Titanium-Mediated Cyclization of ω-Vinyl Imides in Alkaloid Synthesis: Isoretronecanol, Trachelanthamidine, 5-Epitashiromine, and Tashiromine

A new method for the stereocontrolled synthesis of pyrrolizidine and indolizidine alkaloids by means of titanium-mediated cyclization of ω-vinyl imides is described. The general procedure involves treatment of readily available ω-vinyl imides 9 and 10 with 2.5 equiv of cyclopentylmagnesium chloride in the presence of ClTi(O-i-Pr)3 (1.1 equiv) and subsequent stereoselective reduction of the N-acylaminal group. The cis and trans ring junction stereoisomers can be stereoselectively prepared by catalytic hydrogenation (H2, PtO2, EtOAc) and NaCNBH3 reduction (TFA, MeOH), respectively. Finally, treatment of the resulting lactams with LAH or diborane afforded the target alkaloids 1−8 in good yields

Revealing Compositional Evolution of PdAu Electrocatalyst by Atom Probe Tomography

Pd-based electro-catalysts are a key component to improve the methanol oxidation reaction (MOR) kinetics from alcohol fuel cells. However, the performance of such catalysts is degraded over time. To understand the microstructural/atomic scale chemical changes responsible for such an effect, scanning (transmission) electron microscopy measurements and atom probe tomography were performed after accelerated degradation tests. No morphological changes are observed after 1000 MOR cycles. In contrast, (1) Pd and B are leached from PdAu nanoparticles and (2) Au-rich regions are formed at the surface of the catalyst. These insights highlight the importance of understanding the chemical modification occurring upon MOR to design new catalysts

Exploring the Surface Segregation of Rh Dopants in PtNi Nanoparticles through Atom Probe Tomography Analysis

Proton-exchange membrane fuel cells hold promise as energy conversion devices for hydrogen-based power generation and storage. However, the slow kinetics of oxygen reduction at the cathode imposes the need for highly active catalysts, typically Pt or Pt based, with a large available area. The scarcity of Pt increases the deployment and operational cost, driving the development of novel highly active material systems. As an alternative, a Rh-doped PtNi nanoparticle has been suggested as a promising oxygen reduction catalyst, but the three-dimensional distributions of constituent elements in the nanoparticles have remained unclear, making it difficult to guide property optimization. Here, a combination of advanced microscopy and microanalysis techniques is used to study the Rh distribution in the PtNi nanoparticles, and Rh surface segregation is revealed, even with an overall Rh content below 2 at. %. Our findings suggest that doping and surface chemistry must be carefully investigated to establish a clear link with catalytic activity that can truly be established

Supplementary Methods, Supplementary Figures 1 to 9, and Supplementary Tables 1 to 3 from Enhancement of the Tumor Penetration of Monoclonal Antibody by Fusion of a Neuropilin-Targeting Peptide Improves the Antitumor Efficacy

PDF - 2613K, Figure S1: Structural analysis of NRP1, NRP2, and Sema3A, and their interactions to facilitate the understanding of the interactions between Sema3A and NRP1/2. Figure S2: SDS-PAGE analyses of the purified proteins showing that NRP1/2-b1b2 domains, Fc-A22, and Fc-A22p are well prepared. Figure S3: FACS and confocal fluorescence data showing that Fc-A22p, but not Fc, specifically interacts with cell-surface expressed NRP1/2 undergoing cellular internalization. Figure S4: Cell viability data showing that Fc-A22p does not cause significant cytotoxicity on HUVECs and tumor cells. Figure S5: Tumor tissue analyzing data showing that Fc-A22p homes to tumor, induces vascular permeability, and downregulates VE-cadherin in endothelial cells and E-cadherin in tumor cells. Figure S6: Confocal fluorescence data showing that Fc-A22p causes downregulation of VE-/E-cadherin and their dissociation from F-actin cytoskeleton resulting in disruption of cell-cell contacts. Figure S7: Data showing the expression and biochemical characterization of mAb-A22p antibodies, cetuximab-A22p and trastuzumab-A22p, compared with the parent mAbs. Figure S8: Cell proliferation and Western blotting data showing that cetuximab-A22p exerts in vitro biological activities comparable to those of cetuximab in A431 and FaDu tumor cells. Figure S9: Human tumor xenografted mouse data showing that mAb-A22p antibodies show increased tumor homing and penetration and thus superior in vivo anti-tumor efficacy, compared with the parent mAbs. Table S1: SPR data showing the kinetic binding parameters for the interactions of Fc-A22, Fc-A22p, VEGF165, and Sema3A with soluble NRP1-b1b2 and NRP2-b1b2 fragments. Table S2: Purification yields of Fc proteins and antibodies obtained from transient expression in HEK293F cells. Table S3: SPR data showing the kinetic binding parameters for the interactions of mAbs and mAb-A22p antibodies with the indicated proteins. Supplementary Materials and Methods: Detailed description of Reagents; Recombinant protein expression and purification; Construction, expression, and purification of antibodies; Binding analysis by ELISA; Surface plasmon resonance (SPR); Flow cytometric analysis; Cell proliferation assay; Western blotting and immunoprecipitation; Co-localization studies by confocal immunofluorescence microscopy; RNA Interference; Ex vivo tumor penetration assays.</p

Sequence alignments and antigenic sites.

