Publications by authors named "Andrei G"

A group of arabinouridines (TMSEAU, EAU, IEAU-TA) and 2'-deoxyuridines (TMSEDU, EDU, IEDU) having a variety of substituents at the uracil C-5 position (trimethylsilylethynyl, TMSE; ethynyl, E; or iodoethynyl, IE), and the sugar C-2' position (2'-arabino OH in arabinouridine, AU; or 2'-deoxyribo H in 2'-deoxyuridine, DU) were prepared to acquire antiviral structure-activity relationships. A broad-spectrum viral panel screen showed that these 5-alkynylarabino/deoxy-uridines exhibit moderate anti-HSV-1 activity, with no difference in potency between arabinouridines and 2'-deoxyuridines. The 2'-deoxyuridines TMSEDU, EDU, and IEDU, unlike the arabinouridines, exhibited potent antiviral activity against cytomegalovirus, but they were also highly cytostatic.

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A hematopoietic stem cell transplant recipient developed a mucosal herpes simplex virus-1 (HSV-1) infection while under acyclovir (ACV) treatment (HSV was later shown to be resistant to ACV). Concomitantly, the patient presented a hemorrhagic cystitis (HC) due to polyomavirus BK, for which intravenous cidofovir (CDV) was prescribed. The patient benefited from the broad-spectrum anti-DNA virus activity of CDV, and not only the HC resolved without signs of nephrotoxicity but also the HSV-1 lesions disappeared.

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Murine polyomavirus and simian virus 40 were used to evaluate the potencies of the compounds of three classes of acyclic nucleoside phosphonates: (i) the original HPMP (3-hydroxy-2-phosphonomethoxypropyl) and PME (2-phosphonomethoxyethyl) derivatives, (ii) the 6-[2-(phosphonomethoxy)alkoxy]-2,4-diaminopyrimidine (DAPy) derivatives, and (iii) a new class of HPMP derivatives containing a 5-azacytosine moiety. The last class showed the highest activities and selectivities against both polyomaviruses.

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Treatment of 5-azacytosine sodium salt with diisopropyl [(2-chloroethoxy)methyl]phosphonate followed by removal of ester groups with BrSi(CH3)3 afforded 1-[2-(phosphonomethoxy)ethyl]-5-azacytosine (3). Reaction of 5-azacytosine with [(trityloxy)methyl]-(2S)-oxirane followed by etherification with diisopropyl (bromomethyl)phosphonate and removal of ester groups gave 1-(S)-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-azacytosine (1). The synthesis of 6-azacytosine congener 2 was analogous using N4-benzoylated intermediates.

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Acyclic nucleoside phosphonates (ANPs) and in particular (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC, cidofovir, CDV, Vistide) and its adenine counterpart (S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]adenine [(S)-HPMPA] are highly active against orf virus infections. This parapoxvirus commonly causes infection in sheep, goats, but also humans. Alkoxyalkyl esters of CDV have an increased oral bioavailability and are more active against orthopoxviruses than the parent compounds.

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1,3-disubstituted uracils were obtained from uracil by the stepwise alkylation at N-1 and N-3 position with alkyl halide/alkali or alcohol under Mitsunobu conditions. The antiviral activity against HIV-1 of these compounds was examined to find that 1-cyanomethyl-3-(3,5-dimethylbenzyl)uracil and 1-phenyl-3-(3,5-dimethyl-benzyl)uracil showed powerful inhibition.

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Human papillomavirus induces the hyperproliferation of epithelial cells, leading to a broad spectrum of human diseases, ranging from benign warts to malignant neoplasms, depending on the location of the lesion, the immune status of the patient and the type of human papillomavirus. Current therapies for human papillomavirus-associated diseases are based on the excision or ablation of dysplastic or malignant tissue, and are associated with a high frequency of recurrent disease, discomfort and costs. A better understanding of the viral replicative cycle and of the interaction between the virus and the host cell, particularly the cell cycle regulation, has opened new perspectives.

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Cidofovir [(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC)] is recognized as a promising drug for the treatment of poxvirus infections, but drug resistance can arise by a mechanism that is poorly understood. We show here that in vitro selection for high levels of resistance to HPMPC produces viruses encoding two substitution mutations in the virus DNA polymerase (E9L) gene. These mutations are located within the regions of the gene encoding the 3'-5' exonuclease (A314T) and polymerase (A684V) catalytic domains.

