Gussie Arnett

Heterocyclic thiosemicarbazones: correlation between structure, inhibition of ribonucleotide reductase, and inhibition of DNA viruses.

Summary The thiosemicarbazones of 2-formylpyridine, 3-formylpyridine, 4-for-mylpyridine, 5-hydroxy-2-formylpyridine, 1-formylisoquinoline, 5-hydroxy-1-formylisoquinoline, 6-formylpurine, isatin, and 1-methylisatin were examined for activity against herpes simplex virus in H.Ep.−2 cells and human cytomegalovirus in WI-38 cells, and also for inhibition of ribonucleotide reductase activity in H.Ep.−2 cells. A correlation was seen between inhibition of reductase and antiviral activity, with those compounds having the -CH=N-NH-C(=S) -NH2 moiety affixed to the heterocyclic ring system in the position alpha to the ring nitrogen being active. The suggestion is made that the activity of ribonucleotide reductase may be a limiting factor in the replication of certain members of the herpesvirus group.

3-Deazauridine: Inhibition of Ribonucleic Acid Virus-Induced Cytopathogenic Effects In Vitro

3-Deazauridine, a synthetic analogue of uridine and a potential antitumor agent, was found to possess antiviral activity against a number of ribonucleic acid-containing animal viruses in mammalian cell culture. Inhibition of virus-induced cytopathogenic effects by 3-deazauridine was observed in cells infected with rhinovirus types 1A and 13, coxsackievirus type A21, and PR-8 influenza virus, but not in cells infected with poliovirus type 2 or echovirus type 12. The extracellular yield of progeny influenza virus was found to be significantly reduced in titer in 3-deazauridine-treated Madin-Darby canine kidney cell cultures at 12 to 24 hr after infection. Although the precise biochemical mechanism of action of this antimetabolites antiviral activity is not known, the compound does not appear to exert a direct virucidal effect on the influenza virion itself.

Purine analogs as potential anticytomegalovirus agents.

Summary The activity of 25 purine analogs was determined against human cytomegalovirus in vitro. Nineteen compounds were considered to have a degree of antiviral activity with seven of them markedly inhibiting both virus-induced cytopathogenic effects in WI-38 cells and the development of detectable virus. These seven compounds were 2-amino-9-β-d-ribofuranosyl-9H-purine-6-thiol, 2-aminopurine-6-thiol, 9-β-d-arabinofuranosyladenine, purine-6-thiol hydrate, purine-6-carboxaldehyde thiosemicarbazone, 2-amino-6-[(1-methyl-4-nitroimidazol-5-yl) thio] purine, and 9-β-d-ribofuranosyl-9H-purine-6-thiol. The active thiopurines protected the cells from virus infection if allowed to incubate with the cells 1 hr prior to addition of the virus. None of the compounds had demonstrable virucidal activity.

In vitro Effect of a Variety of Biologically Active Compounds on Human Cytomegalovirus

Anticytomegalovirus experiments were carried out on 38 classes of compounds containing 320 materials of known or potential biological activity. All experiments were carried out in tubes using WI-38 cells with the test compounds added within minutes after the virus and then at additional times in medium changes 2 and 4 days later. Antiviral activity was determined by microscopic demonstration of inhibition of viral cytopathogenic effects. Thirty compounds were considered markedly active against the virus. These were the amino acid antagonists aminopterin and N-[3,5-dichloro-4-(2,4-diamino-6-pteridinyl-methylmethylamino)benzoyl]glutamic acid; the unsubstituted lactone, camptothecin; 10 purine analogs, including 8 thiopurines, 9-Β-D-arabinofuranosyladenine and purine-6-carboxaldehyde thiosemicarbazone; 13 pyrimidine analogs and 4 aldehyde thiosemicarbazones.

SYNTHESIS AND ANTIVIRAL EVALUATION OF ANALOGS OF ADENOSINE-N1-OXIDE AND 1-(BENZYLOXY)ADENOSINE

The activity of a series of compounds related to adenosine-N1-oxide (1) and 1-(benzyloxy)adenosine (42) against vaccinia virus has been determined both in vitro and in a vaccinia mouse tailpox model. Significant activities have been found both in vitro and in vivo for a number of the synthetic compounds.

COMPARISON OF THE ANTICYTOMEGALOVIRUS ACTIVITY OF A GROUP OF PYRIMIDINE ANALOGS

We have carried out extensive screening studies with a broad variety of chemical agents using human cytomegalovirus (CMV) in vitro as a test system. From these studies, certain classes of compounds have begun to emerge which apparently have significant activity against this virus. These anti-CMV compounds include purine analogsl, certain thiosemicarbazones (unpublished data), and pyrimidine analogs, with the latter compounds consistently having,the highest degree of activity against the virus. This paper presents the results of quantitative experiments designed to demonstrate comparative structure and antivirus activity relationships within the pyrimidines studied.

