Synthesis and Biological Activities of Sugar-Modified 2-(p-n-Butylanilino)-2′-deoxyadenosine Analogues

Abstract

Several sugar-modified 2-(p-n-butylanilino)-2′-deoxyadenosine analogues, including arabino and 2′(R)-azido-2′-deoxy analogues and their 5′-triphosphates were synthesized. These nucleosides thus obtained exhibited moderate cytotoxicity against P-388 leukemic cells in culture (IC₅₀ = 13–24 μ). In contrast to above results, the 5′-triphosphates have been shown to exert strong and selective inhibitory effects on mammalian DNA polymerase α (Ki= 0.02–0.04 μ).     

Synthesis and Biological Evaluation of (3′S)-3′-Deoxy-3′-Fluoro-3′-C-Ethynylcytidine

The novel pyrimidine nucleoside, (3 ′S)-3 ′-deoxy-3 ′-fluoro-3 ′-C-ethynylcytidine (1) was synthesized from cytidine in seven steps. The key step in the synthesis was the introduction of the tertiary fluorine at the 3 ′-position. Compound 1 was evaluated in vitro against several RNA viruses.     

Total synthesis of cerebrosides: (2S, 3R, 4E)-1-O-β-d-galactopyranosyl-N-(2′R and 2′S)-2′-hydroxytetracosanoylsphingenine

Total syntheses of both (2S, 3R, 4E)-1-O-β-d-galactopyranosyl-N-(2′R)-2′-hydroxytetracosanoylsphingenine 23 and the (2′S) stereoisomer were performed in an unambiguous way by employing either (2S, 3R, 4E)-N-(2′R)-2′-(tert-butyl-diphenylsilyloxy)tetracosanoylsphingenine or its (2′S) stereoisomer as the key glycosyl acceptors. The synthetic cerebroside 23 was shown to be identical with the natural product through comparison of their 400-MHz, ¹H-n.m.r. spectra, thus providing synthetic evidence for the 2′R configuration of the natural cerebroside.     

Selective synthesis of cerebrosides: (2S, 3R, 4E)-1-O-β-d-galactopyranosyl-N-(2′R and 2′S)-2′-hydroxytetracosanoyl-sphingenine

The cerebrosides were first isolated by Thudicum in 1874 and the structures were established by Carteret al. in 1950 (for review, see [2]). In 1961 Shapiro and Flowers [3] reported the first total synthesis of a cerebroside1 (Fig. 1) which was identified with the natural sample, only through comparison of their i.r. data. In order to confirm the absolute configuration at C-2 of natural cerebroside1, we describe here an unambiguous synthesis of two stereoisomeric cerebrosides1 and2, and found that the¹H-NMR spectra of the synthetic1 (Fig. 2) was completely identical with that of the natural cerebroside reported recently by Dabrowskiet al. [4].In planning the synthetic route, the target structures1 and2 were disconnected at the dotted lines to give three key synthetic intermediates3, 4 and5 or6 (Fig. 1).Abbreviations Bu butyl - Ph phenyl - t-BuPh₂SiCl t-butyldiphenylsilyl chloride - MTPA -methoxy--trifluoromethylphenylacetic acid - THF tetrahydrofuran Part 36 in the series Synthetic Studies on Cell-surface Glycans, for part 35, see [1]     

A Short Syhthesis of 3′-(Methylsulfinyl)-3′-Deoxythymidine and Related Analogues

Abstract

The ring opening of the O-2,3′-anhydrothymidine 5 with the anion of methyl mercaptan gave the 3′-methylthio derivaative 6. Subsequent oxidation and deprotection afforded 3′-(methyl-sulfinyl)-3′-deoxythymidine 2 and its sulfone analogue 3.     

Syntheses of Phosphonate Analogues of Dideoxyadenosine (DDA)-, Dideoxycytidine (DDC)-, Dideoxyinosine (DDI)-, and Deoxythymidine (DDT)-5′-Monophosphates

Abstract

Phosphonate derivatives of ddA, ddC, ddI and ddT (5f, 5e, 5c, and 5a) were prepared by condensing the 5′-aldehydes with diphenyl triphenylphosphoranylidenemethylphosphonate, reducing the resultant olefins and hydrolyzing the phosphonate phenyl esters, sequentially, with base and then C. atrox phosphodiesterase.     

