial natural products. These uridine-derived nucleoside-peptide antibiotics inhibit the bacterial membrane protein translocase I (MraY), a key enzyme in the intracellular part of peptidoglycan biosynthesis. This review describes the structures of naturally occurring muraymycins, their mode of action, synthetic access to muraymycins and their analogues, some structure–activity relationship (SAR) studies and first insights into muraymycin biosynthesis. It therefore provides an overview on the current state of research, as well as an outlook on possible future developments in this field. PMID:27340469

  4. Resistance issues with new nucleoside/nucleotide backbone options.

    PubMed

    Wainberg, Mark A; Turner, Dan

    2004-09-01

    The nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs/NtRTIs) remain an enduring feature of combination therapy. As NRTI/NtRTI options continue to expand, questions arise about how best to combine these agents to create effective dual NRTI/NtRTI backbones in antiretroviral regimens while avoiding treatment-emergent drug resistance. Clinicians must consider how NRTIs/NtRTIs such as tenofovir DF (TDF), abacavir (ABC), and emtricitabine (FTC), as well as new once-daily and coformulated NRTIs/NtRTIs, interact with older agents when combined in novel regimens and how sequencing the new NRTIs can preserve future treatment options. Resistance data from clinical trials have revealed important information on the patterns, prevalence, and effects of resistance seen among patients experiencing virologic failure. In recent years, the prevalence of some mutations such as M184V and Q151M has remained relatively constant, while the L74V mutation, the 69 insertions, and thymidine analogue mutations have decreased in prevalence. Other mutations such as K65R and Y115F, while still relatively uncommon, are increasing in prevalence. This increase may be due to the use of new treatment combinations that select for these mutations at a higher rate. Clinical trials suggest that new regimens containing TDF or ABC select for K65R and that this mutation is observed more frequently with TDF; in contrast, L74V is observed more frequently in ABC-containing regimens but is not commonly selected by TDF-containing regimens. Several lines of evidence are converging to suggest that the presence of zidovudine may decrease the risk of L74V and K65R in ABC- or TDF-containing regimens. This review summarizes the clinical implications of resistance profiles associated with new NRTI/NtRTI regimens in current use and in advanced clinical studies. PMID:15319668

  5. Hypouricemic effects of novel concentrative nucleoside transporter 2 inhibitors through suppressing intestinal absorption of purine nucleosides.

    PubMed

    Hiratochi, Masahiro; Tatani, Kazuya; Shimizu, Kazuo; Kuramochi, Yu; Kikuchi, Norihiko; Kamada, Noboru; Itoh, Fumiaki; Isaji, Masayuki

    2012-09-01

    We have developed concentrative nucleoside transporter 2 (CNT2) inhibitors as a novel pharmacological approach for improving hyperuricemia by inhibiting intestinal absorption of purines. Dietary purine nucleosides are absorbed in the small intestines by CNTs expressed in the apical membrane. In humans, the absorbed purine nucleosides are rapidly degraded to their final end product, uric acid, by xanthine oxidase. Based on the expression profile of human CNTs in digestive tract tissues, we established a working hypothesis that mainly CNT2 contributes to the intestinal absorption of purine nucleosides. In order to confirm this possibility, we developed CNT2 inhibitors and found that (2R,3R,4S,5R)-2-(6-amino-8-{[3'-(3-aminopropoxy)-biphenyl-4-ylmethyl]-amino}-9H-purin-9-yl)-5-hydroxymethyl-tetrahydrofuran-3,4-diol (KGO-2142) and 1-[3-(5-{[1-((2R,3R,4S,5R)-3,4-dihydroxy-5-hydroxymethyl-tetrahydrofuran-2-yl)-1H-benzimidazol-2-ylamino]-methyl}-2-ethoxyphenoxy)-propyl]-piperidine-4-carboxylic acid amide (KGO-2173) were inhibitory. These CNT2 inhibitors had potent inhibitory activity against inosine uptake via human CNT2, but they did not potently interfere with nucleoside uptake via human CNT1, CNT3 or equilibrative nucleoside transporters (ENTs) in vitro. After oral administration of KGO-2173 along with [(14)C]-inosine, KGO-2173 significantly decreased the urinary excretion of radioactivity at 6 and 24h in rats. Since dietary purine nucleosides are not utilized in the body and are excreted into the urine rapidly, this decrease in radioactivity in the urine represented the inhibitory activity of KGO-2173 toward the absorption of [(14)C]-inosine in the small intestines. KGO-2142 almost completely inhibited dietary RNA-induced hyperuricemia and the increase in urinary excretion of uric acid in cebus monkeys. These novel CNT2 inhibitors, KGO-2142 and KGO-2173, could be useful therapeutic options for the treatment of hyperuricemia. PMID:22709993

  6. Four new cytotoxic xanthones from Garcinia nujiangensis.

    PubMed

    Tang, Zhong-Yan; Xia, Zheng-Xiang; Qiao, Shi-Ping; Jiang, Chao; Shen, Guo-Rong; Cai, Mei-Xiang; Tang, Xiao-Yan

    2015-04-01

    Bioassay-guided fractionation of the acetone extract of the twigs of Garcinia nujiangensis resulted in the isolation of four new prenylated xanthones, nujiangexanthones C-F (1-4), and ten known related analogues. The structures of compounds 1-4 were elucidated by interpretation of their spectroscopic data. The compounds isolated were evaluated for their cytotoxic effects against three cancer cell lines, the test substances demonstrated selectivity toward the cancer cells. PMID:25727735

  7. Enantioselective Supramolecular Carriers for Nucleoside Drugs. A Thermodynamic and Kinetic Gas Phase Investigation

    NASA Astrophysics Data System (ADS)

    Fraschetti, Caterina; Filippi, Antonello; Crestoni, Maria Elisa; Villani, Claudio; Roselli, Graziella; Mortera, Stefano Levi; Speranza, Maurizio

    2012-10-01

    The enantioselective interactions between chiral tetra-amidic receptors and nucleosides have been investigated by the ESI-IT-MS and ESI-FT-ICR-MS methodologies. Configurational effects on the CID fragmentation of diastereomeric [ M H 2 •H•A] + aggregates (A = 2'-deoxycytidine dC, citarabine ( ara-C) were found to be mostly offset by isotope effect in [ S X 2 •H•A] + (X = H, D) differently from the results obtained on the analogues (A = cytidine C and gemcitabine G). This result points the involvement of two different nucleoside/tetraamide isoforms. The structural differences of the [ M H 2 •H•A] + (A = C and G) complexes vs. the [ M H 2 •H•A] + ( dC and ara-C) ones is fully confirmed by the kinetics of their uptake of the 2-aminobutane enantiomers, measured by FT-ICR mass spectrometry. Indeed, uptake of the 2-aminobutane enantiomers by [ M H n •H•A] + (n = 1,2; A = dC and ara-C) complexes is reversible, while that by [ M H n •H•A] + (n = 1,2; A = C and G) is not. The most encouraging result concerning the measured fragmentation and kinetic differences between C and ara-C, that are just epimers, indicates the possibility to subtly modulate the non-covalent drug/receptor interactions, through the electronic properties of the 2'-substituent on the nucleoside furanose ring, and furthermore on its three-dimensional position.

  8. Enantioselective supramolecular carriers for nucleoside drugs. A thermodynamic and kinetic gas phase investigation.

    PubMed

    Fraschetti, Caterina; Filippi, Antonello; Crestoni, Maria Elisa; Villani, Claudio; Roselli, Graziella; Mortera, Stefano Levi; Speranza, Maurizio

    2012-10-01

    The enantioselective interactions between chiral tetra-amidic receptors and nucleosides have been investigated by the ESI-IT-MS and ESI-FT-ICR-MS methodologies. Configurational effects on the CID fragmentation of diastereomeric [M(H)(2)•H•A](+) aggregates (A = 2'-deoxycytidine dC, citarabine (ara-C) were found to be mostly offset by isotope effect in [S(X)(2)•H•A](+) (X = H, D) differently from the results obtained on the analogues (A = cytidine C and gemcitabine G). This result points the involvement of two different nucleoside/tetraamide isoforms. The structural differences of the [M(H)(2)•H•A](+) (A = C and G) complexes vs. the [M(H)(2)•H•A](+) (dC and ara-C) ones is fully confirmed by the kinetics of their uptake of the 2-aminobutane enantiomers, measured by FT-ICR mass spectrometry. Indeed, uptake of the 2-aminobutane enantiomers by [M(H)(n)•H•A](+) (n = 1,2; A = dC and ara-C) complexes is reversible, while that by [M(H)(n)•H•A](+) (n = 1,2; A = C and G) is not. The most encouraging result concerning the measured fragmentation and kinetic differences between C and ara-C, that are just epimers, indicates the possibility to subtly modulate the non-covalent drug/receptor interactions, through the electronic properties of the 2'-substituent on the nucleoside furanose ring, and furthermore on its three-dimensional position. PMID:22864826

  9. Cellular Uptake of Decitabine by Equilibrative Nucleoside Transporters in HCT116 Cells.

    PubMed

    Ueda, Kumiko; Hosokawa, Mika; Iwakawa, Seigo

    2015-01-01

    DNA hypermethylation, an epigenetic change that silences gene expression without altering nucleotide sequences, plays a critical role in the formation and progression of colorectal cancers as well as in the acquisition of drug resistance. Decitabine (DAC), a DNA methyltransferase 1 inhibitor of nucleoside analogues, has been shown to restore gene expression silenced by hypermethylation. In the present study, the mechanisms underlying both uridine and DAC uptake were examined in the human colon cancer cell line HCT116. Real-time polymerase chain reaction analysis revealed that ENT1 mRNA was the most abundant among the nucleoside transporters examined in HCT116 cells. The ENT1 protein was detected in the membrane fraction, as determined by Western blotting. The uptake of uridine or DAC was time- and concentration-dependent, but also Na(+)-independent. The uptake of these agents was inhibited by S-(4-nitrobenzyl)-6-thioinosine (NBMPR), an inhibitor of equilibrative nucleoside transporters (ENTs), and was also decreased in cells treated with ENT1 small interfering RNA. The uptake of both uridine and DAC was inhibited by uridine, cytidine, adenosine, or inosine, while that of DAC was also inhibited by thymidine. The expression of MAGEA1 mRNA, the DNA of which was methylated in HCT116 cells, was increased by DAC treatment, and this increment was attenuated by concomitant treatment with NBMPR. The IC50 value of DAC was also increased in the presence of NBMPR. These results suggest that DAC is mainly taken up by ENT1 and that this uptake is one of the key determinants of the activity of DAC in HCT116 cells. PMID:26235575

  10. Cytotoxic diterpenoids from Jatropha curcas cv. nigroviensrugosus CY Yang Roots.

    PubMed

    Liu, JieQing; Yang, YuanFeng; Xia, JianJun; Li, XuYang; Li, ZhongRong; Zhou, Lin; Qiu, MingHua

    2015-09-01

    An investigation of phytochemicals from the roots of Jatropha curcas cv. nigroviensrugosus resulted in the isolation of twenty diterpenoids, including lathyranlactone, an unusual diterpenoid lactone possessing a 5/13/3 tricyclic skeleton, jatrocurcasenones A-E and jatrophodiones B-E, as well as 10 known analogues. All isolates were evaluated for cytotoxicity against the HL-60, SMMC-772, A-549, MCF-7 and SW480 human tumor cell lines using the MTS viability assay. Four of the known analogues showed cytotoxic activity in these cell lines, with IC50 values ranging from 2.0 to 23.0 μM. Moreover, the assessment of their cytotoxic structure-activity relationships showed the epoxy ring between C-5 and C-6 and the hydroxyl group at C-2 were the key functionalities for cytotoxicity. PMID:26209936

  11. Hybridization accompanying FRET event in labeled natural nucleoside-unnatural nucleoside containing chimeric DNA duplexes.

    PubMed

    Bag, Subhendu Sekhar; Das, Suman K; Pradhan, Manoj Kumar; Jana, Subhashis

    2016-09-01

    Förster resonance energy transfer (FRET) is a highly efficient strategy in illuminating the structures, structural changes and dynamics of DNA, proteins and other biomolecules and thus is being widely utilized in studying such phenomena, in designing molecular/biomolecular probes for monitoring the hybridization event of two single stranded DNA to form duplex, in gene detection and in many other sensory applications in chemistry, biology and material sciences. Moreover, FRET can give information about the positional status of chromophores within the associated biomolecules with much more accuracy than other methods can yield. Toward this end, we want to report here the ability of fluorescent unnatural nucleoside, triazolylphenanthrene ((TPhen)BDo) to show FRET interaction upon hybridization with fluorescently labeled natural nucleosides, (Per)U or (OxoPy)U or (Per)U, forming two stable chimeric DNA duplexes. The pairing selectivity and the thermal duplex stability of the chimeric duplexes are higher than any of the duplexes with natural nucleoside formed. The hybridization results in a Förster resonance energy transfer (FRET) from donor triazolylphenanthrene of (TPhen)BDo to acceptor oxopyrene of (OxoPy)U and/or to perylene chromophore of (Per)U, respectively, in two chimeric DNA duplexes. Therefore, we have established the FRET process in two chimeric DNA duplexes wherein a fluorescently labeled natural nucleoside ((OxoPy)U or (Per)U) paired against an unnatural nucleoside ((TPhen)BDo) without sacrificing the duplex stability and B-DNA conformation. The hybridization accompanying FRET event in these classes of interacting fluorophores is new. Moreover, there is no report of such designed system of chimeric DNA duplex. Our observed phenomenon and the design can potentially be exploited in designing more of such efficient FRET pairs for useful application in the detection and analysis of biomolecular interactions and in material science application. PMID:27498231

  12. Broad-spectrum antiviral and cytocidal activity of cyclopentenylcytosine, a carbocyclic nucleoside targeted at CTP synthetase.

    PubMed

    De Clercq, E; Murase, J; Marquez, V E

    1991-06-15

    Cyclopentenylcytosine (Ce-Cyd) is a broad-spectrum antiviral agent active against DNA viruses [herpes (cytomegalo), pox (vaccinia)], (+)RNA viruses [picorna (polio, Coxsackie, rhino), toga (Sindbis, Semliki forest), corona], (-)RNA viruses [orthomyxo (influenza), paramyxo (parainfluenza, measles), arena (Junin, Tacaribe), rhabdo (vesicular stomatitis)] and (+/-)RNA viruses (reo). Ce-Cyd is a more potent antiviral agent than its saturated counterpart, cyclopentylcytosine (carbodine, C-Cyd). Ce-Cyd also has potent cytocidal activity against a number of tumor cell lines. The putative target enzyme for both the antiviral and antitumor action of Ce-Cyd is assumed to be the CTP synthetase that converts UTP to CTP. In keeping with this hypothesis was the finding that the antiviral and cytocidal effects of Ce-Cyd are readily reversed by Cyd and, to a lesser extent, Urd, but not by other nucleosides such as dThd or dCyd. In contrast, pyrazofurin and 6-azauridine, two nucleoside analogues that are assumed to interfere with OMP decarboxylase, another enzyme involved in the biosynthesis of pyrimidine ribonucleotides, potentiate the cytocidal activity of Ce-Cyd. Ce-Cyd should be further pursued, as such and in combination with OMP decarboxylase inhibitors, for its therapeutic potential in the treatment of both viral and neoplastic diseases. PMID:1710119

  13. Parameterization of AZT-A widely used nucleoside inhibitor of HIV-1 reverse transcriptase

    NASA Astrophysics Data System (ADS)

    Carvalho, Alexandra T. P.; Fernandes, Pedro A.; Ramos, Maria J.

    Seven nucleoside reverse transcriptase (RT) inhibitors are currently used in the clinical treatment of acquired immunodeficiency syndrome (AIDS). These substrate analogues block DNA synthesis by the viral enzyme RT. However, the emergence of resistant variants of RT allied to their long-term toxicity requires the design of new and better RT inhibitors, with long-term in vivo efficacy. In this work we used density functional theory (DFT) calculations to develop a set of molecular mechanics (MM) parameters committed to the AMBER force field for one of the most used in the clinic nucleoside reverse transcriptase inhibitors (NRTIs): zidovudine (AZT). These parameters were tested by comparing the optimized geometries of AZT at both the DFT and MM levels of theory. The ability of the new parameters to reproduce the torsional energy of the azide group was also verified by scanning the surface in MM with the new parameters and comparing the results with the same potential energy surface (PES) at the DFT level. Finally, the parameters were validated through classical MD simulations of AZT in aqueous environment.

  14. The ligand binding mechanism to purine nucleoside phosphorylase elucidated via molecular dynamics and machine learning

    PubMed Central

    Decherchi, Sergio; Berteotti, Anna; Bottegoni, Giovanni; Rocchia, Walter; Cavalli, Andrea

    2015-01-01

    The study of biomolecular interactions between a drug and its biological target is of paramount importance for the design of novel bioactive compounds. In this paper, we report on the use of molecular dynamics (MD) simulations and machine learning to study the binding mechanism of a transition state analogue (DADMe–immucillin-H) to the purine nucleoside phosphorylase (PNP) enzyme. Microsecond-long MD simulations allow us to observe several binding events, following different dynamical routes and reaching diverse binding configurations. These simulations are used to estimate kinetic and thermodynamic quantities, such as kon and binding free energy, obtaining a good agreement with available experimental data. In addition, we advance a hypothesis for the slow-onset inhibition mechanism of DADMe–immucillin-H against PNP. Combining extensive MD simulations with machine learning algorithms could therefore be a fruitful approach for capturing key aspects of drug–target recognition and binding. PMID:25625196

  15. (Biological applications of nucleosides and nucleotides)

    SciTech Connect

    Srivastava, P.C.

    1990-08-20

    The traveler was invited to visit The Meditech Group, VTT Technology, Inc., Reactor Laboratory, VTT Technical Research Center of Finland (VTT), Otakaari, Espoo, Finland. The Meditech Group commands a 70 percent market share of Finland's radiopharmaceutical business and plans to expand its activities to other Scandinavian countries as well as in the Leningrad area of USSR. Meditech has plans to separate itself from Technical Research Center of Finland and its subsidiary VTT Technology, Inc., to become a private radiopharmaceutical company in the near future. As a private company, Meditech could expand its activities to encompass radiopharmaceutical research and development and may require foreign technical experts to support its research endeavors. The traveler also attended the Ninth International Round Table Conference on Nucleosides, Nucleotides, and Their Biological Applications held at the Biomedical Center, University of Uppsala, Uppsala, Sweden. The meeting focused on the chemistry and biology of RNA and DNA and their building blocks, nucleosides and nucleotides. The traveler also presented an invited paper entitled Design, Synthesis and Tumor Specificity of Azomycin Ribo- and Acyclonucleosides,'' describing his recent work at Oak Ridge National Laboratory.

  16. An improved method for the enzymatic transformation of nucleosides into 5'-monophosphates.

    PubMed

    Barai, Vladimir N; Kvach, Sergei V; Zinchenko, Anatoli I; Mikhailopulo, Igor A

    2004-12-01

    An improved method to transform nucleosides into 5'-monophosphates using nucleoside phosphotransferase from Erwinia herbicola is reported. The method is based on the shift in the equilibrium state of the reaction to the formation of desired product due to its precipitation by Zn2+. Under optimal conditions, the extent of nucleoside transformations into nucleoside-5'-monophosphates were 41-91% (mol). PMID:15672226

  17. Natural and engineered biosynthesis of nucleoside antibiotics in Actinomycetes.

    PubMed

    Chen, Wenqing; Qi, Jianzhao; Wu, Pan; Wan, Dan; Liu, Jin; Feng, Xuan; Deng, Zixin

    2016-03-01

    Nucleoside antibiotics constitute an important family of microbial natural products bearing diverse bioactivities and unusual structural features. Their biosynthetic logics are unique with involvement of complex multi-enzymatic reactions leading to the intricate molecules from simple building blocks. Understanding how nature builds this family of antibiotics in post-genomic era sets the stage for rational enhancement of their production, and also paves the way for targeted persuasion of the cell factories to make artificial designer nucleoside drugs and leads via synthetic biology approaches. In this review, we discuss the recent progress and perspectives on the natural and engineered biosynthesis of nucleoside antibiotics. PMID:26153500

  18. Antimalarial activity of prodrugs of N-branched acyclic nucleoside phosphonate inhibitors of 6-oxopurine phosphoribosyltransferases.

    PubMed

    Hocková, Dana; Janeba, Zlatko; Naesens, Lieve; Edstein, Michael D; Chavchich, Marina; Keough, Dianne T; Guddat, Luke W

    2015-09-01

    Acyclic nucleoside phosphonates (ANPs) that contain a 6-oxopurine base are good inhibitors of the human and Plasmodium falciparum 6-oxopurine phosphoribosyltransferases (PRTs), key enzymes of the purine salvage pathway. Chemical modifications, based on the crystal structures of several inhibitors in complex with the human PRTase, led to the design of a new class of inhibitors--the aza-ANPs. Because of the negative charges of the phosphonic acid moiety, their ability to cross cell membranes is, however, limited. Thus, phosphoramidate prodrugs of the aza-ANPs were prepared to improve permeability. These prodrugs arrest parasitemia with IC50 values in the micromolar range against Plasmodium falciparum-infected erythrocyte cultures (both chloroquine-sensitive and chloroquine-resistant Pf strains). The prodrugs exhibit low cytotoxicity in several human cell lines. Thus, they fulfill two essential criteria to qualify them as promising antimalarial drug leads. PMID:26275679

  19. Hepatotoxicity of nucleoside reverse transcriptase inhibitors.

    PubMed

    Montessori, Valentina; Harris, Marianne; Montaner, Julio S G

    2003-05-01

    Hepatotoxicity is an adverse effect of all available classes of antiretrovirals, including nucleoside reverse transcriptase inhibitors (NRTI). A syndrome of hepatic steatosis and lactic acidosis has been recognized as a rare, potentially fatal complication since the advent of NRTI monotherapy in the early 1990s. Today, NRTI remain the backbone of antiretroviral combination regimens, and, with the success of current treatment strategies, exposure to two or more of these agents may occur over a number of years. Hepatic steatosis and lactic acidosis are accordingly being observed more frequently, along with a more recently recognized syndrome of chronic hyperlactatemia. These as well as other adverse effects of NRTI are mediated by inhibition of human DNA polymerase gamma, resulting in mitochondrial dysfunction in the liver and other tissues. Early recognition and intervention are essential to avert serious outcomes. PMID:12800069

  20. Functional non-nucleoside adenylyl cyclase inhibitors.

    PubMed

    Lelle, Marco; Hameed, Abdul; Ackermann, Lisa-Maria; Kaloyanova, Stefka; Wagner, Manfred; Berisha, Filip; Nikolaev, Viacheslav O; Peneva, Kalina

    2015-05-01

    In this study, we describe the synthesis of novel functional non-nucleoside adenylyl cyclase inhibitors, which can be easily modified with thiol containing biomolecules such as tumour targeting structures. The linkage between inhibitor and biomolecule contains cleavable bonds to enable efficient intracellular delivery in the reductive milieu of the cytosol as well as in the acidic environment within endosomes and lysosomes. The suitability of this synthetic approach was shown by the successful bioconjugation of a poor cell-permeable inhibitor with a cell-penetrating peptide. Additionally, we have demonstrated the excellent inhibitory effect of the compounds presented here in a live-cell Förster resonance energy transfer-based assay in human embryonic kidney cells. PMID:25319071

  1. Cytotoxic dibromotyrosine-derived metabolites from the sponge Aplysina gerardogreeni.

    PubMed

    Hernández-Guerrero, Claudia J; Zubía, Eva; Ortega, María J; Carballo, J Luis

    2007-08-01

    The chemical study of the sponge Aplysina gerardogreeni collected at the Gulf of California has led to the isolation of four new dibromotyrosine-derived metabolites, aplysinones A-D, whose structures were determined by spectroscopic analysis and chemical methods. The new compounds and four semisynthetic analogues prepared in this study have shown cytotoxic activity against human tumor cell lines. PMID:17512741

  2. Cell cycle modulation by a multitargeted antifolate, LY231514, increases the cytotoxicity and antitumor activity of gemcitabine in HT29 colon carcinoma.

    PubMed

    Tonkinson, J L; Worzalla, J F; Teng, C H; Mendelsohn, L G

    1999-08-01

    The proliferation rate of HT29 colon carcinoma cells was decreased by the multitargeted antifolate (MTA), LY231514. This effect correlated with a buildup of cells near the G1-S interface after 24 h of incubation, and a synchronized progression of the population through S phase during the next 24 h. MTA treatment (0.03-3 microM) was minimally cytotoxic (20-30%) to HT29 cells after a 24-h exposure, and no dose response was observed. In contrast, the nucleoside analogue gemcitabine (GEM) was cytotoxic (IC50, 0.071 +/- 0.011 microM; IC90, 0.648 +/- 0.229 microM) after a 24-h exposure. We hypothesized that pretreatment of these cells with MTA would increase the potency of GEM by synchronizing the population for DNA synthesis. The cytotoxicity of GEM increased 2-7-fold when MTA was administered 24 h before GEM (IC50, 0.032 +/- 0.009 microM; IC90, 0.094 +/- 0.019 microM). In addition, an increase in cell kill for the combination compared with GEM alone (IC99, 12 microM for GEM alone; IC99, 0.331 microM for combination) was observed. No increase in potency or cell kill was observed when the two compounds were added simultaneously. MTA pretreatment also potentiated the cytotoxicity of a 1-h exposure to GEM. These cell-based observations were extended to evaluate the schedule-dependent interaction of these two agents in vivo using a nude mouse HT29 xenograft tumor model. At the doses tested, MTA alone (100 mg/kg) had a marginal effect on tumor growth delay, whereas GEM (80 mg/kg) produced a statistically significant tumor growth delay. In combination, the increase in tumor growth delay was greatest when MTA was administered before GEM, compared with simultaneous drug administration or the reverse sequence, e.g., GEM followed by MTA. The effect of sequential administration of MTA followed by GEM was greater than additive, indicating synergistic interaction of these agents. Thus, in vitro, MTA induced cell cycle effects on HT29 cells that resulted in potentiation of the

  3. 8-Modified-2′-Deoxyadenosine Analogues Induce Delayed Polymerization Arrest during HIV-1 Reverse Transcription

    PubMed Central

    Sleiman, Marwan; Smyth, Redmond; Ben Gaied, Nouha; Barhoum, Patrick; Laumond, Géraldine; Bec, Guillaume; Götte, Matthias; Mak, Johnson; Aubertin, Anne-Marie; Burger, Alain; Marquet, Roland

    2011-01-01

    The occurrence of resistant viruses to any of the anti-HIV-1 compounds used in the current therapies against AIDS underlies the urge for the development of new drug targets and/or new drugs acting through novel mechanisms. While all anti-HIV-1 nucleoside analogues in clinical use and in clinical trials rely on ribose modifications for activity, we designed nucleosides with a natural deoxyribose moiety and modifications of position 8 of the adenine base. Such modifications might induce a steric clash with helix αH in the thumb domain of the p66 subunit of HIV-1 RT at a distance from the catalytic site, causing delayed chain termination. Eleven new 2′-deoxyadenosine analogues modified on position 8 of the purine base were synthesized and tested in vitro and in cell-based assays. In this paper we demonstrate for the first time that chemical modifications on position 8 of 2′-deoxyadenosine induce delayed chain termination in vitro, and also inhibit DNA synthesis when incorporated in a DNA template strand. Furthermore, one of them had moderate anti-HIV-1 activity in cell-culture. Our results constitute a proof of concept indicating that modification on the base moiety of nucleosides can induce delayed polymerization arrest and inhibit HIV-1 replication. PMID:22087320

  4. Crystal structure of a concentrative nucleoside transporter from Vibrio cholerae at 2.4;#8201;Å

    SciTech Connect

    Johnson, Zachary Lee; Cheong, Cheom-Gil; Lee, Seok-Yong

    2012-07-11

    Nucleosides are required for DNA and RNA synthesis, and the nucleoside adenosine has a function in a variety of signalling processes. Transport of nucleosides across cell membranes provides the major source of nucleosides in many cell types and is also responsible for the termination of adenosine signalling. As a result of their hydrophilic nature, nucleosides require a specialized class of integral membrane proteins, known as nucleoside transporters (NTs), for specific transport across cell membranes. In addition to nucleosides, NTs are important determinants for the transport of nucleoside-derived drugs across cell membranes. A wide range of nucleoside-derived drugs, including anticancer drugs (such as Ara-C and gemcitabine) and antiviral drugs (such as zidovudine and ribavirin), have been shown to depend, at least in part, on NTs for transport across cell membranes. Concentrative nucleoside transporters, members of the solute carrier transporter superfamily SLC28, use an ion gradient in the active transport of both nucleosides and nucleoside-derived drugs against their chemical gradients. The structural basis for selective ion-coupled nucleoside transport by concentrative nucleoside transporters is unknown. Here we present the crystal structure of a concentrative nucleoside transporter from Vibrio cholerae in complex with uridine at 2.4 {angstrom}. Our functional data show that, like its human orthologues, the transporter uses a sodium-ion gradient for nucleoside transport. The structure reveals the overall architecture of this class of transporter, unravels the molecular determinants for nucleoside and sodium binding, and provides a framework for understanding the mechanism of nucleoside and nucleoside drug transport across cell membranes.

  5. Asymmetric Hydrogenation of α-Purine Nucleobase-Substituted Acrylates with Rhodium Diphosphine Complexes: Access to Tenofovir Analogues.

    PubMed

    Sun, Huan-Li; Chen, Fei; Xie, Ming-Sheng; Guo, Hai-Ming; Qu, Gui-Rong; He, Yan-Mei; Fan, Qing-Hua

    2016-05-01

    The first asymmetric hydrogenation of α-purine nucleobase-substituted α,β-unsaturated esters, catalyzed by a chiral rhodium (R)-Synphos catalyst, has been developed. A wide range of mono- and disubstituted acrylates were successfully hydrogenated under very mild conditions in high yields with good to excellent enantioselectivities (up to 99% ee). This method provides a convenient approach to the synthesis of a new kind of optically pure acyclic nucleoside and Tenofovir analogues. PMID:27112983

  6. Base-Modified Nucleosides as Chemotherapeutic Agents: Past and Future.

    PubMed

    Burke, Matthew P; Borland, Kayla M; Litosh, Vladislav A

    2016-01-01

    Nucleoside and nucleobase antimetabolites have substantially impacted treatment of cancer and infections. Their close resemblance to natural analogs gives them the power to interfere with a variety of intracellular targets, which on one hand gives them high potency, but on the other hand incurs severe side effects, especially of the chemotherapeutics used against malignancies. Therefore, the development of novel nucleoside analogs with widened therapeutic windows represents an attractive target to synthetic organic and medicinal chemists. This review discusses the current antimetabolite drugs: 5- fluorouracil, 6-mercaptopurine, 6-thioguanine, Cladribine, Vidaza, Decitabine, Emtricitabine, Abacavir, Sorivudine, Clofarabine, Fludarabine, and Nelarabine; gives insight into the nucleoside drug candidates that are being developed; and outlines the approaches to nucleobase modifications that may help discover novel bioactive nucleoside analogs with the mechanism of action focused on termination of DNA synthesis, which is expected to diminish the off-target toxicity in non-proliferating human cells. PMID:26369814

  7. Nucleoside transporter expression and function in cultured mouse astrocytes.

    PubMed

    Peng, Liang; Huang, Rong; Yu, Albert C H; Fung, King Y; Rathbone, Michel P; Hertz, Leif

    2005-10-01

    Uptake of purine and pyrimidine nucleosides in astrocytes is important for several reasons: (1) uptake of nucleosides contributes to nucleic acid synthesis; (2) astrocytes synthesize AMP, ADP, and ATP from adenosine and GTP from guanosine; and (3) adenosine and guanosine function as neuromodulators, whose effects are partly terminated by cellular uptake. It has previously been shown that adenosine is rapidly accumulated by active uptake in astrocytes (Hertz and Matz, Neurochem Res 14:755-760, 1989), but the ratio between active uptake and metabolism-driven uptake of adenosine is unknown, as are uptake characteristics for guanosine. The present study therefore aims at providing detailed information of nucleoside transport and transporters in primary cultures of mouse astrocytes. Reverse transcription-polymerase chain reaction identified the two equilibrative nucleoside transporters, ENT1 and ENT2, together with the concentrative nucleoside transporter CNT2, whereas CNT3 was absent, and CNT1 expression could not be investigated. Uptake studies of tritiated thymidine, formycin B, guanosine, and adenosine (3-s uptakes at 1-4 degrees C to study diffusional uptake and 1-60-min uptakes at 37 degrees C to study concentrative uptake) demonstrated a fast diffusional uptake of all four nucleosides, a small, Na(+)-independent and probably metabolism-driven uptake of thymidine (consistent with DNA synthesis), larger metabolism-driven uptakes of guanosine (consistent with synthesis of DNA, RNA, and GTP) and especially of adenosine (consistent with rapid nucleotide synthesis), and Na(+)-dependent uptakes of adenosine (consistent with its concentrative uptake) and guanosine, rendering neuromodulator uptake independent of nucleoside metabolism. Astrocytes are accordingly well suited for both intense nucleoside metabolism and metabolism-independent uptake to terminate neuromodulator effects of adenosine and guanosine. PMID:15892125

  8. Synthesis and Evaluation of 2'-Deoxy-2'-Spirodiflurocyclopropyl Nucleoside Analogs.

    PubMed

    Liu, Xiao; Xia, Xueliang; Sun, Chenghai; Lin, Cai; Zhou, Yiqian; Hussain, Muzammal; Tang, Fei; Liu, Lu; Li, Xue; Zhang, Jiancun

    2016-09-01

    The preparation of 2'-deoxy-2'-siprodifluorocyclopropany-lnucleoside analogs has been achieved from α-d-glucose in several steps. The key step in the synthesis was the introduction of the difluorocyclopropane through a difluorocarbene type reaction at the 2'-position. Then, a series of novel 2'-deoxy-2'-spirodifluorocyclopropanyl nucleoside analogs were synthesized using the Vorbrüggen method. All the synthesized nucleosides were characterized and subsequently evaluated against hepatitis C and influenza A virus strains in vitro. PMID:27556785

  9. Distribution of nucleosides in populations of Cordyceps cicadae.

    PubMed

    Zeng, Wen-Bo; Yu, Hong; Ge, Feng; Yang, Jun-Yuan; Chen, Zi-Hong; Wang, Yuan-Bing; Dai, Yong-Dong; Adams, Alison

    2014-01-01

    A rapid HPLC method had been developed and used for the simultaneous determination of 10 nucleosides (uracil, uridine, 2'-deoxyuridine, inosine, guanosine, thymidine, adenine, adenosine, 2'-deoxyadenosine and cordycepin) in 10 populations of Cordyceps cicadae, in order to compare four populations of Ophicordyceps sinensis and one population of Cordyceps militaris. Statistical analysis system (SAS) 8.1 was used to analyze the nucleoside data. The pattern of nucleoside distribution was analyzed in the sampled populations of C. cicadae, O. sinensis and C. militaris, using descriptive statistical analysis, nested analysis and Q cluster analysis. The total amount of the 10 nucleosides in coremium was 1,463.89-5,678.21 µg/g in 10 populations of C. cicadae, 1,369.80-3,941.64 µg/g in sclerotium. The average contents of the 10 analytes were 4,392.37 µg/g and 3,016.06 µg/g in coremium and sclerotium, respectively. The coefficient of variation (CV) of nucleosides ranged from 8.36% to 112.36% in coremium of C. cicadae, and from 10.77% to 155.87% in sclerotium of C. cicadae. The CV of the nucleosides was wide within C. cicadae populations. The nested variation analysis by the nine nucleosides' distribution indicated that about 42.29% of the nucleoside variability in coremium was attributable to the differentiation among populations, and the remaining 57.71% resided in the populations. It was also shown that about 28.94% of the variation in sclerotium was expressed between populations, while most of the variation (71.06%) corresponded to the populations. PMID:24830714

  10. Anopheles gambiae Purine Nucleoside Phosphorylase: Catalysis, Structure, and Inhibition

    SciTech Connect

    Taylor,E.; Rinaldo-Matthis, A.; Li, L.; Ghanem, M.; Hazleton, K.; Cassera, M.; Almo, S.; Schramm, V.

    2007-01-01

    The purine salvage pathway of Anopheles gambiae, a mosquito that transmits malaria, has been identified in genome searches on the basis of sequence homology with characterized enzymes. Purine nucleoside phosphorylase (PNP) is a target for the development of therapeutic agents in humans and purine auxotrophs, including malarial parasites. The PNP from Anopheles gambiae (AgPNP) was expressed in Escherichia coli and compared to the PNPs from Homo sapiens (HsPNP) and Plasmodium falciparum (PfPNP). AgPNP has kcat values of 54 and 41 s-1 for 2'-deoxyinosine and inosine, its preferred substrates, and 1.0 s-1 for guanosine. However, the chemical step is fast for AgPNP at 226 s-1 for guanosine in pre-steady-state studies. 5'-Deaza-1'-aza-2'-deoxy-1'-(9-methylene)-Immucillin-H (DADMe-ImmH) is a transition-state mimic for a 2'-deoxyinosine ribocation with a fully dissociated N-ribosidic bond and is a slow-onset, tight-binding inhibitor with a dissociation constant of 3.5 pM. This is the tightest-binding inhibitor known for any PNP, with a remarkable Km/Ki* of 5.4 x 107, and is consistent with enzymatic transition state predictions of enhanced transition-state analogue binding in enzymes with enhanced catalytic efficiency. Deoxyguanosine is a weaker substrate than deoxyinosine, and DADMe-Immucillin-G is less tightly bound than DADMe-ImmH, with a dissociation constant of 23 pM for AgPNP as compared to 7 pM for HsPNP. The crystal structure of AgPNP was determined in complex with DADMe-ImmH and phosphate to a resolution of 2.2 Angstroms to reveal the differences in substrate and inhibitor specificity. The distance from the N1' cation to the phosphate O4 anion is shorter in the AgPNP{center_dot}DADMe-ImmH{center_dot}PO4 complex than in HsPNP{center_dot}DADMe-ImmH{center_dot}SO4, offering one explanation for the stronger inhibitory effect of DADMe-ImmH for AgPNP.

  11. Bicyclic and Tricyclic "Expanded" Nucleobase Analogues of Sofosbuvir: New Scaffolds for Hepatitis C Therapies.

    PubMed

    Chen, Zhe; Jochmans, Dirk; Ku, Therese; Paeshuyse, Jan; Neyts, Johan; Seley-Radtke, Katherine L

    2015-08-14

    Given the impressive success of Gilead's Sofosbuvir, many laboratories, including ours, have explored the unique 2'-sugar modification (2'-Me, 2'-F) of nucleoside analogues in the hopes of exploiting the biological activity that this unique modification has imparted to the nucleoside scaffold. In that regard, we have combined our tricyclic "expanded" purine base motif with the 2'-Me, 2'-F sugar modification. Although the synthesis of these complex molecules proved to be nontrivial, with the best results coming from a linear approach, the overall strategy resulted in highly promising biological results for several of the target compounds, including their corresponding McGuigan ProTides. Modest activity against HCV was observed with inhibitory concentrations of as low as 20 μM. PMID:27624884

  12. Hamamelitannin Analogues that Modulate Quorum Sensing as Potentiators of Antibiotics against Staphylococcus aureus.

    PubMed

    Vermote, Arno; Brackman, Gilles; Risseeuw, Martijn D P; Vanhoutte, Bieke; Cos, Paul; Van Hecke, Kristof; Breyne, Koen; Meyer, Evelyne; Coenye, Tom; Van Calenbergh, Serge

    2016-05-23

    The modulation of bacterial communication to potentiate the effect of existing antimicrobial drugs is a promising alternative to the development of novel antibiotics. In the present study, we synthesized 58 analogues of hamamelitannin (HAM), a quorum sensing inhibitor and antimicrobial potentiator. These efforts resulted in the identification of an analogue that increases the susceptibility of Staphylococcus aureus towards antibiotics in vitro, in Caenorhabditis elegans, and in a mouse mammary gland infection model, without showing cytotoxicity. PMID:27095479

  13. Total synthesis and biological evaluation of tubulysin U, tubulysin V, and their analogues.

    PubMed

    Balasubramanian, Ranganathan; Raghavan, Bhooma; Begaye, Adrian; Sackett, Dan L; Fecik, Robert A

    2009-01-22

    A stereoselective total synthesis of the cytotoxic natural products tubulysin U, tubulysin V, and its unnatural epimer epi-tubulysin V, is reported. Simplified analogues containing N,N-dimethyl-D-alanine as a replacement for the N-terminal N-Me-pipecolinic acid residue of the tubulysins are also disclosed. Biological evaluation of these natural products and analogues provided key information with regard to structural and stereochemical requirements for antiproliferative activity and tubulin polymerization inhibition. PMID:19102699

  14. All-trans-retinoic Acid Promotes Trafficking of Human Concentrative Nucleoside Transporter-3 (hCNT3) to the Plasma Membrane by a TGF-β1-mediated Mechanism*

    PubMed Central

    Fernández-Calotti, Paula; Pastor-Anglada, Marçal

    2010-01-01

    Human concentrative nucleoside transporter-3 (hCNT3) is a sodium-coupled nucleoside transporter that exhibits high affinity and broad substrate selectivity, making it the most suitable candidate for mediating the uptake and cytotoxic action of most nucleoside-derived drugs. The drug of this class most commonly used in the treatment of chronic lymphocytic leukemia (CLL) is the pro-apoptotic nucleoside analog fludarabine (Flu), which enters CLL cells primarily through human equilibrative nucleoside transporters (hENTs). Although CLL cells lack hCNT3 activity, they do express this transporter protein, which is located mostly in the cytosol. The aim of our study was to identify agents and mechanisms capable of promoting hCNT3 trafficking to the plasma membrane. Here, we report that all-trans-retinoic acid (ATRA), currently used in the treatment of acute promyelocytic leukemia (APL), increases hCNT3-related activity through a mechanism that involves trafficking of pre-existing hCNT3 proteins to the plasma membrane. This effect is mediated by the autocrine action of transforming growth factor (TGF)-β1, which is transcriptionally activated by ATRA in a p38-dependent manner. TGF-β1 acts through activation of ERK1/2 and the small GTPase RhoA to promote plasma membrane trafficking of the hCNT3 protein. PMID:20172853

  15. Functional characterization of nucleoside transporter gene replacements in Leishmania donovani.

    PubMed

    Liu, Wei; Boitz, Jan M; Galazka, Jon; Arendt, Cassandra S; Carter, Nicola S; Ullman, Buddy

    2006-12-01

    Leishmania donovani express two nucleoside transporters of non-overlapping ligand selectivity. To evaluate the physiological role of nucleoside transporters in L. donovani, homozygous null mutants of the genes encoding the LdNT1 adenosine-pyrimidine nucleoside transporter and the LdNT2 inosine-guanosine transporter were created singly and in combination by single targeted gene replacement followed by selection for loss-of-heterozygosity. The mutant alleles were verified by Southern blotting, and the effects of gene replacement on transport phenotype were evaluated by rapid sampling transport measurements and by drug resistance profiles. The Deltaldnt1, Deltaldnt2, and Deltaldnt1/Deltaldnt2 mutants were all capable of proliferation in defined culture medium supplemented with any of a spectrum of purine nucleobases or nucleosides, except that a Deltaldnt2 lesion conferred an inability to efficiently salvage exogenous xanthosine, a newly discovered ligand of LdNT2. Each of the three knockout strains was viable as promastigotes and axenic amastigotes and capable of maintaining an infection in J774 and bone marrow-derived murine macrophages. These genetic studies demonstrate: (1) that L. donovani promastigotes, axenic amastigotes, and tissue amastigotes are viable in the absence of nucleoside transport; (2) that nucleoside transporters are not essential for sustaining an infection in mammalian host cells; (3) that the phagolysosome of macrophages is likely to contain purines that are not LdNT1 or LdNT2 ligands, i.e., nucleobases. Furthermore, the Deltaldnt1, Deltaldnt2, and Deltaldnt1/Deltaldnt2 knockouts offer a unique genetically defined null background for the biochemical and genetic characterization of nucleoside transporter genes and cDNAs from phylogenetically diverse species and of genetically manipulated LdNT1 and LdNT2 constructs. PMID:17050001

  16. Tetrahydrofuran amino acid-containing gramicidin S analogues with improved biological profiles.

    PubMed

    Pal, Sudip; Singh, Gajendra; Singh, Shyam; Tripathi, Jitendra Kumar; Ghosh, Jimut Kanti; Sinha, Sudhir; Ampapathi, Ravi Sankar; Chakraborty, Tushar Kanti

    2015-06-28

    Gramicidin S (GS) is a cyclic cationic antimicrobial peptide (CAP) with a wide spectrum of antibiotic activities whose usage has been limited to topical applications owing to its cytotoxic side effects. We have synthesized tetrahydrofuran amino acid (Taa)-containing GS analogues, and we have carried out conformational analysis and explored their structure activity relationships by evaluating their antitubercular, antibacterial and cytotoxic properties. Two of these analogues showed impressive as well as selective activity against Mycobacterium tuberculosis (MTB) without toxicity towards mammalian Vero cells or human RBCs, and are promising as potential leads. PMID:26008215

  17. Synthesis, analysis and biological evaluation of novel indolquinonecryptolepine analogues as potential anti-tumour agents.