<p>(A) Sequence alignments of variable region of GC0587 and GC0757 (upper panel) and H1 HAs (lower panel). Residues in CDRs are in blue open boxes and residues that interact with HA are highlighted in blue filled boxes. Epitopes in H1 HAs are highlighted in pink, and more conserved residues are highlighted in red. Potential glycosylation sites are highlighted in green. (B) Surface representations of KR01 HAs (gray) and Fab fragments (dark blue and light blue for H-chain and L-chain, respectively). Antigenic sites are colored in red for highly conserved residues and pink for moderately conserved residues. Amino acid residues involved in the interactions between KR01 HA and Fab0587 are colored in blue and slate. Insets are surface charge representations with contours from −10 (red) to+10 (blue) kT through 0 (white). (C) Detailed interactions of HA with Fab0587. HA and Fab are colored in orange and blue, respectively. Residues that contribute to the interactions are represented as stick models. LCDR1 and LCDR3 are colored in purple and green, respectively (upper panel), and HCDR2 and HCDR3 are colored in magenta and cyan, respectively (lower panel). (D) Residues found at other structurally characterized antibody complexes are colored in yellow, those at both Fab0587 and other antibody complexes are in orange, and those against GC0587 are in red. Classical antigenic sites are colored in light pink (Ca, Cb, Sa, and Sb) and those at both Fab0587 antigenic sites are in pink.</p

Comparison of Fab binding sites.

<p>Residues involved in interactions between HA and Fab0587 are represented as a ball-and-stick model and hydrophilic interactions as dotted line. Residues of HA in complex with Fab0587 are colored in orange and H-chains of Fab0587 and Fab0757 are in dark and light blue, respectively. (A) Comparison of LCDR3, (B) HCDR3. (C) Superposition of KR01 HA bound to Fab0587 (magenta), KR01 HA bound to Fab0757 (dark gray), free KR01 HA (yellow), 1918 pdm HA (green), Fab0587 (purple), and Fab0757 (light teal). Surface representations are based on the KR01HA-Fab0587 complex structure.</p

Data and refinement statistics.

<p>*R_merge = Σ|I - <i>|/Σ<i>, where I and <i> are the measured and averaged intensities of multiple measurements of the same reflection, respectively. The summation is over all the observed reflections.</i></i></i></p><p><i><i><i>**R = Σ|<i>F</i>_o – <i>F</i>_c|/Σ|<i>F</i>_o| calculated for all observed data. R_free = Σ|<i>F</i>_o – <i>F</i>_c|/Σ|<i>F</i>_o| calculated for a specified number of randomly chosen reflections that were excluded from the refinement.</i></i></i></p><p><i><i>***Calculated using PROCHECK <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089803#pone.0089803-Laskowski2" target="_blank">[41]</a>.</i></i></p

In vitro neutralization activity of antibodies against a panel of HA from influenza A viruses.

<p>+represents a positive neutralization activity of each antibody determined by ELISA and –represents a negative neutralizing activity.</p><p>*A/California/04/2009(H1N1), A/Brisbane/59/2007(H1N1), A/California/04/2009(H1N1), A/Brevig Mission/1/1918(H1N1), A/California/07/2009(H1N1), A/Japan/305/1957(H2N2), A/Brisbane/10/2007(H3N2), A/Anhui/1/2005(H5N1), A/bar-headed goose/Qinghai/14/2008(H5N1), A/Indonesia/5/2005(H5N1), A/turkey/Turkey/1/2005(H5N1), A/Viet Nam/1194/2004(H5N1), A/Viet Nam/1203/2004(H5N1), A/Netherlands/219/03(H7N7).</p

Binding affinities of monoclonal antibodies against H1 HAs.

<p>ELISA analysis results of monoclonal antibodies against KR01 and CU44 HAs that were coated on the 96-well plates to which 0 to 10 µg/ml of antibodies were added. Absorbance was measured after addition of TMB solution to each well at 490 nm.</p

Overview of the structures of KR01 HA and its complex with Fab0587.

<p>(A) Structure of KR01 HA-Fab0587 complex. HA are colored in orange and light brown, H-chains are blue and green, and L-chains are light blue and lime. (B) Superposition of KR01 HA in Fab0587 complex and head domain of KR01 HA structures, and (C) superposition of stem region between Fab0587 bound KR01 HA and Free KR01 HA. Gray color represents free HA, and orange color represents HA in complex.</p