Molecularly imprinted polymer solid-phase extraction for detection of zearalenone in cereal sample extracts

The aim of this work was to develop a method for the clean-up and preconcentration of zearalenone from corn and wheat samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). Cereal samples were extracted with acetonitrile/water (75:25, v/v) and the extract was diluted with water and applied to an AFFINIMIP ZON MIP-SPE column. The column was then washed to eliminate the interferences and zearalenone was eluted with methanol and quantified using HPLC with fluorescence detection (lambda(exc)=275/lambda(em)=450 nm). The precision and accuracy of the method were satisfactory for both cereals at the different fortification levels tested and it gave recoveries between 82 and 87% (RSDr 2.5-6.2%, n=3) and 86 and 90% (RSDr 0.9-6.8%, n=3) for wheat and maize, respectively. MIP-SPE column capacity was determined to be not less than 6.6 microg of zearalenone and to be at least four times higher than that of immunoaffinity column (IAC). The application of AFFINIMIP ZON molecularly imprinted polymer as a selective sorbent material for detection of zearalenone fulfilled the method performance criteria required by the Commission Regulation (EC) No. 401/2006, demonstrating the suitability of the technique for the control of zearalenone in cereal samples.

Sugar derived hexacoordinated phosphates: Chiral anionic auxiliaries with general asymmetric efficiency

Mannose-derived hexacoordinated phosphate anions, prepared in as few as two steps from methyl-alpha-D-mannopyranoside and tris(dimethylamino)phosphine, are chiral anionic auxiliaries with broad asymmetric efficiency. These chemically robust anions are effective NMR chiral solvating agents and efficient asymmetry-inducers, able to control the configuration of conformationally labile C2-symmetric monomethinium cations (organic, helical, charge 1+, P or M enantiomers) and D3-symmetric iron(II) trisdiimine complexes (metallo-organic, octahedral, charge 2+, Delta or Lambda enantiomers). Diastereomeric control with often unmatched selective levels was achieved with the help of mannopyranoside backbone of the anions and the substituents on the [1,3]dioxane ring that play a key role in the recognition process, something not obvious at first sight.

Biphasic Enantioselective Olefin Epoxidation Using Tropos Dibenzoazepinium Catalysts

Several novel chiral iminium TRISPHAT [tris(tetrachlorobenzenediolato)phosphate(V)] salts combining a diphenylazepinium core, chiral exocyclic appendages, and lipophilic counterions have been prepared and tested in biphasic enantioselective olefin epoxidation conditions. Interestingly, the iminium salts derived from commercially available (S)- or (R)-1,2,2-trimethylpropylamine can display efficiency similar to those made from L-acetonamine. Variable-temperature NMR spectroscopy (VT-NMR) and circular dichroism (CD) experiments were performed in search of a correlation between good enantioselectivity in the products and high diastereomeric control of the biphenyl axial chirality of the catalysts.

Inhibitory effects and spectral interactions of isomeric methoxyindazoles on recombinant nitric oxide synthases

A series of isomeric methoxyindazoles has been evaluated as inhibitors of purified recombinant neuronal, inducible, and endothelial nitric oxide synthases (NOS). 7-Methoxyindazole (7-MI) was the most active compound of this series and displayed selectivity toward the constitutive neuronal (NOS I) and endothelial (NOS III) NOS isoforms, the inducible NOS II being almost insensitive to this inhibitor. 6-, 5-, and 4-Methoxyindazoles were almost inactive against all three NOS isoforms. Inhibition of NO and citrulline formation catalyzed by neuronal NOS in the presence of 7-MI appeared to be competitive versus both substrate L-arginine (L-arg) and (6R)-5,6,7,8-tetrahydrobiopterin (BH(4)) cofactor. 7-MI only slightly inhibited NADPH oxidase activity and was inactive against the cytochrome c (cyt c) reductase activity of neuronal NOS at concentrations up to 100-fold higher than its IC(50) value for inhibition of citrulline formation. UV/Vis and EPR studies indicated that 7-MI interacts with the oxygenase domain of neuronal NOS (NOS I(oxy)) in an identical manner but with a much lower affinity than 7-nitroindazole (7-NI). These results demonstrate that an indazole derivative bearing an electron-rich substituent in the 7-position is also a NOS I inhibitor and that such a compound presents strong similarities with the mechanism of inhibition of 7-NI.

Mannose derived hexacoordinated phosphate--a generally efficient chiral anion for asymmetric applications

Mannose derived hexacoordinated phosphate--prepared in two steps from methyl-alpha-D-mannopyranoside--is a chiral anionic auxiliary with broad asymmetric efficiency.

Preparation of alpha, beta-acetylenic ketones by catalytic heterogeneous oxidation of alkynes

Covalent grafting of iron phthalocyanines onto silica affords active catalysts for selective oxidation of alkynes and propargylic alcohols to alpha, beta-acetylenic ketones, highly valuable precursors in the preparation of fine chemicals.