Experiments on the Total Synthesis of Lysolipin I. Part I. On Configuration and Conformation of 5-Substituted 1,2,3,4,4a,9,10,10a-Ocathydrophenanthrene-4,9-diones

The substituted 1,2,3,4,4a,9,10,10a-octahydrophenanthrene-4,9-dione 2 , synthesized from the cyclohexanone 8 and quinone 11 (Scheme 2), was found by X-ray analysis adn ¹H-NMR studies to be the isomer with cis-junction of the saturated rings. The cis-fusion could also be determined from the ¹H-NMR data of the related compound 17 (Scheme 4), which was previously considered to be trans-fused. In contrary to previous argumentations, the interaction of the C(4)-carbonyl O-atom of trans-fused octahydrophenanthenes is more severe with a 5-methoxy than with a 5-methyl substituent.     

Solvability of the\bar \partial problem withC ∞ regularity up to the boundary on wedges of ℂNproblem withC ∞ regularity up to the boundary on wedges of ℂN

For awedge W of ?^N, we introduce an intrinsic condition of weakq-pseudoconvexity which can be expressed in terms ofq-subharmonicity both of a defining function or an exhaustion function. Under this condition we prove solvability of the $\bar \partial $ system for forms withC ^∞ (W)-coefficients of degree ≥q+1. Our method relies on theL ²-estimates by Hörmander. ForC ^∞(W) solvability we refer to Hörmander (if ?W∈C ²), and to Zampieri (for general wedgesW). ForC ^∞ (W) solvability and with ?W∈C ², we 025 refer to Dufresnoy (ifq=0), Michel (if the number of negative Levieigenvalues of ?W is constant), and finally Zampieri (for more generalq-pseudoconvexity).     

Unexpected Acetylation of Endogenous Aliphatic Amines by Arylamine N‐Acetyltransferase NAT2

N‐Acetyltransferases play critical roles in the deactivation and clearance of xenobiotics, including clinical drugs. NAT2 has been classified as an arylamine N‐acetyltransferase that mainly converts aromatic amines, hydroxylamines, and hydrazines. Herein, we demonstrate that the human arylamine N‐acetyltransferase NAT2 also acetylates aliphatic endogenous amines. Metabolomic analysis and chemical synthesis revealed increased intracellular concentrations of mono‐ and diacetylated spermidine in human cell lines expressing the rapid compared to the slow acetylator NAT2 phenotype. The regioselective N⁸‐acetylation of monoacetylated spermidine by NAT2 answers the long‐standing question of the source of diacetylspermidine. We also identified selective acetylation of structurally diverse alkylamine‐containing drugs by NAT2, which may contribute to variations in patient responses. The results demonstrate a previously unknown functionality and potential regulatory role for NAT2, and we suggest that this enzyme should be considered for re‐classification.     

Chemical Synthesis of Native S-Palmitoylated Membrane Proteins through Removable-Backbone-Modification-Assisted Ser/Thr Ligation

The preparation of native S-palmitoylated (S-palm) membrane proteins is one of the unsolved challenges in chemical protein synthesis. Herein, we report the first chemical synthesis of S-palm membrane proteins by removable-backbone-modification-assisted Ser/Thr ligation (RBM^GABA-assisted STL). This method involves two critical steps: 1) synthesis of S-palm peptides by a new γ-aminobutyric acid based RBM (RBM^GABA) strategy, and 2) ligation of the S-palm RBM-modified peptides to give the desired S-palm product by the STL method. The utility of the RBM^GABA-assisted STL method was demonstrated by the synthesis of rabbit S-palm sarcolipin (SLN) and S-palm matrix-2 (M2) ion channel. The synthesis of S-palm membrane proteins highlights the importance of developing non-NCL methods for chemical protein synthesis.     

Structural Elucidation of Selective Solvatochromism in a Responsive-at-Metal Cyclometalated Platinum(II) Complex

We report the synthesis, characterization, and spectroscopic investigations of a new responsive-at-metal cyclometalated platinum(II) complex. With mild chemical oxidants and reductants, it was possible to obtain the same complex in three different oxidation states and each of these complexes was structurally characterized by single-crystal X-ray diffraction. We discovered that the platinum(II) complex displays strong solvatochromism in the solid state, which can be attributed to modulation of Pt⋅⋅⋅Pt interactions that results in switching between optical and photoluminescent states. Incorporating responsive-at-metal species as dynamic components in nanostructured materials might facilitate response amplification, sensing, actuation, or self-healing processes.     

