Aqueous Aza-Michael Reaction of Conjugated Alkenes: Toward Spermine

An aqueous aza-Michael reaction is efficiently achieved with excellent conversions without any additives. The method works very well on a molar scale with selectively for aliphatic amines. An intermediate for spermine is also made by this green process.     

Synthesis of Cucurbituril-spermine-[2]rotaxanes of the Amide-type

Abstract

[2]Rotaxanes with the macrocyclic ligand cucurbituril were prepared in yields between 10 and 90% from the reaction of the spermine complex with cucurbituril and different carboxylic acid chlorides in a two phase Schotten-Baumann reaction. This reaction type offers the possibility to synthesize a lot of different [2]rotaxanes. They are characterised by elemental analysis, ¹H-NMR spectroscopy and mass spectrometry.     

共振光散射法研究脱氧核糖核酸与多胺的相互作用及精胺的测定

在一定条件下,精胺不仅能够与脱氧核糖核酸(DNA)大沟嵌入结合,还能与DNA链上的碱基和磷酸基进行链内结合和跨链结合,形成致密的环状螺旋结构,造成DNA的凝聚,从而使DNA共振光散射(RLS)强度强烈地增强。增强的共振光散射强度与精胺的浓度呈现良好的线性关系,线性范围为5.0×10-7~1.0×10-5mol/L;校正曲线的回归方程为IRLS=40.22 5.28×107C(mol/L),相关系数r=0.9936;检出限(3σ)为7.4×10-8mol/L。在测定精胺的线性范围内,其它多胺(亚精胺,腐胺)、蛋白质及常见的金属离子不干扰测定。该方法用于测定新几内亚凤仙中的精胺,获得满意结果。     

Prediction of microscopic protonation constants of polybasic molecules via computational methods: A complete microequilibrium analysis of spermine

For the first time, a simple methodology is reported for theoretical calculation of microscopic protonation constants of polybasic molecules in solution. Density functional theory study was used for complete microequilibrium analysis of spermine, H₂N(CH₂)₃NH(CH₂)₄NH(CH₂)₃NH₂, a linear tetraamine with 16 known microspecies. A general thermodynamic cycle is proposed to calculate protonation microconstants of polybasic molecules using calculated micro‐ΔG values in aqueous solution. The microscopic protonation constants were determined with considering both the most abundant and most stable conformers for all microspecies. The results show that the microscopic protonation constants derived from the most abundant conformers (i.e., linear conformers in which the intramolecular hydrogen bonding does not exist) are in good agreement with the corresponding available experimental data. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Increased Affinity of 2′‐O‐(2‐Methoxyethyl)‐Modified Oligonucleotides to RNA through Conjugation of Spermine at Cytidines

Structural modification at the 2′‐O‐position of riboses in oligonucleotide therapeutics is of critical importance for their use as drugs. To date, the methoxyethyl (MOE) substituent is the most important and features in dozens of antisense oligonucleotides that have been tested in clinical trials. Yet, the search for new improved modifications continues in a quest for increased oligonucleotide potency, improved transport in vivo and favorable metabolism. Recently, we described how the conjugation of spermine groups to pyrimidines in oligonucleotides vastly increases their affinity for complementary RNAs through accelerated binding kinetics. Here we describe how spermines can be linked to the exocyclic amino groups of cytidines in MOE‐oligonucleotides employing a straightforward ‘convertible nucleoside approach’ during solid phase synthesis. Singly‐ or doubly‐modified oligonucleotides show greatly enhanced affinity for complementary RNA, with potential for a new generation of MOE‐based oligonucleotide drugs.     

Overview on natural hydrophilic polysaccharide polymers in drug delivery

Nanotechnology is poised to make potentially revolutionary innovations in areas of biomedical science, such as gene therapy and drug therapy. A recently developed nanodelivery strategy involves the use of hydrophilic polymers as carriers of proteins and siRNA. By controlling the reaction conditions during polymer production, various degrees of anionic charge, cationic charge, and cross‐linking can be added, thereby changing their capabilities as protein and nucleic acid carriers and promoting effective cell membrane permeation. The efficiency of a specific controlled‐release polymeric system is determined in part by its unique physical and chemical properties and biodegradation rate. In this review, we will summarize recent progress in the ability to modify drug release of hydrophilic polymers nanoparticles.     

