Revised Stereochemistry of Ceramide-Trafficking Inhibitor HPA-12 by X‑ray Crystallography Analysis

In response to Berkeš’s report revising the stereochemistry of HPA-12, an important ceramide-trafficking inhibitor that was discovered and synthesized and its stereochemistry determined in 2001, the synthesis and the stereochemistry were reinvestigated. A large-scale synthetic method for HPA-12 based on a Zn-catalyzed asymmetric Mannich-type reaction in water was developed. Single crystals of HPA-12 for X-ray crystallographic analysis were obtained from ethyl propionate/<i>n</i>-hexane, and the stereochemistry was definitely determined to be 1<i>R</i>,3<i>S</i>, consistent with Berkeš’s revised structure

Halichonadins K and L, New Dimeric Sesquiterpenoids from a Sponge <i>Halichondria</i> sp.

Two new structurally unique dimeric sesquiterpenoids, halichonadins K (<b>1</b>) and L (<b>2</b>), were isolated from an Okinawan marine sponge <i>Halichondria</i> sp. The structures of <b>1</b> and <b>2</b> were elucidated on the basis of spectroscopic analysis including a single crystal X-ray diffraction analysis and chemical conversion. Halichonadins K (<b>1</b>) and L (<b>2</b>) are homodimers of the eudesmane sesquiterpene linked with a piperidine ring through amide bonds. Halichonadin K (<b>1</b>) showed moderate cytotoxicity against KB cells

Halichonadins K and L, New Dimeric Sesquiterpenoids from a Sponge <i>Halichondria</i> sp.

Two new structurally unique dimeric sesquiterpenoids, halichonadins K (<b>1</b>) and L (<b>2</b>), were isolated from an Okinawan marine sponge <i>Halichondria</i> sp. The structures of <b>1</b> and <b>2</b> were elucidated on the basis of spectroscopic analysis including a single crystal X-ray diffraction analysis and chemical conversion. Halichonadins K (<b>1</b>) and L (<b>2</b>) are homodimers of the eudesmane sesquiterpene linked with a piperidine ring through amide bonds. Halichonadin K (<b>1</b>) showed moderate cytotoxicity against KB cells

Spectroscopic Tracking of Schiff Base Compounds’ Hydrogen Bonding Reorganization Associated with Solid-to-Solid Phase Transition

A series of 2,6-dihydroxynaphthalene-1-methylidene alkylamines whose alkyl chain lengths ranged from 9 to 12 was spectroscopically examined. Transmission ultraviolet–visible absorption microspectroscopy revealed that the spectra of solid thin-films of the crystalline samples showed two distinct profiles depending on polymorphs as well as on alkyl chain length. We concluded that these spectral changes occurred not because of conventional intramolecular proton transfer but because of the molecules’ interactions with an external proton source, that is, the intermolecular proton transfer. The spectral changes were accompanied by changes in the intermolecular hydrogen bonding network. When a crystal of a sample compound was heated, its spectrum changed dramatically before the crystal underwent a solid-to-solid phase transition to another polymorph. We concluded that these spectral changes indicated strengthening of intermolecular hydrogen bonding or intermolecular proton transfer, which would have triggered a drastic change in the hydrogen bonding network structure

Pleurocins A and B: Unusual 11(9 → 7)-<i>abeo</i>-Ergostanes and Eringiacetal B: A 13,14-<i>seco</i>-13,14-Epoxyergostane from Fruiting Bodies of <i>Pleurotus eryngii</i> and Their Inhibitory Effects on Nitric Oxide Production

Two novel 11(9 → 7)-<i>abeo</i>-ergostane-type steroids, named pleurocins A (<b>1</b>) and B (<b>2</b>), a 13,14-<i>seco</i>-13,14-epoxy ergostane, named eringiacetal B (<b>3</b>), and an ergostane steroid (<b>4</b>) were isolated from the fruiting bodies of <i>Pleurotus eryngii</i> (Pleurotaceae). Their structures were determined by spectroscopic data and X-ray crystallography. A possible biogenesis pathway for <b>1</b>–<b>3</b> was also described. Compounds <b>1</b>–<b>3</b> exhibited inhibitory activities against NO production with almost no cytotoxicity at concentrations lower than 30 μM

