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J Balzarini

Publications and source records attributed to J Balzarini.

At least 415 records · Page 23Linked to original sources
PubMed1989

Synthesis, DNA binding, and biological evaluation of synthetic precursors and novel analogues of netropsin.

A series of oligopeptides have been synthesized that are structurally related to the natural agent netropsin. The binding constants to double-stranded polynucleotides as well as the cytostatic activity against both murine human tumor cell lines and the in vitro activity against a range of DNA and RNA viruses have been determined for these novel compounds and some of their synthetic precursors. 1-Methyl-5-nitropyrrole-2-carboxylic acid methyl ester (4), N-[[1-methyl-4-(1-methyl-4-nitropyrrole-2-carboxamido)pyrrol-2- yl]carbonyl]-L-alanine tert-butyl ester (28), and N-[[1-methyl-4-(1-methyl-4-nitropyrrole-2-carboxamido)pyrrol-2- yl]carbonyl]-L-alanyl-L-alanine tert-butyl ester (29) showed modest inhibitory effect on tumor cell proliferation (CD50 = 26-85 micrograms/mL). Of all the compounds that were evaluated, 28 proved the most potent antiviral agent. It was inhibitory to parainfluenza-3 virus and Coxsackie virus B4 in Vero cells at a concentration of 20 micrograms/mL.

Animals↗
PubMed1989

Synthesis and antiviral activity of 3'-C-cyano-3'-deoxynucleosides.

A series of 3'-C-cyano-3'-deoxynucleosides have been synthesized and evaluated as antiviral agents. Reaction of 2',5'-bis-O-(tert-butyldimethylsilyl)-beta-D-erythro-pentofuranos- 3'-ulosyl derivatives of uracil, 4-N-acetylcytosine, and adenine with sodium cyanide gave a mixture of epimeric cyanohydrins, which after 3'-deoxygenation yielded the corresponding 3'-C-cyano-3'-deoxy-beta-D-xylo-pentofuranosyl derivatives 10. These compounds were epimerized to the corresponding beta-D-ribo-pentofuranosyl derivatives 11. Desilylation of 10 and 11 gave the deprotected 3'-C-cyano-3'-deoxy-beta-D-xylo- and -ribo-pentofuranosyl nucleosides. These derivatives of uridine, cytidine, and adenine, as well as the 3'-C-cyano-3'-deoxy-beta-D-xylo- and -ribo-pentofuranosyl, 3'-C-cyano-2',3'-dideoxy-beta-D-threo- and -erythro-pentofuranosyl, and 3'-C-cyano-2',3'-dideoxy-beta-D-glycero-pent-2'-enofuranosyl derivatives of thymine, were evaluated for their antiviral activity. None of the compounds proved active against the replication of retroviruses (human immunodeficiency virus, murine sarcoma virus) at concentrations that were not toxic to the host cells. However, the 3'-C-cyano-3'-deoxy-beta-D-xylo- (12e) and -ribo-pentofuranosyl (13e) derivatives of adenine showed activity against some DNA (i.e., vaccinia) and RNA (i.e., Sindbis, Semliki forest) viruses at concentrations well below the cytotoxicity threshold.

Antiviral Agents↗
PubMed1989

3'-Fluoro-2',3'-dideoxy-5-chlorouridine: most selective anti-HIV-1 agent among a series of new 2'- and 3'-fluorinated 2',3'-dideoxynucleoside analogues.

A series of 2'- and 3'-fluorinated 2',3'-dideoxynucleosides and 3'-azido-2',3'-dideoxynucleosides were synthesized and evaluated for their inhibitory activity against human immunodeficiency virus-1 (HIV-1) replication in MT-4 cells. Neither conversion of 3'-fluoro- or 3'-azido-2',3'-dideoxyadenosine to the corresponding inosine derivatives nor 8-bromination of 2',3'-dideoxyadenosine resulted in increased anti-HIV-1 activity. Nor did introduction of a 2'-fluorine in the erythro or threo configuration lead to improved anti-HIV-1 activity of the parent 2',3'-dideoxynucleosides. 1-(2-Fluoro-2,3-dideoxy-beta-D-threo-pentofuranosyl)cytosine and 1-(2-fluoro-2,3-dideoxy-beta-D-erythropentofuranosyl)thymine were only marginally active. However, 3'-fluoro-2',3'-dideoxyuridine (FddUrd) proved to be potent and a relatively nontoxic inhibitor of HIV-1. 5-Halogenated derivatives of FddUrd were prepared in attempts to further increase its anti-HIV potency and selectivity. Of these 5-halogenated derivatives, 3'-fluoro-2',3'-dideoxy-5-chlorouridine emerged as the most selective inhibitor of HIV-1 replication. Its selectivity index was comparable to that of azidothymidine when evaluated under the same conditions.

