Effects of Processing Variables on the Morphology and Diameter of Electrospun Poly(amino acid ester)phosphazene Nanofibers

Poly[（alanino ethyl ester）0.67 （glycino ethyl ester）0.33 phosphazene] （PAGP） was synthesized, and morphology and diameter of the electrospun PAGP nanofibers were systematically evaluated by using a cool field emission scanning electron microscope （SEM） with changing the important processing variables such as applied voltage, polymeric concentration, and ambient temperature. The average diameter of PAGP nanofibers was inversely proportional to the applied voltage, but increased with the increase of solution concentration. Lower environmental temperature was unfavorable due to the nanofibers conglutination.

STUDIES ON THE SYNTHESIS AND ANTITUMOR ACTIVITY OF AMINO ACID ESTER DERIVATIVES OF BENZISOSELENAZOLONE

This paper reports a simple method for the synthesis of amino acid ester derivatives of benzisoselenazolone.Their anticancer activity is also given.

Synthesis of Macrocycles Containing Amino Acid Ester and Aryl-heterocyclic Units

Four kinds of new macrocycles containing amino acids and nyl-heterocyclic units were synthesized by the condensation of di-esters containing Ts-amino acids units with di-halogenated compounds at room temperature. The macrocycles were characterized by elemental analysis, IR,MS(FAB) and 1H NMR

Catalytic Hydrolysis of Lipophilic Amino Acid Esters by Metallomicelles as Carboxypeptidase A Models

Lipophilic complexes of macrocyclic 12-membered dioxotetraamine ligand bearing bis-hydroxy groups as functional pendants are effective catalysts for the hydrolysis of amino acid esters in micellar media, and the rate enhancement of more than 10-fold were observed.

Efficient synthesis of thiohydantoin derivatives from amino acid esters and isothiocyanates in alkaline Al_2O_3

Various amino acid esters were reacted with different isothiocyanates in alkaline Al2O3 at room temperature for 1 h affording thiohydantoins in moderate to excellent yields.

Exploring Ester Prodrugs: A Comprehensive Review of Approaches, Applications, and Methods

The review provides an overview of the approaches, applications, and methods for ester prodrugs. Ester prodrugs are pharmacologically inactive compounds in their original form but become active drugs on biotransformation within the body, which offers advantages concerning the solubility, stability, and targeted delivery of the active drug. Several approaches of ester prodrugs have been reviewed in this review, including simple ester prodrugs, amino acid ester prodrugs, sugar ester prodrugs, lipid ester prodrugs, and polymeric ester prodrugs. This review incorporates in vitro and in vivo methods as well as the characterization of physical and chemical properties for ester prodrugs, cell culture systems, enzymatic assays, and animal models—all of these having a very important bearing on the evaluation of stability, bioavailability, and efficacy for ester prodrugs. While the benefits of using ester prodrugs are significant, there are also disadvantages like instability, poor or variable enzymatic hydrolysis, and toxicity from released promoieties or by-products. This review discusses solutions to the various limitations that include enhancing stability with ionizable promoieties and using physiologically-based pharmacokinetic modeling. The review also highlights the application of ester prodrugs in neurological disorders, such as Parkinson’s disease, and the ongoing efforts to address the critical limitations in treatment efficacy. Future prodrug strategies are poised to advance significantly by harnessing diverse transport mechanisms across the blood-brain barrier and integrating nanotechnology.

NMR Studies of a New Binding Mode of the Amino Acid Esters by Porphyrinatozinc(Ⅱ)

The binding mode of the amino acid ethyl esters(guest) by 5 (2 carboxylphenyl) 10,15,20 triphenylporphyrinatozinc(Ⅱ)(host 1) was studied by means of 1H NMR spectra. The binding mode is the hydrogen bonding between the amino group of the guest and the carboxyl group of host 1 plus the coordination between the zinc atom of porphyrinatozinc(Ⅱ) and the carbonyl group of the guest. This is a novel binding mode of the metalloporphyrin to amino acid derivatives.

