RESUMEN

Syntheses and antiviral activity of new carbocyclic analogs of 2', 3'-dideoxysangivamycin, 2',3'-dideoxytoyocamycin and 2',3'-dideoxytriciribine is described. The key intermediate, carbocyclic 4-chloro-5-iodopyrrolopyrimidine. was synthesized in good yield via a novel iodination method using I2 and CF3COOAg. This carbocyclic 4-chloro-5-iodopyrrolopyrimidine then allowed for a concise synthesis of the desired 4,5-disubstituted carbocyclic nucleosides.

Asunto(s)

Antivirales/síntesis química , Nucleósidos de Pirimidina/síntesis química , Ribonucleósidos/síntesis química , Toyocamicina/análogos & derivados , Toyocamicina/síntesis química , Antivirales/farmacología , Desoxirribonucleósidos/metabolismo , Desoxirribonucleósidos/farmacología , Espectroscopía de Resonancia Magnética , Modelos Químicos , Toyocamicina/farmacología

RESUMEN

Ziagen, (1S,cis)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]- 2-cyclopentene-1-methanol, was synthesized from (1S,4R)-azabicyclo[2.2.1]hept-5-en-3-one by efficient processes which bypass problematic steps in earlier routes. 2-Amino-4,6-dichloro-5-formamidopyrimidine is a key intermediate which makes possible an efficient construction of the purine from a chiral cyclopentenyl precursor.

Asunto(s)

Fármacos Anti-VIH/síntesis química , Didesoxinucleósidos/síntesis química , Inhibidores de la Transcriptasa Inversa/síntesis química , Cristalografía por Rayos X , Espectroscopía de Resonancia Magnética

RESUMEN

The potent activity of 2,5,6-trichloro-1-(beta-D-ribofuranosyl)benzimidazole (TCRB) against Human Cytomegalovirus with the concomitant low cellular toxicity at concentrations that inhibit viral growth prompted considerable interest in this research area. This interest was moderated by the pharmacokinetic studies of TCRB in rats and monkeys that revealed the instability of TCRB in vivo. These studies suggested that the instability was due to a cleavage of the glycosidic bond in vivo which released the heterocycle (2,5,6-trichlorobenzimidazole) into the bloodstream. This prompted us to initiate synthetic studies designed to increase the stability of the glycosidic bond of TCRB and BDCRB. Several synthetic approaches to address this and other problems are presented.

Asunto(s)

Antivirales/química , Antivirales/farmacología , Bencimidazoles/química , Bencimidazoles/farmacología , Citomegalovirus/efectos de los fármacos , Ribonucleósidos/química , Ribonucleósidos/farmacología , Animales , Haplorrinos , Pruebas de Sensibilidad Microbiana , Ratas

RESUMEN

1592U89, (-)-(1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclo pentene-1-methanol, is a carbocyclic nucleoside with a unique biological profile giving potent, selective anti-human immunodeficiency virus (HIV) activity. 1592U89 was selected after evaluation of a wide variety of analogs containing a cyclopentene substitution for the 2'-deoxyriboside of natural deoxynucleosides, optimizing in vitro anti-HIV potency, oral bioavailability, and central nervous system (CNS) penetration. 1592U89 was equivalent in potency to 3'-azido-3'-deoxythymidine (AZT) in human peripheral blood lymphocyte (PBL) cultures against clinical isolates of HIV type 1 (HIV-1) from antiretroviral drug-naive patients (average 50% inhibitory concentration [IC50], 0.26 microM for 1592U89 and 0.23 microM for AZT). 1592U89 showed minimal cross-resistance (approximately twofold) with AZT and other approved HIV reverse transcriptase (RT) inhibitors. 1592U89 was synergistic in combination with AZT, the nonnucleoside RT inhibitor nevirapine, and the protease inhibitor 141W94 in MT4 cells against HIV-1 (IIIB). 1592U89 was anabolized intracellularly to its 5'-monophosphate in CD4+ CEM cells and in PBLs, but the di- and triphosphates of 1592U89 were not detected. The only triphosphate found in cells incubated with 1592U89 was that of the guanine analog (-)-carbovir (CBV). However, the in vivo pharmacokinetic, distribution, and toxicological profiles of 1592U89 were distinct from and improved over those of CBV, probably because CBV itself was not appreciably formed from 1592U89 in cells or animals (<2%). The 5'-triphosphate of CBV was a potent, selective inhibitor of HIV-1 RT, with Ki values for DNA polymerases (alpha, beta, gamma, and epsilon which were 90-, 2,900-, 1,200-, and 1,900-fold greater, respectively, than for RT (Ki, 21 nM). 1592U89 was relatively nontoxic to human bone marrow progenitors erythroid burst-forming unit and granulocyte-macrophage CFU (IC50s, 110 microM) and human leukemic and liver tumor cell lines. 1592U89 had excellent oral bioavailability (105% in the rat) and penetrated the CNS (rat brain and monkey cerebrospinal fluid) as well as AZT. Having demonstrated an excellent preclinical profile, 1592U89 has progressed to clinical evaluation in HIV-infected patients.