Antiviral Agents↗
PubMed1989

Nucleic acid related compounds. 57. Synthesis, x-ray crystal structure, lipophilic partition properties, and antiretroviral activities of anomeric 3'-azido-2',3'-dideoxy-2,6-diaminopurine ribosides.

Trimethylsilyl triflate-catalyzed transfer glycosylation of 2,6-diamino-9-(3-azido-2,3-dideoxy-alpha- and -beta-D-erythro-pentofuranosyl)purines (3 and 4) in low yields. Selective 2'-O-tosylation of 2,6-diamino-9-(beta-D-ribofuranosyl)purine (2,6-diaminopurine riboside, DAPR, 5) followed by our lithium triethylborohydride promoted 1,2-hydride rearrangement gave 2,6-diamino-9-(2-deoxy-beta-D-threo-pentofuranosyl)purine (7). Tritylation of 7 followed by mesylation at O3', deprotection, and displacement of the 3'-mesylate with azide provided a stereodefined synthesis of 2,6-diamino-9-(3-azido-2, 3-dideoxy-beta-D-erythro-pentofuranosyl)purine (AzddDAPR, 4). X-ray crystallographic analysis of 4 showed two orientations of the azido group, but consistent conformational features in the remainder of the molecule. In contrast, two independent conformations have been found for AZT. The azido function confers enhanced lipophilicity, which could be expected to contribute significantly to nonselective transport across membranes. A large difference in the octanol/water partition coefficients of the alpha (3) and beta (4) anomers wes found. The beta anomer (4) exerts potent inhibition of HIV-induced cytopathogenicity in human MT-4 cells (ED50: 0.3 microM). This concentration is an order of magnitude lower than that required for ddDAPR, AzddAdo, and AzddGuo. Potent inhibition of Moloney sarcoma virus induced transformation of murine C3H cells by AzddDAPR (4) was also observed. The alpha anomer (3) had no observed antiviral activity.

Animals↗
PubMed1989

Synthesis and antiviral activity of the enantiomeric forms of carba-5-iodo-2'-deoxyuridine and carba-(E)-5-(2-bromovinyl)-2'-deoxyuridine.

Both enantiomers of the carbocyclic analogues of 5-iodo-2'-deoxyuridine (14 and ent-14) and of (E)-5-(2-bromo-vinyl)-2'-deoxyuridine (16 and ent-16) were synthesized by using (+)- or (-)-endo-norborn-5-en-2-yl acetate or butyrate, respectively, as starting materials. Against herpes simplex virus type 1 (+)-C-BVDU (16) was only slightly less active than BVDU itself, whereas (-)-C-BVDU (ent-16) proved to be 10-400-fold less effective, depending on the strain investigated. Against HSV-2 both (+)- and (-)-C-BVDU as well as (+)- and (-)-C-IDU showed minor activity. All carbocyclic analogues were inactive against TK-HSV-1 strains, pointing to the prerequisite of phosphorylation (activation) by the viral thymidine kinase (TK).

Antiviral Agents↗
PubMed1989

Novel linked antiviral and antitumor agents related to netropsin and distamycin: synthesis and biological evaluation.

A group of oligopeptides have been synthesized which are structurally related to the natural antiviral antitumor antibiotics netropsin and distamycin bearing two such moieties linked by polymethylene bridges. Cytostatic activity against both human and murine tumor cell lines and their in vitro activity against a range of viruses are reported. Enhanced antiviral activity was obtained against vaccinia virus. As a result of the introduction of the polymethylene linkers [( CH2)n, with n = 1, 2, and 6-8], both the antitumor and antivaccinia virus activity was markedly enhanced, relative to that of the parent compounds netropsin and distamycin. The biological activity of these agents is discussed both in terms of their structural differences and in relation to their minor groove binding to duplex DNA.

Animals↗
PubMed1989

Marked in vivo antiretrovirus activity of 9-(2-phosphonylmethoxyethyl)adenine, a selective anti-human immunodeficiency virus agent.