    PubMed

    Le Gresley, A; Gudivaka, V; Carrington, S; Sinclair, A; Brown, J E

    2016-03-21

    A small library of cryptolepine analogues were synthesised incorporating halogens and/or nitrogen containing side chains to optimise their interaction with the sugar-phosphate backbone of DNA to give improved binding, interfering with topoisomerase II hence enhancing cytotoxicity. Cell viability, DNA binding and Topoisomerase II inhibition is discussed for these compounds. Fluorescence microscopy was used to investigate the uptake of the synthesised cryptolepines into the nucleus. We report the synthesis and anti-cancer biological evaluation of nine novel cryptolepine analogues, which have greater cytotoxicity than the parent compound and are important lead compounds in the development of novel potent and selective indoloquinone anti-neoplastic agents. PMID:26893255

  18. Synthesis of apoptotic chalcone analogues in HepG2 human hepatocellular carcinoma cells.

    PubMed

    Park, Cheon-Soo; Ahn, Yongchel; Lee, Dahae; Moon, Sung Won; Kim, Ki Hyun; Yamabe, Noriko; Hwang, Gwi Seo; Jang, Hyuk Jai; Lee, Heesu; Kang, Ki Sung; Lee, Jae Wook

    2015-12-15

    Eight chalcone analogues were prepared and evaluated for their cytotoxic effects in human hepatoma HepG2 cells. Compound 5 had a potent cytotoxic effect. The percentage of apoptotic cells was significantly higher in compound 5-treated cells than in control cells. Exposure to compound 5 for 24h induced cleavage of caspase-8 and -3, and poly (ADP-ribose) polymerase (PARP). Our findings suggest that compound 5 is the active chalcone analogue that contributes to cell death in HepG2 cells via the extrinsic apoptotic pathway. PMID:26564263

  19. Aspartame and Its Analogues

    NASA Astrophysics Data System (ADS)

    Pavlova, L. A.; Komarova, T. V.; Davidovich, Yurii A.; Rogozhin, S. V.

    1981-04-01

    The results of studies on the biochemistry of the sweet taste are briefly reviewed. The methods of synthesis of "aspartame" — a sweet dipeptide — are considered, its structural analogues are described, and quantitative estimates are made of the degree of sweetness relative to sucrose. Attention is concentrated mainly on problems of the relation between the structure of the substance and its taste in the series of aspartyl derivatives. The bibliography includes 118 references.

  20. Nucleoside transporter expression and adenosine uptake in the rat cochlea.

    PubMed

    Khan, Abdul F; Thorne, Peter R; Muñoz, David J B; Wang, Carol J H; Housley, Gary D; Vlajkovic, Srdjan M

    2007-02-12

    Even though extracellular adenosine plays multiple roles in the cochlea, the mechanisms that control extracellular adenosine concentrations in this organ are unclear. This study investigated the expression of nucleoside transporters and adenosine uptake in the rat cochlea. Reverse transcription-polymerase chain reaction revealed the expression of mRNA transcripts for two equilibrative (ENT1 and ENT2) and two concentrative (CNT1 and CNT2) nucleoside transporters. Exogenous adenosine perfused through the cochlear perilymphatic compartment was taken up by cells lining the compartment. Adenosine uptake was sensitive to changes in extracellular Na concentrations and inhibited by nitrobenzylthioinosine (an adenosine uptake blocker). The study suggests that the bi-directional nucleoside transport supports the uptake and recycling of purines and regulates the activation of adenosine receptors by altering adenosine concentrations in cochlear fluid spaces. PMID:17314663

  1. Brain transfer RNA. II. Analysis of modified nucleosides

    SciTech Connect

    Chaudhary, K.D.; Carrier-Malhotra, L.; Murthy, M.R.

    1982-01-01

    Transfer RNAs were isolated from rat and calf brains and their nucleosides were analysed by tritium derivative technique. Qualitative changes in the minor nucleoside components were compared on the fluorograms which showed differences in the intensities of spots. Cerebellar and cortical tRNAs were also compared, but revealed no significant quantitative differences in their methylated constituants despite 60% higher methyltransferase activity observed in cerebellum compared to cerebral cortex. An overall similarity was noticed between the relative proportions of the major and minor nucleosides of tRNAs derived from rat or calf brain, expressed as mol%. Brain tRNA was also analysed by two-dimensional polyacrylamide gel electrophoresis which showed qualitative and quantitative changes during postnatal development.

  2. Supramolecular gels made from nucleobase, nucleoside and nucleotide analogs.

    PubMed

    Peters, Gretchen Marie; Davis, Jeffery T

    2016-06-01

    Supramolecular or molecular gels are attractive for various applications, including diagnostics, tissue scaffolding and targeted drug release. Gelators derived from natural products are of particular interest for biomedical purposes, as they are generally biocompatible and stimuli-responsive. The building blocks of nucleic acids (i.e. nucleobases, nucleosides, and nucleotides) are desirable candidates for supramolecular gelation as they readily engage in reversible, noncovalent interactions. In this review, we describe a number of organo- and hydrogels formed through the assembly of nucleosides, nucleotides, and their derivatives. While natural nucleosides and nucleotides generally require derivatization to induce gelation, guanosine and its corresponding nucleotides are well known gelators. This unique gelating ability is due to propensity of the guanine nucleobase to self-associate into stable higher-order assemblies, such as G-ribbons, G4-quartets, and G-quadruplexes. PMID:27146863

  3. Chemoselective N-Deacetylation of Protected Nucleosides and Nucleotides Promoted by Schwartz's Reagent

    PubMed Central

    Ferrari, Valentina; Serpi, Michaela; McGuigan, Christopher; Pertusati, Fabrizio

    2015-01-01

    Protection and deprotection strategies involving the N-acetyl group are widely utilized in nucleoside and nucleotide chemistry. Herein, we present a mild and selective N-deacetylation methodology, applicable to purine and pyrimidine nucleosides, by means of Schwartz's reagent, compatible with most of the common protecting groups used in nucleoside chemistry. PMID:26492555

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

    PubMed

    Krstulja, Aleksandra; De Schutter, Coralie; Favetta, Patrick; Manesiotis, Panagiotis; Agrofoglio, Luigi A

    2014-10-24

    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. PMID:25218630

  5. Design, Synthesis, and Evaluation of Anti-HBV Activity of Hybrid Molecules of Entecavir and Adefovir: Exomethylene Acycloguanine Nucleosides and Their Monophosphate Derivatives.

    PubMed

    Imoto, Shuhei; Kohgo, Satoru; Tokuda, Ryoh; Kumamoto, Hiroki; Aoki, Manabu; Amano, Masayuki; Kuwata-Higashi, Nobuyo; Mitsuya, Hiroaki; Haraguchi, Kazuhiro

    2015-01-01

    Exomethylene acycloguanine nucleosides 4, 6 and its monophosphate derivatives 5, 7, and 8 have been synthesized. Mitsunobu-type coupling of 2-N-acetyl-6-O-diphenylcarbamoylguanine (11) with primary alcohols proceeded regioselectively to furnish the desired N(9)-substituted products in moderate yield. Evaluation of 4-8 for anti-HBV activity in HepG2 cells revealed that the phosphonate derivative 8 was found to exhibit moderated activity (EC50 value of 0.29 μM), but cytotoxicity (CC50 value of 39 μM) against the host cells was also observed. PMID:26167667

  6. New Cytotoxic 24-Homoscalarane Sesterterpenoids from the Sponge Ircinia felix

    PubMed Central

    Lai, Ya-Yuan; Chen, Li-Chai; Wu, Chug-Fung; Lu, Mei-Chin; Wen, Zhi-Hong; Wu, Tung-Ying; Fang, Lee-Shing; Wang, Li-Hsueh; Wu, Yang-Chang; Sung, Ping-Jyun

    2015-01-01

    Two new 24-homoscalarane sesterterpenoids, felixins F (1) and G (2), were isolated from the sponge Ircinia felix. The structures of new homoscalaranes 1 and 2 were elucidated by extensive spectroscopic methods, particularly with one-dimensional (1D) and two-dimensional (2D) NMR, and, by comparison, the spectral data with those of known analogues. The cytotoxicity of 1 and 2 against the proliferation of a limited panel of tumor cell lines was evaluated and 1 was found to show cytotoxicity toward the leukemia K562, MOLT-4, and SUP-T1 cells (IC50 ≤ 5.0 μM). PMID:26378524

  7. New Cytotoxic 24-Homoscalarane Sesterterpenoids from the Sponge Ircinia felix.

    PubMed

    Lai, Ya-Yuan; Chen, Li-Chai; Wu, Chug-Fung; Lu, Mei-Chin; Wen, Zhi-Hong; Wu, Tung-Ying; Fang, Lee-Shing; Wang, Li-Hsueh; Wu, Yang-Chang; Sung, Ping-Jyun

    2015-01-01

    Two new 24-homoscalarane sesterterpenoids, felixins F (1) and G (2), were isolated from the sponge Ircinia felix. The structures of new homoscalaranes 1 and 2 were elucidated by extensive spectroscopic methods, particularly with one-dimensional (1D) and two-dimensional (2D) NMR, and, by comparison, the spectral data with those of known analogues. The cytotoxicity of 1 and 2 against the proliferation of a limited panel of tumor cell lines was evaluated and 1 was found to show cytotoxicity toward the leukemia K562, MOLT-4, and SUP-T1 cells (IC50 ≤ 5.0 μM). PMID:26378524

  8. Inhibition of nucleoside diphosphate kinase in rat liver mitochondria by added 3'-azido-3'-deoxythymidine.

    PubMed

    Valenti, D; Barile, M; Quagliariello, E; Passarella, S

    1999-02-12

    The effect of 3'-azido-3'-deoxythymidine on nucleoside diphosphate kinase of isolated rat liver mitochondria has been studied. This is done by monitoring the increase in the rate of oxygen uptake by nucleoside diphosphate (TDP, UDP, CDP or GDP) addition to mitochondria in state 4. It is shown that 3'-azido-3'-deoxythymidine inhibits the mitochondrial nucleoside diphosphate kinase in a competitive manner, with a Ki value of about 10 microM as measured for each tested nucleoside diphosphate. It is also shown that high concentrations of GDP prevent 3'-azido-3'-deoxythymidine inhibition of the nucleoside diphosphate kinase. PMID:10050777

  9. Structural Analogues of Selfotel.

    PubMed

    Dziuganowska, Zofia A; Ślepokura, Katarzyna; Volle, Jean-Noël; Virieux, David; Pirat, Jean-Luc; Kafarski, Paweł

    2016-06-17

    A small library of phosphonopiperidylcarboxylic acids, analogues of NMDA antagonist selfotel (CGS 19755), was synthesized. First, the series of aromatic esters was obtained via a palladium-catalyzed cross-coupling reaction (Hirao coupling) of dialkyl phosphites with bromopyridinecarboxylates, followed by their hydrolysis. Then, hydrogenation of the resulting phosphonopyridylcarboxylic acids over PtO2 yielded the desired phosphonopiperidylcarboxylic acids. NMR studies indicated that the hydrogenation reaction proceeds predominantly by cis addition. Several compounds were obtained as monocrystal structures. Preliminary biological studies performed on cultures of neurons suggest that the obtained compounds possess promising activity toward NMDA receptors. PMID:27187758

  10. A Transition State Analogue for an RNA-Editing Reaction

    PubMed Central

    Haudenschild, Brittany L.; Maydanovych, Olena; Véliz, Eduardo A.; Macbeth, Mark R.; Bass, Brenda L.; Beal, Peter A.

    2007-01-01

    Deamination at C6 of adenosine in RNA catalyzed by the ADAR enzymes generates inosine at the corresponding position. Because inosine is decoded as guanosine during translation, this modification can lead to codon changes in messenger RNA. Hydration of 8-azanebularine across the C6–N1 double bond generates an excellent mimic of the transition state proposed for the hydrolytic deamination reaction catalyzed by ADARs. Here, we report the synthesis of a phosphoramidite of 8-azanebularine and its use in the preparation of RNAs mimicking the secondary structure found at a known editing site in the glutamate receptor B subunit pre-mRNA. The binding properties of analogue-containing RNAs indicate that a tight binding ligand for an ADAR can be generated by incorporation of 8-azanebularine. The observed high-affinity binding is dependent on a functional active site, the presence of one, but not the other, of ADAR2’s two double-stranded RNA-binding motifs (dsRBMs), and the correct placement of the nucleoside analogue into the sequence/structural context of a known editing site. These results advance our understanding of substrate recognition during ADAR-catalyzed RNA editing and are important for structural studies of ADAR· RNA complexes. PMID:15355102

  11. The GABA transaminase, ABAT, is essential for mitochondrial nucleoside metabolism

    PubMed Central

    Besse, Arnaud; Wu, Ping; Bruni, Francesco; Donti, Taraka; Graham, Brett H.; Craigen, William J.; McFarland, Robert; Moretti, Paolo; Lalani, Seema; Scott, Kenneth L.; Taylor, Robert W.; Bonnen, Penelope E.

    2015-01-01

    Summary ABAT is a key enzyme responsible for catabolism of principal inhibitory neurotransmitter gamma-aminobutyric acid (GABA). We report an essential role for ABAT in a seemingly unrelated pathway, mitochondrial nucleoside salvage, and demonstrate that mutations in this enzyme cause an autosomal recessive neurometabolic disorder and mtDNA depletion syndrome (MDS). We describe a family with encephalomyopathic MDS caused by a homozygous missense mutation in ABAT that results in elevated GABA in subjects’ brains as well as decreased mtDNA levels in subjects’ fibroblasts. Nucleoside rescue and co-IP experiments pinpoint that ABAT functions in the mitochondrial nucleoside salvage pathway to facilitate conversion of dNDPs to dNTPs. Pharmacological inhibition of ABAT through the irreversible inhibitor Vigabatrin caused depletion of mtDNA in photoreceptor cells that was prevented through addition of dNTPs in cell culture media. This work reveals ABAT as a connection between GABA metabolism and nucleoside metabolism and defines a neurometabolic disorder that includes MDS. PMID:25738457

  12. Macrophages require different nucleoside transport systems for proliferation and activation.

    PubMed

    Soler, C; García-Manteiga, J; Valdés, R; Xaus, J; Comalada, M; Casado, F J; Pastor-Anglada, M; Celada, A; Felipe, A

    2001-09-01

    To evaluate the mechanisms involved in macrophage proliferation and activation, we studied the regulation of the nucleoside transport systems. In murine bone marrow-derived macrophages, the nucleosides required for DNA and RNA synthesis are recruited from the extracellular medium. M-CSF induced macrophage proliferation and DNA and RNA synthesis, whereas interferon gamma (IFN-gamma) led to activation, blocked proliferation, and induced only RNA synthesis. Macrophages express at least the concentrative systems N1 and N2 (CNT2 and CNT1 genes, respectively) and the equilibrative systems es and ei (ENT1 and ENT2 genes, respectively). Incubation with M-CSF only up-regulated the equilibrative system es. Inhibition of this transport system blocked M-CSF-dependent proliferation. Treatment with IFN-gamma only induced the concentrative N1 and N2 systems. IFN-gamma also down-regulated the increased expression of the es equilibrative system induced by M-CSF. Thus, macrophage proliferation and activation require selective regulation of nucleoside transporters and may respond to specific requirements for DNA and RNA synthesis. This report also shows that the nucleoside transporters are critical for macrophage proliferation and activation. PMID:11532978

  13. Arabidopsis thaliana nucleosidase mutants provide new insights into nucleoside degradation

    PubMed Central

    Riegler, Heike; Geserick, Claudia; Zrenner, Rita

    2011-01-01

    A central step in nucleoside and nucleobase salvage pathways is the hydrolysis of nucleosides to their respective nucleobases. In plants this is solely accomplished by nucleosidases (EC 3.2.2.x). To elucidate the importance of nucleosidases for nucleoside degradation, general metabolism, and plant growth, thorough phenotypic and biochemical analyses were performed using Arabidopsis thaliana T-DNA insertion mutants lacking expression of the previously identified genes annotated as uridine ribohydrolases (URH1 and URH2). Comprehensive functional analyses of single and double mutants demonstrated that both isoforms are unimportant for seedling establishment and plant growth, while one participates in uridine degradation. Rather unexpectedly, nucleoside and nucleotide profiling and nucleosidase activity screening of soluble crude extracts revealed a deficiency of xanthosine and inosine hydrolysis in the single mutants, with substantial accumulation of xanthosine in one of them. Mixing of the two mutant extracts, and by in vitro activity reconstitution using a mixture of recombinant URH1 and URH2 proteins, both restored activity, thus providing biochemical evidence that at least these two isoforms are needed for inosine and xanthosine hydrolysis. This mutant study demonstrates the utility of in vivo systems for the examination of metabolic activities, with the discovery of the new substrate xanthosine and elucidation of a mechanism for expanding the nucleosidase substrate spectrum. PMID:21599668

  14. Nucleoside-Based Diarylethene Photoswitches: Synthesis and Photochromic Properties.

    PubMed

    Wang, Hai-Xia; Xi, Dan-Dan; Xie, Ming-Sheng; Wang, Hui-Xuan; Qu, Gui-Rong; Guo, Hai-Ming

    2016-07-01

    Diarylethene photoswitches based on the natural nucleoside deoxyadenosine were designed and synthesized. In aqueous solution, some of them exhibited good photochromic properties, including clear changes in color upon irradiation at 365 nm, red-shifts of the absorption wavelength, with good fatigue resistance, thermal stability, conversion efficiency, and base-pairing properties. PMID:27124421

  15. Theophylline inhibition of renal and cerebral nucleoside formation.

    PubMed Central

    Jensen, M. H.

    1981-01-01

    1 Theophylline inhibits the enzymatic formation of purine nucleosides, among these adenosine (dephosphorylated adenosine 5'-monophosphate), in kidney and brain of the rat. 2 Some pharmacological effects of theophylline on regional blood flow and electrophysiological activity of the nervous system may be caused by inhibition of the endogenous formation of adenosine. PMID:7236996

  16. Novel reactivity of Fhit proteins: catalysts for fluorolysis of nucleoside 5'-phosphoramidates and nucleoside 5'-phosphosulfates to generate nucleoside 5'-phosphorofluoridates.

    PubMed

    Wojdyła-Mamoń, Anna M; Zimny, Jarosław; Romanowska, Joanna; Kraszewski, Adam; Stawinski, Jacek; Bieganowski, Paweł; Guranowski, Andrzej

    2015-06-01

    Fragile histidine triad (HIT) proteins (Fhits) occur in all eukaryotes but their function is largely unknown. Human Fhit is presumed to function as a tumour suppressor. Previously, we demonstrated that Fhits catalyse hydrolysis of not only dinucleoside triphosphates but also natural adenosine 5'-phosphoramidate (NH2-pA) and adenosine 5'-phosphosulfate (SO4-pA) as well as synthetic adenosine 5'-phosphorofluoridate (F-pA). In the present study, we describe an Fhit-catalysed displacement of the amino group of nucleoside 5'-phosphoramidates (NH2-pNs) or the sulfate moiety of nucleoside 5'-phosphosulfates (SO4-pNs) by fluoride anion. This results in transient accumulation of the corresponding nucleoside 5'-phosphorofluoridates (F-pNs). Substrate specificity and kinetic characterization of the fluorolytic reactions catalysed by the human Fhit and other examples of involvement of fluoride in the biochemistry of nucleotides are described. Among other HIT proteins, human histidine triad nucleotide-binding protein (Hint1) catalysed fluorolysis of NH2-pA 20 times and human Hint2 40 times more slowly than human Fhit. PMID:25826698

  17. Analogue-to-Digital and Digital-to-Analogue Conversion.

    ERIC Educational Resources Information Center

    Gregory, Martin

    1997-01-01

    Discusses circuits for three-bit and four-bit analogue digital converters and digital analogue converters. These circuits feature slow operating speeds that enable the circuitry to be used to demonstrate the mode of operation using oscilloscopes and signal generators. (DDR)

  18. Kinetic analysis of ligand binding to the Ehrlich cell nucleoside transporter: Pharmacological characterization of allosteric interactions with the sup 3 Hnitrobenzylthioinosine binding site

    SciTech Connect

    Hammond, J.R. )

    1991-06-01

    Kinetic analysis of the binding of {sup 3}Hnitrobenzylthioinosine ({sup 3}H NBMPR) to Ehrlich ascites tumor cell plasma membranes was conducted in the presence and absence of a variety of nucleoside transport inhibitors and substrates. The association of {sup 3}H NBMPR with Ehrlich cell membranes occurred in two distinct phases, possibly reflecting functional conformation changes in the {sup 3}HNBMPR binding site/nucleoside transporter complex. Inhibitors of the equilibrium binding of {sup 3}HNBMPR, tested at submaximal inhibitory concentrations, generally decreased the rate of association of {sup 3}HNBMPR, but the magnitude of this effect varied significantly with the agent tested. Adenosine and diazepam had relatively minor effects on the association rate, whereas dipyridamole and mioflazine slowed the rate dramatically. Inhibitors of nucleoside transport also decreased the rate of dissociation of {sup 3}HNBMPR, with an order of potency significantly different from their relative potencies as inhibitors of the equilibrium binding of {sup 3}HNBMPR. Dilazep, dipyridamole, and mioflazine were effective inhibitors of both {sup 3}HNBMPR dissociation and equilibrium binding. The lidoflazine analogue R75231, on the other hand, had no effect on the rate of dissociation of {sup 3}HNBMPR at concentrations below 300 microM, even though it was one of the most potent inhibitors of {sup 3}HNBMPR binding tested (Ki less than 100 nM). In contrast, a series of natural substrates for the nucleoside transport system enhanced the rate of dissociation of {sup 3}HNBMPR with an order of effectiveness that paralleled their relative affinities for the permeant site of the transporter. The most effective enhancers of {sup 3}HNBMPR dissociation, however, were the benzodiazepines diazepam, chlordiazepoxide, and triazolam.

  19. Synthesis and In Vitro Evaluation of 5-[18F]Fluoroalkyl Pyrimidine Nucleosides for Molecular Imaging of Herpes Simplex Virus Type-1 Thymidine Kinase Reporter Gene Expression

    PubMed Central

    Chacko, Ann-Marie; Qu, Wenchao; Kung, Hank F.

    2014-01-01

    Two novel series of 5-fluoroalkyl-2′-deoxyuridines (FPrDU, FBuDU, FPeDU) and 2′-fluoro-2′-deoxy-5-fluoroalkylarabinouridines (FFPrAU, FFBuAU, FFPeAU), having three, four or five methylene units (propyl, butyl, or pentyl) at C-5, were prepared and tested as reporter probes for imaging HSV1-tk gene expression. The Negishi coupling methodology was employed to efficiently synthesize the radiolabeling precursors. All six 5-[18F]fluoroalkyl pyrimidines were prepared readily from 3-N-benzoyl-3′,5′-di-O-benzoyl-protected 5-O-mesylate precursors in 17–35% radiochemical yield (decay-corrected). In vitro studies highlighted that all six [18F]labeled nucleosides selectively accumulated in cells expressing the HSV1-TK protein, with negligible uptake in control cells. [18F]FPrDU, [18F]FBuDU, [18F]FPeDU, and [18F]FFBuAU had the best uptake profiles. Despite selective accumulation in HSV1-tk expressing cells, all 5-fluoroalkyl pyrimidine nucleosides had low to negligible cytotoxic activity (CC50>1000–209 μM). Ultimately, results demonstrated that 5-[18F]fluoropropyl, [18F]fluorobutyl, and [18F]fluoropentyl pyrimidine nucleosides have potential as in vivo HSV1-TK PET reporter probes over a dynamic range of reporter gene expression levels. PMID:18800764

  20. Long-term efficacy of nucleoside monotherapy in preventing HBV infection in HBsAg-negative recipients of anti-HBc-positive donor livers

    PubMed Central

    Chotiyaputta, Watcharasak; Pelletier, Shawn J.; Fontana, Robert J.

    2010-01-01

    Background and aim Transmission of hepatitis B virus (HBV) infection occurs in up to 87.5% of HBsAg-negative recipients of anti-HBc-positive donor livers in the absence of HBV prophylaxis. There is no standardized prophylactic regimen to prevent HBV infection in this setting. The aim of this study was to determine the long-term efficacy of nucleoside analogue to prevent HBV infection in this setting. Methods A retrospective study of HBsAg-negative patients receiving liver transplantation (LT) from anti-HBc-positive donors during a 10-year period. Results Twenty patients were studied, mean age was 50.2 ± 8.3 years, 40% were men, and 90% were Caucasian. The median MELD score at the time of LT was 18 (12–40). None of the patients received hepatitis B immune globulin. Eighteen patients received nucleoside analogue monotherapy: 10 received lamivudine and 8 received entecavir. None of these 18 patients developed HBV infection after a median follow up of 32 (1–75) months. One patient received a second course of hepatitis B vaccine 50 months after LT with anti-HBs titer above 1,000 mIU/mL. Lamivudine was discontinued and the patient remained HBsAg negative 18 months after withdrawal of lamivudine. Two patients who were anti-HBs positive before LT were not started on HBV prophylaxis after LT; both developed HBV infection after LT. Conclusions Nucleoside monotherapy is sufficient in preventing HBV infection in HBsAg-negative recipients of anti-HBc-positive donor livers. HBV prophylaxis is necessary in anti-HBs-positive recipients of anti-HBc-positive donor livers. PMID:21286341

  1. Synthesis and Conformational Analysis of Locked Carbocyclic Analogues of 1,3-Diazepinone Riboside, a High-Affinity Cytidine Deaminase Inhibitor

    PubMed Central

    2009-01-01

    Cytidine deaminase (CDA) catalyzes the deamination of cytidine via a hydrated transition-state intermediate that results from the nucleophilic attack of zinc-bound water at the active site. Nucleoside analogues where the leaving NH3 group is replaced by a proton and prevent conversion of the transition state to product are very potent inhibitors of the enzyme. However, stable carbocyclic versions of these analogues are less effective as the role of the ribose in facilitating formation of hydrated species is abolished. The discovery that a 1,3-diazepinone riboside (4) operated as a tight-binding inhibitor of CDA independent of hydration provided the opportunity to study novel inhibitors built as conformationally locked, carbocyclic 1,3-diazepinone nucleosides to determine the enzyme’s conformational preference for a specific form of sugar pucker. This work describes the synthesis of two target bicyclo[3.1.0]hexane nucleosides, locked as north (5) and south (6) conformers, as well as a flexible analogue (7) built with a cyclopentane ring. The seven-membered 1,3-diazepinone ring in all the three targets was built from the corresponding benzoyl-protected carbocyclic bis-allyl ureas by ring-closing metathesis. The results demonstrate CDA’s binding preference for a south sugar pucker in agreement with the high-resolution crystal structures of other CDA inhibitors bound at the active site. PMID:19618900

  2. Selective loss of nucleoside carrier expression in rat hepatocarcinomas.

    PubMed

    Dragan, Y; Valdés, R; Gomez-Angelats, M; Felipe, A; Javier Casado, F; Pitot, H; Pastor-Anglada, M

    2000-08-01

    Evidence that hepatoma cell lines show differential expression of concentrative nucleoside transporters (CNT1 and CNT2) prompted us to study the transporter proteins in 2 models of hepatocarcinogenesis, the chemically induced Solt and Farber model and the albumin-SV40 large T antigen (Alb-SV40) transgenic rat. CNT1 expression was lower in tumor biopsy specimens from Alb-SV40 rat livers than in normal tissue. Immunocytochemistry revealed that the CNT1 protein was indeed absent in the tumor lesions. CNT1 was also absent in a cell line, L25, derived from the Alb-SV40 transgenic rat liver tumors, whereas another cell line, L37, derived from the normal-appearing parenchyma, retained the expression of both carrier isoforms. The protein expression correlated with the nucleoside transport properties of these cell lines. Moreover, although CNT2 expression was highly dependent on the growth characteristics of the 2 cell lines, as was CNT1 (albeit to a lower extent) in L37 cells, it was not expressed in L25 cells at any stage of cell growth. In contrast to the transgenic model of hepatocarcinogenesis, in the chemically induced tumors the expression of CNT2 was lower, although still detectable. In summary, these data indicate that hepatocarcinogenesis leads to a selective loss or diminished expression of nucleoside carrier isoforms, a feature that may be relevant to our understanding of the molecular basis of the bioavailability of those drugs that are nucleoside derivatives and may be substrates of these carriers. The transport properties and isoform-expression profile of the L25 and L37 cell lines make them suitable hepatocyte culture models with which to study nucleoside transport processes and drug sensitivity. PMID:10915730

  3. Sensing Metal Ions with DNA Building Blocks: Fluorescent Pyridobenzimidazole Nucleosides

    PubMed Central

    Kim, Su Jeong; Kool, Eric T.

    2008-01-01

    We describe novel fluorescent N-deoxyribosides (1 and 2) having 2-pyrido-2-benzimidazole and 2-quino-2-benzimidazole as aglycones. The compounds were prepared from the previously unknown heterocyclic precursors and Hoffer’s chlorosugar, yielding alpha anomers as the chief products. X-ray crystal structures confirmed the geometry, and showed that the pyridine and benzimidazole ring systems deviated from coplanarity in the solid state by 154° and 140°, respectively. In methanol the compounds 1 and 2 had absorption maxima at 360 and 370 nm respectively, and emission maxima at 494 and 539 nm. Experiments revealed varied fluorescence responses of the nucleosides to a panel of seventeen monovalent, divalent and trivalent metal ions in methanol. One or both of the nucleosides showed significant changes with ten of the metal ions. The most pronounced spectral changes for ligand-nucleoside 1 included red shifts in fluorescence (Au+, Au3+), strong quenching (Cu2+, Ni2+, Pt2+), and in substantial enhancements in emission intensity coupled with redshifts (Ag+, Cd2+, Zn2+). The greatest spectral changes for ligand-nucleoside 2 included a redshift in fluorescence (Ag+), a blueshift (Cd2+), strong quenching (Pd2+, Pt2+), and in substantial enhancements in emission intensity coupled with a blueshift (Zn2+). The compounds could be readily incorporated into oligodeoxynucleotides, where an initial study revealed that they retained sensitivity to metal ions in aqueous solution, and demonstrated possible cooperative sensing behavior with several ions. The two free nucleosides alone can act as differential sensors for at multiple metal ions, and they are potentially useful monomers for contributing metal ion sensing capability to DNAs. PMID:16669686

  4. Synthesis of nucleoside 3'-(S-alkyl phosphorothioates) and their use as substrates for nucleases.

    PubMed

    Saba, D; Dekker, C A

    1981-09-15

    The synthesis of cytidine, uridine, guanosine, and adenosine 3'-(S-methyl phosphorothioates) by treatment of the 2',5'-di-O-(4-methoxytetrahydropyran-4-yl)ribonucleosides with 2-(methylthio 4H-1,3,2-benzodioxaphosphorin 2-oxide is described. These nucleotide analogues are stable compounds both in the solid state and the neutral aqueous solution. All four of these compounds are degraded by RNase T2 to the parent nucleotides and methanethiol. In addition, cytidine and uridine 3'-(S-methyl phosphorothioates) are substrates for bovine pancreatic ribonuclease and guanosine 3'-(S-methyl phosphorothioate) is a substrate for RNase T1 and RNase U1. When used in conjunction with a chromophore-producing reagent, nucleoside 3'-(S-methyl phosphorothioates) provide a means for direct kinetic measurement of ribonuclease activity over a wide pH range (pH 2-9). The reactivities of these substrates with ribonucleases are compared to the reactivities of other synthetic substrates as well as a number of natural substrates. The utility of ribonucleoside 3'-(S-methyl phosphorothioates) as substrates for the assay of ribonucleases is discussed. PMID:6271188

  5. Immobilized purine nucleoside phosphorylase from Schistosoma mansoni for specific inhibition studies.

    PubMed

    de Moraes, Marcela Cristina; Cardoso, Carmen L; Cass, Quezia B

    2013-05-01

    The parasite Schistosoma mansoni (Sm) depends exclusively on the salvage pathway for its purine requirements. The enzyme purine nucleoside phosphorylase (PNP) is, therefore, a promising target for development of antischistosomal agents and an assay for screening of inhibitors. To enable this, immobilized SmPNP reactors were produced. By quantification of hypoxanthine by liquid chromatography, kinetic constants (K M) for the substrate inosine were determined for the free and immobilized enzyme as 110 ± 6.90 μmol L (-1) and 164 ± 13.4 μmol L (-1), respectively, indicating that immobilization did not affect enzyme activity. Furthermore, the enzyme retained 25 % of its activity after four months. Non-Michaelis kinetics for the phosphate substrate, and capacity for Pi-independent hydrolysis were also demonstrated, despite the low rate of enzymatic catalysis. Use of an SmPNP immobilized enzyme reactor (IMER) for inhibitor-screening assays was demonstrated with a small library of 9-deazaguanine analogues. The method had high selectivity and specificity compared with screening by use of the free enzyme by the Kalckar method, and furnished results without the need for verification of the absence of false positives. PMID:23535739

  6. A New Subfamily of Polyphosphate Kinase 2 (Class III PPK2) Catalyzes both Nucleoside Monophosphate Phosphorylation and Nucleoside Diphosphate Phosphorylation

    PubMed Central

    Motomura, Kei; Hirota, Ryuichi; Okada, Mai; Ikeda, Takeshi; Ishida, Takenori

    2014-01-01

    Inorganic polyphosphate (polyP) is a linear polymer of tens to hundreds of phosphate (Pi) residues linked by “high-energy” phosphoanhydride bonds as in ATP. PolyP kinases, responsible for the synthesis and utilization of polyP, are divided into two families (PPK1 and PPK2) due to differences in amino acid sequence and kinetic properties. PPK2 catalyzes preferentially polyP-driven nucleotide phosphorylation (utilization of polyP), which is important for the survival of microbial cells under conditions of stress or pathogenesis. Phylogenetic analysis suggested that the PPK2 family could be divided into three subfamilies (classes I, II, and III). Class I and II PPK2s catalyze nucleoside diphosphate and nucleoside monophosphate phosphorylation, respectively. Here, we demonstrated that class III PPK2 catalyzes both nucleoside monophosphate and nucleoside diphosphate phosphorylation, thereby enabling us to synthesize ATP from AMP by a single enzyme. Moreover, class III PPK2 showed broad substrate specificity over purine and pyrimidine bases. This is the first demonstration that class III PPK2 possesses both class I and II activities. PMID:24532069

  7. Synthesis and Comparative Study of Anti-Adenoviral Activity of 6-Azacytidine and Its Analogues.

    PubMed

    Alexeeva, Inna; Nosach, Lydia; Palchykovska, Larisa; Usenko, Lyubov; Povnitsa, Olga

    2015-01-01

    This paper presents the results of synthesis and study of cytotoxicity and the anti-adenoviral activity of new N4-derivatives of 6-azacytidine and its α-L-glycopyranosyl analogues obtained by the simplified one-pot version of the silyl condensation method. The resulting acylated 4-methylmercapto-1,2,4-triazin-3(2Н)-one glycosides then underwent the amination and/or ammonolysis to provide 6-azacytidine glycoside analogues (2-6, 12, 15, 17) and compounds with modifications at both base and sugar fragments (11, 15). The evaluation of cytotoxicity and antiviral activity of new compounds against AdV5 showed high selectivity indexes for N4-methyl-6-azacytidine (2) and N,O-tetraacetyl-6-azacytidine (8). High anti-adenoviral activity of N4-methyl-6-azacytidine as well as very low cytotoxicity may suggest its further investigation as potential compound for the therapy of AdV infection. PMID:26167665

  8. Phosphonate analogues of aminoacyl adenylates.

    PubMed Central

    Southgate, C C; Dixon, H B

    1978-01-01

    Phosphonomethyl analogues of glycyl phosphate and valyl phosphate, i.e. NH2-CHR-CO-CH2-PO(OH)2, were synthesized and esterified with adenosine to give analogues of aminoacyl adenylates. The interaction of these adenylate analogues with valyl-tRNA synthetase from Escherichia coli was studied by fluorescence titration. The analogue of valyl phosphate has an affinity for the enzyme comparable with that of valine, but that of valyl adenylate is bound much less tightly than either valyl adenylate or corresponding derivative of valinol. The affinity of the analogue of glycyl adenylate was too low to be measured. We conclude that this enzyme interacts specifically with both the side chain and the anhydride linkage of the adenylate intermediate. PMID:743207

  9. Expanding Radical SAM Chemistry by Using Radical Addition Reactions and SAM Analogues.

    PubMed

    Ji, Xinjian; Li, Yongzhen; Xie, Liqi; Lu, Haojie; Ding, Wei; Zhang, Qi

    2016-09-19

    Radical S-adenosyl-l-methionine (SAM) enzymes utilize a [4Fe-4S] cluster to bind SAM and reductively cleave its carbon-sulfur bond to produce a highly reactive 5'-deoxyadenosyl (dAdo) radical. In almost all cases, the dAdo radical abstracts a hydrogen atom from the substrates or from enzymes, thereby initiating a highly diverse array of reactions. Herein, we report a change of the dAdo radical-based chemistry from hydrogen abstraction to radical addition in the reaction of the radical SAM enzyme NosL. This change was achieved by using a substrate analogue containing an olefin moiety. We also showed that two SAM analogues containing different nucleoside functionalities initiate the radical-based reactions with high efficiencies. The radical adduct with the olefin produced in the reaction was found to undergo two divergent reactions, and the mechanistic insights into this process were investigated in detail. Our study demonstrates a promising strategy in expanding radical SAM chemistry, providing an effective way to access nucleoside-containing compounds by using radical SAM-dependent reactions. PMID:27573794

  10. NASA/ESMD Analogue Mission Plans

    NASA Technical Reports Server (NTRS)

    Hoffman, Stephen J.

    2007-01-01

    A viewgraph presentation exploring Earth and its analogues is shown. The topics include: 1) ESMD Goals for the Use of Earth Analogues; 2) Stakeholders Summary; 3) Issues with Current Analogue Situation; 4) Current state of Analogues; 5) External Implementation Plan (Second Step); 6) Recent Progress in Utilizing Analogues; 7) Website Layout Example-Home Page; 8) Website Layout Example-Analogue Site; 9) Website Layout Example-Analogue Mission; 10) Objectives of ARDIG Analog Initiatives; 11) Future Plans; 12) Example: Cold-Trap Sample Return; 13) Example: Site Characterization Matrix; 14) Integrated Analogue Studies-Prerequisites for Human Exploration; and 15) Rating Scale Definitions.

  11. Synthesis and Evaluation of Novel Acyclic Nucleoside Phosphonates as Inhibitors of Plasmodium falciparum and Human 6-Oxopurine Phosphoribosyltransferases.

    PubMed

    Kaiser, Martin M; Hocková, Dana; Wang, Tzu-Hsuan; Dračínský, Martin; Poštová-Slavětínská, Lenka; Procházková, Eliška; Edstein, Michael D; Chavchich, Marina; Keough, Dianne T; Guddat, Luke W; Janeba, Zlatko

    2015-10-01

    Acyclic nucleoside phosphonates (ANPs) are a promising class of antimalarial therapeutic drug leads that exhibit a wide variety of Ki values for Plasmodium falciparum (Pf) and human hypoxanthine-guanine-(xanthine) phosphoribosyltransferases [HG(X)PRTs]. A novel series of ANPs, analogues of previously reported 2-(phosphonoethoxy)ethyl (PEE) and (R,S)-3-hydroxy-2-(phosphonomethoxy)propyl (HPMP) derivatives, were designed and synthesized to evaluate their ability to act as inhibitors of these enzymes and to extend our ongoing antimalarial structure-activity relationship studies. In this series, (S)-3-hydroxy-2-(phosphonoethoxy)propyl (HPEP), (S)-2-(phosphonomethoxy)propanoic acid (CPME), or (S)-2-(phosphonoethoxy)propanoic acid (CPEE) are the acyclic moieties. Of this group, (S)-3-hydroxy-2-(phosphonoethoxy)propylguanine (HPEPG) exhibits the highest potency for PfHGXPRT, with a Ki value of 0.1 μM and a Ki value for human HGPRT of 0.6 μM. The crystal structures of HPEPG and HPEPHx (where Hx=hypoxanthine) in complex with human HGPRT were obtained, showing specific interactions with active site residues. Prodrugs for the HPEP and CPEE analogues were synthesized and tested for in vitro antimalarial activity. The lowest IC50 value (22 μM) in a chloroquine-resistant strain was observed for the bis-amidate prodrug of HPEPG. PMID:26368337

  12. 20(S)-Protopanaxadiol (PPD) analogues chemosensitize multidrug-resistant cancer cells to clinical anticancer drugs.

    PubMed

    Liu, Junhua; Wang, Xu; Liu, Peng; Deng, Rongxin; Lei, Min; Chen, Wantao; Hu, Lihong

    2013-07-15

    Novel 20(S)-protopanoxadiol (PPD) analogues were designed, synthesized, and evaluated for the chemosensitizing activity against a multidrug resistant (MDR) cell line (KBvcr) overexpressing P-glycoprotein (P-gp). Structure-activity relationship analysis showed that aromatic substituted aliphatic amine at the 24-positions (groups V) effectively and significantly sensitized P-gp overexpressing multidrug resistant (MDR) cells to anticancer drugs, such as docetaxel (DOC), vincristine (VCR), and adriamycin (ADM). PPD derivatives 12 and 18 showed 1.3-2.6 times more effective reversal ability than verapamil (VER) for DOC and VCR. Importantly, no cytotoxicity was observed by the active PPD analogues (5μM) against both non-MDR and MDR cells, suggesting that PPD analogues serve as novel lead compounds toward a potent and safe resistance modulator. Moreover, a preliminary mechanism study demonstrated that the chemosensitizing activity of PPD analogues results from inhibition of P-glycoprotein (P-gp) overexpressed in MDR cancer cells. PMID:23683834

  13. d- and l-2′,3′-Didehydro-2′,3′-Dideoxy-3′-Fluoro-Carbocyclic Nucleosides: Synthesis, Anti-HIV Activity and Mechanism of Resistance

    PubMed Central

    Wang, Jianing; Jin, Yunho; Rapp, Kimberly L.; Schinazi, Raymond F.; Chu, Chung K.

    2008-01-01

    Introducing 2′-fluoro substitution on the 2′,3′-double bond in carbocyclic nucleosides has provided biologically interesting compounds with potent anti-HIV activity. As an extension of our previous works in the discovery of anti-HIV agents, d- and l-2′,3′-unsaturated 3′-fluoro carbocyclic nucleosides were synthesized and evaluated against HIV-1 in human peripheral blood mononuclear (PBM) cells. Among the synthesized l-series nucleosides, compounds 18, 19, 26, 28 exhibited moderate antiviral activity (EC50 7.1 μM, 6.4 μM, 10.3 μM and 20.7 μM, respectively), while among the d-series, the guanosine analogue (35, d-3′-F-C-d4G) exhibited the most potent anti-HIV activity (EC50 0.4 μM, EC90 2.8 μM). However, the guanosine analogue 35 was cross-resistant to the lamivudine-resistant variants (HIV-1M184V). Molecular modeling studies suggest that hydrophobic interaction as well as hydrogen bonding stabilize the binding of compound 35 in the active site of wild type HIV reverse transcriptase (HIV-RT). In the case of l-nucleosides, these two effects are opposite which results in a loss of binding affinity. According to the molecular modeling studies, cross-resistance of d-3′-F-C-d4G (35) to M184V mutant may be caused by the realignment of the primer and template in the HIV-RTM184V interaction, which destabilizes the RT-inhibitor triphosphate complex, resulting in a significant reduction in anti-HIV activity of the d-guanine derivative 35. PMID:17373782

  14. Modified Nucleoside Triphosphates for In-vitro Selection Techniques

    PubMed Central

    Dellafiore, María A.; Montserrat, Javier M.; Iribarren, Adolfo M.

