Monitoring and fast detection of mycotoxin-producing fungi based on headspace solid-phase microextraction and headspace sorptive extraction of the volatile metabolites

Solid phase microextraction in combination with capillary GC-MS was used as monitoring technique for the collection and detection of the fungal volatile metabolite (+)-aristolochene by sporulated surface cultures of Penicillium roqueforti. A comparison was made between different toxigenic and nontoxigenic strains of P. roqueforti. Different growth conditions and media, such as malt extract agar, potato dextrose agar and sabouraud dextrose agar were compared. Whereas toxigenic strains produced large amounts of (+)-aristolochene, beta-elemene, valencene and germacrene A, nontoxigenic P. roqueforti strains showed a remarkably different headspace profile, in which ethyl-2-hexenoate, E-beta-caryophyllene, aromadendrene and beta-patchoulene were the predominant volatiles, apart from other sesquiterpene hydrocarbons present at lower concentrations. Stir bar sorptive extraction, was also applied in the headspace sampling mode, i.e. headspace sorptive extraction (HSSE) for the enrichment of fungal volatiles from sporulated surface cultures to differentiate between toxigenic and nontoxigenic fungi. Hence, it can be concluded that headspace analysis of volatile fungal metabolites by SPME and HSSE in combination with capillary GC-MS is a suitable monitoring technique for the fast detection of mycotoxin producing fungi.     

First example of a tetra-carboxylate bridged dimanganese species

The compound [Mn(tda)(bipy)] (tda = S(CH2COO)2(2-)) features the first structurally characterized tetra-carboxylate dimanganese antiferromagnetic system with 'copper acetate' core; the binuclear units, completed by bipyridine chelates, are doubly chained by the tda anions that adopt an unprecedented mu,mu'-eta1,eta1,eta1,eta1 coordination mode.     

Phenotype and in vitro function of mature MDDC generated from cryopreserved PBMC of cancer patients are equivalent to those from healthy donors

Background  

Monocyte-derived-dendritic-cells (MDDC) are the major DC type used in vaccine-based clinical studies for a variety of cancers. In order to assess whether in vitro differentiated MDDC from cryopreserved PBMC of cancer patients are functionally distinct from those of healthy donors, we compared these cells for their expression of co-stimulatory and functional markers. In addition, the effect of cryopreservation of PBMC precursors on the quality of MDDC was also evaluated using samples from healthy donors.     

A density functional theory study on the electrocyclization of 1,2,4,6-heptatetraene analogues: converting a pericyclic to a pseudopericyclic reaction

A comprehensive B3LYP/6-31+G* study on the electrocyclization of 1,2,4,6-heptatetraene analogues was conducted. Starting from the cyclization of (2Z)-2,4,5-hexatrienal, a pericyclic disrotatory process favored by the assistance of a electron lone pair, we incorporated small modifications in its molecular structure to obtain a truly pseudopericyclic process. To this purpose electronegative atoms (fluorine and nitrogen) were added to give a more electrophilic character on the carbon atom which is attacked by the electron lone pair of the oxygen atom. The complete pathway for each reaction was determined, and changes in magnetic properties were monitored with a view to estimating the aromatization associated with each process. This information, together with the energetic and structural results, allowed us to classify the reactions as pseudopericyclic or pericyclic. Among all studied reactions only one was a truly pseudopericyclic process and another was a borderline case. The features of this unequivocally pseudopericyclic case were analyzed in depth.     

Theoretical studies on the tautomerism of 1,5,6,7-tetrahydro-4H-indazol-4-ones

Computational studies on three tautomeric forms of four 1,5,6,7-tetrahydro- 4H-indazol-4-one derivatives: 1,5,6,7-tetrahydro-4H-indazol-4-one (1), 6,6-dimethyl- 1,5,6,7-tetrahydro-4H-indazol-4-one (2), 3-methyl-1,5,6,7-tetrahydro-4H-indazol-4-one (3) and 3,6,6-trimethyl-1,5,6,7-tetrahydro-4H-indazol-4-one (4), have been performed at different levels, ranging from semiempirical AM1, ab initio Hartree-Fock HF/6-31G* and HF/6-31G** to B3LYP/6-31G** density functional calculations. These calculations have been used to establish the most stable tautomer, which in all cases was in agreement with the experimental data.     

High-performance liquid chromatographic separation of rolipram, bupivacaine and omeprazole using a tartardiamide-based stationary phase influence of flow rate and temperature on the enantioseparation

Chromatographic separation of the chiral drugs rolipram, bupivacaine and omeprazole on a tartardiamide-based stationary phase commercially named Kromasil CHI-TBB is shown in this work. The effect of temperature on the chromatographic separation of the chiral drugs using the Kromasil CHI-TBB stationary phase was determined quantitatively so as to contribute toward the design for the racemic mixtures of the named compound by using chiral columns. A decrease in the retention and selectivity factors was observed, when the column temperature increased. Van't Hoff plots provided the thermodynamic data. The variation of the thermodynamic parameters enthalpy and entropy are clearly negative meaning that the separation is enthalpy controlled.     

Water adsorption on and desorption from crystalline copolymers of vinylidene fluoride with trifluoroethylene

Water adsorption and absorption on crystalline polyvinylidene fluoride with 30% trifluoroethylene, P(VDF-TrFE, 70:30), was examined by thermal desorption spectroscopy. Two distinctly different water adsorption sites are identified: one adsorbed species that resembles ice and another species that interacts more strongly with the polymer thin film. The existence of the latter species is consistent with X-ray diffraction studies of water absorbed into the bulk of copolymers of polyvinylidene fluoride with trifluoroethylene crystalline thin films. There are strong steric effects observed in the angle-resolved thermal desorption that may be a result of the large polymer thin film surface dipoles.     

delta-Lactone from Oedogonium capillare and their effects on rat ileum

Antispasmodic activity-guided fractionation together with chemical analysis led to the isolation of one novel delta-lactone named oedogonolide from Oedogonium capillare. Identification was based on spectroscopic methods. The oedogonolide produces a significant antispasmodic effect on the contractions of the rat ileum induced by acetylcholine, histamine and barium chloride.     

Mono- and diboronates derived from tridentate ONO ligands and arylboronic acids

The syntheses of eight [4.3.0] heterobicyclic boronates containing a N → B coordinative bond are described. The monomeric compounds were prepared by reaction of arylboronic acids with a tridentate ligand having the ONO donor set of atoms. It was shown that substituents at the para-position of the B-phenyl moiety transmit electronic effects to the CN bond which in turn is polarized by formation of the N → B coordination bond. At the same time, related tridentate ligands were also reacted with 1,4-benzenediboronic acid in order to prepare benzene diboron complexes. The structure of this type of compounds was confirmed by X-ray analysis for one of the derivatives.