Thermogravimetric analysis of layered double hydroxides with chloramphenicol and salicylate in the interlayer space

The thermal behavior of the new inorganic-organic nanohybrid materials obtained by intercalation of chloramphenicol and salicylate into layered double hydroxides (LDHs) by direct synthesis method, anion exchange reaction and the reconstruction method was evaluated by dynamic thermogravimetric analysis in air, at heating rates of 5°C min⁻¹. The XRD patterns of the samples are characteristic for those of well crystallized solids with layered double hydroxide structures. The FTIR spectroscopy results show the presence of the organic compound within the network structure of the synthesized LDHs. The kinetic parameters (reaction order (n) apparent activation energy (E _a) and pre-exponential factor (lnA) were calculated by the Coats-Redfern method. The compensation effects were determined.     

Highly regioselective palladium-catalyzed methoxycarbonylation of styrene using chiral ferrocene- and biphosphole-based ligands

The methoxycarbonylation of styrene has been studied using Pd(OAc)₂/L/acid catalytic systems with L being chiral ferrocene- and biphosphole-based ligands. Good activities are obtained in mild conditions. Chemoselectivities and regioselectivities (up to 98% in favour of the branched isomer) are excellent but enantioselectivities remain moderate (ee up to 17%).     

Mössbauer effect and NMR study of amorphous Ni80−x Fe x B16Si4

The magnetic phase diagram of amorphous Ni₈₀? _x Fe _x B₁₆Si₄ was studied by de-magnetization measurement, by⁵⁷Fe-Mössbauer spectroscopy and pulsed spin echo NMR.     

Synthesis of N-benzyl-des-D-ring lamellarin K via an acyl-Claisen/Paal-Knorr approach

Lamellarin K is a complex pyrrole natural product and member of the lamellarin family – a group of natural products known for their potent biological activities, such as, antiproliferative activity and inhibition of P-gp mediated drug efflux pumps. We herein describe the synthesis of the N-benzyl-des-D ring analogue of lamellarin K using a route that centres on an acyl-Claisen reaction to eventually prepare a highly-functionalised 1-aryl-4-methyl-1,4-diketone. Paal-Knorr pyrrole formation using this diketone undergoes auto-oxidation to give a fully-substituted 5-formyl pyrrole which was converted into the natural lactone B ring. Antiproliferative testing of the N-benzyl-des-D ring analogue gave an IC₅₀ of 2.63 μM against the MDA-MB-231 breast cancer cell line.     

Recycling of pipecoloxylidide via racemization

A method for the racemization of pipecoloxylidide with a ruthenium catalyst has been developed. This racemization method can be implemented in an integrated process that combines the separation of two enantiomers with racemization of the undesired enantiomer.     

A simple method for the oxidation of α-amino acid esters to α-oximino esters

Magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) was found to be an effective reagent for the oxidation of various α-amino acid esters to the corresponding α-oximino acid esters. This transformation could be completed under mild conditions within 2.5 h using 1.1 equiv of MMPP in THF. Clean oximino esters were obtained after quenching and extracting the reaction from sodium thiosulfate solution. The O-phosphorylated derivative of 2-oximinoglutarate exhibited slow binding inhibitory potency for the metallopeptidase prostate-specific membrane antigen (PSMA) with an IC₅₀ value of 58 nM.     

The possible production of natural flavours by amino acid degradation

Abstract  

This work describes the degradation of phenylalanine and tryptophane catalysed by their complexes with Fe(II), Co(II), and Cu(II). The influences of the central atom and of the reaction conditions on the degradation of the amino acids were observed. The necessary condition of the degradation is the possibility of a redox reaction on the central atom between M(II) and M(III). Moreover, the coordination sphere of the central cation of the transition metal must not be sterically shielded. The necessary conditions are fulfilled only in the Fe(II) complexes. The degradation is strictly anaerobic because due to the influence of oxygen, an irreversible oxidation of Fe(II) to Fe(III) proceeds. This reaction results in 5-hydroxy-1H-indol instead of the mixture of the degradation products, such as benzaldehyde, phenylacetaldehyde, and phenylacetic acid. The influence of the temperature on the catabolism is very important because the reaction accelerates with temperature increase. The phenylalanine anion acts as a reducing agent, and Fe(II) is spontaneously reduced to Fe(0).     

Magnetic particles functionalized with PAMAM-dendrimers and antibodies: a new system for an ELISA method able to detect Ara h3/4 peanut allergen in foods

An innovative enzyme-linked immunosorbent assay (ELISA) format based on antibody-coated magnetic micro-particles (MPs) for the sensitive detection of Ara h3/4 allergen in food is described. The immunosupport is suspended in the incubation solutions and the MPs with the captured allergen can be easily harvested on a magnet, separated from the solutions, and washed using an easy-to-use, fast and selective approach that allows its detection and quantification. Two differently coated MPs, ProteinA-Pn-b and MP-NH₂-PAMAM G 1.5 -Pn-b immunosupports, were tested. The functionalization of the MPs with PAMAM-sodium carboxylate dendrimers elicits a major stability on the immunoglobulin activity resulting in a threefold enhancement of the analytical sensitivity for the assay with respect to a ProteinA immobilization. Validation was carried out on two different matrices: corn flakes and biscuits. In the case of MP-NH₂-PAMAM G 1.5 -Pn-b immunosupport, limit of detection was found to be 0.2 mg peanuts/kg matrix in both matrices; the linear response range was demonstrated from 2.5 to 15 mg peanuts/kg matrix by performing statistical tests (homoscedasticity and Mandel fitting tests). Good accuracy and recovery (>80 ± 2%) were obtained. Different food samples were tested and the results were compared with those obtained with a commercially available ELISA kit. The results obtained in this work demonstrated the applicability of the immunomagnetic ELISA methods on real samples and the possibility to perform the assay with significantly reduced reagent and sample consumption.     

Effects of Lactobacillus rhamnosus on zebrafish oocyte maturation: an FTIR imaging and biochemical analysis

The aim of this study was to verify the effects of probiotic Lactobacillus rhamnosus on zebrafish oocyte maturation using FPA (focal plane array) FTIR imaging together with specific biochemical assays (SDS-PAGE, real-time PCR and enzymatic assay). Oocyte growth is prevalently due to a vitellogenic process which consists of the hepatic synthesis of vitellogenin and its selective uptake during maturation. The administration of L. rhamnosus IMC 501 for 10 days induced chemical changes to oocyte composition, promoting the maturation process. Some interesting biochemical features, linked to protein secondary structure (amide I band) and to phospholipidic and glucidic patterns, were detailed by vibrational analysis. The spectroscopic results were supported by the early increase of the lysosomal enzyme involved in the final oocyte maturation, the cathepsin L. This enzyme increases during follicle maturation, with the highest levels in class IV oocytes. In treated females, class III oocytes showed higher cathepsin L gene expression and enzymatic activity, with levels comparable to class IV oocytes isolated from controls; this can be related to the proteolytic cleavage of the higher molecular mass yolk protein components, as evidenced by SDS-PAGE.