Erythro-9-(2-hydroxy-3-nonyl) Adenine alone and in combination with 9-beta-D-arabinofuranosyladenine in treatment of systemic herpesvirus infections in mice.

Although the antiviral activity of erythro-9-(2-hydroxy-3-nonyl)adenine, a potent adenosine deaminase inhibitor, against herpes simplex virus type 1 in cell culture was readily confirmed, the compound was found to be totally ineffective in the treatment of experimentally induced systemic herpes simplex virus type 1 infections in Swiss mice. Data were obtained, however, which clearly indicated that the antiviral potency of 9-beta-D-arabinofuranosyladenine in vivo could be enhanced by the co-administration of low, nontoxic doses of erythro-9-(2-hydroxy-3-nonyl)adenine.

Biological activities and modes of action of 9-α-d-arabinofuranosyladenine and 9-α-d-arabinofuranosyl-8-azaadenine

Abstract From earlier studies it is known that 9-α- d -arabinofuranosyladenine (α-araA) and 9-α- d -arabinofuranosyl-8-azaadenine (α-ara-8-azaA) bave in vitro antiviral activity, are cytotoxic, and are metabolized in mammalian cells to the triphosphates. This study was designed to compare the in vivo antiviral activities of these compounds and their loci of action with those of 9-β- d -arabinofura-nosyladenine (β-araA). the latter compound selectively inhibits DNA synthesis in intact cells, and its triphosphate is a known inhibitor of DNA polymerases and ribonucleotide reductase. Whereas β-araA was significantly effective in the treatment of systemic herpes simplex virus type 1 (HSV-1) infections in mice, α-araA and α-ara-8-azaA were therapeutically ineffective. α-AraATP at a concentration of ~1 mM did not inhibit (1) DNA polymerases present in crude extracts of cultured H.Ep.-2 cells; (2) DNA polymerases present in extracts of KB cells; (3) partially purified DNA polymerase-α from mouse embryo cells; or (4) DNA polymerases induced by HSV-1 and HSV-2. DNA polymerase-β from mouse embryo cells was inhibited to a small extent by 10−4 M α-araATP. In contrast, all of these enzymes were inhibited by β-araATP at a concentration of 10−5M (as shown in these or in earlier studies). the reductions of CDP and UDP by ribonucleotide reductase from L1210 cells were not inhibited by αaraATP (~10−3M), whereas β-araATP produced 70–80 per cent inhibition at this concentration. In cultured H.Ep.-2 cells, α-ara-8-azaA inhibited the incorporation of thymidine, uridine, and formate into macromolecules, but it was without effect on the incorporation of adenine and hypoxanthine, and produced marginal inhibition of the incorporation of leucine. α-Ara-8-azaA produced a dose-dependent inhibition of the accumulation of [14C] formyl-glycinamide ribonucleotide in H.Ep.-2 cells treated with azaserine and [14C] formate. These results indicate that the α-nucleosides inhibit nucleic acid synthesis by mechanisms different from those of β-araA.

Characterization of S-adenosylmethionine decarboxylase induced by human cytomegalovirus infection

Infection of human diploid embryonic lung (MRC5) cells by human cytomegalovirus (HCMV), strain AD169, increased the activity of a key enzyme in the synthesis of polyamines: S-adenosylmethionine decarboxylase (E.C. 4.1.1.50). The initial peak of S-adenosylmethionine decarboxylase activity occurred about 15 h postinfection. S-Adenosylmethionine decarboxylase was purified using a highly specific affinity chromatography step from HCMV-infected and control uninfected MRC5 cells. No difference was found between the two enzymes in their stability to heat or effect of pH on activity. Both enzymes were activated only by putrescine. The appKm for S-adenosylmethionine for the virus-induced enzyme was 1.7 times higher than the appKm for the control enzyme. The most dramatic difference observed was in the effect of high salt concentration on enzyme activity. S-Adenosylmethionine decarboxylase from HCMV-infected cells was unaffected by 0.8 M NaCl, whereas the enzyme from uninfected cells was inhibited by 50% at 0.45 M NaCl and was significantly inhibited at a concentration of 0.8 M NaCl. Thus, different forms of S-adenosylmethionine decarboxylase probably exist in infected and uninfected MRC5 cells.