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.     

Novel Spironucleosides: 1″,3″-Thiazolidine-2″-Spiro-3′-3′-Deoxyuridine Derivatives

Abstract

Reaction of 2′,5′-di-O-TBDMS-3′-ketouridine 1 with L-cysteine yielded in good yield a resolvable mixture of the two expected epimeric spironucleosides 2 and 3. Amidification of their carboxylic group took place readily and the ribo carboxamide 4 was oxidized to the corresponding sulfoxide 6. Despite their similarity to TSAO derivatives these compounds did not exhibit usable anti-HIV activity.     

Apigenin 7-glucoside and its 2″- and 6″-acetates from ligulate flowers of Matricaria chamomilla

Dried ligulate flowers of Matricaria chamomilla contain 7–9% glucosides of apigenin and 0.3–0.5% free apigenin. Glucosides were identified as apigenin 7-glucoside and a 1:3 mixture of the 2″- and 6″-acetates, as determined by ¹³C NMR analysis.     

Syntheses of 2″,3″-Dideoxy-L-Glycero-Pentofuranosyl C-Nucleosides

Abstract

2′,3′ -Dideoxy-L-C-nucleosides, 4-amino-8-(2,3-dideoxy-L-glyceropento-furanosyl)pyrazolo[1,5-a]-1,3,5-triazines (9 and 10), 4-amino-7-(2,3-dideoxy-L-glycero-pentofuranosyl)-3H,5H-pyrrolo[3,2-d]pyrimidines (17 and 18), 7-(2,3-dideoxy-L-glyceropentofuranosyl)-4-oxo-3H,5H-pyrrolo[3,2-d]pyrimidines (23 and 24) and 2,4-diamino-5-(2,3-dideoxy-L-glyceropentofuranosyl)pyrimidines (28 and 29) have been synthesized from L-gulonic γ-lactone 1.     

Synthesis and Properties of O-β-D-Ribofuranosyl-(1″-2′)-Adenosine-5″-O-Phosphate and Its Derivatives

Abstract

The synthesis of O-β-D-ribofuranosyl-(1″-2′)-adenosine-5″-O-phosphate and its suitably protected derivative for oligonucleotide synthesis have been developed.     

Synthesis of [1-[2′,5′-bis-O-(t-Butyldimethylsilyl)-β- L-ribofuranosyl] thymine]-3′-spiro-5″-(4″-amino-1″,2″-oxathiole-2″,2″-dioxide) (L-TSAO-T)

Abstract

Derivatives of TSAO-T based upon pentofuranose sugars with the L-configuration have been prepared and evaluated as inhibitors of HIV-1 induced cytopathicity.     

The efficacy and acceptability of the ″prostaglandin impact″ in inducing complete abortion during the second week after the missed menstrual period

Twenty-two pregnant patients were exposed, 12±1 days after their missed menstrual period, to a single intrauterine dose of 5mg PG F2_α, to provoke a PG ″Impact″ (PGI) and through it legal abortion. The PGI, delivered through the cervix during 10 minutes, induced 83±9mm Hg contracture in 20±3 minutes. Cyclic IUP reached 102±10mm Hg only in 116±14 minutes, it was then sustained for about 2 hours and subsequently declined.During the evolution of IUP uterine bleeding appeared, progesterone (P) and estradiol 17_β (E₂) started to decrease and continued decreasing. At 24 hours after PGI, P-withdrawal was 44% (P<0.05), bleeding continued and cervical dilatation approximated 1cm. Subsequently uterine bleeding (containing tissue fragments) continued and out of 22 women 20 aborted completely. After 3–5 days bleeding declined, the pregnancy tests became negative and normal menstrual periods one month after PGI provided the desired end points of the study. Complete abortions, simulating the symptoms of delayed menstrual periods, had a high Abortion Score of 95 and in the sedated patients the side effects were infrequent, mild and acceptable. This clinical outcome encourages extensive field trials.None of the patients aborted during the short lived period of exogenous PG stimulation. However, the continued steroid withdrawals indicated that PGI damaged the endocrine function of the ovum and the luteotrophic support of the corpus luteum. Therefore, if it was PG which completed abortion eventually, it had to be the endogenous compound, having become effective in physiological concentrations, due to the threshold-lowering action of P-withdrawal.     

Human U2B″ protein binding to snRNA stemloops

The human U2B″ protein is one of the unique proteins that comprise the U2 snRNP, but it is also a representative of the U1A/U2B″ protein family. In the U2 snRNP, it is bound to Stem-Loop IV (SLIV) of the U2 snRNA. We find that in vitro it binds not only to human SLIV, but also to Stem-Loop II (SLII) from human U1 snRNA and to Drosophila U2 snRNA SLIV. The thermodynamics of these binding interactions show a striking similarity, leading to the conclusion that U2B″ has a relaxed specificity for its RNA targets. The binding properties of U2B″ are distinct from those of human U1A and of Drosophila SNF, despite its high homology to those proteins, and so provide important new information on how this protein family has modulated its target preferences.     