Investigation of the Noncovalent Binding Mode of Covalent Proteasome Inhibitors around the Transition State by Combined Use of Cyclopropylic Strain-Based Conformational Restriction and Computational Modeling

To develop potent covalent inhibitors, the noncovalent interactions around the transition state to form covalent bonding should be optimized because the potency of the inhibitor can be depending on the energy of the transition state. Here, we report an efficient analysis of the noncovalent binding mode of a potent covalent proteasome inhibitor <b>3a</b> around the transition state by a combined use of the chemical approach, i.e., the cyclopropylic strain-based conformational restriction, and the computational docking approach. Furthermore, we calculated the binding energy of a series of salinosporamide derivatives in the predicted noncovalent complex around the transition state with the simulation model of proteasome constructed in this study, which was well correlated to their pIC₅₀. Thus, the proposed docking methods to predict the noncovalent binding mode around the transition state of covalent inhibitors will be helpful toward the development of covalent inhibitors

موسى بن محمد قاضي زاده الرومي. أشكال التأسيس

Numérisation effectuée à partir d'un document de substitution.Commentaire des Aškāl al-ta'sīs de Muḥammad ibn Ašraf al-Samarqandī. Titre au f. 2. Inc. (f. 2v) : الحمد لله الذي خلق كل شيء بقدر وقدر له ما يليق من أشكال وصور... وبعد فإن الهندسة مع متانة مسائلها Exp. (f. 50v) : وهذه الأشكال الخمسة الأخيرة من ثانية كتاب الأصول لأقليدس وليكن هذا آخر الكلام وقد تم الكتاب Copie achevée par ʿAbd al-Qādir ibn Muṣṭafā al-Ḥallāq le 12 šawwāl 1176 h. / 26 avril 1763.Cachet et marque du commanditaire de la copie : Muḥammad ʿĀrif, mudarris à Dār al-Sulṭana, Marque de possession de Muḥammad ibn Ḥusayn (?) (f. 1). Indication de prix : 15 piastres (f. 1). Marque à l'encre violette datée du 3 šaʿbān 1361 h. / 16 août 1942, au nom de Muḥammad al-Amīn ibn Muḥammad ʿAbd Allāh (f. 1v

Double Helices of a Pyridine-Appended Zinc Chlorophyll Derivative

Self-assembled structures formed from a pyridine-appended zinc chlorophyll derivative are reported. While the zinc complex forms cyclic oligomers in chloroform solution, as indicated by ¹H NMR studies (including diffusion-ordered spectroscopy), vapor pressure osmometry, and cold-spray ionization mass spectrometry, it forms double-stranded helical coordination polymers in the solid state, as revealed by single-crystal X-ray analysis

Double Helices of a Pyridine-Appended Zinc Chlorophyll Derivative

Self-assembled structures formed from a pyridine-appended zinc chlorophyll derivative are reported. While the zinc complex forms cyclic oligomers in chloroform solution, as indicated by ¹H NMR studies (including diffusion-ordered spectroscopy), vapor pressure osmometry, and cold-spray ionization mass spectrometry, it forms double-stranded helical coordination polymers in the solid state, as revealed by single-crystal X-ray analysis

Double Helices of a Pyridine-Appended Zinc Chlorophyll Derivative

Self-assembled structures formed from a pyridine-appended zinc chlorophyll derivative are reported. While the zinc complex forms cyclic oligomers in chloroform solution, as indicated by ¹H NMR studies (including diffusion-ordered spectroscopy), vapor pressure osmometry, and cold-spray ionization mass spectrometry, it forms double-stranded helical coordination polymers in the solid state, as revealed by single-crystal X-ray analysis