Studies of a nickel-based single-molecule magnet

A cyclic complex [Ni(12)(chp)(12)(O(2)CMe)(12)(thf)(6)(H(2)O)(6)] (1) has been synthesised and studied (chp=6-chloro-2-pyridonate). Complex 1 exhibits ferromagnetic exchange between the S=1 centres, giving an S=12 spin ground state. Detailed studies demonstrate that it is a single-molecule magnet with an energy barrier of approximately 10 K for reorientation of magnetisation. Resonant quantum tunnelling is also observed. The field between resonances allows accurate measurement of D, which is 0.067 K. Inelastic neutron scattering studies have allowed exchange parameters to be derived accurately, which was impossible from susceptibility data alone. Three exchange interactions are required: two ferromagnetic nearest neighbour interactions of approximately 11 and 2 cm(-1) and an anti-ferromagnetic next nearest neighbour interaction of -0.9 cm(-1).     

Effect of solvent composition on oxide morphology during flame spray pyrolysis of metal nitrates

The effect of solvent composition on particle formation during flame spray pyrolysis of inexpensive metal-nitrates has been investigated for alumina, iron oxide, cobalt oxide, zinc oxide and magnesium oxide. The as-prepared materials were characterized by electron microscopy, nitrogen adsorption, X-ray diffraction (XRD) and disc centrifugation (XDC). The influence of solvent parameters such as boiling point, combustion enthalpy and chemical reactivity on formation of either homogeneous nanoparticles by evaporation/nucleation/coagulation (gas-to-particle conversion) or large particles through precipitation and conversion within the sprayed droplets (droplet-to-particle conversion) is discussed. For Al(2)O(3), Fe(2)O(3), Co(3)O(4) and partly also MgO, the presence of a carboxylic acid in the FSP solution resulted in homogeneous nanoparticles. This is attributed to formation of volatile metal carboxylates in solution as evidenced by attenuated total reflectance spectroscopy (ATR). For ZnO and MgO rather homogeneous nanoparticles were formed regardless of solvent composition. For ZnO this is attributed to its relatively low dissociation temperature compared to other oxides. While for MgO this is traced to the high decomposition temperature of Mg(NO(3))(2) together with Mg(OH)(2)?MgO transformations. Cobalt oxide (Co(3)O(4)) nanoparticles made by FSP were not aggregated but rather loosely agglomerated as determined by the excellent agreement between XRD- and XDC-derived crystallite and particle sizes, respectively, pointing out the potential of FSP to make non-aggregated particles.     

Structure of the O‐Glycosylated Conopeptide CcTx from Conus consors Venom

The glycopeptide CcTx, isolated from the venom of the piscivorous cone snail Conus consors, belongs to the κA‐family of conopeptides. These toxins elicit excitotoxic responses in the prey by acting on voltage‐gated sodium channels. The structure of CcTx, a first in the κA‐family, has been determined by high‐resolution NMR spectroscopy together with the analysis of its O‐glycan at Ser7. A new type of glycopeptide O‐glycan core structure, here registered as core type 9, containing two terminal L ‐galactose units {α‐L ‐Galp‐(1→4)‐α‐D ‐GlcpNAc‐(1→6)‐[α‐L ‐Galp‐(1→2)‐β‐D ‐Galp‐(1→3)‐]α‐D ‐GalpNAc‐(1→O)}, is highlighted. A sequence comparison to other putative members of the κA‐family suggests that O‐linked glycosylation might be more common than previously thought. This observation alone underlines the requirement for more careful and in‐depth investigations into this type of post‐translational modification in conotoxins.     

Potent Inhibitors of Malarial Aspartic Proteases,the Plasmepsins,by Hydroformylation of Substituted 7‐Azanorbornenes

The increasing prevalence of multidrug‐resistant strains of the malarial parasite Plasmodium falciparum requires the urgent development of new therapeutic agents with novel modes of action. The vacuolar malarial aspartic proteases plasmepsin (PM) I, II, and IV are involved in hemoglobin degradation and play a central role in the growth and maturation of the parasite in the human host. We report the structure‐based design, synthesis, and in vitro evaluation of a new generation of PM inhibitors featuring a highly decorated 7‐azabicyclo[2.2.1]heptane core. While this protonated central core addresses the catalytic Asp dyad, three substituents bind to the flap, the S1/S3, and the S1′ pockets of the enzymes. A hydroformylation reaction is the key synthetic step for the introduction of the new vector reaching into the S1′ pocket. The configuration of the racemic ligands was confirmed by extensive NMR and X‐ray crystallographic analysis. In vitro biological assays revealed high potency of the new inhibitors against the three plasmepsins (IC₅₀ values down to 6 nM ) and good selectivity towards the closely related human cathepsins D and E. The occupancy of the S1′ pocket makes an essential contribution to the gain in binding affinity and selectivity, which is particularly large in the case of the PM IV enzyme. Designing non‐peptidic ligands for PM II is a valid route to generate compounds that inhibit the entire family of vacuolar plasmepsins.     

New Derivatives of 4-Aminobicyclo [2.2.2]octanones and -ols as Potential Antiprotozoals

New derivatives of 4-aminobicyclo[2.2.2]octanones and -ols were prepared. Their structures were established by means of NMR experiments. All new compounds were tested for their activities against Plasmodium falciparum and Trypanosoma b. rhodesiense. One of the bicyclooctanols showed promising antitrypanosomal activity.     

New 1,3-Thiazoles and 1,3-Thiazines from 1-Thiocarbamoylpyrazoles

New 1,3-thiazoles and 1,3-thiazines are prepared from 1-thiocarbamoyl-pyrazoles. The structures of the title compounds are established by a single crystal structure analysis. Furthermore, antiprotozoal activities of one compound have been determined.     

The future of post-genomic biology at the proteomic level: an outlook

Drug discovery and early-stage drugs and biomarkers development is a continuous adaptation and maturation process. The cycle of changes based on new findings is coupled with shifts in research priorities and make this part of pharmaceutical research a challenging endeavour. Over the last years, the emphasis on genomics has shifted to proteomics, the science of understanding how proteins translate gene information into function, and metabonomics, the science of small metabolites that are further apart from genomic projects. Proteomics describes the analysis of the protein complement of a biological sample with respect to temporal and spatial resolution. This technology is based on separation of complex protein mixtures by 2D gel-electrophoresis, in gel digest and mass spectrometric analysis of the protein fragments. Proteomics has been recently flanked by peptidomics, a new research direction aimed at the comprehensive analysis of small (1-20 kDa) polypeptides, thus covering the gap between proteomics and metabonomics. The refinement of peptidomics is based on an essential paradigm related to modularity and diversity. Peptides are a paramount example of how one single gene can release multiple functionalities. We can expect fast progress in understanding protein and peptide networks from a systems biology approach ending in the discovery of new peptide targets. However, the way from a complex sample to potential diagnostic and therapeutic targets will depend on technological developments and from the ability to discriminate true disease-related signals from false positive and negative signals, and the way from target discovery to target validation will not be short.