Analysis of native carotenoid composition of sweet bell peppers by serially coupled C30 columns

Serial coupled columns reversed-phase separations in high-performance liquid chromatography can be a useful tool for the analysis of complex real samples. The great difficulties found when analyzing complex carotenoid samples, due to the high natural variability of these compounds, as well as to the presence of carotenoid esters, are well documented. In the present contribution, the applicability of connecting two C30 columns to increase significantly the separation power, resolution and peak capacity for the analysis of carotenoids in a complex carotenoid sample, like sweet bell peppers, has been shown for the first time. By using LC coupled to PDA/APCI-MS detectors, 56 different carotenoids have been detected in red sweet bell peppers. By using two serial coupled C30 columns a peak capacity of 95.4 was obtained, compared with 73 achieved using a single column. Moreover, resolution greatly improved between different critical peaks when using two serial coupled C30 columns, compared with a single column. Interestingly, free carotenoids, mono-esters and diesters were quantitatively equally represented (around 33% for each different class) in red sweet bell pepper, showing, therefore, a value for the ratio of mono-esters/diesters of around 1, which could be considered a parameter of typicality. Free beta-carotene (12.6%), capsanthin-C14:0 (8.4%), and capsanthin-C12:0-C14:0 (8.9%) were the most abundant carotenoids in the three different classes of red sweet bell pepper. No carotenoid esters were detected in either yellow or green sweet bell peppers. The application of such methodology in the analysis of other complex carotenoid matrices could be a future objective of research.     

Carotenoids from the ripening bacterium Brevibacterium linens impart color to the rind of the French cheese,Fourme de Montbrison (PDO)

Abstract

Rind color of some high-value PDO cheeses is related to the presence of carotenoids, but little is known about the structure of the pigmented compounds and their origin. Our objective was to describe the carotenoids extracted from the rind of a French cheese, Fourme de Montbrison, and to compare them with the pigments produced by a bacterial strain used as an adjunct culture in the cheese ripening process. Eleven carotenoids were detected in the cheese rinds or in the biomass of Brevibacterium linens. Most of the carotenoids from the rinds belonged to the aryl (aromatic) carotenoid family, including hydroxylated and non-hydroxylated isorenieratene. Chlorobactene, a carotenoid rarely found in food products, was also detected. Agelaxanthin A was identified in the cheese rinds as well as in the B. linens biomass. Occurrence of this compound was previously described in only one scientific publication, where it was isolated from the sponge Agela schmidtii.     

Thermal decomposition of metal complexes. IX. Polynuclear complexes of lanthanide(III) ions with a metal schiff base complex as ligand

The kinetics of the thermal decomposition of some binuclear and trinuclear complexes of lanthanide(III) ions with the ligand N, N′-propilenbis (salicylideniminato) Cu(II) were studied under high vacuum (2 × 10⁻⁶ mm Hg) and in isothermal conditions. The trend of E^*_a values of the heavier lanthanoid complexes does not fit a reliable relation with the ionic radius, while the lighter lanthanoid complexes parallel those observed in other already studied lanthanoid derivatives.     

Ligand exchange chiral separations by cyclodextrin derivatives in capillary electrophoresis

A beta-cyclodextrin substituted by an imidazole-bound histamine (CDmh) was successfully used to separate underivatised tryptophan racemate in capillary electrophoresis in the presence of copper(II) ion by the ligand exchange mechanism. To the best of our knowledge, this is the first example of a cyclodextrin derivative behaving as the first coordination sphere ligand in the complex added to the background electrolyte (BGE).     

Suppression of plasma turbulence during optimized shear configurations in JET

Correlation of density turbulence suppression and reduced plasma transport is observed in the internal transport barrier (ITB) region of JET tokamak discharges with optimized magnetic shear. The suppression occurs in two stages. First, low frequency turbulence and ion transport are reduced across the plasma core by a toroidal velocity shear generated by intense auxiliary heating. Then with the ITB formation, high frequency turbulence and electron transport are reduced locally within the steep pressure gradient region of the ITB.     

High selectivity in new chiral separations of dansyl amino acids by cyclodextrin derivatives in electrokinetic chromatography

Enantiomeric pairs of 11 dansyl derivatives of alpha-amino acids were used as analytes in electrokinetic chromatography to test the ability as chiral selectors of two pure derivatives of beta-cyclodextrin: the ethylendiamine derivative in primary position (CDen) and a member of a new class of receptors, the cysteamine-bridged hemispherodextrin THCMH. The selectivity obtained by the presence of the hemispherodextrin, appears particularly promising as shown by the large values of resolution obtained. The importance of a detailed analysis of these data is discussed in terms of suggestions for a rational approach to separation science.     

Molecular Mechanisms of Photosensitization Induced by Drugs XII. Photochemistry and Photosensitization of Rufloxacin: An Unusual Photodegradation Path for the Antibacterials Containing a Fluoroquinolone-like Chromophore

The UVA irradiation of 9-fluoro-2,3-dihydro-10-4'-methyl-1' -piperazinyl-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzo-thiazine-6-carboxylic acid, rufloxacin, a fluoroquinolone antibacterial that shows photosensitizing properties toward biological substrates, leads to formation of two main steady photoproducts characterized by a decarboxylation process and an opening of the piperazinyl ring, respectively. The deprotonation of the 10-piperazinyl group and the dissociation of the 6-carboxyl group of rufloxacin are strictly pH dependent. The photosensitizing activity was tested toward membranes as biological targets. Red blood cell hemolysis and lipid peroxidation were considered as markers of photosensitization. Ultraviolet A-induced damage is strongly influenced by the presence of oxygen, it is triggered by transient species, such as singlet oxygen and free radicals, photogenerated via rufloxacin irradiation, whereas no drug photoproduct is involved in the photosensitization process.     

Application of charged single isomer derivatives of cyclodextrins in capillary electrophoresis for chiral analysis

The review focuses on the role of ionic or ionisable single isomer derivatives (SIDs) of cyclodextrins on the separation of chiral analytes in capillary electrophoresis (CE), covering the period since the year 2000. The advantages of using pure compounds are discussed, as well as the ways to optimise the separations in the context of a rational approach to these techniques. Specific attention is paid to the modulation of the selector–analyte interaction. The advantage due to a detailed knowledge of equilibria occurring in solution during the CE run is underlined, particularly in the case of the presence of metal complexes, as occurs in chiral ligand exchange capillary electrophoresis (CLECE).     

Resolutions of generic points lying on a smooth quadric

For a 0-dimensional schemeX on a smooth quadricQ we define a special type of resolution of its ideal sheaf as a locally freeO _Q. These resolutions allow to find, for schemes which are generic inQ, the minimal free resolution ofX as a subscheme of ℙ³. For almost all such schemes the graded Betti numbers in ℙ³ depend only on the Hilbert function ofX in ℙ³. Work done with financial support of M.U.R.S.T., while the authors were members of C.N.R.