Asunto(s)

Síndrome de Inmunodeficiencia Adquirida/tratamiento farmacológico , Fármacos Anti-VIH/farmacocinética , Didesoxinucleósidos/farmacocinética , Síndrome de Inmunodeficiencia Adquirida/metabolismo , Adenosina Desaminasa/metabolismo , Administración Oral , Animales , Fármacos Anti-VIH/sangre , Fármacos Anti-VIH/química , Fármacos Anti-VIH/orina , Antivirales/sangre , Antivirales/farmacocinética , Área Bajo la Curva , Biotransformación , Células Cultivadas , Didesoxinucleósidos/sangre , Didesoxinucleósidos/química , Didesoxinucleósidos/orina , Farmacorresistencia Microbiana , Femenino , VIH-1/efectos de los fármacos , Semivida , Humanos , Inyecciones Intravenosas , Macaca fascicularis , Masculino , Ratas , Relación Estructura-Actividad

RESUMEN

The anabolism of 1592U89, (-)-(1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclo pentene-1-methanol, a selective inhibitor of human immunodeficiency virus (HIV), was characterized in human T-lymphoblastoid CD4+ CEM cells. 1592U89 was ultimately anabolized to the triphosphate (TP) of the guanine analog (-)-carbovir (CBV), a potent inhibitor of HIV reverse transcriptase. However, less than 2% of intracellular 1592U89 was converted to CBV, an amount insufficient to account for the CBV-TP levels observed. 1592U89 was anabolized to its 5'-monophosphate (MP) by the recently characterized enzyme adenosine phosphotransferase, but neither its diphosphate (DP) nor its TP was detected. The MP, DP, and TP of CBV were found in cells incubated with either 1592U89 or CBV, with CBV-TP being the major phosphorylated species. We confirmed that CBV is phosphorylated by 5'-nucleotidase and that mycophenolic acid increased the formation of CBV-TP from CBV 75-fold. However, mycophenolic acid did not stimulate 1592U89 anabolism to CBV-TP. The adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) did not inhibit CBV-TP formation from CBV or 1592U89, whereas the adenylate deaminase inhibitor 2'-deoxycoformycin selectively inhibited 1592U89 anabolism to CBV-TP and reversed the antiviral activity of 1592U89. 1592U89-MP was not a substrate for adenylate deaminase but was a substrate for a distinct cytosolic deaminase that was inhibited by 2'-deoxycoformycin-5'-MP. Thus, 1592U89 is phosphorylated by adenosine phosphotransferase to 1592U89-MP, which is converted by a novel cytosolic enzyme to CBV-MP. CBV-MP is then further phosphorylated to CBV-TP by cellular kinases. This unique activation pathway enables 1592U89 to overcome the pharmacokinetic and toxicological deficiencies of CBV while maintaining potent and selective anti-HIV activity.

Asunto(s)

Fármacos Anti-VIH/metabolismo , Antivirales/metabolismo , Didesoxinucleósidos/metabolismo , Animales , Antígenos CD4/efectos de los fármacos , Antígenos CD4/metabolismo , Células Cultivadas , Cromatografía Líquida de Alta Presión , Desaminación , Humanos , Hígado/efectos de los fármacos , Hígado/metabolismo , Fosforilación , Ratas , Relación Estructura-Actividad

