Electrochemical Analysis of 3′-Azidothymidine (AZT)

Abstract

3′-Azido-3′-deoxythymidine (AZT) exhibits a two-electron diffusion—controlled polarographic reduction wave, with conversion to 3^′?amino-3′-deoxythymidine. The mechanism of reduction, analytical and clinical applications, and its use for one-step synthesis of amino from azido nucleosides, are described.     

Partial trisomy of the short arm of chromosome 3 (3p25→3pter)

Summary Two profoundly mentally mentally retarded brothers with partial trisomy for the distal part of the short arm of chromosome 3 (3p253pter) are described. Their anomaly arose as a segregation product of a balanced t(3p-;18q+) translocation in the mother. Compared with the other cases of partial 3p trisomy reported up to now, the present patients display a similar craniofacial dysmorphism with hypertelorism, broad nasal tip, short upper lip with prominent philtrum, and a large mouth with down-turned corners. Other stigmata, such as a prominent, high forehead with frontal bossing and full cheeks, were present during childhood but progressively disappeared.     

Synthesis of 2-(3-Deoxy-β-D-erythropentofuranosyl)-thiazole-4-carboxamide (3′-Deoxytiazofurin)

Abstract

2-(3-Deoxy-β-D-erythropentofuranosyl)-thiazole-4-carboxamide was synthesized in four steps from its β-D-ribofuranosyl nucleoside precursor.     

Synthesis and characterization of [Pt(COD)Cl(NO3)] and [Pt(COD)(NO3)2] and the use of [Pt(COD)Clx(NO3)2−x] in the preparation of cis[Pt(PPh3)2Clx(NO3)2−x] (x=0, 1, 2) and [Pt(PPh3)3L](NO3) (L=Cl,NO3)

[Pt(COD)Cl₂] (COD=1,5-cyclooctadiene) is a versatile starting material for the synthesis of Pt(II) compounds. The preparations of the new compounds [Pt(COD)Cl(NO₃)], [Pt(COD)(NO₃)₂] and [Pt(PPh₃)₃(NO₃)](NO₃) and also of the known compounds cis[Pt(PPh₃)₂Cl₂], cis [Pt(PPh₃)₂Cl(NO₃)], cis[Pt(PPh₃)₂(NO₃)₂] and [Pt(PPh₃)₃Cl](NO₃)are reported. The compounds are characterized by elemental analysis, ³¹P{¹H} NMR spectroscopy and IR spectroscopy.     

C-Nucleosides via Glycosyl Alkynyl Ketones. Synthesis of 5(3)-Phenyl-3(5)-(β-D-ribofuranosyl) Pyrazole

Abstract

A β-D-ribofuranosyl phenylethynyl ketone (3) has been synthesized and shown to be a suitable intermediate for heterocyclic elaboration to C-nucleosides. Cyclization of 3 with hydrazine hydrate produces the title C-nucleoside.     

Cystine-knot peptides engineered with specificities for α(IIb)β(3) or α(IIb)β(3) and α(v)β(3) integrins are potent inhibitors of platelet aggregation

A truncated form of the Agouti‐related protein (AgRP), a member of the cystine‐knot family, has shown promise as a scaffold for engineering novel peptides with new molecular recognition properties. In this study, we replaced a constrained six amino acid loop in AgRP with a nine amino acid loop containing an Arg–Gly–Asp integrin recognition motif, and randomized the neighboring residues to create a library of ～20 million AgRP variants. We displayed the AgRP mutants as fusions on the surface of yeast and used high‐throughput fluorescence‐activated cell sorting (FACS) to isolate peptides that bound specifically to the platelet integrin α_IIbβ₃, a clinically important target for the prevention and treatment of thrombosis. These AgRP peptides had equilibrium dissociation (K_D) constants for α_IIbβ₃ integrin ranging from 60 to 90 nM, and did not bind to α_vβ₃, α_vβ₅, or α₅β₁ integrins. Using an alternate library screening strategy, we identified AgRP peptides that bound to both α_IIbβ₃ and α_vβ₃ integrins with K_D values ranging from 40 to 70 nM and 20 to 30 nM, respectively, and did not bind to α_vβ₅ or α₅β₁ integrins. Unique consensus sequences were identified within both series of AgRP peptides suggesting alternative molecular recognition events that dictate different integrin binding specificities. In addition, the engineered AgRP peptides prevented platelet aggregation as well as or slightly better than the FDA‐approved cyclic peptide eptifibatide. Collectively, these data demonstrate that cystine‐knot peptides can be generated with high affinity and specificity to closely‐related integrins, and provide insights into molecular interactions between small, structured peptide ligands and their receptors. Copyright © 2010 John Wiley & Sons, Ltd.     