    2016-01-01

    The development of SELEX (Selective Enhancement of Ligands by Exponential Enrichment) provides a powerful tool for the search of functional oligonucleotides with the ability to bind ligands with high affinity and selectivity (aptamers) and for the discovery of nucleic acid sequences with diverse enzymatic activities (ribozymes and DNAzymes). This technique has been extensively applied to the selection of natural DNA or RNA molecules but, in order to improve chemical and structural diversity as well as for particular applications where further chemical or biological stability is necessary, the extension of this strategy to modified oligonucleotides is desirable. Taking into account these needs, this review intends to collect the research carried out during the past years, focusing mainly on the use of modified nucleotides in SELEX and the development of mutant enzymes for broadening nucleoside triphosphates acceptance. In addition, comments regarding the synthesis of modified nucleoside triphosphate will be briefly discussed. PMID:27200340

  15. A Novel and Fast Purification Method for Nucleoside Transporters.

    PubMed

    Hao, Zhenyu; Thomsen, Maren; Postis, Vincent L G; Lesiuk, Amelia; Sharples, David; Wang, Yingying; Bartlam, Mark; Goldman, Adrian

    2016-01-01

    Nucleoside transporters (NTs) play critical biological roles in humans, and to understand the molecular mechanism of nucleoside transport requires high-resolution structural information. However, the main bottleneck for structural analysis of NTs is the production of pure, stable, and high quality native protein for crystallization trials. Here we report a novel membrane protein expression and purification strategy, including construction of a high-yield membrane protein expression vector, and a new and fast purification protocol for NTs. The advantages of this strategy are the improved time efficiency, leading to high quality, active, stable membrane proteins, and the efficient use of reagents and consumables. Our strategy might serve as a useful point of reference for investigating NTs and other membrane proteins by clarifying the technical points of vector construction and improvements of membrane protein expression and purification. PMID:27376071

  16. A Novel and Fast Purification Method for Nucleoside Transporters

    PubMed Central

    Hao, Zhenyu; Thomsen, Maren; Postis, Vincent L. G.; Lesiuk, Amelia; Sharples, David; Wang, Yingying; Bartlam, Mark; Goldman, Adrian

    2016-01-01

    Nucleoside transporters (NTs) play critical biological roles in humans, and to understand the molecular mechanism of nucleoside transport requires high-resolution structural information. However, the main bottleneck for structural analysis of NTs is the production of pure, stable, and high quality native protein for crystallization trials. Here we report a novel membrane protein expression and purification strategy, including construction of a high-yield membrane protein expression vector, and a new and fast purification protocol for NTs. The advantages of this strategy are the improved time efficiency, leading to high quality, active, stable membrane proteins, and the efficient use of reagents and consumables. Our strategy might serve as a useful point of reference for investigating NTs and other membrane proteins by clarifying the technical points of vector construction and improvements of membrane protein expression and purification. PMID:27376071

  17. Synthetic strategies toward carbocyclic purine-pyrimidine hybrid nucleosides.

    PubMed

    Sadler, Joshua M; Mosley, Sylvester L; Dorgan, Kathleen M; Zhou, Zhaohui Sunny; Seley-Radtke, Katherine L

    2009-08-01

    The blending of key structural features from the purine and pyrimidine nucleobase scaffolds gives rise to a new class of hybrid nucleosides. The purine-pyrimidine hybrid nucleosides can be viewed as either N-3 ribosylated purines or 5,6-disubstituted pyrimidines, thus recognition by both purine- and pyrimidine-metabolizing enzymes is possible. Given the increasing reports of the development of resistance in many enzymatic systems, a drug that could be recognized by more than one enzyme could prove highly advantageous in overcoming resistance mechanisms related to binding site mutations. In that regard, the design, synthesis and results of preliminary biological activity for a series of carbocyclic uracil derivatives with either a fused imidazole or thiazole ring are presented herein. PMID:19592260

  18. Synthetic Strategies Toward Carbocyclic Purine-Pyrimidine Hybrid Nucleosides

    PubMed Central

    Sadler, Joshua M.; Mosley, Sylvester L.; Dorgan, Kathleen M.; Zhou, Zhaohui Sunny; Seley-Radtke, Katherine L.

    2009-01-01

    The blending of key structural features from the purine and pyrimidine nucleobase scaffolds gives rise to a new class of hybrid nucleosides. The purine-pyrimidine hybrid nucleosides can be viewed as either N-3 ribosylated purines or 5,6-disubstituted pyrimidines, thus recognition by both purine- and pyrimidine-metabolizing enzymes is possible. Given the increasing reports of the development of resistance in many enzymatic systems, a drug that could be recognized by more than one enzyme could prove highly advantageous in overcoming resistance mechanisms related to binding site mutations. In that regard, the design, synthesis and results of preliminary biological activity for a series of carbocyclic uracil derivatives with either a fused imidazole or thiazole ring are presented herein. PMID:19592260

  19. Modified Nucleoside Triphosphates for In-vitro Selection Techniques.

    PubMed

    Dellafiore, María A; Montserrat, Javier M; Iribarren, Adolfo M

    2016-01-01

    The development of SELEX (Selective Enhancement of Ligands by Exponential Enrichment) provides a powerful tool for the search of functional oligonucleotides with the ability to bind ligands with high affinity and selectivity (aptamers) and for the discovery of nucleic acid sequences with diverse enzymatic activities (ribozymes and DNAzymes). This technique has been extensively applied to the selection of natural DNA or RNA molecules but, in order to improve chemical and structural diversity as well as for particular applications where further chemical or biological stability is necessary, the extension of this strategy to modified oligonucleotides is desirable. Taking into account these needs, this review intends to collect the research carried out during the past years, focusing mainly on the use of modified nucleotides in SELEX and the development of mutant enzymes for broadening nucleoside triphosphates acceptance. In addition, comments regarding the synthesis of modified nucleoside triphosphate will be briefly discussed. PMID:27200340

  20. Compositions containing nucleosides and manganese and their uses

    SciTech Connect

    Daly, Michael J.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Levine, Rodney L.; Wehr, Nancy B.

    2015-11-17

    This invention encompasses methods of preserving protein function by contacting a protein with a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e.g., manganese). In addition, the invention encompasses methods of treating and/or preventing a side effect of radiation exposure and methods of preventing a side effect of radiotherapy comprising administration of a pharmaceutically effective amount of a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e.g., manganese) to a subject in need thereof. The compositions may comprise D. radiodurans extracts.

  1. Modified Nucleoside Triphosphates for in-vitro Selection Techniques

    NASA Astrophysics Data System (ADS)

    Iribarren, Adolfo; Dellafiore, María; Montserrat, Javier

    2016-05-01

    The development of SELEX (Selective Enhancement of Ligands by Exponential Enrichment) provides a powerful tool for the search of functional oligonucleotides with the ability to bind ligands with high affinity and selectivity (aptamers) and for the discovery of nucleic acid sequences with diverse enzymatic activities (ribozymes and DNAzymes). This technique has been extensively applied to the selection of natural DNA or RNA molecules but, in order to improve chemical and structural diversity as well as for particular applications where further chemical or biological stability is necessary, the extension of this strategy to modified oligonucleotides is desirable. Taking into account these needs, this review intends to collect the research carried out during the past years, focusing mainly on the use of modified nucleotides in SELEX and the development of mutant enzymes for broadening nucleoside triphosphates acceptance. In addition, comments regarding the synthesis of modified nucleoside triphosphate will be briefly discussed.

  2. Localization of GFP-tagged concentrative nucleoside transporters in a renal polarized epithelial cell line.

    PubMed

    Mangravite, L M; Lipschutz, J H; Mostov, K E; Giacomini, K M

    2001-05-01

    Many nucleosides undergo active reabsorption within the kidney, probably via nucleoside transporters. To date, two concentrative nucleoside transporters have been cloned, the sodium-dependent purine-selective nucleoside transporter (SPNT) and concentrative nucleoside transporter 1 (CNT1). We report the stable expression of green fluorescence protein (GFP)-tagged SPNT and CNT1 in Madin-Darby canine kidney (MDCK) cells, a polarized renal epithelial line. We demonstrate that the GFP tag does not alter the substrate selectivity and only modestly affects the kinetic activity of the transporters. By using confocal microscopy and functional studies, both SPNT and CNT1 are localized primarily to the apical membrane of MDCK and LLC-PK(1) cells. Apical localization of these transporters suggests a role in renal nucleoside reabsorption and regulation of tubular function via the adenosine pathway. PMID:11292631

  3. A comparison of enzymatic phosphorylation and phosphatidylation of beta-L- and beta-D-nucleosides.

    PubMed

    Birichevskaya, Larisa L; Kvach, Sergei V; Sivets, Grigorii G; Kalinichenko, Elena N; Zinchenko, Anatoly I; Mikhailopulo, Igor A

    2007-04-01

    Enzymatic 5'-monophosphorylation and 5'-phosphatidylation of a number of beta-L- and beta-D-nucleosides was investigated. The first reaction, catalyzed by nucleoside phosphotransferase (NPT) from Erwinia herbicola, consisted of the transfer of the phosphate residue from p-nitrophenylphosphate (p-NPP) to the 5'-hydroxyl group of nucleoside; the second was the phospholipase D (PLD)-catalyzed transphosphatidylation of L-alpha-lecithin with a series of beta-L- and beta-D-nucleosides as the phosphatidyl acceptor resulted in the formation of the respective phospholipid-nucleoside conjugates. Some beta-L-nucleosides displayed similar or even higher substrate activity compared to the beta-D-enantiomers. PMID:17206374

  4. Inhibition of Homologous Recombination with Vorinostat Synergistically Enhances Ganciclovir Cytotoxicity

    PubMed Central

    Ladd, Brendon; Ackroyd, Jeffrey J.; Hicks, J. Kevin; Canman, Christine E.; Flanagan, Sheryl A.; Shewach, Donna S.

    2014-01-01

    The nucleoside analog ganciclovir (GCV) elicits cytotoxicity in tumor cells via a novel mechanism in which drug incorporation into DNA produces minimal disruption of replication, but numerous DNA double strand breaks occur during the second S-phase after drug exposure. We propose that homologous recombination (HR), a major repair pathway for DNA double strand breaks, can prevent GCV-induced DNA damage, and that inhibition of HR will enhance cytotoxicity with GCV. Survival after GCV treatment in cells expressing a herpes simplex virus thymidine kinase was strongly dependent on HR (>14-fold decrease in IC50 in HR-deficient vs. HR-proficient CHO cells). In a homologous recombination reporter assay, the histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA; vorinostat), decreased HR repair events up to 85%. SAHA plus GCV produced synergistic cytotoxicity in U251tk human glioblastoma cells. Elucidation of the synergistic mechanism demonstrated that SAHA produced a concentration-dependent decrease in the HR proteins Rad51 and CtIP. GCV alone produced numerous Rad51 foci, demonstrating activation of HR. However, the addition of SAHA blocked GCV-induced Rad51 foci formation completely and increased γH2AX, a marker of DNA double strand breaks. SAHA plus GCV also produced synergistic cytotoxicity in HR-proficient CHO cells, but the combination was antagonistic or additive in HR-deficient CHO cells. Collectively, these data demonstrate that HR promotes survival with GCV and compromise of HR by SAHA results in synergistic cytotoxicity, revealing a new mechanism for enhancing anticancer activity with GCV. PMID:24231389

  5. Synthesis of oligodeoxyribonucleotides using N-benzyloxycarbonyl-blocked nucleosides

    SciTech Connect

    Watkins, B.E.; Kiely, J.S.; Rapoport, H.

    1982-10-20

    The exo amino groups of 2'-deoxyadenosine and 2'-deoxycytidine have been blocked as the benzyl carbamates, and 2'-deoxyguanosine has been blocked as its 2-N-(benzyloxycarbonyl)carbamate and 6-O-benzyl ether. These blocked nucleosides have been incorporated into an efficient oligodeoxyribonucleotide synthetic scheme, and the resulting oligomer has been successfully deblocked by using transfer hydrogenation. The deblocking conditions result in no reduction of the pyrimidine bases.

  6. Nucleobase and nucleoside transport and integration into plant metabolism

    PubMed Central

    Girke, Christopher; Daumann, Manuel; Niopek-Witz, Sandra; Möhlmann, Torsten

    2014-01-01

    Nucleotide metabolism is an essential process in all living organisms. Besides newly synthesized nucleotides, the recycling (salvage) of partially degraded nucleotides, i.e., nucleosides and nucleobases serves to keep the homeostasis of the nucleotide pool. Both types of metabolites are substrates of at least six families of transport proteins in Arabidopsis thaliana (Arabidopsis) with a total of 49 members. In the last years several members of such transport proteins have been analyzed allowing to present a more detailed picture of nucleoside and nucleobase transport and the physiological function of these processes. Besides functioning in nucleotide metabolism it turned out that individual members of the before named transporters exhibit the capacity to transport a wide range of different substrates including vitamins and phytohormones. The aim of this review is to summarize the current knowledge on nucleobase and nucleoside transport processes in plants and integrate this into nucleotide metabolism in general. Thereby, we will focus on those proteins which have been characterized at the biochemical level. PMID:25250038

  7. Effects of halides on reaction of nucleosides with ozone.

    PubMed

    Suzuki, Toshinori; Kaya, Eriko; Inukai, Michiyo

    2012-01-01

    Ozone (O(3)), a major component of photochemical oxidants, is used recently as a deodorizer in living spaces. It has been reported that O(3) can directly react with DNA, causing mutagenesis in human cells and carcinogenesis in mice. However, little is known about the effects of coexistent ions in the reaction of O(3). In the present study, we analyzed the effects of halides on the reaction of O(3) with nucleosides using reversed-phase high-performance liquid chromatography with ultraviolet detection. When aqueous O(3) solution was added to a nucleoside mixture in potassium phosphate buffer (pH 7.3), the nucleosides were consumed with the following decreasing order of importance: dGuo > Thd > dCyd > dAdo. The effects of addition of fluoride and chloride in the system were slight. Bromide suppressed the reactions of dGuo, Thd, and dAdo but enhanced the reaction of dCyd. The major products were 5-hydroxy-2'-deoxycytidine, 5-bromo-2'-deoxycytidine, and 8-bromo-2'-deoxyguanosine. The time course and pH dependence of the product yield indicated formation of hypobromous acid as the reactive agent. Iodide suppressed all the reactions effectively. The results suggest that bromide may alter the mutation spectrum by O(3) in humans. PMID:22646086

  8. Total Synthesis and Biological Studies of TMC-205 and Analogues as Anticancer Agents and Activators of SV40 Promoter

    PubMed Central

    2014-01-01

    TMC-205 is a natural fungal metabolite with antiproliferative activity against cancer cell lines. The light- and air-sensitivity prevented in-depth exploitation of this novel indole derivative. Herein, we report the first synthesis of TMC-205. On the basis of its reactivity with reactive oxygen species, we developed air-stable analogues of TMC-205. These analogues are 2–8-fold more cytotoxic than TMC-205 against HCT-116 colon cancer cell line. Importantly, at noncytotoxic dose levels, these analogues activated the transcription of luciferase reporter gene driven by simian virus 40 promoter (SV40). Further, these small molecules also inhibit firefly luciferase, presumably by direct interaction. PMID:25147604

  9. Discovery of Mandelalide E and Determinants of Cytotoxicity for the Mandelalide Series.

    PubMed

    Nazari, Mohamad; Serrill, Jeffrey D; Sikorska, Justyna; Ye, Tao; Ishmael, Jane E; McPhail, Kerry L

    2016-03-18

    Recollection of the tunicate source of the mandelalides has provided new and known analogues that have facilitated expanded analyses of the disputed cancer cytotoxicity of mandelalide A following a number of recent reported total syntheses. Using newly characterized mandelalide E, reisolated natural mandelalides B and C, and synthetic mandelalide A, the cytotoxicity of the mandelalides is demonstrated to be strongly influenced by compound glycosylation and assay cell density. Glycosylated mandelalides reduced the viability of human cancer cells cultured at a high starting density with a rank order of potency A > B ≫ E, yet display dramatically reduced cytotoxic efficacy against low density cultures. PMID:26914981

  10. Nucleoside transport at the blood-testis barrier studied with primary-cultured sertoli cells.

    PubMed

    Kato, Ryo; Maeda, Tomoji; Akaike, Toshihiro; Tamai, Ikumi

    2005-02-01

    Nucleosides are essential for nucleotide synthesis in testicular spermatogenesis. In the present study, the mechanism of the supply of nucleosides to the testicular system across the blood-testis barrier was studied using primary-cultured Sertoli cells from rats and TM4 cells from mice. Uptake of uridine by these cells was time- and concentration-dependent. Uridine uptake was decreased under Na(+)-free conditions, and the system was presumed to be high affinity, indicating an Na(+)-dependent concentrative nucleoside transporter (CNT) is involved. On the other hand, nitrobenzylthioinosine, a potent inhibitor of Na(+)-independent equilibrative nucleoside transporters (ENTs), inhibited uridine uptake by the Sertoli cells in a concentration-dependent manner. Expression of nucleoside transporters ENT1, ENT2, ENT3, CNT1, CNT2, and CNT3 was detected in Sertoli cells by reverse transcriptase-polymerase chain reaction analysis. Inhibition studies of the uptake of uridine by various nucleosides both in the presence and absence of Na(+) indicated that the most of those expressed nucleoside transporters, ENTs and CNTs, are involved functionally. These results demonstrated that Sertoli cells are equipped with multiple nucleoside transport systems, including ENT1, ENT2, and CNTs, to provide nucleosides for spermatogenesis. PMID:15547112

  11. Nucleosides of 4-methylthio-1,2,3-triazol-5-yl-carboxylic acid derivatives

    SciTech Connect

    Shingarova, I.D.; Yartseva, I.V.; Preobrazhenskaya, M.N.

    1987-08-01

    2-..beta..-D-Ribofuranosyl-4-methylthio-5-methoxycarbonyl-1,2,3-triazole was obtained by fusing 4-methylthio-5-methoxycarbonyl-1,2,3-triazole together with tetraacyl-D-ribofuranose, followed by deacylation, and its amide and hydrazide were prepared. The structures of the new nucleosides were established by converting them into known 2-nucleosides of 1,2,3-triazol-4-yl-carboxylic acid derivatives. By comparing PMR spectra with previously reported PMR spectra for the isomeric 1- and 2-nucleosides of 1,2,3-triazol-4-yl-carboxylic acid derivatives, the synthesized nucleosides could be assigned to 2-substituted triazoles.

  12. Chemical Logic and Enzymatic Machinery for Biological Assembly of Peptidyl Nucleoside Antibiotics

    PubMed Central

    Walsh, Christopher T.; Zhang, Wenjun

    2011-01-01

    Peptidyl nucleoside antibiotics are a group of natural products targeting MraY, a bacterial translocase involved in the lipid-linked cycle in peptidoglycan biosynthesis. In this Perspective, we explore how Nature builds complex peptidyl nucleoside antibiotics scaffolds from simple nucleoside and amino acid building blocks. We discuss the current stage of research on biosynthetic pathways for peptidyl nucleoside antibiotics, primarily focusing on chemical logic and enzymatic machinery for uridine transformation and coupling to peptides. We further survey the nonribosomal biosynthetic paradigm for a subgroup of uridyl peptide antibiotics represented by pacidamycins, concluded by diversification opportunities for antibiotic optimization. PMID:21851099

  13. Biological evaluation of a novel sorafenib analogue, t-CUPM.

    PubMed

    Wecksler, Aaron T; Hwang, Sung Hee; Liu, Jun-Yan; Wettersten, Hiromi I; Morisseau, Christophe; Wu, Jian; Weiss, Robert H; Hammock, Bruce D

    2015-01-01

    Sorafenib (Nexavar®) is currently the only FDA-approved small molecule targeted therapy for advanced hepatocellular carcinoma. The use of structural analogues and derivatives of sorafenib has enabled the elucidation of critical targets and mechanism(s) of cell death for human cancer lines. We previously performed a structure-activity relationship study on a series of sorafenib analogues designed to investigate the inhibition overlap between the major targets of sorafenib Raf-1 kinase and VEGFR-2, and an enzyme shown to be a potent off-target of sorafenib, soluble epoxide hydrolase. In the current work, we present the biological data on our lead sorafenib analogue, t-CUPM, demonstrating that this analogue retains cytotoxicity similar to sorafenib in various human cancer cell lines and strongly inhibits growth in the NCI-60 cell line panel. Co-treatment with the pan-caspase inhibitor, Z-VAD-FMK, failed to rescue the cell viability responses of both sorafenib and t-CUPM, and immunofluorescence microscopy shows similar mitochondrial depolarization and apoptosis-inducing factor release for both compounds. These data suggest that both compounds induce a similar mechanism of caspase-independent apoptosis in hepatoma cells. In addition, t-CUPM displays anti-proliferative effects comparable to sorafenib as seen by a halt in G0/G1 in cell cycle progression. The structural difference between sorafenib and t-CUPM significantly reduces inhibitory spectrum of kinases by this analogue, and pharmacokinetic characterization demonstrates a 20-fold better oral bioavailability of t-CUPM than sorafenib in mice. Thus, t-CUPM may have the potential to reduce the adverse events observed from the multikinase inhibitory properties and the large dosing regimens of sorafenib. PMID:25413440

  14. Conserved Glutamate Residues Glu-343 and Glu-519 Provide Mechanistic Insights into Cation/Nucleoside Cotransport by Human Concentrative Nucleoside Transporter hCNT3*

    PubMed Central

    Slugoski, Melissa D.; Smith, Kyla M.; Ng, Amy M. L.; Yao, Sylvia Y. M.; Karpinski, Edward; Cass, Carol E.; Baldwin, Stephen A.; Young, James D.

    2009-01-01

    Human concentrative nucleoside transporter 3 (hCNT3) utilizes electrochemical gradients of both Na+ and H+ to accumulate pyrimidine and purine nucleosides within cells. We have employed radioisotope flux and electrophysiological techniques in combination with site-directed mutagenesis and heterologous expression in Xenopus oocytes to identify two conserved pore-lining glutamate residues (Glu-343 and Glu-519) with essential roles in hCNT3 Na+/nucleoside and H+/nucleoside cotransport. Mutation of Glu-343 and Glu-519 to aspartate, glutamine, and cysteine severely compromised hCNT3 transport function, and changes included altered nucleoside and cation activation kinetics (all mutants), loss or impairment of H+ dependence (all mutants), shift in Na+:nucleoside stoichiometry from 2:1 to 1:1 (E519C), complete loss of catalytic activity (E519Q) and, similar to the corresponding mutant in Na+-specific hCNT1, uncoupled Na+ currents (E343Q). Consistent with close-proximity integration of cation/solute-binding sites within a common cation/permeant translocation pore, mutation of Glu-343 and Glu-519 also altered hCNT3 nucleoside transport selectivity. Both residues were accessible to the external medium and inhibited by p-chloromercuribenzene sulfonate when converted to cysteine. PMID:19380587

  15. Model Membrane and Cell Studies of Antimicrobial Activity of Melittin Analogues.

    PubMed

    Jamasbi, Elaheh; Mularski, Anna; Separovic, Frances

    2016-01-01

    Melittin is a 26 residue peptide and the major component of bee (Apis mellifera) venom. Although melittin has both anticancer and antimicrobial properties, utilization has been limited due to its high lytic activity against eukaryotic cells. The mechanism of this lytic activity remains unclear but several mechanisms have been proposed, including pore formation or a detergent like mechanism, which result in lysis of cell membranes. Several analogues of melittin have been synthesized to further understand the role of specific residues in its antimicrobial and lytic activity. Melittin analogues that have a proline residue substituted for an alanine, lysine or cysteine have been studied with both model membrane systems and living cells. These studies have revealed that the proline residue plays a critical role in antimicrobial activity and cytotoxicity. Analogues lacking the proline residue and dimers of these analogues displayed decreased cytotoxicity and minimum inhibition concentrations. Several mutant studies have shown that, when key substitutions are made, the resultant peptides have more activity in terms of pore formation than the native melittin. Designing analogues that retain antimicrobial and anticancer activity while minimizing haemolytic activity will be a promising way to utilize melittin as a potential therapeutic agent. PMID:26139117

  16. Design, Synthesis and Biological Evaluation of Tasiamide Analogues as Tumor Inhibitors

    PubMed Central

    Zhang, Wei; Sun, Tiantian; Ma, Zhenhua; Li, Yingxia

    2014-01-01

    Eighteen analogues of the marine cytotoxic linear peptide tasiamide were designed, synthesized and screened for their inhibitory activities against the growth of human nasopharyngeal carcinoma (KB) and human non-small cell lung tumor (A549) cell lines. The results indicated that minor modifications of the C-terminuswith aromatic groups were tolerated, with the IC50 values between 1.29 and 12.88 μM against these two cancer cell lines. Truncation, minor modifications at the N-terminus or elimination of the N-methyl groups in N-Me-d-Gln and/or N-Me-d-Phe residues resulted in inactive analogues. PMID:24759000

  17. Natural and semisynthetic analogues of manadoperoxide B reveal new structural requirements for trypanocidal activity.

    PubMed

    Chianese, Giuseppina; Scala, Fernando; Calcinai, Barbara; Cerrano, Carlo; Dien, Henny A; Kaiser, Marcel; Tasdemir, Deniz; Taglialatela-Scafati, Orazio

    2013-09-01

    Chemical analysis of the Indonesian sponge Plakortis cfr. lita afforded two new analogues of the potent trypanocidal agent manadoperoxide B (1), namely 12-isomanadoperoxide B (2) and manadoperoxidic acid B (3). These compounds were isolated along with a new short chain dicarboxylate monoester (4), bearing some interesting relationships with the polyketide endoperoxides found in this sponge. Some semi-synthetic analogues of manadoperoxide B (6-8) were prepared and evaluated for antitrypanosomal activity and cytotoxicity. These studies revealed crucial structure-activity relationships that should be taken into account in the design of optimized and simplified endoperoxyketal trypanocidal agents. PMID:23989650

  18. Synthesis of a simplified triazole analogue of pateamine A.

    PubMed

    Hemi Cumming, A; Brown, Sarah L; Tao, Xu; Cuyamendous, Claire; Field, Jessica J; Miller, John H; Harvey, Joanne E; Teesdale-Spittle, Paul H

    2016-06-14

    Pateamine A is a naturally occurring metabolite extracted from the marine sponge Mycale hentscheli. It exhibits potent cytotoxicity towards cancer cell lines and has been shown to target protein translation initiation via inhibition of the function of eukaryotic initiation factor 4A proteins. We have synthesised a simplified analogue of pateamine A, consisting of the skeletal core of the natural product but with the thiazole heterocycle replaced by a triazole. The convergent design of the synthesis features a base-induced opening of a δ-valerolactone to access the Z,E-dienoate moiety, Julia-Kocienski olefination and copper-catalysed azide-alkyne cycloaddition. Bioactivity testing of the simplified pateamine A analogue (3) indicated a significant reduction in cytotoxicity, compared to natural pateamine A. We propose that this reduced activity is due mainly to the substitution of the thiazole for the triazole heterocycle. This supports the hypothesis that the thiazole of pateamine A is important for binding to its biological target. PMID:27180995

  19. N-linked glycosylation of N48 is required for equilibrative nucleoside transporter 1 (ENT1) function.

    PubMed

    Bicket, Alex; Coe, Imogen R

    2016-08-01

    Human equilibrative nucleoside transporter 1 (hENT1) transports nucleosides and nucleoside analogue drugs across cellular membranes and is necessary for the uptake of many anti-cancer, anti-parasitic and anti-viral drugs. Previous work, and in silico prediction, suggest that hENT1 is glycosylated at Asn(48) in the first extracellular loop of the protein and that glycosylation plays a role in correct localization and function of hENT1. Site-directed mutagenesis of wild-type (wt) hENT1 removed potential glycosylation sites. Constructs (wt 3xFLAG-hENT1, N48Q-3xFLAG-hENT1 or N288Q-3xFLAG-hENT2) were transiently transfected into HEK293 cells and cell lysates were treated with or without peptide-N-glycosidase F (PNGase-F), followed by immunoblotting analysis. Substitution of N48 prevents hENT1 glycosylation, confirming a single N-linked glycosylation site. N48Q-hENT1 protein is found at the plasma membrane in HEK293 cells but at lower levels compared with wt hENT1 based on S-(4-nitrobenzyl)-6-thioinosine (NBTI) binding analysis (wt 3xFLAG-ENT1 Bmax, 41.5±2.9 pmol/mg protein; N48Q-3xFLAG-ENT1 Bmax, 13.5±0.45 pmol/mg protein) and immunofluorescence microscopy. Although present at the membrane, chloroadenosine transport assays suggest that N48Q-hENT1 is non-functional (wt 3xFLAG-ENT1, 170.80±44.01 pmol/mg protein; N48Q-3xFLAG-ENT1, 57.91±17.06 pmol/mg protein; mock-transfected 74.31±19.65 pmol/mg protein). Co-immunoprecipitation analyses suggest that N48Q ENT1 is unable to interact with self or with wt hENT1. Based on these data we propose that glycosylation at N48 is critical for the localization, function and oligomerization of hENT1. PMID:27480168

  20. N-linked glycosylation of N48 is required for equilibrative nucleoside transporter 1 (ENT1) function

    PubMed Central

    Bicket, Alex; Coe, Imogen R.

    2016-01-01

    Human equilibrative nucleoside transporter 1 (hENT1) transports nucleosides and nucleoside analogue drugs across cellular membranes and is necessary for the uptake of many anti-cancer, anti-parasitic and anti-viral drugs. Previous work, and in silico prediction, suggest that hENT1 is glycosylated at Asn48 in the first extracellular loop of the protein and that glycosylation plays a role in correct localization and function of hENT1. Site-directed mutagenesis of wild-type (wt) hENT1 removed potential glycosylation sites. Constructs (wt 3xFLAG-hENT1, N48Q-3xFLAG-hENT1 or N288Q-3xFLAG-hENT2) were transiently transfected into HEK293 cells and cell lysates were treated with or without peptide–N-glycosidase F (PNGase-F), followed by immunoblotting analysis. Substitution of N48 prevents hENT1 glycosylation, confirming a single N-linked glycosylation site. N48Q-hENT1 protein is found at the plasma membrane in HEK293 cells but at lower levels compared with wt hENT1 based on S-(4-nitrobenzyl)-6-thioinosine (NBTI) binding analysis (wt 3xFLAG-ENT1 Bmax, 41.5±2.9 pmol/mg protein; N48Q-3xFLAG-ENT1 Bmax, 13.5±0.45 pmol/mg protein) and immunofluorescence microscopy. Although present at the membrane, chloroadenosine transport assays suggest that N48Q-hENT1 is non-functional (wt 3xFLAG-ENT1, 170.80±44.01 pmol/mg protein; N48Q-3xFLAG-ENT1, 57.91±17.06 pmol/mg protein; mock-transfected 74.31±19.65 pmol/mg protein). Co-immunoprecipitation analyses suggest that N48Q ENT1 is unable to interact with self or with wt hENT1. Based on these data we propose that glycosylation at N48 is critical for the localization, function and oligomerization of hENT1. PMID:27480168

  1. Targeted enzyme prodrug therapy for metastatic prostate cancer – a comparative study of L-methioninase, purine nucleoside phosphorylase, and cytosine deaminase

    PubMed Central

    2014-01-01

    Background Enzyme prodrug therapy shows promise for the treatment of solid tumors, but current approaches lack effective/safe delivery strategies. To address this, we previously developed three enzyme-containing fusion proteins targeted via annexin V to phosphatidylserine exposed on the tumor vasculature and tumor cells, using the enzymes L-methioninase, purine nucleoside phosphorylase, or cytosine deaminase. In enzyme prodrug therapy, the fusion protein is allowed to bind to the tumor before a nontoxic drug precursor, a prodrug, is introduced. Upon interaction of the prodrug with the bound enzyme, an anticancer compound is formed, but only in the direct vicinity of the tumor, thereby mitigating the risk of side effects while creating high intratumoral drug concentrations. The applicability of these enzyme prodrug systems to treating prostate cancer has remained unexplored. Additionally, target availability may increase with the addition of low dose docetaxel treatment to the enzyme prodrug treatment, but this effect has not been previously investigated. To this end, we examined the binding strength and the cytotoxic efficacy (with and without docetaxel treatment) of these enzyme prodrug systems on the human prostate cancer cell line PC-3. Results All three fusion proteins exhibited strong binding; dissociation constants were 0.572 nM for L-methioninase-annexin V (MT-AV), 0.406 nM for purine nucleoside phosphorylase-annexin V (PNP-AV), and 0.061 nM for cytosine deaminase-annexin V (CD-AV). MT-AV produced up to 99% cell death (p < 0.001) with limited cytotoxicity of the prodrug alone. PNP-AV with docetaxel created up to 78% cell death (p < 0.001) with no cytotoxicity of the prodrug alone. CD-AV with docetaxel displayed up to 60% cell death (p < 0.001) with no cytotoxicity of the prodrug alone. Docetaxel treatment created significant increases in cytotoxicity for PNP-AV and CD-AV. Conclusions Strong binding of fusion proteins to the prostate cancer cells

  2. Isolation and structure elucidation of vicenistatin M, and importance of the vicenisamine aminosugar for exerting cytotoxicity of vicenistatin.

    PubMed

    Matsushima, Y; Nakayama, T; Fujita, M; Bhandari, R; Eguchi, T; Shindo, K; Kakinuma, K

    2001-03-01

    A new analogue of vicenistatin was isolated from the producing strain Streptomyces sp. HC-34. A characteristic of the elucidated structure involved the existence of a neutral sugar mycarose instead of an aminosugar vicenisamine of vicenistatin. The absolute stereochemistry of the new analogue (named as vicenistatin M) was determined by the synthesis of D-mycarose and of vicenistatin M itself. Biological testing of vicenistatin M suggested the importance of vicenisamine for exerting the cytotoxicity of vicenistatin. PMID:11372778

  3. Inhibition of ATP Synthase by Chlorinated Adenosine Analogue

    PubMed Central

    Chen, Lisa S.; Nowak, Billie J.; Ayres, Mary L.; Krett, Nancy L.; Rosen, Steven T.; Zhang, Shuxing; Gandhi, Varsha

    2009-01-01

    8-Chloroadenosine (8-Cl-Ado) is a ribonucleoside analogue that is currently in clinical trial for chronic lymphocytic leukemia. Based on the decline in cellular ATP pool following 8-Cl-Ado treatment, we hypothesized that 8-Cl-ADP and 8-Cl-ATP may interfere with ATP synthase, a key enzyme in ATP production. Mitochondrial ATP synthase is composed of two major parts; FO intermembrane base and F1 domain, containing α and β subunits. Crystal structures of both α and β subunits that bind to the substrate, ADP, are known in tight binding (αdpβdp) and loose binding (αtpβtp) states. Molecular docking demonstrated that 8-Cl-ADP/8-Cl-ATP occupied similar binding modes as ADP/ATP in the tight and loose binding sites of ATP synthase, respectively, suggesting that the chlorinated nucleotide metabolites may be functional substrates and inhibitors of the enzyme. The computational predictions were consistent with our whole cell biochemical results. Oligomycin, an established pharmacological inhibitor of ATP synthase, decreased both ATP and 8-Cl-ATP formation from exogenous substrates, however, did not affect pyrimidine nucleoside analogue triphosphate accumulation. Synthesis of ATP from ADP was inhibited in cells loaded with 8-Cl-ATP. These biochemical studies are in consent with the computational modeling; in the αtpβtp state 8-Cl-ATP occupies similar binding as ANP, a non-hydrolyzable ATP mimic that is a known inhibitor. Similarly, in the substrate binding site (αdpβdp) 8-Cl-ATP occupies a similar position as ATP mimic ADP-BeF3 −. Collectively, our current work suggests that 8-Cl-ADP may serve as a substrate and the 8-Cl-ATP may be an inhibitor of ATP synthase. PMID:19477165

  4. Synergistic enhancement of 5-fluorouracil cytotoxicity by deoxyuridine analogs in cancer cells

    PubMed Central

    Matsumoto, Yoshihiro; Rodriguez, Victoria; Whitford, Tracy A.; Beeharry, Neil; Ide, Hiroshi; Tomkinson, Alan E.

    2015-01-01

    5-Fluorouracil (FU) is a halogenated nucleobase analog that is widely used in chemotherapy. Here we show that 5-hydroxymethyl-2′-deoxyuridine (hmUdR) synergistically enhances the activity of FU in cell lines derived from solid tumors but not normal tissues. While the cytotoxicity of FU and hmUdR was not directly related to the amount of the modified bases incorporated into cellular DNA, incubation with this combination resulted in dramatic increase in the number of single strand breaks in replicating cancer cells, leading to NAD-depletion as consequence of poly(ADP-ribose) synthesis and S phase arrest. Cell death resulting from the base/nucleoside combination did not occur by apoptosis, autophagy or necroptosis. Instead, the cells die via necrosis as a result of NAD depletion. The FU-related nucleoside analog, 5-fluoro-2′-deoxyuridine, also displayed synergy with hmUdR, whereas hmUdR could not be replaced by 5-hydroxymethyluracil. Among other 5-modified deoxyuridine analogs tested, 5-formyl-2′-deoxyuridine and, to a lesser extent, 5-hydroxy-2′-deoxyuridine, also acted synergistically with FU, whereas 5-hydroxyethyl-2′-deoxyuridine did not. Together, our results have revealed an unexpected synergistic interaction between deoxyuridine analogs and FU in a cancer cell-specific manner, and suggest that these novel base/nucleoside combinations could be developed into improved FU-based chemotherapies. PMID:25897430

  5. Regulation by equilibrative nucleoside transporter of adenosine outward currents in adult rat spinal dorsal horn neurons.

    PubMed

    Liu, Tao; Fujita, Tsugumi; Kawasaki, Yasuhiko; Kumamoto, Eiichi

    2004-07-30

    A current response induced by superfusing adenosine was examined in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. In 78% of the neurons examined, adenosine induced an outward current at -70 mV [18.8 +/- 1.1 pA (n = 98) at 1mM] in a dose-dependent manner (EC(50) = 177 microM). A similar current was induced by A(1) agonist N(6)-cyclopentyladenosine (1 microM), whereas A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (1 microM) reversed the adenosine action. The adenosine current reversed its polarity at a potential being close to the equilibrium potential for K(+), and was attenuated by Ba(2+) (100 microM) and 4-aminopyridine (5mM) but not tetraethylammonium (5mM). The adenosine current was enhanced in duration by equilibrative nucleoside-transport (rENT1) inhibitor S-(4-nitrobenzyl)-6-thioinosine (1 microM) and adenosine deaminase (ADA) inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (1 microM), and slowed in falling phase by adenosine kinase (AK) inhibitor iodotubercidine (1 microM). We conclude that a Ba(2+)- and 4-aminopyridine-sensitive K(+) channel in SG neurons is opened via the activation of A(1) receptors by adenosine whose level is possibly regulated by rENT1, adenosine deaminase and adenosine kinase. Considering that intrathecally-administered adenosine analogues produce antinociception, the regulatory systems of adenosine may serve as targets for antinociceptive drugs. PMID:15275960

  6. O2 Protonation Controls Threshold Behavior for N-Glycosidic Bond Cleavage of Protonated Cytosine Nucleosides.

    PubMed

    Wu, R R; Rodgers, M T

    2016-06-01

    IRMPD action spectroscopy studies of protonated 2'-deoxycytidine and cytidine, [dCyd+H](+) and [Cyd+H](+), have established that both N3 and O2 protonated conformers coexist in the gas phase. Threshold collision-induced dissociation (CID) of [dCyd+H](+) and [Cyd+H](+) is investigated here using guided ion beam tandem mass spectrometry techniques to elucidate the mechanisms and energetics for N-glycosidic bond cleavage. N-Glycosidic bond cleavage is observed as the major dissociation pathways resulting in competitive elimination of either protonated or neutral cytosine for both protonated cytosine nucleosides. Electronic structure calculations are performed to map the potential energy surfaces (PESs) for both N-glycosidic bond cleavage pathways observed. The molecular parameters derived from theoretical calculations are employed for thermochemical analysis of the energy-dependent CID data to determine the minimum energies required to cleave the N-glycosidic bond along each pathway. B3LYP and MP2(full) computed activation energies for N-glycosidic bond cleavage associated with elimination of protonated and neutral cytosine, respectively, are compared to measured values to evaluate the efficacy of these theoretical methods in describing the dissociation mechanisms and PESs for N-glycosidic bond cleavage. The 2'-hydroxyl of [Cyd+H](+) is found to enhance the stability of the N-glycosidic bond vs that of [dCyd+H](+). O2 protonation is found to control the threshold energies for N-glycosidic bond cleavage as loss of neutral cytosine from the O2 protonated conformers is found to require ∼25 kJ/mol less energy than the N3 protonated analogues, and the activation energies and reaction enthalpies computed using B3LYP exhibit excellent agreement with the measured thresholds for the O2 protonated conformers. PMID:27159774

  7. Neighboring Group Participation in the Transition State of Human Purine Nucleoside Phosphorylase

    SciTech Connect

    Murkin,A.; Birck, M.; Rinaldo-Matthis, A.; Shi, W.; Taylor, E.; Almo, S.; Schramm, V.

    2007-01-01

    The X-ray crystal structures of human purine nucleoside phosphorylase (PNP) with bound inosine or transition-state analogues show His{sup 257} within hydrogen bonding distance of the 5'-hydroxyl. The mutants His257Phe, His257Gly, and His257Asp exhibited greatly decreased affinity for Immucillin-H (ImmH), binding this mimic of an early transition state as much as 370-fold (K{sub m}/K{sub i}) less tightly than native PNP. In contrast, these mutants bound DADMe-ImmH, a mimic of a late transition state, nearly as well as the native enzyme. These results indicate that His{sup 257} serves an important role in the early stages of transition-state formation. Whereas mutation of His{sup 257} resulted in little variation in the PNP{center_dot}DADMe-ImmH{center_dot}SO{sub 4} structures, His257Phe{center_dot}ImmH{center_dot}PO{sub 4} showed distortion at the 5'-hydroxyl, indicating the importance of H-bonding in positioning this group during progression to the transition state. Binding isotope effect (BIE) and kinetic isotope effect (KIE) studies of the remote 5'-{sup 3}H for the arsenolysis of inosine with native PNP revealed a BIE of 1.5% and an unexpectedly large intrinsic KIE of 4.6%. This result is interpreted as a moderate electronic distortion toward the transition state in the Michaelis complex with continued development of a similar distortion at the transition state. The mutants His257Phe, His257Gly, and His257Asp altered the 5'-{sup 3}H intrinsic KIE to -3, -14, and 7%, respectively, while the BIEs contributed 2, 2, and -2%, respectively. These surprising results establish that forces in the Michaelis complex, reported by the BIEs, can be reversed or enhanced at the transition state.

  8. Origin, Utilization, and Recycling of Nucleosides in the Central Nervous System

    ERIC Educational Resources Information Center

    Ipata, Piero Luigi

    2011-01-01

    The brain relies on the salvage of preformed purine and pyrimidine rings, mainly in the form of nucleosides, to maintain its nucleotide pool in the proper qualitative and quantitative balance. The transport of nucleosides from blood into neurons and glia is considered to be an essential prerequisite to enter their metabolic utilization in the…

  9. Analysis of Nucleosides in Municipal Wastewater by Large-Volume Liquid Chromatography Tandem Mass Spectrometry

    PubMed Central

    Brewer, Alex J.; Lunte, Craig

    2015-01-01

    Nucleosides are components of both DNA and RNA, and contain either a ribose (RNA) or 2deoxyribose (DNA) sugar and a purine or pyrimidine base. In addition to DNA and RNA turnover, modified nucleosides found in urine have been correlated to a diminished health status associated with AIDS, cancers, oxidative stress and age. Nucleosides found in municipal wastewater influent are potentially useful markers of community health status, and as of now, remain uninvestigated. A method was developed to quantify nucleosides in municipal wastewater using large-volume injection, liquid chromatography, and mass spectrometry. Method accuracy ranged from 92 to 139% when quantified by using isotopically labeled internal standards. Precision ranged from 6.1 to 19% of the relative standard deviation. The method’s utility was demonstrated by the analysis of twenty-four hour composite wastewater influent samples that were collected over a week to investigate community nucleoside excretion. Nucleosides originating from RNA were more abundant that DNA over the study period, with total loads of nucleosides ranging from 2 to 25 kg/day. Given this relatively high amount of nucleosides found over the study period they present an attractive analyte for the investigation of community health. PMID:26322136

  10. Synthesis of carbocyclic nucleoside analogs with five-membered heterocyclic nucleobases

    PubMed Central

    Cho, Jong hyun; Coats, Steven J.; Schinazi, Raymond F.