9-(2-Phosphonylmethoxyethyl)adenine (PMEA) is a potent and selective inhibitor of the replication of human immunodeficiency virus (HIV) in vitro in human T-lymphocyte MT-4, H9, and ATH8 cells. PMEA also inhibits Moloney murine sarcoma virus (Mo-MSV)-induced transformation of murine C3H embryo fibroblasts. Moreover, PMEA causes a dose-dependent suppression of tumor formation and associated mortality in mice inoculated with Mo-MSV. At a dose of 50 or 20 mg/kg per day PMEA effected a 90-100% protection of the mice against Mo-MSV-induced tumor formation and mortality. Even with a PMEA dose as low as 1 to 5 mg/kg per day, tumor formation was significantly delayed and the survival rate was significantly enhanced. In parallel experiments, azidothymidine exhibited a comparable inhibitory effect on Mo-MSV-induced tumor formation and associated death only at a 25-fold higher dose than PMEA. Because PMEA has stronger in vivo antiretrovirus potency and selectivity than azidothymidine and various other compounds currently being subjected to clinical trials, PMEA studies should be pursued to assess the potential of this compound in the treatment of acquired immunodeficiency syndrome (AIDS) and other retrovirus infections in humans.

Adenine↗
PubMed1989

9-(2-Phosphonylmethoxyethyl)adenine in the treatment of murine acquired immunodeficiency disease and opportunistic herpes simplex virus infections.

The murine model of acquired immunodeficiency disease was used to evaluate both the antiretroviral and antiherpetic activities of the acyclic nucleotide analog 9-(2-phosphonylmethoxyethyl)adenine (PMEA). The antiretroviral activity of PMEA was compared with that of azidothymidine (AZT) in mice receiving the drug either immediately after infection or at late times in disease progression. Both AZT (oral, 30 mg/kg) and PMEA (parenteral, 25 and 5 mg/kg) were effective in slowing the development of disease when administered daily beginning on the day of infection. In contrast, neither drug alone was effective in modifying disease outcome when administered several weeks after viral infection. Human recombinant alpha interferon (rhuIFN alpha-B/D at 5 x 10(7) U/kg) was also ineffective when administered late in the course of disease. However, when administered in combination, both alpha interferon and PMEA (25 mg/kg) were able to suppress disease progression even when treatment was initiated as late as 3 weeks postinfection. Mice that were immunocompromised due to LP-BM5 virus infection were highly susceptible to acute (lethal) infection with herpes simplex virus type 1, whereas their immunocompetent littermates were not. PMEA was as effective as acyclovir in the treatment of opportunistic herpes simplex virus type 1 infections in LP-BM5 virus-infected mice. Thus, like AZT, PMEA was effective against retrovirus infection, and, like acyclovir, PMEA was effective against herpes simplex virus type 1 infection. This gives PMEA the unique potential of being useful in the treatment of opportunistic herpes simplex virus infections as well as the underlying retroviral disease.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Broad-spectrum antiviral activities of neplanocin A, 3-deazaneplanocin A, and their 5'-nor derivatives.

The neplanocin A analogs, 3-deazaneplanocin A, 9-(trans-2',trans-3'-dihydroxycyclopent-4'-enyl)adenine (DHCA), and 9-(trans-2',trans-3'-dihydroxycyclopent-4'-enyl)-3-deazaadenine (DHCDA), all potent inhibitors of S-adenosylhomocysteine (AdoHcy) hydrolase, were studied for their broad-spectrum antiviral potential. 3-Deazaneplanocin A, DHCA, and DHCDA proved specifically effective against vesicular stomatitis virus, vaccinia virus, parainfluenza virus, reovirus, and rotavirus. Their selectivity was greater than that of neplanocin A, particularly against vesicular stomatitis virus and rotavirus. As could be expected from adenosine analogs that are directly targeted at AdoHcy hydrolase, 3-deazaneplanocin A, DHCA, and DHCDA were fully active in adenosine kinase-deficient cells, implying that their activity did not depend on phosphorylation by adenosine kinase. None of the AdoHcy hydrolase inhibitors showed selective activity against human immunodeficiency virus (type 1). 3-Deazaneplanocin A at a dose of 0.5 mg/kg per day conferred marked protection against a lethal infection of newborn mice with vesicular stomatitis virus.

Adenosine↗
PubMed1989

Differential inhibitory effects of several pyrimidine 2',3'-dideoxynucleoside 5'-triphosphates on the activities of reverse transcriptase and various cellular DNA polymerases.