Absolute Configurational Assignments of Amino Acid Esters by a CD-Sensitive Malonamide-Linked Zinc Bisporphyrinate Host

A novel malonamide-linked zinc bisporphyrinate[Zn_(2)-1]has been designed and synthesized.UV-vis and NMR spectroscopic studies suggest the molecule aggregates in solution.Such zinc bisporphyrinate is very CD-sensitive when it is mixed with amino acid ethyl esters.The amplitude value of the induced circular dichroism(ICD)is up to ca.1500 L•mol^(−1)•cm^(−1).Further studies by ^(1)H NMR and UV-vis spectroscopies reveal amino acid esters function as monodentate ligands,and[Zn_(2)-1]interacts with amino acid ethyl esters through coordination and hydrogen bonding interactions.

Synthesis and antitumor activity of novel 10-amino acids ester homocamptothecin analogues

Nine racemic homocamptothecin derivatives were synthesized and in vitro antitumor activities were evaluated by standard MTT method. The results showed that some of the compound had higher antitumor activity than iritecan.

Pyrolysis-GC/MS of Menthyl Esters of N-Benzoxycarbonyl Amino Acid

With the aid of a Pyrolysis-GC/TOF MS technique, the pyrolysis behaviour of two menthyl esters of N-benzoxycarbonyl amino acid was investigated. A clear pattern emerges involving the cleavage of the bond linking the menthyl ring to the carboxy group, followed by further degradation of the fragments. The major pyroproducts were p-menth-l-ene pyrolysed at a higher temperature or p-menth-2-ene pyrolysed at a lower temperature, and various derivatives of cyclohexene pyrolyzed from the menthyl ring. In addition, some of the products were also iden- tified as derivatives of benzene from the pyrolysis of benzyloxyl moiety.

Electrospray Ionization Mass Spectra of Amino Acid Methyl Ester 5′-Phosphoramidates of 2′,3′-Isopropylideneuridine

Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode dectrospmy ionization mass spectrometry（ESIMS） in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct.

Novel Phosphonoacetic Acid Derivatives.Synthesis of N-(Ethoxycarbonylmethylphosphonyl)-α-Amino Esters and-α-Amino Phosphonic Acid Esters and Their Bioactivities

A series of novel phosphonoacetic acid derivatives, N-(ethoxycarbonylmethy-ethoxyphosphonyl)-α-amino acid esters and α-amino phosphonates, were synthesized via the reaction of the corresponding phosphonyl chloride with amino acid ester hydrochlorides or amino phosphonates in the presence of a base. The preliminary bioassay shows that some compounds show significant anti-viral activity against tobacco mosaic virus (TMV)

A NEW ONE-STEP REDUCTIVE N-ALKYLATION OF AMINO ACIDS AND THEIR ESTERS

The reductive alkylation of amine with carbonyl compounds using sodium hydrogen telluride has been investigated in recent years. Application of this method to the synthesis of N-alkyl derivatives of biologically important amino acids and their esters is described.

Microwave-Assisted Facile and Rapid Esterification of Amino Acids I: Esterification of L-Leucine from Batch to Flow Processes and Scale-Up

We herein report our studies into the effects of microwave irradiation on the solvent-free esterification of L-leucine with alcohols. In the absence of solvent, microwave irradiation accelerated the reaction compared to conventional oil bath heating. Measurement of the dielectric properties under the reaction conditions revealed that the high dielectric loss factor of the reaction mixture containing L-leucine, n-butanol, and a p-toluene sulfonic acid catalyst could be attributed to the acceleration of the reaction. The depth of microwave penetration into the reaction mixture as derived from the in-situ measurement of the dielectric properties was ~13 mm, which suggested that a thinner reaction vessel was favorable for the esterification of L-leucine. In addition to the batch reaction using a desktop microwave reactor, two types of flow reaction were also performed using a desktop tubular reactor and a semi-bench-scale tubular reactor. These flow reactions also exhibited high performances, thus allowing the scale-up of this reaction system for industrial use.

The Synthesis of Cyclic Amino Acids

Several cyclic amino acids (1-4) were synthesized from glycine. Isocyanate ester was prepared as the key intermediate and reacted with dibromoalkanes to afford the target compounds.

