Synthesis and anti-HIV activities of symmetrical dicarboxylate esters of dinucleoside reverse transcriptase inhibitors

Three nucleoside analogues, 3'-fluoro-2',3'-dideoxythymidine (FLT), 3'-azido-2',3'-dideoxythymidine (AZT), and 2',3'-dideoxy-3'-thiacytidine (3TC) were conjugated with three different dicarboxylic acids to afford the long chain dicarboxylate esters of nucleosides. In general, dinucleoside ester conjugates of FLT and 3TC with long chain dicarboxylic acids exhibited higher anti-HIV activity than their parent nucleosides. Dodecanoate and tetradecanoate dinucleoside ester derivatives of FLT were found to be the most potent compounds with EC(50) values of 0.8-1.0nM and 3-4nM against HIV-1(US/92/727) and HIV-1(IIIB) cells, respectively. The anti-HIV activity of the 3TC conjugates containing long chain dicarboxylate diester (EC(50)=3-60nM) was improved by 1.5-66 fold when compared to 3TC (EC(50)=90-200nM). This study reveals that the symmetrical ester conjugation of dicarboxylic acids with a number of nucleosides results in conjugates with improved anti-HIV profile.     

Design, efficient synthesis, and anti-HIV activity of 4'-C-cyano- and 4'-C-ethynyl-2'-deoxy purine nucleosides

Some 4'-C-ethynyl-2'-deoxy purine nucleosides showed the most potent anti-HIV activity among the series of 4'-C-substituted 2'-deoxynucleosides whose 4'-C-substituents were methyl, ethyl, ethynyl and so on. Our hypothesis is that the smaller the substituent at the C-4' position they have, the more acceptable biological activity they show. Thus, 4'-C-cyano-2'-deoxy purine nucleosides, whose substituent is smaller than the ethynyl group, will have more potent antiviral activity. To prove our hypothesis, we planned to develop an efficient synthesis of 4'-C-cyano-2'-deoxy purine nucleosides (4'-CNdNs) and 4'-C-ethynyl-2'-deoxy purine nucleosides (4'-EdNs). Consequently, we succeeded in developing an efficient synthesis of six 2'-deoxy purine nucleosides bearing either a cyano or an ethynyl group at the C-4' position of the sugar moiety from 2'-deoxyadenosine and 2,6-diaminopurine 2'-deoxyriboside. Unfortunately, 4'-C-cyano derivatives showed lower activity against HIV-1, and two 4'-C-ethynyl derivatives suggested high toxicity in vivo.     

Anti-retroviral and cytostatic activity of 2',3'-dideoxyribonucleoside 3'-disulfides

Herein, we report the synthesis, antiviral and cytostatic effects of nucleosides bearing a 3'-disulfide function as prodrugs of potentially active 3'-mercaptonucleotides. The lack of the anti-HIV effects in mutant CEM/TK-cells for most of the thymidine disulfides suggests that a phosphorylation step involving thymidine kinase is necessary for the eventual antiviral activity of the thymidine nucleosides. The comparable anti-HIV activities of most of the disulfides and their rapid reduction in CEM cell extracts imply an inhibitory effect of the 2',3'-dideoxy-3'-mercaptothymidine 5'-triphosphate metabolite. The cytostatic effects of the disulfides in CEM/0 and Molt4/C8 cells appeared to be strongly dependent on the nature of the non-nucleosidic disulfide moiety and were decreased in preserving the anti-retroviral activity.     

New classes of fluorinated L-nucleosides; synthesis and antiviral activity.

The synthesis of 3'-fluorinated apionucleosides 7 and 2'-fluoro-2',3'-unsaturated L-nucleosides 8 via common synthon, 2-fluoro-butenolide 2, has been described. Among the newly synthesized nucleosides, L-2'-F-d4C, L-2'-F-d4FC and L-2'-F-d4A exhibit significant anti-HIV and anti-HBV activities.     

Synthesis and biological evaluation of 2',4'- and 3',4'-bridged nucleoside analogues

Most nucleosides in solution typically exist in equilibrium between two major sugar pucker forms, N-type and S-type, but bridged nucleosides can be locked into one of these conformations depending on their specific structure. While many groups have researched these bridged nucleosides for the purpose of determining their binding affinity for antisense applications, we opted to look into the potential for biological activity within these conformationally-locked structures. A small library of 2',4'- and 3',4'-bridged nucleoside analogues was synthesized, including a novel 3',4'-carbocyclic bridged system. The synthesized compounds were tested for antibacterial, antitumor, and antiviral activities, leading to the identification of nucleosides possessing such biological activities. To the best of our knowledge, these biologically active compounds represent the first example of 2',4'-bridged nucleosides to demonstrate such properties. The most potent compound, nucleoside 33, exhibited significant antiviral activity against pseudoviruses SF162 (IC(50)=7.0 μM) and HxB2 (IC(50)=2.4 μM). These findings render bridged nucleosides as credible leads for drug discovery in the anti-HIV area of research.     

