Physico-chemical properties of aqueous drug solutions: From the basic thermodynamics to the advanced experimental and simulation results.

The physical chemical properties of aqueous solutions of model compounds are illustrated in relation to hydration and solubility issues by using three perspectives: thermodynamic, spectroscopic and molecular dynamics simulations. The thermodynamic survey of the fundamental backgrounds of concentration dependence and experimental solubility results show some peculiar behavior of aqueous solutions with several types of similar solutes. Secondly, the use of a variety of experimental spectroscopic devices, operating under different experimental conditions of dimension and frequency, has produced a large amount of structural and dynamic data on aqueous solutions showing the richness of the information produced, depending on where and how the experiment is carried out.

Use of Capillary Electrophoresis for Polysaccharide Studies and Applications.

CE applications to charged polysaccharides are briefly reported. A simple procedure is presented to determine the esterification degree of a hyaluronan derivative. In this case the degree of substitution was as low as 14 %.

"The Good, the Bad and the Ugly" of Chitosans.

The objective of this paper is to emphasize the fact that while consistent interest has been paid to the industrial use of chitosan, minor attention has been devoted to spread the knowledge of a good characterization of its physico-chemical properties. Therefore, the paper attempts to critically comment on the conflicting experimental results, highlighting the facts, the myths and the controversies. The goal is to indicate how to take advantage of chitosan versatility, to learn how to manage its variability and show how to properly tackle some unexpected undesirable features.

Exosomal doxorubicin reduces the cardiac toxicity of doxorubicin.

Aim: To test the efficacy and toxicity of exosomal doxorubicin (exoDOX) compared with free doxorubicin.

Materials & Methods: The cytotoxic effects of exoDOX were tested in vitro and in nude mice by measuring the tumor volume. The toxic effects were evaluated by measuring the bodyweight and through histopathologic analyses.

Myelography iodinated contrast media. I. Unraveling the atropisomerism properties in solution.

The present work reports a thorough conformational analysis of iodinated contrast media: iomeprol, iopamidol (the world's most utilized contrast agent), and iopromide. Its main aim is the understanding of the complex structural features of these atropisomeric molecules, characterized by the presence of many conformers with hindered rotations, and of the role of atropisomerism in the physicochemical properties of their aqueous solutions. The problem was tackled by using an extensive analysis of (13)C NMR data on the solutions of whole molecules and of simple precursors in addition to FT-IR investigation and molecular simulations.

Analysis of N-acetylaminosugars by CE: a comparative derivatization study.

N-linked or O-linked glycans derived from glycoprotein processing carry, an N-acetylglucosamine or an N-acetylgalactosamine respectively, at their reducing termini. The presence of the N-acetylamino group on C-2 of reducing sugar residues has been reported to hamper the derivatization reaction with a chromophore at the anomeric centre. In this paper N-acetyllactosamine, N-acetylglucosamine, N-acetylgalactosamine and several other neutral monosaccharides are coupled to three different dyes (4-aminobenzonitrile, 2-aminopyridine, 2-aminobenzoic acid (2-AA)) by reductive amination and analysed by CE with UV detection.

Use of capillary electrophoresis for polysaccharide studies and applications.

Capillary electrophoresis (CE) applications to charged polysaccharides are briefly reported. A simple procedure is presented to determine the esterification degree of a hyaluronan derivative. In this case, the degree of substitution was as low as 14%.

Separation of O- and C-allyl glycoside anomeric mixtures by capillary electrophoresis and high-performance liquid chromatography.

Rapid and reliable methods for the analysis of O- and C-allyl galactopyranosides and glucopyranosides are presented, based on capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC). In MEKC, the formation of chromophoric and charged complexes between the saccharides and borate as well as the hydrophobic interactions with micelles jointly contributed to the selective separation and sensitive detection of all the investigated anomeric couples. Some non-purified synthesis mixtures of C-allyl glycosides were successfully characterised without pre-treatment.

The role of Galectin-1 in the interaction between chondrocytes and a lactose-modified chitosan.

Evidences for the involvement of the Galectin-1 in the interaction of pig chondrocytes with a lactose-modified chitosan, namely Chitlac, are reported. The Chitlac glycopolymer has been shown to promote pig chondrocyte aggregation and to induce extracellular matrix production. Highly pure Galectin-1 was obtained from pig spleen by affinity chromatography and its identity was determined by ion spray mass spectrometry analysis of tryptic peptide fragments obtained after in-gel digestion.