RESUMEN

DNA polymerase activity was assayed in hepatitis B virus (HBV) and core particles isolated from chronic producer lines. The particle-associated DNA polymerase activity, which was found to be limited to incorporation of only a few nucleotides, was inhibited by the 5'-triphosphates of nucleoside analogs. The 1-beta-L (1S,4R) and 1-beta-D (1R,4S) enantiomers of antiviral nucleoside analogs were compared for the ability to inhibit incorporation of natural nucleoside triphosphates into the viral DNA. Previously, both enantiomers of several analogs were found to be substrates for human immunodeficiency virus type 1 reverse transcriptase (HIV RT); the 1-beta-D enantiomers of some pairs were preferred as substrates. In contrast, the 1-beta-L enantiomers of all pairs tested were the more potent inhibitors of labeled substrate incorporation into hepatitis B virus DNA; the concentration required to inhibit the incorporation of the natural substrate by 50% was 6-fold to several hundred-fold lower than the concentration of the 1-beta-D enantiomer required for the same inhibitory effect. This preference for the 1-beta-L enantiomers was observed for both RNA-directed synthesis in core particles and DNA-directed synthesis in viral particles. The observed antiviral effect of the nucleoside analogs in cell culture seemed to be limited chiefly by their phosphorylation in cells.

Asunto(s)

Virus de la Hepatitis B/enzimología , Inhibidores de la Síntesis del Ácido Nucleico , Nucleótidos/farmacología , ADN Viral , ADN Polimerasa Dirigida por ADN/metabolismo , Nucleótidos de Desoxicitosina/metabolismo , Nucleótidos de Desoxiguanina/metabolismo , Emtricitabina/análogos & derivados , Virus de la Hepatitis B/genética , Humanos , Marcaje Isotópico , Moldes Genéticos , Nucleótidos de Timina/metabolismo , Zalcitabina/análogos & derivados , Zalcitabina/metabolismo

RESUMEN

5-Chloro-2',3'-dideoxy-3'-fluorouridine (935U83) is a selective anti-human immunodeficiency virus (HIV) agent. When tested in phytohemagglutinin-stimulated normal human peripheral blood lymphocytes against fresh clinical isolates of HIV type 1 (HIV-1) obtained from patients naive to AZT (3'-azido-3'-deoxythymidine [zidovudine]), 935U83 inhibited virus growth with an average 50% inhibitory concentration (IC50) of 1.8 microM; corresponding IC50s were 0.10 microM for FLT (3'-deoxy-3'-fluorothymidine) and 0.23, 0.49, and 0.03 microM for the approved agents AZT, ddI (2',3'-dideoxyinosine), and ddC (2',3'-dideoxycytosine), respectively. Importantly, 935U83 retained activity against HIV strains that were resistant to AZT, ddI, or ddC. Of additional interest, we were unable to generate virus which was resistant to 935U83 by passaging either HXB2 (AZT-sensitive) or RTMC (AZT-resistant) strains in the presence of high concentrations of 935U83. The anabolic profile of 935U83 was similar to that of AZT, and 935U83 triphosphate was a potent inhibitor of HIV-1 reverse transcriptase. Pharmacokinetic evaluation showed good oral bioavailability (86% in mice and 60% in monkeys) and less extensive metabolism to the glucuronide relative to AZT. 935U83 showed low toxicity. In an in vitro assay for toxicity to a human erythrocyte progenitor, erythroid burst-forming unit (BFU-E), the IC50 for 935U83 (> 400 microM) was more than 1,000-fold those of FLT (0.07 microM) and AZT (0.30 microM). Mild reversible reductions in erythrocytes and associated parameters were seen in mice dosed orally with 2,000 mg of 935U83 per kg per day for 1 and 6 months. In monkeys dosed orally with up to 700 mg/kg/day for 1 and 6 months, the only possible treatment-related finding was cataracts in 1 of 12 animals given the intermediate dose of 225 mg/kg/day. At the highest doses in mice and monkeys, maximal concentrations in plasma were more than 100-fold the anti-HIV IC50s against clinical isolates. This safety profile in animals compares very favorably with that of any of the anti-HIV drugs approved to date and has led us to begin evaluation of 935U83 in patients with HIV infection.

