Stefania Petralito

Solubility, spectroscopic properties and photostability of Rhein/cyclodextrin inclusion complex

The host-guest interaction between Rhein (Rh)--an anthraquinonic drug characterized by low water solubility and recently considered for its potential antidiabetic and antitumoral activities other than for the well-established anti-inflammatory properties--with cyclodextrins (CDs) was investigated using phase-solubility diagrams. The typical A(L) phase-solubility profiles suggest the formation of the 1:1 inclusion complexes between Rh and the two CDs investigated, namely beta-cyclodextrin and 2-hydroxypropyl-beta-cyclodextrin and the resulting constant values of complex formation, K(c), were estimated. Due to the higher K(c) value, complex of Rhein with 2-hydroxypropyl-beta-cyclodextrin was chosen for further investigation. Characterization in solution of 2-hydroxypropyl-beta-cyclodextrin/Rhein complex was achieved both by fluorescence and visible spectroscopic techniques. These results confirm the formation of inclusion complexes in solution and the 1:1 stoichiometry of the binary system. With respect to Rhein aqueous solution behavior, the inclusion complex appears to be able: (i) to enhance Rhein solubility; (ii) to control its neutral/anionic equilibrium; (iii) to affect both its electronic absorption and fluorescence spectra. Finally, the photostability of Rhein in the presence of cyclodextrins was evaluated.

Surfactant-induced leakage from liposomes: a comparison among different lecithin vesicles

The interactions, at sublytic concentration, of Triton X-100 and sodium cholate with sonicated and extruded liposomes of egg and soya lecithins were considered to analyze the integrity and/or the barrier efficiency of liposomal membranes. Results are discussed in terms of surfactant partition between the aqueous and the lipid phases and of the release of a fluorescent hydrophilic probe. Phospholipid nature and liposome size influence detergent partition, whereas the content release is mainly affected by the surfactant mole fraction in the bilayer, and by the liposome size.

Controllable release from high-transition temperature magnetoliposomes by low-level magnetic stimulation

High-transition temperature liposomes with embedded coated magnetite nanoparticles were prepared using the thin lipid film hydration method in order to obtain magnetoliposomes not sensitive to temperature increase (at least up to 50°C). Accordingly, drug can be released from such magnetoliposomes using a low-level electromagnetic field as triggering agent, while no delivery would be obtained with temperature increase within the physiological acceptable range. The hypothesized release mechanism involves mechanical stress of the liposome membrane due to nanoparticles oscillations and it is investigated by means of a numerical model evaluated using multiphysics simulations. The carrier content was repetitively released by switching on and off a 20kHz, 60A/m magnetic field. The results indicated high reproducibility of cycle-to-cycle release induced by the magnetic-impelled motions driving to the destabilization of the bilayer rather than the liposome phase transition or the destruction of the liposome structure.

Kinetics of surfactant-induced release from liposomes: a time-dependent permeability model

Abstract The article examines membrane permeabilization and the consequent content release of lipid vesicles due to the addition of surfactant. Experimental results show that content release involves a complex kinetics where almost instantaneous release is followed by prolonged slow leakage. The model proposed therefore regards bilayer permeability as varying with the time elapsed from the moment of surfactant addition. A delta function followed by an exponentially decaying profile is assumed for these permeability curves. The effects of surfactant concentration and type (Triton X-100, Tween 20 and Tween 60) can be compared by comparing the fitting parameters of the permeability curves.

Controlled release from magnetoliposomes aqueous suspensions exposed to a low intensity magnetic field

Recently, the use of liposomes loaded with magnetic nanoparticles (magnetoliposomes, (MLs)) has been intensely growing as a new drug delivery system. With the use of alternating magnetic fields, it is possible to remotely control the delivery of a drug or any other macromolecule loaded inside the MLs. In this experiment, the release of a fluorescent dye from MLs is achieved through an alternating magnetic field of 20 kHz and amplitude below 100 A/m, and without a macroscopic temperature increase.

