A Comparative Study on the Thermal Decomposition Behaviors between β-Cyclodextrin and Its Inclusion Complexes of Organic Amines

Physicochemical characterization and in vitro biological evaluation of solid compounds from furazolidone-based cyclodextrins for use as leishmanicidal agents

The discovery of new drugs and dosage forms for the treatment of neglected tropical diseases, such as human and animal leishmaniasis, is gaining interest in the chemical, biological, pharmaceutical, and medical fields. Many pharmaceutical companies are exploring the use of old drugs to establishing new drug dosage forms and drug delivery systems, in particular for use in neglected diseases. The formation of complexes with cyclodextrins is widely used to improve the stability, solubility, and bioavailability of pharmaceutical drugs, as well as reduce both the toxicity and side effects of many of these drugs. The aim of this study was to characterize solid compounds obtained from the association between furazolidone (FZD) and β-cyclodextrin (β-CD) or hydroxypropyl-β-cyclodextrin (HP-β-CD). The solid compounds were prepared in molar ratios of 1:1 and 1:2 (drug:CD) by kneading and lyophilization. Molecular docking was used to predict the preferred relative orientation of FZD when bound in both studied cyclodextrins. The resulting solid compounds were qualitatively characterized by scanning electron microscopy (SEM), thermal analysis (DSC and TG/DTG), X-ray diffraction (XRD), Raman spectroscopy with image mapping (Raman mapping), and ¹³C nuclear magnetic resonance spectroscopy (¹³C NMR) in the solid state. The cytotoxicity of the compounds against THP-1 macrophages and the 50% growth inhibition (IC₅₀) against Leishmania amazonensis promastigote forms were subsequently investigated using in vitro techniques. For all of the solid compounds obtained, the existence of an association between FZD and CD were confirmed by one or more characterization techniques (TG/DTG, DSC, SEM, XRD, RAMAN, and ¹³C NMR), particularly by a significant decrease in the crystallinity of these materials and a reduction in the melting enthalpy associated with furazolidone thermal events. The formation of more effective interactions occurred in the compounds prepared by lyophilization, in a 1:2 molar ratio of the two CDs studied. However, the formation of an inclusion complex was confirmed only for the solid compound obtained from HP-β-CD prepared by lyophilization (LHFZD1:2). The absence of cytotoxicity on the THP-1 macrophage lineages and the leishmanicidal activity were confirmed for all compounds. MHFZD1:2 and LHFZD1:2 were found to be very active against promastigote forms of L. amazonensis, while all others were considered only active. These results are in line with the literature, demonstrating the existence of biological activity for associations between drugs and CDs in the form of complexes and non-complexes. All solid compounds obtained were found to be promising for use as leishmanicidal agents against promastigote forms of L. amazonensis.

Electrospun poly(ε-caprolactone) matrices containing silver sulfadiazine complexed with β-cyclodextrin as a new pharmaceutical dosage form to wound healing: preliminary physicochemical and biological evaluation

Cooperation between researchers in the areas of medical, pharmaceutical and materials science has facilitated the development of pharmaceutical dosage forms that elicit therapeutic effects and protective action with a single product. In addition to optimizing pharmacologic action, such dosage forms provide greater patient comfort and increase success and treatment compliance. In the present work, we prepared semipermeable bioactive electrospun fibers for use as wound dressings containing silver sulfadiazine complexed with β-cyclodextrin in a poly(Ɛ-caprolactone) nanofiber matrix aiming to reduce the direct contact between silver and skin and to modulate the drug release. Wound dressings were prepared by electrospinning, and were subjected to ATR-FT-IR and TG/DTG assays to evaluate drug stability. The hydrophilicity of the fibrous nanostructure in water and PBS buffer was studied by goniometry. Electrospun fibers permeability and swelling capacity were assessed, and a dissolution test was performed. In vitro biological tests were realized to investigate the biological compatibility and antimicrobial activity. We obtained flexible matrices that were each approximately 1.0 g in weight. The electrospun fibers were shown to be semipermeable, with water vapor transmission and swelling indexes compatible with the proposed objective. The hydrophilicity was moderate. Matrices containing pure drug modulated drug release adequately during 24 h but presented a high hemolytic index. Complexation promoted a decrease in the hemolytic index and in the drug release but did not negatively impact antimicrobial activity. The drug was released predominantly by diffusion. These results indicate that electrospun PCL matrices containing β-cyclodextrin/silver sulfadiazine inclusion complexes are a promising pharmaceutical dosage form for wound healing.

Controlled release of retinyl acetate from β-cyclodextrin functionalized poly(vinyl alcohol) electrospun nanofibers

Retinyl acetate (RA) was effectively incorporated into electrospun nanofibers of poly(vinyl alcohol) (PVA) containing β-cyclodextrin (β-CD) in order to form inclusion complexes for encapsulation to prolong shelf life and thermal stability. The physical and thermal properties of encapsulated RA were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The nanofibers of PVA/RA and PVA/RA/β-CD exhibited bead free average fiber diameters of 264 ± 61 and 223 ± 49 nm, respectively. The surface chemistry of the functional nanofibers was investigated by X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) demonstrated different thermal stabilities between the bioactive and the polymer, with and without β-CD. Square-wave voltammogram peak current changes were used to follow the release kinetics of RA from the nanofibers. Results indicate that RA coated inside PVA/β-CD nanofibers was protected against oxidation much better than RA in PVA nanofibers and should extend the shelf life. In addition, RA encapsulated in the PVA/β-CD had better thermal stability than PVA nanofibers.