Galactose-substituted alginate 2: conformational aspects.

Galactose moieties have been introduced on the uronic groups of alginates from different sources via an N-glycosidic bond, thus affecting the net charge on the polymer chain. The modified polymers have been analyzed by means of viscosity and of high-performance size-exclusion chromatography combined with refractive index multiple angle laser light scattering (HPSEC-RI-MALLS) measurements. The latter technique enabled us to determine the molecular weight of the modified polymers, proving that the synthetic procedure did not affect the chemical integrity of the chain.

Galactose-substituted alginate: preliminary characterization and study of gelling properties.

Coupling of alginate with 1-amino-1-deoxygalactose in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide results in a substituted polymer containing galactose side linked via an amide bond. To clarify the degree and pattern of substitution, a (1)H NMR study on the anomeric region of modified alginate, polymannuronate, alginate enriched in guluronic acid (G-enriched alginate), and polyalternating MG, was carried out (G, alpha-l-guluronic acid; M, beta-d-mannuronic acid). From the resonance of the proton at position 1 of galactosylamine, it was possible to determine the amount of galactose linked to mannuronic and to guluronic residues, respectively.

Determination of the diadic composition of alginate by means of circular dichroism: a fast and accurate improved method.

Circular dichroism (CD) is presented as a reliable and sensitive method of determining the diadic frequency composition of alginate (F(GG), F(MM) and F(GM+MG)). The availability of samples, very largely or even completely conforming to the limiting structures of polymannuronate (MM)(n), polyguluronate (GG)(n) and polyalternating MG (MG)(n), respectively, allowed the limiting CD spectra for each alginate diad to be obtained. These showed very different CD behaviour, thus pointing out the crucial importance of the neighbouring residue in chiroptical properties.

Enzymatic synthesis and characterization of oligosaccharides structurally related to the repeating unit of Pullulan.

A trisaccharide (Glcalpha1-4Glcalpha1-6Glc) and a tetrasaccharide (Glcalpha1-4Glcalpha1-4Glcalpha1-6Glc) the structures of which are related to that of repeating unit of pullulan have been obtained, exploiting the transglycolytic activity of Aspergillus niger cyclodextrin glucanotransferase. Both products were obtained in one-pot reaction using as a donor the alpha-cyclodextrin and as an acceptor the disaccharide isomaltose. The regioselectivity of the reaction was 85% for the tetrasaccharide and 80% for the trisaccharide.

Synthesis, characterization, and preliminary biological study of glycoconjugates of poly(styrene-co-maleic acid).

Three derivatives of the biocompatible polymer poly(styrene-co-maleic anhydride) (SMA) were obtained with 1-amino-1-deoxy-beta-D-galactose, 1-amino-1-deoxy-beta-D-glucose, and 1-amino-1-deoxy-beta-D-lactose, respectively. The amino sugars were chemically conjugated via formation of an amide bond between the anomeric amino group of the sugar residue and the anhydride of the copolymer, giving the corresponding glycoconjugate derivatives. Colorimetric assay of the unreacted amino groups and elemental analysis were used to determine the degree of substitution.

Synthesis and characterization of a novel glycopolymer with protective activity toward human anti-alpha-Gal antibodies.

An efficient and rapid synthesis of the derivative of the biocompatible polymer poly(styrene co-maleic acid) with Linear B disaccharide (Galili antigen) was achieved. The oligosaccharide portion was obtained by a transglycosylation reaction catalyzed by coffee bean alpha-D-galactosidase using p-nitrophenyl-alpha-D-galactopyranoside both as donor and as acceptor. The reaction was carried out in aqueous buffer without any organic cosolvent.

Structural investigations of cross-linked hyaluronan.

Structural properties of several cross-linked hyaluronan derivatives, obtained by scanning electron microscopy, monodimensional NMR microscopy and small angle X-ray scattering of synchrotron radiation, are presented and compared with those observed for non-modified hyaluronic acid, used as a reference material. The experimental results, obtained in different media, showed a consistent picture of the synthesized matrices. In particular, the presence of zones of denser polymeric material observed by electron microscopy resulted in a higher transversal relaxation rate of the bulk water protons as well as in a decrease of the diffusion coefficient obtained by NMR microscopy.