Influence of the "host-guest" interactions on the mobility of genistein/beta-cyclodextrin inclusion complex

Rutin-Loaded Solid Lipid Nanoparticles: Characterization and In Vitro Evaluation

This study was aimed at preparing and characterizing solid lipid nanoparticles loading rutin (RT-SLNs) for the treatment of oxidative stress-induced diseases. Phospholipon 80H® as a solid lipid and Polysorbate 80 as surfactant were used for the SLNs preparation, using the solvent emulsification/diffusion method. We obtained spherical RT-SLNs with low sizes, ranging from 40 to 60 nm (hydrodynamic radius) for the SLNs prepared starting from 2% and 5% (w/w) theoretical amount. All prepared formulations showed negative zeta-potential values. RT was efficiently encapsulated within SLNs, obtaining high encapsulation efficiency and drug content percentages, particularly for SLNs prepared with a 5% theoretical amount of RT. In vitro release profiles and analysis of the obtained data applying different kinetic models revealed Fickian diffusion as the main mechanism of RT release from the SLNs. The morphology of RT-SLNs was characterized by scanning electron microscopy (SEM), whereas the interactions between RT and the lipid matrix were investigated by Raman spectroscopy, evidencing spectral modifications of characteristic bands of RT due to the establishment of new interactions. Finally, antioxidant activity assay on human glioblastoma astrocytoma (U373) culture cells showed a dose-dependent activity for RT-SLNs, particularly at the highest assayed dose (50 μM), whereas the free drug showed the lesser activity.

Thermal fluctuations in chemically cross-linked polymers of cyclodextrins

The extent and nature of thermal fluctuations in the innovative class of cross-linked polymers called cyclodextrin nanosponges (CDNS) are investigated, on the picosecond time scale, through elastic and quasielastic neutron scattering experiments. Nanosponges are complex 3D polymer networks where covalent bonds connecting different cyclodextrin (CD) units and intra- and inter-molecular hydrogen-bond interactions cooperate to define the molecular architecture and fast dynamics of the polymer. The study presented here aims to clarify the nature of the conformational rearrangements activated by increasing temperature in the nanosponge polymer, and the constraints imposed by intra- and inter-molecular hydrogen-bond patterns on the internal dynamics of the macromolecule. The results suggest a picture, in which conformational rearrangements involving the torsion of the OH groups around the C-O bonds dominate the internal dynamics of the polymer over the picosecond time scale. Moreover, the estimated values of mean square displacements reveal that the motions of the hydrogen atoms in the nanosponges are progressively hampered as the cross-linking degree of the polymer is increased. Finally, the study of the molecular relaxations suggests a dynamical rearrangement of the hydrogen-bond networks, which is characterized by a jump diffusion motion of the more mobile hydrogen atoms belonging to the OH groups of the CD units. All these findings add further contribution to the rational comprehensive view of the dynamics of these macromolecules, which may be particularly beneficial in designing new drug-delivery systems with tuneable inclusion/release properties.

Changes in the anti-inflammatory activity of soy isoflavonoid genistein versus genistein incorporated in two types of cyclodextrin derivatives

BACKGROUND

The isoflavonoid genistein represents the major active compound from soybean, the vegetal product from Glycine max (Fabaceae). The aim of this study is to prove that genistein was incorporated in two semisynthetic cyclodextrins, beta-cyclodextrin derivatives: hydroxypropyl-beta-cyclodextrin and randomly-methylated-beta-cyclodextrin as well as to compare the anti-inflammatory activity of genistein with that of genistein incorporated in these two types of semisynthetic cyclodextrins.

RESULTS

The animal studies were conducted on 8-week old C57BL/6 J female mice. Inflammation was induced in both ears of each mouse by topical application of 10 micrograms 12-O-tetradecanoylphorbol-3-acetate dissolved in 0.1 ml solvent (acetone : dimethylsulfoxide in a molar ratio 9:1). Thirty minutes later treatment was applied. The inflammatory reaction was correlated with increased values in ear thickness. Treatment with genistein and genistein incorporated in the two cyclodextrins led to decreased values for ear thickness. Better anti-inflammatory action was found for the complexes of genistein. Both haematoxylin-eosin analysis and CD45 marker expression are in agreement with these findings.

CONCLUSIONS

Results allow concluding that genistein is an active anti-inflammatory phytocompound and its complexation with hydrophilic beta-cyclodextrin derivatives leads to a stronger anti-inflammatory activity.