7-SUBSTITUTED 8-AZA-7-DEAZAPURINES AND 2,8-DIAZA-7-DEAZA-PURINES: SYNTHESIS OF NUCLEOSIDES AND OLIGONUCLEOTIDES

7-Substituted 8-aza-7-deazaadenosines 1a–e were synthesized by Sonogashira cross coupling from the corresponding 7-iodo nucleoside in 36–79% yields. Starting from 7-bromo (or 7-iodo)-8-aza-7-deazaadenine, 2a,b were obtained by acid-catalyzed glycosylation followed by deprotection in 53 and 35% yields, repectively. Compounds 2b was applied to cross coupling reaction to give 2c-d in 34–95% yield. Compounds 2a and 4b were further transformed to the phosphoramidites 5 and 6b in 9 and 49% overall yields, which were incorporated into oligonucleotides.     

7-DEAZAPURIN-2,6-DIAMINE AND 7-DEAZAGUANINE: SYNTHESIS AND PROPERTY OF 7-SUBSTITUTED NUCLEOSIDES AND OLIGONUCLEOTIDES

The synthesis of 7-substituted 7-deazaguanine and 7-deazaadenine ribonucleosides 1–2, the incorporation of 3a–d into oligonucleotides, and the stability of the corresponding duplexes and base discrimination are described. The pK_a values of 3–4 are determined.     

Synthesis of 7-trifluoromethyl-7-deazapurine ribonucleoside analogs and their monophosphate prodrugs

Abstract

Novel 7-trifluoromethyl-7-deazapurine ribonucleoside analogs (13a-c) and their Protides (15a-c) were successfully synthesized from ribolactol or 1-α-bromo-ribose derivatives using Silyl-Hilbert-Johnson or nucleobase-anion substitution reactions followed by key aromatic trifluoromethyl substitution. Newly prepared compounds were evaluated against a panel of RNA viruses, including HCV, Ebola or Zika viruses.     

Oligonucleotides Containing Pyrazolo[3,4-d]Pyrimidines: 8-Aza-7-deazaadenines With Bulky Substituents in the 2- or 7-Position

The synthesis of the 2′-deoxyadenosine analogues 1b, 2b, and 3c modified at the 7- and/or 2-position is described. The effect of 7-chloro and 2-methylthio groups on the duplex stability is evaluated. For that, the nucleosides 1b, 2b, and 3c were converted to the corresponding phosphoramidites 15, 19, and 22, which were employed in the solid-phase oligonucleotide synthesis. In oligonucleotide duplexes, compound 1b forms stable base pairs with dT, of which the separated 1b- dT base pairs contribute stronger than that of the consecutive base pairs. Compound 2b shows universal base pairing properties while its N8 isomer 3c forms duplexes with lower stability.     

Oligonucleotides With Purine Nitrogen-7 as Glycosylation Site

Abstract

The synthesis of phosphoramidites (2 and 3) derived from hypoxanthine and isoguanine N⁷-2¹-deoxyribonucleosides is described. Solid-phase synthesis furnishes oligonucleotides containing N⁷-glycosylated purines. New base pairs between purine N⁷- and N9-nucleosides are proposed.     

Duplex Stability of Oligonucleotides Containing 7-Substituted 7-Deaza- and 8-Aza-7-Deazapurine Nucleosides

Abstract

The synthesis of 7-substituted 7-deaza- and 8-aza-7-deazapurine 2′-deoxyribonucleosides, their incorporation into oligonucleotides, and the stability of corresponding duplexes is described.     

8-Aza-7-deazapurine DNA: Synthesis and Duplex Stability of Oligonucleotides Containing 7-Substituted Bases

Abstract

The 7-substituted 8-aza-7-deazapurine phosphoramidites 1a – 3c as well as the phosphoramidite 4a were synthesized. In comparison to the parent purine oligonucleotide duplexes, the 7-substituted 8-aza-7-deazapurine residues lead to a significant duplex stabilization.     

Synthesis of AZT analogues: 7-(3-azido-2hydroxypropyl)-, 7-(3-amino-2-hydroxypropyl)-, 7-(3-triazolyl-2-hydroxypropyl)theophyllines

Nucleophilic displacement of the tosyloxy group in 7-(2-hydroxy-3-p-toluenesulfonyloxypropyl)theophylline (1) with azide anion afforded 7-(3-azido-2-hydroxypropyl)theophylline (2). Reduction of the 3-azido group in 2 with Ph₃P/Py/NH₄OH afforded the 3-amino derivative 4, alternatively obtained by regioselective amination of 7-(2,3-epoxypropyl)theophylline (3). Selective acetylation of 4 gave the N-acetyl derivative 5. 1,3-Dipolar cycloaddition of the azide group in 2 with N¹-propargyl thymine (6) afforded the regioisomeric triazole 7.     