Asunto(s)

Antivirales/farmacología , Didesoxinucleósidos/farmacología , VIH-1/efectos de los fármacos , Animales , Antivirales/farmacocinética , Antivirales/toxicidad , Secuencia de Bases , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD4-Positivos/microbiología , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Ensayo de Unidades Formadoras de Colonias , ADN Mitocondrial/efectos de los fármacos , ADN Mitocondrial/metabolismo , ADN Viral/análisis , ADN Polimerasa Dirigida por ADN/metabolismo , Didesoxinucleósidos/farmacocinética , Didesoxinucleósidos/toxicidad , Femenino , Transcriptasa Inversa del VIH , Humanos , Técnicas In Vitro , Macaca fascicularis , Masculino , Ratones , Microsomas Hepáticos/metabolismo , Datos de Secuencia Molecular , Pruebas de Mutagenicidad , Nucleósidos/metabolismo , Fosforilación , Ratas , Inhibidores de la Transcriptasa Inversa

RESUMEN

A murine model was developed to investigate the in vivo activity of anti-hepatitis B virus (HBV) agents. Mice with subcutaneous tumors of HBV-producing 2.2.15 cells showed reductions in levels of HBV in serum and in intracellular levels of HBV when the mice were orally dosed with (-) cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine (FTC). No effects on tumor size or alpha-fetoprotein levels were observed. FTC can selectively inhibit HBV replication at nontoxic doses.

Asunto(s)

Antivirales/uso terapéutico , Hepatitis B/tratamiento farmacológico , Zalcitabina/análogos & derivados , Animales , Disponibilidad Biológica , Línea Celular , ADN Viral/biosíntesis , Emtricitabina/análogos & derivados , Hepatitis B/microbiología , Virus de la Hepatitis B/efectos de los fármacos , Humanos , Ratones , Reacción en Cadena de la Polimerasa , Replicación Viral/efectos de los fármacos , Zalcitabina/uso terapéutico , alfa-Fetoproteínas/metabolismo

RESUMEN

The varicella-zoster virus (VZV) thymidine kinase (TK) EC 2.7.2.21) catalyzes the phosphorylation of many anti-VZV nucleosides. Purified, bacterially expressed VZV TK was characterized with regard to N-terminal amino acid sequence, pI value, pH optimum, metal ion requirement, phosphate donor and acceptor specificity, and inhibition by dTTP. Initial velocities of thymidine phosphorylation with variable MgATP concentrations fit a two-site model with apparent Km values for MgATP of 0.10 and 900 microM. dTTP was a noncompetitive inhibitor of thymidine phosphorylation but was competitive with MgATP. Phosphate donor and acceptor specificities of the bacterially expressed enzyme were indistinguishable from those of VZV TK purified from infected cells. Detailed studies of the nucleoside specificity with the bacterially expressed enzyme showed that, for a given sugar moiety, thymine nucleosides were the most efficient substrates followed by nucleosides of cytosine, uracil, adenine, and with some exceptions, guanine. For a given pyrimidine or purine (except guanine), 2'-deoxyribonucleosides were the most efficient substrates, followed by arabinosides, ribonucleosides, 2',3'-dideoxyribonucleosides, and the acyclic moiety of acyclovir.

Asunto(s)

Herpesvirus Humano 3/enzimología , Timidina Quinasa/metabolismo , Adenosina Trifosfato/farmacología , Secuencia de Aminoácidos , Metabolismo de los Hidratos de Carbono , Carbohidratos/química , Escherichia coli/genética , Concentración de Iones de Hidrógeno , Punto Isoeléctrico , Metales , Compuestos Organofosforados/metabolismo , Fosforilación , Nucleósidos de Pirimidina/química , Nucleósidos de Pirimidina/metabolismo , Especificidad por Sustrato , Timidina Quinasa/antagonistas & inhibidores , Timidina Quinasa/genética

RESUMEN

During examination of the half-lives in cattle of a series of 5-substituted diaminobenzyl-pyrimidines, it was found that replacement of the phenyl ring of trimethoprim (TMP) by bicyclic structures, particularly a quinolyl group, led to increases in half-life. The presence of a dimethylamino group on the quinolyl ring of the compound baquiloprim (BQP) conferred a half-life of about 10 hours. In contrast to TMP (half-life about one hour), BQP was well absorbed from the gastrointestinal tract in all ages of cattle, plasma concentrations reaching a plateau on the day after dosing followed by a slow decline. BQP showed the same high broad spectrum antibacterial activity as TMP, with marked synergy with sulphonamides. Its differential binding of the dihydrofolate reductases of Escherichia coli and rat liver predicted a margin of safety similar to that of TMP. The results of efficacy studies in mice in comparison with TMP showed that the longer half-life of BQP was associated with greater efficacy, and therapeutic properties superior to those of TMP in cattle were therefore predicted for BQP.