Several analogues of 2',3'-dideoxythymidine 5'-triphosphate [i.e., 3'-azido-2', 3'-dideoxythymidine 5'-triphosphate(Azdd TTP), 2',3'-didehydro-2',3'-dideoxythymidine 5'-triphosphate (ddeTTP), alpha, beta-methylene 3'-azido-2',3'-dideoxythymidine 5'-diphosphate, alpha, beta-methylene 3'-azido-2',3'-dideoxythymidine 5'-triphosphate, and beta, gamma-methylene 3'-azido-2',3'-dideoxythymidine 5'-triphosphate] and 2',3'-didehydro-2',3'-dideoxycytidine 5'-triphosphate (ddeCTP) have been evaluated for their inhibitory effects on murine retroviral reverse transcriptase and various other DNA polymerases, including DNA polymerases alpha, beta, and gamma, terminal deoxynucleotidyl transferase, and DNA polymerase I. None of the compounds inhibited the activity of DNA polymerase alpha under the reaction conditions employed. When Mg2+ was replaced by Mn2+, however, DNA polymerase alpha was strongly inhibited only by ddeTTP. DNA polymerase beta activity was inhibited only by ddeTTP and ddeCTP. All the compounds, except for ddeCTP, inhibited DNA polymerase gamma activity, ddeTTP being a particularly strong inhibitor of gamma-polymerase (Ki = 3.5 nM). Terminal deoxynucleotidyl transferase was only slightly inhibited by any of the compounds. AzddTTP was a potent inhibitor of reverse transcriptase (Ki = 42 nM), but it also inhibited the activities of DNA polymerase gamma and DNA polymerase I.

Antiviral Agents↗
PubMed1989

5-Halogeno-3'-fluoro-2',3'-dideoxyuridines as inhibitors of human immunodeficiency virus (HIV): potent and selective anti-HIV activity of 3'-fluoro-2',3'-dideoxy-5-chlorouridine.

The novel 5-chloro-, 5-bromo-, and 5-iodo-derivatives of 3'-fluoro-2',3'-dideoxyuridine (FddUrd), designated FddCIUrd, FddBrUrd, and FddIUrd, respectively, have been synthesized and evaluated for their antiretrovirus activity against human immunodeficiency virus (HIV) and murine Moloney sarcoma virus. All three 5-halogeno-FddUrd analogues inhibited HIV-1 replication in MT4 cells with an effective dose (ED50) of about 0.2-0.4 microM. However, FddCIUrd was markedly more selective in its anti-HIV-1 activity than FddBrUrd or FddIUrd. The selectivity index of FddCIUrd was similar to that of 3'-azido-2',3'-dideoxythymidine (AZT) when evaluated in parallel (1408 and 1603, respectively). The FddUrd derivatives also had a marked inhibitory effect on HIV-2 replication in MT4 cells and HIV-1 induced antigen expression in HUT-78 cells. However, neither FddUrd nor its 5-halogeno derivatives were inhibitory to Moloney sarcoma virus-induced transformation of murine C3H cells. The anti-HIV-1 activity of FddUrd, FddCIUrd, FddBrUrd, and FddIUrd was reversed by the addition of thymidine and 2'-deoxycytidine. The 5-halogeno-FddUrd analogues had a markedly higher affinity for MT4 thymidine kinase than FddUrd (Ki/Km, 4.0-4.7, as compared with 302 for FddUrd).

Antiviral Agents↗
PubMed1988

A highly reliable, sensitive, flow cytometric/fluorometric assay for the evaluation of the anti-HIV activity of antiviral compounds in MT-4 cells.

Infection of human T4 lymphocyte MT-4 cells with human immunodeficiency virus (HIV) results in cell death 4-5 days after infection. We have now developed a highly sensitive and rapid procedure for estimating the cytopathic effect of HIV in MT-4 cells. This method is based on fluorometric as well as flow cytometric evaluation of HIV-infected MT-4 cultures. By the use of fluorescein diacetate (FDA), a non-fluorescent diacetyl fluorescein ester that becomes fluorescent upon hydrolysis by esterases present in the cytoplasm of viable cells, as few as 100-200 viable MT-4 cells can be accurately determined. Applying this new method to HIV-infected MT-4 cell cultures treated with differing concentrations of the potent anti-HIV agent azidothymidine (AZT), we obtained a virus-inhibitory dose-response comparable to those obtained by the conventional (labour-intensive and time-consuming) methods. The FDA-based cell viability assay appears particularly suited for the rapid, reliable and sensitive evaluation of potential anti-AIDS agents in cell culture.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Differential inhibition of various deoxyribonucleic acid polymerases by Evans blue and aurintricarboxylic acid.

