Detection of ethanol in human body fluids by headspace solid-phase micro extraction (SPME)/capillary gas chromatography

Summary Ethanol has been found extractable from human whole blood and urine samples by headspace solid-phase micro extraction (SPME) with a Carbowax/divinylbenzene-coated fiber. After heating a vial containing the body fluid sample with ethanol, and isobutanol as internal standard (IS) at 70°C in the presence of (NH₄)₂SO₄, a Carbowax/divinylbenzene-coated SPME fiber was exposed in the headspace of the vial to allow adsorption of the compounds. The fiber needle was then injected into a middle-bore capillary gas chromatography (GC) port. The headspace SPME-GC gave intense peaks for both compounds; a small amount of background noises appeared, but did not interfere with the detection of the compounds. Recoveries of ethanol and IS were 0.049 and 0.026% for whole blood, respectively, and 0.054 and 0.085% for urine, respectively. The calibration curves for ethanol showed excellent linearity in the range of 80–5000 mg L^–1 for whole blood and 40–5000 mg L^–1 for urine; the detection limits for both samples were 20 and 10 mg L^–1, respectively. The data on actual determination of ethanol after the drinking of beer are also presented for two subjects.     

Molecular structures,electronic spectra,and aromaticity of 1,6- and 1,8-dioxa analogues of pyrene and benzo[a]pyrene. Semiempirical molecular orbital calculations

The molecular structures of [1]benzopyrano[6,5,4-def][1]benzopyran, [2]benzopyrano[7,8,1,def]-1-benzopyran, 1-benzopyrano[6,5,4-mna]xanthene, and 2-benzopyrano[7,8,1-mna]xanthene have been optimized by using the PM3 semiemperical MO method. These calculated molecules have been shown to be planar. Their aromaticity has been investigated by use of the HOMA index. The molecules are found to be less aromatic than the correspolding parednt hydrocarbons, pyrene and benzo[a]pyrene. The CNDO/S MO method has been used to interpret th experimental uv-vis specrtoscopic data. The result of the PM3, CNDO/S and HOMA-index clculations are in good arteement with the experimental data.     

The Macromolecular Route to Chiral Amplification

Cooperative phenomena, described by one-dimensional statistical physical methods, are observed between the enantiomeric characteristics of monomeric materials and the polymers they produce. The effect of minute energies associated with this amplified chirality, although currently not interpretable, can be easily measured. Nonlinear relationships between enantiomeric excess or enantiomeric content and polymer properties may offer the possibility of developing chiral catalysts and chiral chromatographic materials in which the burden of large enantiomeric excess or content may be considerably alleviated. New approaches to information and sensor technology may become possible.     

Coordination and Redox Isomerization in the Reduction of a Uranium(III) Monoarene Complex

Synthetic studies on the redox chemistry of trivalent uranium monoarene complexes were undertaken with a complex derived from the chelating tris(aryloxide)arene ligand (^Ad,MeArO)₃mes^3?. Cyclic voltammetry of [{(^Ad,MeArO)₃mes}U^III] ( 1 ) revealed a nearly reversible and chemically accessible reduction at ?2.495 V vs. Fc/Fc⁺—the first electrochemical evidence for a formally divalent uranium complex. Chemical reduction of 1 indicates that reduction induces coordination and redox isomerization to form a uranium(IV) hydride, and addition of a crown ether results in hydride insertion into the coordinated arene to afford uranium(IV) complexes. This stoichiometric reaction sequence provides structural insight into the mechanism of arene functionalization at diuranium inverted sandwich complexes.     

Rational Design and Identification of a Non‐Peptidic Aggregation Inhibitor of Amyloid‐β Based on a Pharmacophore Motif Obtained from cyclo[‐Lys‐Leu‐Val‐Phe‐Phe‐]

Inhibition of pathogenic protein aggregation may be an important and straightforward therapeutic strategy for curing amyloid diseases. Small‐molecule aggregation inhibitors of Alzheimer’s amyloid‐β (Aβ) are extremely scarce, however, and are mainly restricted to dye‐ and polyphenol‐type compounds that lack drug‐likeness. Based on the structure‐activity relationship of cyclic Aβ16–20 (cyclo‐[KLVFF]), we identified unique pharmacophore motifs comprising side‐chains of Leu², Val³, Phe⁴, and Phe⁵ residues without involvement of the backbone amide bonds to inhibit Aβ aggregation. This finding allowed us to design non‐peptidic, small‐molecule aggregation inhibitors that possess potent activity. These molecules are the first successful non‐peptidic, small‐molecule aggregation inhibitors of amyloids based on rational molecular design.     

