Encapsulated molecular catalysts in polysiloxane gels: ruthenium cluster-catalyzed isomerization of alkenes

Novel ruthenium-encapsulating polysiloxane gels are prepared by treatment of polymethylhydrosiloxane with diols in the presence of (mu(3),eta(2),eta(3),eta(5)-acenaphthylene)Ru(3)(CO)(7), and act as reusable catalysts in the isomerization of alkenes without leakage of the catalyst species.     

Correlation between surface tension and void fraction in ionic liquids

An effort to systematize published and new data on the surface tension gamma of ionic liquids (ILs) is based on the hypothesis that the dimensionless surface tension parameter gamma V v (2/3)/ kT is a function of the void fraction x v = V v/ V m. The void volume V v is defined as the difference between the liquid volume V m occupied by an ion pair (known from cationic and anionic masses and liquid density measurements) and the sum V (+) + V (-) of the cationic and anionic volumes (known from crystal structures), while kT is the thermal energy. Our hypothesis that gamma V m (2/3)/ kT = G( x v) is initially based on cavity theory. It is then refined based on periodic lattice modeling, which reveals that the number N of voids per unit cell (hence the dimensionless surface tension) must depend on x v. Testing our hypothesis against data for the five ILs for which surface tension and density data are available over a wide range of temperatures collapses all of these data almost on a single curve G( x v), provided that slight (4%) self-consistent modifications are introduced on published crystallographic data for V (+) and V (-). An attempt to correlate the surface tension vs temperature data available for inorganic molten salts is similarly successful, but at the expense of larger shifts on the published ionic radii (8.8% for K; 3.3% for I). The collapsed G( x v) curves for ILs and inorganic salts do not overlap anywhere on x v space, and appear to be different from each other. The existence of a relation between gamma and x v is rationalized with a simple capillary model minimizing the energy. Our success in correlating surface tension to void fraction may apply also to other liquid properties.     

Quick analysis of baicalin in Scutellariae Radix by enzyme-linked immunosorbent assay using a monoclonal antibody

To establish an immunoassay for baicalin (BA), a hybridoma cell line (9D6) secreting a monoclonal antibody (MAb) against BA was prepared by cell fusion with splenocytes derived from a mouse immunized with BA-bovine serum albumin (BSA) conjugate and a myeloma cell line, SP2/0-Ag14. MAb 9D6 shows specific reactivity against BA and its aglycone, baicalein, but not against other natural products. We developed an enzyme-linked immunosorbent assay (ELISA) using MAb 9D6 in a competitive manner, ranging from 200 ng/mL to 2 μg/mL. After validating the developed ELISA on the basis of intra- and inter-assays and a recovery experiment, it was found that the ELISA was not only simple, but also sufficiently reliable and accurate for quality control of Scutellariae Radix. It allowed determination of BA in complex and mixed materials, such as Kampo medicines.     

Development of pyrrole-imidazole polyamide for specific regulation of human aurora kinase-A and -B gene expression

Pyrrole-imidazole polyamide (PIP) is a nuclease-resistant novel compound that inhibits gene expression through binding to the minor groove of DNA. Human aurora kinase-A (AURKA) and -B (AURKB) are important regulators in mitosis during the cell cycle. In this study, two specific PIPs (PIP-A and PIP-B) targeting AURKA and AURKB promoter regions were designed and synthesized, and their biological effects were investigated by several in vitro assays. PIP-A and PIP-B significantly inhibited the promoter activities, mRNA expression, and protein levels of AURKA and AURKB, respectively, in a concentration-dependent manner. Moreover, 1:1 combination treatment with both PIPs demonstrated prominent antiproliferative synergy (CI value [ED(50)] = 0.256) to HeLa cells as a result of inducing apoptosis-mediated severe catastrophe of cell-cycle progression. The novel synthesized PIP-A and PIP-B are potent and specific gene-silencing agents for AURKA and AURKB.     

Nanomechanical properties of reversed surfactant bilayers formed in micrometre-sized holes

Nanomechanical properties of free-standing reversed surfactant bilayers, dried foam films (DFFs), were examined via AFM by fitting local force-indentation curves with a Hertzian model. The Young's moduli of four kinds of bilayers were in a range of 10-30 MPa.     

Structures and bonding on a colloidal silver surface of the various length carboxyl terminal fragments of bombesin

Raman (RS) and surface-enhanced Raman scattering spectra (SERS) were measured for various length carboxyl terminal fragments (X-14 of amino acid sequence) of bombesin ( BN): BN13-14, BN12-14, BN11-14, BN10-14, BN9-14, and BN8-14 in silver colloidal solutions. Density functional theory (DFT) calculations of Raman wavenumbers and intensities with extended basis sets (B3LYP/6-31++G**) were performed with the aim of providing the definitive band allocations to the normal coordinates. The proposed band assignment is consistent with the assignment for similar compounds reported in the literature. The nonadsorbed and adsorbed molecular structures were deducted by detailed spectral analysis of the RS and SERS spectra, respectively. This analysis also allowed us to propose the particular surface geometry and orientation of these peptides on silver surface, and their specific interaction with the surface. For example, a SERS spectrum of BN8-14 indicates that the interaction of a thioether atom and Trp8 with the silver surface is favorable and may dictate the orientation and conformation of adsorbed peptide. One of the most prominent and common features in all of the fragments' SERS spectra is a approximately 692 cm (-1) band due to nu(C-S) accompanied by two or three bands of different C-S conformers for all, except BN8-14, which suggests that all of the above-mentioned compounds adsorb on the silver surface through the thioether atom and that the attachment of Trp8 produces limitation in a number of possible C-S conformers adopted on this surface. Our results also show clearly that His12 and CO do not interact with the colloid surface, which supports our earlier results.     