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A series of novel 9-substituted (2-(3H-imidazo[1,2-a]purin-3-yl)ethoxy)methylphosphonic and 4-substituted (2-(1H-imidazo[2,1-b]purin-1-yl)ethoxy)methylphosphonic acids as tricyclic etheno analogs of potent antivirals and cytostatics PMEG and PMEDAP was synthesized and evaluated for their biological activity. Most of the compounds showed modest activity against varicella-zoster virus (VZV) and human cytomegalovirus (HCMV) except for (2-(9-oxo-5,9-dihydro-3H-imidazo[1,2-a]purin-3-yl)ethoxy)methylphosphonic acid 8 which proved markedly active against VZV and HCMV. None of the compounds tested exhibited any significant cytostatic effect.

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Researchers are recognizing the limitations of two-dimensional (2D) cell cultures, given the fact that they do not reproduce the morphology and biochemical features that the cells possess in the original tissue. As an alternative, the three-dimensional (3D) cell culture approach offers researchers the possibility to study cell growth and differentiation under conditions that more closely resemble the in vivo situation with regard to cell shape and cellular environment. Currently, 3D culture models are being employed in many areas of biomedical research because they offer a more realistic milieu than 2D cultures.

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The potencies of several alkoxyalkyl esters of acyclic nucleoside phosphonates against vaccinia virus and cowpox virus were evaluated in cell monolayers and three-dimensional epithelial raft cultures. Prodrugs were at least 20-fold more active than their parent compounds. Octadecycloxyethyl-(S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine emerged as the most potent derivative.

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Based on our previous experience with arylsulfone derivatives displaying antiherpetic activity, we synthesized several analogues in which the sulfonyl group is part of a bicyclic structure. The benzene-fused derivative 2H-3-(4-chlorophenyl)-3,4-dihydro-1,4-benzo-thiazine-2-carbonitrile 1,1-dioxide and its thiophene-fused analogue were shown to have favorable activity and selectivity against the betaherpesviruses human cytomegalovirus (HCMV) and human herpesvirus 6 (HHV-6) and 7 (HHV-7). The benzene-fused derivative retained its anti-HCMV activity when evaluated against virus strains resistant to foscarnet, ganciclovir, and/or cidofovir.

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3-(3,5-Dimethylbenzyl)uracil (3) was treated with alkyl halides in the presence of alkali to give 1-substituted congeners. Condensation of 3 with alcohols using the Mitsunobu reaction was also employed as an alternative method. The anti-HIV-1 activity of 1-substituted analogues of 3-(3,5-dimethylbenzyl)uracil was evaluated according to previously established procedures.

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Derivatives of the 2'-deoxynucleoside of furo[2,3-d]pyrimidin-2(3H)-one with long-chain alkyl (or 4-alkylphenyl) substituents at C6 exhibit remarkable anti-VZV (varicella-zoster virus) potency and selectivity, and analogous 2',3'-dideoxynucleoside derivatives show anti-HCMV (human cytomegalovirus) activity. We now report a synthetic approach that enables the preparation of long-chain 6-(alkyn-1-yl)furo[2,3-d]pyrimidin-2(3H)-ones in which the rodlike acetylene spacer replaces the 4-substituted-phenyl ring at C6. Analogues with methyl, beta-d-ribofuranosyl, beta-d-arabinofuranosyl, and 2-deoxy-beta-d-erythro-pentofuranosyl substituents at N3 have been prepared.

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Orf virus, a member of the Parapoxvirus genus, causes a contagious pustular dermatitis in sheep, goats, and humans. Previous studies have demonstrated the activity of (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC; cidofovir; Vistide) against orf virus in cell culture and humans. We have evaluated a broad range of acyclic nucleoside phosphonates (ANPs) against several orf virus strains in primary lamb keratinocytes (PLKs) and human embryonic lung (HEL) monolayers.

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The course of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) and varicella-zoster virus (VZV) infections in squamous epithelial cells cultured in a three-dimensional organotypic raft culture was tested. In these raft cultures, normal human keratinocytes isolated from neonatal foreskins grown at the air-liquid interface stratified and differentiated, reproducing a fully differentiated epithelium. Typical cytopathic changes identical to those found in the squamous epithelium in vivo, including ballooning and reticular degeneration with the formation of multinucleate cells, were observed throughout the raft following infection with HSV and VZV at different times after lifting the cultures to the air-liquid interface.

