New micro-flow pumping system for liquid chromatography

This paper deals with the development of practical approaches to a new liquid-delivery system for capillary liquid chromatography. Under different chromatographic conditions, the factors affecting liquid-delivery performance are theoretically described, and the new liquid-delivery system without any splitter is evaluated with its flow-rate accuracy and precision using a variety of solvents. The experimental results demonstrate that the liquid-delivery system is capable of generating accurate, reproducible and conditions-independent micro- and nano-flows.     

Mannich-type reaction with trifluoromethylated N,O-hemiacetal: facile preparation of beta-amino-beta-trifluoromethyl carbonyl compounds

On treatment of silyl enolates and an N,O-hemiacetal, derived from trifluoroacetaldehyde ethyl hemiacetal and p-anisidine, with GaCl(3) (0.2 equiv) and C(6)H(5)COCl (0.2 equiv) in propionitrile, Mannich-type reaction took place smoothly to afford beta-amino-beta-trifluoromethyl carbonyl compounds in high yields.     

Structural alteration of hybrid supramolecular capsule induced by guest encapsulation

Heterofunctionalized C(2v) symmetrical cavitand 1 with 4-pyridylethynyl and 3-carbamoylphenyl groups in alternating arrangement was designed and synthesized. A 1:1 mixture of the cavitand 1 and a cis-coordinated palladium(II) or platinum(II) complex self-assembled into a hybrid supramolecular capsule via both metal-ligand coordination bonds and hydrogen bonds. Formation of the capsular assembly was confirmed by NMR spectroscopy and mass spectrometry. The hybrid capsule encapsulated the appropriate guest, the molecular sizes of which fit the size of the capsular cavity. Structural alteration of the hybrid capsule was induced by the guest encapsulation. A C(2h) structure for the encapsulation complex was assigned by 2D NMR spectra analysis. Thermodynamic and kinetic properties of the guest encapsulation were investigated. The kinetics of in/out guest exchange was strongly influenced by hydrogen bonding in the hybrid capsule.     

Cryogenic plasmas for controlled processing of nanoporous materials

Plasma processing at cryogenic temperatures tremendously suppresses the depth penetration of plasma radical species within nanoporous materials. We demonstrate that this confining effect is surprisingly unrelated to changes in the phase diffusivity of radical species gas, but is determined by the increase of the sticking coefficient and the radical recombination and reaction factors, favoring an early irreversible surface adsorption of the plasma radical species.     

Chiral supramolecular thiophene fluorophore consisting of thiophenecarboxylic acid derivatives

Solid-state chiral supramolecular thiophene fluorophore has been successfully prepared by using chiral (R)-1-(2-naphthyl)ethylamine and 5-bromothiophene-2-carboxylic acid. This chiral supramolecular thiophene fluorophore is formed by assembling chiral 2₁-helical columnar network structures composed of (R)-1-(2-naphthyl)ethylamine and 5-bromothiophene-2-carboxylic acid. This supramolecular organic fluorophore exhibits circularly polarized luminescence (CPL) even in the solid state.     

Enhanced transdermal delivery of indomethacin-loaded PLGA nanoparticles by iontophoresis

Nanoparticles effectively deliver therapeutic agent by penetrating into the skin. Indomethacin (IM) and coumarin-6 were loaded in PLGA nanoparticles with an average diameter of 100 nm. IM and coumarin-6 were chosen as a model drug and as a fluorescent marker, respectively. The surfaces of the nanoparticles were negatively charged. Permeability of IM-loaded PLGA nanoparticles through rat skin was studied. Higher amount of IM was delivered through skin when IM was loaded in nanoparticles than IM was free molecules. Also, iontophoresis was applied to enhance the permeability of nanoparticles. When iontophoresis with 3 V/cm was applied, permeability of IM was much higher than that obtained by simple diffusion of nanoparticles through skin. The combination of charged nanoparticle system with iontophoresis is useful for effective transdermal delivery of therapeutic agents.     

Total synthesis and biological assessment of (-)-exiguolide and analogues

We describe herein an enantioselective total synthesis of (-)-exiguolide, the natural enantiomer. The methylene bis(tetrahydropyran) substructure was efficiently synthesized by exploiting olefin cross-metathesis for the assembly of readily available acyclic segments and intramolecular oxa-conjugate cyclization and reductive etherification for the formation of the tetrahydropyran rings. The 20-membered macrocyclic framework was constructed in an efficient manner by means of Julia-Kocienski coupling and Yamaguchi macrolactonization. Finally, the (E,Z,E)-triene side chain was introduced stereoselectively via Suzuki-Miyaura coupling to complete the total synthesis. Assessment of the growth inhibitory activity of synthetic (-)-exiguolide against a panel of human cancer cell lines elucidated for the first time that this natural product is an effective antiproliferative agent against the NCI-H460 human lung large cell carcinoma and the A549 human lung adenocarcinoma cell lines. Moreover, we have investigated structure-activity relationships of (-)-exiguolide, which elucidated that the C5-methoxycarbonylmethylidene group and the length of the side chain are important for the potent activity.     

A novel, bio-reducible gene vector containing arginine and histidine enhances gene transfection and expression of plasmid DNA

We have engineered a novel, non-viral, multifunctional gene vector (STR-CH(2)R(4)H(2)C) that contained stearoyl (STR) and a block peptide consisting of Cys (C), His (H), and Arg (R). STR-CH(2)R(4)H(2)C can form a stable nano-complex with plasmid DNA (pDNA) based on electronic interactions and disulfide cross linkages. In this study, we evaluated the efficacy of STR-CH(2)R(4)H(2)C as a gene vector. We first determined the optimal weight ratio for STR-CH(2)R(4)H(2)C/pDNA complexes. The complexes with a weight ratio of 50 showed the highest transfection efficacy. We also examined the transfection efficacy of STR-CH(2)R(4)H(2)C/pDNA complexes with or without serum and compared STR-CH(2)R(4)H(2)C/pDNA transfection efficacy with that of Lipofectamine. Even in the presence of serum, STR-CH(2)R(4)H(2)C showed higher transfection efficacy than did Lipofectamine. In addition, we determined the mechanism of transfection of the STR-CH(2)R(4)H(2)C/pDNA complexes using various cellular uptake inhibitors and evaluated its endosomal escape ability using chloroquine. Macropinocytosis was main cellular uptake pathway of STR-CH(2)R(4)H(2)C/pDNA complexes. Our results suggested that STR-CH(2)R(4)H(2)C is a promising gene delivery system.     

Synthesis and matrix metalloproteinase-12 inhibitory activity of ageladine A analogs

Synthesis of the 37 ageladine A analogs was accomplished by employing the total synthetic route of natural ageladine A previously explored by us. From the matrix metalloproteinase-12 (MMP-12) inhibitory activity assay carried out using the novel analogs, it appeared evident that the halogen atom at the 2-position of pyrrole ring was essential for the inhibitory activity and that the introduction of a bromine atom into the 4-position of pyrrole ring is very effective for producing potent activity. In addition, exchange of the pyrrole ring to an imidazole ring was extremely effective in increasing activity, and the analog 29 thus obtained was found to show approximately 4 times more potent activity than natural ageladine A.