Two isovitexin 2″-O-glycosides from primary leaves of Secale cereale

Two isovitexin 2″-O-glycosides have been isolated from primary leaves of rye and identified as isovitexin 2″-O-arabinoside and isovitexin 2     

Synthesis of 4″-O-desosaminyl clarithromycin derivatives and their anti-bacterial activities

A series of new 4″-O-desosaminyl clarithromycin derivatives were designed and synthesized. The efficient synthesis routes of 6-deoxy-desosamine donors 8 and 11 were developed and the methodology of glycosylation of clarithromycin 4″-OH with desosamine was studied. The activities of the target compounds were tested against a series of macrolide-sensitive and macrolide-resistant pathogens. Some of them showed activities against macrolide sensitive pathogens, and compounds 19 and 22 displayed significant improvement of activities against sensitive pathogens and two strains of MRSE, which verified the importance of desosamine in the interaction of macrolide and its receptor, and offered valuable information of the SAR of macrolide 4″-OH derivatives.     

HPLC测定葛花中6″-O-木糖鸢尾苷的含量

本文建立了葛花中6″-O-木糖鸢尾苷含量测定的HPLC方法。采用GRACE C18(250 mm×4.6 mm,5μm)色谱柱,流动相为乙腈-水梯度洗脱,流速为0.8 mL/min,紫外检测波长为265 nm,柱温为室温。6″-O-木糖鸢尾苷的峰面积(Y)与浓度(X)在10.33～185.99μg/mL范围内线性关系良好,Y=30731X–216635,r=0.9992(n=7);平均回收率为100.2%,RSD<2%(n=9);测得8批葛花药材中6″-O-木糖鸢尾苷含量为11.08～48.23 mg/g。方法学验证结果表明该法准确、可靠,可用于葛花中主要成分6″-O-木糖鸢尾苷的含量测定。     

Biotransformation of puerarin into puerarin-6″-O-phosphate by Bacillus cereus

The biotransformation of puerarin catalyzed by Bacillus cereus NT02 was studied. A primary screening was carried out using 307 strains of bacteria isolated from soil which were able to grow in the presence of puerarin. Strain NT02, identified as B. cereus, was able to convert puerarin into puerarin-6″-O-phosphate. Under the optimum conditions, resting cells of B. cereus NT02 converted 27% of added 0.4 g/l puerarin into puerarin-6″-O-phosphate that was characterized by MS, ¹³C NMR, ³¹P NMR. The activity of puerarin-6″-O-phosphate was 25 times higher than that of puerarin in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging system. The water solubility of puerarin-6″-O-phosphate was 85.4 times higher than that of puerarin.     

Isoorientin-6″-O-glucoside,a water-soluble antioxidant isolated from Gentiana arisanensis

The antioxidant activities of isoorientin-6″-O-glucoside were studied using various models. Isoorientin-6″-O-glucoside was more potent than Trolox, probucol and butylated hydroxytoluene (BHT) in reducing the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). It also scavenged superoxide anion, peroxyl and hydroxyl radicals that were generated by xanthine/xanthine oxidase, 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) and Fe³⁺–ascorbate–EDTA–H₂O₂ system, respectively. The IC₅₀ value, stoichiometry factor and second-order rate constant were 9.0 ± 0.8 μM, 1.8 ± 0.1 and 2.6 × 10¹⁰ M⁻¹ s⁻¹ for superoxide generation, peroxyl and hydroxyl radicals. However, isoorientin-6″-O-glucoside did not inhibit xanthine oxidase activity or scavenge hydrogen peroxide (H₂O₂), carbon radical or 2,2′-azobis(2,4-dimethylvaleronitrile) (AMVN)-derived peroxyl radical in hexane. Isoorientin-6″-O-glucoside inhibited Cu²⁺-induced oxidation of human low-density lipoprotein (LDL) as measured by fluorescence intensity, thiobarbituric acid-reactive substance formation and electrophoretic mobility. Since isoorientin-6″-O-glucoside did not possess pro-oxidant activity, it may be an effective water-soluble antioxidant that can prevent LDL against oxidation.     