Surface-imprinted nanostructured layer-by-layer film for molecular recognition of theophylline derivatives

In this article we report the introduction of the cooperativity of various specific interactions combined with photo-cross-linking of the interlayers to yield binding sites that can realize better selectivity and imprinting efficiency of a surface molecularly imprinted LbL film (SMILbL), thus providing a new approach toward fabrication of nanostructured molecularly imprinted thin films. It involves preassembly of poly(acrylic acid) (PAA) conjugated of the theophylline residue template via a disulfide bridge, denoted as PAAtheo 15, in solution, and layer-by-layer (LbL) assembly of PAAtheo 15 and a positively charged photoreactive diazo resin (DAR) to form multilayer thin film with designed architecture. After photo-cross-linking of the film and template removal, binding sites specific to 7-(beta-hydroxyethyl)theophylline (Theo-ol) molecules are introduced within the film. Binding assay demonstrates that the SMILbL has a high selectivity of SMILbL to Theo-ol over caffeine. A control experiment demonstrates that the selectivity of SMILbL derives from nanostructured recognition sites among the layers. The imprinting amount per unit mass of the film can be 1 order of magnitude larger than that of the conventional bulk molecular imprinting systems. As this concept of construction SMILbL can be easily extended to the other molecules by the following similar protocol: its applications in building many other different molecular recognition systems are greatly anticipated.     

An enzyme-linked immunosorbent assay for aconitine-type alkaloids using an anti-aconitine monoclonal antibody

3-Succinylaconitine was conjugated with bovine serum albumin (BSA) for use as an immunogen for the preparation of a monoclonal antibody (MAb) against aconitine (Aco). Splenocytes from mice immunized with the Aco-BSA conjugate were fused with an aminopterin-sensitive mouse myeloma cell line, P3-X63-Ag8-653, and a hybridoma secreting a MAb against Aco was successfully obtained. The MAb cross-reacted with mesaconitine, hypaconitine and jesaconitine, which are Aco-type alkaloids, but not with any other compounds examined. The full measurement range of an enzyme-linked immunosorbent assay (ELISA) developed using the new MAb extended from 100 ng mL⁻¹ to 1.5 μg mL⁻¹ of Aco. The concentrations of Aco-type alkaloids in various Aconiti radixes assayed using the new ELISA method showed good agreement with previous reports.     

Self-modeling curve resolution (SMCR) analysis of near-infrared (NIR) imaging data of pharmaceutical tablets

The idea of quality by design (QbD) has been proposed in pharmaceutical field. QbD is a systematic approach to control the product performance based on the scientific understanding of the product quality and its manufacturing process. In the present study, near-infrared (NIR) imaging is utilized as a tool to achieve this concept. A practical use of a chemometrics technique called self-modeling curve resolution (SMCR) is demonstrated with NIR imaging analysis of pharmaceutical tablets containing two ingredients, a soluble active ingredient, pentoxifylline (PTX), and an insoluble excipient, palmitic acid. Concentration profiles obtained by SMCR reveal that the homogenous distribution of chemical ingredients strongly depends on the grinding time and that its process plays a central role in quantitative control, say sustained-release of PTX. In addition, pure component spectra by SMCR indicate a sequential change of specific NIR peak intensities following the increase of the grinding time. The spectra change shows a molecular structure change related to its crystallinity during grinding process. Accordingly, this study clearly demonstrates that NIR imaging combined with SMCR can be a powerful tool to reveal chemical or physical mechanism induced by the manufacturing process of pharmaceutical products and that it may be a solid solution for QbD of pharmaceutical products.     

Determination of (R)-xanthoanthrafil, a phosphodiesterase-5 inhibitor, in a dietary supplement promoted for sexual enhancement

We describe here the first case of the finding of xanthoanthrafil, a phosphodiesterase-5 inhibitor, in a dietary supplement. A methanol extract of the supplement product was first analyzed by TLC and HPLC. The results indicated that the extract contained an unknown compound. The molecular weight of the compound was 389 and the accurate mass showed its elemental composition to be C(19)H(23)N(3)O(6). Combined with this data, NMR analysis revealed the planar structure of the unknown compound to be N-(3,4-dimethoxybenzyl)-2-(1-hydroxypropan-2-ylamino)-5-nitrobenzamide. The R-configuration of this compound had been synthesized as a phosphodiesterase-5 inhibitor, formerly reported as FR226807 by Fujisawa Pharmaceutical Co., Ltd. The absolute configuration of the isolated compound was estimated to have R-configuration by its optical rotation. Considering its general properties, this compound is renamed as (R)-xanthoanthrafil with the agreement of Astellas Pharma Inc. which is the successor of Fujisawa Pharmaceutical Co., Ltd. Quantitative analysis revealed that the content of (R)-xanthoanthrafil in the product was about 31 mg/capsule.