Apparent Solubility and Dissolution Profile at Non-Sink Conditions as Quality Improvement Tools

Stefania Petralito1,*, Iacopo Zanardi2,*, Adriana Memoli1, M. Cristina Annesini3, Vincenzo Millucci4 and Valter Travagli2 1Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Universita di Roma, 2Dipartimento Farmaco Chimico Tecnologico, Universita degli Studi di Siena, 3Dipartimento di Ingegneria Chimica Materiali Ambiente, Sapienza Universita di Roma, 4Dipartimento di Fisica, Universita degli Studi di Siena, Italy

Cyclodextrin/Diacerein inclusion complex: A tool for therapeutic drug delivery

Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Universita di Roma, Piazzale A. Moro 5, 00185 Roma, Italy Dipartimento Farmaco Chimico Tecnologico, Universita degli Studi di Siena, Viale Aldo Moro 2, 53100 Siena, Italy 3 Dipartimento di Ingegneria Chimica, dei Materiali, delle Materie Prime e Metallurgia, Sapienza Universita di Roma, Via Eudossiana 18, 00184 Roma, Italy stefania.petralito@uniroma1.it

DESIGN AND CHARACTERIZATION OF A BIOCOMPATIBLE PHYSICAL HYDROGEL BASED ON SCLEROGLUCAN FOR TOPICAL DRUG DELIVERY

Physical hydrogels of a high-carboxymethylated derivative of scleroglucan (Scl-CM300) were investigated as potential systems for topical drug delivery using three different therapeutic molecules (fluconazole, diclofenac and betamethasone). Rheological tests were carried out on drug-loaded hydrogels along with in-vitro release studies in a vertical Franz cell, in order to investigate if and how different drugs may influence the rheological and release properties of Scl-CM300 hydrogels. Experimental results and theoretical modeling highlighted that, in the absence of drug/polymer interactions (as for fluconazole and betamethasone) Scl-CM300 matrices offer negligible resistance to drug diffusion and a Fickian transport model can be adopted to estimate the effective diffusion coefficient in the swollen hydrogel. The presence of weak drug/hydrogel chemical bonds (as for diclofenac), confirmed by frequency sweep tests, slow down the drug release kinetics and a non-Fickian two-phase transport model has to be adopted. In-vivo experiments on rabbits evidenced optimal skin tolerability of Scl-CM300 hydrogels after topical application.

Lycium barbarum polysaccharides: Extraction, purification, structural characterisation and evidence about hypoglycaemic and hypolipidaemic effects. A review

In the last decades, glycoconjugates from Lycium barbarum L. fruit (Goji berry) have received a great attention for their potential health-promoting effects. The present review includes a survey of extraction and purification methods of these bioactive molecules (L. barbarum polysaccharides, LBPs), along with a dissertation on the structural characterisation of the carbohydrate component. Furthermore, an overview of in vitro, in vivo and clinical studies concerning the hypoglycaemic and hypolipidaemic effects of isolated LBP fractions, is reported. The evidence suggests that these purified components of the Goji berry may be potentially useful as adjuvants in the treatment of diabetes and its correlated illnesses.

Carotenoid content of Goji berries: CIELAB, HPLC-DAD analyses and quantitative correlation

Fruits of Lycium barbarum L. have been used in Chinese traditional medicine for centuries. In the last decade, there has been much interest in the potential health benefits of many biologically constituents of these fruits. The high level of carotenoids offers protection against development of cardiovascular diseases, diabetes and related comorbidities. In the present work two different selections of Lycium barbarum L., cultivated in Italy and coming from three discrete harvest stages, were subjected to two different grinding procedure and to a simplified extraction method of carotenoid component. CIELAB colorimetric analysis of the freshly prepared purees and HPLC-DAD analysis of carotenoid extracts were performed and compared. Different harvesting dates and grinding procedures deeply influence the carotenoids content and statistical analysis showed high correlation between carotenoid content and colorimetric data. The final model provides a reliable tool to directly assess carotenoid content by performing cheap and routinely colorimetric analyses for food industry.