Synthesis, biological activity, and SAR of antimycobacterial 2- and 8-substituted 6-(2-furyl)-9-(p-methoxybenzyl)purines

A number of 6-(2-furyl)-9-(p-methoxybenzyl)purines carrying a variety of substituents in the 2- or 8-position have been synthesized and their ability to inhibit growth of Mycobacterium tuberculosis in vitro has been determined. It is demonstrated that sterical hindrance in the purine 8-position reduces activity and that C-8 should be unsubstituted. In the purine 2-position small, hydrophobic substituents are beneficial. The electronic properties of the 2-substituents appear to have only a minor influence on bioactivity. The compounds studied exhibit low toxicity toward mammalian cells (VERO cells) and are essentially inactive toward Staphylococcus aureus and Escherichia coli. The most active and selective antimycobacterial in the series detected to date is the novel 2-methyl-6-furyl-9-(p-methoxybenzyl)purine with MIC=0.20 microg/mL against M. tuberculosis and IC(50) against VERO cells >62.5 microg/mL. Also the novel 2-fluoro analog and the previously known 2-chloro compound, both with MIC=0.39 microg/mL, are highly interesting drug candidates.     

Discovery of 6-[4-(6-nitroxyhexanoyl)piperazin-1-yl)]-9H-purine,as pharmacological post-conditioning agent

Novel purine analogues bearing nitrate esters were designed and synthesized in an effort to develop compounds triggering endogenous cardioprotective mechanisms such as ischemic preconditioning (IPC) or postconditioning (PostC). The majority of the compounds reduced infarct size compared to the control group in anesthetized rabbits, whereas administration of the most active analogue 16 at a dose of 3.8 μmol/kg resulted on a significant reduction of infarct size, compared to PostC group (13.4 ± 1.9% vs 26.4 ± 2.3%). These findings introduce a novel class of promising pharmacological compounds that could be used as mimics or enhancers of PostC.     

Synthesis and antiviral activity of cyclopropyl-spirocarbocyclic adenosine, (4R,5S,6R,7R)-4-(6-amino-9H-purin-9-yl)-7-(hydroxymethyl)spiro[2.4]heptane-5,6-diol against hepatitis C virus

An efficient method was developed for the synthesis of 6-exocyclic methylene carbocyclic intermediate 4. The Simmons-Smith cyclopropanation protocol was applied on the 6-exocyclic methylene of intermediate 4 and demonstrated its utility for the synthesis of novel class of a spiro-carbocyclic nucleoside analog 8. The titled compound 8 demonstrated a significant antiviral activity against HCV with EC₅₀ values of 0.273 and 0.368 μM in genotypes 1A and 1B, respectively.     

Synthesis, cytostatic and anti-HCV activity of 6-(N-substituted aminomethyl)-, 6-(O-substituted hydroxymethyl)- and 6-(S-substituted sulfanylmethyl)purine nucleosides

An efficient and facile synthesis of a large series of diverse 6-(N-substituted aminomethyl)-, 6-(O-substituted hydroxymethyl)- and 6-(S-substituted sulfanylmethyl)purine nucleosides (55 examples of both ribo- and 2'-deoxyribonucleosides), aimed at identifying novel homologues of natural nucleosides, was developed. The key transformation involved nucleophilic substitutions of Tol-protected 6-(mesyloxymethyl)purine nucleosides by primary or secondary amines, alcoholates or thiolates. While the 2'-deoxyribonucleosides were inactive, the ribonucleosides exerted considerable cytostatic effects and some anti-HCV activity with low selectivity.     

Synthesis, cytostatic, and antiviral activity of novel 6-[2-(dialkylamino)ethyl]-, 6-(2-alkoxyethyl)-, 6-[2-(alkylsulfanyl)ethyl]-, and 6-[2-(dialkylamino)vinyl]purine nucleosides

An efficient and facile synthesis of a large series of diverse 6-[2-(dialkylamino)vinyl]-, 6-[2-(dialkylamino)ethyl]-, 6-(2-alkoxyethyl)-, and 6-[2-(alkylsulfanyl)ethyl]purine nucleosides (35 examples of both ribo- and 2'-deoxyribonucleosides) was developed. The key transformations involved conjugate nucleophilic additions of amines, alcoholates, or thiolates to Tol-protected 6-alkylylpurine or 6-vinylpurine nucleosides. 6-[(2-Dialkylamino)vinyl]- and some 6-[(2-dialkylamino)ethyl]purine ribonucleosides exerted significant cytostatic effects and some anti-HCV activity with low selectivity.     