    2015-01-01

    New carbocyclic nucleoside analogs with five-membered heterocyclic nucleobases were synthesized and evaluated as potential anti-HIV and anti-HCV agents. Among the synthesized carbocyclic nucleoside analogs, the pyrazole amide 15f exhibited modest selective anti-HIV-1 activity (EC50 = 24 µM). PMID:26028788

  11. Visualizing nucleic acid metabolism using non-natural nucleosides and nucleotide analogs.

    PubMed

    Choi, Jung-Suk; Berdis, Anthony J

    2016-01-01

    Nucleosides and their corresponding mono-, di-, and triphosphates play important roles in maintaining cellular homeostasis. In addition, perturbations in this homeostasis can result in dysfunctional cellular processes that cause pathological conditions such as cancer and autoimmune diseases. This review article discusses contemporary research areas applying nucleoside analogs to probe the mechanistic details underlying the complexities of nucleoside metabolism at the molecular and cellular levels. The first area describes classic and contemporary approaches used to quantify the activity of nucleoside transporters, an important class of membrane proteins that mediate the influx and efflux of nucleosides and nucleobases. A focal point of this section is describing how biophotonic nucleosides are replacing conventional assays employing radiolabeled substrates to study the mechanism of these proteins. The second section describes approaches to understand the utilization of nucleoside triphosphates by cellular DNA polymerases during DNA synthesis. Emphasis here is placed on describing how novel nucleoside analogs such as 5-ethynyl-2'-deoxyuridine are being used to quantify DNA synthesis during normal replication as well as during the replication of damaged DNA. In both sections, seminal research articles relevant to these areas are described to highlight how these novel probes are improving our understanding of these biological processes. This article is part of a Special Issue entitled: Physiological Enzymology and Protein Functions. PMID:26004088

  12. A procedure for the preparation and isolation of nucleoside-5’-diphosphates

    PubMed Central

    Korhonen, Heidi J; Bolt, Hannah L

    2015-01-01

    Summary Tris[bis(triphenylphosphoranylidene)ammonium] pyrophosphate (PPN pyrophosphate) was used in the SN2 displacements of the tosylate ion from 5’-tosylnucleosides to afford nucleoside-5’-diphosphates. Selective precipitation permitted the direct isolation of nucleoside-5’-diphosphates from crude reaction mixtures. PMID:25977720

  13. Comparative cytotoxicity of gambierol versus other marine neurotoxins.

    PubMed

    Cagide, E; Louzao, M C; Espiña, B; Ares, I R; Vieytes, M R; Sasaki, M; Fuwa, H; Tsukano, C; Konno, Y; Yotsu-Yamashita, M; Paquette, L A; Yasumoto, T; Botana, L M

    2011-06-20

    Many microalgae produce compounds that exhibit potent biological activities. Ingestion of marine organisms contaminated with those toxins results in seafood poisonings. In many cases, the lack of toxic material turns out to be an obstacle to make the toxicological investigations needed. In this study, we evaluate the cytotoxicity of several marine toxins on neuroblastoma cells, focusing on gambierol and its effect on cytosolic calcium levels. In addition, we compared the effects of this toxin with ciguatoxin, brevetoxin, and gymnocin-A, with which gambierol shares a similar ladder-like backbone, as well as with polycavernoside A analogue 5, a glycosidic macrolide toxin. For this purpose, different fluorescent dyes were used: Fura-2 to monitor variations in cytosolic calcium levels, Alamar Blue to detect cytotoxicity, and Oregon Green 514 Phalloidin to quantify and visualize modifications in the actin cytoskeleton. Data showed that, while gambierol and ciguatoxin were successful in producing a calcium influx in neuroblastoma cells, gymnocin-A was unable to modify this parameter. Nevertheless, none of the toxins induced morphological changes or alterations in the actin assembly. Although polycavernoside A analogue 5 evoked a sharp reduction of the cellular metabolism of neuroblastoma cells, gambierol scarcely reduced it, and ciguatoxin, brevetoxin, and gymnocin-A failed to produce any signs of cytotoxicity. According to this, sharing a similar polycyclic ether backbone is not enough to produce the same effects on neuroblastoma cells; therefore, more studies should be carried out with these toxins, whose effects may be being underestimated. PMID:21517028

  14. Binding of nucleotides to nucleoside diphosphate kinase: a calorimetric study.

    PubMed

    Cervoni, L; Lascu, I; Xu, Y; Gonin, P; Morr, M; Merouani, M; Janin, J; Giartosio, A

    2001-04-17

    The source of affinity for substrates of human nucleoside diphosphate (NDP) kinases is particularly important in that its knowledge could be used to design more effective antiviral nucleoside drugs (e.g., AZT). We carried out a microcalorimetric study of the binding of enzymes from two organisms to various nucleotides. Isothermal titration calorimetry has been used to characterize the binding in terms of Delta G degrees, Delta H degrees and Delta S degrees. Thermodynamic parameters of the interaction of ADP with the hexameric NDP kinase from Dictyostelium discoideum and with the tetrameric enzyme from Myxococcus xanthus, at 20 degrees C, were similar and, in both cases, binding was enthalpy-driven. The interactions of ADP, 2'deoxyADP, GDP, and IDP with the eukaryotic enzyme differed in enthalpic and entropic terms, whereas the Delta G degrees values obtained were similar due to enthalpy--entropy compensation. The binding of the enzyme to nonphysiological nucleotides, such as AMP--PNP, 3'deoxyADP, and 3'-deoxy-3'-amino-ADP, appears to differ in several respects. Crystallography of the protein bound to 3'-deoxy-3'-amino-ADP showed that the drug was in a distorted position, and was unable to interact correctly with active site side chains. The interaction of pyrimidine nucleoside diphosphates with the hexameric enzyme is characterized by a lower affinity than that with purine nucleotides. Titration showed the stoichiometry of the interaction to be abnormal, with 9--12 binding sites/hexamer. The presence of supplementary binding sites might have physiological implications. PMID:11294625

  15. Phosphonomethyl analogues of hexose phosphates.

    PubMed

    Webster, D; Jondorf, W R; Dixon, H B

    1976-05-01

    The analogue of fructose 1,6-bisphosphate in which the phosphate group, -O-PO3H2, on C-6 is replaced by the phosphonomethyl group, -CH2-PO3H2, was made enzymically from the corresponding analogue of 3-phosphoglycerate. It was a substrate for aldolase, which was used to form it, but not for fructose 1,6-bisphosphatase. It was hydrolysed chemically to yield the corresponding analogue of fructose 6-phosphate [i.e. 6-deoxy-6-(phosphonomethyl)-D-fructose, or, more strictly, 6,7-dideoxy-7-phosphono-D-arabino-2-heptulose]. This proved to be a substrate for the sequential actions of glucose 6-phosphate isomerase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Thus seven out of the nine enzymes of the glycolytic and pentose phosphate pathways so far tested catalyse the reactions of the phosphonomethyl isosteres of their substrates. PMID:7247

  16. Computer-generated Model of Purine Nucleoside Phosphorylase (PNP)

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Purine Nucleoside Phosphorylase (PNP) is an important target enzyme for the design of anti-cancer and immunosuppressive drugs. Bacterial PNP, which is slightly different from the human enzyme, is used to synthesize chemotherapuautic agents. Knowledge of the three-dimensional structure of the bacterial PNP molecule is useful in efforts to engineer different types of PNP enzymes, that can be used to produce new chemotherapeutic agents. This picture shows a computer model of bacterial PNP, which looks a lot like a display of colorful ribbons. Principal Investigator was Charles Bugg.

  17. Oligodeoxyribonucleotides containing 1,3-propanediol as nucleoside substitute.

    PubMed Central

    Seela, F; Kaiser, K

    1987-01-01

    1,3-Propanediol was protected with one dimethoxytrityl residue and converted into the methoxy- and cyanoethoxyphosphoramidites 2a and 2b, respectively. Solid-phase oligonucleotide synthesis, employing the phosphoramidite 2a resulted in the dodecamers d(CGCGAATTCGCG) (6-9), in which dA or dT residues were replaced by 1,3-propanediol. These oligomers showed a high tendency to form hairpins. Their phosphodiester bonds between the 3'-position of a nucleoside and the propanediol moiety was not cleaved by snake venom phosphodiesterase. PMID:3562246

  18. Synthesis of 5-Fluoroalkylated Pyrimidine Nucleosides via Negishi Cross-Coupling

    PubMed Central

    Chacko, Ann-Marie; Qu, Wenchao

    2014-01-01

    5-fluoroalkylated pyrimidine nucleosides (1) have potential as therapeutic agents and molecular imaging agents targeting HSV1-tk suicide gene therapy. Thus, straightforward preparation of 5-fluoroalkylated nucleoside derivatives has been developed. Reported herein are the first examples of Pd-catalyzed Negishi cross-coupling of 3-N-benzoyl-3′,5′-di-O-benzoyl-5-iodo-2′-deoxyuridine (2a) and 3-N-benzoyl-3′,5′-di-O-benzoyl-5-iodo-2′-deoxy-2′-fluoroarabinouridine (2b) with unactivated Csp3 fluoroalkylzinc bromides. This paper demonstrates the first synthesis of six 5-fluoroalkyl-2′-deoxy pyrimidine nucleoside derivatives with three to five methylene-chain lengths (5). Furthermore, this methodology has been extended to create a series of thirteen 5-alkyl substituted nucleosides, including the target nucleosides 5 and 5-silyloxypropyl and 5-cyanobutyl derivatives. PMID:18522415

  19. Theoretical understanding of two-photon-induced fluorescence of isomorphic nucleoside analogs.

    PubMed

    Samanta, Pralok K; Pati, Swapan K

    2015-04-21

    We use ab initio Density Functional Theory (DFT) and Time-dependent DFT (TDDFT) calculations for a detailed understanding of one-photon absorption (1PA) and two-photon absorption (2PA) cross sections of eight different nucleoside analogs. The results are compared and contrasted with the available experimental data. Our calculated results show that the low energy peaks in the absorption spectra mainly arise because of the π-π* electronic transition of the nucleoside analogs. The emission spectra of the nucleoside analogs are also calculated using TDDFT methods. The calculated absorption and emission spectra in the presence of a solvent follow the same trend as those found experimentally. Our results demonstrate that the nucleoside analogs show significantly different electronic and optical properties, although their bonding aspects towards Watson-Crick base pairing remain the same. We also derive the microscopic details of the origin of nonlinear optical properties of the nucleoside analogs. PMID:25785569

  20. A high-yielding, strictly regioselective prebiotic purine nucleoside formation pathway.

    PubMed

    Becker, Sidney; Thoma, Ines; Deutsch, Amrei; Gehrke, Tim; Mayer, Peter; Zipse, Hendrik; Carell, Thomas

    2016-05-13

    The origin of life is believed to have started with prebiotic molecules reacting along unidentified pathways to produce key molecules such as nucleosides. To date, a single prebiotic pathway to purine nucleosides had been proposed. It is considered to be inefficient due to missing regioselectivity and low yields. We report that the condensation of formamidopyrimidines (FaPys) with sugars provides the natural N-9 nucleosides with extreme regioselectivity and in good yields (60%). The FaPys are available from formic acid and aminopyrimidines, which are in turn available from prebiotic molecules that were also detected during the Rosetta comet mission. This nucleoside formation pathway can be fused to sugar-forming reactions to produce pentosides, providing a plausible scenario of how purine nucleosides may have formed under prebiotic conditions. PMID:27174989

  1. Synthesis and structure-activity relationship of vicenistatin, a cytotoxic 20-membered macrolactam glycoside.

    PubMed

    Fukuda, Hayato; Nishiyama, Yuko; Nakamura, Shiina; Ohno, Yutaro; Eguchi, Tadashi; Iwabuchi, Yoshiharu; Usui, Takeo; Kanoh, Naoki

    2012-12-01

    We have developed two syntheses of vicenistatin and its analogues. Our first-generation strategy included the rapid and sequential assembly of the macrocyclic lactam by using an intermolecular Horner-Wadsworth-Emmons reaction between the C3-C13 fragment and the C1-C2, C14-C19 fragment, followed by an intramolecular Stille coupling reaction. The second-generation strategy utilized a ring-closing metathesis of a hexaene intermediate to generate the desired 20-membered macrolactam. This second-generation strategy made it possible to prepare synthetic analogues of vicenistatin, including the C20- and/or C23-demethyl analogues. Evaluation of the cytotoxic effect of these analogues indicated the importance of the fixed conformation of aglycon for determining the biological activity of the vicenistatins. PMID:23015368

  2. Na+ reabsorption in cultured rat epididymal epithelium via the Na+/nucleoside cotransporter.

    PubMed

    Leung, G P; Cheung, K H; Tse, C M; Wong, P Y

    2001-03-01

    The effect of nucleoside on Na+ reabsorption via Na+/nucleoside cotransporter in cultured rat epididymal epithelia was studied by short-circuit current (Isc) technique. Guanosine added apically stimulated Isc in a dose-dependent manner, with a median effective concentration (EC50) of 7 +/- 2 microM (mean +/- SEM). Removal of Na+ from the apical bathing solution or pretreatment with a nonspecific Na+/nucleoside cotransporter inhibitor, phloridzin, completely blocked the Isc response to guanosine. Moreover, the guanosine response was abolished by pretreatment of the tissue with ouabain, a Na+/K+-ATPase inhibitor, suggesting the involvement of Na+/nucleoside cotransporter on the apical side and Na+/K+-ATPase on the basolateral side in Na+ reabsorption. In contrast, the Isc response to guanosine was not affected after desensitization of purinoceptors by ATP. Addition of the Na+/K+/2Cl- symport inhibitor bumetanide to the basolateral side or the nonspecific Cl- channel blocker diphenylamine-2-carboxylate to the apical side showed no effect on the Isc response to guanosine, excluding stimulation of Cl- secretion by guanosine as the cause of the guanosine-induced Isc. The Isc response to purine nucleoside (guanosine and inosine) was much higher than that to pyrimidine nucleoside (thymidine and cytidine). Consistent with substrate specificity, results of reverse transcription-polymerase chain reaction revealed mRNA for concentrative nucleoside transporter (CNT2), which is a purine nucleoside-selective Na+/nucleoside cotransporter in the epididymis, but not for CNT1. It is suggested that the Na+/nucleoside cotransporter (i.e., CNT2) may be one of the elements involved in Na+ and fluid reabsorption in the epididymis, thereby providing an optimal microenvironment for the maturation and storage of spermatozoa. PMID:11207189

  3. Bisphenol Analogues Other Than BPA: Environmental Occurrence, Human Exposure, and Toxicity-A Review.

    PubMed

    Chen, Da; Kannan, Kurunthachalam; Tan, Hongli; Zheng, Zhengui; Feng, Yong-Lai; Wu, Yan; Widelka, Margaret

    2016-06-01

    Numerous studies have investigated the environmental occurrence, human exposure, and toxicity of bisphenol A (BPA). Following stringent regulations on the production and usage of BPA, several bisphenol analogues have been produced as a replacement for BPA in various applications. The present review outlines the current state of knowledge on the occurrence of bisphenol analogues (other than BPA) in the environment, consumer products and foodstuffs, human exposure and biomonitoring, and toxicity. Whereas BPA was still the major bisphenol analogue found in most environmental monitoring studies, BPF and BPS were also frequently detected. Elevated concentrations of BPAF, BPF, and BPS (i.e., similar to or greater than that of BPA) have been reported in the abiotic environment and human urine from some regions. Many analogues exhibit endocrine disrupting effects, cytotoxicity, genotoxicity, reproductive toxicity, dioxin-like effects, and neurotoxicity in laboratory studies. BPAF, BPB, BPF, and BPS have been shown to exhibit estrogenic and/or antiandrogenic activities similar to or even greater than that of BPA. Knowledge gaps and research needs have been identified, which include the elucidation of environmental occurrences, persistence, and fate of bisphenol analogues (other than BPA), sources and pathways for human exposure, effects on reproductive systems and the mammary gland, mechanisms of toxicity from coexposure to multiple analogues, metabolic pathways and products, and the impact of metabolic modification on toxicity. PMID:27143250

  4. Adenosine kinase inhibitors. 1. Synthesis, enzyme inhibition, and antiseizure activity of 5-iodotubercidin analogues.

    PubMed

    Ugarkar, B G; DaRe, J M; Kopcho, J J; Browne, C E; Schanzer, J M; Wiesner, J B; Erion, M D

    2000-07-27

    Adenosine receptor agonists produce a wide variety of therapeutically useful pharmacologies. However, to date they have failed to undergo successful clinical development due to dose-limiting side effects. Adenosine kinase inhibitors (AKIs) represent an alternative strategy, since AKIs may raise local adenosine levels in a more site- and event-specific manner and thereby elicit the desired pharmacology with a greater therapeutic window. Starting with 5-iodotubercidin (IC50 = 0.026 microM) and 5'-amino-5'-deoxyadenosine (IC50 = 0.17 microM) as lead inhibitors of the isolated human AK, a variety of pyrrolo[2,3-d]pyrimidine nucleoside analogues were designed and prepared by coupling 5-substituted-4-chloropyrrolo[2,3-d]pyrimidine bases with ribose analogues using the sodium salt-mediated glycosylation procedure. 5'-Amino-5'-deoxy analogues of 5-bromo- and 5-iodotubercidins were found to be the most potent AKIs reported to date (IC50S < 0.001 microM). Several potent AKIs were shown to exhibit anticonvulsant activity in the rat maximal electric shock (MES) induced seizure assay. PMID:10956196

  5. Discovery of the Aryl-phospho-indole IDX899, a Highly Potent Anti-HIV Non-nucleoside Reverse Transcriptase Inhibitor.

    PubMed

    Dousson, Cyril; Alexandre, François-René; Amador, Agnès; Bonaric, Séverine; Bot, Stéphanie; Caillet, Catherine; Convard, Thierry; da Costa, Daniel; Lioure, Marie-Pierre; Roland, Arlène; Rosinovsky, Elodie; Maldonado, Sébastien; Parsy, Christophe; Trochet, Christophe; Storer, Richard; Stewart, Alistair; Wang, Jingyang; Mayes, Benjamin A; Musiu, Chiara; Poddesu, Barbara; Vargiu, Luana; Liuzzi, Michel; Moussa, Adel; Jakubik, Jocelyn; Hubbard, Luke; Seifer, Maria; Standring, David

    2016-03-10

    Here, we describe the design, synthesis, biological evaluation, and identification of a clinical candidate non-nucleoside reverse transcriptase inhibitors (NNRTIs) with a novel aryl-phospho-indole (APhI) scaffold. NNRTIs are recommended components of highly active antiretroviral therapy (HAART) for the treatment of HIV-1. Since a major problem associated with NNRTI treatment is the emergence of drug resistant virus, this work focused on optimization of the APhI against clinically relevant HIV-1 Y181C and K103N mutants and the Y181C/K103N double mutant. Optimization of the phosphinate aryl substituent led to the discovery of the 3-Me,5-acrylonitrile-phenyl analogue RP-13s (IDX899) having an EC50 of 11 nM against the Y181C/K103N double mutant. PMID:26804933

  6. Involvement of concentrative nucleoside transporter 1 in intestinal absorption of trifluorothymidine, a novel antitumor nucleoside, in rats.

    PubMed

    Okayama, Takashige; Yoshisue, Kunihiro; Kuwata, Keizo; Komuro, Masahito; Ohta, Shigeru; Nagayama, Sekio

    2012-02-01

    ααα-Trifluorothymidine (TFT), an anticancer nucleoside analog, is a potent thymidylate synthase inhibitor. TFT exerts its antitumor activity primarily by inducing DNA fragmentation after incorporation of the triphosphate form of TFT into the DNA. Although an oral combination of TFT and a thymidine phosphorylase inhibitor has been clinically developed, there is little information regarding TFT absorption. Therefore, we investigated TFT absorption in the rat small intestine. After oral administration of TFT in rats, more than 75% of the TFT was absorbed. To identify the uptake transport system, uptake studies were conducted by using everted sacs prepared from rat small intestines. TFT uptake was saturable, significantly reduced under Na(+)-free conditions, and strongly inhibited by the addition of an endogenous pyrimidine nucleoside. From these results, we suggested the involvement of concentrative nucleoside transporters (CNTs) in TFT absorption into rat small intestine. In rat small intestines, the mRNAs coding for rat CNT1 (rCNT1) and rCNT2, but not for rCNT3, were predominantly expressed. To investigate the roles of rCNT1 and rCNT2 in TFT uptake, we conducted uptake assays by using Xenopus laevis oocytes injected with rCNT1 complementary RNA (cRNA) and rCNT2 cRNA. TFT uptake by X. laevis oocytes injected with rCNT1 cRNA, and not rCNT2 cRNA, was significantly greater than that by water-injected oocytes. In addition, in situ single-pass perfusion experiments performed using rat jejunum regions showed that thymidine, a substrate for CNT1, strongly inhibited TFT uptake. In conclusion, TFT is absorbed via rCNT1 in the intestinal lumen in rats. PMID:22076553

  7. Synthesis of 7 alpha- and 7 beta-spermidinylcholesterol, squalamine analogues.

    PubMed

    Choucair, B; Dherbomez, M; Roussakis, C; El-kihel, L

    2004-08-16

    Stereoselective synthesis of squalamine dessulfates analogues, 7 alpha and 7 beta-N-[3N-(4-aminobutyl) aminopropyl]aminocholesterol are reported, using 7 alpha and 7 beta-aminocholesterol as a key intermediate. It's the first example in which the position of spermidine is modified at the steroid ring. These molecules showed a comparable antibacteria and fungi activities to squalamine. Then, they have a cytotoxic activity on a human non-small cell bronchopulmonary carcinoma line (NSCLC-N6). PMID:15261272

  8. Determination of Cytotoxicity.

    PubMed

    2016-01-01

    Cytotoxicity assays are used for drug screening and cytotoxicity tests of chemicals. Nowadays, various reagents are used for cell viability detection. They are based on various cell functions such as enzyme activity, cell membrane permeability, cell adherence, ATP production, co-enzyme production and nucleotide uptake activity. Many have established methods such as colony formation method, crystal violet method, tritium-labelled thymidine uptake method, MTT and WST methods, which are used for counting the number of live cells. Moreover, trypan blue is a widely used assay for staining dead cells. In this method, cell viability must be determined by counting the unstained cells with a microscope or other instruments. This chapter is a collection of all these methods to be followed by researchers in a sequential manner. PMID:26939283

  9. Cytotoxicity of Vinca minor.

    PubMed

    Khanavi, Mahnaz; Pourmoslemi, Shabnam; Farahanikia, Behnaz; Hadjiakhoondi, Abbas; Ostad, Seyed Nasser

    2010-01-01

    Vinca minor L. (Apocynaceae) is a medicinal plant that has long been used to treat cerebral and memory disorders in European folk medicine. Furthermore, it contains more than 50 alkaloids, some of them having bisindole structure such as the antineoplastic alkaloids present in Catharanthus roseus (L.) G. Don (Apocynaceae). In this study, the plant's alkaloid extract was divided into three fractions and the cytotoxic effects on cell proliferation of HT-29, Caco-2, T47D, and NIH/3T3 cell lines were examined. All alkaloid fractions showed a dose-dependent cytotoxic effect on the cell lines. IC(50) values confirmed that the growth and proliferation of NIH/3T3 cells were less affected in comparison to other cell lines. PMID:20645762

  10. Fluorinated Nanocarbons Cytotoxicity.

    PubMed

    Teo, Wei Zhe; Chua, Chun Kiang; Sofer, Zdenek; Pumera, Martin

    2015-09-01

    As the research in nanotechnology progresses, there will eventually be an influx in the number of commercial products containing different types of nanomaterials. This phenomenon might damage our health and environment if the nanomaterials used are found to be toxic and they are released into the waters when the products degrade. In this study, we investigated the cytotoxicity of fluorinated nanocarbons (CXFs), a group of nanomaterials which can find applications in solid lubricants and lithium primary batteries. Our cell viability findings indicated that the toxicological effects induced by the CXF are dependent on the dose, size, shape, and fluorine content of the CXF. In addition, we verified that CXFs have insignificant interactions with the cell viability assays-methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8), thus suggesting that the cytotoxicity data obtained are unlikely to be affected by CXF-induced artifacts and the results will be reliable. PMID:26215131

  11. Kinetic and biochemical characterization of Trypanosoma evansi nucleoside triphosphate diphosphohydrolase.

    PubMed

    Weiss, Paulo Henrique Exterchoter; Batista, Franciane; Wagner, Glauber; Magalhães, Maria de Lourdes Borba; Miletti, Luiz Claudio

    2015-06-01

    Nucleoside triphosphate diphospho-hydrolases (NTPDases) catalyze the hydrolysis of several nucleosides tri and diphosphate playing major roles in eukaryotes including purinergic signaling, inflammation, hemostasis, purine salvage and host-pathogen interactions. These enzymes have been recently described in parasites where several evidences indicated their involvement in virulence and infection. Here, we have investigated the presence of NTPDase in the genome of Trypanosoma evansi. Based on the genomic sequence from Trypanosoma brucei, we have amplified an 1812 gene fragment corresponding to the T. evansi NTPDase gene. The protein was expressed in the soluble form and purified to homogeneity and enzymatic assays were performed confirming the enzyme identity. Kinetic parameters and substrate specificity were determined. The dependence of cations on enzymatic activity was investigated indicating the enzyme is stimulated by divalent cations and carbohydrates but inhibited by sodium. Bioinformatic analysis indicates the enzyme is a membrane bound protein facing the extracellular side of the cell with 98% identity to the T. brucei homologous NTPDase gene. PMID:25819299

  12. Adenylate kinase complements nucleoside diphosphate kinase deficiency in nucleotide metabolism.

    PubMed Central

    Lu, Q; Inouye, M

    1996-01-01

    Nucleoside diphosphate (NDP) kinase is a ubiquitous nonspecific enzyme that evidently is designed to catalyze in vivo ATP-dependent synthesis of ribo- and deoxyribonucleoside triphosphates from the corresponding diphosphates. Because Escherichia coli contains only one copy of ndk, the structural gene for this enzyme, we were surprised to find that ndk disruption yields bacteria that are still viable. These mutant cells contain a protein with a small amount NDP kinase activity. The protein responsible for this activity was purified and identified as adenylate kinase. This enzyme, also called myokinase, catalyzes the reversible ATP-dependent synthesis of ADP from AMP. We found that this enzyme from E. coli as well as from higher eukaryotes has a broad substrate specificity displaying dual enzymatic functions. Among the nucleoside monophosphate kinases tested, only adenylate kinase was found to have NDP kinase activity. To our knowledge, this is the first report of NDP kinase activity associated with adenylate kinase. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:8650159

  13. Lethal Mutagenesis of HIV with Mutagenic Nucleoside Analogs

    NASA Astrophysics Data System (ADS)

    Loeb, Lawrence A.; Essigmann, John M.; Kazazi, Farhad; Zhang, Jue; Rose, Karl D.; Mullins, James I.

    1999-02-01

    The human immunodeficiency virus (HIV) replicates its genome and mutates at exceptionally high rates. As a result, the virus is able to evade immunological and chemical antiviral agents. We tested the hypothesis that a further increase in the mutation rate by promutagenic nucleoside analogs would abolish viral replication. We evaluated deoxynucleoside analogs for lack of toxicity to human cells, incorporation by HIV reverse transcriptase, resistance to repair when incorporated into the DNA strand of an RNA\\cdot DNA hybrid, and mispairing at high frequency. Among the candidates tested, 5-hydroxydeoxycytidine (5-OH-dC) fulfilled these criteria. In seven of nine experiments, the presence of this analog resulted in the loss of viral replicative potential after 9-24 sequential passages of HIV in human CEM cells. In contrast, loss of viral replication was not observed in 28 control cultures passaged in the absence of the nucleoside analog, nor with other analogs tested. Sequence analysis of a portion of the HIV reverse transcriptase gene demonstrated a disproportionate increase in G -> A substitutions, mutations predicted to result from misincorporation of 5-OH-dC into the cDNA during reverse transcription. Thus, "lethal mutagenesis" driven by the class of deoxynucleoside analogs represented by 5-OH-dC could provide a new approach to treating HIV infections and, potentially, other viral infections.

  14. Dimerization and DNA recognition rules of mithramycin and its analogues.

    PubMed

    Weidenbach, Stevi; Hou, Caixia; Chen, Jhong-Min; Tsodikov, Oleg V; Rohr, Jürgen

    2016-03-01

    The antineoplastic and antibiotic natural product mithramycin (MTM) is used against cancer-related hypercalcemia and, experimentally, against Ewing sarcoma and lung cancers. MTM exerts its cytotoxic effect by binding DNA as a divalent metal ion (Me(2+))-coordinated dimer and disrupting the function of transcription factors. A precise molecular mechanism of action of MTM, needed to develop MTM analogues selective against desired transcription factors, is lacking. Although it is known that MTM binds G/C-rich DNA, the exact DNA recognition rules that would allow one to map MTM binding sites remain incompletely understood. Towards this goal, we quantitatively investigated dimerization of MTM and several of its analogues, MTM SDK (for Short side chain, DiKeto), MTM SA-Trp (for Short side chain and Acid), MTM SA-Ala, and a biosynthetic precursor premithramycin B (PreMTM B), and measured the binding affinities of these molecules to DNA oligomers of different sequences and structural forms at physiological salt concentrations. We show that MTM and its analogues form stable dimers even in the absence of DNA. All molecules, except for PreMTM B, can bind DNA with the following rank order of affinities (strong to weak): MTM=MTM SDK>MTM SA-Trp>MTM SA-Ala. An X(G/C)(G/C)X motif, where X is any base, is necessary and sufficient for MTM binding to DNA, without a strong dependence on DNA conformation. These recognition rules will aid in mapping MTM sites across different promoters towards development of MTM analogues as useful anticancer agents. PMID:26760230

  15. Cytotoxicity of methoctramine and methoctramine-related polyamines.

    PubMed

    Zini, Maddalena; Passariello, Catherine L; Gottardi, Davide; Cetrullo, Silvia; Flamigni, Flavio; Pignatti, Carla; Minarini, Anna; Tumiatti, Vincenzo; Milelli, Andrea; Melchiorre, Carlo; Stefanelli, Claudio

    2009-10-30

    Methoctramine and its analogues are polymethylene tetramines that selectively bind to a variety of receptor sites. Although these compounds are widely used as pharmacological tools for receptor characterization, the toxicological properties of these polyamine-based structures are largely unknown. We have evaluated the cytotoxic effects of methoctramine and related symmetrical analogues differing in polymethylene chain length between the inner nitrogens against a panel of cell lines. Methoctramine caused cell death only at high micromolar concentrations, whereas its pharmacological action is exerted at nanomolar level. Increasing the spacing between the inner nitrogen atoms resulted in a significative increase in cytotoxicity. In particular, an elevated cytotoxicity is associated to a methylene chain length of 12 units dividing the inner amine functions (compound 5). H9c2 cardiomyoblasts were the most sensitive cells, followed by SH-SY5Y neuroblastoma, whereas HL60 leukaemia cells were much more resistant. Methoctramine and related compounds down-regulated ornithine decarboxylase, the first enzyme of polyamine biosynthesis even at non-toxic concentration. Further, methoctramine and compound 5 caused a limited up-regulation of spermine/spermidine N-acetyltransferase, suggesting that interference in polyamine metabolism is not a primary mechanism of toxicity. Methoctramine and its analogues bound to DNA with a higher affinity than spermine, but the correlation with their toxic effect was poor. The highly toxic compound 5 killed the cells in the absence of caspase activation and caused an increase in p53 expression and ERK1/2 phosphorylation. Compound 5 was directly oxidized by cell homogenates producing hydrogen peroxide and its toxic effect was partially subdued by the inhibition of its uptake, by the NMDA ligand MK-801, and by the antioxidant N-acetylcysteine, suggesting that compound 5 can act at different cellular levels and lead to oxidative stress. PMID:19576191

  16. Demonstration in vitro of inhibition in normal rat tissues yet stimulation in Jensen sarcoma cells of 5-fluorouracil anabolism by purine nucleosides

    SciTech Connect

    Beltz, R.E.; Haddad-Zackrison, L.

    1986-05-01

    It has been shown previously that the ability of tumor cells to anabolize 5-fluorouracil (FUra) to nucleotides can often be enhanced by exposing the cells to various purine nucleosides. Increases in FUra cytotoxicity have been observed to accompany this enhancement. In the present study the effects of purine nucleosides on FUra anabolism in rat tumor cells and in normal rat tissues sensitive to FUra were compared. Pieces of small intestine (SI), bone marrow suspensions (BM) and Jensen tumor cells were incubated in culture medium at 37/sup 0/ for 1 hr in the presence (or absence) of a selected purine nucleoside, then (2-/sup 14/C)FUra was added and the incubation was continued for another hr. Incorporation of radioactivity into the trichloroacetic acid-insoluble fraction in each case was determined as a measure of FUra anabolism. Inosine, adenosine and N/sup 6/-methyl-adenosine, 1 mM, stimulated FUra incorporation into the acid-insoluble fraction 2-3 fold in the tumor cells but inhibited this incorporation 59-70% in SI and 31-70% in BM. Attempts to further suppress FUra anabolism in the normal tissues resulted in a maximal inhibition of 92% in SI, using 1 mM alloxanthine, and a maximal inhibition of 84% in BM, employing combined 1 mM alloxanthine and 1 mM 5-aminoimidazole-4-carbox-amide ribonucleoside. These data suggest ways of selectively altering FUra anabolism in normal tissue and in tumor tissue of the tumor-bearing rat to improve the therapeutic index of FUra.

  17. Radiolabeled nucleoside analogs in cancer diagnosis and therapy.

    PubMed

    Kassis, A I; Adelstein, S J; Mariani, G

    1996-09-01

    Radiolabeled nucleosides, specifically 5-iodo-2'-deoxyuridine (IUdR) radioiodinated with the Auger-electronemitting 123I or 125I, have been shown to produce extensive DNA damage in mammalian cell systems in vitro. Such nucleosides are cycle-dependent agents that are taken up by mitotically dividing cells in the S phase of the cell cycle. The degree of damage that occurs is related to the fact that these nucleosides bind covalently to DNA bringing the decaying Augerelectron-emitting radionuclide in close proximity to the genome. The use of these radiohalogenated nucleosides in vivo is associated with several problems. The first relates to their extremely short biologic half-life in blood (T1/2 of minutes in humans). The second involves achieving therapeutic ratios in tumor cells in the face of efficient hepatic dehalogenation. The third concerns the uptake of these radiopharmaceuticals by actively proliferating normal cell renewal systems, thus potentially causing toxic side effects. The fourth, one shared with other cycle-dependent drugs, relates to the matter of labeling the whole tumor cell population. To facilitate targeting to tumors, investigators have been examining the direct introduction of these agents into the targeted area or into an arterial blood supply that immediately precedes the target. For example, radiopharmaceutical administration could be intracavitary (bladder, spinal fluid, peritoneum), intralesional (brain tumor, breast mass) or intra-arterial (liver, pancreas). In all these situations, the following conditions must be met: (a) once within the vicinity of the tumor the agent can freely diffuse through the tissues and is selectively taken up by cancerous cells; (b) once the agent has left the target area it is converted quickly into a nontoxic form and/or excreted from the body; and finally, (c) the biologic behavior of the agent is not altered by repeated injections. We report herein our experience and that of others with [123I/125I/131I

  18. Structure activity-relationship and in vitro and in vivo evaluation of the potent cytotoxic anti-microtubule agent N-(4-methoxyphenyl)-N,2,6-trimethyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-aminium chloride and its analogues as antitumor agents

    PubMed Central

    Gangjee, Aleem; Zhao, Ying; Raghavan, Sudhir; Rohena, Cristina; Mooberry, Susan L.; Hamel, Ernest

    2013-01-01

    A series of 21 substituted cyclopenta[d]pyrimidines were synthesized as an extension of our discovery of the parent compound 1·HCl as an antimicrotubule agent. The structure-activity relationship indicates that the N-methyl and a 4′-methoxy groups appear important for potent activity. In addition, the 6-substituent in the parent analogue is not necessary for activity. The most potent compound 30·HCl was a 1–2 digit nanomolar inhibitor of most tumor cell proliferations and was up to 7-fold more potent than the parent compound 1·HCl. In addition, 30·HCl inhibited cancer cell proliferation regardless of Pgp or βIII-tubulin status, both of which are known to cause clinical resistance to several antitubulin agents. In vivo efficacy of 30·HCl was demonstrated against a triple negative breast cancer xenograft mouse model. Compound 30·HCl is water soluble, easily synthesized and serves as a lead compound for further preclinical evaluation as an antitumor agent. PMID:23895532

  19. Synthesis and Cytostatic Evaluation of 4-N-Alkanoyl and 4-N-Alkyl Gemcitabine Analogues

    PubMed Central

    Pulido, Jesse; Sobczak, Adam J.; Balzarini, Jan; Wnuk, Stanislaw F.

    2014-01-01

    Couplings of gemcitabine with the functionalized carboxylic acids (C9-C13) or reactions of 4-N-tosylgemcitabine with the corresponding alkyl amines afforded 4-N-alkanoyl and 4-N-alkyl gemcitabine derivatives. The analogues with a terminal hydroxyl group on the alkyl chain were efficiently fluorinated under conditions that are compatible with protocols for 18F labeling. The 4-N-alkanoylgemcitabines showed potent cytostatic activities in the low nM range against a panel of tumor cell lines while cytotoxicity of the 4-N-alkylgemcitabines were in the low μM range. The cytotoxicity for the 4-N-alkanoylgemcitabine analogues were reduced approximately by two orders of magnitude in the 2′-deoxycytidine kinase (dCK)-deficient CEM/dCK- cell line whereas cytotoxicity of the 4-N-alkylgemcitabines were only 2-5 times lower. None of the compounds acted as efficient substrates for cytosolic dCK, and therefore, the 4-N-alkanoyl analogues need to be converted first to gemcitabine to display a significant cytostatic potential, while 4-N-alkyl derivatives attain the modest activity without “measurable” conversion to gemcitabine. PMID:24341356

  20. Analysis of neurocognitive function and CNS endpoints in the PROTEA trial: darunavir/ritonavir with or without nucleoside analogues

    PubMed Central

    Clarke, Amanda; Johanssen, Veronika; Gerstoft, Jan; Clotet, Bonaventura; Ripamonti, Diego; Murungi, Andrew; Bicer, Ceyhun; Blanca Hadacek, Maria; Moecklinghoff, Christiane

    2014-01-01

    Introduction During treatment with protease inhibitor monotherapy, the number of antiretrovirals with therapeutic concentrations in the cerebrospinal fluid (CSF) is lower, compared to standard triple therapy. However, the clinical consequences are unclear. Methods A total of 273 patients with HIV RNA <50 copies/mL for over 24 weeks on current antiretrovirals randomized to darunavir/ritonavir (DRV/r) 800/100 mg once-daily, either as monotherapy (n=137) or with 2NRTIs (n=136). Neurocognitive function was evaluated in all patients by the Hopkins Verbal Learning Tests, the Colour Trail Tests and the Grooved Pegboard Test at screening, baseline and at Week 48. A global neurocognitive score (NPZ-5) was derived by averaging the standardized results of the five domains. In a central nervous system (CNS) sub-study (n=70), HIV RNA levels in the CNS were evaluated at baseline and Week 48. Clinical adverse events related to the CNS were collected at each visit. Results Patients were 83% male and 88% White, with median age 43 years. There were more patients with nadir CD4 count below 200 cells/µL in the DRV/r monotherapy arm (41/137, 30%) than the triple therapy arm (30/136, 22%). At Week 48, there was no difference between the treatment arms for the five combined domains of the neurocognitive score. At Week 48, the percentage of patients with an abnormal neurocognitive score among the five domains was 12.2% for DRV/r monotherapy and 14.9% for triple therapy. However, one patient on DRV/r monotherapy with a CD4 nadir of 17 cells/µL was hospitalized with HIV encephalomyelitis at Week 24, with HIV RNA 2500 copies/mL in the CSF and 125 copies/mL in the plasma. Symptoms resolved after intensification with high dose zidovudine. A second patient on DRV/r monotherapy with CD4 nadir of 166 cells/µL had a rise in HIV RNA in CSF from <40 copies/mL at baseline to 654 copies/mL at Week 48, with concurrent plasma HIV RNA of 77 copies/mL. Conclusions In this study for patients with HIV RNA <50 copies/mL at baseline, there was no difference in neurocognitive function between the treatment arms. However two patients on PI monotherapy with CD4 nadir <200 cells/µL developed viraemia in both CSF and plasma, with one symptomatic case. DRV/r monotherapy should be used with caution in patients with nadir CD4 counts below 200 cells/µL. PMID:25394035

  1. Transport of physiological nucleosides and anti-viral and anti-neoplastic nucleoside drugs by recombinant Escherichia coli nucleoside-H(+) cotransporter (NupC) produced in Xenopus laevis oocytes.

    PubMed

    Loewen, Shaun K; Yao, Sylvia Y M; Slugoski, Melissa D; Mohabir, Nadira N; Turner, Raymond J; Mackey, John R; Weiner, Joel H; Gallagher, Maurice P; Henderson, Peter J F; Baldwin, Stephen A; Cass, Carol E; Young, James D

    2004-01-01

    The recently identified human and rodent plasma membrane proteins CNT1, CNT2 and CNT3 belong to a gene family (CNT) that also includes the bacterial nucleoside transport protein NupC. Heterologous expression in Xenopus oocytes has established that CNT1-3 correspond functionally to the three major concentrative nucleoside transport processes found in human and other mammalian cells (systems cit, cif and cib, respectively) and mediate Na(+) - linked uptake of both physiological nucleosides and anti-viral and anti-neoplastic nucleoside drugs. Here, one describes a complementary Xenopus oocyte transport study of Escherichia coli NupC using the plasmid vector pGEM-HE in which the coding region of NupC was flanked by 5'- and 3'-untranslated sequences from a Xenopus beta-globin gene. Recombinant NupC resembled human (h) and rat (r) CNT1 in nucleoside selectivity, including an ability to transport adenosine and the chemotherapeutic drugs 3'-azido-3'-deoxythymidine (AZT), 2',3'- dideoxycytidine (ddC) and 2'-deoxy-2',2'-difluorocytidine (gemcitabine), but also interacted with inosine and 2',3'- dideoxyinosine (ddl). Apparent affinities were higher than for hCNT1, with apparent K(m) values of 1.5-6.3 microM for adenosine, uridine and gemcitabine, and 112 and 130 microM, respectively, for AZT and ddC. Unlike the relatively low translocation capacity of hCNT1 and rCNT1 for adenosine, NupC exhibited broadly similar apparent V(max) values for adenosine, uridine and nucleoside drugs. NupC did not require Na(+) for activity and was H(+) - dependent. The kinetics of uridine transport measured as a function of external pH were consistent with an ordered transport model in which H(+) binds to the transporter first followed by the nucleoside. These experiments establish the NupC-pGEM-HE/oocyte system as a useful tool for characterization of NupC-mediated transport of physiological nucleosides and clinically relevant nucleoside therapeutic drugs. PMID:14668133

  2. Cytotoxic cytochalasins from marine-derived fungus Arthrinium arundinis.

    PubMed

    Wang, Junfeng; Wang, Zhen; Ju, Zhiran; Wan, Junting; Liao, Shengrong; Lin, Xiuping; Zhang, Tianyu; Zhou, Xuefeng; Chen, Hao; Tu, Zhengchao; Liu, Yonghong

    2015-01-01

    Four new cytochalasins, arthriniumnins A-D (1-4), a new natural product, ketocytochalasin (5), as well as five known cytochalasin analogues (6-10) were isolated and identified from the fungus Arthrinium arundinis ZSDS1-F3 from the sponge Phakellia fusca. Their structures were elucidated by NMR spectroscopic and mass spectrometric analyses, as well as single crystal X-ray diffraction. Compounds 6 and 9 showed cytotoxicity against K562, A549, Huh-7, H1975, MCF-7, U937, BGC823, HL60, Hela, and MOLT-4 cell lines, with IC50 values ranging from 1.13 to 47.4 µM. PMID:25626143

  3. Cytotoxic acylphloroglucinol derivatives from the twigs of Garcinia cowa.

    PubMed

    Xu, Gang; Kan, Winnie L T; Zhou, Yan; Song, Jing-Zheng; Han, Quan-Bin; Qiao, Chun-Feng; Cho, Chi-Hin; Rudd, John A; Lin, Ge; Xu, Hong-Xi

    2010-02-26

    An unusual polyprenylated acylphloroglucinol derivative unsubstituted at C-2 and C-6, garcicowin A (1), together with three other new (garcicowins B-D, 2-4) and nine known analogues, was isolated and characterized from the twigs of Garcinia cowa. The structures of 1-4 were elucidated by interpretation of their spectroscopic data. The compounds isolated were evaluated for their cytotoxicity against two cancer cell lines (HT-29 and HCT116) and against normal colon cells (CCD-18Co), and the results demonstrated their selective toxicity toward the cancer cells. PMID:20058933

  4. Modulation of nicotinamide adenine dinucleotide and poly(adenosine diphosphoribose) metabolism by the synthetic "C" nucleoside analogs, tiazofurin and selenazofurin. A new strategy for cancer chemotherapy.