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Bicyclic furanopyrimidines were recently discovered by us to be potent and selective inhibitors of VZV. Related studies to investigate the role of the sugar in this activity uncovered dideoxy furanopyrimidines as inhibitors of HCMV and this led to the preparation of highly modified long alkyl chain furanopyrimidines from the N- and O-alkylation of their parent bases. Herein we describe their synthesis and subsequent biological evaluation against HCMV.

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2'3'-Dideoxy furanopyrimidines were shown to display anti-HCMV activity via a non-nucleoside mechanism. Further studies into highly modified sugar derivatives led to the preparation of N-and O-alkylated C10 furanopyrimidine analogues, and this work is described herein. These compounds were tested against HCMV strains, and the first case of submicromolar activity was observed.

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Three acyclic nucleoside phosphonates (ANPs) have been formally approved for clinical use in the treatment of 1) cytomegalovirus retinitis in AIDS patients (cidofovir, by the intravenous route), 2) chronic hepatitis B virus (HBV) infections (adefovir dipivoxil, by the oral route), and 3) human immunodeficiency virus (HIV) infections (tenofovir disoproxil fumarate, by the oral route). The activity spectrum of cidofovir {(S)- 1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine [(S)-HPMPC)]}, like that of (S)-HPMPA [(S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]adenine) and (S)-HPMPDAP [(S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]-2, 6-diaminopurine), encompasses a broad spectrum of DNA viruses, including polyoma-, papilloma-, adeno-, herpes-, and poxviruses. Adefovir {9-[2-(phosphonomethoxy)ethyl]adenine (PMEA)} and tenofovir [(R)-9-[2-(phosphonomethoxy) propyl]adenine [(R)-PMPA)]} are particularly active against retroviruses (ie.

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A series of the novel 5-methyl pyrimidine derivatives with an acyclic side chain at the C-6 position were synthesized using lithiation of a 2,4-dimethoxy-5,6-dimethyl pyrimidine and subsequent nucleophilic addition or substitution reactions of the organolithium intermediate thus obtained with acetaldehyde, epichlorhydrine, fluorinated ketones and fluorinated ester. The novel compounds were evaluated for their cytostatic and antiviral activities. Among all the compounds evaluated, two fluorinated acyclic pyrimidine derivatives showed the highest cytostatic activities.

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Objectives: Quinolone derivatives have been shown to inhibit human immunodeficiency virus (HIV) replication at the transcriptional level. Recently, a series of new 6-aminoquinolones that are endowed with more pronounced anti-HIV activities compared with the formerly reported quinolone derivatives have been published. These potent 6-aminoquinolones were further evaluated for their broad-spectrum antiviral properties.

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The remarkably potent and specific activity against varicella-zoster virus (VZV) shown by 2'-deoxynucleosides of furo[2,3-d]pyrimidin-2(3H)-one and related ring systems is dependent on key structural features including the length and nature of the side-chain at C6 and the structure and stereochemistry of the sugar moiety at N3. Removal of the 3'-hydroxyl group from potent anti-VZV 2'-deoxynucleosides results in loss of the VZV activity, but such 2',3'-dideoxynucleoside analogues have shown anti-HCMV activity. We now report acyclic analogues with comparable side-chains at C6, but with the sugar moiety at N3 replaced with the (2-hydroxyethoxy)methyl group (present in the antiherpes drug acyclovir).

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Further to the discovery of bicyclic furanopyrimidine nucleoside analogues (BCNAs) as potent anti-VZV agents, a branched series of this family of compounds was synthesised. The aim was to study the impact of the geometry and steric hindrance in the side chain as well as lipophilic role of this moiety on biological activity. The results showed a detrimental effect of branching on antiviral activity, with a different magnitude depending on the position of branching in the side chain.

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Article Synopsis
  • A variety of herpes simplex virus type 1 clones were studied after being exposed to a high dose of brivudin, leading to mutations primarily in the thymidine kinase (TK) genes.
  • These mutations included 42% frameshift mutations in homopolymer regions and 58% single nucleotide substitutions that either resulted in stop codons or changed existing codons.
  • The A168T substitution was the most frequently selected and showed a link between the genetic changes (genotype), their effects on the virus behavior (phenotype), and how lethal they were in living organisms (in vivo neurovirulence).
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