The Synthesis of Some Novel N-[α-(Isoflavone-7-O-) Acetyl]Amino Acid Derivatives

A series of novel N-[α-(isoflavone-7-O-)acetyl] amino acid methyl esters were prepared from the efficient and regioselective alkylation of isoflavones with chloroacetyl amino acid derivatives under mild condition.

Preparation and Surfactant Properties of Amino Acid-based Surfactants

1-O-aminoacyl-3-O-alkyl acyl glycerols were synthesized by lipases in good yields and their surfactant properties were explored.

Highly efficient synthesis of β-amino esters via Mannich-type reaction under solvent-free conditions using ZnCl_2 catalyst

β-Amino esters were synthesized via ZnCl2-catalyzed Mannich-type reaction of imines and malonate esters under solvent-free conditions in 6 min. The β-amino ester was converted into the corresponding aspartic acid derivatives.

熊果酸及其氨基酸酯前体药物在大鼠体内的药动学研究

目的 建立测定大鼠血浆中熊果酸浓度的超高效液相色谱串联质谱(UPLC-MS/MS)分析方法,探讨熊果酸及其氨基酸酯前体药物在大鼠体内的药动学变化。方法 取雄性大鼠,经口给药70 mg·kg^(-1)(以熊果酸含量计)的熊果酸原料药,熊果酸-维生素E琥珀酸聚乙二醇酯混合液,熊果酸苯丙氨酸肌氨酸酯盐酸盐-维生素E琥珀酸聚乙二醇酯溶液。采用沉淀蛋白法处理血浆样品,以塞来昔布作为内标,色谱柱为Acquity UPLC~? BEH C18(50 mm×2.1 mm, 1.7μm)柱,流动相为体积分数0.025%氨水乙腈-10 mmol·L^(-1)乙酸铵-体积分数0.1%氨水溶液(体积比70∶30),流速0.4 mL·min^(-1),采用大气压化学电离源,负离子多反应监测模式扫描。结果 血浆中熊果酸在质量浓度100~10 000μg·L^(-1)内线性良好。与原料药比较,熊果酸-维生素E琥珀酸聚乙二醇酯混合液组和熊果酸苯丙氨酸肌氨酸酯盐酸盐-维生素E琥珀酸聚乙二醇酯溶液组的熊果酸生物利用度分别提高了8.43倍和19.52倍(P<0.05)。结论 经口给药后熊果酸在大鼠体内的生物利用度较低,前体药物熊果酸苯丙氨酸肌氨酸酯可提高熊果酸的经口给药生物利用度。分析方法符合生物样品的测定要求,适用于大鼠血浆中熊果酸质量浓度的测定。

基于聚谷氨酸聚氨基酯的核酸递送载体构建

核酸疫苗已成为现代传染病疫苗中的研究热点,然而,核酸疫苗的临床转化仍然面临着转染效率低下和生物相容性不佳等瓶颈,迫切需要研发安全、高效的核酸递送载体。本研究提出一种新的核酸递送策略,在聚(β-氨基酯)[poly(β-amino ester),PBAE]和核酸自组装形成PBAE纳米颗粒(PBAE nanoparticles,PBAE-NPs)的基础上,进一步采用聚谷氨酸[poly(glutamic acid),PGA]进行修饰,形成PGA修饰的PBAE纳米颗粒(PGA modified PBAE nanoparticles,PPs)。本文将通过结构表征和生物学评价探究PPs作为核酸递送载体的性能。体外表征结果显示,PPs具有粒径小、Zeta电位低和血清稳定性强等良好的生物学特性。细胞溶酶体逃逸实验结果表明,PGA修饰能够提高PPs的溶酶体逃逸能力。流式细胞术结果表明,相较于PBAE-NPs,PPs显著增强了核酸转染效率。此外,CCK-8实验结果显示,PPs具有良好的生物安全性。综上所述,PPs具有安全性好、核酸转染效率高等特点,是一种具有开发前景的核酸递送载体,为今后核酸疫苗载体的设计提供了新的思路。