Raman fingerprint of chromate,aluminate and ferrite spinels

Synthetic and natural spinel single crystals having compositions closely approaching spinel end‐members ZnCr₂O₄, MgCr₂O₄, FeCr₂O₄, ZnAl₂O₄, MgAl₂O₄, CoAl₂O₄, FeAl₂O₄, MnAl₂O₄, MgFe₂O₄, and FeFe₂O₄ were investigated by Raman spectroscopy in the 100–900 cm⁻¹ range using both the red 632.8 nm line of a He‐Ne laser and the blue 473.1 nm line of a solid‐state Nd : YAG laser. Each end‐member exhibits a Raman fingerprint with at least one peculiar peak in terms of Raman shift and relative intensity. Chromates and ferrites exhibit the most intense A_1g mode at around 680 cm⁻¹, at lower wavenumbers than in the aluminates, in agreement with the heavier atomic mass of Cr and Fe with respect to Al. For aluminate spinels, the most intense and diagnostic peaks in the spectrum are as follows: F_2g(1) at 202 cm⁻¹ for MnAl₂O₄, E_g at 408 cm⁻¹ for MgAl₂O₄, F_2g(2) at 516 cm⁻¹ for CoAl₂O₄, F_2g(3) at 661 cm⁻¹ for ZnAl₂O₄, and A_1g at 748 cm⁻¹ for FeAl₂O₄. Noteworthy, analyzing the A_1g, F_2g(3), and, in particular, the E_g peak positions, it is possible to establish which subgroup a spinel belongs to; moreover, a careful inspection of both position and relative intensity of the same peaks allows the determination of the end‐member type. Copyright © 2015 John Wiley & Sons, Ltd.     

Solvent systems for countercurrent chromatography: an aqueous two phase liquid system based on a room temperature ionic liquid

A new aqueous two phase liquid system (ATPS) based on the ionic liquid 1-butyl-3-methyl imidazolium chloride (BMIM Cl), potassium dibasic phosphate (K(2)HPO(4)) and water was recently proposed in the literature. The full phase diagram of this ATPS was prepared and some tie lines were fully determined. It was compared to classical ATPSs based on polyethylene glycol with an average molecular mass of 1000 (PEG 1000) and 10,000 (PEG 10000) and K(2)HPO(4). Two countercurrent chromatography (CCC) columns, a hydrostatic Sanki and a J type hydrodynamic CCC columns were used to test the liquid phase retention of these ATPSs in all possible configurations. It was found that the BMIM Cl ATPS liquid phases were much easier to retain in the two CCC columns than the PEG 1000 ATPS phases. Using protein and alcohol solutes, it was established that the BMIM Cl ATPS has a polarity completely different from that of the PEG 1000 ATPS. For example, ovalbumin partitions equally between the two phases of the PEG 1000 ATPS (K(D)=1.4) when it is completely located in the BMIM Cl upper phase of the ionic liquid ATPS (K(D)=180). The discrimination factor of the ionic liquid system and its intrinsic hydrophobicity were respectively found three times higher and ten times lower than the respective values of the PEG 1000 ATPS.     

Number 83

Reviews are listed in order of appearance in the sources indicated. In multidisciplinary review journals, only those reviews which fall within the scope of this Journal are included. Sources are listed alphabetically in three categories: regularly issued review journals and series volumes, contributed volumes, and other monographs. Titles are numbered serially, and these numbers are used for reference in the index. Major English-language sources of critical reviews are covered. Encyclopedic treatises, annual surveys such as Specialist Periodical Reports, and compilations of symposia proceedings are omitted. This installment of Recent Reviews covers principally the middle part of the 2006 literature. Previous installment: J. Org. Chem. 2006, 71(20), 7923-30.     

Profiling of non-esterified fatty acids in human plasma using liquid chromatography-electron ionization mass spectrometry

This paper focuses on the development of a novel approach to analyze underivatized fatty acids in human plasma. The method is based on liquid–liquid extraction followed by reversed phase liquid chromatography coupled to direct-electron ionization mass spectrometry (LC-Direct-EI-MS). The assay is validated. Calibrations show satisfactory linearity and precision in the investigated range of linearity. Recoveries span from 75% to 104%. The method limits of detection, varying from 0.53 to 5.35 μM, are satisfactory for the quantitation of non-esterified fatty acids (NEFAs) in plasma at physiological levels. The method has been successfully applied to the NEFAs profiling of plasma samples from healthy adult volunteers and subjects affected by diabetes mellitus. Compared with published protocols based on gas chromatography–mass spectrometry and liquid chromatography coupled to electrospray ionization mass spectrometry, this method does not require derivatization and does not show matrix effects, thus simplifying sample preparation procedure and reducing the total time of analysis to approximately 90 min. In addition, Direct-EI-MS allows the acquisition of high-quality NIST library-matchable EI spectra, allowing an easy-to-obtain identification of the target NEFAs.     

On semilinear elliptic equations with borderline Hardy potentials

In this paper, we study the asymptotic behavior of solutions of an elliptic equation near the singularity of an inverse square potential with a coefficient related to the best constant for the Hardy inequality. Due to the presence of a borderline Hardy potential, a proper variational setting has to be introduced in order to provide a weak formulation of the equation. An Almgren-type monotonicity formula is used to determine the exact asymptotic behavior of solutions.