Radiolabeled guanine derivatives for the in vivo mapping of O(6)-alkylguanine-DNA alkyltransferase: 6-(4-[(18)F]Fluoro-benzyloxy)-9H-purin-2-ylamine and 6-(3-[(131)I]Iodo-benzyloxy)-9H-purin-2-ylamine

Two radiolabeled analogues of 6-benzyloxy-9H-purin-2-ylamine (O(6)-benzylguanine; BG) potentially useful in the in vivo mapping of O(6)-alkylguanine-DNA alkyltransferase (AGT) were synthesized. Fluorine-18 labeling of the known 6-(4-fluoro-benzyloxy)-9H-purin-2-ylamine (FBG; 6) was accomplished by the condensation of 4-[(18)F]fluorobenzyl alcohol with 2-aminopurin-6-yltrimethylammonium chloride (4) or 2-amino-6-chloropurine in average decay-corrected radiochemical yields of 40 and 25%, respectively. Unlabeled 6-(3-iodo-benzyloxy)-9H-purin-2-ylamine (IBG; 7) was prepared from 4 and 3-iodobenzyl alcohol. Radioiodination of 9, prepared from 7 in two steps, and subsequent deprotection gave [(131)I]7 in about 70% overall radiochemical yield. The IC(50) values for the inactivation of AGT from CHO cells transfected with pCMV-AGT were 15 nM for IBG and 50 nM for FBG. The binding of [(18)F]6 and [(131)I]7 to purified AGT was specific and saturable with both exhibiting similar IC(50) values (5-6 microM).     

huGM-CSF(9-127)-IL-6(29-184)融合蛋白的复性及纯化研究

利用Q Sepharose H.P.离子交换柱层析在8mol/L尿素变性条件下对huGM-CSF(9-127)-IL-6(29-184)融合蛋白进行初步纯化,然后再利用Sephacryl S-200分子筛柱层析复性及纯化后获得目的蛋白,其纯度达到95%以上。该纯化方案成功地解决了稀释复性或透析复性产物在进行Q Sepharose H.P.离子交换柱层析时目的蛋白不稳定而沉积于柱上的问题,获得了较好的复性效果,复性率达到80%以上。使用该纯化方案,1天内便可基本完成重组蛋白的复性及纯化过程,而且也便于扩大。     

huGM-CSF(9-127)-IL-6(29-184)融合蛋白的复性及纯化研究

利用Q Sepharose H.P.离子交换柱层析在8mol/L尿素变性条件下对huGM-CSF(9-127)-IL-6(29-184）融合蛋白进行初步纯化,然后再利用Sephacryl S-200分子筛柱层析复性及纯化后获得目的蛋白,其纯度达到95％以上。该纯化方案成功地解决了稀释复性或透析复性产物在进行Q Sepharose H.P.离子交换柱层析时目的蛋白不稳定而沉积于柱上的问题,获得了较好的复性效果,复性率达到80％以上。使用该纯化方案,1天内便可基本完成重组蛋白的复性及纯化过程,而且也便于扩大。     

9-[(10-(aden-9-yl)-4,8-diazadecyl)amino]-6-chloro-2-methoxy-acridine incises DNA at apurinic sites.

The incision of DNA at apurinic/apyrimidinic sites (AP-sites) by chloro-6-methoxy-2 [(adenyl-9)-11)-4,8 diazadecyl]amino-9 acridine (Ade-Z-Acr), a 9-aminoacridine linked to an adenine, at nanomolar concentrations is described. Moreover, this drug, Ade-Z-Acr, is one of the most efficient drugs which cleaves DNA at AP-sites. The high activity is the result of the composition of the drug, since the individual components have no incising activity in the concentration range studied. The termini left by the Ade-Z-Acr molecule are a 3'deoxyribose and a 5'nucleotide. The termini and the inability of the Ade-Z-Acr to incise DNA with reduced AP-sites suggest that the mechanism of cleavage is beta-elimination.     

Synthesis of 1,5-Anhydro-2-(N 6-Cyclopentyladenin-9-Yl)-2-Deoxy-D-Altrohexitol

Abstract

The N ⁶-cyclopentyladenosine (CPA) analogue (4) was synthesized in 10 steps starting from glucose. The results of the radioligand binding assays are consistent with the thus far published findings that compounds containing a six-membered moiety at N ⁹ exhibit extremely weak affinity for adenosine receptors. Replacement of the ribofuranosyl moiety of CPA (2) by a 2-deoxy-D-altrohexitol moiety is sufficient to completely abolish its agonist activity.     