Synthesis and Anti-HIV Evaluation of 7-Deaza Analogues of Carbovir

Abstract

Three analogues of Carbovir 1 have been synthesized and evaluated for antiviral activity in vitro. Anti-HIV-1 and anti-HIV-2 activities have been observed with 7-deaza analogues 3 and 5 of 1. Compound 5 was about ten times more potent than 3 against HIV-1 and HIV-2 on different cell lines.     

Pyrrolo[2,3-d]Pyrimidine Nucleosides: Synthesis and Antitumor Activity of 7-Substituted 7-Deaza-2′-Deoxyadenosines

Abstract

A one step synthesis, using the nucleoside 7-iodo-2′-deoxytubercidin (2b) in a Pd(0)/Cu(I)-catalyzed cross coupling reaction furnished a series of 7-alkynyl-2′-deoxytubercidin derivatives. The 7-iodo-, 7-chloro- or 7-bromo 2′-deoxytubercidins 2b-d as well as certain 7-alkynyl derivatives show significant activity against several tumor cell lines, with 7-iodo-2′-deoxytubercidin (2b) as the most effective compound.     

Bone Morphogenetic Protein 7 (BMP-7) Influences Tendon-Bone Integration In Vitro

IntroductionSuccessful graft ingrowth following reconstruction of the anterior cruciate ligament is governed by complex biological processes at the tendon-bone interface. The aim of this study was to investigate in an in vitro study the effects of bone morphogenetic protein 7 (BMP-7) on tendon-bone integration.ResultsIn both models, positive effects of BMP-7 on ALP enzyme activity were observed (p<0.001). Additionally, similar results were noted for LDH activity and lactate concentration. BMP-7 stimulation led to a significant increase in OCN expression. Whereas the effects of BMP-7 on tendon monoculture peaked during an early phase of the experiment (p<0.001), the cocultures showed a maximal increase during the later stages (p<0.001). The histological analysis showed a stimulating effect of BMP-7 on extracellular matrix formation. Organized ossification zones and calcium carbonate-like structures were only observed in the BMP-stimulated cell cultures.DiscussionThis study showed the positive effects of BMP-7 on the biological process of tendon-bone integration in vitro. Histological signs of improved mineralization were paralleled by increased rates of osteoblast-specific protein levels in primary bovine osteoblasts and fibroblasts.ConclusionOur findings indicated a role for BMP-7 as an adjuvant therapeutic agent in the treatment of ligamentous injuries, and they emphasized the importance of the transdifferentiation process of tendinous fibroblasts at the tendon-bone interface.     

8-AZA-7-DEAZAADENINE AND 7-DEAZAGUANINE: SYNTHESIS AND PROPERTIES OF NUCLEOSIDES AND OLIGONUCLEOTIDES WITH NUCLEOBASES LINKED AT POSITION-8

The 8-aza-7-deazaadenine (pyrazolo[3,4-d]pyrimidin-4-amine) N⁸-(2′-deoxy-ribonucleoside) (2) and the 7-deazaguanine (pyrrolo[3,4-d]pyrimidine-2-amin-(3H)-4-one) C⁸-(2′-deoxyribonucleoside) (4) were synthesized and incorporated in oligonucleotides employing phosphoramidite chemistry. Oligonucleotides carrying compound 2 are able to form base pairs with the four canonical DNA constituents without significant structural discrimination. The nucleoside 4 was obtained from the corresponding ribonucleoside by deoxygenation. Oligonucleotides containing compound 4 showed similar base pairing properties as those with 2′-deoxyisoguanosine.     

Synthesis of 1, 7-Dideazapurine Ribonucleosides and Deoxyribonucleosides

Abstract

The synthesis of hydroxylamino derivatives of 1,7-dideazaadenosine and of 1,7-dideaza-2′-deoxyadenosine, starting from 4-nitro-1H-pyrrolo[2,3-b]pyridine (1), is described. None of the synthesized compounds are substrates of adenosine deaminase and two of them (3 and 18) are weak inhibitors.     

In vitro impact of amino acid-derived bacterial metabolites on colonocyte mitochondrial activity,oxidative stress response and DNA integrity