Spermine‐Functionalized Perylene Bisimide Dyes—Highly Fluorescent Bola‐Amphiphiles in Water

A series of four spermine‐functionalized perylene bisimide dyes without linkers ( 1 ) and with linkers ( 2 – 4 ) between the chromophore and the polyamine was synthesized. Protonation of the spermine moieties resulted in the formation of highly water‐soluble dyes with up to six positively charged ammonium ions. The aggregation behavior of these strongly fluorescent bola‐amphiphiles was studied in pure water as solvent by UV/Vis and fluorescence spectroscopy, and an astonishingly high fluorescence quantum yield of up to Φ_fl=0.90 was observed for PBI 1 . Atomic force microscopy and transmission electron microscopy were applied for the visualization of the aggregates on surfaces. Molecular modeling studies were performed by force‐field calculations to explore the aggregate morphologies, which also provided valuable information on the influence of the additional alkylcarbonyl linkers. Our detailed spectroscopic and microscopic investigations revealed that the excellent optical properties of perylene bisimide chromophores can be used even in pure deionized water if their aggregation is efficiently suppressed.     

离子色谱法同时测定水源水中的5种生物胺

建立了离子色谱(IC)同时测定水源水中5种生物胺(BA)(腐胺、尸胺、组胺、亚精胺和精胺)的方法。样品经0.45 μm水膜过滤后,用TSK-GEL SuperIC阳离子交换柱(150 mm×4.6 mm)分离,以甲磺酸水溶液为流动相梯度淋洗,流速为1.0 mL/min,非抑制电导检测,进样量为100 μL。实验结果表明,5种生物胺可以实现基线分离;在1.0～30.0 mg/L范围内,其峰面积与质量浓度之间的线性关系良好;保留时间的相对标准偏差(RSD)均不高于0.02%,峰面积的RSD小于2.08%;加标回收率为96.0%～107.0%。该法简便、快捷、准确,可以用于水源水中腐胺、尸胺、组胺、亚精胺和精胺5种生物胺的同时测定。     

Structure, Stability, Electronic Properties and NMR-Shielding of the Cucurbit[6]uril–Spermine-Complex

Geometries, stabilities, electronic properties and NMR-shielding of cucurbit[6]uril–spermine host-ligand complexes are investigated with DFT calculations and compared to experimental results. Cucurbit[6]uril and spermine can form complexes with two different minimum energy geometries and corresponding characteristic differences in NMR shielding. The energetically preferred complex geometry has a perfect inversion symmetry and its proton NMR shielding agrees very well with experimental results. The cucurbit[6]uril host molecule shows a distinct geometrical flexibility in ligand binding which allows an induced fit of the spermine ligand. The energetic barrier for the rotation of spermine in the favourable complex is approximated to be in the order of a few kilocalories per mole.     

Electrochemical sensing platform based on the use of ZnONPs and MWCNTs as CPE modifiers for a selective and sensitive determination of polyamine spermine in the urine sample

A simple electroanalytical procedure has been developed for the determination of polyamine spermine using the ZnONPs-MWCNTs-CPE sensor. Spermine has been irreversibly oxidized on a modified electrode at a potential of +0.92 V versus Ag/AgCl (KCl, 3.5 mol L⁻¹). The developed sensor demonstrated a respective linear response in borate buffer pH 8.5 from 2 μmol L⁻¹ to 100 μmol L⁻¹, with a detection limit of 0.300 μmol L⁻¹ and quantification limit of 0.998 μmol L⁻¹. The proposed sensor showed high reproducibility (RSD = 2.58 %), stability, robustness, and no obvious interference effects of several inorganic ions and organic molecules. The obtained results demonstrated excellent performance during the determination of the spermine in human urine samples with satisfactory recovery results (98.41–101.34 %), offering promising opportunities for practical clinical analysis.