Comprehensive normal-phase x reversed-phase liquid chromatography coupled to photodiode array and mass spectrometry detection for the analysis of free carotenoids and carotenoid esters from mandarin

In the present work, a novel strategy including the use of two different comprehensive HPLC methods has been employed to study the whole carotenoid composition of mandarin essential oil. Thus, two different fully orthogonal two-dimensional HPLC methods have been used. A silica microbore column was coupled to a C(18) monolithic column to study the mandarin saponified extract, while the coupling of a cyano microbore column to a C(18) monolithic column was employed to study the intact mandarin essential oil sample in order to characterize the native carotenoid esters composition. Detection was performed by connecting a photodiode array detection (DAD) system in parallel with a MS detection system operated with an atmospheric pressure chemical ionization (APCI) interface. Thus, the carotenoid identification was carried out by combining the information provided by the DAD and MS systems and the peaks relative position in the two-dimensional chromatograms.     

Diaminotrehalose-capped β-cyclodextrin, a new member of hemispherodextrins: synthesis, thermodynamic and spectroscopic characterization and its exploitation in chiral electrokinetic chromatography

The diaminotrehalose-capped derivative of β-CD, a new member of hemispherodextrins, was synthesized and characterized by NMR spectroscopy. Its protonation constants were determined by potentiometry, and the inclusion of both the enantiomers of dansyl-phenylalanine was investigated by NMR spectroscopy. Its stereoselective properties were exploited in electrokinetic chromatography by separating four enantiomeric pairs of dansyl derivatives of amino acids.     

The 3-amino-derivative of γ-cyclodextrin as chiral selector of Dns-amino acids in electrokinetic chromatography

The enantioseparation of the enantiomeric pairs of 10 Dns derivatives of α-amino acids was successfully carried out by using for the first time the 3-amino derivative of the γ-cyclodextrin. The effects of pH and selector concentration on the migration times and the resolutions of analytes were studied in detail. 3-Deoxy-3-amino-2(S),3(R)-γ-cyclodextrin (GCD3AM) shows very good chiral recognition ability even at very low concentrations at all the three investigated values of pH, as shown by the very large values of selectivity and resolution towards several pairs of amino acids. The role played by the cavity, the substitution site and the protonation equilibria on the observed properties of chiral selectivity, on varying the specific amino acid involved, is discussed.     

Chemical characterization of unconventional palm oils from Hyophorbe indica and two other endemic Arecaceae species from Reunion Island

Abstract

Chemical characteristics of novel seed oils, yet not investigated, from three endemic Arecaceae (palm) species from Reunion Island are described. Fatty acid profiles are performed using two-dimensional gas chromatography-mass spectrometry. Carotenoid contents are determined by high performance liquid chromatography-mass spectrometry. The results of the investigations emphasize the particular composition of the unconventional red seed oil from Hyophorbe indica. Characteristic features of this oil reveal a high degree of unsaturation (50% of polyunsaturated fatty acids, with a high content (17%) of omega-3), which is possibly a unique fatty acid composition in the Arecaceae family. The two other palm oils from Dictyosperma album and Latania lontaroides contain high level of saturated fatty acids very similar to that of the edible palm oil. H. indica oil is also very rich in valuable carotenoids; in particular, lutein, β-carotene and lycopene are detected in a high content (respectively 45, 23 and 35?mg.kg^?1 in oil).     

Calorimetric Evaluation of Glycyrrhetic Acid (GA)- and Stearyl Glycyrrhetinate (SG)-Loaded Solid Lipid Nanoparticle Interactions with a Model Biomembrane

Glycyrrhetic acid (GA) and stearyl glycyrrhetinate (SG) are two interesting compounds from Glycyrrhiza glabra, showing numerous biological properties widely applied in the pharmaceutical and cosmetic fields. Despite these appreciable benefits, their potential therapeutic properties are strongly compromised due to unfavourable physical-chemical features. The strategy exploited in the present work was to develop solid lipid nanoparticles (SLNs) as carrier systems for GA and SG delivery. Both formulations loaded with GA and SG (GA-SLNs and SG-SLNs, respectively) were prepared by the high shear homogenization coupled to ultrasound (HSH-US) method, and we obtained good technological parameters. DSC was used to evaluate their thermotropic behaviour and ability to act as carriers for GA and SG. The study was conducted by means of a biomembrane model (multilamellar vesicles; MLVs) that simulated the interaction of the carriers with the cellular membrane. Unloaded and loaded SLNs were incubated with the biomembranes, and their interactions were evaluated over time through variations in their calorimetric curves. The results of these studies indicated that GA and SG interact differently with MLVs and SLNs; the interactions of SG-SLNs and GA-SLNs with the biomembrane model showed different variations of the MLVs calorimetric curve and suggest the potential use of SLNs as delivery systems for GA.     

