pyrazofurin and carbodine

The detection of lactate dehydrogenase (LDH) can be used to evaluate efficiently anti-influenza A virus agents. LDH levels in the virus-infected Madin-Darby canine kidney cell cultures were significantly higher than in controls, were in proportion to the degree of virus infection, and corresponded to a decrease in mitochondrial dehydrogenase activity as assayed using a tetrazolium colorimetric assay (MTT method). The EC50 value and cytotoxicity of ribavirin, 3-deazaguanine, pyrazofurin, and carbodine against influenza A virus as measured by the LDH detection method was equivalent to that derived by the MTT method.

Topics: Amides; Animals; Antiviral Agents; Cell Line; Colorimetry; Coloring Agents; Cytidine; Dogs; Guanine; Influenza A virus; L-Lactate Dehydrogenase; Pyrazoles; Ribavirin; Ribonucleosides; Ribose; Tetrazolium Salts; Thiazoles

A rapid and sensitive method was developed for screening potential antiviral agents against orthomyxo- and paramyxoviruses, using the MTT method with cell culture suspensions. The cell lines used for the assay were as follows: MDCK cells for the influenza A virus (Fluv. A), HeLa cells for the respiratory syncytial virus (RSV), and Vero cells for the measles virus (MSV). Test compounds were diluted and plated in 96-well round-bottomed microtiter plates. Trypsinized cell suspensions and viruses were added to each well, the plates were then centrifuged (700 x g, 5 min, room temperature), and incubated for several days. The MTT assay was carried out after the degeneration of virus-infected cells became evident. The optical density (OD) of formazan was determined using a computer-controlled microplate reader. With this assay system, the EC50 values of Ribavirin (used as the reference compound) were 3.7 micrograms/ml for Fluv. A, 4.5 micrograms/ml for RSV, and 12.3 micrograms/ml for MSV, respectively. These EC50 values were equivalent to those obtained using the plaque reduction assay. The confluent cell culture system was inadequate for antiviral assays against RSV and MSV when the MTT method was used, because the inhibition of formazan formation was not observed in viral-infected cells. Moreover, the suspension method is more sensitive to the cytotoxicity of antiviral agents than the confluent cell culture system.

Topics: Amides; Animals; Antiviral Agents; Cell Line; Chlorocebus aethiops; Colorimetry; Coloring Agents; Cytidine; Dogs; HeLa Cells; Humans; Influenza A virus; Measles virus; Microbial Sensitivity Tests; Orthomyxoviridae; Pyrazoles; Respiratory Syncytial Viruses; Respirovirus; Ribavirin; Ribonucleosides; Ribose; Sensitivity and Specificity; Tetrazolium Salts; Thiazoles; Vero Cells; Virus Replication

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.

Topics: Adenosine; Amides; Antiviral Agents; Azauridine; Carbon-Nitrogen Ligases; Cell Division; Cytarabine; Cytidine; Deoxycytidine; Drug Synergism; Fluorouracil; HeLa Cells; Humans; Ligases; Nucleosides; Pyrazoles; Ribavirin; Ribonucleosides; Ribose; Thymidine; Tumor Cells, Cultured; Uracil; Virus Replication; Viruses

Several nucleoside analogues which have previously been established as broad-spectrum antiviral agents, i.e. ribavirin, vidarabine, pyrazofurin, tubercidin, carbodine, (S)-9-(2,3-dihydroxypropyl)adenine [(S)-DHPA], carbocyclic 3-deazaadenosine (C-c3 Ado), (RS)-3-adenine-9-yl-2-hydroxypropanoic acid [(RS)-AHPA] isobutyl ester and neplanocin A were compared for their potency and selectivity as inhibitors of human rotavirus (strains Wa, KUN and MO) replication in vitro. As the most efficacious inhibitors emerged (S)-DHPA, C-c3 Ado, (RS)-AHPA isobutyl ester and neplanocin A, with a minimum inhibitory concentration of 60, 1.4, 1.2 and 0.2 micrograms/ml, and a selectivity index of greater than 3, 70, 80 and greater than 20, respectively. As has been postulated for their antiviral action in general, these adenosine analogues probably owe their anti-rotavirus activity to inhibition of S-adenosylhomocysteine hydrolase, a key enzyme in regulating methylations including those that are required for the maturation of viral mRNA.

Topics: Adenine; Adenosine; Amides; Antiviral Agents; Cell Line; Cytidine; Dose-Response Relationship, Drug; Pyrazoles; Ribavirin; Ribonucleosides; Ribose; Rotavirus; Tubercidin; Vidarabine; Virus Replication

Topics: Amides; Antiviral Agents; Cytidine; Dose-Response Relationship, Drug; Guanine; HeLa Cells; Humans; Pyrazoles; Respiratory Syncytial Viruses; Ribavirin; Ribonucleosides; Ribose; Tubercidin; Virus Replication