    PubMed Central

    Berger, N A; Berger, S J; Catino, D M; Petzold, S J; Robins, R K

    1985-01-01

    Tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide) and selenazofurin (2-beta-D-ribofuranosylselenazole-4-carboxamide) are synthetic "C" nucleosides whose antineoplastic activity depends on their conversion to tiazofurin-adenine dinucleotide and selenazofurin-adenine dinucleotide which are analogs of NAD. The present study was conducted to determine whether these nucleoside analogs and their dinucleotide derivatives interfere with NAD metabolism and in particular with the NAD-dependent enzyme, poly(ADP-ribose) polymerase. Incubation of L1210 cells with 10 microM tiazofurin or selenazofurin resulted in inhibition of cell growth, reduction of cellular NAD content, and interference with NAD synthesis. Using [14C]nicotinamide to study the uptake of nicotinamide and its conversion to NAD, we showed that the analogs interfere with NAD synthesis, apparently by blocking formation of nicotinamide mononucleotide. The analogs also serve as weak inhibitors of poly(ADP-ribose) polymerase, which is an NAD-utilizing, chromatin-bound enzyme, whose function is required for normal DNA repair processes. Continuous incubation of L1210 cells in tiazofurin or selenazofurin resulted in progressive and synergistic potentiation of the cytotoxic effects of DNA-damaging agents, such as 1,3-bis(2-chloroethyl)-1-nitrosourea or N-methyl-N'-nitro-N-nitrosoguanidine. These studies provide a basis for designing chemotherapy combinations in which tiazofurin or selenazofurin are used to modulate NAD and poly(ADP-ribose) metabolism to synergistically potentiate the effects of DNA strand-disrupting agents. PMID:3919063

  5. The chemical synthesis and preliminary biological studies of phosphodiester and phosphorothioate analogues of 2-methoxy-lysophosphatidylethanolamine.

    PubMed

    Sowińska, Agata; Rytczak, Przemysław; Gendaszewska-Darmach, Edyta; Drzazga, Anna; Koziołkiewicz, Maria; Okruszek, Andrzej

    2016-08-01

    The chemical synthesis of phosphorothioate/phosphodiester analogues of 2-methoxy-lysophosphatidylethanolamine has been described. For the preparation of phosphorothioate derivatives oxathiaphospholane approach has been employed. The phosphodiester compounds were prepared by OXONE® oxidation of corresponding phosphorothioates. Each lysophospholipid analogue was synthesized as a series of four compounds, bearing different fatty acid residues both saturated (14:0, 16:0, 18:0) and unsaturated (18:1). The methylation of glycerol 2-hydroxyl function was applied in order to increase the stability of prepared analogues by preventing 1→2 acyl migration. The cytotoxicity of newly synthesized 2-methoxy-lysophosphatidylethanolamine derivatives was evaluated with resazurin-based method in prostate cancer PC3 cell line. The highest reduction of cell viability was noted for LPE analogues containing myristoyl acyl chain. PMID:27268697

  6. The histone deacetylase inhibitor SAHA sensitizes acute myeloid leukemia cells to a combination of nucleoside analogs and the DNA-alkylating agent busulfan.

    PubMed

    Song, Guiyun; Valdez, Benigno C; Li, Yang; Dominguez, Jose R; Corn, Paul; Champlin, Richard E; Andersson, Borje S

    2014-07-01

    Fludarabine (Flu), clofarabine (Clo) and busulfan (Bu) are used in allogeneic hematopoietic stem cell transplant (allo-HSCT). We reported that combining [Flu + Clo + Bu] had a synergistic cytotoxicity in AML cells. We hypothesized that combining [Flu + Clo + Bu] with the histone deacetylase inhibitor SAHA will further enhance cytotoxicity. We exposed the acute myeloid leukemia (AML) cell lines KBM3/Bu250(6) and OCI-AML3 to Flu, Clo, Bu and SAHA alone and in various combinations. [Flu + Clo + Bu + SAHA] resulted in synergistic cytotoxicity, which can be attributed to (1) activated DNA-damage response and cell cycle checkpoint activation through the ATM-CHK2-P53 (or P73) pathway or ATM-CHK2-cdc25-cdc2 pathway, (2) histone modifications and (3) activated apoptosis pathway. The [Flu + Clo + Bu + SAHA] combination causes mitochondrial outer membrane permeabilization, leakage of cytochrome c and Smac/Diablo into the cytosol with caspase activation, and release of apoptosis-inducing factor (AIF) into the nucleus resulting in nuclear fragmentation and cell death. These results provide a mechanistic basis for using SAHA in future clinical trials with double nucleoside analog-busulfan combinations in pretransplant conditioning therapy. PMID:24144307

  7. Modified nucleosides as biomarkers for early cancer diagnose in exposed populations.

    PubMed

    Seidel, Annerose; Seidel, Peter; Manuwald, Olaf; Herbarth, Olf

    2015-07-01

    There is increasing worldwide interest in developing of markers for tumor diagnosis and identification of individuals who are at high cancer risk. Cancer, like other diseases accompanied by metabolic disorders, causes characteristic effects on cell turnover rate, activity of modifying enzymes, and RNA/DNA modifications. This results in an increased excretion of modified nucleosides in cancer patients. Therefore, for many years modified nucleosides have been suggested as tumor markers. The aim of the study was to elucidate further the usefulness of urinary nucleosides as possible markers at early detection of cancer in persons which are exposed against tumor promoting influences during their working life. Uranium miners are exposed to many kinds of pollutants that can cause health damage even lead to carcinogenesis. We analyzed modified nucleosides in urine samples from 92 miners who are at high risk for lung cancer to assess the levels of nucleosides by a multilayer perceptron (MLP) classifier - a neural network model. Eighteen nucleosides/metabolites were detected with reversed-phase high-pressure liquid chromatography (RP-HPLC). A valid set of urinary metabolites were selected and multivariate statistical technique of multilayer perceptron neural network were applied. In a previous study, MLP shows a sensitivity and specificity of 97 and 85%, respectively. MLP classification including the most relevant markers/nucleosides clearly demonstrates the elevation of RNA metabolism in miners, which is associated with possible malignant disease. We found that there were 30 subjects with early health disorders among 92 uranium workers based on MLP technique using modified nucleosides. The combination of RP-HPLC analysis of modified nucleosides and subsequent MLP analyses represents a promising tool for the development of a non-invasive prediction system and may assist in developing management and surveillance procedures. PMID:24615900

  8. Synthesis of cycloalkyl substituted purine nucleosides via a metal-free radical route.

    PubMed

    Wang, Dong-Chao; Xia, Ran; Xie, Ming-Sheng; Qu, Gui-Rong; Guo, Hai-Ming

    2016-05-01

    An efficient route to synthesize cycloalkyl substituted purine nucleosides was developed. This metal-free C-H activation was accomplished by a tBuOOtBu initiated radical reaction. By adjusting the amount of tBuOOtBu and reaction time, the selective synthesis of C6-monocycloalkyl or C6,C8-dicycloalkyl substituted purine nucleosides could be realized. Furthermore, uracil and related nucleosides were also suitable substrates, giving the C5-cyclohexyl substituted uracil derivatives in good yields with excellent regioselectivities. PMID:27101306

  9. Synthesis of α-l-Threofuranosyl Nucleoside Triphosphates (tNTPs)

    PubMed Central

    Zou, Keyong; Horhota, Allen; Yu, Biao; Szostak, Jack W.

    2005-01-01

    The α-l-threofuranosyl nucleoside triphosphates of T, G, and D (tTTP, tGTP, and tDTP) were synthesized from the described 2‘-O-DMT-protected derivatives using the Eckstein method, while the corresponding C derivative (tCTP) was prepared from the 2‘-O-acetyl derivative. The prepared α-l-threofuranosyl nucleoside triphosphates, despite being one carbon shorter than the native 2‘-deoxyfuranosyl nucleoside triphosphates, are effective substrates for selected DNA polymerases. PMID:15816733

  10. The search for nucleoside/nucleotide analog inhibitors of dengue virus.

    PubMed

    Chen, Yen-Liang; Yokokawa, Fumiaki; Shi, Pei-Yong

    2015-10-01

    Nucleoside analogs represent the largest class of antiviral agents and have been actively pursued for potential therapy of dengue virus (DENV) infection. Early success in the treatment of human immunodeficiency virus (HIV) infection and the recent approval of sofosbuvir for chronic hepatitis C have provided proof of concept for this class of compounds in clinics. Here we review (i) nucleoside analogs with known anti-DENV activity; (ii) challenges of the nucleoside antiviral approach for dengue; and (iii) potential strategies to overcome these challenges. This article forms part of a symposium in Antiviral Research on flavivirus drug discovery. PMID:26241002

  11. Identification of a novel compound that inhibits osteoclastogenesis by suppressing nucleoside transporters.

    PubMed

    Katsuyama, Shun; Sugino, Kumi; Sasazawa, Yukiko; Nakano, Yoshihiko; Aono, Harumi; Morishita, Keisuke; Kawatani, Makoto; Umezawa, Kazuo; Osada, Hiroyuki; Simizu, Siro

    2016-04-01

    We screened small-molecule compounds that inhibit osteoclast differentiation to find new anti-osteoporosis agents and found that a novel compound, SUKU-1, suppressed osteoclastogenesis. We also synthesized 38 derivatives of SUKU-1 and discovered that nine of them had inhibitory effects on osteoclastogenesis and that SUKU-33 was the most potent inhibitor. Next, we investigated the mechanisms by which SUKU-33 suppressed osteoclast differentiation. By measuring the uptake of [(3) H]-uridine in cells, we found that SUKU-33 suppressed both equilibrative nucleoside transporters and concentrative nucleoside transporters. These results suggest that SUKU-33 inhibits osteoclast differentiation by suppressing nucleoside transporters. PMID:27001232

  12. Application of crystallographic and modeling methods in the design of purine nucleoside phosphorylase inhibitors.

    PubMed Central

    Ealick, S E; Babu, Y S; Bugg, C E; Erion, M D; Guida, W C; Montgomery, J A; Secrist, J A

    1991-01-01

    Competitive inhibitors of the salvage pathway enzyme purine-nucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1) have been designed by using the three-dimensional structure of the enzyme as determined by x-ray crystallography. The process was an iterative one that utilized interactive computer graphics, Monte Carlo-based conformational searching, energy minimization, and x-ray crystallography. The proposed compounds were synthesized and tested by an in vitro assay. Among the compounds designed and synthesized are the most potent competitive inhibitors of purine nucleoside phosphorylase thus far reported. Images PMID:1763067

  13. An Efficient Protection-Free One-Pot Chemical Synthesis of Modified Nucleoside-5'-Triphosphates.

    PubMed

    Shanmugasundaram, Muthian; Senthilvelan, Annamalai; Xiao, Zejun; Kore, Anilkumar R

    2016-07-01

    A simple, reliable, and an efficient "one-pot, three step" chemical method for the synthesis of modified nucleoside triphosphates such as 5-methylcytidine-5'-triphosphate (5-MeCTP), pseudouridine-5'-triphosphate (pseudoUTP) and N(1)-methylpseudouridine-5'-triphosphate (N(1)-methylpseudoUTP) starting from the corresponding nucleoside is described. The overall reaction involves the monophosphorylation of nucleoside, followed by the reaction with pyrophosphate and subsequent hydrolysis of the cyclic intermediate to furnish the corresponding NTP in moderate yields with high purity (>99.5%). PMID:27159048

  14. Identification of Highly Promising Antioxidants/Neuroprotectants Based on Nucleoside 5'-Phosphorothioate Scaffold. Synthesis, Activity, and Mechanisms of Action.

    PubMed

    Azran, Sagit; Danino, Ortal; Förster, Daniel; Kenigsberg, Sarah; Reiser, Georg; Dixit, Mudit; Singh, Vijay; Major, Dan T; Fischer, Bilha

    2015-11-12

    With a view to identify novel and biocompatible neuroprotectants, we designed nucleoside 5'-thiophosphate analogues, 6-11. We identified 2-SMe-ADP(α-S), 7A, as a most promising neuroprotectant. 7A reduced ROS production in PC12 cells under oxidizing conditions, IC50 of 0.08 vs 21 μM for ADP. Furthermore, 7A rescued primary neurons subjected to oxidation, EC50 of 0.04 vs 19 μM for ADP. 7A is a most potent P2Y1-R agonist, EC50 of 0.0026 μM. Activity of 7A in cells involved P2Y1/12-R as indicated by blocking P2Y12-R or P2Y1-R. Compound 7A inhibited Fenton reaction better than EDTA, IC50 of 37 vs 54 μM, due to radical scavenging, IC50 of 12.5 vs 30 μM for ADP, and Fe(II)-chelation, IC50 of 80 vs >200 μM for ADP (ferrozine assay). In addition, 7A was stable in human blood serum, t1/2 of 15 vs 1.5 h for ADP, and resisted hydrolysis by NPP1/3, 2-fold vs ADP. Hence, we propose 7A as a highly promising neuroprotectant. PMID:26447940

  15. Synthesis of Chromone, Quinolone, and Benzoxazinone Sulfonamide Nucleosides as Conformationally Constrained Inhibitors of Adenylating Enzymes Required for Siderophore Biosynthesis

    PubMed Central

    Engelhart, Curtis A.; Aldrich, Courtney C.

    2013-01-01

    MbtA catalyzes the first committed step of mycobactin biosynthesis in Mycobacterium tuberculosis (Mtb) and is responsible for the incorporation of salicylic acid into the mycobactin siderophores. 5′-O-[N-(Salicyl)sulfamoyl]adenosine (Sal-AMS) is an extremely potent nucleoside inhibitor of MbtA that possesses excellent activity against whole-cell Mtb, but suffers from poor bioavailability. In an effort to improve the bioavailability, we have designed four conformationally constrained analogues of Sal-AMS that remove two rotatable bonds and the ionized sulfamate group based on computational and structural studies. Herein we describe the synthesis, biochemical, and microbiological evaluation of chromone-, quinolone-, and benzoxazinone-3-sulfonamide derivatives of Sal-AMS. We developed new chemistry to assemble these three heterocycles from common β-ketosulfonamide intermediates. The synthesis of the chromone- and quinolone-3-sulfonamide intermediates features formylation of a β-ketosulfonamide employing dimethylformamide dimethyl acetal to afford an enaminone that can react intramolecularly with a phenol or intermolecularly with a primary amine via addition-elimination reaction(s). The benzoxazinone-3-sulfonamide was prepared by nitrosation of a β-ketosulfonamide followed by intramolecular nucleophilic aromatic substitution. Mitsunobu coupling of these bicyclic sulfonamides with a protected adenosine derivative followed by global deprotection provides a concise synthesis of the respective inhibitors. PMID:23805993

  16. Telomerase inhibition by non-nucleosidic compound BIBR1532 causes rapid cell death in pre-B acute lymphoblastic leukemia cells.

    PubMed

    Bashash, Davood; Ghaffari, Seyed H; Mirzaee, Rooholah; Alimoghaddam, Kamran; Ghavamzadeh, Ardeshir

    2013-03-01

    Since unlimited proliferative potential has been identified as a major and, to date, therapeutically unexploited phenotypic hallmark of cancer, telomere maintenance mechanisms have been proposed as potential targets for new anticancer interventions. This study was aimed to investigate the effects of BIBR1532, the lead compound of non-nucleosidic inhibition of telomerase, on pre-B acute lymphoblastic leukemia (ALL) cells. BIBR1532 caused rapid cell death in Nalm-6 cells probably through transcriptional suppression of survivin-mediated c-Myc and human telomerase reverse transcriptase (hTERT) expression in a concentration-dependent manner. Moreover, our results also suggest that induced p73, up-regulated Bax/Bcl-2 molecular ratio and subsequent activation of caspase-3 may contribute to a direct short-term cytotoxic effect of high doses of BIBR1532, independent of long-term substantial telomere erosion-mediated cell cycle arrest. PMID:22957790

  17. Autoxidation and cytotoxicity

    SciTech Connect

    Borg, D C; Schaich, K M; Elmore, Jr, J J

    1980-01-01

    A comprehensive synthesis, or reaction schema, to relate autoxidations of non-lipid compounds to lipid chain peroxidation in vivo is presented. This is done in the context of cytotoxic autoxidation reactions, and it is concluded that hydroxyl radicals produced by iron-dependent Fenton reactions serve as both primary toxicants and as sources of secondary toxicants. The latter stem from lipid chain peroxidation initiated by the Fenton-derived hydroxyl radicals, which are visualized as the obligate coupling step linking enzyme-dependent and non-enzymic autoxidations to potentially toxic outcomes.

  18. Muscarinic interactions of bisindolylmaleimide analogues.

    PubMed

    Lazareno, S; Popham, A; Birdsall, N J

    1998-11-01

    We have used radioligand binding studies to determine the affinities of seven bisindolylmaleimide analogues, six of which are selective inhibitors of protein kinase C, at human muscarinic M1-M4 receptors. The compounds were most potent at M1 receptors, and Ro-31-8220 was the most potent analogue, with a Kd of 0.6 microM at M1 receptors. The weakest compounds, bisindolylmaleimide IV and bisindolylmaleimide V, had Kd values of 100 microM. If it is necessary to use protein kinase C inhibitors at concentrations of 10 microM or more in studies involving muscarinic receptors then bisindolylmaleimide IV may be the most appropriate inhibitor to use. PMID:9851596

  19. RIBOSE MODIFIED NUCLEOSIDES AND NUCLEOTIDES AS LIGANDS FOR PURINE RECEPTORS

    PubMed Central

    Ravi, R. G.; Nandanan, E.; Kim, H. S.; Moro, S.; Kim, Y. C.; Lee, K.; Barak, D.; Marquez, V. E.; Ji, X. D.

    2016-01-01

    Molecular modeling of receptors for adenosine and nucleotide (P2) receptors with docked ligand, based on mutagenesis, was carried out. Adenosine 3′,5′-bisphosphate derivatives act as selective P2Y1 antagonists/partial agonists. The ribose moiety was replaced with carbocyclics, smaller and larger rings, conformationally constrained rings, and acyclics, producing compounds that retained receptor affinity. Conformational constraints were built into the ribose rings of nucleoside and nucleotide ligands using the methanocarba approach, i.e. fused cyclopropane and cyclopentane rings in place of ribose, suggesting a preference for the Northern (N) conformation among ligands for P2Y1 and A1 and A3ARs. PMID:11563046

  20. Substrate analogues for isoprenoid enzymes

    SciTech Connect

    Stremler, K.E.

    1987-01-01

    Diphosphonate analogues of geranyl diphosphate, resistant to degradation by phosphatases, were found to be alternate substrates for the reaction with farnesyl diphosphate synthetase isolated from avian liver. The difluoromethane analogue was shown to be the better alternate substrate, in agreement with solvolysis results which indicate that the electronegativity of the difluoromethylene unit more closely approximates that of the normal bridging oxygen. The usefulness of the C/sub 10/ difluoro analogue, for detecting low levels of isoprenoid enzymes in the presence of high levels of phosphatase activity, was demonstrated with a cell-free preparation from lemon peel. A series of C/sub 5/ through C/sub 15/ homoallylic and allylic diphosphonates, as well as two 5'-nucleotide diphosphonates, was prepared in high overall yield using the activation-displacement sequence. Radiolabeled samples of several of the allylic diphosphonates were prepared with tritium located at C1. A series of geraniols, stereospecifically deuterated at C1, was prepared. The enantiomeric purities and absolute configurations were determined by derivatization as the mandelate esters for analysis by /sup 1/H NMR. The stereochemistry of the activation-displacement sequence was examined using C1-deuterated substrates.

  1. Policy issues in space analogues

    NASA Astrophysics Data System (ADS)

    Auger, Robin N.; Facktor, Debra D.

    Space mission planning is increasingly focusing on destinations beyond Earth orbit. Advancements in technology will inevitably be required to enable long-duration human spaceflight missions, and breakthroughs in the policy arena will also be needed to achieve success in such missions. By exploring how policy issues have been addressed in analogous extreme environments, policymakers can develop a framework for addressing these issues as they apply to long-term human spaceflight. Policy issues that need to be addressed include: crew selection, training, organization, and activities, medical testing, illness, injury, and death; communication; legal accountability and liability; mission safety and risk management; and environmental contamination. This paper outlines the approach of a study underway by The George Washington University and ANSER to examine how these policy issues have been addressed in several analogues and how the experiences of these analogues can help formulate policies for long-duration human spaceflight missions. Analogues being studied include Antarctic bases, submarine voyages, undersea stations, Biosphere 2, and the U.S. Skylab and Russian Mir space stations.

  2. Phosphonate analogue substrates for enolase.

    PubMed

    Anderson, V E; Cleland, W W

    1990-11-20

    Phosphonate analogues in which the bridge between C-2 and phosphorus is a CH2 group are slow substrates for yeast enolase. The pH variation of the kinetic parameters for the methylene analogue of 2-phosphoglycerate suggests that the substrate binds as a dianion and that Mg2+ can bind subsequently only if a metal ligand and the catalytic base are unprotonated. Primary deuterium isotope effects of 4-8 on V/KMg, but ones of only 1.15-1.32 on V for dehydration, show that proton removal to give the carbanion intermediate largely limits V/KMg and that a slow step follows which largely limits V (presumably carbanion breakdown). Since there is a D2O solvent isotope effect on V for the reverse reaction of 5, but not an appreciable one on the forward reaction, it appears that the slow rates with phosphonate analogues result from the fact that the carbanion intermediate is more stable than that formed from the normal substrates, and its reaction in both directions limits V. Increased stability as a result of replacement of oxygen by carbon at C-2 of the carbanion is the expected chemical behavior. PMID:2271661

  3. Cytotoxicity of denture adhesives.

    PubMed

    de Gomes, Pedro Sousa; Figueiral, Maria Helena; Fernandes, Maria Helena R; Scully, Crispian

    2011-12-01

    Ten commercially available denture adhesives, nine soluble formulations (six creams, three powders) and one insoluble product (pad), were analyzed regarding the cytotoxicity profile in direct and indirect assays using L929 fibroblast cells. In the direct assay, fibroblasts were seeded over the surface of a thick adhesive gel (5%, creams; 2.5%, powders and pad). In the indirect assay, cells were cultured in the presence of adhesive extracts prepared in static and dynamic conditions (0.5-2%, creams; 0.25-1%, powders and pad). Cell toxicity was assessed for cell viability/proliferation (MTT assay) and cell morphology (observation of the F-actin cytoskeleton organization by confocal laser scanning microscopy). Direct contact of the L929 fibroblasts with the thick adhesive gels caused no, or only a slight, decrease in cell viability/proliferation. The adhesive extracts (especially those prepared in dynamic conditions) caused significantly higher growth inhibition of fibroblasts and, in addition, caused dose- and time-dependent effects, throughout the 6-72 h exposure time. Also, dose-dependent effects on cell morphology, with evident disruption of the F-actin cytoskeleton organization, were seen in the presence of most adhesives. In conclusion, the adhesives possessed different degrees of cytotoxicity, but similar dose- and time-dependent biological profiles. PMID:20844908

  4. A computational study of open-chain epothilone analogue

    NASA Astrophysics Data System (ADS)

    Kamel, Karol; Rusinska-Roszak, Danuta

    Molecular mechanics (MM/Ambers) calculations were applied to probe the conformational profile of open-chain epothilone analogue [Org Lett 2006, 8, 685], cytotoxic against some cell lines. Geometries of the most stable conformers were optimized at DFT level using the B3LYP functional and then compared to known both experimental and virtual conformers of epothilone. One of the most stable structures is III (1.47 kcal/mol above global minimum) which represents high similarity to the appropriate fragment of the Taylor's model of epothilone A, but two other conformers: XIV and XX, although they have almost the same conformation as the mother structure, are very unstable (6.7 and 12.4 kcal/mol above the global minimum).0

  5. Novel indole-3-sulfonamides as potent HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs)

    SciTech Connect

    Zhao, Zhijian; Wolkenberg, Scott E.; Lu, Meiqing; Munshi, Vandna; Moyer, Gregory; Feng, Meizhen; Carella, Anthony V.; Ecto, Linda T.; Gabryelski, Lori J.; Lai, Ming-Tain; Prasad, Sridar G.; Yan, Youwei; McGaughey, Georgia B.; Miller, Michael D.; Lindsley, Craig W.; Hartman, George D.; Vacca, Joseph P.; Williams, Theresa M.

    2008-09-29

    This Letter describes the design, synthesis, and biological evaluation of novel 3-indole sulfonamides as potent non-nucleoside reverse transcriptase inhibitors (NNRTIs) with balanced profiles against common HIV RT mutants K103N and Y181C.

  6. KP-1212/1461, a nucleoside designed for the treatment of HIV by viral mutagenesis.

    PubMed

    Harris, Kevin S; Brabant, William; Styrchak, Sheila; Gall, Alexander; Daifuku, Richard

    2005-07-01

    We report the activities of a novel nucleoside analog against HIV. This nucleoside (KP-1212) is not a chain terminator but exerts its antiviral effects via mutagenesis of the viral genome. Serial passaging of HIV in the presence of KP-1212 causes an increase in the mutation rate of the virus leading to viral ablation. HIV strains resistant to KP-1212 have not yet been isolated. Quite to the contrary, virus treated with KP-1212 exhibited an increased sensitivity not only to KP-1212 but also to another nucleoside reverse transcriptase inhibitor (NRTI), zidovudine. HIV strains resistant to other NRTIs (e.g. zidovudine, lamivudine, stavudine, abacavir, etc.) exhibited no cross-resistance towards KP-1212. Multiple assays confirmed that KP-1212 has a favorable (low) genotoxicity profile when compared to some approved antiviral nucleosides. In addition, KP-1212 is not toxic to mitochondria nor does it exhibit any inhibitory effects on mitochondrial DNA synthesis. PMID:15890415

  7. Comparison of nucleoside concentrations in blood of fish with and without tumors

    SciTech Connect

    Kuehl, D.W.; Johnson, R.D. ); Eisenschenk, L.; Naumann, S. ); Regal, R.; Barnidge, P. ); McKim, J. Jr. )

    1991-05-01

    The objective of this study was to develop and use HPLC based analytical methodology to characterize nucleosides in blood plasma and serum from fish with and without tumors, with a goal of determining if fish blood nucleoside concentrations could similarly be used as a bioindicator of tumor development in fish. The approach was to develop analytical methodology and quality assurance criteria for the analysis of nucleosides in fish blood, and to characterize nucleoside concentrations in blood of fish for which both healthy and tumor-bearing samples were available. Data would then be used to establish parameters with which tumor-bearing fish could be distinguished from healthy fish. Blood samples used to establish the diagnostic parameters were from control rainbow trout (Oncorhynchus mykiss) and those with tumors developed after exposure to aflatoxins. A second set of blood samples was from field collected black bullheads (Ictalurus melas).

  8. Synthesis and biological activities of the respiratory chain inhibitor aurachin D and new ring versus chain analogues

    PubMed Central

    Li, Xu-Wen; Herrmann, Jennifer; Zang, Yi; Grellier, Philippe; Prado, Soizic

    2013-01-01

    Summary Aurachins are myxobacterial 3-farnesyl-4(1H)-quinolone derived compounds initially described as respiratory chain inhibitors, more specifically as inhibitors of various cytochrome complexes. They are also known as potent antibiotic compounds. We describe herein the first synthesis of aurachin D through a key Conrad–Limpach reaction. The same strategy was used to reach some ring as opposed to chain analogues, allowing for the description of structure–activity relationships. Biological screening of the analogues showed antiparasitic, cytotoxic, antibacterial and antifungal activities, and depletion of the mitochondrial membrane potential. The strongest activity was found on Plasmodium falciparum with a selectivity index of 345, compared to Vero cells, for the natural product and its geranyl analogue. The loss of mitochondrial membrane potential induced by aurachins in human U-2 OS osteosarcoma cells was studied, showing the best activity for aurachin D and a naphthalene analogue, yet without totally explaining the observed cytotoxic activity of the compounds. Finally, a synthetic entry is given to the complete carboheterocyclic core of aurachin H through the N-oxidation/epoxidation of aurachin D and a shorter chain analogue, followed by subsequent biomimetic cyclization. PMID:23946854

  9. a Nucleoside Under Observation in the Gas Phase: a Rotational Study of Uridine

    NASA Astrophysics Data System (ADS)

    Peña, Isabel; Alonso, José L.

    2014-06-01

    The nucleoside of uridine has been placed in the gas phase by laser ablation and the most stable C2{'}-anti conformation characterized by broadband chirped pulse (CP-FTMW) and narrowband molecular beam Fourier transform microwave (LA-MB-FTMW) spectroscopies. The quadrupole hyperfine structure, originated by two 14N nuclei, has been completely resolved. Intramolecular hydrogen bonds involving uracil and ribose moieties have been found to play an important role in the stabilization of the nucleoside.

  10. Mild, efficient, selective and "green" benzoylation of nucleosides using benzoyl cyanide in ionic liquid.

    PubMed

    Prasad, Ashok K; Kumar, Vineet; Maity, Jyotirmoy; Sanghvi, Yogesh S; Ravikumar, Vasulinga T; Parmar, Virinder S

    2005-01-01

    Use of benzoyl cyanide (BzCN) for benzoylation of nucleosides has been studied, both in pyridine and in ionic liquid BzCN in 1-methoxyethyl-3-methylimidazolium methanesulfonate as ionic liquid has been found to be a "green "alternative compared to the pyridine-BzCN system. An efficient and selective benzoylation of nucleosides of both, the 2'-deoxy- and the ribo-series at ambient temperature was accomplished. PMID:16248029

  11. Telomerase inhibition and telomere targeting in hematopoietic cancer cell lines with small non-nucleosidic synthetic compounds (BIBR1532).

    PubMed

    El Daly, Hesham; Martens, Uwe M

    2007-01-01

    Telomere maintenance has been shown to be essential for unlimited growth potential of human cells and is regarded as one hallmark of cancer. Telomere repeats at the ends of eukaryotic chromosomes are synthesized by the enzyme telomerase, which is active in most cancers and to some extend also in normal somatic cells. Therefore, targeting the telomerase/telomere complex offers great potential for the development of novel anticancer therapeutics. An example of such a strategy is the small molecule BIBR1532 that is a selective, non-nucleosidic inhibitor of the catalytic component hTERT. Treatment of cancer cells with this compound leads to progressive telomere shortening, consecutive telomere dysfunction, and finally growth arrest after a lag period that is largely dependent on initial telomere length. We have additionally shown that using this class of telomerase inhibitor at higher concentrations exerts a direct cytotoxic effect on malignant cells of the hematopoietic system but not on normal stem cells, which appears to derive from direct damage to the structure of individual telomeres. PMID:18369817

  12. Leishmania (Viannia) braziliensis nucleoside triphosphate diphosphohydrolase (NTPDase 1): localization and in vitro inhibition of promastigotes growth by polyclonal antibodies.

    PubMed

    Porcino, Gabriane Nascimento; Carvalho-Campos, Cristiane; Maia, Ana Carolina Ribeiro Gomes; Detoni, Michelle Lima; Faria-Pinto, Priscila; Coimbra, Elaine Soares; Marques, Marcos José; Juliano, Maria Aparecida; Juliano, Luiz; Diniz, Vanessa Álvaro; Corte-Real, Suzana; Vasconcelos, Eveline Gomes

    2012-10-01

    Nucleoside triphosphate diphosphohydrolase (NTPDase) activity was recently characterized in Leishmania (Viannia) braziliensis promastigotes (Lb), and an antigenic conserved domain (r82-121) from the specific NTPDase 1 isoform was identified. In this work, mouse polyclonal antibodies produced against two synthetic peptides derived from this domain (LbB1LJ, r82-103; LbB2LJ, r102-121) were used. The anti-LbB1LJ or anti-LbB2LJ antibodies were immobilized on protein A-sepharose and immunoprecipitated the NTPDase 1 of 48 kDa and depleted approximately 40% of the phosphohydrolytic activity from detergent-homogenized Lb preparation. Ultrastructural immunocytochemical microscopy identified the NTPDase 1 on the parasite surface and in its subcellular cytoplasmic vesicles, mitochondria, kinetoplast and nucleus. The ATPase and ADPase activities of detergent-homogenized Lb preparation were partially inhibited by anti-LbB1LJ antibody (43-79%), which was more effective than that inhibition (18-47%) by anti-LbB2LJ antibody. In addition, the immune serum anti-LbB1LJ (67%) or anti-LbB2LJ (33%) was cytotoxic, significantly reducing the promastigotes growth in vitro. The results appoint the conserved domain from the L. braziliensis NTPDase as an important target for inhibitor design and the potential application of these biomolecules in experimental protocols of disease control. PMID:22921497

  13. Gold Nanoparticles Cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mironava, Tatsiana

    Over the last two decades gold nanoparticles (AuNPs) have been used for many scientific applications and have attracted attention due to the specific chemical, electronic and optical size dependent properties that make them very promising agents in many fields such as medicine, imagine techniques and electronics. More specifically, biocompatible gold nanoparticles have a huge potential for use as the contrast augmentation agent in X-ray Computed Tomography and Photo Acoustic Tomography for early tumor diagnostic as well these nanoparticles are extensively researched for enhancing the targeted cancer treatment effectiveness such as photo-thermal and radiotherapy. In most biomedical applications biocompatible gold nanoparticles are labeled with specific tumor or other pathology targeting antibodies and used for site specific drug delivery. However, even though gold nanoparticles poses very high level of anti cancer properties, the question of their cytotoxicity ones they are released in normal tissue has to be researched. Moreover, the huge amount of industrially produced gold nanoparticles raises the question of these particles being a health hazard, since the penetration is fairly easy for the "nano" size substances. This study focuses on the effect of AuNPs on a human skin tissue, since it is fall in both categories -- the side effects for biomedical applications and industrial workers and users' exposure during production and handling. Therefore, in the present project, gold nanoparticles stabilized with the biocompatible agent citric acid were generated and characterized by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The cytotoxic effect of AuNPs release to healthy skin tissue was modeled on 3 different cell types: human keratinocytes, human dermal fibroblasts, and human adipose derived stromal (ADS) cells. The AuNPs localization inside the cell was found to be cell type dependent. Overall cytotoxicity was found to be dependent

  14. Cytotoxicity of halogenated graphenes

    NASA Astrophysics Data System (ADS)

    Teo, Wei Zhe; Khim Chng, Elaine Lay; Sofer, Zdeněk; Pumera, Martin

    2013-12-01

    Graphene and its family of derivatives possess unique and remarkable physicochemical properties which make them valuable materials for applications in many areas like electronics, energy storage and biomedicine. In response to the possibility of its large-scale manufacturing as commercial products in the future, an investigation was conducted to determine the cytotoxicity of one particular family of graphene derivatives, the halogenated graphenes, for the first time. Halogenated graphenes were prepared through thermal exfoliation of graphite oxide in gaseous chlorine, bromine or iodine atmospheres to yield chlorine- (TRGO-Cl), bromine- (TRGO-Br) and iodine-doped graphene (TRGO-I) respectively. 24 h exposure of human lung carcinoma epithelial cells (A549) to the three halogenated graphenes and subsequent cell viability assessments using methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8) assays revealed that all the halogenated graphenes examined are rather cytotoxic at the concentrations tested (3.125 μg mL-1 to 200 μg mL-1) and the effects are dose-dependent, with TRGO-Cl reducing the cell viability to as low as 25.7% at the maximum concentration of 200 μg mL-1. Their levels of cytotoxicity can be arranged in the order of TRGO-Cl > TRGO-Br > TRGO-I, and it is suggested that the amount of halogen present in the graphene material is the determining factor for the observed trend. Control experiments were carried out to test for possible nanomaterial-induced interference as a consequence of reaction between the halogenated graphenes and the viability markers (MTT/WST-8 reagent) or binding of the formazan products under cell-free conditions. The data obtained eliminate the probability of significant influence by these interferents as the change in the normalized percentage of formazan formed is relatively small and thorough washings were performed prior to the viability assessments to reduce the amount of halogenated

  15. Sequencing, functional expression and characterization of rat NTPDase6, a nucleoside diphosphatase and novel member of the ecto-nucleoside triphosphate diphosphohydrolase family.

    PubMed

    Braun, N; Fengler, S; Ebeling, C; Servos, J; Zimmermann, H

    2000-11-01

    We have isolated and characterized the cDNA encoding nucleoside triphosphate diphosphohydrolase 6 (NTPDase6), a novel member of the ecto-nucleoside triphosphate diphosphohydrolase family. The rat-brain-derived cDNA has an open reading frame of 1365 bp encoding a protein of 455 amino acid residues, a calculated molecular mass of 49971 Da and a predicted N-terminal hydrophobic sequence. It shares 86% sequence identity with the human CD39L2 sequence and 48% and 51% identity respectively with sequences of the two related human and murine nucleoside diphosphatases (CD39L4, NTPDase5/ER-UDPase). The mRNA was expressed in all tissues investigated, revealing two major transcripts with differing abundances. PCR analysis suggests a single open reading frame. A Myc-His-tagged NTPDase6 was expressed in Chinese hamster ovary (CHO) and PC12 cells for immunological analysis and protein isolation. The protein was contained in membrane fractions of transfected CHO cells and occurred in a soluble form in the cell culture supernatants. NTPDase6 preferentially hydrolysed nucleoside 5'-diphosphates. With different substrates the order of activity was GDP>IDP>UDP,CDP>ADP. Nucleoside 5'-triphosphates were hydrolysed only to a minor extent and no hydrolysis of nucleoside 5'-monophosphates was observed. The enzyme was strongly and equally activated by Ca(2+) and Mg(2+) and had a K(m) for GDP of 211 microM. The immunohistochemical analysis of transfected CHO and PC12 cells suggests that NTPDase6 is associated with the Golgi apparatus and to a small extent also with the plasma membrane. The enzyme might support glycosylation reactions in the Golgi apparatus and, when released from cells, might catalyse the hydrolysis of extracellular nucleotides. PMID:11042118

  16. Evaluation of azathioprine-induced cytotoxicity in an in vitro rat hepatocyte system.

    PubMed

    Al Maruf, Abdullah; Wan, Luke; O'Brien, Peter J

    2014-01-01

    Azathioprine (AZA) is widely used in clinical practice for preventing graft rejection in organ transplantations and various autoimmune and dermatological diseases with documented unpredictable hepatotoxicity. The potential molecular cytotoxic mechanisms of AZA towards isolated rat hepatocytes were investigated in this study using "Accelerated Cytotoxicity Mechanism Screening" techniques. The concentration of AZA required to cause 50% cytotoxicity in 2 hrs at 37°C was found to be 400 μM. A significant increase in AZA-induced cytotoxicity and reactive oxygen species (ROS) formation was observed when glutathione- (GSH-) depleted hepatocytes were used. The addition of N-acetylcysteine decreased cytotoxicity and ROS formation. Xanthine oxidase inhibition by allopurinol decreased AZA-induced cytotoxicity, ROS, and hydrogen peroxide (H2O2) formation and increased % mitochondrial membrane potential (MMP). Addition of N-acetylcysteine and allopurinol together caused nearly complete cytoprotection against AZA-induced hepatocyte death. TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl), a known ROS scavenger and a superoxide dismutase mimic, and antioxidants, like DPPD (N,N'-diphenyl-p-phenylenediamine), Trolox (a water soluble vitamin E analogue), and mesna (2-mercaptoethanesulfonate), also decreased hepatocyte death and ROS formation. Results from this study suggest that AZA-induced cytotoxicity in isolated rat hepatocytes may be partly due to ROS formation and GSH depletion that resulted in oxidative stress and mitochondrial injury. PMID:25101277

  17. Complex regulation of nucleoside transporter expression in epithelial and immune system cells.

    PubMed

    Pastor-Anglada, M; Casado, F J; Valdés, R; Mata, J; García-Manteiga, J; Molina, M

    2001-01-01

    Nucleoside transporters have a variety of functions in the cell, such as the provision of substrates for nucleic acid synthesis and the modulation of purine receptors by determining agonist availability. They also transport a wide range of nucleoside-derived antiviral and anticancer drugs. Most mammalian cells co-express several nucleoside transporter isoforms at the plasma membrane, which are differentially regulated. This paper reviews studies on nucleoside transporter regulation, which has been extensively characterized in the laboratory in several model systems: the hepatocyte, an epithelial cell type, and immune system cells, in particular B cells, which are non-polarized and highly specialized. The hepatocyte co-expresses at least two Na+-dependent nucleoside transporters, CNT1 and CNT2, which are up-regulated during cell proliferation but may undergo selective loss in certain experimental models of hepatocarcinomas. This feature is consistent with evidence that CNT expression also depends on the differentiation status of the hepatocyte. Moreover, substrate availability also modulates CNT expression in epithelial cells, as reported for hepatocytes and jejunum epithelia from rats fed nucleotide-deprived diets. In human B cell lines, CNT and ENT transporters are co-expressed but differentially regulated after B cell activation triggered by cytokines or phorbol esters, as described for murine bone marrow macrophages induced either to activate or to proliferate. The complex regulation of the expression and activity of nucleoside transporters hints at their relevance in cell physiology. PMID:11396615

  18. Cloning, expression, and functional characterization of a Ca(2+)-dependent endoplasmic reticulum nucleoside diphosphatase.

    PubMed

    Failer, Bernd U; Braun, Norbert; Zimmermann, Herbert

    2002-10-01

    We have isolated and characterized the cDNA encoding a Ca(2+)-dependent nucleoside diphosphatase (EC ) related to two secreted ATP- and ADP-hydrolyzing apyrases of the bloodsucking insects, Cimex lectularius and Phlebotomus papatasi. The rat brain-derived cDNA has an open reading frame of 1209 bp encoding a protein of 403 amino acids and a calculated molecular mass of 45.7 kDa. The mRNA was expressed in all tissues investigated, revealing two major transcripts with varying preponderance. The immunohistochemical analysis of the Myc-His-tagged enzyme expressed in Chinese hamster ovary cells revealed its association with the endoplasmic reticulum and also with pre-Golgi intermediates. Ca(2+)-dependent nucleoside diphosphatase is a membrane protein with its catalytic site facing the organelle lumen. It hydrolyzes nucleoside 5'-diphosphates in the order UDP >GDP = IDP >CDP but not ADP. Nucleoside 5'-triphosphates were hydrolyzed to a minor extent, and no hydrolysis of nucleoside 5'-monophosphates was observed. The enzyme was strongly activated by Ca(2+), insensitive to Mg(2+), and had a K(m) for UDP of 216 microm. Ca(2+)-dependent nucleoside diphosphatase may support glycosylation reactions related to quality control in the endoplasmic reticulum. PMID:12167635

  19. CDA directs metabolism of epigenetic nucleosides revealing a therapeutic window in cancer

    PubMed Central

    Zauri, Melania; Berridge, Georgina; Thézénas, Marie-Laëtitia; Pugh, Kathryn M.; Goldin, Robert; Kessler, Benedikt M.; Kriaucionis, Skirmantas

    2015-01-01

    Summary Cells require nucleotides to support DNA replication and to repair damaged DNA. In addition to de novo synthesis, cells recycle nucleotides from the DNA of dying cells or from cellular material ingested through the diet. Salvaged nucleosides come with the complication that they can contain epigenetic modifications. Since epigenetic inheritance of DNA methylation mainly relies on copying of the modification pattern from parental strands1-3, random incorporation of pre-modified bases during replication could have profound implications for epigenome fidelity and yield adverse cellular phenotypes. Although the salvage mechanism of 5-methyl-2′deoxycytidine (5mdC) has been investigated before4-6, currently it remains unknown how cells deal with the recently identified oxidised forms of 5mdC – 5-hydroxymethyl-2′deoxycytidine (5hmdC), 5-formy-2′deoxycytidine (5fdC) and 5-carboxyl-2′deoxycytidine (5cadC)7-10. Here we demonstrate that enzymes of the nucleotide salvage pathway display substrate selectivity, effectively protecting newly synthesized DNA from the incorporation of epigenetically modified forms of cytosine. Thus cell lines and animals can tolerate high doses of these modified cytidines without any deleterious effects on physiology. Interestingly, by screening cancer cell lines for growth defects following exposure to 5hmdC, we unexpectedly identify a subset of cell lines where 5hmdC or 5fdC administration leads to cell lethality. Using genomic approaches we discover that the susceptible cell lines overexpress cytidine deaminase (CDA). CDA converts 5hmdC and 5fdC into variants of uridine that are incorporated into DNA, resulting in accumulation of DNA damage and ultimately, cell death. Our observations extend current knowledge of the nucleotide salvage pathway by revealing the metabolism of oxidised epigenetic bases, and suggest a therapeutic option for cancers, such as pancreatic cancer, that have CDA overexpression and are resistant to treatment

  20. Identification of Ebsulfur Analogues with Broad-Spectrum Antifungal Activity.

    PubMed

    Ngo, Huy X; Shrestha, Sanjib K; Garneau-Tsodikova, Sylvie

    2016-07-19

    Invasive fungal infections are on the rise due to an increased population of critically ill patients as a result of HIV infections, chemotherapies, and organ transplantations. Current antifungal drugs are helpful, but are insufficient in addressing the problem of drug-resistant fungal infections. Thus, there is a growing need for novel antimycotics that are safe and effective. The ebselen scaffold has been evaluated in clinical trials and has been shown to be safe in humans. This makes ebselen an attractive scaffold for facile translation from bench to bedside. We recently reported a library of ebselen-inspired ebsulfur analogues with antibacterial properties, but their antifungal activity has not been characterized. In this study, we repurposed ebselen, ebsulfur, and 32 additional ebsulfur analogues as antifungal agents by evaluating their antifungal activity against a panel of 13 clinically relevant fungal strains. The effect of induction of reactive oxygen species (ROS) by three of these compounds was evaluated. Their hemolytic and cytotoxicity activities were also determined using mouse erythrocytes and mammalian cells. The MIC values of these compounds were found to be in the range of 0.02-12.5 μg mL(-1) against the fungal strains tested. Notably, yeast cells treated with our compounds showed an accumulation of ROS, which may further contribute to the growth-inhibitory effect against fungi. This study provides new lead compounds for the development of antimycotic agents. PMID:27334363

  1. FUNCTION GENERATOR FOR ANALOGUE COMPUTERS

    DOEpatents

    Skramstad, H.K.; Wright, J.H.; Taback, L.