Microbial production of (R)-3-halolactic acid from (±)-3-halo-1,2-propanediol

Microbial oxidation of (±)-3-halo-1,2-propanediol was studied and it was found that several microorganisms accumulated (R)-3-halolactic acid. Geotrichum loubieri CBS 252.61 produced the most and gave optically pure (R)-3-chlorolactic acid and (R)-3-bromolactic acid from the corresponding diols.     

Acidic extracellular pH promotes activation of integrin α(v)β(3)

Acidic extracellular pH is characteristic of the cell microenvironment in several important physiological and pathological contexts. Although it is well established that acidic extracellular pH can have profound effects on processes such as cell adhesion and migration, the underlying molecular mechanisms are largely unknown. Integrin receptors physically connect cells to the extracellular matrix, and are thus likely to modulate cell responses to extracellular conditions. Here, we examine the role of acidic extracellular pH in regulating activation of integrin α(v)β(3). Through computational molecular dynamics simulations, we find that acidic extracellular pH promotes opening of the α(v)β(3) headpiece, indicating that acidic pH can thereby facilitate integrin activation. This prediction is consistent with our flow cytometry and atomic force microscope-mediated force spectroscopy assays of integrin α(v)β(3) on live cells, which both demonstrate that acidic pH promotes activation at the intact cell surface. Finally, quantification of cell morphology and migration measurements shows that acidic extracellular pH affects cell behavior in a manner that is consistent with increased integrin activation. Taken together, these computational and experimental results suggest a new and complementary mechanism of integrin activation regulation, with associated implications for cell adhesion and migration in regions of altered pH that are relevant to wound healing and cancer.     

Seven members of the (1→3)-β-glucanase gene family in barley (Hordeum vulgare) are clustered on the long arm of chromosome 3 (3HL)

Members of the (13)--glucan glucanohydrolase (EC 3.2.1.39) gene family have been mapped on the barley genome using three doubled haploid populations and seven wheat-barley addition lines. Specific probes or polymerase chain reaction (PCR) primers were generated for the seven barley (13)--glucanase genes for which cDNA or genomic clones are currently available. The seven genes are all located on the long arm of chromosome 3 (3HL), and genes encoding isoenzymes GI, GII, GIII, GIV, GV and GVII (ABG2) are clustered in a region less than 20 cM in length. The region is flanked by the RFLP marker MWG2099 on the proximal side and the Barley Yellow Mosaic Virus (BYMV) resistance gene ym4 at the distal end. The gene encoding isoenzyme GVI lies approximately 50 cM outside this cluster, towards the centromere. With the exception of the gene encoding isoenzyme GIV, all of the (13)--glucanase genes are represented by single copies on the barley genome. The probe for the isoenzyme GIV gene hybridized with four DNA bands during Southern blot analysis, only one of which could be incorporated into the consensus linkage map.     

Synthesis of New 5″-Sulfonylamido Derivatives of 3″-Azido-3″-Deoxythymidine (AZT)

Abstract

A series of 5′-N-methanesulfonyl derivatives of 3′-azido-5′-(alkylamino)-3′,5′-dideoxythymidine was synthesised. The first step of the synthesis involved the reaction of 1-(2,5-dideoxy-5-O-tosyl-β-D-threo-pentofuranosyl)thymine 1 with an appropriate amine to give 1-[5-(alkylamino)-2,5-dideoxy-β-D-threo-pentofuranosyl]thymines 2a-e and 1-(2,5-dideoxy-β-threo-pent-4-enofuranosyl)thymine 3 as a by-product. Compounds 2a-e were treated with an excess of methanesulfonyl chloride to yield intermediates 1-[5-(dimethylamino)-3-O-methanesulfonyl-2,3,5-trideoxy-β-D-threo-pentofuranosyl]-thymine 4a and 1-[5-(N-alkyl-N-methanesulfonyl)-3-O-methanesulfonyl-2,3,5-trideoxy-β-D-threo-penfuranosyl]thymines 4b-e. The reaction of 4a-e with lithium azide in dimethyl-formamide afforded the final compounds 1-[3-azido-5-(N-methyl-N-methanesulfonyl)-2,3,5-trideoxy-β-D-erythro-penofuranosyl]thymine 5a and 1-[3-azido-5-(N-alkyl-N-methanesulfonyl)-2,3,5-trideoxy-β-D-erythro-penofuranosyl]thymines 5b-e. The independent synthesis of 4′,5′-unsaturated product 3 was also described.     

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.     

Glycogen synthase kinase 3β (GSK3β) modulates antiviral activity of zinc-finger antiviral protein (ZAP)

Zinc-finger antiviral protein (ZAP) is a host factor that specifically inhibits the replication of certain viruses, including HIV-1, Ebola virus, and Sindbis virus. ZAP binds directly to specific viral mRNAs and recruits cellular mRNA degradation machinery to degrade the target RNA. ZAP has also been suggested to repress translation of the target mRNA. In this study, we report that ZAP is phosphorylated by glycogen synthase kinase 3β (GSK3β). GSK3β sequentially phosphorylated Ser-270, Ser-266, Ser-262, and Ser-257 of rat ZAP. Inhibition of GSK3β by inhibitor SB216763 or down-regulation of GSK3β by RNAi reduced the antiviral activity of ZAP. These results indicate that phosphorylation of ZAP by GSK3β modulates ZAP activity.     