Background4-hydroxyphenylacetic acid (HO-PAA) is produced by intestinal microbiota from L-tyrosine. High concentrations in human fecal water have been associated with cytotoxicity, urging us to test HO-PAA's effects on human colonocytes. We compared these effects with those of phenylacetic acid (PAA), phenol and acetaldehyde, also issued from amino acids fermentation.MethodsHT-29 Glc^−/+ human colonocytes were exposed for 24 h to metabolites at concentrations between 350 and 1000 μM for HO-PAA and PAA, 250-1500 μM for phenol and 25-500 μM for acetaldehyde. We evaluated metabolites'cytotoxicity with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide and DNA quantification assays, reactive oxygen species (ROS) production with H2DCF-DA, and DNA damage with the comet assay. We measured cell oxygen consumption and mitochondrial complexes activity by polarography.ResultsAlthough HO-PAA displayed no cytotoxic effect on colonocytes, it decreased mitochondrial complex I activity and oxygen consumption. This was paralleled by an increase in ROS production and DNA alteration. Cells pretreatment with N-acetylcysteine, a ROS scavenger, decreased genotoxic effects of HO-PAA, indicating implication of oxidative stress in HO-PAA's genotoxicity. PAA and phenol did not reproduce these effects, but were cytotoxic towards colonocytes. Last, acetaldehyde displayed no effect in terms of cytotoxicity and mitochondrial metabolic activity, but increased DNA damage.ConclusionsSeveral bacterial metabolites produced from amino acids displayed deleterious effects on human colonocytes, in terms of genotoxicity (HO-PAA and acetaldehyde) or cytotoxicity (PAA and phenol).General significanceThis study helps understanding the consequences of intestinal microbiota's metabolic activity on the host since amino acids fermentation can lead to the formation of compounds toxic towards colonic epithelial cells.     

An immune complex assay for SV40 T antigen.

The two forms of ferredoxin from $\text{Desulfovibrio gigas}$, Fd I and Fd II, are studied by differential pulse polarography 1. Fd I and Fd II give one well defined peak corresponding to $\text{E}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= ?0.33}\text{and}\text{?0.35}$ V (vs. the hydrogen electrode) respectively, at c > 5 μM. The influence of the concentration on the peak potentials Ep and the peak heights i_p is examined. The denaturation of the two forms of ferredoxin is studied by polarography in conjunction with UV spectrophotometry. Two new peaks at negative potentials before the reduction of the solvent are observed in denaturated proteins.     

GRM7 polymorphisms are not associated with ischemic stroke in Iranian population

Abstract

Objectives: Ischemic stroke is the main neurological cause of acquired incapability in adults and a prominent cause of mortality. Several association studies have been conducted to explore the role of candidate genes in this neurological condition.

Methods: In the present study, we aimed at identification of association between Glutamate Metabotropic Receptor 7 (GRM7) and risk of ischemic stroke in Iranian population. Two intronic variants within this gene (rs6782011 and rs779867) were genotyped in 318 sporadic ischemic stroke cases and 300 unrelated, healthy controls individuals.

Results: No significant difference was found in allele, genotype or haplotype frequencies of these SNPs between cases and controls after correction for multiple comparisons.

Conclusion: Consequently, the assessed GRM7 variants are not implicated in risk of ischemic stroke in Iranian population.     

Extraction and analysis of superoxide free radicals (·O−2) from whole mammalian liver

Extraction of whole lobes of normal rat liver with dimethyl sulphoxide (DMSO) under N₂ gives extracts which contain 5—10 μmol/l·O^?₂ (50-100 nmol·O^?₂ per 10 ml extract per 4 g liver; 1.25-2.50 nmol·O^?₂ per millilitre per gram liver). Evidence for ·O^?₂ in the extracts is given by: (1) electron spin resonance signals (ESR), (2) differential pulse polarography (DPP), (3) chemiluminescence (CL), and (4) nitroblue tetrazolium reduction (NBT). All tests yield results identical with those obtained with authentic ·O^?₂. Extraction of ·O^?₂ is enhanced by tetrabutyl ammonium ion, and is maximal at 1-3 min. These results raise the possibility that substantial amounts of ·O^?₂ are normally sequestered in protective membranous sites in vivo.     

Novel thiosemicarbazides induced apoptosis in human MCF-7 breast cancer cells via JNK signaling

Abstract

In this study, novel thiosemicarbazides and 1,3,4-oxadiazoles were synthesized and evaluated for their anticancer effects on human MCF-7 breast cancer cell lines. Among the synthesized derivatives studied, compound 2-(3-(4-chlorophenyl)-3-hydroxybutanoyl)-N-phenylhydrazinecarbothioamide 4c showed the highest cytotoxicity against MCF-7 breast cancer cells as it reduced cell viability to approximately 15% compared to approximately 25% in normal breast epithelial cells. Therefore, we focused on 4c for further investigations. Our data showed that 4c induced apoptosis in MCF-7 cells which was further confirmed by TUNEL assay. Western blotting analysis showed that compound 4c up-regulated the pro-survival proteins Bax, Bad and ERK1/2, while it down-regulated anti-apoptotic proteins Bcl-2, Akt and STAT-3. Additionally, 4c induced phosphorylation of SAPK/JNK in MCF-7 cells. Pretreatment of MCF-7 cells with 10?µM of JNK inhibitor significantly reduced 4c-induced apoptosis. Molecular docking results suggested that compound 4c showed a binding pattern close to the pattern observed in the structure of the lead fragment bound to JNK1. Collectively, the data of current study suggested that the thiosemicarbazide 4c might trigger apoptosis in human MCF-7 cells by targeting JNK signaling.