Synthesis,Specific Intracellular Delivery and Biological Activity of Novel Stabilized (2′-5′)(A)n Analogues

Abstract

5’ and 2’ stabilized (2′-5′)(A)_n analogues were synthesized by chemical modifications of enzymatically polymerized (2′-5′)(A)_n oligomers. They exhibit an increased antiviral activity after micro-injection in HeLa cell cytoplasm in agreement with their augmented metabolic stability. Their specific in vitro delivery to mouse leukemia cells after encapsulation in targetted liposomes leads to a transient inhibition of protein synthesis and an antiviral activity.     

Concise syntheses and HCV NS5B polymerase inhibition of (2′R)-3 and (2′S)-2′-ethynyluridine-10 and related nucleosides

(2′R)-Ethynyl uridine 3, and its (2′S)-diastereomer 10, are synthesised in a divergent fashion from the inexpensive parent nucleoside. Both nucleoside analogues are obtained from a total of 5 simple synthetic steps and 3 trivial column chromatography purifications. To evaluate their effectiveness against HCV NS5B polymerase, the nucleosides were converted to their respective 5′-O-triphosphates. Subsequently, this lead to the discovery of the 2′-β-ethynyl 18 and -propynyl 20 nucleotides having significantly improved potency over Sofosbuvir triphosphate 24.     

Synthesis and evaluation of (S,S)-N,N′-bis-[3-(2,2′,6,6′-tetramethylbenzhydryloxy)-2-hydroxy-propyl]-ethylenediamine (S2824) analogs with anti-tuberculosis activity

In order to identify new and potent candidate drugs to treat tuberculosis, a library of compounds was screened, and (S,S)-N,N′-bis-[3-(2,2′,6,6′-tetramethylbenzhydryloxy)-2-hydroxy-propyl]-ethylenediamine (S2824) was identified as a hit in the screen. This research discusses our efforts to synthesize and test 30 analogs of this hit for activity against Mycobacterium tuberculosis. Two compounds with homopiperazine ring possess high in vitro activity against drug sensitive and resistant M. tuberculosis with MICs 0.78–3.13 μg/mL (or 1.22–4.88 μM).     

Synthesis and Biological Activity of 3′-Modified 2′-5′ Adenylate Trimers

Abstract

One of the most important mediators in the mode of action of interferon is the (2′-5′)(A)n synthetase-RNase L pathway. The 2′-5′oligoadenylates (2–5A), synthesized from ATP, activate a pre-existing endonuclease that cleaves single-stranded RNA. The biological activity of 2–5A is rapidly lost due to cleavage of the 2′-5′ internucleotide bond by a specific 2′-5′-phosphodiesterase starting at the 3′end. This rapid cleavage and the poor uptake of 2–5A in intact cells limit the use of 2–5A as an antiviral or antineoplastic agent. Although several modified 2–5A analogues have been synthesized in order to improve the enzymatic stability, only few have proven to be resistant to degradation and still able to activate the 2–5A dependent endonuclease. 1-4 On the other hand, relative drastic methodology such as calcium coprecipitation, microinjection and liposome encapsulation5 has been used to introduce 2–5A into intact cells. Here, we present the synthesis and biological activity of oligoadenylates in which one or more adenosine residues were replaced by 9-(3-azido-3-deoxy-6-D-xylofuranosyl)adenine or 9-(3-amino-3-deoxy-D-xylofuranosyl)adenine. The oligonucleotides were synthesized by the phosphotriester method with triisopropylbenzenesulfonyl-chloride in the presence of N-methylimidazole as the condensing agent. The p-nitrophenylethyl group was used as the protecting group for the 2′-hydroxylfunction .(carbonate), the internucleotide linkage (phosphate ester) and the exocyclic amino groups of the heterocyclic base (carbamate). Bis(p-nitrophenylethy1)phosphoromonochloridate was used to phosphorylate the 5′-hy-droxyl group. All these blocking groups were removed with DBU in pyridine.     