The inhibitory effects of two anionic compounds, Evans blue and aurintricarboxylic acid (ATA), on various kinds of polynucleotide-synthesizing enzymes were examined. Under the assay conditions, optimized for each enzyme species, both these compounds strongly inhibited the activities of the purified human DNA polymerases alpha, beta, gamma, and DNA primase as well as those of DNA polymerase I and RNA polymerase from Escherichia coli and Rauscher leukemia virus reverse transcriptase. ATA was particularly effective in inhibiting retroviral reverse transcriptase and cellular DNA polymerase alpha. Evans blue, which is a structural analogue of suramin, exerted its inhibitory action largely by competing with the template.primer for the same binding site of the enzyme. On the other hand, ATA inhibited most, if not all, of these enzyme activities noncompetitively with respect to either the template.primers or nucleoside 5'-triphosphate substrates. The inhibition constants for ATA were, in general, smaller than those for Evans blue.

Animals↗
PubMed1988

Fuchsin acid selectively inhibits human immunodeficiency virus (HIV) replication in vitro.

Fuchsin acid, an anionic dye, is a selective inhibitor of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) in vitro. Its 50% effective dose for inhibition of HIV-1-induced cytopathogenicity in MT-4 cells and HIV-1 antigen expression in HUT-78 cells is 42 and 16 microM, respectively. These values are comparable to those of suramin, the first compound shown to be a selective inhibitor of HIV-1. However, fuchsin acid is less cytotoxic than suramin. The selectivity index of fuchsin acid, based on the ratio of the 50% cytotoxic dose to the 50% effective dose, is greater than 74 in MT-4 cells and greater than 39 in HUT-78 cells. Fuchsin acid is a much weaker inhibitor of HIV-1 reverse transcriptase than are suramin and aurintricarboxylic acid. Fuchsin acid does not interfere with the adsorption of HIV-1 particles to MT-4 cells even at concentrations that completely block HIV-1 replication in MT-4 cells. The mechanism of action of fuchsin acid remains subject of further study.

Animals↗
PubMed1988

Anti-retrovirus activity of 3'-fluoro- and 3'-azido-substituted pyrimidine 2',3'-dideoxynucleoside analogues.

The 3'-fluoro-and 3'-azido-substituted derivatives of 2',3'-dideoxythymidine (ddThd), 2',3'-dideoxyuridine (ddUrd), 2',3'-dideoxy-5-ethyluridine (ddEtUrd) and 2',3'-dideoxycytidine (ddCyd) have been synthesized and evaluated for their anti-retrovirus activity [against human immunodeficiency virus (HIV) and murine Moloney sarcoma virus (MSV)]. Based on their 50% effective doses the most potent inhibitors of HIV replication in human MT4 lymphocytes were: FddThd (0.001 microM), AzddThd (0.004 microM), FddUrd (0.04 microM) and AzddUrd (0.36 microM). Their selectivity indexes were 197, 5000, 500 and 677, respectively. In contrast, none of the 3'-substituted ddEtUrd derivatives had a marked antiviral effect. The 2',3'-dideoxynucleoside analogues showed poor, if any, substrate affinity for (bacterial) dThd phosphorylase. AzddThd and FddThd inhibited human dThd kinase to a much greater extent (Ki/Km: 0.66 and 3.4, respectively) than did AzddUrd or FddUrd (Ki/Km: 71 and 171, respectively). The Ki/Km values of FddCyd and AzddCyd for human dCyd kinase were about 60. Although phosphorylation is a prerequisite for the anti-retrovirus activity of the 2',3'-dideoxynucleoside derivatives, there is no close correlation between the anti-retrovirus potency of the 3'-fluoro- and 3'-azido-substituted ddUrd, ddThd, ddEtUrd and ddCyd derivatives and their affinity for dThd kinase or dCyd kinase.

Animals↗
PubMed1988

AIDS dementia: synthesis and properties of a derivative of 3'-azido-3'-deoxythymidine (AZT) that may become 'locked' in the central nervous system.

In an attempt to provide a derivative of 3'-azido-3'-deoxythymidine (AZT) which might be sequestered in the central nervous system and release AZT, the dihydropyridine ester 5'-(1,4-dihydro-1-methyl-3-pyridinylcarbonyl)-3'-deoxythymidine, was synthesized in a three step sequence. This material showed potent anti-HIV-1 activity in MT-4 cells most probably by hydrolysis to the parent nucleoside, AZT. This dihydropyridine derivative of AZT could be easily oxidized to a positively charged pyridinium derivative of AZT in rat brain cytosol. In turn the pyridinium form could be hydrolyzed, non-enzymatically, to AZT.

Acquired Immunodeficiency Syndrome↗