D Raneri

Improvement in solubility and dissolution rate of flavonoids by complexation with β-cyclodextrin

The inclusion into the beta-cyclodextrin is used to improve pharmacokinetic characteristics of hesperetin and naringenin. Solubility of hesperetin and naringenin with increasing concentrations of beta-cyclodextrin grows as long as the temperature increased. Stability constants were determined by the solubility method by Higuchi and Connors at different temperatures, and the thermodynamic parameters were calculated for inclusion complex formation in aqueous solution. The solid complexes were obtained in a molar ratio of 1:1 and their dissolution behavior at different pH was examined.

Study of flavonoids/β-cyclodextrins inclusion complexes by NMR, FT-IR, DSC, X-ray investigation☆

Flavonoids are natural substances with a lot of biological activities, including the antioxidant one. Their use in pharmaceutical field is, however, limited by their aqueous insolubility. As the formation of the inclusion complexes can improve their solubility in water, the flavonoids hesperetin, hesperidin, naringenin and naringin have been complexed with beta-cyclodextrin (beta-CD) by the coprecipitation method and studied in solution and in solid state by NMR, FT-IR, differential scanning calorimetry and X-ray techniques. The effects of complexation on the chemical shifts of the internal and external protons of beta-CD in the presence of each flavonoid were observed.

Comparative photodegradation studies on 3-hydroxyflavone: influence of different media, pH and light sources

3-Hydroxyflavone (3-OH-F) photochemistry in solution has been rationalized in terms of an excited state intramolecular proton transfer (ESIPT), which involves the free 3-hydroxy group interacting with the ortho-carbonyl. This photo-rearrangement occurs rapidly and is strongly influenced by the physico-chemical properties of the solvent, which plays an essential role in determining whether a photo-oxidation or a photo-induced molecular rearrangement takes place. 3-OH-F photoreactivity has been deeply investigated and the related mechanisms elucidated, as affected by various solvents, pH values and irradiation wavelengths, leading to different photodegradation rates and pathways. Moreover, the influence of molecular encapsulation upon alpha- and beta-cyclodextrins (alpha- and beta-CyD) on the molecule photoreactivity has been examined, as a potential tool for increasing molecule photostability as well as minimizing photoinduced toxic effects on biosubstrates.

Study of β-blockers/β-cyclodextrins inclusion complex by NMR, DSC, X-ray and SEM investigation ☆

Abstract The formation of inclusion complexes between β-cyclodextrin with the two β-blockers, atenolol and celiprolol, have been studied in the aqueous environment and in the solid state by nuclear magnetic resonance (NMR) spectroscopy, X-ray, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) techniques. The magnitude of the chemical shifts of the interior and exterior β-cyclodextrin protons in the presence of each β-blocker indicated that these are included within the β-cyclodextrin cavity. In aqueous solution they form 1:1 complexes. In the solid state the formation of the β-cyclodextrin/atenolol (celiprolol) complexes is confirmed by X-ray, DSC and SEM, also employed to characterize pure substances and their physical mixtures.

Synthesis, Chiral Resolution and Pharmacological Evaluation of a 2,3-Benzodiazepine-Derived Noncompetitive AMPA Receptor Antagonist

2,3‐Benzodiazepine derivatives: 1‐(4‐Aminophenyl)‐3,5‐dihydro‐3‐N‐ethylcarbamoyl‐5‐methyl‐7,8‐methylenedioxy‐4H‐2,3‐benzodiazepin‐4‐one was synthesized, and its enantiomers were separated by chiral HPLC. Pharmacological evaluation of each enantiomer showed that (S)‐(−)‐5 appears to be more potent than its optical antipode (R)‐(+)‐5 in an AMPA receptor binding assay.