Asunto(s)

Antibacterianos/farmacocinética , Bovinos/metabolismo , Antagonistas del Ácido Fólico/farmacocinética , Pirimidinas/farmacocinética , Administración Oral , Animales , Bacillus/efectos de los fármacos , Disponibilidad Biológica , Bovinos/microbiología , Escherichia coli/enzimología , Infecciones por Escherichia coli/prevención & control , Femenino , Semivida , Hígado/enzimología , Ratones , Ratones Endogámicos , Pruebas de Sensibilidad Microbiana/veterinaria , Pirimidinas/administración & dosificación , Pirimidinas/toxicidad , Ratas , Trimetoprim/toxicidad

RESUMEN

Carbovir (9-[4 alpha-(hydroxymethyl)cyclopent-2-ene-1 alpha-yl]guanine) (CBV) is a carbocyclic analogue of 2',3'-dideoxyguanosine that exhibits potent and selective in vitro activity against human immunodeficiency virus. Antiviral activity is associated with only the (-)-enantiomer. The transport characteristics of both (-)-CBV and (+)-CBV were investigated in human erythrocytes at 37 degrees C using a papaverine-stop assay. The influx of both enantiomers appeared saturable and was inhibited greater than 90% by a combination of adenine (a low Km permeant of the nucleobase carrier) and dilazep (a potent inhibitor of nucleoside transport). The influx of (-)-CBV and (+)-CBV proceeded primarily via the nucleobase carrier with Vmax (picomoles/second/5 microliters of cells)/Km (millimolar) values of 17/0.12 and 140/1.9, respectively. To a lesser extent, the influx of (-)-CBV and (+)-CBV also occurred via the nucleoside transporter. Although both compounds exhibited a similar low affinity for this latter carrier (Km approximately 2 mM), the Vmax for (-)-CBV influx was approximately 4-fold higher than the Vmax for (+)-CBV influx. We conclude that both CBV enantiomers enter human erythrocytes by two transporters that are enantiomerically selective.

Asunto(s)

Didesoxinucleósidos/metabolismo , Antivirales/metabolismo , Transporte Biológico , Células Cultivadas , Difusión , Membrana Eritrocítica/metabolismo , Humanos , Cinética , Estereoisomerismo

RESUMEN

Two enantiomers of carbovir, a carbocyclic analog of 2',3'-dideoxyguanosine, were compared with respect to their phosphorylation and the phosphorylation of their nucleotides by mammalian enzymes. 5'-Nucleotidase catalyzed the phosphorylation of (-)-carbovir, which is active against HIV (human immunodeficiency virus), but did not phosphorylate (+)-carbovir. (-)-Carbovir monophosphate was 7,000 times more efficient as a substrate for GMP kinase than was (+)-carbovir monophosphate. Pyruvate kinase, phosphoglycerate kinase, and creatine kinase phosphorylated both enantiomers of carbovir diphosphate at similar rates. Nucleoside-diphosphate kinase preferentially phosphorylated the (-)-enantiomer. Both enantiomers of carbovir triphosphate were substrates and alternative substrate inhibitors of HIV reverse transcriptase. Thus, the contrasting HIV-inhibitory activities of carbovir enantiomers were due to differential phosphorylation by cellular enzymes and not due to enantioselectivity of HIV reverse transcriptase.

Asunto(s)

Antivirales/metabolismo , Antivirales/farmacología , Didesoxinucleósidos/metabolismo , Didesoxinucleósidos/farmacología , VIH/efectos de los fármacos , Fosfotransferasas/metabolismo , Inhibidores de la Transcriptasa Inversa , Antivirales/química , Creatina Quinasa/metabolismo , Nucleótidos de Desoxiguanina/metabolismo , Nucleótidos de Desoxiguanina/farmacología , Didesoxinucleósidos/química , Guanilato-Quinasas , VIH/enzimología , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Nucleósido-Fosfato Quinasa/metabolismo , Fosfoenolpiruvato Carboxiquinasa (GTP)/metabolismo , Fosfoglicerato Quinasa/metabolismo , Fosforilación , Piruvato Quinasa/metabolismo , Estereoisomerismo , Moldes Genéticos

RESUMEN

Carbocyclic 2',3'-didehydro-2',3'-dideoxyguanosine (Carbovir: NSC 614846), a novel nucleoside analog, emerged as a potent and selective anti-HIV agent from a large screening program conducted by the National Cancer Institute and its contractors. Its hydrolytic stability and its ability to inhibit the infectivity and replication of HIV in T-cells at concentrations of approximately 200- to 400-fold below toxic concentrations make carbovir a top-priority candidate for development as a potential antiretroviral agent in the treatment of AIDS patients.

