Gloria Uccello-Barretta
University of Pisa
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Featured researches published by Gloria Uccello-Barretta.
Journal of Pharmaceutical and Biomedical Analysis | 1995
Carlo Bertucci; Giorgio A. Ascoli; Gloria Uccello-Barretta; Lorenzo Di Bari; Piero Salvadori
5-Fluorouracil (FU) is an important and widely used antineoplastic drug that is carried in the serum by plasma proteins. Protein binding studies of this drug to human serum albumin (HSA) have been carried out by several spectroscopic techniques. Difference circular dichroism and UV studies provided information on the class of binding sites involved in the interaction. In particular, displacement experiments showed that FU has at least one secondary binding site in the coumarin binding area, but does not interact with the benzodiazepine binding area. Binding was also investigated by difference 1H NMR and by measuring the increase in the 19F NMR signal of FU when bound to HSA. Finally, evidence was obtained that chemical acetylation of Lys199 results in a decreased apparent binding affinity constant (nK) for FU. Such a modification is induced under physiological conditions by aspirin.
Current Pharmaceutical Design | 2006
Gloria Uccello-Barretta; Federica Balzano; Piero Salvadori
The analysis of enantiorecognition processes involves the detection of enantiomeric species as well as the study of chiral discrimination mechanisms. In both fields Nuclear Magnetic Resonance (NMR) spectroscopy plays a fundamental role, providing several tools, based on the use of suitable chiral auxiliaries, for observing distinct signals of enantiomers and for investigating the complexation phenomena involved in enantiodiscrimination processes.
European Journal of Pharmaceutical Sciences | 2008
Ylenia Zambito; Chiara Zaino; Gloria Uccello-Barretta; Federica Balzano; Giacomo Di Colo
The pH-induced structural modifications of the reaction product between chitosan and 2-diethylaminoethyl chloride are studied with the purpose of testing and comparing the resulting chitosan derivatives on the basis of their intestinal drug permeability-enhancing properties. The reaction reproducibly yielded conjugates comprising short pendant chains of n adjacent diethyl-dimethylene-ammonium groups substituted onto the primary amino group of the chitosan repeating unit. The more significant derivatives, N(+)-Ch-7 (degree of substitution, DS=41%; n=3) and N(+)-Ch-8 (DS=59%; n=1.7) were prepared at pH 7 and 8, respectively. The apparent permeability (P(app)) of excised rat intestine was determined by means of Ussing type chambers. The hydrophilic fluorescein sodium (NaFlu) and fluorescein isothiocyanate dextran (MW 4400 Da) (FD-4), and the lipophilic rhodamine 123 (Rh-123), were applied in Ringer buffer to the apical side. Apical to basolateral transport was measured in the absence or presence of 0.5% (w/v) of the polymer under test. N(+)-Ch-7 and N(+)-Ch-8 were more effective P(app) enhancers than N-trimethyl-chitosan. Both N(+)-Ch-7 and N(+)-Ch-8 enhanced the P(app) of NaFlu (enhancement ratio, ER=1.84 and 1.33, respectively), while N(+)-Ch-8 was the more effective enhancer for FD-4 (ER=2.14). The P(app) of Rh-123 was significantly enhanced only by N(+)-Ch-7 (ER=1.37). Permeant-polymer binding counteracted the enhancement effect of polymer on transmembrane permeant flux. Contact with the chitosan conjugates did not impair the mucosal epithelium integrity.
Tetrahedron | 1993
Dario Pini; Alberto Mastantuono; Gloria Uccello-Barretta; Anna Iuliano; Piero Salvadori
Abstract N,NI-bis-benzyl substituted 1,3-diamine 1a , synthesized in high optical purity, and the corresponding dilithium salt 1b are used, for the first time, as chiral catalysts in the addition of ZnEt2 to aromatic aldehydes. Both 1a and 1b are able to promote the reaction but the products obtained exhibited low enantiomeric excesses. By 1H NMR and UV-CD investigation, experimental evidences about the structure of some reaction intermediates have been gained: reaction pathway consistent with spectroscopic data, chemical and stereochemical results could be postulated.
