Stefan Jankowski

Synthesis and properties of ammonium ionic liquids with cyclohexyl substituent and dissolution of cellulose

We have synthesized alkyl(cyclohexyl)dimethylammonium bromides, formates and acetates, 2-methoxyacetates, 2-(2-methoxyethoxy)acetates, 2-[2-(2-methoxyethoxy)ethoxy]acetates, and 2-ethoxyacetates and assessed their ability to dissolve cellulose. Their physicochemical properties and microbiological activity were determined. Alkyl(cyclohexyl)dimethylammonium cation dimensions of alkyl groups are essential for cellulose solubility and are generally limited to butyl, hexyl, and octyl as effective substituents. In parallel, the alkyl group determines activity of the entire molecule against microbes. The molecules biological activity against microbes begins when a length of the alkyl substituent begins to block cellulose solubility. We present the computational model of the solubility mechanism, composed of an ensemble of two cellobiose units and (cyclohexyl)hexyldimethylammonium acetate.

The addition of dialkyl phosphites and diphenylphosphine oxide on the triple bond of dimethyl acetylenedicarboxylate under solvent-free and microwave conditions

The addition of dialkyl phosphites or diphenylphosphine oxide to the triple bond of dialkyl acetylenedicarboxylate may result in mono- and/or bisadducts. The ratio of the products may be influenced by the molar ratio of the reactants and the conditions (temperature of microwave irradiation and reaction time). Stereospecific (3)J(PP) couplings were utilized in the assignments to the meso and racemic forms of the bisadducts. The bis(dialkylphosphonyl)-succinates were formed as a mixture of the corresponding meso form and racemate, while bis(diphenylphosphinoyl)-succinate was obtained as a racemate. The P-31-(CH)-C-12-(CH)-C-13-P-31 spin system of bis(dialkylphosphonyl)-succinates was subjected to a detailed NMR analysis supported by simulation.

The structure of cyclolinopeptide A in chloroform refined by RDC measurements

Three‐dimensional structures of molecules traditionally assigned from nuclear Overhauser effects and vicinal coupling constants are recently complemented by measurements of residual dipolar couplings. Residual dipolar couplings measured in a stretched poly(dimethylsiloxane) gel were used to determine the structure of cyclolinopeptide A in chloroform solution at −50 °C. After structure refinement, conformational details of main cluster were discussed in relation to crystal and nuclear Overhauser effect derived structures. Copyright

Assessing the correlation between the degree of disc degeneration on the Pfirrmann scale and the metabolites identified in HR-MAS NMR spectroscopy

OBJECTIVE The objective of this study is to assess the correlation between the degree of degeneration of lumbar discs according to the Pfirrmann classification system and the concentrations of metabolites determined by means of 1H high-resolution magic angle spinning nuclear magnetic resonance (1H HR MAS NMR) spectroscopy. MATERIALS AND METHODS Twenty-six human intervertebral lumbar discs that were operated on due to degenerative disease were analyzed. Routine preoperative 1.5T, T2-weighed magnetic resonance (MR) images were used to classify the cases according to the Pfirrmann classification system. In all the cases, during microdiscectomy, the fragments of the annulus fibrosus and nucleus pulposus were harvested and their metabolic profile was examined by means of 1H HR MAS. The grades of disc degeneration on the Pfirrmann scale were correlated with the metabolite concentrations. RESULTS Spectral analyses of the intervertebral discs with Pfirrmann grades IV and V demonstrated significantly higher concentrations of creatine, glycine, hydroxyproline, alanine, leucine, valine, acetate, isoleucine, α,β-glucose, and myo-inositol, and a lower intensity of the N-acetyl peak of chondroitin sulfate, compared to the spectra with Pfirrmann grade III. CONCLUSION Our results demonstrate correlations between metabolite concentrations and the degree of lumbar disc degeneration assessed using the Pfirrmann grading system and provide another step toward the potential use of in vivo MR spectroscopy for investigation of biomarkers in lumbar disc degeneration.

Prediction of survival for patients with advanced colorectal cancer using 1H High‐resolution magic angle spinning nuclear MR spectroscopy

To evaluate whether the metabolic profiles of colorectal cancer specimens can be used for prediction of survival.

Synthesis and biological activity of cyclolinopeptide A analogues modified with γ 4 -bis(homo-phenylalanine)

Cyclolinopeptide A (CLA), an immunosuppressive nonapeptide derived from linen seeds, was modified with S or R-γ4-bis(homo-phenylalanine) in positions 3 or 4, or both 3 and 4. These modifications changed the flexibility of new analogues and distribution of intramolecular hydrogen bonds. Analogues 11 c(Pro1-Pro2-Phe3-S-γ4-hhPhe4-Leu5-Ile6-Ile7-Leu8-Val9), 13 c(Pro1-Pro2-S-γ4-hhPhe3-R-γ4-hhPhe4-Leu5-Ile6-Ile7-Leu8-Val9) and 15 c(Pro1-Pro2-R-γ4-hhPhe3-Phe4-Leu5-Ile6-Ile7-Leu8-Val9) existed as a mixture of stable cis/trans isomers of Pro-Pro peptide bond. The comparison of the relative spatial orientations in crystal state of the two carbonyl groups, neighboring γ-amino acids, revealed conformational similarities to α-peptides. The addition of two -CH2- groups in γ-amino acids led to a more rigid conformation, although a more flexible one was expected. A significant difference in the relative orientation of the carbonyl groups was found for cyclic γ-peptides with a dominance of an antiparallel arrangement. As carbonyl groups may be engaged in the interactions with plausible receptors through hydrogen bonds, a similar biological activity of the modified peptides was expected. Our biological studies showed that certain cyclic, but not the corresponding linear peptides, lowered the viability of peripheral blood mononuclear cells (PBMC) at 100μg/mL concentration. The proliferation of PBMC induced by phytohemagglutinin A (PHA) was strongly inhibited by cyclic peptides only, in a dose-dependant manner. On the other hand, lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α) production in whole blood cell cultures was inhibited by both linear and cyclic peptides. Peptide 15 c(Pro1-Pro2-R-γ4-hhPhe3-Phe4-Leu5-Ile6-Ile7-Leu8-Val9) blocked the expression of caspase-3, inhibited the expression of caspases-8 and -9 in 24h culture of Jurkat cells, and caused DNA fragmentation in these cells, as an indicator of apoptosis. Thus, we revealed a new mechanism of immunosuppressive action of a nonapeptide.

Crystal structure of (3R)-3-benzyl-4-[(tert-but­oxy­carbon­yl)amino]­butanoic acid

The characteristic feature of the title molecule, C16H23NO4, is the syn configuration of the partially double amide C—N bond [C—N—C—O torsion angle = −14.8 (2)°]. The crystal packing is determined by intermolecular O—H⋯O and N—H⋯O hydrogen bonds, which link the molecules into a double-chain structure extending along [010].

13C Kinetic Isotope Effect of the Pudovik Reaction

Abstract 13C kinetic isotope effect (KIE) was determined by means of 13C NMR for the carbonyl atom in 2-nitrobenzaldehyde in its reaction with 2H-2-oxo-5,5-dimethyl-4-phenyl-1,3,2-dioxaphosphorinane in acetonitrile at 25°C. The observed isotope effect k12/k13 = 1.0238 ± 0.0031 evidences that the formation of the P‒C bond in the Pudovik reaction catalyzed by triethylamine is less advanced than the π-bond breakage of the aldehyde carbonyl group. GRAPHICAL ABSTRACT