Synthesis and Biological Properties of 9-(2, 4-Dihydroxybutyl) Adenine and Guanine: New Analogues Of 9-(2, 3-Dihydroxyprqpyl)adenine (Dhpa) and 9-(2-Hydroxyethoxymethyl)guanine (Acyclovir)

Abstract

New analogues of antiviral agents 9-(2, 3-dihy-droxyproply) adenine (DHPA, 1a.) and 9-(2-hydroxyethoxymethyl) guanine (acyclovir, Ib) - compounds Ic and Id were prepared and their biological activity was investigated. Racemic 1, 2, 4-butanetriol (2) was converted to the corresponding benzylidene derivative (3a) by acetalation with benzalde-hyde and triethyl orthoformate. Acetal 3a and p-toluene- sul-fonyl chloride in pyridine gave the corresponding p-toluenes fonate 3b. Alkylation of adenine 5a via sodium salt of 5a with 3b in dimethylformamide or in the presence of tetra-n-butylammonium fluoride in tetrahydrofuran gave intermediate 6a. Reaction of 2-amino-6-chloropurine (5b) with 3b effected by K₂CO₃ in dimethylsulfoxide gave compound 6b and a smaller amount of 7-alkylated proauct 7. A similar transformation catalyzed by tetra-n-butylammonium fluoride afforded only intermediate 5b. Acid-catalyzed de-protection (hydrolysis) of 6b and 6a gave the title compounds Ic and Id. The S-enantiomer of Ic was deaminated with adenosine deaminase. Our results argue against the presence of a methyl group-binding site of adenosine deaminase. Compounds Ic and Id exhibited little or no activity in antiviral assays with several DNA and RNA viruses.     

Radical-Mediated Cyclization of A 6-Chloro-9-(2-Deoxy--d erythro-pent-1-enofuranosyl)-8-(2,2-dibromovinyl) purine

Abstract

A vinyl radical generated from a 6-chloro-9-(2-deoxy--d eryrhro-pent-l-enofuranosyl)-8-(2,2-dibromovinyl) purine effected cyclization either at the 1′-or at the 2′-position. The result is discussed in comparison with our previous study of the corresponding uracil derivative.     

Synthesis of 6-alkyl- and arylamino-9-(tetrahydro-2-pyranyl)purines via 6-methylsulfonylpurine

A series of six potential plant hormones, 6-alky- and arylamino-9-(tetrahydro-2-pyranyl)purines were prepared in three steps in 35 to 45% overall yield from 6-methylthiopurine via 6-methylsulfonylpurine.     

Synthesis of 6-Alkyl- and Arylamino-9-(tetrahydro-2-pyranyl)purines via 6-Methylsulfonylpurine

Abstract

A series of six potential plant hormones, 6-alky- and arylamino-9-(tetrahydro-2-pyranyl)purines were prepared in three steps in 35 to 45% overall yield from 6-methylthiopurine via 6-methylsulfonylpurine.     

Synthetic approaches to 6-substituted 9-(3-azido-3,4-dideoxy-β-d,l-erythro-pentopyranosyl)purines

Methyl 3-azido-2-O-benzoyl-3,4-dideoxy-β-dl-erythro-pentopyranoside (6) was synthesized through two routes in five steps from methyl 2,3-anhydro-4-deoxy-β-dl-erythro-pentopyranoside (1). The first route proceeded via selective azide displacement of the 3-tosyloxy group of methyl 4-deoxy-2,3-di-O-tosyl-α-dl-threo-pentopyranoside, followed by detosylation and benzoylation. The second route consisted, with a better overall yield, in the azide displacement of the mesyloxy group of methyl O-benzoyl-4-deoxy-3-O-methylsulfonyl-α-dl-threo-pentopyranoside (10), obtained by benzylate opening of 1, followed by benzoylation, debenzylation, and mesylation. Compound 6 was transformed into its glycosyl chloride, further treated by 6-chloropurine to give the nucleoside 9-(3-azido-2-O-benzoyl-3,4-dideoxy-β-dl-erythro-pentopyranosyl)-6-chloropurine (13). When treated with propanolic ammonia, 13 yielded 9-(3-azido-3,4-dideoxy-β-dl-erythro-pentopyranosyl)adenine.