Asunto(s)

Didesoxinucleósidos/farmacología , VIH/efectos de los fármacos , Síndrome de Inmunodeficiencia Adquirida/tratamiento farmacológico , Antivirales , Efecto Citopatogénico Viral/efectos de los fármacos , VIH/fisiología , Estructura Molecular , Relación Estructura-Actividad , Replicación Viral/efectos de los fármacos , Zalcitabina , Zidovudina/farmacología

RESUMEN

3-(4-Amino)phenethyl-1-propyl-8-cyclopentylxanthine (BW-A844U) has been synthesized and shown to bind with high affinity to adenosine A1 receptors of bovine brain membranes (KD = 0.23 nM). This compound is highly selective for A1 receptors; the KI for binding to A2 receptors of human platelet membranes is 2.0 microM (A2/A1 ratio = 8700). Radioiodination of the 3-aminophenethyl group resulted in 125I-BW-A844U, a radioligand that retains high affinity for A1 receptors in bovine brain membranes (KD = 0.14 nM) and to 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate-solubilized receptors (KD = 0.34 nM). Specific binding of 125I-BW-A844U represented greater than 90% of the total binding at the KD. From the association constant (K1 = 5.0 X 10(8) M-1min-1) and the dissociation constant (K-1 = 0.064 min-1), the kinetic KD (K-1/K1) in membranes was calculated to be 0.13 nM. NaCl (1 M) had little effect on the binding affinity of 125I-BW-A844U, in contrast to the large effect of salt on the binding affinity of acidic antagonist radioligands. 8-Sulfophenyltheophylline inhibited radioligand binding with a Hill coefficient of 1.0, indicative of a single affinity binding state for the antagonist. By comparison, two distinct agonist affinity states of A1 receptors for the agonist (R)-phenylisopropyladenosine could be resolved, a high affinity state (62%, KH = 74 pM) and a low affinity state (KL = 3.83 nM). The addition of 0.1 mM guanylylimidodiphosphate converted all receptors to the low affinity state. Addition of NaCl (0.5 M) decreased the fraction of receptors in the high affinity state and increased both KH and KL, suggesting that NaCl alters coupling of receptors to G proteins and influences the conformation of the receptor polypeptide, whether or not the receptor is coupled to a G protein. Conversion of the arylamine on the 3-position of 125I-BW-A844U to an aryl azide resulted in a photoaffinity label, 125I-azido-BW-A844U. Upon photoactivation, the photoaffinity label was specifically photoincorporated into the 34,000-dalton polypeptide of the adenosine A1 receptor.

Asunto(s)

Adenosina/antagonistas & inhibidores , Marcadores de Afinidad/metabolismo , Azidas/metabolismo , Receptores Purinérgicos/metabolismo , Xantinas/metabolismo , Animales , Unión Competitiva , Encéfalo/metabolismo , Bovinos , Guanilil Imidodifosfato/farmacología , Técnicas In Vitro , Radioisótopos de Yodo , Cinética , Ligandos , Receptores Purinérgicos/efectos de los fármacos , Cloruro de Sodio/farmacología

RESUMEN

A series of 8-phenylxanthine derivatives has been synthesized with oxyacetic acid on the para phenyl position to increase aqueous solubility and minimize nonspecific binding and iodinatable groups on the 1- or 3-position of the xanthine ring. The structure-activity relationship for binding of these compounds to A1 adenosine receptors of bovine and rat brain and A2 receptors of human platelets was examined. The addition of arylamine or photosensitive aryl azide groups to the 3-position of xanthine had little effect on A1 binding affinity with or without iodination, whereas substitutions at the 1-position caused greatly reduced A1 binding affinity. The addition of an aminobenzyl group to the 3-position of the xanthine had little effect on A2 binding affinity, but 3-aminophenethyl substitution decreased A2 binding affinity. Two acidic 3-(arylamino)-8-phenylxanthine derivatives were labeled with 125I and evaluated as A1 receptor radioligands. The new radioligands bound to A1 receptors with KD values of 1-1.25 nM. Specific binding represented over 80% of total binding. High concentrations of NaCl or other salts increased the binding affinity of acidic but not neutral antagonists, suggesting that interactions between ionized xanthines and receptors may be affected significantly by changes in ionic strength. On the basis of binding studies with these antagonists and isotope dilution with the agonist [125I]N6-(4-amino-3-iodobenzyl)adenosine, multiple agonist affinity states of A1 receptors have been identified.

