The Genus Cladosporium: A Rich Source of Diverse and Bioactive Natural Compounds

Fungi are renowned as one of the most fruitful sources of chemodiversity and for their ubiquitous occurrence. Among the many taxonomic groupings considered for the implications deriving from their biosynthetic aptitudes, the genus Cladosporium stands out as one of the most common in indoor environments. A better understanding of the impact of these fungi on human health and activities is clearly based on the improvement of our knowledge of the structural aspects and biological properties of their secondary metabolites, which are reviewed in the present paper.     

Controlled density patterning of tolylterpyridine-tagged oligonucleotides

An efficient surface anchoring strategy of tolylterpyridine-tagged DNA single strands (ssDNA-ttpy) synthesized on gold electrodes is reported. The method is based on exchange reactions between Fe(II)bis-terpyridine complexed SAMs and ssDNA-ttpy, and allows efficient hybrydization of the cDNA strands. Moreover, by using low-current focused ion beam lithography, micropatterned arrays are obtained, homogeneously covered with ssDNA-ttpy. The surface adsorption kinetics of ssDNA-ttpy, as well as its hybridization efficiency, was monitored by in situ quartz crystal microbalance with dissipation monitoring (QCM-D) technique. The effective confinement of the ssDNA-ttpy at the micrometer level has been monitored by time of flight secondary ion mass spectrometry (ToF-SIMS) and ellipsometric surface imaging experiments, providing laterally resolved chemical and topographic mapping.     

Synthesis and characterization of a colloidal novel folic acid?C??-cyclodextrin conjugate for targeted drug delivery

A novel folic acid?C??-cyclodextrin (??-CD) conjugate was synthesized and preliminarily characterized by ¹H NMR, ESI-MS, and MALDI-MS. ¹H NMR shows the presence of ??- and ??-conjugates which are generated by ??-CD linkage in turn with both carboxylic functions of folic acid. Moreover ROESY evidences supramolecular interactions between the benzene ring of the folic acid and the ??-CD cavity. DOSY suggests that ethylenediamine derived ??-CD?Cfolic acid forms a colloidal dispersion difficult to purify from free folic acid. An analysis of self-diffusion coefficient (D_s) of the three species (??-, ??-conjugates, and free folic acid) and relaxation times (T₁ and T₂) is reported to tentatively explain the colloidal behaviour of the new species in an aqueous solution.     

Review: applications of mass spectrometry techniques in the investigation of milk proteome

The introduction of "soft" desorption/ionization methods such as electrospray ionization and matrix-assisted laser desorption/ionization has determined a breakthrough in the application of mass spectrometry to the structural analysis of proteins. The contemporary advancement of bioinformatics, together with the possibility to combine these mass spectrometric methods with electrophoretic or chromatographic separation techniques has opened up the new field of proteome analysis and, more generally, has established these approaches as indispensable tools for protein and peptide analysis in complex mixtures, such as milk and milk- derived foods. Here, a necessarily not exhaustive series of current applications of mass spectrometry-based techniques for the characterization of milk proteins will be summarized. These include the characterization of milk protein polymorphism, determination of the structural modifications induced on milk proteins by industrial processes, investigation of milk adulterations and characterization of milk allergens.     

Free energy evaluation of the p53-Mdm2 complex from unbinding work measured by dynamic force spectroscopy

The complex between the tumor suppressor p53 and its down-regulator Mdm2 has been studied by dynamic force spectroscopy and the unbinding data have been analyzed in the framework of the Jarzynski theoretical approach. Accordingly, the unbinding equilibrium free energy has been determined from the work done along several non-equilibrium paths from the bound to the unbound state in the single molecule regime. An unbinding free energy of -8.4 kcal mol(-1) has been found for the complex; such a value is in a good agreement with that measured both in the bulk by isothermal titration calorimetry and that obtained from theoretical computing at the single molecule level. The determination of the unbinding free energy, together with the knowledge of the dissociation rate constant and energy barrier width, as previously obtained by dynamic force spectroscopy, adds rewarding insights on the energy landscape for this complex which is currently at the focus of anticancer drug design.     

Guest-accelerated molecular rotor

A molecular rotor was designed in which the rate of rotation is accelerated by guest complexation. The binding of an acetate guest to the urea groups lowers the barrier of the adjacent C(aryl)-N(imide) bond by 2 to 4 kcal/mol. This behavior is in contrast to most molecular rotors in which guest complexation slows rotation.     

