Giuseppe Lubinu

Polymeric nanoparticles encapsulating white tea extract for nutraceutical application.

With the aim to obtain controlled release and to preserve the antioxidant activity of the polyphenols, nanoencapsulation of white tea extract into polymeric nanoparticles (NPs) based on poly(ε-caprolactone) (PCL) and alginate was successfully performed. NPs were prepared by nanoprecipitation method and were characterized in terms of morphology and chemical properties. Total polyphenols and catechins contents before and after encapsulation were determined. Moreover, in vitro release profiles of encapsulated polyphenols from NPs were investigated in simulated gastrointestinal fluids. The antioxidant activity and stability of encapsulated extract were further evaluated. Interestingly, NPs released 20% of the polyphenols in simulated gastric medium, and 80% after 5 h at pH 7.4, showing a good capacity to control the polyphenols delivery. Furthermore, DPPH(•) assay confirmed that white tea extract retained its antioxidant activity and NPs protected tea polyphenols from degradation, thus opening new perspectives for the exploitation of white tea extract-loaded NPs for nutraceutical applications.

A POTENTIOMETRIC, SPECTROPHOTOMETRIC AND 1H NMR STUDY ON THE INTERACTION OF CIMETIDINE, FAMOTIDINE AND RANITIDINE WITH PLATINUM(II) AND PALLADIUM(II) METAL IONS

Abstract Spectrophotometric, potentiometric and 1H NMR results on the M-L systems [M = PdII or PtII and L = cimetidine, famotidine or ranitidine] are clearly indicative of the strong chelating ability of these antiulcerative drugs towares metal ions. In view of the great biological interest in these two metals, their coordination to such drugs should have significant implications.

Effect of chitosan concentration on PLGA microcapsules for controlled release and stability of resveratrol.

The polyphenols as nutraceutical and therapeutic agents are gaining growing interest for their beneficial effects and potential in human health. In order to protect their scaffolds and functionality, and to improve the bioavailability, the microencapsulation can represent a promising strategy. This study reports on the formulation of the natural resveratrol (RSV) into microcapsules (MCs) prepared by using different concentrations of chitosan (CS) and poly(D,L-lactic-co-glycolic acid) (PLGA) as polymeric matrix. MCs were prepared by W/O/W double emulsion method and characterized in terms of morphology, size, encapsulation efficiency, physicochemical and thermal properties. RSV release behavior from MCs was evaluated under simulated gastrointestinal fluids, and the long term stability was monitored at different storage conditions. MCs resulted to have spherical shape and different morphology, with size ranging from 11 to 20 μm, and encapsulation efficiencies of 40-52%, depending on the CS concentration. Moreover, MCs containing CS exhibited a significant lower release of RSV than those containing only PLGA. Furthermore, all tested formulations were able to ensure a good retention and stability of encapsulated RSV until 6 months. In summary, CS/PLGA MCs can be proposed as an attractive delivery system to control the release and long term protection of RSV.

An 1H NMR and potentiometric study of the interaction between platinum(II) and cimetidine

Abstract The platinum(II)-cimetidine system was studied in aqueous solutions by potentiometric and 1H NMR methods. Evidence is given of the formation of 1:1 and 1:2 platinum(II)-ligand complexes, with different degrees of protonation. A bonding scheme is proposed on the basis of NMR spectra.

Photodegradation of Organic Waste Coupling Hydrogenase and Titanium Dioxide

In this work the results of the study on the degradation of dairy waste and lactose with use of titanium dioxide (TiO2), as photocatalyst, are presented. The ability of TiO2 to degrade dairy waste is compared either in the presence of molecular oxygen or of a bacterial hydrogenase as electron acceptor. The enzyme-mediated H2 production rates or the O2 consumption rates are used to measure electron donor degradation. The results obtained clearly indicate that dairy waste can be degraded by the TiO2 photocatalyst. Proteins present in the dairy waste have a strong inhibitory effect on the degradation process. Indeed lactose alone can easily be degraded. When the protein extract obtained from the dairy waste was added to the lactose solution, the reaction for both electron acceptors, hydrogenase and oxygen, was inhibited. When the dairy waste solutions were diluted, there was a positive effect on the reaction rate. This was particularly true in the case of hydrogenase, and to a lesser extent in the case of oxygen acceptor. The reduction of the pH from 8 to 6 also increased H2 production when the enzyme was used.

Potentiometric and 13C NMR study of the interaction between boric acid and pyrogallol (1,2,3-trihydroxybenzene)

Abstract The boric acid-pyrogallol system has been studied in aqueous solution by means of potentiometric methods. Evidence is given for two adducts of 1 : 1 and 1 : 2 stoichiometry. An analysis of 13C NMR spectra of the 1 : 2 adduct is presented.

Synthesis, NMR study, and X-ray structure of 2-(N-methyl-N′-cyano-N″-ethylguanidino) thiotriophenylphosphinegold(I)

The reaction between cimetidine in a methanolic solution of KOH and a dichloromethane solution of PPh3AuCl affords a new compound with formula [L-Au-PPh3] (I) (L = 2-(N-methyl-N′-cyano-N″-ethylguanidino)thiolate), the thiolato ligand resulting from cleavage of one of the thioether bonds of cimetidine. (I) has been characterized by elemental analysis, infrared, and 1H and 13C NMR spectroscopy. Single crystal x-ray structure determination shows that the gold atom is linearly coordinated by a phosphine ligand (Au-P 2.258(1) A) and by an S atom (Au-S 2.282(1) A) of the thiolato ligand. Crystal data: triclinic, space group P1 with a = 8.848(1), b = 11.343(3), c = 12.107(3)A, α = 87.63(1), β = 85.24(1), γ = 79.89(1)°, R = 0.024 for 3673 reflections with I > 3 δ (I).