Asunto(s)

Adenosina/análogos & derivados , Marcadores de Afinidad/síntesis química , Yodobencenos/metabolismo , Receptores Purinérgicos/metabolismo , Xantinas/síntesis química , Adenosina/metabolismo , Adenosina/farmacología , Adenosina-5'-(N-etilcarboxamida) , Adenilil Ciclasas/metabolismo , Marcadores de Afinidad/metabolismo , Algoritmos , Animales , Unión Competitiva , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Bovinos , Humanos , Radioisótopos de Yodo , Marcaje Isotópico , Cinética , Ligandos , Membranas/metabolismo , Ratas , Ratas Endogámicas , Cloruro de Sodio/farmacología , Relación Estructura-Actividad , Teofilina/análogos & derivados , Teofilina/metabolismo , Xantinas/metabolismo

RESUMEN

We have derivatized a series of 125I-labeled 8-phenylxanthines with photoactive aryl azide groups on the 1- or 3-position of the xanthine ring. A 3-azidophenethyl derivative was found to be optimal for use as an antagonist photoaffinity label for adenosine A1 receptors. Following photoactivation, radioactivity was covalently and specifically incorporated into a 34,000-dalton and, to a lesser extent, into a 24,000-dalton polypeptide of rat brain membranes. Photoincorporation into both polypeptides was competitively inhibited by adenosine analogues with a potency order typical of adenosine A1 receptors, but the 24,000-dalton polypeptide bound both agonists and antagonists with lower affinity than the 34,000-dalton polypeptide. Specific photolabeling of receptors in brain membranes of rat, guinea pig, dog, and cow did not show any variation in the 34,000-dalton adenosine receptor binding subunit. The adenosine agonist photoaffinity label [125I]N6-(4-azido-3-iodobenzyl)adenosine also specifically photolabeled the 34,000-dalton polypeptide, but photoincorporation of the agonist was less efficient than the antagonist and, unlike the antagonist, was greatly reduced by guanosine 5'-(beta,gamma-imidotriphosphate). The results indicate that the antagonist photoaffinity label may be more useful than agonists particularly for labeling uncoupled receptors.

Asunto(s)

Marcadores de Afinidad/metabolismo , Azidas/metabolismo , Purinas/metabolismo , Receptores Purinérgicos/metabolismo , Marcadores de Afinidad/síntesis química , Animales , Azidas/síntesis química , Encéfalo/metabolismo , Bovinos , Cromatografía Líquida de Alta Presión , Perros , Cobayas , Radioisótopos de Yodo , Marcaje Isotópico , Membranas/metabolismo , Peso Molecular , Fotoquímica , Purinas/síntesis química , Ratas , Relación Estructura-Actividad

RESUMEN

The carbocyclic analogue of puromycin was prepared by the coupling of N-(benzyloxycarbonyl)-p-methoxy-L-phenylalanine to the racemic aminonucleoside (+/-)-9-[3 beta-amino-2 beta-hydroxy-4 alpha-(hydroxymethyl)cyclopent-1 alpha-yl]-6-(dimethylamino)purine, followed by separation of the diastereomers and subsequent removal of the Cbz blocking group. Kinetic studies indicate that carbocyclic puromycin is an excellent substrate for the peptidyltransferase reaction with both prokaryotic and eukaryotic ribosomes. A comparison of carbocyclic puromycin with previously synthesized analogues indicate that the furanosyl ring oxygen and the hydroxymethyl group of puromycin do not contribute to ribosomal binding, but both moieties contribute to the rate of product formation from the enzyme-substrate complex. Carbocyclic puromycin was equal to puromycin when evaluated for cytotoxicity using P-388 mouse lymphoid leukemia cells in culture.