Donkey Milk Fermentation by Lactococcus lactis subsp. cremoris and Lactobacillus rhamnosus Affects the Antiviral and Antibacterial Milk Properties

Background: Milk is considered an important source of bioactive peptides, which can be produced by endogenous or starter bacteria, such as lactic acid bacteria, that are considered effective and safe producers of food-grade bioactive peptides. Among the various types of milk, donkey milk has been gaining more and more attention for its nutraceutical properties. Methods: Lactobacillus rhamnosus 17D10 and Lactococcus lactis subsp. cremoris 40FEL3 were selected for their ability to produce peptides from donkey milk. The endogenous peptides and those obtained after bacterial fermentation were assayed for their antioxidant, antibacterial, and antiviral activities. The peptide mixtures were characterized by means of LC-MS/MS and then analyzed in silico using the Milk Bioactive Peptide DataBase. Results: The peptides produced by the two selected bacteria enhanced the antioxidant activity and reduced E. coli growth. Only the peptides produced by L. rhamnosus 17D10 were able to reduce S. aureus growth. All the peptide mixtures were able to inhibit the replication of HSV-1 by more than 50%. Seventeen peptides were found to have 60% sequence similarity with already known bioactive peptides. Conclusions: A lactic acid bacterium fermentation process is able to enhance the value of donkey milk through bioactivities that are important for human health.     

Characterization of poly[(R)-3-hydroxybutyrate-co-epsilon-caprolactone] copolymers by matrix-assisted laser desorption/ionization time-of-flight and electrospray ionization mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) of narrowly dispersed molecular weight gel permeation chromatography (GPC) fractions was used to characterize random and microblock poly[(R)-3-hydroxybutyrate-co-epsilon-caprolactone] [P(HB-co-CL)] copolymers obtained via the acid-catalyzed transesterification of the corresponding homopolymers, poly([(R)-3-hydroxybutyrate] (PHB) and poly(epsilon-caprolactone) (PCL). High-quality mass spectra were obtained, which made it possible to establish the nature of the polymer end groups. Besides the carboxylic termination, two other moieties were found: alcoholic and tosyl end groups. MALDI mass spectra of CL-rich samples possessed mostly tosyl end groups, while HB-rich samples possessed mostly alcoholic end groups, showing that the tosyl moiety is linked prevalently to CL terminal units. The higher resolution of electrospray ionization (ESI) mass spectra of lower molecular weight GPC fractions permitted the identification of the different oligomer species hypothesized in the assignment of the corresponding MALDI mass spectra. Partial methanolysis of these copolymers was explored as a method of producing mixed HB-CL oligomers to be utilized as new synthons, possessing a minor number of chiral centers from those obtained from hydrolysis of biotechnologically synthesized poly(hydroxyalkanoates) (PHAs).     

Facile light-triggered one-step synthesis of small and stable platinum nanoparticles in an aqueous medium from a beta-cyclodextrin host-guest inclusion complex

It is shown, for the first time, that small (ca. 2 nm) and stable platinum nanoparticles can be easily obtained in one step through visible light irradiation of a host-guest inclusion complex between beta-cyclodextrin and platinum acetylacetonate in a water solution. The exclusive control of the reaction by an external trigger, the removal of the undesired reaction products without any manipulation of the sample, and the absence of ionic repulsions between the metal nanoparticles represent the main remarkable advantages offered by this synthetic methodology.     

On the rao module of a curve lying on a smooth cubic surface in p3, II

We find that every reduced and irreducible curve C on a smooth cubic surface is k-Buchsbaum, with k equal to the diameter of the Rao module M(C). Moreover we determine the diameters of the submodules generated by all the elements with the same degree in a minimal set of generators of M(C).