    1961-12-12

    An improved analogue computer is designed which can be used to determine the final ground position of radioactive fallout particles in an atomic cloud. The computer determines the fallout pattern on the basis of known wind velocity and direction at various altitudes, and intensity of radioactivity in the mushroom cloud as a function of particle size and initial height in the cloud. The output is then displayed on a cathode-ray tube so that the average or total luminance of the tube screen at any point represents the intensity of radioactive fallout at the geographical location represented by that point. (AEC)

  2. Ecstasy analogues found in cacti.

    PubMed

    Bruhn, Jan G; El-Seedi, Hesham R; Stephanson, Nikolai; Beck, Olof; Shulgin, Alexander T

    2008-06-01

    Human interest in psychoactive phenethylamines is known from the use of mescaline-containing cacti and designer drugs such as Ecstasy. From the alkaloid composition of cacti we hypothesized that substances resembling Ecstasy might occur naturally. In this article we show that lophophine, homopiperonylamine and lobivine are new minor constituents of two cactus species, Lophophora williamsii (peyote) and Trichocereus pachanoi (San Pedro). This is the first report of putatively psychoactive phenethylamines besides mescaline in these cacti. A search for further biosynthetic analogues may provide new insights into the structure-activity relationships of mescaline. An intriguing question is whether the new natural compounds can be called "designer drugs." PMID:18720674

  3. Kinetics and mechanism of the acid-catalyzed hydrolysis of a hypermodified nucleoside wyosine and its 5'-monophosphate.

    PubMed Central

    Golankiewicz, B; Zielonacka-Lis, E; Folkman, W

    1985-01-01

    The rates of acid-catalyzed hydrolysis of a hypermodified nucleoside, wyosine and its 5'-monophosphate were determined at various pH, temperature and buffer concentrations. The results show that despite distinct differences in structure and the glycosyl bond stability, the hydrolysis of wyosine proceeds via cleavage of the C-N bond by A-1 mechanism, analogously to simple nucleosides. Unlike majority of other monophosphates studied so far, wyosine 5'-monophosphate is not more stable than respective nucleoside. PMID:4000960

  4. Human Immunodeficiency Virus Protease Inhibitors Interact with ATP Binding Cassette Transporter 4/Multidrug Resistance Protein 4: A Basis for Unanticipated Enhanced Cytotoxicity

    PubMed Central

    Fukuda, Yu; Takenaka, Kazumasa; Sparreboom, Alex; Cheepala, Satish B.; Wu, Chung-Pu; Ekins, Sean; Ambudkar, Suresh V.

    2013-01-01

    Human immunodeficiency virus (HIV) pharmacotherapy, by combining different drug classes such as nucleoside analogs and HIV protease inhibitors (PIs), has increased HIV-patient life expectancy. Consequently, among these patients, an increase in non-HIV–associated cancers has produced a patient cohort requiring both HIV and cancer chemotherapy. We hypothesized that multidrug resistance protein 4/ATP binding cassette transporter 4 (MRP4/ABCC4), a widely expressed transporter of nucleoside-based antiviral medications as well as cancer therapeutics might interact with PIs. Among the PIs evaluated (nelfinavir, ritonavir, amprenavir, saquinavir, and indinavir), only nelfinavir both effectively stimulated MRP4 ATPase activity and inhibited substrate-stimulated ATPase activity. Saos2 and human embryonic kidney 293 cells engineered to overexpress MRP4 were then used to assess transport and cytotoxicity. MRP4 expression reduced intracellular accumulation of nelfinavir and consequently conferred survival advantage to nelfinavir cytotoxicity. Nelfinavir blocked Mrp4-mediated export, which is consistent with its ability to increase the sensitivity of MRP4-expressing cells to methotrexate. In contrast, targeted inactivation of Abcc4/Mrp4 in mouse cells specifically enhanced nelfinavir and 9-(2-phosphonylmethoxyethyl) adenine cytotoxicity. These results suggest that nelfinavir is both an inhibitor and substrate of MRP4. Because nelfinavir is a new MRP4/ABCC4 substrate, we developed a MRP4/ABCC4 pharmacophore model, which showed that the nelfinavir binding site is shared with chemotherapeutic substrates such as adefovir and methotrexate. Our studies reveal, for the first time, that nelfinavir, a potent and cytotoxic PI, is both a substrate and inhibitor of MRP4. These findings suggest that HIV-infected cancer patients receiving nelfinavir might experience both enhanced antitumor efficacy and unexpected adverse toxicity given the role of MRP4/ABCC4 in exporting nucleoside

  5. Synthesis and biological evaluation of phosphoramidate prodrugs of two analogues of 2-deoxy-d-ribose-1-phosphate directed to the discovery of two carbasugars as new potential anti-HIV leads.

    PubMed

    Hamon, Nadège; Slusarczyk, Magdalena; Serpi, Michaela; Balzarini, Jan; McGuigan, Christopher

    2015-02-15

    2-Deoxy-α-d-ribose-1-phosphate is of great interest as it is involved in the biosynthesis and/or catabolic degradation of several nucleoside analogues of biological and therapeutic relevance. However due to the lack of a stabilising group at its 2-position, it is difficult to synthesize stable prodrugs of this compound. In order to overcome this lack of stability, the synthesis of carbasugar analogues of 2-deoxyribose-1-phosphate was envisioned. Herein the preparation of a series of prodrugs of two carbocyclic analogues of 2-deoxyribose-1-phosphate using the phosphoramidate ProTide technology, along with their biological evaluation against HIV and cancer cell proliferation, is reported. PMID:25616343

  6. Triple nucleoside reverse transcriptase inhibitor therapy in children.

    PubMed

    Handforth, Jennifer; Sharland, Mike

    2004-01-01

    Much of the success attributed to HIV therapy in the last few years has resulted from improved ways of using existing drugs in combination therapy regimens. The availability of new, more potent drugs such as protease inhibitors and more accurate viral load tests to aid decisions to start or change treatment has also contributed to the success. Published recommendations for pediatric HIV therapy, generated by a panel of experts and specialists, are readily available and regularly updated. Preferred regimens of 'potent' therapy (referred to as highly active antiretroviral therapy, or HAART) currently consist of two nucleoside reverse transcriptase inhibitors (NRTIs) combined with either a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor. More intense four-drug regimens using an NNRTI or a second protease inhibitor as a fourth drug are being evaluated. Problems with HAART include: unpalatable drug formulations and adverse effects, coupled with lack of data on the pharmacokinetics, efficacy, and safety of various drug combinations. Adherence is a major factor influencing the efficacy and outcome of antiretroviral therapy. Many children cannot adhere to complex multidrug regimens, which cause virologic failure, despite excellent CD4+ cell count responses. This means a rapid progression through the limited number of treatment regimens available. Simpler regimens such as those containing three NRTIs have been proposed as a method of treatment that will allow suppression of the virus, yet circumvent many of the problems previously mentioned. An additional benefit would be the preservation of antiretroviral drugs from other classes for future treatment options if required. The major advantages of triple NRTI regimens are the simplicity of the regimen, good tolerability, few drug-drug interactions, and infrequent adverse effects coupled with a low pill burden. However, abacavir hypersensitivity remains a major problem. Up to 3% of patients may

  7. The Valles natural analogue project

    SciTech Connect

    Stockman, H.; Krumhansl, J.; Ho, C.; McConnell, V.

    1994-12-01

    The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a highlevel waste repository. The analogue site is located in the Valles Caldera in New Mexico, where a massive obsidian flow filled a paleocanyon in the Battleship Rock tuff. The obsidian flow provided a heat source, analogous to waste panels or an igneous intrusion in a repository, and caused evaporation and migration of water. The tuff and obsidian samples were analyzed for major and trace elements and mineralogy by INAA, XRF, X-ray diffraction; and scanning electron microscopy and electron microprobe. Samples were also analyzed for D/H and {sup 39}Ar/{sup 4O} isotopic composition. Overall,the effects of the heating event seem to have been slight and limited to the tuff nearest the contact. There is some evidence of devitrification and migration of volatiles in the tuff within 10 meters of the contact, but variations in major and trace element chemistry are small and difficult to distinguish from the natural (pre-heating) variability of the rocks.

  8. A Computational Study of Expanded Heterocyclic Nucleosides in DNA

    PubMed Central

    O'Daniel, Peter I.; Jefferson, Malcolm; Wiest, Olaf; Seley-Radtke, Katherine L.

    2008-01-01

    The first molecular dynamics study of a series of heterospacer-expanded tricyclic bases in DNA using modified force field parameters in AMBER is detailed. The expanded purine nucleoside monomers have been designed to probe the effects of a heteroaromatic spacer ring on the structure, function, and dynamics of the DNA helix. The heterobase scaffold has been expanded with a furan, pyrrole, or thiophene spacer ring. This structural modification increases the polarizability of the bases and provides an additional hydrogen bond donor with the amine hydrogen of the pyrrole ring or hydrogen bond acceptor with the furan or thiophene ring free electron pairs. The polarizability of the expanded bases were determined by AM1 calculations and the results of the MD simulations of 20-mers predict that the modified curvature of the expanded base leads to a much larger major groove, while the effect on the minor groove is negligible. Overall, the structure resembles A-DNA. MD simulations of 10-mers suggest that the balance between base pairing vs. base stacking and intercalation can be shifted towards the latter due to the increased surface area and polariz-ability of the expanded bases. PMID:18808194

  9. Interaction of purine bases and nucleosides with serum albumin

    NASA Astrophysics Data System (ADS)

    Sułkowska, A.; Michnik, A.

    1997-06-01

    The proton NMR spectra of alkyl derivatives of adenine and adenosine have been studied. High-resolution (400 MHz) proton spectra were recorded at 300 K at increasing concentrations of serum albumin. The dependence of the chemical shifts and the line width of the individual spectral lines on the protein concentration provides some detailed information about the nature of the complexes between the purine derivatives and albumin. Comparison of data for the methylated and non-methylated purine bases and nucleosides indicates the formation of non-specific complexes with serum albumin. However, the presence of the ethyl group in 8-ethyl-9 N-methyladenine means that in the adenine derivative-serum albumin complex the ethyl chain preserves its dominant role in binding. An advantage of our model is that the π-π interaction between the adenine ring and the amino acids of the protein can be replaced by hydrophobic interaction in the case of complexation of the ethyl adenine derivative.

  10. DNA nucleoside composition and methylation in several species of microalgae

    SciTech Connect

    Jarvis, E.E.; Dunahay, T.G.; Brown, L.M. )

    1992-06-01

    Total DNA was isolated from 10 species of microalgae, including representatives of the Chlorophyceae (Chlorella ellipsoidea, Chlamydomonas reinhardtii, and Monoraphidium minutum), Bacillariophyceae (Cyclotella cryptica, Navicula saprophila, Nitzschia pusilla, and Phaeodactylum tricornutum), Charophyceae (Stichococcus sp.), Dinophyceae (Crypthecodinium cohnii), and Prasinophyceae (Tetraselmis suecica). Control samples of Escherichia coli and calf thymus DNA were also analyzed. The nucleoside base composition of each DNA sample was determined by reversed-phase high performance liquid chromatography. All samples contained 5-methyldeoxycytidine, although at widely varying levels. In M. minutum, about one-third of the cytidine residues were methylated. Restriction analysis supported this high degree of methylation in M. minutum and suggested that methylation is biased toward 5[prime]-CG dinucleotides. The guanosine + cytosine (GC) contents of the green algae were, with the exception of Stichococcus sp., consistently higher than those of the diatoms. Monoraphidium minutum exhibited an extremely high GC content of 71%. Such a value is rare among eukaryotic organisms and might indicate an unusual codon usage. This work is important for developing strategies for transformation and gene cloning in these algae. 46 refs., 1 fig., 2 tabs.

  11. Fluorescent pyrimidopyrimidoindole nucleosides: control of photophysical characterizations by substituent effects.

    PubMed

    Mizuta, Masahiro; Seio, Kohji; Miyata, Kenichi; Sekine, Mitsuo

    2007-07-01

    10-(2-Deoxy-beta-D-ribofuranosyl)pyrimido[4',5':4,5]pyrimido[1,6-a]indole-6,9(7H)-dione (dCPPI) and its derivatives were synthesized via the Suzuki-Miyaura coupling reaction of 5-iododeoxycytidine with 5-substituted N-Boc-indole-2-borates and characterized by UV-vis and fluorescence spectroscopy. The new fluorescent nucleosides showed rather large Stokes shifts (116-139 nm) in an aqueous buffer. The fluorescent intensities were dependent on the nature of the substituents on the indole rings. The electron-withdrawing groups increased the fluorescent intensity while the electron-donating groups having lone pairs decreased it. Among the substituted dCPPI derivatives tested, the trimethylammonium derivative of dCPPI was found to emit the brightest fluorescent light. The solvatochromism of dCPPI and its derivatives was also studied. Some of the dCPPI derivatives showed interesting solvent-dependent fluorescence enhancement and could be useful as new fluorescent structural probes for nucleic acids. The Lippert-Mataga analyses of the Stokes shift were also carried out to obtain estimated values of the dipole moment of the excited states of some of the derivatives. PMID:17555352

  12. Inhibition of topoisomerase II α activity and induction of apoptosis in mammalian cells by semi-synthetic andrographolide analogues.

    PubMed

    Nateewattana, Jintapat; Saeeng, Rungnapha; Kasemsook, Sakkasem; Suksen, Kanoknetr; Dutta, Suman; Jariyawat, Surawat; Chairoungdua, Arthit; Suksamrarn, Apichart; Piyachaturawat, Pawinee

    2013-04-01

    Topoisomerase II α enzyme plays a critical role in DNA replication process. It controls the topologic states of DNA during transcription and is essential for cell proliferation. Human DNA topoisomerase II α (hTopo II α) is a promising chemotherapeutic target for anticancer agents against a variety of cancer types. In the present study, andrographolide and its structurally modified analogues were investigated for their inhibitory activities on hTopo II α enzyme. Five out of nine andrographolide analogues potently reduced hTopo II α activity and inhibited cell proliferation in four mammalian cell lines (Hela, CHO, BCA-1 and HepG2 cells). IC50 values for cytotoxicity of analogues 3A.1, 3A.2, 3A.3, 1B and 2C were 4 to 7 μM. Structure-activity relationship studies revealed that both core structure of andrographolide and silicon based molecule of functional group were important for the inhibition of hTopo II α activity whereas position C-19 of analogues was required for anti-proliferation. In addition, the analogue 2C at 10 μM concentration inhibited hTopo II α, and induced apoptosis with nuclear fragmentation and formation of apoptotic bodies in HepG2 cells. The analogue 2C may, therefore, have a therapeutic potential as effective anticancer agent targeting the hTopo II α functions. PMID:22899371

  13. Allelic isoforms of the H+/nucleoside co-transporter (CaCNT) from Candida albicans reveal separate high- and low-affinity transport systems for nucleosides.

    PubMed

    Slugoski, Melissa D; Loewen, Shaun K; Ng, Amy M L; Baldwin, Stephen A; Cass, Carol E; Young, James D

    2004-11-01

    Contigs 19-10196 and 19-20196 of the Stanford Candida albicans genome sequence databank encode two putative allelic isoforms of C. albicans CaCNT, a recently characterized 608 amino acid residue H+-coupled fungal member of the CNT family of concentrative nucleoside transport proteins. The single Ser/Gly difference between CaCNT/19-20196 and CaCNT occurs at position 328 in putative TM 7, and corresponds to a Ser/Gly substitution previously shown to contribute to the contrasting pyrimidine and purine nucleoside selectivities of human (h) and rat (r) Na+-dependent CNT1 and CNT2. CaCNT/19-10196 differs from CaCNT by four amino acids, but has Gly at position 328. These new proteins were recreated by site-directed mutagenesis of CaCNT and characterized functionally by heterologous expression in Xenopus laevis oocytes. In marked contrast to h/rCNT1/2, both CaCNT/19-10196 and CaCNT/19-20196 exhibited permeant selectivities for purine nucleosides (adenosine, guanosine and inosine) and uridine similar to that of CaCNT. However, although H+-coupled, CaCNT/19-20196 exhibited a approximately 10-fold higher apparent Km for uridine than either CaCNT or CaCNT/19-10196. CaCNT/19-20196 also exhibited a low apparent affinity for inosine. We conclude that the three proteins correspond to high-affinity (CaCNT, CaCNT/19-10196) and low-affinity (CaCNT/19-20196) allelic isoforms of the C. albicans CNT nucleoside transporter. This is the first example of a single amino acid residue substitution altering a CNT protein's overall apparent affinity for nucleosides. PMID:15543539

  14. CO2 Capture with Enzyme Synthetic Analogue

    SciTech Connect

    Cordatos, Harry

    2010-11-08

    Overview of an ongoing, 2 year research project partially funded by APRA-E to create a novel, synthetic analogue of carbonic anhydrase and incorporate it into a membrane for removal of CO2 from flue gas in coal power plants. Mechanism background, preliminary feasibility study results, molecular modeling of analogue-CO2 interaction, and program timeline are provided.

  15. Crucial roles of thymidine kinase 1 and deoxyUTPase in incorporating the antineoplastic nucleosides trifluridine and 2'-deoxy-5-fluorouridine into DNA.

    PubMed

    Sakamoto, Kazuki; Yokogawa, Tatsushi; Ueno, Hiroyuki; Oguchi, Kei; Kazuno, Hiromi; Ishida, Keiji; Tanaka, Nozomu; Osada, Akiko; Yamada, Yukari; Okabe, Hiroyuki; Matsuo, Kenichi

    2015-01-01

    Trifluridine (FTD) and 2'-deoxy-5-fluorouridine (FdUrd), a derivative of 5-fluorouracil (5-FU), are antitumor agents that inhibit thymidylate synthase activity and their nucleotides are incorporated into DNA. However, it is evident that several differences occur in the underlying antitumor mechanisms associated with these nucleoside analogues. Recently, TAS-102 (composed of FTD and tipiracil hydrochloride, TPI) was shown to prolong the survival of patients with colorectal cancer who received a median of 2 prior therapies, including 5-FU. TAS-102 was recently approved for clinical use in Japan. These data suggest that the antitumor activities of TAS-102 and 5-FU proceed via different mechanisms. Thus, we analyzed their properties in terms of thymidine salvage pathway utilization, involving membrane transporters, a nucleoside kinase, a nucleotide-dephosphorylating enzyme, and DNA polymerase α. FTD incorporated into DNA with higher efficiency than FdUrd did. Both FTD and FdUrd were transported into cells by ENT1 and ENT2 and were phosphorylated by thymidine kinase 1, which showed a higher catalytic activity for FTD than for FdUrd. deoxyUTPase (DUT) did not recognize dTTP and FTD-triphosphate (F3dTTP), whereas deoxyuridine-triphosphate (dUTP) and FdUrd-triphosphate (FdUTP) were efficiently degraded by DUT. DNA polymerase α incorporated both F3dTTP and FdUTP into DNA at sites aligned with adenine on the opposite strand. FTD-treated cells showed differing nuclear morphologies compared to FdUrd-treated cells. These findings indicate that FTD and FdUrd are incorporated into DNA with different efficiencies due to differences in the substrate specificities of TK1 and DUT, causing abundant FTD incorporation into DNA. PMID:25901475

  16. Crucial roles of thymidine kinase 1 and deoxyUTPase in incorporating the antineoplastic nucleosides trifluridine and 2′-deoxy-5-fluorouridine into DNA

    PubMed Central

    SAKAMOTO, KAZUKI; YOKOGAWA, TATSUSHI; UENO, HIROYUKI; OGUCHI, KEI; KAZUNO, HIROMI; ISHIDA, KEIJI; TANAKA, NOZOMU; OSADA, AKIKO; YAMADA, YUKARI; OKABE, HIROYUKI; MATSUO, KENICHI

    2015-01-01

    Trifluridine (FTD) and 2′-deoxy-5-fluorouridine (FdUrd), a derivative of 5-fluorouracil (5-FU), are antitumor agents that inhibit thymidylate synthase activity and their nucleotides are incorporated into DNA. However, it is evident that several differences occur in the underlying antitumor mechanisms associated with these nucleoside analogues. Recently, TAS-102 (composed of FTD and tipiracil hydrochloride, TPI) was shown to prolong the survival of patients with colorectal cancer who received a median of 2 prior therapies, including 5-FU. TAS-102 was recently approved for clinical use in Japan. These data suggest that the antitumor activities of TAS-102 and 5-FU proceed via different mechanisms. Thus, we analyzed their properties in terms of thymidine salvage pathway utilization, involving membrane transporters, a nucleoside kinase, a nucleotide-dephosphorylating enzyme, and DNA polymerase α. FTD incorporated into DNA with higher efficiency than FdUrd did. Both FTD and FdUrd were transported into cells by ENT1 and ENT2 and were phosphorylated by thymidine kinase 1, which showed a higher catalytic activity for FTD than for FdUrd. deoxyUTPase (DUT) did not recognize dTTP and FTD-triphosphate (F3dTTP), whereas deoxyuridine-triphosphate (dUTP) and FdUrd-triphosphate (FdUTP) were efficiently degraded by DUT. DNA polymerase α incorporated both F3dTTP and FdUTP into DNA at sites aligned with adenine on the opposite strand. FTD-treated cells showed differing nuclear morphologies compared to FdUrd-treated cells. These findings indicate that FTD and FdUrd are incorporated into DNA with different efficiencies due to differences in the substrate specificities of TK1 and DUT, causing abundant FTD incorporation into DNA. PMID:25901475

  17. Cytotoxicity of Hymenocallis expansa alkaloids.

    PubMed

    Antoun, M D; Mendoza, N T; Ríos, Y R; Proctor, G R; Wickramaratne, D B; Pezzuto, J M; Kinghorn, A D

    1993-08-01

    From the bulbs and leaves of Hymenocallis expansa (Amaryllidaceae), three alkaloid constituents were identified: (+)-tazettine, (+)-hippeastrine, and (-)-haemanthidine. These alkaloids demonstrated significant cytotoxicity when tested against a panel of human and murine tumor cell lines. PMID:8229020

  18. 5-Nitroindole as an universal base analogue.

    PubMed Central

    Loakes, D; Brown, D M

    1994-01-01

    4-, 5- and 6-Nitroindole have been investigated and compared with 3-nitropyrrole as universal bases in oligodeoxynucleotides. Of these the 5-nitroindole derivative was found to be superior giving higher duplex stability, and behaving indiscriminately towards each of the four natural bases in duplex melting experiments. 3-Nitropyrrole, whilst not discriminating between the natural bases, was found to lead to considerable destabilisation of the duplexes, particularly when multiple substitutions were made, in contrast to the 5-nitroindole nucleoside. PMID:7937128

  19. Binding Strength of Nucleobases and Nucleosides on Silver Nanoparticles Probed by a Colorimetric Method.

    PubMed

    Yu, Lu; Li, Na

    2016-06-01

    Because of their unique and tunable properties, oligonucleotide-functionalized noble metal nanoparticles have provided a versatile platform for various engineering and biomedical applications. The vast majority of such applications were demonstrated with gold nanoparticles (AuNPs) while only a few were demonstrated with sliver nanoparticles (AgNPs). This is largely due to the lack of robust protocols to functionalize AgNPs with thiol-modified oligonucleotides. Previous studies have revealed strong interactions between nucleobases and AgNPs. This could enable an alternative way to functionalize AgNPs with non-thiolated oligonucleotides. However, there is no quantitative study on the interaction strengths between AgNPs and oligonucleotides. Several methods have been used for quantitative evaluation of the interaction strengths between AuNPs and oligonucleotides. These methods often require specialized equipment that might not be widely accessible or rely on labor-intensive procedures to obtain the adsorption isotherms. Herein, we developed a colorimetric method, as a simple and high-throughput alternative of existing methods, to quantify the binding strength between AgNPs and nucleobases/nucleosides. In this colorimetric method, concentration-dependent destabilizing effects of nucleobase/nucleoside adsorption on AgNPs are utilized to indirectly quantify the amount of nucleobases/nucleosides adsorbed on AgNPs, thus deriving the binding strength between AgNPs and nucleobases/nucleosides. First, the concentration-dependent AgNP aggregation kinetics in the presence of nucleobases/nucleosides were systematically investigated. Then, this colorimetric method was used to determine the binding strengths between AgNPs and various DNA/RNA nucleobases/nucleosides. It was found that the ranking of interaction strengths between AgNPs and DNA/RNA nucleosides (dC < dT < dA, rC < rU < rA) is generally agreed with that between AgNPs and corresponding nucleobases (C < T < U < A). This

  20. Cytotoxic activity of Staphylococcus hyicus.

    PubMed

    Allaker, R P; Whitlock, M; Lloyd, D H

    1991-01-01

    Culture supernatants from a number of Staphylococcus hyicus strains caused toxic effects to both murine fibroblast and porcine keratinocyte cells in culture. The extent of cytotoxicity was shown to differ between strains and may provide an indication of strain virulence. Purification of cytotoxic activity produced by S. hyicus (strain P119) using preparative isoelectric-focussing demonstrated it to be cytolytic, haemolytic and non-proteolytic. The cytotoxin demonstrates certain properties in common with the delta haemolysin of Staphylococcus aureus. PMID:2024438

  1. Fully analogue photonic reservoir computer.

    PubMed

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-01-01

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers. PMID:26935166

  2. An analogue study of intrusions.

    PubMed

    Laposa, Judith M; Alden, Lynn E

    2006-07-01

    According to cognitive theorists, intrusive trauma memories have their origin in how information during the event is processed. Two studies investigated functional cognitive strategies during medical crises that might protect against intrusions. In Study 1, interviews with health-care professionals were used to identify cognitive strategies judged to be effective in controlling emotions and dealing with medical crises. Study 2 systematically manipulated the use of those strategies in a trauma analogue film paradigm. Experimental participants reported fewer intrusions, and less fear and avoidance of film-related stimuli during the subsequent week than controls. The manipulation did not affect anxiety during the film or memory disorganization. Implications for cognitive theories of intrusion development are discussed. PMID:16125135

  3. Fully analogue photonic reservoir computer

    PubMed Central

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-01-01

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers. PMID:26935166

  4. Saturable Hepatic Extraction of Gemcitabine Involves Biphasic Uptake Mediated by Nucleoside Transporters Equilibrative Nucleoside Transporter 1 and 2.

    PubMed

    Shimada, Takuya; Nakanishi, Takeo; Tajima, Hidehiro; Yamazaki, Maiko; Yokono, Rina; Takabayashi, Makiko; Shimada, Tsutomu; Sawamoto, Kazuki; Miyamoto, Ken-Ichi; Kitagawa, Hirohisa; Ohta, Tetsuo; Tamai, Ikumi; Sai, Yoshimichi

    2015-09-01

    Hepatic arterial infusion (HAI) chemotherapy with gemcitabine (GEM) is expected to be more effective and safer method to treat hepatic metastasis of pancreatic cancer compared with intravenous administration, because it affords higher tumor exposure with lower systemic exposure. Thus, a key issue for dose selection is the saturability of hepatic uptake of GEM. Therefore, we investigated GEM uptake in rat and human isolated hepatocytes. Hepatic GEM uptake involved high- and low-affinity saturable components with Km values of micromolar and millimolar order, respectively. The uptake was inhibited concentration dependently by S-(4-nitrobenzyl)-6-thioinosine (NBMPR) and was sodium-ion-independent, suggesting a contribution of equilibrative nucleoside transporters (ENTs). The concentration dependence of uptake in the presence of 0.1 μM NBMPR showed a single low-affinity binding site. Therefore, the high- and low-affinity sites correspond to ENT1 and ENT2, respectively. Our results indicate hepatic extraction of GEM is predominantly mediated by the low-affinity site (hENT2), and at clinically relevant hepatic concentrations of GEM, hENT2-mediated uptake would not be completely saturated. This is critical for HAI, because saturation of hepatic uptake would result in a marked increase of GEM concentration in the peripheral circulation, abrogating the advantage of HAI over intravenous administration in terms of severe adverse events. PMID:26037416

  5. Spectrum of activity and mechanisms of resistance of various nucleoside derivatives against gammaherpesviruses.

    PubMed

    Coen, Natacha; Duraffour, Sophie; Topalis, Dimitri; Snoeck, Robert; Andrei, Graciela

    2014-12-01

    The susceptibilities of gammaherpesviruses, including Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV), and animal rhadinoviruses, to various nucleoside analogs was investigated in this work. Besides examining the antiviral activities and modes of action of antivirals currently marketed for the treatment of alpha- and/or betaherpesvirus infections (including acyclovir, ganciclovir, penciclovir, foscarnet, and brivudin), we also investigated the structure-activity relationship of various 5-substituted uridine and cytidine molecules. The antiviral efficacy of nucleoside derivatives bearing substitutions at the 5 position was decreased if the bromovinyl was replaced by chlorovinyl. 1-β-D-Arabinofuranosyl-(E)-5-(2-bromovinyl)uracil (BVaraU), a nucleoside with an arabinose configuration of the sugar ring, exhibited no inhibitory effect against rhadinoviruses but was active against EBV. On the other hand, the fluoroarabinose cytidine analog 2'-fluoro-5-iodo-aracytosine (FIAC) showed high selectivity indices against gammaherpesviruses that were comparable to those of brivudin. Additionally, we selected brivudin- and acyclovir-resistant rhadinoviruses in vitro and characterized them by phenotypic and genotypic (i.e., sequencing of the viral thymidine kinase, protein kinase, and DNA polymerase) analysis. Here, we reveal key amino acids in these enzymes that play an important role in substrate recognition. Our data on drug susceptibility profiles of the different animal gammaherpesvirus mutants highlighted cross-resistance patterns and indicated that pyrimidine nucleoside derivatives are phosphorylated by the viral thymidine kinase and purine nucleosides are preferentially activated by the gammaherpesvirus protein kinase. PMID:25267682

  6. Cloning and functional expression of a complementary DNA encoding a mammalian nucleoside transport protein.

    PubMed

    Huang, Q Q; Yao, S Y; Ritzel, M W; Paterson, A R; Cass, C E; Young, J D

    1994-07-01

    Expression screening in Xenopus oocytes was used to isolate a cDNA from rat jejunal epithelium encoding a Na(+)-dependent nucleoside transport protein (named cNT1). The cDNA sequence of cNT1 predicts a protein of 648 amino acids (relative molecular mass 71,000) with 14 potential transmembrane domains. Data base searches indicate significant sequence similarity to the NUPC proton/nucleoside symporter of Escherichia coli. There is no sequence similarity between cNT1 and proteins of mammalian origin. Functionally, cNT1 exhibited the transport characteristics of the nucleoside transport system cit (selective for pyrimidine nucleosides and adenosine) and accepted both 3'-azido-3'-deoxythymidine (AZT) and 2',3'-dideoxycytidine (ddC) as permeants (Km = 0.49 and 0.51 mM, respectively). The demonstration of transport of AZT by cNT1 expressed in Xenopus oocytes provides the first direct evidence that AZT enters cells by transporter-mediated processes, as well as by passive diffusion. Consistent with the tissue distribution of system cit transport activity, transcripts for cNT1 were detected in kidney as well as jejunum. cNT1 therefore belongs to a potential new gene family and may be involved in the intestinal absorption and renal handling of pyrimidine nucleoside analogs used to treat acquired immunodeficiency syndrome (AIDS). PMID:8027026

  7. Supramolecular polymerization of a prebiotic nucleoside provides insights into the creation of sequence-controlled polymers

    DOE PAGESBeta

    Wang, Jun; Bonnesen, Peter V; Rangel, E.; Vallejo, E.; Sanchez-Castillo, Ariadna; Cleaves, II, H. James; Baddorf, Arthur P; Sumpter, Bobby G; Pan, Minghu; Maksymovych, Petro; et al

    2016-01-04

    The self-assembly of a nucleoside on Au(111) was studied to ascertain whether polymerization on well-defined substrates constitutes a promising approach for making sequence-controlled polymers. Scanning tunneling microscopy and density functional theory were used to investigate the self-assembly on Au(111) of (RS)-N9-(2,3-dihydroxypropyl)adenine (DHPA), a plausibly prebiotic nucleoside analog of adenosine. It is found that DHPA molecules self-assemble into a hydrogen-bonded polymer that grows almost exclusively along the herringbone reconstruction pattern, has a two component sequence that is repeated over hundreds of nanometers, and is erasable with electron-induced excitation. Although the sequence is simple, more complicated ones are envisioned if two ormore » more nucleoside types are combined. Because polymerization occurs on a substrate in a dry environment, the success of each combination can be gauged with high-resolution imaging and accurate modeling techniques. The resulting characteristics make nucleoside self-assembly on a substrate an attractive approach for designing sequence-controlled polymers. Moreover, by choosing plausibly prebiotic nucleosides, insights may be provided into how nature created the first sequence-controlled polymers capable of storing information. Such insights, in turn, can inspire new ways of synthesizing sequence-controlled polymers.« less

  8. Supramolecular polymerization of a prebiotic nucleoside provides insights into the creation of sequence-controlled polymers

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Bonnesen, Peter V.; Rangel, E.; Vallejo, E.; Sanchez-Castillo, Ariadna; James Cleaves, H., II; Baddorf, Arthur P.; Sumpter, Bobby G.; Pan, Minghu; Maksymovych, Petro; Fuentes-Cabrera, Miguel

    2016-01-01

    Self-assembly of a nucleoside on Au(111) was studied to ascertain whether polymerization on well-defined substrates constitutes a promising approach for making sequence-controlled polymers. Scanning tunneling microscopy and density functional theory were used to investigate the self-assembly on Au(111) of (RS)-N9-(2,3-dihydroxypropyl)adenine (DHPA), a plausibly prebiotic nucleoside analog of adenosine. It is found that DHPA molecules self-assemble into a hydrogen-bonded polymer that grows almost exclusively along the herringbone reconstruction pattern, has a two component sequence that is repeated over hundreds of nanometers, and is erasable with electron-induced excitation. Although the sequence is simple, more complicated ones are envisioned if two or more nucleoside types are combined. Because polymerization occurs on a substrate in a dry environment, the success of each combination can be gauged with high-resolution imaging and accurate modeling techniques. These characteristics make nucleoside self-assembly on a substrate an attractive approach for designing sequence-controlled polymers. Further, by choosing plausibly prebiotic nucleosides, insights may be provided into how nature created the first sequence-controlled polymers capable of storing information. Such insights, in turn, can inspire new ways of synthesizing sequence-controlled polymers.

  9. Supramolecular polymerization of a prebiotic nucleoside provides insights into the creation of sequence-controlled polymers

    PubMed Central

    Wang, Jun; Bonnesen, Peter V.; Rangel, E.; Vallejo, E.; Sanchez-Castillo, Ariadna; James Cleaves II, H.; Baddorf, Arthur P.; Sumpter, Bobby G.; Pan, Minghu; Maksymovych, Petro; Fuentes-Cabrera, Miguel

    2016-01-01

    Self-assembly of a nucleoside on Au(111) was studied to ascertain whether polymerization on well-defined substrates constitutes a promising approach for making sequence-controlled polymers. Scanning tunneling microscopy and density functional theory were used to investigate the self-assembly on Au(111) of (RS)-N9-(2,3-dihydroxypropyl)adenine (DHPA), a plausibly prebiotic nucleoside analog of adenosine. It is found that DHPA molecules self-assemble into a hydrogen-bonded polymer that grows almost exclusively along the herringbone reconstruction pattern, has a two component sequence that is repeated over hundreds of nanometers, and is erasable with electron-induced excitation. Although the sequence is simple, more complicated ones are envisioned if two or more nucleoside types are combined. Because polymerization occurs on a substrate in a dry environment, the success of each combination can be gauged with high-resolution imaging and accurate modeling techniques. These characteristics make nucleoside self-assembly on a substrate an attractive approach for designing sequence-controlled polymers. Further, by choosing plausibly prebiotic nucleosides, insights may be provided into how nature created the first sequence-controlled polymers capable of storing information. Such insights, in turn, can inspire new ways of synthesizing sequence-controlled polymers. PMID:26725380

  10. Evaluating the reproducibility of quantifying modified nucleosides from ribonucleic acids by LC-UV-MS.

    PubMed

    Russell, Susan P; Limbach, Patrick A

    2013-04-01

    Post-transcriptional chemical covalent modification of adenosine, guanosine, uridine and cytidine occurs frequently in all types of ribonucleic acids (RNAs). In ribosomal RNA (rRNA) and transfer RNA (tRNA) these modifications make important contributions to RNA structure and stability and to the accuracy and efficiency of protein translation. The functional dynamics, synergistic nature and regulatory roles of these posttranscriptional nucleoside modifications within the cell are not well characterized. These modifications are present at very low levels and isolation of individual nucleosides for analysis requires a complex multi-step approach. The focus of this study is to characterize the reproducibility of a liquid chromatography method used to isolate and quantitatively characterize modified nucleosides in tRNA and rRNA when nucleoside detection is performed using ultraviolet and mass spectrometric detection (UV and MS, respectively). Despite the analytical challenges of sample isolation and dynamic range, quantitative profiling of modified nucleosides obtained from bacterial tRNAs and rRNAs is feasible at relative standard deviations of 5% RSD or less. PMID:23500350

  11. Supramolecular polymerization of a prebiotic nucleoside provides insights into the creation of sequence-controlled polymers.

    PubMed

    Wang, Jun; Bonnesen, Peter V; Rangel, E; Vallejo, E; Sanchez-Castillo, Ariadna; James Cleaves Ii, H; Baddorf, Arthur P; Sumpter, Bobby G; Pan, Minghu; Maksymovych, Petro; Fuentes-Cabrera, Miguel

    2016-01-01

    Self-assembly of a nucleoside on Au(111) was studied to ascertain whether polymerization on well-defined substrates constitutes a promising approach for making sequence-controlled polymers. Scanning tunneling microscopy and density functional theory were used to investigate the self-assembly on Au(111) of (RS)-N(9)-(2,3-dihydroxypropyl)adenine (DHPA), a plausibly prebiotic nucleoside analog of adenosine. It is found that DHPA molecules self-assemble into a hydrogen-bonded polymer that grows almost exclusively along the herringbone reconstruction pattern, has a two component sequence that is repeated over hundreds of nanometers, and is erasable with electron-induced excitation. Although the sequence is simple, more complicated ones are envisioned if two or more nucleoside types are combined. Because polymerization occurs on a substrate in a dry environment, the success of each combination can be gauged with high-resolution imaging and accurate modeling techniques. These characteristics make nucleoside self-assembly on a substrate an attractive approach for designing sequence-controlled polymers. Further, by choosing plausibly prebiotic nucleosides, insights may be provided into how nature created the first sequence-controlled polymers capable of storing information. Such insights, in turn, can inspire new ways of synthesizing sequence-controlled polymers. PMID:26725380

  12. Apoplastic Nucleoside Accumulation in Arabidopsis Leads to Reduced Photosynthetic Performance and Increased Susceptibility Against Botrytis cinerea

    PubMed Central

    Daumann, Manuel; Fischer, Marietta; Niopek-Witz, Sandra; Girke, Christopher; Möhlmann, Torsten

    2015-01-01

    Interactions between plant and pathogen often occur in the extracellular space and especially nucleotides like ATP and NAD have been identified as key players in this scenario. Arabidopsis mutants accumulating nucleosides in the extracellular space were generated and studied with respect to susceptibility against Botrytis cinerea infection and general plant fitness determined as photosynthetic performance. The mutants used are deficient in the main nucleoside uptake system ENT3 and the extracellular nucleoside hydrolase NSH3. When grown on soil but not in hydroponic culture, these plants markedly accumulate adenosine and uridine in leaves. This nucleoside accumulation was accompanied by reduced photosystem II efficiency and altered expression of photosynthesis related genes. Moreover, a higher susceptibility toward Botrytis cinerea infection and a reduced induction of pathogen related genes PR1 and WRKY33 was observed. All these effects did not occur in hydroponically grown plants substantiating a contribution of extracellular nucleosides to these effects. Whether reduced general plant fitness, altered pathogen response capability or more direct interactions with the pathogen are responsible for these observations is discussed. PMID:26779190

  13. Laboratory study of cometary analogues

    NASA Astrophysics Data System (ADS)

    Colangeli, L.; Brucato, J.; Mennella, V.; Palumbo, P.

    In situ exploration (e.g., GIOTTO mission) and astronomical observations (e.g., ISO) of comets have provided fundamental information about the structure, chemistry and physical properties of materials present in such primordial bodies of the Solar System. Moreover, it is known that cosmic materials evolve, depending on the efficiency of active processes (e.g., thermal annealing, UV irradiation, ion bombardment, gassolid interactions) in different space environments. Thus, the properties of cometary constituents must be considered in a wider perspective, including cosmic dust formation around cold stars and evolution in the interstellar medium until the formation of proto-planetary nebulae. In this scenario, laboratory experiments provide important hints to clarify the status of cometary compounds. The laboratory work is aimed at both reproducing material properties and at simulating their evolution based on the most effective mechanisms active in space. Several techniques are used to synthesise "analogues" of cometary compounds with controlled chemical and physical characteristics. The study of optical properties, complemented by other analytical techniques, is applied to investigate the products of synthesis in the experiments. The monitoring of the effects produced by processing methods, similar to those active in space, provides information both on the reactivity of materials and on the efficiency of treatments. Such an approach is able to provide quantitative information on chemical and structural modifications produced on organic and refractory materials. The comparison of laboratory results with data coming from space observations and in situ measurements provides a powerful tool to understand the real nature of comets and to place constraints on formation and evolution pathways. The laboratory experiments on analogues gain even more relevance as a sort of training in the future perspective of analysing cometary samples returned to Earth by space missions (e

  14. [GnRH analogues containing SV-40 virus T-antigen nuclear localization sequence].