Synthesis and anti-HIV activity of beta-D-3'-azido-2',3'-unsaturated nucleosides and beta-D-3'-azido-3'-deoxyribofuranosylnucleosides

Since the discovery of 3'-azido-3'-deoxythymidine (AZT) and 2',3'-didehydro-2',3'-dideoxythymidine (d4T) as potent and selective inhibitors of the replication of human immunodeficiency virus (HIV), there has been a growing interest for the synthesis of 2',3'-didehydro-2',3'dideoxynucleosides with electron withdrawing groups on the sugar moiety. Here we described an efficient method for the synthesis of such nucleoside analogs bearing structural features of both AZT and d4T The key intermediate, 3-azido-1,2-bis-O-acetyl-5-O-benzoyl-3-deoxy-D-ribofuranose, 5 was synthesized from commercially available D-xylose in five steps, from which a series of pyrimidine and purine nucleosides were synthesized in high yields. The resultant protected nucleosides were converted to target nucleosides using appropriate chemical modifications. The final nucleosides were evaluated as potential anti-HIV agents.     

Aryl nucleoside H-phosphonates. Part 15: Synthesis, properties and, anti-HIV activity of aryl nucleoside 5'-alpha-hydroxyphosphonates

Aryl nucleoside 5'-H-phosphonates 4 bearing AZT or 2',3'-dideoxyuridine moieties were subjected to reaction with various aromatic aldehydes to produce nucleoside 5'-alpha-hydroxyphosphonate derivatives 2 as potential anti-HIV agents. Stability of the title compounds in cell culture media was investigated and three distinct decomposition pathways were identified. The anti-HIV activity of hydroxyphosphonates 2 correlates well with the type and extent of their chemical or enzymatic degradation in culture medium (RPMI 1640 containing 10% FBS), suggesting that aryl nucleoside 5'-hydroxyphosphonates 2 act as depot forms of the parent antiviral nucleosides.     

Base-Transposed Chiral Isomeric Nucleosides

Abstract

The synthesis and anti-HIV activities of a number of new analogues of basetransposed chiral isomeric nucleosides are described. Modifications of the anti-HIV active compound, (S,S)-isodideoxyadenosine, included both the base and carbohydrate regions.     

The Synthesis and Biological Properties of some Aryl bis(Nucleosid-5′-yl) Phosphates Using Nucleosides with Proven Anti-HIV Activity

Abstract

The synthesis of a series of aryl bis(nucleosid-5′-yl)phosphates in which the nucleosides are either 2′,3′-dideoxy-(d2-) or 2′,3′-didehydro-2′,3′-dideoxy-(d4-) nucleosides is described. These were tested for anti-HIV activity and their efficacy and toxicity compared with the parent nucleosides. Only the 4-(methylsulphonyl)phenyl derivatives of d4T and d2A had any significant activity and had selectivity indices of the same order as the parent nucleosides. These findings can be explained by uptake of the triesters into cells followed by a slow release of nucleoside and nucleotide. In the case of some compounds (such as d2T and d2U) the 5′-monophosphate of which is known to inhibit thymidylate kinase, it is possible that the levels of nucleotide liberated are such that they are not processed into the 5′-triphosphate and hence no antiviral effect is seen.     

Synthesis and evaluation of 3′-azido-2′,3′-dideoxypurine nucleosides as inhibitors of human immunodeficiency virus

Based on the promising drug resistance profile and potent anti-HIV activity of β-d-3′-azido-2′,3′-dideoxyguanosine, a series of purine modified nucleosides were synthesized by a chemical transglycosylation reaction and evaluated for their antiviral activity, cytotoxicity, and intracellular metabolism. Among the synthesized compounds, several show potent and selective anti-HIV activity in primary lymphocytes.     

Synthesis and biological evaluation of L- and D-configuration 1,3-dioxolane 5-azacytosine and 6-azathymine nucleosides

Novel L- and D-configuration dioxolane 5-azacytosine and 6-azathymine nucleosides have been synthesized and evaluated for biological activity. (-)-(2S,4S)-1-[2-(Hydroxymethyl)-1,3-dioxolan-4-yl]-5-azacytosine (6) showed significant activity against HBV, whereas the D-configuration analogue (14) has been found to exhibit potent anti-HIV activity.     

Synthesis and antiviral evaluation of 2',3'-dideoxy-2'-fluoro-3'- C-hydroxymethyl-beta-D-arabinofuranosyl pyrimidine nucleosides

The synthesis and anti-HBV and anti-HIV activity of a number of 2',3'-dideoxy-2'-fluoro-3'-C-hydroxymethyl-beta-D-arabinofuranosyl pyrimidine nucleosides are reported.     