Identification of 4″-isovaleryl-spiramycin III produced by Bacillus sp. fmbJ

The production of secondary metabolites with antibiotic properties is a common characteristic to Bacillus spp. These metabolites not only have diverse chemical structures but also have a wide range of bioactivities with medicinal and agricultural interests such as antibiotic. Bacillus sp. fmbJ has been found to produce lipopeptides fengycin and surfactin in accordance with our previous report. In this study, another antimicrobial substance was separated and purified from the culture supernatant of strain fmbJ using the silica gel column chromatography and preparative reversed-phase high-performance liquid chromatography. By means of electrospray ionization mass spectroscopy, infrared spectroscopy, and nuclear magnetic resonance, the antagonistic compound was determined to be 4″-isovaleryl-spiramycin III with the molecular weight of 982 Da. This report is the first to introduce the finding of spiramycin produced from Bacillus sp. The study provides a novel source for the production of spiramycin in pharmaceutical industries.     

6′-substituted and 6′,6″-disubstituted derivatives of raffinose

The reaction of 6′-chloro-6′-deoxyraffinose deca-acetate with a variety of nucleophilic anions (Br^-,I^-,N^-₃) gave the corresponding 6′-substituted raffinoses. The 6′-azide was further converted into 6′-amino-6′-deoxyraffinose, isolated as its N-acetyl derivative, and silver fluoride-induced elimination of hydrogen iodide from the 6′-iodide gave the 6′-deoxy-5′-ene. Treatment of 6′-chloro-6′-deoxyraffinose and 6′,6″-dichloro-6′,6″-dideoxyraffinose with base afforded, respectively, 3′,6′-anhydro-and 3′,6′;3″,6″-dianhydro-raffinose in high yields. In addition, the dichloride was converted into 6′,6″-diazido-6′,6″-dideoxyraffinose.     

Synthesis and Physicochemical Properties of 2′-Deoxy- 2′,2″-difluoro-β-D-ribofuranosyl and 2′-Deoxy-2′,2″- difluoro-α-D-ribofuranosyl Oligonucleotides

Abstract

We present procedures for nucleoside and oligonucleotide synthesis, binding affinity (T _m) and structural analysis (CD spectra) of 2′-deoxy-2′,2″-difluoro-α-D-ribofuranosyl and 2′-deoxy-2′,2″-difluoro-β-D-ribofuranosyl oligothymidylates. Possible reasons for the thermal instability of duplexes formed between these compounds and RNA or DNA targets are discussed.     

Aminoglycoside-3″-adenyltransferase confers resistance to spectinomycin and streptomycin in Nicotiana tabacum

The bacterial gene aad A encodes the enzyme aminoglycoside-3-adenyltransferase that confers resistance to spectinomycin and streptomycin in Escherichia coli. Chimeric genes have been constructed for expression in plants, and were introduced into Nicotiana tabacum by Agrobacterium binary transformation vectors. Spectinomycin or streptomycin in selective concentrations prevent greening of N. tabacum calli. Transgenic clones, however, formed green calli on selective media containing spectinomycin, streptomycin, or both drugs. Resistance was inherited as a dominant Mendelian trait in the seed progeny. Resistance conferred by the chimeric aad A gene can be used as a color marker similar to the resistance conferred by the streptomycin phosphotransferase gene to streptomycin.     

4″-异戊酰基转移酶基因重组质粒构建及其异源表达

目的:通过构建重组质粒,异源表达4＂-异戊酰基转移酶基因(4＂-isovaleyltrasferase gene,ist)生产螺旋霉素.方法:在螺旋霉素的4＂位加上异戊酰基侧链从而获得基因药物必特螺旋霉素基因.结果:研究表明acyB2基因是ist的正调控基因,ist基因与acyB2基因构建的ist-acyB2共表达质粒不能在变铅青链霉菌TK24中表达.启动区点突变的回复表明770bp到780bp之间有一碱基由原来的A回复成G.结论:经测序研究后发现在ist的启动区产生了一个点突变,拟回复此突变之后重新构建新的ist-acyB2载体,可用于检测ist基因在异源宿主中的表达情况.     

Second Generation Antisense Oligonucleotides—Inhibition of PKC-α and c-raf Kinase Expression by Chimeric Oligonucleotides Incorporating 6″-Substituted Carbocyclic Nucleosides and 2″-O-Ethylene Glycol Substituted Ribonucleosides

Abstract

6′-substituted carbocyclic deoxyribonucleosides and 2′-O-ethylene glycol substituted ribonucleosides have been evaluated as building blocks for antisense oligonucleotides. Within the former class 6′-hydroxy substituted building blocks in combination with internucleoside phosphorothioate linkages have the potential to enhance antisense activity. 2′-O-ethylene glycol substituted ribonucleosides generally allow for the construction of potent antisense oligonucleotides with reduced phosphorothioate content, but differences exist in their effects on biological activity in cell culture in spite of virtually identical effects on RNA-binding affinity. Activity enhancement was most pronounced for a 2′-O-methoxyethyl substituent.