Discovery of novel 2-piperidinol-3-(arylsulfonyl)quinoxalines as phosphoinositide 3-kinase α (PI3Kα) inhibitors

A series of novel 2-aliphatic cyclic amine-3-(arylsulfonyl)quinoxalines was synthesized based on the structural features of a previously identified lead, WR1. The 2-piperidinol-3-(arylsulfonyl)quinoxalines, which showed excellent antitumor activities against five human cell lines, with inhibitory activities ranging from 0.34 to 2.32 μM, proved to be a promising class of novel PI3Kα inhibitors. The most potent compound 10d (WR23) showed an inhibitory IC(50) value of 0.025μM against PI3Kα and significant pAkt suppression effect. Molecular docking analysis was performed to determine possible binding modes between PI3Kα and target compounds.     

Absorption of DNA in the region of vacuum-uv (3–25 eV)

By means of a device that might be considered a modern version of "Ulbricht's sphere" the absorption spectrum and the photoelectric emission of calf thymus DNA was measured in the region of 3 to 25 eV (400 to 50 nm). A tentative explanation of the general shape of the absorption spectrum and of its 6 maxima is given. The results permit a much better insight into some biologic effects of vacuum-uv to be gained than hitherto possible.     

Discovery and anti-inflammatory evaluation of benzothiazepinones (BTZs) as novel non-ATP competitive inhibitors of glycogen synthase kinase-3β (GSK-3β)

Glycogen synthase kinase-3β (GSK-3β) has been identified to promote inflammation and its inhibitors have also been proven to treat some inflammatory mediated diseases in animal models. Non-ATP competitive inhibitors inherently have better therapeutical value due to their higher specificity than ATP competitive ones. In this paper, we designed and synthesized a series of new BTZ derivatives as non-ATP competitive GSK-3β inhibitors. Kinetic analysis revealed two typical compounds 6j and 3j showed the different non-ATP competitive mechanism of substrate competition or allosteric modulation to GSK-3β, respectively. As expected, the two compounds showed good specificity in a panel test of 16 protein kinases, even to the closest enzymes, like CDK-1/cyclin B and CK-II. The in vivo results proved that both compounds can greatly attenuate the LPS-induced acute lung injury (ALI) and diminish inflammation response in mice by inhibiting the mRNA expression of IL-1β and IL-6. Western blot analysis demonstrated that they negatively regulated GSK-3β, and the mechanism of the observed beneficial effects of the inhibitors may involve both the increased phosphorylation of the Ser9 residue on GSK-3β and protein expression of Sirtuin 1 (SIRT1). The results support that such novel BTZ compounds have a protective role in LPS-induced ALI, and might be attractive candidates for further development of inflammation pharmacotherapy, which greatly thanks to their inherently high selectivities by the non-ATP competitive mode of action. Finally, we proposed suggesting binding modes by Docking study to well explain the impacts of compounds on the target site.     

Computational DNA binding studies of (–)-epigallocatechin-3-gallate

The catechin family of molecules that are present in the leaves of green tea has been under investigation since the antioxidant and anti-inflammatory properties of tea were discovered. Among multiple proposed therapeutic targets of these molecules, the direct interaction with nucleic acids has been proposed and experimentally observed but without clear knowledge about the potential binding modes between these ligands and DNA. One of these catechin structures, (–)-epigallocatechin gallate (EGCG), has three aromatic rings that could interact with double-stranded DNA via terminal base-pair stacking, intercalation, or through groove binding. Using enhanced sampling techniques and molecular dynamics simulations, we have found a stable complex between the EGCG ligand and DNA through intercalation of the trihydroxybenzoate aromatic ring and an ApC step. Moreover, we have calculated the absorption spectra of four possible binding modes and compared these to absorption profiles reported in the literature, and explored the possible DNA sequence preference for the EGCG ligand to bind. Our results suggest that an intercalative mode of interaction through the major groove is possible between the EGCG ligands and DNA with apparently very little DNA sequence selectivity.     

Conformation of (1→3)-α-D-Glucan Tribenzoate

The molecular conformation of (1→3)-α-D-glucan tribenzoate (TBG) was studied by X-ray diffraction measurements coupled with a conformational analysis. Although the fiber pattern obtained was of very low crystallinity, the presence of a meridional reflection at the 5th layer line indicated that the TBG molecule took a five-fold helical conformation with a 19.63 A fiber repeat. A conformational analysis on the five-fold helix, which was done by calculating van der Waals’ repulsion energy between non-bonded atoms comprising the TBG chain, suggested that the most preferable energy-based conformation was –5/1, a left-handed five-fold helix.