Asunto(s)

Biosíntesis de Proteínas , Puromicina/análogos & derivados , Animales , Leucemia P388/patología , Ratones , Puromicina/síntesis química , Puromicina/farmacología , Ribosomas/metabolismo , Relación Estructura-Actividad

RESUMEN

(+/-)-4 alpha-Amino-2 alpha,3 beta-dihydroxy-1 alpha-cyclopentanemethanol (6), the carbocyclic analogue of xylofuranosylamine, was synthesized from the previously reported 4 alpha-acetamido-2 alpha,3 alpha-epoxycyclopentane-1 alpha-methanol. Amine 6 was converted to (+/-)-4 alpha-[(5-amino-6-chloro-4-pyrimidinyl)amino]-2 alpha,3 beta-dihydroxy-1 alpha-cyclopentanemethanol (7) by condensation with 5-amino-4,6-dichloropyrimidine. From 7, the carbocyclic analogues of xylofuranosyladenine and xylofuranosyl-8-azaadenine were prepared. In contrast to 9-beta-D-xylofuranosyladenine and its 8-aza analogue, the corresponding carbocyclic nucleosides were resistant to deamination by adenosine deaminase. The carbocyclic 8-aza derivative 10 exhibited significant in vivo antitumor activity which varied according to treatment schedule.

Asunto(s)

Antibióticos Antineoplásicos/síntesis química , Nucleósidos de Purina/síntesis química , Adenosina Desaminasa/metabolismo , Animales , Fenómenos Químicos , Química , Leucemia P388/tratamiento farmacológico , Espectroscopía de Resonancia Magnética , Ratones , Nucleósidos de Purina/toxicidad , Espectrofotometría Infrarroja , Relación Estructura-Actividad

RESUMEN

The relative therapeutic effects of vidarabine (9-beta-D-arabinofuranosyladenine), cyclaradine (the adenosine deaminase-resistant carbocyclic analog of vidarabine), and cyclaradine-5'-methoxyacetate in the parenteral treatment of systemic herpes simplex virus type 1 infections in Swiss mice were determined. Among control mice inoculated intraperitoneally with virus, a mortality rate of 95% was observed. The intraperitoneal administration of nontoxic doses of vidarabine (125 to 250 mg/kg per day) or cyclaradine (113 to 450 mg/kg per day), by daily injections for 7 days beginning 4 h after virus inoculation, reduced mortality to 0 to 10%. Among control animals inoculated intracerebrally with 32 50% lethal doses of virus, 100% mortality was observed, with a mean survival time of 4.6 days. Treatment with either drug at equimolar dose levels ranging from ca. 32 to 750 mg/kg per day produced significant (P less than 0.0005), dose-dependent increases in the mean survival time of animals dying of herpesvirus encephalitis. Mice inoculated intracerebrally with 10 50% lethal doses of virus exhibited 97% mortality and a mean survival time of 5.5 to 6.4 days. Treatment with vidarabine, cyclaradine, or cyclaradine-5'-methoxyacetate significantly increased the mean survival time of dying animals and, at doses ranging from 250 to 750 mg/kg per day, produced significant increases in survival. The three drugs displayed equivalent antiviral efficacy in vivo. Drug toxicity (measured by weight loss) was not detected in mice treated with cyclaradine or cyclaradine-5'-methoxyacetate at 750 mg/kg per day, whereas severe toxicity (weight loss of greater than or equal to 3 g) was observed in mice treated with vidarabine at an equivalent dose level. Thus, cyclaradine or its 5'-methoxyacetic acid ester may possess some advantage over vidarabine in the treatment of severe herpesvirus infections and should therefore be considered for clinical trials in humans.

Asunto(s)

Antivirales/uso terapéutico , Encefalitis/tratamiento farmacológico , Herpes Simple/tratamiento farmacológico , Vidarabina/análogos & derivados , Vidarabina/uso terapéutico , Animales , Evaluación Preclínica de Medicamentos , Femenino , Ratones

RESUMEN

Carbocyclic arabinofuranosyladenine (cyclaradine), a novel nucleoside analog with such desired features as hydrolytic and enzymatic stability, adenosine deaminase resistance, and low systemic toxicity, inhibited the replication of herpes simplex virus types 1 and 2. The 5'-methoxyacetate prodrug form exhibited significant efficacy in the topical treatment of genital infections by herpes simplex virus type 2.

Asunto(s)

Herpes Genital/tratamiento farmacológico , Vidarabina/análogos & derivados , Aciclovir/uso terapéutico , Animales , Modelos Animales de Enfermedad , Femenino , Cobayas , Masculino , Relación Estructura-Actividad , Vidarabina/uso terapéutico