Self‐Replication and Amplification of Enantiomeric Excess of Chiral Multifunctionalized Large Molecules by Asymmetric Autocatalysis

Self‐replication of large chiral molecular architectures is one of the great challenges and interests in synthetic, systems, and prebiotic chemistry. Described herein is a new chemical system in which large chiral multifunctionalized molecules possess asymmetric autocatalytic self‐replicating and self‐improving abilities, that is, improvement of their enantioenrichment in addition to the diastereomeric ratio. The large chiral multifunctionalized molecules catalyze the production of themselves with the same structure, including the chirality of newly formed asymmetric carbon atoms, in the reaction of the corresponding achiral aldehydes and reagent. The chirality of the large multifunctionalized molecules controlled the enantioselectivity of the reaction in a highly selective manner to construct multiple asymmetric stereogenic centers in a single reaction.     

The Effects of Ultraviolet Eye Irradiation on Dextran Sodium Sulfate‐Induced Ulcerative Colitis in Mice

Ultraviolet (UV) eye irradiation denatures the cells of the intestine. This study examined the action of UVA and UVB on dextran sodium sulfate (DSS)‐induced ulcerative colitis. We produced a mouse model of ulcerative colitis by administering DSS for 5 days and irradiated the eye with UVB or UVA for each day of the DSS treatment period. DSS‐induced ulcerative colitis was deteriorated by the UVB eye irradiation. Conversely, the symptoms improved with UVA eye irradiation. The levels of adrenocorticotropic hormone (ACTH), corticotropin‐releasing hormone (CRH), urocortin 2, interleukin (IL)‐18, IL‐6 and histamine in the blood increased after the UVB eye irradiation of DSS‐treated mice (UVB/DSS‐treated mice). In contrast, the β‐endorphin level in the blood of the UVA/DSS‐treated mice increased and the levels of urocortin 2, tumor necrosis factor (TNF)‐α and histamine decreased. Furthermore, in the colon, the expression of melanocortin‐2 receptors (MC2R) increased in the UVB/DSS‐treated mice, while the expression of μ‐opioid receptors increased in the UVA/DSS‐treated mice. When an ACTH inhibitor was administered, UVB eye irradiation caused the deterioration of DSS‐treated ulcerative colitis, while the effect of UV eye irradiation disappeared with a μ‐opioid receptor antagonist. These results suggested that UV eye irradiation plays an important role in DSS‐induced ulcerative colitis.     

Direct Observation of Ordered High‐Spin–Low‐Spin Intermediate States of an Iron(III) Three‐Step Spin‐Crossover Complex

A neutral mononuclear Fe^III complex [Fe^III(H‐5‐Br‐thsa‐Me)(5‐Br‐thsa‐Me)]?H₂O ( 1 ; H₂‐5‐Br‐thsa‐Me=5‐bromosalicylaldehyde methylthiosemicarbazone) was prepared that exhibited a three‐step spin‐crossover (SCO) with symmetry breaking and a 14 K hysteresis loop owing to strong cooperativity. Two ordered intermediate states of 1 were observed, 4HS–2LS and 2HS–4LS, which exhibited reentrant phase‐transition behavior. This study provides a new platform for examining multistability in SCO complexes.     

Theoretical Modelling and Facile Synthesis of a Highly Active Boron‐Doped Palladium Catalyst for the Oxygen Reduction Reaction

A highly active alternative to Pt electrocatalysts for the oxygen reduction reaction (ORR), which is the cathode‐electrode reaction of fuel cells, is sought for higher fuel‐cell performance. Our theoretical modelling reveals that B‐doped Pd (Pd‐B) weakens the absorption of ORR intermediates with nearly optimal binding energy by lowering the barrier associated with O₂ dissociation, suggesting Pd‐B should be highly active for ORR. In fact, Pd‐B, facile synthesized by an electroless deposition process, exhibits 2.2 times and 8.8 times higher specific activity and 14 times and 35 times less costly than commercial pure Pd and Pt catalysts, respectively. Another computational result is that the surface core level of Pd is negatively shifted by B doping, as confirmed by XPS, and implies that filling the density of states related to the anti‐bonding of oxygen to Pd surfaces with excess electrons from B doping, weakens the O bonding to Pd and boosts the catalytic activity.     

Absolute stereochemistry of amphidinolides G and H

[structure: see text] Absolute stereochemistry of amphidinolides G (1) and H (2), potent cytotoxic 27- and 26-membered macrolides, respectively, isolated from a marine dinoflagellate Amphidinium sp., was determined by X-ray diffraction analysis, synthesis of a degradation product (3) of 2, and interconversion between 1 and 2.