Characterization of sodium alginate and its block fractions by surface‐enhanced Raman spectroscopy

The surface‐enhanced Raman scattering (SERS) of sodium alginates and their hetero‐ and homopolymeric fractions obtained from four seaweeds of the Chilean coast was studied. Alginic acid is a copolymer of β‐D ‐mannuronic acid (M) and α‐L guluronic acid (G), linked 1 → 4, forming two homopolymeric fractions (MM and GG) and a heteropolymeric fraction (MG). The SERS spectra were registered on silver colloid with the 632.8 nm line of a He Ne laser. The SERS spectra of sodium alginate and the polyguluronate fraction present various carboxylate bands which are probably due to the coexistence of different molecular conformations. SERS allows to differentiate the hetero‐ and homopolymeric fractions of alginic acid by characteristic bands. In the fingerprint region, all the poly‐D ‐mannuronate samples present a band around 946 cm⁻¹ assigned to C O stretching, and C C H and C O H deformation vibrations, a band at 863 cm⁻¹ assigned to deformation vibration of β‐C₁ H group, and one at 799–788 cm⁻¹ due to the contributions of various vibration modes. Poly‐L ‐guluronate spectra show three characteristic bands, at 928–913 cm⁻¹ assigned to symmetric stretching vibration of C O C group, at 890–889 cm⁻¹ due to C C H, skeletal C C, and C O vibrations, and at 797 cm⁻¹ assigned to α C₁ H deformation vibration. The heteropolymeric fractions present two characteristic bands in the region with the more important one being an intense band at 730 cm⁻¹ due to ring breathing vibration mode. Copyright © 2009 John Wiley & Sons, Ltd.     

Kalirin12 interacts with dynamin

Background  

Guanine nucleotide exchange factors (GEFs) and their target Rho GTPases regulate cytoskeletal changes and membrane trafficking. Dynamin, a large force-generating GTPase, plays an essential role in membrane tubulation and fission in cells. Kalirin12, a neuronal RhoGEF, is found in growth cones early in development and in dendritic spines later in development.     

Rapid Isocratic HPLC Method and Sample Extraction Procedures for Measuring Carotenoid,Retinoid, and Tocopherol Concentrations in Human Blood and Breast Milk for Intervention Studies

Vitamin A deficiency continues to be a major public health concern in the developing world effecting over 200 million people. Interventions including carotenoid-rich fruits and vegetables, containing α- and β-carotene, and β-cryptoxanthin, are being tested for their potential to alleviate vitamin A deficiency in several countries. Thus, there is a need for a faster isocratic reverse-phase high pressure liquid chromatography (HPLC) method than the methods currently available. Efficient extraction procedures for biological samples are also valuable to save time, materials, and cost. We developed an HPLC method and compared several extraction methods for carotenoids, retinoids, and vitamin E in plasma and human breast milk. The method uses an Agilent 1100 system equipped with a Waters Spherisorb ODS2 column (3 × 125 mm 3 μm) and similar guard column (ThermoScientific ODS2 3 × 20 mm 3 μm). Mobile phase of 7:2:1 acetonitrile:dichloromethane:methanol was run at 0.5 mL min⁻¹, and run times were complete in approximately 8 min. This rapid method uses little solvent and provides excellent results in the analysis of these fat-soluble nutrients. Analyte measurements were repeatable using standards and plasma and were accurate compared to NIST certified and reference serum values. The validated HPLC method was applied to the analysis of plasma samples from a vitamin A intervention study.

     

Selective Inhibition of Lysine‐Specific Demethylase 5A (KDM5A) Using a Rhodium(III) Complex for Triple‐Negative Breast Cancer Therapy

Lysine‐specific demethylase 5A (KDM5A) has recently become a promising target for epigenetic therapy. In this study, we designed and synthesized metal complexes bearing ligands with reported demethylase and p27 modulating activities. The Rh(III) complex 1 was identified as a direct, selective and potent inhibitor of KDM5A that directly abrogate KDM5A demethylase activity via antagonizing the KDM5A‐tri‐/di‐methylated histone 3 protein–protein interaction (PPI) in vitro and in cellulo. Complex 1 induced accumulation of H3K4me3 and H3K4me2 levels in cells, causing growth arrest at G1 phase in the triple‐negative breast cancer (TNBC) cell lines, MDA‐MB‐231 and 4T1. Finally, 1 exhibited potent anti‐tumor activity against TNBC xenografts in an in vivo mouse model, presumably via targeting of KDM5A and hence upregulating p27. Moreover, complex 1 was less toxic compared with two clinical drugs, cisplatin and doxorubicin. To our knowledge, complex 1 is the first metal‐based KDM5A inhibitor reported in the literature. We anticipate that complex 1 may be used as a novel scaffold for the further development of more potent epigenetic agents against cancers, including TNBC.     

Theoretical study of the structure of tetraborane(10)

Fully optimized geometries are reported for two possible isomers of B₄H₁₀. At the restricted Hartree-Fock level, the unobserved bisdiborane isomer is lower in energy than the observed isomer. Generalized-molecular-orbital, configuration-interaction calculations show that electron correlation is responsible for this reversal. Electron correlation may be important in stabilizing other cluster molecules.     

Strained heterocyclic systems. 11. Crystal and molecular structure of 1,2-dihydrocyclobuta[b]quinoline

The structure of the title compound (1) has been elucidated by an X-ray crystal determination. The crystals are triclinic, space group PI with a unit cell of dimensions a = 6.6109(5), b = 7.5939(4), c = 9.3171(6), α = 77.133(5), β = 75.566(6), γ = 63.575(5). The model was refined to an R value (unweighted) of 4.3% for 1551 independent reflections. The distortion of the heterocyclic ring, with a CNC bond angle of 112.5,° is in accordance with a prior calculation and relates to the observed reduction in basicity.     

Products of threads

A topological semigroup S is a thread if S is a metric arc in which one endpoint is the identity of S and the other endpoint is the zero of S. Let [x0, x₁] and [y₀, y₁] be subsets of threads in a semigroup S. Then define A(x₀, x₁) = x [x₀, x₁] | xy₁ = x₁y for some y [y₀, y[in1}]). The main result of this paper states that if X and Y are threads in a topological semigroup S, then XY is an arc or a point, or contains a two-cell.This paper is part of the author's doctoral dissertation written under the direction of Professor D. R. Brown at the University of Houston. This work was supported in part by an NSF Science Faculty Fellowship.     

Reaction of the thiolsulfonate group with the aromatic nucleus: A new ring closure

The double ring closure of N,N-bis[2- (alkyl- or arylsulfonylthio)ethyl]anilines to form 2,3,5,6-tetrahydro[1,4]thiazino[4,3,2-de][1,4]benzothiazines, a new ring system, is reported. The effects of various benzene ring substituents upon the ring closure are described.