Stannylation Approach to the Synthesis of 2′- and 3′-Substituted Analogues of 2′,3′-Didehydro-2′,3′-dideoxynucleosides

Abstract

Three methods are described for the introduction of a tributylstannyl group to the sp²-carbon of 2′,3′-didehydro-2′,3′-dideoxy nucleosides (d44Ns). The resulting stannylated products serve as versatile intermediates for the synthesis of d4Ns having various types of carbon-substituent.     

Synthesis and Biological Activity of the Mono- and Diamino Analogues of 2′-Deoxyadenosine,Cordycepin, 9-(3-Deoxy-α-D-Threo-Pentofuranosyl)-Adenine (A Structural Component of Agrocin 84) and 9-(2-Deoxy-α-D-Threo-Pentofuranosyl)Adenine

Abstract

The mono- and diamino analogues of 9-(2-deoxy-α-D-erythro-pen-tofuranosyl)adenine la, 9-(2-deoxy-α-D-threo-pentofuranosyl)adenine 4a, 9-(3-deoxy-α-D-erythro-pentofuranosyl)adenine 2a and 9-(3-deoxy-α-D-threo-pentofuranosyl)adenine 3a were synthesized by triphenylphosphine reduction of the corresponding azido compounds. The azido group was introduced by a substitution reaction with lithium azide on mesylates or, more directly, by reaction with lithium azide, triphenylphosphine and carbon tetrabromide. Of the newly synthesized compounds, only 3′-amino-2′,3′-dideoxyadenosine proved, albeit slightly, inhibitory to murine leukemia L1210 and mammary carcinoma FM3A, and human B-lymphoblast Raji, T-lymphoblast Molt/4F and T-lymphocyte MT-4 cell proliferation in vitro (50 % inhibitory dose : 43.1-323 μM). None of the compounds inhibited human immunodeficiency virus-induced cytopathogenicity in MT-4 cells.     

Stereocontrolled Facile Synthesis and Biological Evaluation of (3′S) and (3′R)-3′-Amino (and Azido)-3′-Deoxy Pyranonucleosides

This article describes the synthesis of (3 ′S) and (3 ′R)-3 ′-amino-3 ′-deoxy pyranonucleosides and their precursors (3 ′S) and (3 ′R)-3 ′-azido-3 ′-deoxy pyranonucleosides. Azidation of 1,2:5,6-di-O-isopropylidene-3-O-toluenesulfonyl-α-D-allofuranose followed by hydrolysis and subsequent acetylation afforded 3-azido-3-deoxy-1,2,4,6-tetra-O-acetyl-D-glucopyranose, which upon coupling with the proper silylated bases, deacetylation, and catalytic hydrogenation, obtained the target 3 ′-amino-3 ′-deoxy-β-D-glucopyranonucleosides. The desired 1-(3 ′-amino-3 ′-deoxy-β-D-allopyranosyl)5-fluorouracil was readily prepared from the suitable imidazylate sugar after azidation followed by a protection/deprotection sequence and reduction of the unprotected azido precursor. No antiviral activity was observed for the novel nucleosides. Moderate cytostatic activity was recorded for the 5-fluorouracil derivatives.     

Synthesis and Biological Activity of (±)2′,3′-Dihydroabscisic Acid

An enzyme which catalyzes the oxidation of poly(vinyl alcohol) (PVA) has been purified from a fraction adsorbed to DEAE-Sephadex at pH 7.0 from PVA-degrading enzyme activities produced by a bacterial symbiotic mixed culture in a culture broth when the culture was grown in a minimal medium where PVA served as a sole source of carbon and energy. The enzyme was separated from a coexisting oxidized PVA hydrolase by dye-ligand chromatography on Matrex Gel Blue A. The purified enzyme was homogeneous as judged by polyacrylamide gel electrophoreses in the absence and presence of SDS.

The enzyme is a single polypeptide with a molecular weight of about 40,000 and has an isoelectric point of 4.5. The amino acid composition of the enzyme has been determined and found to have no histidine. The N- and C-terminal amino acid residues are both alanine. The enzyme solution is pink and shows absorption maxima at 276, 364, and 469 nm. One atom of non-heme iron has been detected per molecule in the enzyme.

