Tween 20-stabilized gold nanoparticles combined with adenosine triphosphate-BODIPY conjugates for the fluorescence detection of adenosine with more than 1000-fold selectivity

This study describes the development of a simple, enzyme-free, label-free, sensitive, and selective system for detecting adenosine based on the use of Tween 20-stabilized gold nanoparticles (Tween 20-AuNPs) as an efficient fluorescence quencher for boron dipyrromethene-conjugated adenosine 5′-triphosphate (BODIPY-ATP) and as a recognition element for adenosine. BODIPY-ATP can interact with Tween 20-AuNPs through the coordination between the adenine group of BODIPY-ATP and Au atoms on the NP surface, thereby causing the fluorescence quenching of BODIPY-ATP through the nanometal surface energy transfer (NSET) effect. When adenosine attaches to the NP surface, the attached adenosine exhibits additional electrostatic attraction to BODIPY-ATP. As a result, the presence of adenosine enhances the efficiency of AuNPs in fluorescence quenching of BODIPY-ATP. The AuNP-induced fluorescence quenching of BODIPY-ATP progressively increased with an increase in the concentration of adenosine; the detection limit at a signal-to-noise ratio of 3 for adenosine was determined to be 60 nM. The selectivity of the proposed system was more than 1000-fold for adenosine over any adenosine analogs and other nucleotides. The proposed system combined with a phenylboronic acid-containing column was successfully applied to the determination of adenosine in urine.     

核酸识体的研究及应用

核酸识体(aptamer)是近年来发展起来的一类经体外人工进化程序筛选出的寡聚核苷酸。它能高效、特异地结合各种配体，在蛋白质的分析检测、医学诊断治疗、生物传感器和分子开关的开发等方面有很大的应用前景，文章对核酸识体的研究和应用进展进行了综述。     

Metabolomic-based investigation of Yinlan alleviating hyperlipidemia by inhibiting blood stasis and phlegm turbidity through the PXR-CYP3A4-ABCB1-FXR pathway

Yinlan lipid regulatory capsule (YL) is a composite traditional Chinese medicine (TCM) new drug to alleviate hyperlipidemia, while its therapeutic mechanism in vivo was not clarified with nontargeted metabolomics investigation. An animal model was established in rats fed a high-fat diet, and their body weights, body mass index (BMI) and blood cholesterol levels were measured. Serum, liver and kidney tissue samples were also extracted for PXR-CYP3A4-ABCB1-FXR signaling pathway research using PCR and UHPLC–MS. The obtained plasma samples were analyzed by UHPLC-Q-TOF-MS metabolomic investigation, which revealed PXR-CYP3A4-related metabolites and changes induced by YL. Finally, the key metabolites were chosen as index components, and their levels in the serum, liver, small intestine and bile were used for simultaneous UHPLC–MS-MS determination. The results indicated that YL was effective in rebalancing blood TG and TC levels (compared to controls). With respect to the PXR-CYP3A4-ABCB1 pathway, as a result of YL’s effect, gene expression or activity of the two targets decreased significantly in both the liver and kidney. The same trend was observed in the serum samples mentioned above. Metabolomics screening and data revealed that 44 metabolites can be regarded as biomarkers related to hyperlipidemia, fatty acids synthesis, and body energy consumption, as well as synthesis, transportation and exertion of cholesterol. YL’s treatment focused on 26 of them, primarily bile acids, indicating that the antihyperlipidemic effect of this drug lies in its inhibitory activity of cholesterol metabolism. Subsequent analysis of those in vivo components revealed that significant increases (compared to the model group) occurred in the blood, liver, small intestine and bile in groups that received medium and high doses of YL (while the low dose was relatively unchanged). Those target components exhibit a close relationship with PXR and/or CYP3A4. The use of YL repressed PXR expression and subsequently decreased CYP3A4 activity. As a result, synthesis of related bile acids increased, while cholesterol levels decreased, consequently leading to the attenuation of hyperlipidemia. This study comprehensively investigated the antihyperlipidemia mechanism of YL based on its repression of PXR-CYP3A4 activity and related metabolite yield, establishing an accurate method for evaluating the therapeutic effect of YL.     

Active Chemical Constituents from Sauropus androgynus

This paper describes the chemical investigation on BuOH-soluble EtOH extract from the aerial part of Sauropus androgynus. This study led to the characterization of six bioactive ingredients including three nucleosides—adenosine (1), 5′-deoxy-5′-methylsulphinyl-adenosine ( 2 ), and uridine ( 3 ), two flavonol dioside — 3-O-β-D-glucosyl-7-O-α-L-rhamnosyl-kaempferol ( 4 ), 3-O-β-D-glucosyl-(1→6)-β-D-glucosyl-kaempferol ( 5 ), and one rare flavonol trioside — 3-O-β-D-glucosyl-(1→6)-β-D-glucosyl-7-O-α-L-rhamno-syl-kaempferol ( 6 ). Their structures were determined on the basis of spectral analysis.     

