A series of water-soluble cationic chitosan derivatives were prepared by chemoselective functionalization at the amino group of five different parent chitosans having varying degrees of acetylation and molecular weight. The quaternary moieties were introduced at different alkyl spacer lengths from the polymer backbone (C-0, C-2 and C-6) with the aid of 3,6-di-O-tert-butyldimethylsilyl protection of the chitosan backbone, thus allowing full (100%) substitution of the free amino groups. All of the derivatives were characterized using 1H-NMR, 1H-1H COSY and FT-IR spectroscopy, while molecular weight was determined by GPC. Antibacterial activity was investigated against Gram positive S. aureus and Gram negative E. coli. The relationship between structure and activity/toxicity was defined, considering the effect of the cationic group’s structure and its distance from the polymer backbone, as well as the degree of acetylation within a molecular weight range of 7–23 kDa for the final compounds. The N,N,N-trimethyl chitosan with 100% quaternization showed the highest antibacterial activity with moderate cytotoxicity, while increasing the spacer length reduced the activity. Trimethylammoniumyl quaternary ammonium moieties contributed more to activity than 1-pyridiniumyl moieties. In general, no trend in the antibacterial activity of the compounds with increasing molecular weight or degree of acetylation up to 34% was observed.

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The molecular structure of 1-methyl-1-silacyclohexane 3 has been determined by gas electron diffraction (GED). The conformational preference of the methyl group was studied experimentally in the gas phase (GED) and in solution (low-temperature (13)C NMR) and by quantum chemical calculations (HF, MP2, and B3LYP with 6-31G basis sets and mPW1PW91/6-311G(2df,p)). Both experimental methods result in a preference of the equatorial position of the methyl group, 68(7)% in the gas phase at 298 K and 74(1)% in solution at 110 K. The calculations predict 68-73% equatorial conformer at room temperature. From coalescence temperatures, Gibbs free energies of activation for ring inversion DeltaG++ (eq --> ax) = 5.81(18) and DeltaG++ (ax --> eq) = 5.56(18) kcal mol(-1) were derived. The calculated values for DeltaG++ (eq --> ax) are 5.92 (B3LYP) and 5.84 kcal mol(-1) (mPW1PW91).

A fast, one-step gas chromatographic method was developed to analyze trimethylsilyl (TMS) derivatives of sugars, fruit acids, and ascorbic acid in sea buckthorn (Hippohaë rhamnoides L.) berries. The method was applied to berry press juice of sea buckthorn of different origins grown in Finland during the 2003 and 2004 seasons. The method gave reliable results for D-fructose, D-glucose, ethyl-D-glucose, and malic, quinic, and ascorbic acids, which are the major sugars and acids in sea buckthorn juice. For the first time in sea buckthorn and evidently in any berry, the presence of ethyl beta-D-glucopyranoside is reported. The structure of ethyl glucose was verified by high-performance liquid chromatography (HPLC), gas chromatography (GC), MS, and NMR analyses of both the isolated and the synthesized compounds. In the GC method, vitamin C was analyzed as ascorbic acid only, and dehydroascorbic acid was thus not taken into account.

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Background Insect bite hypersensitivity (IBH) is the most common seasonal pruritic allergic dermatitis of horses occurring upon insect bites. In recent years, a major role for IL‐31 in allergic pruritus of humans, monkeys, dogs, and mice was acknowledged. Here, we investigate the role of IL‐31 in IBH of horses and developed a therapeutic vaccine against equine IL‐31 (eIL‐31). Methods IL‐31 levels were quantified in allergen‐stimulated peripheral blood mononuclear cells (PBMCs) and skin punch biopsies of IBH lesions and healthy skin from IBH‐affected and healthy horses. The vaccine consisted of eIL‐31 covalently coupled to a virus‐like particle (VLP) derived from cucumber mosaic virus containing a tetanus toxoid universal T‐cell epitope (CuMVTT). Eighteen IBH‐affected horses were recruited and immunized with 300 μg of eIL‐31‐CuMVTT vaccine or placebo and IBH severity score was recorded. Results IL‐31 was increased in PBMCs and exclusively detectable in skin lesions of IBH‐affected horses. Vaccination against eIL‐31 reduced delta clinical scores when compared to previous untreated IBH season of the same horses and to placebo‐treated horses in the same year. The vaccine was well tolerated without safety concerns throughout the study. Conclusion TH2‐derived IL‐31 is involved in IBH pathology and accordingly the immunotherapeutic vaccination approach targeting IL‐31 alleviated clinical scores in affected horses.

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The molecular structures of axial and equatorial conformers of 1-fluorosilacyclohexane, C 5 H 10 SiHF, as well as the thermodynamic equilibrium between these species were investigated by means of gas electron diffraction (GED), dynamic nuclear magnetic resonance, temperature-dependent Raman spectroscopy, and quantum chemical calculations (MP2, DFT, and composite methods). According to GED, the compound exists in the gas phase as a mixture of two conformers possessing the chair conformation of the six-membered ring and C s symmetry and differing in the axial or equatorial position of the Si-F bond (axial ) 63( 8) mol %/equatorial ) 37(8) mol %) at T ) 293 K, corresponding to an A value of -0.31(20) kcal mol -1 . Density functional theory (DFT) calculations were employed to obtain the minimal energy path of the conformational inversion. The MP2, G3B3, and CBS-QB3 methods were also employed to calculate the equilibrium geometries and energies of the local minima in the gas phase and in solution. The gas-phase results are in good agreement with the experiment, whereas a combined PCM/IPCM(B3LYP/6-311G(d)) approach overestimates the stabilization of the axial conformer by 0.3-0.4 kcal mol -1 in solution at 112 K. Temperature-dependent Raman spectroscopy in the temperature ranges of 210-300 K (neat liquid), 120-300 K (pentane solution), and 200-293 K (dichloromethane solution) also indicates that the axial conformer is favored over the equatorial one by 0.25(5), 0.22(5), and 0.28(5) kcal mol -1 (∆H values), respectively.