    PubMed

    Burov, S V; Iablokova, T V; Dorosh, M Iu; Kriviziuk, E V; Efremov, A M; Orlov, S V

    2010-01-01

    To improve the efficiency of anticancer drugs due to their delivery to intracellular targets a set of GnRH analogues containing nuclear localization signal (NLS) of SV-40 virus large T-antigen have been synthesized. NLS was attached to the parent molecule via ε-amino group of D-Lysine in position 1 or 6 of peptide sequence using orthogonal protection strategy. The biological activity studies revealed that incorporation of NLS moiety significantly increases cytotoxic activity of palmitoyl-containing GnRH analogues in vitro. The influence of tested peptides on tumor cells does not accompanied by the destruction of cell membrane, as confirmed in experiments with normal fibroblasts, used as a control. PMID:21063449

  15. Novel capsaicin analogues as potential anticancer agents: synthesis, biological evaluation, and in silico approach.

    PubMed

    Damião, Mariana C F C B; Pasqualoto, Kerly F M; Ferreira, Adilson K; Teixeira, Sarah F; Azevedo, Ricardo A; Barbuto, José A M; Palace-Berl, Fanny; Franchi-Junior, Gilberto C; Nowill, Alexandre E; Tavares, Maurício T; Parise-Filho, Roberto

    2014-12-01

    A novel class of benzo[d][1,3]dioxol-5-ylmethyl alkyl/aryl amide and ester analogues of capsaicin were designed, synthesized, and evaluated for their cytotoxic activity against human and murine cancer cell lines (B16F10, SK-MEL-28, NCI-H1299, NCI-H460, SK-BR-3, and MDA-MB-231) and human lung fibroblasts (MRC-5). Three compounds (5f, 6c, and 6e) selectively inhibited the growth of aggressive cancer cells in the micromolar (µM) range. Furthermore, an exploratory data analysis pointed at the topological and electronic molecular properties as responsible for the discrimination process regarding the set of investigated compounds. The findings suggest that the applied designing strategy, besides providing more potent analogues, indicates the aryl amides and esters as well as the alkyl esters as interesting scaffolds to design and develop novel anticancer agents. PMID:25283529

  16. Probing the TRAP-RNA interaction with nucleoside analogs.

    PubMed

    Elliott, M B; Gottlieb, P A; Gollnick, P

    1999-10-01

    The trp RNA-binding Attenuation Protein (TRAP) from Bacillus subtilis binds a series of GAG and UAG repeats separated by 2-3 nonconserved spacer nucleotides in trp leader mRNA. To identify chemical groups on the RNA required for stability of the TRAP-RNA complex, we introduced several different nucleoside analogs into each pentamer of the RNA sequence 5'-(UAGCC)-3' repeated 11 times and measured their effect on the TRAP-RNA interaction. Deoxyribonucleoside substitutions revealed that a 2'-hydroxyl group (2'-OH) is required only on the guanosine occupying the third residue of the RNA triplets for high-affinity binding to TRAP. The remaining hydroxyl groups are dispensable. Base analog substitutions identified all of the exocyclic functional groups and N1 nitrogens of adenine and guanine in the second and third nucleotides, respectively, of the triplets as being involved in binding TRAP. In contrast, none of the substitutions made in the first residue caused any detectable changes in affinity, indicating that elements of these bases are not necessary for complex formation and stability. Studies using abasic nucleotides in the first residue of the triplets and in the two spacer residues confirmed that the majority of the specificity and stability of the TRAP-RNA complex is provided by the AG dinucleotide of the triplet repeats. In addition to direct effects on binding, we demonstrate that the N7-nitrogen of adenosine and guanosine in UAG triplet and the 2'-OHs of (UAGCC)11 RNA are involved in the formation of an as yet undetermined structure that interferes with TRAP binding. PMID:10573119

  17. The concentrative nucleoside transporter family (SLC28): new roles beyond salvage?

    PubMed

    Aymerich, I; Duflot, S; Fernández-Veledo, S; Guillén-Gómez, E; Huber-Ruano, I; Casado, F J; Pastor-Anglada, M

    2005-02-01

    The concentrative nucleoside transporter (CNT) family (SLC28) has three members: SLC28A1 (CNT1), SLC28A2 (CNT2) and SLC28A3 (CNT3). The CNT1 and CNT2 transporters are co-expressed in liver parenchymal cells and macrophages, two suitable models in which to study cell cycle progression. Despite initial observations suggesting that these transporter proteins might contribute to nucleoside salvage during proliferation, their subcellular localization and regulatory properties suggest alternative roles in cell physiology. In particular, CNT2 is a suitable candidate for modulation of purinergic responses, since it is under the control of the adenosine 1 receptor. Increasing evidence also suggests a role for CNT2 in energy metabolism, since its activation relies on the opening of ATP-sensitive K(+) channels. Animal and cell models genetically modified to alter nucleoside transporter expression levels may help to elucidate the particular roles of CNT proteins in cell physiology. PMID:15667311

  18. Structural and Enzymatic Characterization of a Nucleoside Diphosphate Sugar Hydrolase from Bdellovibrio bacteriovorus

    PubMed Central

    Duong-ly, Krisna C.; Schoeffield, Andrew J.; Pizarro-Dupuy, Mario A.; Zarr, Melissa; Pineiro, Silvia A.; Amzel, L. Mario; Gabelli, Sandra B.

    2015-01-01

    Given the broad range of substrates hydrolyzed by Nudix (nucleoside diphosphate linked to X) enzymes, identification of sequence and structural elements that correctly predict a Nudix substrate or characterize a family is key to correctly annotate the myriad of Nudix enzymes. Here, we present the structure determination and characterization of Bd3179 –- a Nudix hydrolase from Bdellovibrio bacteriovorus–that we show localized in the periplasmic space of this obligate Gram-negative predator. We demonstrate that the enzyme is a nucleoside diphosphate sugar hydrolase (NDPSase) and has a high degree of sequence and structural similarity to a canonical ADP-ribose hydrolase and to a nucleoside diphosphate sugar hydrolase (1.4 and 1.3 Å Cα RMSD respectively). Examination of the structural elements conserved in both types of enzymes confirms that an aspartate-X-lysine motif on the C-terminal helix of the α-β-α NDPSase fold differentiates NDPSases from ADPRases. PMID:26524597

  19. Development of a Diastereoselective Phosphorylation of a Complex Nucleoside via Dynamic Kinetic Resolution.

    PubMed

    Tran, Kristy; Beutner, Gregory L; Schmidt, Michael; Janey, Jacob; Chen, Ke; Rosso, Victor; Eastgate, Martin D

    2015-05-15

    The development of a diastereoselective nucleoside phosphorylation is described, which produces a single isomer of a complex nucleoside monophosphate pro-drug. A stable phosphoramidic acid derivative is coupled to the nucleoside, in a process mediated by HATU and quinine, to deliver the coupled product in high chemical yield and good diastereoselectivity. This unusual process was shown to proceed through a dynamic kinetic resolution of a 1:1 mixture of activated phosphonate ester diastereoisomers. The optimized conditions afforded the product with a combined [S,S(P)] and [S,R(P)] in-process yield of 89% and a ∼7:1 [S,S(P):S,R(P)] diastereomeric ratio. Isolation of the major isomer was facilitated by single crystallization from anisole, where the product was obtained in 57% isolated yield, excellent purity (>95%), and a high diastereomeric ratio (>50:1). PMID:25840459

  20. Structure of purine nucleoside phosphorylase (DeoD) from Bacillus anthracis

    SciTech Connect

    Grenha, Rosa; Levdikov, Vladimir M.; Fogg, Mark J.; Blagova, Elena V.; Brannigan, James A. Wilkinson, Anthony J.; Wilson, Keith S.

    2005-05-01

    The crystal structure of purine nucleoside phosphorylase (DeoD) from B. anthracis was solved by X-ray crystallography using molecular replacement and refined at a resolution of 2.24 Å. Protein structures from the causative agent of anthrax (Bacillus anthracis) are being determined as part of a structural genomics programme. Amongst initial candidates for crystallographic analysis are enzymes involved in nucleotide biosynthesis, since these are recognized as potential targets in antibacterial therapy. Purine nucleoside phosphorylase is a key enzyme in the purine-salvage pathway. The crystal structure of purine nucleoside phosphorylase (DeoD) from B. anthracis has been solved by molecular replacement at 2.24 Å resolution and refined to an R factor of 18.4%. This is the first report of a DeoD structure from a Gram-positive bacterium.

  1. A photoaffinity analogue of discodermolide specifically labels a peptide in beta-tubulin.

    PubMed

    Xia, Shujun; Kenesky, Craig S; Rucker, Paul V; Smith, Amos B; Orr, George A; Horwitz, Susan Band

    2006-10-01

    Discodermolide is a potentially important antitumor agent that stabilizes microtubules and blocks cells at the G2/M phase of the cell cycle in a manner similar to that of Taxol. Discodermolide also has unique properties that distinguish it from Taxol. In the present study, photoaffinity-labeled discodermolide analogues are used to investigate their binding site in tubulin. Three photoaffinity-labeled discodermolide analogues were synthesized, all of which promoted microtubule polymerization in the absence of GTP. The analogue, C19-[4-(4-(3)H-benzoyl-phenyl)-carbamate]-discodermolide (C19-[3H]BPC-discodermolide), was selected for photolabeling studies because it had the highest extent of photoincorporation, approximately 1%, of the three radiolabeled discodermolide analogues explored. Although compared to discodermolide, C19-BPC-discodermolide revealed no hypernucleation effect in the in vitro microtubule polymerization assay, it was more cytotoxic than discodermolide, and, like discodermolide, demonstrated synergism with Taxol. These results suggest that the hypernucleation effect of discodermolide is not involved in its cytotoxic activity. Similar to discodermolide, C19-BPC-discodermolide can effectively displace [3H]Taxol from microtubules, but Taxol cannot effectively displace C19-[3H]BPC-discodermolide binding. Discodermolide can effectively displace C19-[3H]BPC-discodermolide binding. Formic acid hydrolysis, immunoprecipitation experiments, and subtilisin digestion indicate that C19-BPC-discodermolide labels amino acid residues 305-433 in beta-tubulin. Further digestion with Asp-N and Arg-C enzymes suggested that C19-BPC-discodermolide binds to amino acid residues, 355-359, in beta-tubulin, which is in close proximity to the Taxol binding site. Molecular modeling guided by the above evidence led to a putative binding model for C19-BPC-discodermolide in tubulin. PMID:17002277

  2. Synthesis and biochemical evaluation of benzoylbenzophenone thiosemicarbazone analogues as potent and selective inhibitors of cathepsin L.

    PubMed

    Parker, Erica N; Song, Jiangli; Kishore Kumar, G D; Odutola, Samuel O; Chavarria, Gustavo E; Charlton-Sevcik, Amanda K; Strecker, Tracy E; Barnes, Ashleigh L; Sudhan, Dhivya R; Wittenborn, Thomas R; Siemann, Dietmar W; Horsman, Michael R; Chaplin, David J; Trawick, Mary Lynn; Pinney, Kevin G

    2015-11-01

    Upregulation of cathepsin L in a variety of tumors and its ability to promote cancer cell invasion and migration through degradation of the extracellular matrix suggest that cathepsin L is a promising biological target for the development of anti-metastatic agents. Based on encouraging results from studies on benzophenone thiosemicarbazone cathepsin inhibitors, a series of fourteen benzoylbenzophenone thiosemicarbazone analogues were designed, synthesized, and evaluated for their inhibitory activity against cathepsins L and B. Thiosemicarbazone inhibitors 3-benzoylbenzophenone thiosemicarbazone 1, 1,3-bis(4-fluorobenzoyl)benzene thiosemicarbazone 8, and 1,3-bis(2-fluorobenzoyl)-5-bromobenzene thiosemicarbazone 32 displayed the greatest potency against cathepsin L with low IC50 values of 9.9 nM, 14.4 nM, and 8.1 nM, respectively. The benzoylbenzophenone thiosemicarbazone analogues evaluated were selective in their inhibition of cathepsin L compared to cathepsin B. Thiosemicarbazone analogue 32 inhibited invasion through Matrigel of MDA-MB-231 breast cancer cells by 70% at 10 μM. Thiosemicarbazone analogue 8 significantly inhibited the invasive potential of PC-3ML prostate cancer cells by 92% at 5 μM. The most active cathepsin L inhibitors from this benzoylbenzophenone thiosemicarbazone series (1, 8, and 32) displayed low cytotoxicity toward normal primary cells [in this case human umbilical vein endothelial cells (HUVECs)]. In an initial in vivo study, 3-benzoylbenzophenone thiosemicarbazone (1) was well-tolerated in a CDF1 mouse model bearing an implanted C3H mammary carcinoma, and showed efficacy in tumor growth delay. Low cytotoxicity, inhibition of cell invasion, and in vivo tolerability are desirable characteristics for anti-metastatic agents functioning through an inhibition of cathepsin L. Active members of this structurally diverse group of benzoylbenzophenone thiosemicarbazone cathepsin L inhibitors show promise as potential anti-metastatic, pre

  3. Prodrugs of reverse fosmidomycin analogues.

    PubMed

    Brücher, Karin; Gräwert, Tobias; Konzuch, Sarah; Held, Jana; Lienau, Claudia; Behrendt, Christoph; Illarionov, Boris; Maes, Louis; Bacher, Adelbert; Wittlin, Sergio; Mordmüller, Benjamin; Fischer, Markus; Kurz, Thomas

    2015-02-26

    Fosmidomycin inhibits IspC (Dxr, 1-deoxy-d-xylulose 5-phosphate reductoisomerase), a key enzyme in nonmevalonate isoprenoid biosynthesis that is essential in Plasmodium falciparum. The drug has been used successfully to treat malaria patients in clinical studies, thus validating IspC as an antimalarial target. However, improvement of the drug's pharmacodynamics and pharmacokinetics is desirable. Here, we show that the conversion of the phosphonate moiety into acyloxymethyl and alkoxycarbonyloxymethyl groups can increase the in vitro activity against asexual blood stages of P. falciparum by more than 1 order of magnitude. We also synthesized double prodrugs by additional esterification of the hydroxamate moiety. Prodrugs with modified hydroxamate moieties are subject to bioactivation in vitro. All prodrugs demonstrated improved antiplasmodial in vitro activity. Selected prodrugs and parent compounds were also tested for their cytotoxicity toward HeLa cells and in vivo in a Plasmodium berghei malaria model as well as in the SCID mouse P. falciparum model. PMID:25633870

  4. Functional and genetic diversity in the concentrative nucleoside transporter, CNT1, in human populations.

    PubMed

    Gray, Jennifer H; Mangravite, Lara M; Owen, Ryan P; Urban, Thomas J; Chan, Wendy; Carlson, Elaine J; Huang, Conrad C; Kawamoto, Michiko; Johns, Susan J; Stryke, Douglas; Ferrin, Thomas E; Giacomini, Kathleen M

    2004-03-01

    The concentrative nucleoside transporter, CNT1 (SLC28A1), mediates the cellular uptake of naturally occurring pyrimidine nucleosides and many structurally diverse anticancer and antiviral nucleoside analogs. As a first step toward understanding whether genetic variation in CNT1 contributes to variation in the uptake and disposition of clinically used nucleoside analogs, we determined the haplotype structure and functionally analyzed all coding region variants of CNT1 identified in ethnically diverse populations (100 African Americans, 100 European Americans, 30 Asians, 10 Mexican Americans, and 7 Pacific Islanders) (Leabman et al., 2003). A total of 58 coding region haplotypes were identified using PHASE analysis, 44 of which contained at least one amino acid variant. More than half of the coding region haplotypes were population-specific. Using site-directed mutagenesis, 15 protein-altering CNT1 variants, including one amino acid insertion and one base pair (bp) deletion, were constructed and expressed in Xenopus laevis oocytes. All variant transporters took up [3H]thymidine with the exception of CNT1-Ser546Pro, a rare variant, and CNT1-1153del, a single bp deletion found at a frequency of 3% in the African American population. The bp deletion results in a frame-shift followed by a stop-codon. The anticancer nucleoside analog gemcitabine had a reduced affinity for CNT1-Val189Ile (a common CNT1 variant found at a frequency of 26%) compared with reference CNT1 (IC50=13.8 +/- 0.60 microM for CNT1-reference and 23.3 +/- 1.5 microM for CNT1-Val189Ile, p<0.05). These data suggest that common genetic variants of CNT1 may contribute to variation in systemic and intracellular levels of anti-cancer nucleoside analogs. PMID:14978229

  5. Nucleoside transporter proteins as biomarkers of drug responsiveness and drug targets

    PubMed Central

    Pastor-Anglada, Marçal; Pérez-Torras, Sandra

    2015-01-01

    Nucleoside and nucleobase analogs are currently used in the treatment of solid tumors, lymphoproliferative diseases, viral infections such as hepatitis and AIDS, and some inflammatory diseases such as Crohn. Two gene families are implicated in the uptake of nucleosides and nucleoside analogs into cells, SCL28 and SLC29. The former encodes hCNT1, hCNT2, and hCNT3 proteins. They translocate nucleosides in a Na+ coupled manner with high affinity and some substrate selectivity, being hCNT1 and hCNT2 pyrimidine- and purine-preferring, respectively, and hCNT3 a broad selectivity transporter. SLC29 genes encode four members, being hENT1 and hENT2 the only two which are unequivocally implicated in the translocation of nucleosides and nucleobases (the latter mostly via hENT2) at the cell plasma membrane. Some nucleoside-derived drugs can also interact with and be translocated by members of the SLC22 gene family, particularly hOCT and hOAT proteins. Inter-individual differences in transporter function and perhaps, more importantly, altered expression associated with the disease itself might modulate the transporter profile of target cells, thereby determining drug bioavailability and action. Drug transporter pharmacology has been periodically reviewed. Thus, with this contribution we aim at providing a state-of-the-art overview of the clinical evidence generated so far supporting the concept that these membrane proteins can indeed be biomarkers suitable for diagnosis and/or prognosis. Last but not least, some of these transporter proteins can also be envisaged as drug targets, as long as they can show “transceptor” functions, in some cases related to their role as modulators of extracellular adenosine levels, thereby providing a functional link between P1 receptors and transporters. PMID:25713533

  6. Isolation and functional characterization of the PfNT1 nucleoside transporter gene from Plasmodium falciparum.

    PubMed

    Carter, N S; Ben Mamoun, C; Liu, W; Silva, E O; Landfear, S M; Goldberg, D E; Ullman, B

    2000-04-01

    Plasmodium falciparum, the causative agent of the most lethal form of human malaria, is incapable of de novo purine synthesis, and thus, purine acquisition from the host is an indispensable nutritional requirement. This purine salvage process is initiated by the transport of preformed purines into the parasite. We have identified a gene encoding a nucleoside transporter from P. falciparum, PfNT1, and analyzed its function and expression during intraerythrocytic parasite development. PfNT1 predicts a polypeptide of 422 amino acids with 11 transmembrane domains that is homologous to other members of the equilibrative nucleoside transporter family. Southern analysis and BLAST searching of The Institute for Genomic Research (TIGR) malaria data base indicate that PfNT1 is a single copy gene located on chromosome 14. Northern analysis of RNA from intraerythrocytic stages of the parasite demonstrates that PfNT1 is expressed throughout the asexual life cycle but is significantly elevated during the early trophozoite stage. Functional expression of PfNT1 in Xenopus laevis oocytes significantly increases their ability to take up naturally occurring D-adenosine (K(m) = 13.2 microM) and D-inosine (K(m) = 253 microM). Significantly, PfNT1, unlike the mammalian nucleoside transporters, also has the capacity to transport the stereoisomer L-adenosine (K(m) > 500 microM). Inhibition studies with a battery of purine and pyrimidine nucleosides and bases as well as their analogs indicate that PfNT1 exhibits a broad substrate specificity for purine and pyrimidine nucleosides. These data provide compelling evidence that PfNT1 encodes a functional purine/pyrimidine nucleoside transporter whose expression is strongly developmentally regulated in the asexual stages of the P. falciparum life cycle. Moreover, the unusual ability to transport L-adenosine and the vital contribution of purine transport to parasite survival makes PfNT1 an attractive target for therapeutic evaluation. PMID

  7. Evidence for incorporation of intact dietary pyrimidine (but not purine) nucleosides into hepatic RNA.

    PubMed Central

    Berthold, H K; Crain, P F; Gouni, I; Reeds, P J; Klein, P D

    1995-01-01

    The absorption and metabolism of dietary nucleic acids have received less attention than those of other organic nutrients, largely because of methodological difficulties. We supplemented the rations of poultry and mice with the edible alga Spirulina platensis, which had been uniformly labeled with 13C by hydroponic culture in 13CO2. The rations were ingested by a hen for 4 wk and by four mice for 6 days; two mice were fed a normal diet and two were fed a nucleic acid-deficient diet. The animals were killed and nucleosides were isolated from hepatic RNA. The isotopic enrichment of all mass isotopomers of the nucleosides was analyzed by selected ion monitoring of the negative chemical ionization mass spectrum and the labeling pattern was deconvoluted by reference to the enrichment pattern of the tracer material. We found a distinct difference in the 13C enrichment pattern between pyrimidine and purine nucleosides; the isotopic enrichment of uniformly labeled [M + 9] isotopomers of pyrimidines exceeded that of purines [M + 10] by > 2 orders of magnitude in the avian nucleic acids and by 7- and 14-fold in the murine nucleic acids. The purines were more enriched in lower mass isotopomers, those less than [M + 3], than the pyrimidines. Our results suggest that large quantities of dietary pyrimidine nucleosides and almost no dietary purine nucleosides are incorporated into hepatic nucleic acids without hydrolytic removal of the ribose moiety. In addition, our results support a potential nutritional role for nucleosides and suggest that pyrimidines are conditionally essential organic nutrients. PMID:7479738

  8. Plant volatile analogues strengthen attractiveness to insect.

    PubMed

    Sun, Yufeng; Yu, Hao; Zhou, Jing-Jiang; Pickett, John A; Wu, Kongming

    2014-01-01

    Green leaf bug Apolygus lucorum (Meyer-Dür) is one of the major pests in agriculture. Management of A. lucorum was largely achieved by using pesticides. However, the increasing population of A. lucorum since growing Bt cotton widely and the increased awareness of ecoenvironment and agricultural product safety makes their population-control very challenging. Therefore this study was conducted to explore a novel ecological approach, synthetic plant volatile analogues, to manage the pest. Here, plant volatile analogues were first designed and synthesized by combining the bioactive components of β-ionone and benzaldehyde. The stabilities of β-ionone, benzaldehyde and analogue 3 g were tested. The electroantennogram (EAG) responses of A. lucorum adult antennae to the analogues were recorded. And the behavior assay and filed experiment were also conducted. In this study, thirteen analogues were acquired. The analogue 3 g was demonstrated to be more stable than β-ionone and benzaldehyde in the environment. Many of the analogues elicited EAG responses, and the EAG response values to 3 g remained unchanged during seven-day period. 3 g was also demonstrated to be attractive to A. lucorum adults in the laboratory behavior experiment and in the field. Its attractiveness persisted longer than β-ionone and benzaldehyde. This indicated that 3 g can strengthen attractiveness to insect and has potential as an attractant. Our results suggest that synthetic plant volatile analogues can strengthen attractiveness to insect. This is the first published study about synthetic plant volatile analogues that have the potential to be used in pest control. Our results will support a new ecological approach to pest control and it will be helpful to ecoenvironment and agricultural product safety. PMID:24911460

  9. Plant Volatile Analogues Strengthen Attractiveness to Insect

    PubMed Central

    Sun, Yufeng; Yu, Hao; Zhou, Jing-Jiang; Pickett, John A.; Wu, Kongming

    2014-01-01

    Green leaf bug Apolygus lucorum (Meyer-Dür) is one of the major pests in agriculture. Management of A. lucorum was largely achieved by using pesticides. However, the increasing population of A. lucorum since growing Bt cotton widely and the increased awareness of ecoenvironment and agricultural product safety makes their population-control very challenging. Therefore this study was conducted to explore a novel ecological approach, synthetic plant volatile analogues, to manage the pest. Here, plant volatile analogues were first designed and synthesized by combining the bioactive components of β-ionone and benzaldehyde. The stabilities of β-ionone, benzaldehyde and analogue 3 g were tested. The electroantennogram (EAG) responses of A. lucorum adult antennae to the analogues were recorded. And the behavior assay and filed experiment were also conducted. In this study, thirteen analogues were acquired. The analogue 3 g was demonstrated to be more stable than β-ionone and benzaldehyde in the environment. Many of the analogues elicited EAG responses, and the EAG response values to 3 g remained unchanged during seven-day period. 3 g was also demonstrated to be attractive to A. lucorum adults in the laboratory behavior experiment and in the field. Its attractiveness persisted longer than β-ionone and benzaldehyde. This indicated that 3 g can strengthen attractiveness to insect and has potential as an attractant. Our results suggest that synthetic plant volatile analogues can strengthen attractiveness to insect. This is the first published study about synthetic plant volatile analogues that have the potential to be used in pest control. Our results will support a new ecological approach to pest control and it will be helpful to ecoenvironment and agricultural product safety. PMID:24911460

  10. Biological and chemical study of fused tri- and tetracyclic indazoles and analogues with important antiparasitic activity

    NASA Astrophysics Data System (ADS)

    Díaz-Urrutia, Christian A.; Olea-Azar, Claudio A.; Zapata, Gerald A.; Lapier, Michel; Mura, Francisco; Aguilera-Venegas, Benjamín; Arán, Vicente J.; López-Múñoz, Rodrigo A.; Maya, Juan D.

    A series of fused tri- and tetracyclic indazoles and analogues compounds (NID) with potential antiparasitic effects were studied using voltamperometric and spectroscopic techniques. Nitroanion radicals generated by cyclic voltammetry were characterized by electron spin resonance spectroscopy (ESR) and their spectral lines were explained and analyzed using simulated spectra. In addition, we examined the interaction between radical species generated from nitroindazole derivatives and glutathione (GSH). Biological assays such as activity against Trypanosoma cruzi and cytotoxicity against macrophages were carried out. Finally, spin trapping and molecular modeling studies were also done in order to elucidate the potentials action mechanisms involved in the trypanocidal activity.

  11. Distribution of the modified nucleoside Q and its derivatives in animal and plant transfer RNA's.

    PubMed Central

    Kasai, H; Kuchino, Y; Nihei, K; Nishimura, S

    1975-01-01

    The modified nucleoside, 7-(4,5-cis-dihydroxy-1-cyclopenten-3-yl-aminomethyl)-7-deazaguanosine, designated as Q, and its derivative, Q*, were found in tRNA's from various organisms, including several mammalian tissues, other animals such as starfish, lingula and hagfish, and wheat germ. Q isolated from rat liver tRNA was found to be identical with E. coli Q by mass spectrometry and thin-layer chromatography. Thus the rare modified nucleoside Q originally isolated from E. coli tRNA, is widely distributed in various organisms. Analysis of the mass spectrum of Q* suggested that it has a different side chain from Q. PMID:1187350

  12. Structure of purine nucleoside phosphorylase (DeoD) from Bacillus anthracis

    PubMed Central

    Grenha, Rosa; Levdikov, Vladimir M.; Fogg, Mark J.; Blagova, Elena V.; Brannigan, James A.; Wilkinson, Anthony J.; Wilson, Keith S.

    2005-01-01

    Protein structures from the causative agent of anthrax (Bacillus anthracis) are being determined as part of a structural genomics programme. Amongst initial candidates for crystallographic analysis are enzymes involved in nucleotide biosynthesis, since these are recognized as potential targets in antibacterial therapy. Purine nucleoside phosphorylase is a key enzyme in the purine-salvage pathway. The crystal structure of purine nucleoside phosphorylase (DeoD) from B. anthracis has been solved by molecular replacement at 2.24 Å resolution and refined to an R factor of 18.4%. This is the first report of a DeoD structure from a Gram-positive bacterium. PMID:16511068

  13. Synthesis of optically pure dioxolane nucleosides and their anti-HIV activity

    SciTech Connect

    Siddigui, M.A.; Evans, C.; Jin, H.L.; Tse, A.; Brown, W.; Nguyen-Ba, N.; Mansour, T.S.; Cameron, J.M.

    1993-12-31

    The clinical candidate 3TC, 1, possessing non-natural absolute stereochemistry is a potent and non-toxic inhibitor of a key enzyme, reverse transcriptase, involved in the replicative cycle of the HIV. Selective inhibition of both HIV and HBV is seen. In view of the authors` interest in finding correlation between stereochemistry and antiviral activity, several enantiomerically pure dioxolane nucleosides, 2, were synthesized and assayed. The discussion will focus on (a) the synthesis of optically pure dioxolane sugars from L-ascorbic acid, (b) enzymatic resolution of purine dioxolane nucleosides, (c) anti HIV-1 activity in MT-4 cells.

  14. Synthesis and in vitro growth inhibitory activity of novel silyl- and trityl-modified nucleosides.

    PubMed

    Panayides, Jenny-Lee; Mathieu, Véronique; Banuls, Laetitia Moreno Y; Apostolellis, Helen; Dahan-Farkas, Nurit; Davids, Hajierah; Harmse, Leonie; Rey, M E Christine; Green, Ivan R; Pelly, Stephen C; Kiss, Robert; Kornienko, Alexander; van Otterlo, Willem A L

    2016-06-15

    Seventeen silyl- and trityl-modified (5'-O- and 3',5'-di-O-) nucleosides were synthesized with the aim of investigating the in vitro antiproliferative activities of these nucleoside derivatives. A subset of the compounds was evaluated at a fixed concentration of 100μM against a small panel of tumor cell lines (HL-60, K-562, Jurkat, Caco-2 and HT-29). The entire set was also tested at varying concentrations against two human glioma lines (U373 and Hs683) to obtain GI50 values, with the best results being values of ∼25μM. PMID:27157005

  15. Identification of flavopiridol analogues that selectively inhibit positive transcription elongation factor (P-TEFb) and block HIV-1 replication.

    PubMed

    Ali, Akbar; Ghosh, Animesh; Nathans, Robin S; Sharova, Natalia; O'Brien, Siobhan; Cao, Hong; Stevenson, Mario; Rana, Tariq M

    2009-08-17

    The positive transcription elongation factor (P-TEFb; CDK9/cyclin T1) regulates RNA polymerase II-dependent transcription of cellular and integrated viral genes. It is an essential cofactor for HIV-1 Tat transactivation, and selective inhibition of P-TEFb blocks HIV-1 replication without affecting cellular transcription; this indicates that P-TEFb could be a potential target for developing anti-HIV-1 therapeutics. Flavopiridol, a small molecule CDK inhibitor, blocks HIV-1 Tat transactivation and viral replication by inhibiting P-TEFb kinase activity, but it is highly cytotoxic. In the search for selective and less cytotoxic P-TEFb inhibitors, we prepared a series of flavopiridol analogues and evaluated their kinase inhibitory activity against P-TEFb and CDK2/cyclin A, and tested their cellular antiviral potency and cytotoxicity. We identified several analogues that selectively inhibit P-TEFb kinase activity in vitro and show antiviral potency comparable to that of flavopiridol, but with significantly reduced cytotoxicity. These compounds are valuable molecular probes for understanding P-TEFb-regulated cellular and HIV-1 gene transcription and provide potential anti-HIV-1 therapeutics. PMID:19603446

  16. Space analogue studies in Antarctica

    NASA Astrophysics Data System (ADS)

    Lugg, D.; Shepanek, M.

    1999-09-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mltogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  17. Condensed matter analogues of cosmology

    NASA Astrophysics Data System (ADS)

    Kibble, Tom; Srivastava, Ajit

    2013-10-01

    It is always exciting when developments in one branch of physics turn out to have relevance in a quite different branch. It would be hard to find two branches farther apart in terms of energy scales than early-universe cosmology and low-temperature condensed matter physics. Nevertheless ideas about the formation of topological defects during rapid phase transitions that originated in the context of the very early universe have proved remarkably fruitful when applied to a variety of condensed matter systems. The mathematical frameworks for describing these systems can be very similar. This interconnection has led to a deeper understanding of the phenomena in condensed matter systems utilizing ideas from cosmology. At the same time, one can view these condensed matter analogues as providing, at least in a limited sense, experimental access to the phenomena of the early universe for which no direct probe is possible. As this special issue well illustrates, this remains a dynamic and exciting field. The basic idea is that when a system goes through a rapid symmetry-breaking phase transition from a symmetric phase into one with spontaneously broken symmetry, the order parameter may make different choices in different regions, creating domains that when they meet can trap defects. The scale of those domains, and hence the density of defects, is constrained by the rate at which the system goes through the transition and the speed with which order parameter information propagates. This is what has come to be known as the Kibble-Zurek mechanism. The resultant scaling laws have now been tested in a considerable variety of different systems. The earliest experiments illustrating the analogy between cosmology and condensed matter were in liquid crystals, in particular on the isotropic-to-nematic transition, primarily because it is very easy to induce the phase transition (typically at room temperature) and to image precisely what is going on. This field remains one of the

  18. Antimicrobial activity of resveratrol analogues.

    PubMed

    Chalal, Malik; Klinguer, Agnès; Echairi, Abdelwahad; Meunier, Philippe; Vervandier-Fasseur, Dominique; Adrian, Marielle

    2014-01-01

    Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of activity ranging from low to high. Six of them, including the most active ones, were subsequently tested on the development of Botrytis cinerea (fungus responsible for grey mold). The results obtained allowed us to identify the most active stilbenes against both grapevine pathogens, to compare the antimicrobial activity of the evaluated series of stilbenes, and to discuss the relationship between their chemical structure (number and position of methoxy and hydroxy groups) and antimicrobial activity. PMID:24918540

  19. Space analogue studies in Antarctica

    NASA Technical Reports Server (NTRS)

    Lugg, D.; Shepanek, M.

    1999-01-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  20. Cytotoxic ent-kaurane diterpenoids from Isodon wikstroemioides.

    PubMed

    Wu, Hai-Yan; Zhan, Rui; Wang, Wei-Guang; Jiang, Hua-Yi; Du, Xue; Li, Xiao-Nian; Li, Yan; Pu, Jian-Xin; Sun, Han-Dong

    2014-04-25

    Phytochemical investigation of EtOAc extracts of the aerial parts of Isodon wikstroemioides afforded 18 new ent-kaurane diterpenoids (wikstroemioidins E-V, 1-18), along with 17 known analogues (19-35). The absolute configurations of 1 and 16 were confirmed by single-crystal X-ray diffraction analysis. The isolates were screened against five human tumor cell lines; compounds 3, 4, 9, 11-13, 23, 25-28, and 33 exhibited significant cytotoxic activity against all five, with IC50 values ranging from 0.4 to 5.1 μM. In addition, 17 of the isolates strongly inhibited nitric oxide production in LPS-activated RAW264.7 macrophages. PMID:24697496

  1. C4-substituted isoquinolines: synthesis and cytotoxic action.

    PubMed

    Tsotinis, A; Zouroudis, S; Moreau, D; Roussakis, C

    2007-01-01

    A facile synthesis of the C4-substituted isoquinolines 5a-c and 6a-c is described. Commercially available 4-bromoisoquinoline is converted to the alpha,beta-unsaturated esters 8 and 10 on treatment with the appropriate acrylate ester under Heck reaction conditions. The saturated amides 5a-c were obtained from the reaction of ester 9 with the requisite primary amine. Similarly the unsaturated analogues 6a-c were prepared by reacting ester 10 with the appropriate amine. The cytotoxicity of the target molecules was evaluated in two tumour cell lines in vitro. Two compounds, 6b and 6c, showed sufficient activity in the human non-small cell lung cancer line NSCLC-N16-L16 to be worthy of further study. PMID:19662134

  2. C4-Substituted Isoquinolines: Synthesis and Cytotoxic Action

    PubMed Central

    Tsotinis, A; Zouroudis, S; Moreau, D; Roussakis, C

    2007-01-01

    A facile synthesis of the C4-substituted isoquinolines 5a-c and 6a-c is described. Commercially available 4-bromoisoquinoline is converted to the α,β-unsaturated esters 8 and 10 on treatment with the appropriate acrylate ester under Heck reaction conditions. The saturated amides 5a-c were obtained from the reaction of ester 9 with the requisite primary amine. Similarly the unsaturated analogues 6a-c were prepared by reacting ester 10 with the appropriate amine. The cytotoxicity of the target molecules was evaluated in two tumour cell lines in vitro. Two compounds, 6b and 6c, showed sufficient activity in the human non-small cell lung cancer line NSCLC-N16-L16 to be worthy of further study. PMID:19662134

  3. Yeast-based high-throughput screen identifies Plasmodium falciparum equilibrative nucleoside transporter 1 inhibitors that kill malaria parasites.

    PubMed

    Frame, I J; Deniskin, Roman; Rinderspacher, Alison; Katz, Francine; Deng, Shi-Xian; Moir, Robyn D; Adjalley, Sophie H; Coburn-Flynn, Olivia; Fidock, David A; Willis, Ian M; Landry, Donald W; Akabas, Myles H

    2015-03-20

    Equilibrative transporters are potential drug targets; however, most functional assays involve radioactive substrate uptake that is unsuitable for high-throughput screens (HTS). We developed a robust yeast-based growth assay that is potentially applicable to many equilibrative transporters. As proof of principle, we applied our approach to Equilibrative Nucleoside Transporter 1 of the malarial parasite Plasmodium falciparum (PfENT1). PfENT1 inhibitors might serve as novel antimalarial drugs since PfENT1-mediated purine import is essential for parasite proliferation. To identify PfENT1 inhibitors, we screened 64 560 compounds and identified 171 by their ability to rescue the growth of PfENT1-expressing fui1Δ yeast in the presence of a cytotoxic PfENT1 substrate, 5-fluorouridine (5-FUrd). In secondary assays, nine of the highest activity compounds inhibited PfENT1-dependent growth of a purine auxotrophic yeast strain with adenosine as the sole purine source (IC50 0.2-2 μM). These nine compounds completely blocked [(3)H]adenosine uptake into PfENT1-expressing yeast and erythrocyte-free trophozoite-stage parasites (IC50 5-50 nM), and inhibited chloroquine-sensitive and -resistant parasite proliferation (IC50 5-50 μM). Wild-type (WT) parasite IC50 values were up to 4-fold lower compared to PfENT1-knockout (pfent1Δ) parasites. pfent1Δ parasite killing showed a delayed-death phenotype not observed with WT. We infer that, in parasites, the compounds inhibit both PfENT1 and a secondary target with similar efficacy. The secondary target identity is unknown, but its existence may reduce the likelihood of parasites developing resistance to PfENT1 inhibitors. Our data support the hypothesis that blocking purine transport through PfENT1 may be a novel and compelling approach for antimalarial drug development. PMID:25602169

  4. 5-(1-Substituted) alkyl pyrimidine nucleosides as antiviral (herpes) agents.

    PubMed

    Kumar, Rakesh

    2004-10-01

    The treatment of viral diseases remains one of the major challenges to modern medicine. During the past two decades there has been increased recognition of the consequences of serious viral illnesses that are not controlled by vaccination. These illnesses include human immunodeficiency virus, human herpes viruses, and viruses that cause hepatitis. There are now eight pathogens recognized in the herpes virus family that cause infections in humans. Infections by the herpes viruses are opportunistic and often life-threatening, leading to significant morbidity and mortality in the increasing number of chronically immune compromised individuals such as AIDS patients, cancer patients and transplant recipients on immunosuppressive therapy. Nearly all individuals with AIDS are infected with one or more of the herpes viruses. Antiviral therapy with guanosine nucleoside analogs acyclovir and ganciclovir has had a major impact on diseases caused by herpes simplex virus type-1 and type-2 (HSV-1, HSV-2), Varicella zoster virus (VZV), and human cytomegalovirus (HCMV) but development of resistant virus strains and the absence of any effective treatment for other members of the herpes family provide a stimulus for increased search of new agents effective against various herpes viruses. Pyrimidine nucleosides have taken up an important role in the therapy of virus infection. Significant progress in the study of anti-herpes nucleosides has been made by the advent of 5-substituted pyrimidine nucleosides such as 5-iodo-, 5-ethyl-, 5-(2-chloroethyl)-, and (E)-5-(2-bromovinyl)- derivatives of 2'-deoxyuridine. These are highly specific inhibitors of HSV-1, HSV-2, and/or VZV infections. However, Epstein Barr virus (EBV) and HCMV are much less sensitive to these agents. In 5-substituted pyrimidine nucleosides the nature of substituents, particularly at the C-5 position, has been found to be an important determinant of anti-herpes activity. Structural requirements at the C-2 carbon of the 5

  5. Docking Studies, Synthesis, Characterization and Evaluation of Their Antioxidant and Cytotoxic Activities of Some Novel Isoxazole-Substituted 9-Anilinoacridine Derivatives

    PubMed Central

    Kalirajan, R.; Rafick, M. H. Mohammed; Sankar, S.; Jubie, S.

    2012-01-01

    A convenient synthesis of novel isoxazole-substituted 9-anilinoacridine derivatives 5a–j was reported. The compounds were confirmed by physical and analytical data and screened for in vitro antioxidant activity by DPPH method, reducing power assay and total antioxidant capacity method. The cytotoxic activity of the compounds was also studied in HEp-2 cell line. The docking studies of the synthesized compounds were performed towards the key nucleoside dsDNA by using AutoDock vina 4.0 programme. All the isoxazole-substituted compounds have significant activities. PMID:22593663

  6. Heterocyclic chalcone analogues as potential anticancer agents.

    PubMed

    Sharma, Vikas; Kumar, Vipin; Kumar, Pradeep

    2013-03-01

    Chalcones, aromatic ketones and enones acting as the precursor for flavonoids such as Quercetin, are known for their anticancer effects. Although, parent chalcones consist of two aromatic rings joined by a three-carbon α,β-unsaturated carbonyl system, various synthetic compounds possessing heterocyclic rings like pyrazole, indole etc. are well known and proved to be effective anticancer agents. In addition to their use as anticancer agents in cancer cell lines, heterocyclic analogues are reported to be effective even against resistant cell lines. In this connection, we hereby highlight the potential of various heterocyclic chalcone analogues as anticancer agents with a brief summary about therapeutic potential of chalcones, mechanism of anticancer action of various chalcone analogues, and current and future prospects related to the chalcones-derived anticancer research. Furthermore, some key points regarding chalcone analogues have been reviewed by analyzing their medicinal properties. PMID:22721390

  7. Natural variants of cytotoxic epitopes are T-cell receptor antagonists for antiviral cytotoxic T cells

    NASA Astrophysics Data System (ADS)

    Bertoletti, Antonio; Sette, Alessandro; Chisari, Francis V.; Penna, Amalia; Levrero, Massimo; Carli, Marco De; Fiaccadori, Franco; Ferrari, Carlo

    1994-06-01

    IT has been suggested that mutations within immunodominant cytotoxic T-lymphocyte (CTL) epitopes may be exploited by viruses to evade protective immune responses critical for clearance1-4. Viral escape could originate from passive mechanisms, such as mutations within crucial CTL epitopes, either affecting major histocompatibility complex binding or T-cell antigen receptor (TCR) recognition. Additionally, it has recently been shown that substitutions of TCR contact sites can yield analogue peptides that can still interact with the T-cell receptor but be unable to deliver a full stimulatory signal, thus inducing anergy5 or acting as an antagonist for the TCR6-8. We report here that hepatitis B virus isolates derived from two chronically infected patients display variant epitopes that act as natural TCR antagonists with the capacity to inhibit the CTL response to the wild-type epitope. During natural infection, TCR antagonist mutations of CTL epitopes could contribute to the development of viral persistence, especially if the antiviral CTL response is monospecific or the epitope is strongly immunodominant.

  8. Minor withanolides of Physalis longifolia: structure and cytotoxicity.

    PubMed

    Zhang, Huaping; Motiwala, Hashim; Samadi, Abbas; Day, Victor; Aubé, Jeffrey; Cohen, Mark; Kindscher, Kelly; Gollapudi, Rao; Timmermann, Barbara

    2012-01-01

    In our recent publication on bioactive guided isolation of compounds from Physalis longifolia (Solanaceae) novel anti-proliferative agents withalongolides A (4) and B (5), and their highly cytotoxic analogues, withalongolide A 4,19,27-triacetate (4a) and withalongolide B 4,19-diacetate (5a) were elucidated. In this study, the two lead compounds (4, 5) were re-isolated in gram quantities for the purpose of further analogue preparation and in vivo testing that would continue to probe structure-activity relationships. During this process, two additional withanolides, named withalongolides O (1) and P (2), were elucidated. Their structures were determined by spectroscopic techniques with 1 being subsequently confirmed by X-ray crystallographic analysis. Utilizing a MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] viability assay, withalongolide O (1) and its 4,7-diaceatate (1a), both containing the functionalities of Δ(2)-1-oxo- in A ring, a 5β,6β-epoxy in B ring, and a lactone ring in the nine-carbon side chain, exhibited potent cytotoxicity against human head and neck squamous cell carcinoma (JMAR and MDA-1986), melanoma (B16F10 and SKMEL-28), and normal fetal lung fibroblast (MRC-5) cells with IC(50) values in the range between 0.15 and 2.95 µM. In addition, the previously reported α orientation of 7-acetate group in acnistins C and D should be revised to the β orientation on the basis of NMR data comparison. PMID:23036966

  9. Minor Withanolides of Physalis longifolia: Structure and Cytotoxicity

    PubMed Central

    Zhang, Huaping; Motiwala, Hashim; Samadi, Abbas; Day, Victor; Aubé, Jeffrey; Cohen, Mark; Kindscher, Kelly; Gollapudi, Rao; Timmermann, Barbara

    2013-01-01

    In our recent publication on bioactive guided isolation of compounds from Physalis longifolia (Solanaceae) novel anti-proliferative agents withalongolides A (4) and B (5), and their highly cytotoxic analogues, withalongolide A 4,19,27-triacetate (4a) and withalongolide B 4,19-diacetate (5a) were elucidated. In this study, the two lead compounds (4, 5) were re-isolated in gram quantities for the purpose of further analogue preparation and in vivo testing that would continue to probe structure–activity relationships. During this process, two additional withanolides, named withalongolides O (1) and P (2), were elucidated. Their structures were determined by spectroscopic techniques with 1 being subsequently confirmed by X-ray crystallographic analysis. Utilizing a MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] viability assay, withalongolide O (1) and its 4,7-diaceatate (1a), both containing the functionalities of Δ2-1-oxo- in A ring, a 5β,6β-epoxy in B ring, and a lactone ring in the nine-carbon side chain, exhibited potent cytotoxicity against human head and neck squamous cell carcinoma (JMAR and MDA-1986), melanoma (B16F10 and SKMEL-28), and normal fetal lung fibroblast (MRC-5) cells with IC50 values in the range between 0.15 and 2.95 μM. In addition, the previously reported α orientation of 7-acetate group in acnistins C and D should be revised to the β orientation on the basis of NMR data comparison. PMID:23036966

  10. Selective Phosphorylation of South and North-Cytidine and Adenosine Methanocarba-Nucleosides by Human Nucleoside and Nucleotide Kinases Correlates with Their Growth Inhibitory Effects on Cultured Cells.