高效液相色谱法测定蛹虫草中腺苷和虫草素

在蛹虫草中腺苷和虫草素含量的反相高效液相色谱分析中,所用色谱柱为WatersNOVA-PAK C18(3.9 mm×300 mm,4μm),流动相为0.01 mol.L-1KH2PO4-K2HPO4缓冲溶液(pH 6.86)+1%(体积分数)四氢呋喃,流速为1.0 mL.min-1。紫外检测的波长为260 nm,峰面积与腺苷浓度和虫草素浓度之间的线性范围依次为1.27~50.5 mg.L-1和3.23~129.0 mg.L-1,其检出限依次为0.18 ng和0.25 ng。在腺苷及虫草素的浓度水平依次为5.05 mg.L-1和12.9 mg.L-1时测试方法的精密度,求算得RSD(n=7)值依次为0.094%和0.792%。用标准加入法试验方法的回收率,求得两者的平均回收率依次为103.2%和98.5%。     

Capillary electrophoresis as a tool for screening aptamer with high affinity and high specificity to ricin

Aptamers which specifically recognize targets are selected from random oligonucleotide library using systematic evolution of ligands by exponential enrichment (SELEX). In this paper, capillary electrophoresis (CE) as a separation approach has been introduced to SELEX procedure. The high efficiency of CE gives rise to greatly shorten the selection procedure. The results from enzyme-linked assay and dot blot experiment show that an enrichment pool has been obtained after four rounds selection, which can specifically recognize ricin. __________ Translated from Chemical Journal of Chinese Universities, 2006, 27(10): 1,840–1,843 [译自: 高等学校化学学报]     

Synthesis of new pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines and related heterocycles

The reaction between 5-amino-4-imino-1(2)-substituted-1(2)H-4,5-dihydropyrazolo[3,4-d]pyrimidines and several commercially available reactants afforded new heterocycles with a conserved pyrazolo[3,4-d]pyrimidine nucleus. The key intermediates employed proved to be suitable compounds by virtue of their two vicinal amino and imino groups that were used to obtain five, six and seven-membered rings.     

Nucleosides 4: Synthesis of 2′,3′-Didehydro-2′,3′-dideoxydoridosine and 2′,3′-Dideoxydoridosine as Potential Antihypertensive Agents

To measure the hydrophobic character of the ribose moiety of doridosine on the adenosine receptors, 2′,3′-didehydro-2′,3′-dideoxydoridosine (2) and 2′,3′-dideoxydoridosine (3) were prepared. Initial treatment of doridosine with N,N-dimethylformamide diethylacetal, and subsequently with tert-butyldimethylsilyl chloride gave 5. Compound 5 was then reacted with 1,1′-thiocarbonyldiimidazole and the resulting thionocarbonate 6 was heated with triethyl phosphite at 135°C to afford 7. Treatment of compound 7 with tetrabutylammonium fluoride and methanolic ammonia furnished compound 2 in good yield. Compound 2 was subjected to catalytic hydrogenation affording compound 3 in 85% yield.     

化学位移估算研究ATP构象随溶液pH值的变化

利用Johnson和Bovey的理论和方法计算了不同扭曲角χ(O4′－C1′－N9－C4)的ATP(5′-三磷酸腺苷)分子中糖环质子H1′和H2′由于环流效应引起的化学位移.H1′的化学位移与扭曲角χ有较强的依赖关系,反映了ATP在溶液中细微的构象变化.将计算结果与实验结果比较,证明在本文讨论的pH值范围(1～10)内,Mg2＋加入后,ATP的扭曲角χ在230～360°范围内变化.随溶液的pH值减小,ATP分子的构象由trans 构象通过-gauche构象转变为cis构象. 从而证明在酸性条件下, ATP倾向于以cis构象存在,而在碱性条件下trans构象更为稳定,从另一方面支持了在酸性条件下N1参与配位而在碱性条件下N7参与配位的结论.在讨论中也考虑了由pH变化所引起的环流强度的变化.     

Validation of an empirical RNA-ligand scoring function for fast flexible docking using RiboDock®

We report the design and validation of a fast empirical function for scoring RNA-ligand interactions, and describe its implementation within RiboDock, a virtual screening system for automated flexible docking. Building on well-known protein-ligand scoring function foundations, features were added to describe the interactions of common RNA-binding functional groups that were not handled adequately by conventional terms, to disfavour non-complementary polar contacts, and to control non-specific charged interactions. The results of validation experiments against known structures of RNA-ligand complexes compare favourably with previously reported methods. Binding modes were well predicted in most cases and good discrimination was achieved between native and non-native ligands for each binding site, and between native and non-native binding sites for each ligand. Further evidence of the ability of the method to identify true RNA binders is provided by compound selection ('enrichment factor') experiments based around a series of HIV-1 TAR RNA-binding ligands. Significant enrichment in true binders was achieved amongst high scoring docking hits, even when selection was from a library of structurally related, positively charged molecules. Coupled with a semi-automated cavity detection algorithm for identification of putative ligand binding sites, also described here, the method is suitable for the screening of very large databases of molecules against RNA and RNA-protein interfaces, such as those presented by the bacterial ribosome.