Tri-N-Boc-Tetraazamacrocycle-Nucleoside Conjugates: Synthesis and anti-HIV activities

Abstract

As far as linear N-Boc-polyamines conjugates elicited remarkable anti-HIV activity, the synthesis and anti-HIV properties of cyclic N-Boc-polyamines conjugates such as tetraazamacrocycle-nucleoside were studied. These new conjugates include an ester linkage between the two moieties. They were synthesized using Benzotriazol-l-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate coupling reagent, in the case of N-alkyl polyazamacrocycle derivatives, or through direct condensation of the acyl chloride derivative with nucleoside in the case of N-acyl polyazamacrocycle compounds. None of the new conjugates presented anti-HIV activity greater than that of the corresponding parent nucleosides.     

Synthesis and Anti-HIV Activity of β-D-3′-Azido-2′,3′-unsaturated Nucleosides and β-D-3′-Azido-3′-deoxyribofuranosylnucleosides

Since the discovery of 3′-azido-3′-deoxythymidine (AZT) and 2′,3′-didehydro-2′,3′-dideoxythymidine (d4T) as potent and selective inhibitors of the replication of human immunodeficiency virus (HIV), there has been a growing interest for the synthesis of 2′,3′-didehydro-2′,3′-dideoxynucleosides with electron withdrawing groups on the sugar moiety. Here we described an efficient method for the synthesis of such nucleoside analogs bearing structural features of both AZT and d4T. The key intermediate, 3-azido-1,2-bis-O-acetyl-5-O-benzoyl-3-deoxy-D-ribofuranose, 5 was synthesized from commercially available D-xylose in five steps, from which a series of pyrimidine and purine nucleosides were synthesized in high yields. The resultant protected nucleosides were converted to target nucleosides using appropriate chemical modifications. The final nucleosides were evaluated as potential anti-HIV agents.     

Mass Spectrometry Based Methods for Analysis of Nucleosides as Antiviral Drugs and Potential Tumor Biomarkers

The intracellular analysis of the phosphorylated metabolites of some anti-HIV nucleosides by liquid chromatography or capillary electrophoresis coupled with tandem mass spectrometry (LC-MS/MS or CE-MS/MS) has been realized on human peripheral blood mononuclear cells (PBMC), with limit of quantitation (LOQ) that allow them to be quantitated intracellularly. We described also the analysis of modified urinary nucleosides as potential tumor biomarkers.     

Mass spectrometry based methods for analysis of nucleosides as antiviral drugs and potential tumor biomarkers

The intracellular analysis of the phosphorylated metabolites of some anti-HIV nucleosides by liquid chromatography or capillary electrophoresis coupled with tandem mass spectrometry (LC-MS/MS or CE-MS/MS) has been realized on human peripheral blood mononuclear cells (PBMC), with limit of quantitation (LOQ) that allow them to be quantitated intracellularly. We described also the analysis of modified urinary nucleosides as potential tumor biomarkers.     

Synthesis and biological evaluation of branched and conformationally restricted analogs of the anticancer compounds 3'-C-ethynyluridine (EUrd) and 3'-C-ethynylcytidine (ECyd)

The synthesis of branched and conformationally restricted analogs of the anticancer nucleosides 3'-C-ethynyluridine (EUrd) and 3'-C-ethynylcytidine (ECyd) is presented. Molecular modeling and (1)H NMR coupling constant analysis revealed that the furanose rings of all analogs except the LNA analog are conformationally biased towards South conformation, and are thus mimicking the structure of ECyd. All target nucleosides were devoid of anti-HIV or anticancer activity.     

Ester Derivatives of Nucleoside Inhibitors of Reverse Transcriptase: 2. Molecular Systems for the Combined Therapy with 3′-Azido-3′-Deoxythymidine and 2′,3′-Didehydro-3′-Deoxythymidine

The methods of synthesis of conjugates of anti-HIV nucleosides with various compounds, such as protease inhibitors, peptides, polysaccharides, and bicyclames are considered; they are designated for the combined therapy of HIV.     

Ester derivatives of nucleoside inhibitors of reverse transcriptase: II. Molecular systems for combined therapy with 3'-azido-3'-deoxythymidine and 2',3'-didehydro-3'-deoxythymidine

The methods of synthesis of conjugates of anti-HIV nucleosides with various compounds, such as protease inhibitors, peptides, polysaccharides, and bicyclames, are considered; they are designated for the combined therapy of HIV.     

2'-Fluoro-4'-thio-2',3'-unsaturated nucleosides: anti-HIV activity, resistance profile, and molecular modeling studies

Both D- and L-2'-fluoro-4'-thio-2',3'-unsaturated nucleosides were synthesized and their anti-HIV activity against the drug sensitive virus and lamivudine-resistant mutant (M184V) were evaluated. In vitro antiviral evaluation indicated that the L-isomers are more potent than the D-isomers, but unfortunately all were cross-resistant with 3TC. Molecular modeling studies revealed that the unnatural sugar moiety of the L-nucleosides as well as 4'-sulfur atom of the D-isomer has a steric conflict with the bulky side chain of valine 184, resulting in cross-resistance.