    PubMed

    Sjuvarsson, Elena; Marquez, Victor E; Eriksson, Staffan

    2015-01-01

    Here bicyclo[3.1.0]hexane locked deoxycytidine (S-MCdC, N-MCdC), and deoxyadenosine analogs (S-MCdA and N-MCdA) were examined as substrates for purified preparations of human deoxynucleoside kinases: dCK, dGK, TK2, TK1, the ribonucleoside kinase UCK2, two NMP kinases (CMPK1, TMPK) and a NDP kinase. dCK can be important for the first step of phosphorylation of S-MCdC in cells, but S-MCdCMP was not a substrate for CMPK1, TMPK, or NDPK. dCK and dGK had a preference for the S-MCdA whereas N-MCdA was not a substrate for dCK, TK1, UCK2, TK2, dGK nucleoside kinases. The cell growth experiments suggested that N-MCdC and S-MCdA could be activated in cells by cellular kinases so that a triphosphate metabolite was formed. List of abbreviations: ddC, 2', 3'-didioxycytosine, Zalcitabine; 3TC, β-L-(-)-2',3'-dideoxy-3'-thiacytidine, Lamivudine; CdA, 2-cloro-2'-deoxyadenosine, Cladribine; AraA, 9-β-D-arabinofuranosyladenine; hCNT 1-3, human Concentrative Nucleoside Transporter type 1, 2 and 3; hENT 1-4, human Equilibrative Nucleoside Transporter type 1, 2, 3, and 4. PMID:26167664

  11. Synthesis and SAR of vinca alkaloid analogues.

    PubMed

    Voss, Matthew E; Ralph, Jeffery M; Xie, Dejian; Manning, David D; Chen, Xinchao; Frank, Anthony J; Leyhane, Andrew J; Liu, Lei; Stevens, Jason M; Budde, Cheryl; Surman, Matthew D; Friedrich, Thomas; Peace, Denise; Scott, Ian L; Wolf, Mark; Johnson, Randall

    2009-02-15

    Versatile intermediates 12'-iodovinblastine, 12'-iodovincristine and 11'-iodovinorelbine were utilized as substrates for transition metal based chemistry which led to the preparation of novel analogues of the vinca alkaloids. The synthesis of key iodo intermediates, their transformation into final products, and the SAR based upon HeLa and MCF-7 cell toxicity assays is presented. Selected analogues 27 and 36 show promising anticancer activity in the P388 murine leukemia model. PMID:19147348

  12. Cellular effects of deoxynojirimycin analogues: uptake, retention and inhibition of glycosphingolipid biosynthesis

    PubMed Central

    2004-01-01

    Deoxynojirimycin (DNJ) analogues are inhibitors of ceramide glucosyltransferase (CGT), which catalyses the first step in the glucosphingolipid (GSL) biosynthetic pathway. We have synthesized a series of DNJ analogues to study the contribution of N-alk(en)yl side chains (C4, C9 or C18) to the behaviour of these analogues in cultured HL60 cells. When cells were treated for 16 h at non-cytotoxic concentrations of inhibitor, a 40–50% decrease in GSL levels was measured by HPLC analysis of GSL-derived oligosaccharides following ceramide glycanase digestion of GSL and 2-aminobenzamide labelling of the released oligosaccharides. Using a novel technique for short-term [14C]galactose labelling of cellular GSL, we used compound inhibition of GSL biosynthesis as a marker for compound uptake into cells. Surprisingly, the uptake of all three of the DNJ analogues was extremely rapid and was not dependent upon the length of the N-alk(en)yl moiety. Compound uptake occurred in less than 1 min, as shown by the complete inhibition of GSL labelling in cells treated with all the DNJ analogues. Greatly increased cellular retention of N-cis-13-octadecenyl-DNJ was observed relative to the shorter-chain compounds, N-butyl-DNJ and N-nonyl-DNJ, as indicated by complete inhibition of CGT 24 h after removal of inhibitor from the culture medium. The present study further characterizes the properties of N-alk(en)ylated DNJs, and demonstrates that increasing the length of the side chain is a simple way of improving imino sugar retention and therefore inhibitory efficacy for CGT in cultured cells. PMID:15128268

  13. Design, synthesis, and biological evaluation of dibromotyrosine analogues inspired by marine natural products as inhibitors of human prostate cancer proliferation, invasion, and migration.

    PubMed

    Sallam, Asmaa A; Ramasahayam, Sindhura; Meyer, Sharon A; El Sayed, Khalid A

    2010-11-01

    Bioactive secondary metabolites originating from dibromotyrosine are common in marine sponges, such as sponges of the Aplysina species. Verongiaquinol (1), 3,5-dibromo-1-hydroxy-4-oxocyclohexa-2,5-diene-1-acetamide, and aeroplysinin-1 are examples of such bioactive metabolites. Previous studies have shown the potent antimicrobial as well as cytotoxic properties of verongiaquinol and the anti-angiogenic activity of aeroplysinin-1. The work presented herein shows the design and synthesis of dibromotyrosine-inspired phenolic ester and ether analogues with anti-angiogenic, anti-proliferative and anti-migratory properties and negligible cytotoxicity. Several analogues were synthesized based on docking experiments in the ATP binding site of VEGFR2 and their anti-angiogenic potential and ability to inhibit angiogenesis and prostate cancer proliferation, migration and invasion were evaluated using the chick chorioallantoic membrane (CAM) assay, MTT, wound-healing, and Cultrex® BME cell invasion assay models, respectively. Analogues with high docking scores showed promising anti-angiogenic activity in the CAM assay. In general, ester analogues (5, 6, and 8-10) proved to be of higher anti-migratory activity whereas ether analogues (11-14) showed better anti-proliferative activity. These results demonstrate the potential of dibromotyrosines as promising inhibitory scaffolds for the control of metastatic prostate cancer proliferation and migration. PMID:20884214

  14. The Ugi reaction in the generation of new nucleosides as potential antiviral and antileishmanial agents.

    PubMed

    Fan, Xuesen; Zhang, Xinying; Bories, Christian; Loiseau, Philippe M; Torrence, Paul F

    2007-04-01

    5-Formyl-2'-deoxyuridine-3',5'-diacetate was converted to a small library of 5-substituted pyrimidine nucleoside N-acylamino acid amides by means of a Ugi multicomponent reaction. The reaction allowed introduction of various substituents at the acyl moiety, at the amino acid alpha-amide group, and at the amino acid carboxyl function. Evaluation of these novel 5-substituted nucleosides against vaccinia virus and cowpox virus provided one compound with discernable activity against cowpox virus but five- to eightfold less active than the Cidofovir standard. More promising activity was seen for the inhibition of Leishmania donovani promastigotes. Several synthetic products showed antileishmanial activity in the 10(-5)M range. When compared to earlier studies demonstrating anti-orthopoxviral and antileishmanial activity of 5-substituted pyrimidine nucleosides, these results imply that the 5-(N-acylamino acid amide)-derivatized pyrimidine nucleosides may possess more steric bulk, greater hydrophobicity, and more flexibility than is compatible with these particular biological activities. PMID:16996561

  15. Chemical synthesis of nucleoside-gamma-[32P]triphosphates of high specific activity.

    PubMed

    Janecka, A; Panusz, H; Pankowski, J; Koziołkiewicz, W

    1980-01-01

    A simple chemical procedure for the preparation of four common ribonucleoside 5-gamma-[32P]triphosphates of high specific activity (up to 10 Ci/mmole) based on the condensation of orthophosphoric acid with the corresponding nucleoside 5-diphosphate in the presence of ethyl chloroformate as well as the methods of purification and identification of the products are described. PMID:7375446

  16. Structural and functional characterization of a noncanonical nucleoside triphosphate pyrophosphatase from Thermotoga maritima

    SciTech Connect

    Awwad, Khaldeyah; Desai, Anna; Smith, Clyde; Sommerhalter, Monika

    2013-02-01

    A 2.15 Å resolution crystal structure of TM0159 with bound IMP and enzyme-kinetic data are presented. This noncanonical nucleoside triphosphatase from T. maritima helps to maintain a correct pool of DNA and RNA precursor molecules. The hyperthermophilic bacterium Thermotoga maritima has a noncanonical nucleoside triphosphatase that catalyzes the conversion of inosine triphosphate (ITP), deoxyinosine triphosphate (dITP) and xanthosine triphosphate (XTP) into inosine monophosphate (IMP), deoxyinosine monophosphate (IMP) and xanthosine monophosphate (XMP), respectively. The k{sub cat}/K{sub m} values determined at 323 and 353 K fall between 1.31 × 10{sup 4} and 7.80 × 10{sup 4} M{sup −1} s{sup −1}. ITP and dITP are slightly preferred over XTP. Activity towards canonical nucleoside triphosphates (ATP and GTP) was not detected. The enzyme has an absolute requirement for Mg{sup 2+} as a cofactor and has a preference for alkaline conditions. A protein X-ray structure of the enzyme with bound IMP was obtained at 2.15 Å resolution. The active site houses a well conserved network of residues that are critical for substrate recognition and catalysis. The crystal structure shows a tetramer with two possible dimer interfaces. One of these interfaces strongly resembles the dimer interface that is found in the structures of other noncanonical nucleoside pyrophosphatases from human (human ITPase) and archaea (Mj0226 and PhNTPase)

  17. Antiproliferative activity of bicyclic benzimidazole nucleosides: synthesis, DNA-binding and cell cycle analysis.

    PubMed

    Sontakke, Vyankat A; Lawande, Pravin P; Kate, Anup N; Khan, Ayesha; Joshi, Rakesh; Kumbhar, Anupa A; Shinde, Vaishali S

    2016-04-26

    An efficient route was developed for synthesis of bicyclic benzimidazole nucleosides from readily available d-glucose. The key reactions were Vörbruggen glycosylation and ring closing metathesis (RCM). Primarily, to understand the mode of DNA binding, we performed a molecular docking study and the binding was found to be in the minor groove region. Based on the proposed binding model, UV-visible and fluorescence spectroscopic techniques using calf thymus DNA (CT-DNA) demonstrated a non-intercalative mode of binding. Antiproliferative activity of nucleosides was tested against MCF-7 and MDA-MB-231 breast cancer cell lines and found to be active at low micromolar concentrations. Compounds and displayed significant antiproliferative activity as compared to and with the reference anticancer drug, doxorubicin. Cell cycle analysis showed that nucleoside induced cell cycle arrest at the S-phase. Confocal microscopy has been performed to validate the induction of cellular apoptosis. Based on these findings, such modified bicyclic benzimidazole nucleosides will make a significant contribution to the development of anticancer drugs. PMID:27074628

  18. Purification and characterization of purine nucleoside phosphorylase from developing embryos of Hyalomma dromedarii.

    PubMed

    Kamel, M Y; Fahmy, A S; Ghazy, A H; Mohamed, M A

    1991-04-01

    Purine nucleoside phosphorylase from Hyalomma dromedarii, the camel tick, was purified to apparent homogeneity. A molecular weight of 56,000 - 58,000 was estimated for both the native and denatured enzyme, suggesting that the enzyme is monomeric. Unlike purine nucleoside phosphorylase preparations from other tissues, the H. dromedarii enzyme was unstable in the presence of beta-mercaptoethanol. The enzyme had a sharp pH optimum at pH 6.5. It catalyzed the phosphorolysis and arsenolysis of ribo- and deoxyribo-nucleosides of hypoxanthine and guanine, but not of adenine or pyrimidine nucleosides. The Km values of the enzyme at the optimal pH for inosine, deoxyinosine, guanosine, and deoxyguanosine were 0.31, 0.67, 0.55, and 0.33 mM, respectively. Inactivation and kinetic studies suggested that histidine and cysteine residues were essential for activity. The pKa values determined for catalytic ionizable groups were 6-7 and 8-9. The enzyme was completely inactivated by thiol reagents and reactivated by excess beta-mercaptoethanol. The enzyme was also susceptible to pH-dependent photooxidation in the presence of methylene blue, implicating histidine. Initial velocity studies showed an intersecting pattern of double-reciprocal plots of the data, consistent with a sequential mechanism. PMID:1905141

  19. Nucleoside diphosphate kinase of Saccharomyces cerevisiae, Ynk1p: localization to the mitochondrial intermembrane space.

    PubMed Central

    Amutha, Boominathan; Pain, Debkumar

    2003-01-01

    Nucleoside diphosphate kinase (NDPK) is a highly conserved multifunctional enzyme. It catalyses the transfer of gamma phosphates from nucleoside triphosphates to nucleoside diphosphates by a mechanism that involves formation of an autophosphorylated enzyme intermediate. The phosphate is usually supplied by ATP. NDPK activity in different subcellular compartments may regulate the crucial balance between ATP and GTP or other nucleoside triphosphates. NDPKs are homo-oligomeric proteins and are predominantly localized in the cytosol. In this paper, we demonstrate that in Saccharomyces cerevisiae a small fraction of total NDPK activity encoded by YNK1 is present in the intermembrane space (IMS) of mitochondria, and the corresponding protein Ynk1p in the IMS represents approx. 0.005% of total mitochondrial proteins. Ynk1p, synthesized as a single gene product, must therefore be partitioned between cytoplasm and mitochondrial IMS fractions. A mechanism for this partitioning is suggested by our observations that interaction with a 40 kDa protein of the translocase of outer mitochondrial membrane (Tom40p), occurs preferentially with unfolded, unphosphorylated forms of Ynk1p. A population of newly translated, but not yet folded or autophosphorylated, Ynk1p intermediates may be imported into the IMS of mitochondria and trapped there by subsequent folding and oligomerization. Within the small volume of the IMS, Ynk1p may be more concentrated and may be required to supply GTP to several important proteins in this compartment. PMID:12472466

  20. Hypoxanthine enters human vascular endothelial cells (ECV 304) via the nitrobenzylthioinosine-insensitive equilibrative nucleoside transporter.

    PubMed Central

    Osses, N; Pearson, J D; Yudilevich, D L; Jarvis, S M

    1996-01-01

    The transport properties of the nucleobase hypoxanthine were examined in the human umbilical vein endothelial cell line ECV 304. Initial rates of hypoxanthine influx were independent of extracellular cations: replacement of Na+ with Li+, Rb+, N-methyl-D-glucamine or choline had no significant effect on hypoxanthine uptake by ECV 304 cells. Kinetic analysis demonstrated the presence of a single saturable system for the transport of hypoxanthine in ECV 304 cells with an apparent K(m) of 320 +/- 10 microM and a Vmax of 5.6 +/- 0.9 pmol/10(6) cells per s. Hypoxanthine uptake was inhibited by the nucleosides adenosine, uridine and thymidine (apparent Ki 41 +/- 6, 240 +/- 27 and 59 +/- 8 microM respectively) and the nucleoside transport inhibitors nitrobenzylthioinosine (NBMPR), dilazep and dipyridamole (apparent Ki 2.5 +/- 0.3, 11 +/- 3 and 0.16 +/- 0.006 microM respectively), whereas the nucleobases adenine, guanine and thymine had little effect (50% inhibition at > 1 mM). ECV 304 cells were also shown to transport adenosine via both the NBMPR-sensitive and -insensitive nucleoside carriers. Hypoxanthine specifically inhibited adenosine transport via the NBMPR-insensitive system in a competitive manner (apparent Ki 290 +/- 14 microM). These results indicate that hypoxanthine entry into ECV 304 endothelial cells is mediated by the NBMPR-insensitive nucleoside carrier present in these cells. PMID:8760371

  1. Release of nucleosides from canine and human hearts as an index of prior ischemia.

    PubMed

    Fox, A C; Reed, G E; Meilman, H; Silk, B B

    1979-01-01

    During ischemia, myocardial adenosine triphosphate is degraded to adenosine, inosine and hypoxanthine. These nucleosides are released into coronary venous blood and may provide an index of ischemia; adenosine may also participate in the autoregulation of coronary flow. In dogs, the temporal relations between reactive hyperemic flow and nucleoside concentrations in regional venous blood were correlated after brief occlusions of a segmental coronary artery. Reactive hyperemia and adenosine release peaked together in 10 seconds, persisted for 10 to 30 seconds and then decreased in a pattern consistent with the hypothesis that they are related. During initial reflow after 45 seconds of ischemia, mean concentrations of adenosine, inosine and hypoxanthine increased, respectively, to 52, 67 and 114 nmol/100 ml plasma; after 5 minutes of ischemia, the respective levels increased to 58, 1,570 and 1,134 nmol and fell quickly. In nine patients there was a similar release of nucleosides into coronary sinus blood during reperfusion after 59 to 80 minutes of ischemic arrest during cardiac surgery. With initial reflow, adenosine, inosine and hypoxanthine levels reached 65, 655 and 917 nmol/100 ml of blood, respectively. Inosine and hypoxanthine concentrations remained high for 5 to 10 minutes after cardiac beating resumed, often when production of lactate had decreased. The results indicate that postischemic release of nucleosides reaches significant levels in man as well as animals, is parallel with the duration of ischemia, is temporary and may be a useful supplement to measurement of lactate as an index of prior myocardial ischemia. PMID:758770

  2. Chemical and enzymatic reductive activation of acylfulvene to isomeric cytotoxic reactive intermediates

    PubMed Central

    Pietsch, Kathryn E.; Neels, James F.; Yu, Xiang; Gong, Jiachang; Sturla, Shana J.

    2011-01-01

    Acylfulvenes, a class of semisynthetic analogues of the sesquiterpene natural product illudin S, are cytotoxic towards cancer cells. The minor structural changes between illudin S and AFs translate to an improved therapeutic window in preclinical cell-based assays and xenograft models. AFs are, therefore, unique tools for addressing the chemical and biochemical basis of cytotoxic selectivity. AFs elicit cytotoxic responses by alkylation of biological targets, including DNA. While AFs are capable of direct alkylation, cytosolic reductive bioactivation to an electrophilic intermediate is correlated with enhanced cytotoxicity. Data obtained in this study illustrates chemical aspects of the process of AF activation. By tracking reaction mechanisms with stable isotope-labeled reagents, enzymatic versus chemical activation pathways for AF were compared for reactions involving the NADPH-dependent enzyme prostaglandin reductase 1 (PTGR1) or sodium borohydride, respectively. These two processes resulted in isomeric products that appear to give rise to similar patterns of DNA modification. The chemically activated isomer has been newly isolated and chemically characterized in this study, including an assessment of its relative stereochemistry, and stability at varying pH and under bioassay conditions. In mammalian cancer cells, this chemically activated analog was shown to not rely on further cellular activation to significantly enhance cytotoxic potency, in contrast to the requirements of AF. On the basis of this study, we anticipate that the chemically activated form of AF will serve as a useful chemical probe for evaluating biomolecular interactions independent of enzyme-mediated activation. PMID:21939268

  3. Donor/acceptor chromophores-decorated triazolyl unnatural nucleosides: synthesis, photophysical properties and study of interaction with BSA.

    PubMed

    Bag, Subhendu Sekhar; Talukdar, Sangita; Das, Suman Kalyan; Pradhan, Manoj Kumar; Mukherjee, Soumen

    2016-06-14

    Much effort has been put forth to develop unnatural, stable, hydrophobic base pairs with orthogonal recognition properties and study their effect on DNA duplex stabilisation. Our continuous efforts on the design of fluorescent unnatural biomolecular building blocks lead us to the synthesis of some triazolyl donor/acceptor unnatural nucleosides via an azide-alkyne 1,3-dipolar cycloaddition reaction as a key step, which we want to report herein. We have studied their photophysical properties and found interesting solvatochromic fluorescence for two of the nucleosides. Photophysical interactions among two donor-acceptor β-nucleosides as well as a pair of α/β-nucleosides have also been evaluated. Furthermore, we have exploited one of the fluorescent nucleosides in studying its interaction with BSA with the help of UV-visible and steady state fluorescence techniques. Our design concept is based on the hypothesis that a pair of such donor/acceptor nucleosides might be involved in π-stacking as well as in photophysical interactions, leading to stabilization of the DNA duplex if such nucleosides can be incorporated into short oligonucleotide sequences. Therefore, the designed bases may find application in biophysical studies in the context of DNA. PMID:27181694

  4. Base release in nucleosides induced by low-energy electrons: a DFT study.

    PubMed

    Li, Xifeng; Sanche, Léon; Sevilla, Michael D

    2006-06-01

    Low-energy electrons are known to induce strand breaks and base damage in DNA and RNA through fragmentation of molecular bonding. Recently the glycosidic bond cleavage of nucleosides by low-energy electrons has been reported. These experimental results call for a theoretical investigation of the strength of the C(1)'-N link in nucleosides (dA, dC and dT) between the base and deoxyribose before and after electron attachment. Through density functional theory (DFT) calculations, we compare the C(1)'-N bond strength, i.e., the bond dissociation energy of the neutral and its anionic radical, and find that an excess electron effectively weakens the C(1)'- N bond strength in nucleosides by 61-75 kcal/mol in the gas phase and 76-83 kcal/mol in the solvated environment. As a result, electron-induced fragmentation of the C(1)'-N bond in the gas phase is exergonic for dA (DeltaG=-14 kcal/mol) and for dT (DeltaG=-6 kcal/mol) and is endergonic (DeltaG=+1 kcal/ mol) only for dC. In the gas phase all the anionic nucleosides are found to be in valence states. Solvation is found to increase the exergonic nature by an additional 20 kcal, making the fragmentation both exothermic and exergonic for all nucleoside anion radicals. Thus C(1)'-N bond breaking in nucleoside anion radicals is found to be thermodynamically favorable both in the gas phase and under solvation. The activation barrier for the C(1)'-N bond breaking process was found to be about 20 kcal/mol in every case examined, suggesting that a 1 eV electron would induce spontaneous cleavage of the bond and that stabilized anion radicals on the DNA strand would undergo base release at only a modest rate at room temperature. These results suggest that base release from nucleosides and DNA is an expected consequence of low-energy electron-induced damage but that the high barrier would inhibit this process in the stable anion radicals. PMID:16802873

  5. Planetary habitability: lessons learned from terrestrial analogues

    NASA Astrophysics Data System (ADS)

    Preston, Louisa J.; Dartnell, Lewis R.

    2014-01-01

    Terrestrial analogue studies underpin almost all planetary missions and their use is essential in the exploration of our Solar system and in assessing the habitability of other worlds. Their value relies on the similarity of the analogue to its target, either in terms of their mineralogical or geochemical context, or current physical or chemical environmental conditions. Such analogue sites offer critical ground-truthing for astrobiological studies on the habitability of different environmental parameter sets, the biological mechanisms for survival in extreme environments and the preservation potential and detectability of biosignatures. The 33 analogue sites discussed in this review have been selected on the basis of their congruence to particular extraterrestrial locations. Terrestrial field sites that have been used most often in the literature, as well as some lesser known ones which require greater study, are incorporated to inform on the astrobiological potential of Venus, Mars, Europa, Enceladus and Titan. For example, the possibility of an aerial habitable zone on Venus has been hypothesized based on studies of life at high-altitudes in the terrestrial atmosphere. We also demonstrate why many different terrestrial analogue sites are required to satisfactorily assess the habitability of the changing environmental conditions throughout Martian history, and recommend particular sites for different epochs or potential niches. Finally, habitable zones within the aqueous environments of the icy moons of Europa and Enceladus and potentially in the hydrocarbon lakes of Titan are discussed and suitable analogue sites proposed. It is clear from this review that a number of terrestrial analogue sites can be applied to multiple planetary bodies, thereby increasing their value for astrobiological exploration. For each analogue site considered here, we summarize the pertinent physiochemical environmental features they offer and critically assess the fidelity with which

  6. Expression of nucleoside transporter in freshly isolated neurons and astrocytes from mouse brain.

    PubMed

    Li, B; Gu, L; Hertz, L; Peng, L

    2013-11-01

    Nucleoside transporters comprise equilibrative ENT1-4 and concentrative CNT1-3. CNTs transport against an intracellular/extracellular gradient and are essential for transmitter removal, independently of metabolic need. ENT1-4 mediate transport until intracellular/extracellular equilibrium of the transported compound, but are very efficient, when the accumulated nucleoside or nucleobase is rapidly eliminated by metabolism. Most nucleoside transporters are membrane-bound, but ENT3 is mainly intracellular. This study uses freshly isolated neurons and astrocytes from two adult mouse strains. In one transgenic strain the neuronal marker Thy1 was associated with a compound fluorescing at one wavelength, and in the other the astrocytic marker GFAP was associated with a compound fluorescent at a different wavelength. Highly purified astrocytic and neuronal populations (as determined by presence/absence of cell-specific genes) were obtained from these mice by fluorescence-activated cell sorting. In each population mRNA analysis was performed by reverse-transcription polymerase chain reaction. CNT1 was absent in both cell types; all other nucleoside transporters were expressed to at least a similar degree (in relation to applied amount of RNA and to a house-keeping gene) in astrocytes as in neurons. Astrocytic ENT3 enrichment was dramatic, but it was not up-regulated after fluoxetine-mediated increase in DNA synthesis. A comparison with results obtained in cultured astrocytes shows that the latter are generally compatible with the present findings and suggests that many observations obtained in intact tissue, mainly by in situ hybridization (which also determines mRNA expression) may underestimate astrocytic nucleoside transporter expression. PMID:24026568

  7. Reduced Ribavirin Antiviral Efficacy via Nucleoside Transporter-Mediated Drug Resistance▿

    PubMed Central

    Ibarra, Kristie D.; Pfeiffer, Julie K.

    2009-01-01

    Treatment for hepatitis C virus infection currently consists of pegylated interferon and ribavirin (RBV), a nucleoside analog. Although RBV clearly plays a role in aiding the treatment response, its antiviral mechanism is unclear. Regardless of the specific mechanism of RBV, we hypothesize that differences in levels of cellular uptake of RBV may affect antiviral efficacy and treatment success and that cells may become RBV resistant through reduced uptake. We monitored RBV uptake in various cell lines and determined the effect of uptake capacity on viral replication. RBV-resistant cells demonstrated reduced RBV uptake and increased growth of a model RNA virus, poliovirus, in the presence of RBV. Overexpression of equilibrative nucleoside transporter 1 (ENT1) or concentrative nucleoside transporter 3 (CNT3) increased RBV uptake in RBV-sensitive cell lines and restored the uptake defect in most RBV-resistant cell lines. However, CNT3 is not expressed in Huh-7 liver cells, and inhibition of concentrative transport did not affect RBV uptake. Blocking equilibrative transport using the inhibitor nitrobenzylmercaptopurine riboside recapitulated the RBV-resistant phenotype in RBV-sensitive cell lines, with a reduction in RBV uptake and increased poliovirus growth. Taken together, these results indicate that RBV uptake is restricted primarily to ENT1 in the cell lines examined. Interestingly, some RBV-resistant cell lines may compensate for reduced ENT1-mediated nucleoside uptake by increasing the activity of an alternative nucleoside transporter, ENT2. It is possible that RBV uptake affects the antiviral treatment response, either through natural differences in patients or through acquired resistance. PMID:19244331

  8. Potent Cytotoxic Arylnaphthalene Lignan Lactones from Phyllanthus poilanei

    PubMed Central

    2015-01-01

    Two new (1 and 2) and four known arylnaphthalene lignan lactones (3–6) were isolated from different plant parts of Phyllanthus poilanei collected in Vietnam, with two further known analogues (7 and 8) being prepared from phyllanthusmin C (4). The structures of the new compounds were determined by interpretation of their spectroscopic data and by chemical methods, and the structure of phyllanthusmin D (1) was confirmed by single-crystal X-ray diffraction analysis. Several of these arylnaphthalene lignan lactones were cytotoxic toward HT-29 human colon cancer cells, with compounds 1 and 7-O-[(2,3,4-tri-O-acetyl)-α-l-arabinopyranosyl)]diphyllin (7) found to be the most potent, exhibiting IC50 values of 170 and 110 nM, respectively. Compound 1 showed activity when tested in an in vivo hollow fiber assay using HT-29 cells implanted in immunodeficient NCr nu/nu mice. Mechanistic studies showed that this compound mediated its cytotoxic effects by inducing tumor cell apoptosis through activation of caspase-3, but it did not inhibit DNA topoisomerase IIα activity. PMID:24937209

  9. Antimicrobial and cytotoxicity potential of acetamido, amino and nitrochalcones.

    PubMed

    Tristão, T C; Campos-Buzzi, F; Corrêa, R; Cruz, R C B; Cechinel Filho, V; Bella Cruz, A

    2012-12-01

    Chalcones constitute one of the major classes of natural products belonging to the flavonoid family, and they have been reported as having a range of important therapeutic activities, including some chalcones are effective as antimicrobial agents. Currently, the search for new structures with antimicrobial activity has been intensified due to the emergence of many strains resistant to antibiotics currently used to treat infectious diseases.3 chalcone series (amino, acetamido and nitrochalcones) were prepared (23 compounds) and evaluated for their antimicrobial and cytotoxic potential. The effects of substituents on their respective activities also was evaluated.The results showed that 4 aminochalcones (2, 4, 8, 9), 3 acetoamidochalcones (10, 14, 18) and 3 nitrochalcones (20, 22, 23), exhibited antifungal effects. The aminochalcones were more toxic than the acetamidochalcones, while the nitrochalcones did not present any toxic effect. It was verified that there seems to be structure-activity correlation in some electron-donating and withdrawing substituents groups in rings A and B of the synthetized chalcone analogues and its antifungal and cytotoxic activity. PMID:23086581

  10. Synthesis of nucleoside and nucleotide conjugates of bile acids, and polymerase construction of bile acid-functionalized DNA.

    PubMed

    Ikonen, Satu; Macícková-Cahová, Hana; Pohl, Radek; Sanda, Miloslav; Hocek, Michal

    2010-03-01

    Aqueous Sonogashira cross-coupling reactions of 5-iodopyrimidine or 7-iodo-7-deazaadenine nucleosides with bile acid-derived terminal acetylenes linked via an ester or amide tether gave the corresponding bile acid-nucleoside conjugates. Analogous reactions of halogenated nucleoside triphosphates gave directly bile acid-modified dNTPs. Enzymatic incorporation of these modified nucleotides to DNA was successfully performed using Phusion polymerase for primer extension. One of the dNTPs (dCTP bearing cholic acid) was also efficient for PCR amplification. PMID:20165813

  11. Farnesides A and B, Sesquiterpenoid Nucleoside Ethers from a Marine-Derived Streptomyces sp., strain CNT-372 from Fiji

    PubMed Central

    Ilan, Ella Zafrir; Torres, Manuel R.; Prudhomme, Jacques; Le Roch, Karine; Jensen, Paul R.; Fenical, William

    2013-01-01

    Farnesides A and B (1, 2), linear sesquiterpenoids connected by ether links to a ribose dihydrouracil nucleoside, were isolated from a marine-derived Streptomyces sp., strain CNT-372, grown in saline liquid culture. The structures of the new compounds were assigned by comprehensive spectroscopic analysis primarily involving 1D and 2D NMR analysis and by comparison of spectroscopic data to the recently reported ribose nucleoside JBIR-68 (3). The farnesides are only the second example of this exceedingly rare class of microbial terpenoid nucleoside metabolites. Farneside A (1) was found to have modest antimalarial activity against the parasite Plasmodium falciparum. PMID:23987585

  12. The reversible DNA-alkylating activity of duocarmycin and its analogues.

    PubMed Central

    Asai, A; Nagamura, S; Saito, H; Takahashi, I; Nakano, H

    1994-01-01

    Intact drugs with spirocyclopropylhexadienone moieties can be regenerated from the covalent DNA adducts induced by antitumor antibiotics duocarmycin (DUM) A, SA and some DUMA analogues in neutral aqueous solution. We detected the reversible nature of DUMs by determination of the antimicrobial activity and cytotoxicity of DUM-DNA adducts. All of the adducts selectively inhibited the growth of a sensitive strain of Bacillus but not that of the wild type strain, a property of parent DUM and its analogues. Most of the DNA adducts were also cytotoxic to HeLa S3. These results suggested that active drugs can be released from their covalent DNA adducts under these biological assay conditions. Regeneration of intact drugs was quantitatively analyzed by HPLC and the amount of free drug released from DNA adducts revealed that the rate and efficiency of this reversal were dependent on structural variables among the drugs. The differences in rates of reversibility were correlated with the biological activity of DUMs. The effect of pH, temperature and salt concentration on the regeneration of drugs from their DNA adducts suggest a catalytic role of double-helical DNA on the reversal pathway. Images PMID:8127659

  13. Saponins as cytotoxic agents: a review

    PubMed Central

    Galanty, Agnieszka; Sobolewska, Danuta

    2010-01-01

    Saponins are natural glycosides which possess a wide range of pharmacological properties including cytotoxic activity. In this review, the recent studies (2005–2009) concerning the cytotoxic activity of saponins have been summarized. The correlations between the structure and the cytotoxicity of both steroid and triterpenoid saponins have been described as well as the most common mechanisms of action. PMID:20835386

  14. Glucagonlike Peptide 2 Analogue Teduglutide

    PubMed Central

    Chaturvedi, Lakshmi S.; Basson, Marc D.

    2015-01-01

    IMPORTANCE Short bowel syndrome occurs when a shortened intestine cannot absorb sufficient nutrients or fluids. Teduglutide is a recombinant analogue of human glucagonlike peptide 2 that reduces dependence on parenteral nutrition in patients with short bowel syndrome by promoting enterocytic proliferation, increasing the absorptive surface area. However, enterocyte function depends not only on the number of cells that are present but also on differentiated features that facilitate nutrient absorption and digestion. OBJECTIVE To test the hypothesis that teduglutide impairs human intestinal epithelial differentiation. DESIGN AND SETTING We investigated the effects of teduglutide in the modulation of proliferation and differentiation in human Caco-2 intestinal epithelial cells at a basic science laboratory. This was an in vitro study using Caco-2 cells, a human-derived intestinal epithelial cell line commonly used to model enterocytic biology. EXPOSURE Cells were exposed to teduglutide or vehicle control. MAINOUTCOMESAND MEASURES We analyzed the cell cycle by bromodeoxyuridine incorporation or propidium iodide staining and flow cytometry and measured cell proliferation by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. We used quantitative reverse transcription–polymerase chain reaction to assay the expression of the enterocytic differentiation markers villin, sucrase-isomaltase, glucose transporter 2 (GLUT2), and dipeptidyl peptidase 4 (DPP-4), as well as that of the putative differentiation signals schlafen 12 (SLFN12) and caudal-related homeobox intestine-specific transcription factor (Cdx2). Villin promoter activity was measured by a luciferase-based assay. RESULTS The MTS assay demonstrated that teduglutide increased cell numbers by a mean (SD) of 10% (2%) over untreated controls at a maximal 500nM (n = 6, P < .05). Teduglutide increased bromodeoxyuridine-positive cells vs untreated controls by a mean (SD

  15. (15)N NMR studies of a nitrile-modified nucleoside.

    PubMed

    Gillies, Anne T; Gai, Xin Sonia; Buckwalter, Beth L; Fenlon, Edward E; Brewer, Scott H

    2010-12-30

    Nitrile-modified molecules have proven to be excellent probes of local environments in biomolecules via both vibrational and fluorescence spectroscopy. The utility of the nitrile group as a spectroscopic probe has been expanded here to (15)N NMR spectroscopy by selective (15)N incorporation. The (15)N NMR chemical shift (δ((15)N)) of the (15)N-labeled 5-cyano-2'-deoxyuridine (C(15)NdU, 1a) was found to change from 153.47 to 143.80 ppm in going from THF-d(8) to D(2)O. A 0.81 ppm downfield shift was measured upon formation of a hydrogen-bond-mediated heterodimer between 2,6-diheptanamidopyridine and a silyl ether analogue of 1a in chloroform, and the small intrinsic temperature dependence of δ((15)N) of C(15)NdU was measured as a 0.38 ppm downfield shift from 298 to 338 K. The experiments were complemented with density functional theory calculations exploring the effect of solvation on the (15)N NMR chemical shift. PMID:21126044

  16. Robenidine Analogues as Gram-Positive Antibacterial Agents.

    PubMed

    Abraham, Rebecca J; Stevens, Andrew J; Young, Kelly A; Russell, Cecilia; Qvist, Anastasia; Khazandi, Manouchehr; Wong, Hui San; Abraham, Sam; Ogunniyi, Abiodun D; Page, Stephen W; O'Handley, Ryan; McCluskey, Adam; Trott, Darren J

    2016-03-10

    Robenidine, 1 (2,2'-bis[(4-chlorophenyl)methylene]carbonimidic dihydrazide), was active against MRSA and VRE with MIC's of 8.1 and 4.7 μM, respectively. SAR revealed tolerance for 4-Cl isosteres with 4-F (8), 3-F (9), 3-CH3 (22), and 4-C(CH3)3 (27) (23.7-71 μM) and with 3-Cl (3), 4-CH3 (21), and 4-CH(CH3)2 (26) (8.1-13.0 μM). Imine carbon alkylation identified a methyl/ethyl binding pocket that also accommodated a CH2OH moiety (75; 2,2'-bis[1-(4-chlorophenyl)-2-hydroxyethylidene]carbonimidic dihydrazide). Analogues 1, 27 (2,2'-bis{[4-(1,1-dimethylethyl)phenyl]methylene}carbonimidic dihydrazide), and 69 (2,2'-bis[1-(4-chlorophenyl)ethylidene]carbonimidic dihydrazide hydrochloride) were active against 24 clinical MRSA and MSSA isolates. No dose-limiting cytotoxicity at ≥2× MIC or hemolysis at ≥8× MIC was observed. Polymyxin B addition engendered Escherichia coli and Pseudomonas aeruginosa Gram-negative activity MIC's of 4.2-21.6 μM. 1 and 75 displayed excellent microsomal stability, intrinsic clearance, and hepatic extraction ratios with T1/2 > 247 min, CLint < 7 μL/min/mg protein, and EH < 0.22 in both human and mouse liposomes for 1 and in human liposomes for 75. PMID:26765953

  17. Synthesis and Biological Evaluation of Lactimidomycin and Its Analogues.

    PubMed

    Larsen, Brian J; Sun, Zhankui; Lachacz, Eric; Khomutnyk, Yaroslav; Soellner, Matthew B; Nagorny, Pavel

    2015-12-21

    The studies culminating in the total synthesis of the glutarimide-containing eukaryote translation elongation inhibitor lactimidomycin are described. The optimized synthetic route features a Zn(II)-mediated intramolecular Horner-Wadsworth-Emmons (HWE) reaction resulting in a highly stereoselective formation of the strained 12-membered macrolactone of lactimidomycin on a 423 mg scale. The presence of the E,Z-diene functionality was found to be key for effective macrocyclizations as a complete removal of these unsaturation units resulted in exclusive formation of the dimer rather than monocyclic enoate. The synthetic route features a late-stage installation of the glutarimide functionality via an asymmetric catalytic Mukaiyama aldol reaction, which allows for a quick generation of lactimidomycin homolog 55 containing two additional carbons in the glutarimide side chain. Similar to lactimidomycin, this analog was found to possess cytotoxicity against MDA-MB-231 breast cancer cells (GI50 =1-3 μM) using in vitro 2D and 3D assays. Although lactimidomycin was found to be the most potent compound in terms of anticancer activity, 55 as well as truncated analogues 50-52 lacking the glutarimide side-chain were found to be significantly less toxic against human mammary epithelial cells. PMID:26577990

  18. Biotinylated Platinum(II) Ferrocenylterpyridine Complexes for Targeted Photoinduced Cytotoxicity.

    PubMed

    Mitra, Koushambi; Shettar, Abhijith; Kondaiah, Paturu; Chakravarty, Akhil R

    2016-06-01

    Biotinylated platinum(II) ferrocenylterpyridine (Fc-tpy) complexes [Pt(Fc-tpy)(L(1))]Cl (1) and [Pt(Fc-tpy)(L(2))]Cl (2), where HL(1) and HL(2) are biotin-containing ligands, were prepared, and their targeted photoinduced cytotoxic effect in cancer cells over normal cells was studied. A nonbiotinylated complex, [Pt(Fc-tpy)(L(3))]Cl (3), was prepared as a control to study the role of the biotin moiety in cellular uptake properties of the complexes. Three platinum(II) phenylterpyridine (Ph-tpy) complexes, viz., [Pt(Ph-tpy)(L(1))]Cl (4), [Pt(Ph-tpy)(L(2))]Cl (5), and [Pt(Ph-tpy)(L(3))]Cl (6), were synthesized and explored to understand the role of a metal-bound Fc-tpy ligand over Ph-tpy as a photoinitiator. The Fc-tpy complexes displayed an intense absorption band near 640 nm, which was absent in their Ph-tpy analogues. The Fc-tpy complexes (1 mM in 0.1 M TBAP) showed an irreversible cyclic voltammetric anodic response of the Fc/Fc(+) couple near 0.25 V. The Fc-tpy complexes displayed photodegradation in red light of 647 nm involving the formation of a ferrocenium ion (Fc(+)) and reactive oxygen species (ROS). Photoinduced release of the biotinylated ligands was observed from spectral measurements, and this possibly led to the controlled generation of an active platinum(II) species, which binds to the calf-thymus DNA used for this study. The biotinylated photoactive Fc-tpy complexes showed significant photoinduced cytotoxicity, giving a IC50 value of ∼7 μM in visible light of 400-700 nm with selective uptake in BT474 cancer cells over HBL-100 normal cells. Furthermore, ferrocenyl complexes resulted in light-induced ROS-mediated apoptosis, as indicated by DCFDA, annexin V/FITC staining, and sub-G1 DNA content determined by fluorescent activated cell sorting analysis. The phenyl analogues 4 and 5 were photostable, served as DNA intercalators, and demonstrated selective cytotoxicity in the cancer cells, giving IC50 values of ∼4 μM. PMID:27171926

  19. Convergent syntheses of LeX analogues

    PubMed Central

    Wang, An; Hendel, Jenifer

    2010-01-01

    Summary The synthesis of three Lex derivatives from one common protected trisaccharide is reported. These analogues will be used respectively for competitive binding experiments, conjugation to carrier proteins and immobilization on gold. An N-acetylglucosamine monosaccharide acceptor was first glycosylated at O-4 with a galactosyl imidate. This coupling was performed at 40 °C under excess of BF3·OEt2 activation and proceeded best if the acceptor carried a 6-chlorohexyl rather than a 6-azidohexyl aglycon. The 6-chlorohexyl disaccharide was then converted to an acceptor and submitted to fucosylation yielding the corresponding protected 6-chlorohexyl Lex trisaccharide. This protected trisaccharide was used as a precursor to the 6-azidohexyl, 6-acetylthiohexyl and 6-benzylthiohexyl trisaccharide analogues which were obtained in excellent yields (70–95%). In turn, we describe the deprotection of these intermediates in one single step using dissolving metal conditions. Under these conditions, the 6-chlorohexyl and 6-azidohexyl intermediates led respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly efficient and convergent preparation of these three Lex analogues. PMID:20485599

  20. Downregulation of deoxycytidine kinase in cytarabine-resistant mantle cell lymphoma cells confers cross-resistance to nucleoside analogs gemcitabine, fludarabine and cladribine, but not to other classes of anti-lymphoma agents

    PubMed Central

    2014-01-01

    Background Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma associated with poor prognosis. Implementation of high-dose cytarabine (araC) into induction therapy became standard-of-care for all newly diagnosed younger MCL patients. However, many patients relapse even after araC-based regimen. Molecular mechanisms responsible for araC resistance in MCL are unknown and optimal treatment strategy for relapsed/refractory MCL patients remains elusive. Methods Five araC-resistant (R) clones were derived by long-term culture of five MCL cell lines (CTRL) with increasing doses of araC up to 50 microM. Illumina BeadChip and 2-DE proteomic analysis were used to identify gene and protein expression changes associated with araC resistance in MCL. In vitro cytotoxicity assays and experimental therapy of MCL xenografts in immunodeficient mice were used to analyze their relative responsiveness to a set of clinically used anti-MCL drugs. Primary MCL samples were obtained from patients at diagnosis and after failure of araC-based therapies. Results Marked downregulation of deoxycytidine-kinase (DCK) mRNA and protein expression was identified as the single most important molecular event associated with araC-resistance in all tested MCL cell lines and in 50% primary MCL samples. All R clones were highly (20-1000x) cross-resistant to all tested nucleoside analogs including gemcitabine, fludarabine and cladribine. In vitro sensitivity of R clones to other classes of clinically used anti-MCL agents including genotoxic drugs (cisplatin, doxorubicin, bendamustine) and targeted agents (bortezomib, temsirolimus, rituximab) remained unaffected, or was even increased (ibrutinib). Experimental therapy of immunodeficient mice confirmed the anticipated loss of anti-tumor activity (as determined by overall survival) of the nucleoside analogs gemcitabine and fludarabine in mice transplanted with R clone compared to mice transplanted with CTRL cells, while the anti