International Journal of Pharmaceutics | 2010
Gloria Uccello-Barretta; Samuele Nazzi; Ylenia Zambito; Giacomo Di Colo; Federica Balzano; Marco Sansò
An interaction between tamarind seed polysaccharide (TSP) and hyaluronic acid (HA) in aqueous solution has been ascertained. Various TSP/HA mixtures have been studied as the basis for the development of a potential excipient for eye drops synergistically improved over those of the separate polymers. Information about the nature of interpolymer interactions, and their dependence on TSP/HA ratios were obtained by NMR spectroscopy in solution. Superior mucin affinity of TSP/HA mixtures with respect to the single polysaccharides was assessed by NMR proton selective relaxation rate measurements. The mucoadhesivity of the TSP/HA (3/2) mixture, evaluated in vitro by NMR or viscometry, and in vivo by its mean and maximum residence time in rabbit precorneal area, is stronger than that of the component polysaccharides or the TSP/HA mixtures of different composition. TSP/HA (3/2) is little viscous and well tolerated by rabbit eyes. It stabilizes the tear film, thereby prolonging the residence of ketotifen fumarate and diclofenac sodium in tear fluid, but is unable to permeabilize the cornea. In conclusion, mucoadhesivity is responsible for the TSP/HA (3/2) synergistic enhancement of either extra- or intra-ocular drug bioavailability.
Tetrahedron-asymmetry | 1995
Gloria Uccello-Barretta; Dario Pini; Alberto Mastantuono; Piero Salvadori
Abstract The use of quinine as a chiral solvating agent for NMR spectroscopy affords a general method for the enantiomeric purity determination of β-hydroxyesters. The ester group represents the most suitable probe for the measurements, which can be optimized by varying the molar ratio ester/quinine, the total concentration or the temperature.
Journal of Organometallic Chemistry | 1991
Gloria Uccello-Barretta; Raffaello Lazzaroni; Roberta Settambolo; Piero Salvadori
Abstract Differences in the behaviour of the metal-alkyl intermediates involved in the deuterioformylation of styrene in the presence of Co 2 (CO) 8 or Rh 4 (CO) 12 as catalytic precursors, have been readily revealed by 2 H NMR analysis of the crude mixtures present after partial conversion. The results clearly demonstrate the value of this simple method for mechanistic studies of catalytic reactions.
Carbohydrate Research | 1993
Gloria Uccello-Barretta; Claudia Chiavacci; Carlo Bertucci; Piero Salvadori
The inclusion complex of the calcium salt of (S)-2-(3-phenoxyphenyl)propionic acid with cyclomaltoheptaose (beta-cyclodextrin) was investigated by 1H NMR spectroscopy. The stoichiometry of the complex was determined by the continuous variation method and the association constant by the Benesi-Hildebrand procedure. Measurements of proton selective relaxation rates allowed the dynamics of the complex to be investigated and the determination of intermolecular 1H(1H)-NOE enhancements revealed the stereochemistry in solution.
Journal of Chromatography A | 1990
Carlo Bertucci; E. Domenici; Gloria Uccello-Barretta; Piero Salvadori
Abstract A bonded β-cyclodextrin chiral stationary phase was used for the chromatographic resolution of a series of 1,4-benzodiazepin-2-ones (BDZs). This column can also be employed for the direct resolution of ionic BDZs as the hemisuccinate esters of 3-hydroxy-BDZs. Nuclear magnetic resonance spectroscopy was used to obtain preliminary information on the mechanism of chiral discrimination.
Journal of Chromatography A | 2010
Gloria Uccello-Barretta; Letizia Vanni; Federica Balzano
NMR spectroscopy represents a valuable tool for obtaining information about structure and dynamics at a molecular level on the diastereoisomeric complexes formed by enantiomeric substrates and chromatographic chiral selectors or modifiers. Some examples collected from the literature show the potentialities of solution NMR spectroscopy in the rationalization of chromatographic enantiorecognition processes and the different NMR approaches needed according to the chiral selector features.