Field-amplified sample injection combined with pressure-assisted capillary electrophoresis UV detection for the simultaneous analysis of allantoin, uric acid, and malondialdehyde in human plasma

The allantoin/uric acid (All/UA) ratio and malondialdehyde (MDA) plasma levels have been proposed as important markers for monitoring oxidation triggered by the action of free radicals (FR). Here, we describe an easy field amplified sample injection capillary electrophoresis method with UV detection for the separation and quantification of All, UA, and free MDA in human plasma. The plasma samples were simply filtered through centrifugation membrane tubes for protein elimination and directly injected on a capillary without complex cleanup and/or sample derivatization procedures. The use of a run buffer composed of 300 mmol/L sodium borate at pH 10 with 50 mmol/L of N-methyl-d-glucamine and an overimposed pressure/voltage of 0.1 psi during the electrophoretic run allows basline resolution of the analytes within 17 min. The electrokinetic injection allows a detection limit of 15 nmol/L for All, 20 nmol/L for UA and 10 nmol/L for MDA in a plasma sample, thus significantly improving the LOD of previous described methods based on capillary electrophoresis. Precision tests indicate a good repeatability of our method both for migration times (CV = 1.85%) and areas (CV = 2.87%). Moreover, a good reproducibility of intra- and inter-assay tests was obtained (CV = 4.63% and CV = 6.59% respectively). The suitability of the method was tested by measuring analyte levels in 40 healthy volunteers.     

Measurement of carnosine, homocarnosine and anserine by FASI capillary electrophoresis UV detection: applications on biological samples

A field amplified sample injection (FASI) capillary electrophoresis method with UV detection was developed for the separation and detection of carnosine-related peptides carnosine (Car), anserine (Ans) and homocarnosine (Hcar). The imidazole dipeptides were baseline-separated within 10 min by using 50 mmol/L Tris phosphate pH 2.2 as running buffer. The samples were diluted in water and directly injected on the capillary without complex cleanup and/or sample derivatization procedures. Using the electrokinetic injection, a sensitivity improvement of about 500-fold was achieved without any loss of separation efficiency if compared to the conventional sample injection. The detection limits for carnosine, anserine, and homocarnosine were between 0.4 and 0.5 nmol/L, thus improving of 10-100-fold the LOD of previous described methods based on laser induced fluorescence or chemiluminescence detection. This method has been applied to the analysis of homogenized rat tissue (heart, muscle and brain) and human cerebrospinal fluid (CSF).     

Cation environment of BaCeO3-based protonic conductors II: new computational models

Quantum chemical calculations have been carried out to simulate Y-doped BaCeO(3) derivatives. Hartree-Fock energy functional was used to study octahedral site environments embedded in a Pmcn orthorhombic framework, showing local arrangement characterized by Ce-O-Ce, Ce-O-Y, and Y-O-Y (Z-O-Ξ) configurations and including or not hydrogen close to the moieties encompassing those configurations. The latter are, in fact, representative of - and, in our modeling approach, were treated as - local arrangements that could be found in Y:BaCeO(3)-doped materials. The geometrical optimizations performed on the structural models and a detailed orbital analysis of these systems allowed us to confirm and deepen new interpretations, concerning experimental findings already reported in the literature. In particular, the bimodal distribution characterizing the Y-O first coordination shell, found by EXAFS analysis, could be attributed to a local clustering of Y atoms showing characteristic Y-O-Y arrangements. Moreover, the local charge analysis, characterizing the models containing or not hydrogen atoms, showed that the moving protons are able to dynamically change the properties of their near environment, in any case, leaving unaltered the global protonic conduction features of the material, irrespective of the kind of cation in a given Z-O-Ξ moiety.     

Analysis of the reactivity on the c7h6 potential energy surface

The reactivity and decomposition kinetics on the C(7)H(6) potential energy surface (PES) were investigated, determining structures of stationary points at the B3LYP/6-31+G(d,p) level and energies at the CCSD(T)/cc-pVTZ level with extension to the complete basis set limit. For the reactions characterized by a significant multireference character, the energies were calculated at the CASPT2/cc-pVTZ level. The portion of the PES investigated consisted of 27 wells connected by 39 saddle points. Of the 27 wells, 16 can be accessed through transition states having activation energies smaller than the dissociation threshold. In agreement with previous theoretical studies, it was found that the main interconversion channel takes place on the singlet PES and connects phenylcarbene, cycloheptatetrane, spiroheptatriene, fulvenallene, and three ethynylcyclopentadiene isomers. Two new mechanisms are proposed for the formation of 5-ethynylcyclopentadiene and for the conversion of spiroheptatriene to fulvenallene. The unimolecular decomposition kinetics was thoroughly investigated. It was found that the fastest high pressure decomposition channel, at the temperatures at which C(7)H(6) undergoes unimolecular decomposition (1500--2000 K), leads to the formation of cyclopentadienylidene and acetylene. The rate of crossing from the singlet to the triplet PES may affect considerably this reaction channel, as it is formally spin forbidden. The alternative pathway, which is the decomposition to fulvenallenyl, is however only a factor of 2--3 slower and significantly less activated (82 vs 96 kcal/mol).