The enzyme catalyzes the oxidation of PVA and also of various low molecular weight secondary alcohols to the corresponding ketones with the production of H₂0₂ and the consumption of 0₂. The molar ratio of these ketones, H₂0₂ and 0₂ is 1:1:1. The most effective electron acceptor is 0₂, while 2,6-dichlorophenolindophenol and nitro blue tetrazolium also serve as the acceptor with efficiencies to 0₂ of about 31 and 16%, respectively. The enzyme is, therefore, considered to be a secondary alcohol oxidase.

The enzyme is most active at pH 7.0 and at 45°C and is stable between pH 5.0 and 9.0 and at temperatures below 45°C. The activity is inhibited by Hg²⁺ and is restored by the addition of reduced glutathione, although p-chloromercuribenzoate has no effect.

The enzyme shows a common antigenicity in immunodiffusion and neutralization reactions with antisera to a secondary alcohol oxidase previously isolated from another fraction adsorbed on SP-Sephadex at pH 7.0 of the PVA-degrading enzyme activities [Agric. Biol. Chem., 43, 1225 (1979)]. The relations between these two secondary alcohol oxidases are discussed.     

Synthesis of 2-(2′-Hydroxy-2′, 2′-diphenylethyl)-8-hydroxy-quinoline and Its Biological Activity

2-(2′-Hydroxy-2′,2′-diphenylethyl)-8-hydroxyquinoline was prepared via Grignard reaction involving the activated methyl group in position 2. This compound inhibited the action of the phenol oxidase prepared from prepupae of housefly. In a dipping test of the final instar larvae of housefly, it showed some inhibitory effects on the metamorphosis.     

Synthesis and Anti-HIV-1 Activity of Base Modified Analogues of 3′-Azido-2′,3′-Dideoxythymidine (AZT)

Abstract

Analogues of AZT have been synthesized by modifications at the 4-position of the base. Two synthetic routes are described. Among the new compounds, 3′-azido-2′, 3′-dideoxy-4-thiouridine 2b exhibited an unexpectedly marked anti-HIV activity on CEM-C113 cell lines.     

Synthesis,Solution Conformation and Biological properties of 2′,3′-Dideoxy-3′-fluoro-D-erythro-pentofuranosides of 2-Thiouracil and 2-Thiothymine

Abstract

The synthesis of the α- and β-anomers of 2′,3′-dideoxy-3′-fluoro-2-thiouridine and 2′,3′-dideoxy-3′-fluoro-2-thiothymidine via Lewis acid catalysed nucleoside condensation is described. High resolution ¹H NMR data, solution conformations and biological properties are also presented.     

Antioxidative Activity of (-)-Epigallocatechin-3-(3″-O-methyl)gallate Isolated from Fresh Tea Leaf and Preliminary Results on Its Biological Activity

Antioxidative activity of (-)-epigallocatechin-3-(3″-O-methyl)gallate (catechin e) was examined. Catechin e showed a strong antioxidative activity. A preliminary test using rat cancer cells suggests that catechin e also has a strong cytotoxic activity. Among tested catechins, only catechin e has strong activity for both.     

Stereoselective Synthesis of (2R, 3S)-2-Benzyl-2-hydroxy-3- (3,4-methylenedioxybenzyl)-γ-butyrolactone from L-(+)-Arabinose

As a model experiment for the stereoselective synthesis of optically active cis-α,β-dibenzyl-α-hydroxy-γ-butyrolactone, (2R, 3S)-2-benzyl-2-hydroxy-3-(3,4-methylenedioxybenzyl)-γ-butyrolactone (3) was stereoselectively synthesized from L-(+)-arabinose.     

A New Approach for Syntheses of 2′,3′-Dideoxy- 2′,3′-dehydronucleosides Using 2,2-Difluoro- 1,3-dimethylimidazolidine (DFI) as a Dehydrating Reagent

Abstract

We found that 2,2-difluoro-1,3-dimethylimidazolidine (DFI) is useful for not only fluorination but also dehydrating reactions. This dehydrating ability of DFI was applied to the syntheses of dihydrofurans (2) that are possible starting materials for various anticancer or antiviral drugs.