Encapsulation of salicylic acid in acylated low molecular weight chitosan for sustained release topical application

Pharmaceutical Properties of the Phloretin-4,4'-Bipyridine Cocrystal: Structure Analysis, Drug Release Profile, and Antioxidant Activity Research

To improve the water solubility of phloretin, we synthesized the Phl-4B cocrystal using the solvent evaporation method. Various analytical techniques including powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), 1HNMR, and single-crystal X-ray diffraction (SCXRD) were employed to evaluate the crystal thermodynamics and structure. The results of PXRD and SCXRD showed that it was a new cocrystal crystallized in the P-1 space group of the triclinic system. Thermal analysis confirmed the purity of the Phl-4B cocrystal. The equilibrium solubility of the Phl-4B cocrystal in pH 1.2 was improved. In vitro simulated digestion experiments indicated that the release of the Phl-4B cocrystal followed Fick diffusion. The stability activity of phloretin after pharmaceutical cocrystallization was improved. The antioxidant of the Phl-4B cocrystal was better than that of pure Phl.

Physicochemical Properties and Release Study of Antimetabolite-Incorporated Stearoyl Chitosan

Stearoyl chitosan (SC), derived from the acylation of chitosan, contributes to the efficiency of drug delivery systems because of its structure, which accommodates the drug in a particle. Nonetheless, its role in chemotherapy has been largely unexplored. The present study involves the synthesis of stearoyl chitosan through the reaction of depolymerized chitosan with stearoyl chloride under mild reaction conditions. The resulting compound was subjected to structural analysis utilizing Fourier-transform infrared (FTIR) spectroscopy, 1H NMR, and X-ray diffraction (XRD) spectroscopy. The dispersion of SC molecules in phosphate-buffered saline (PBS) forms SC nanoparticles. The best dispersion of SC in the solution was achieved at a 1:60 chitosan-to-stearoyl chloride weight ratio. Three antimetabolite drugs, methotrexate, pemetrexed, and raltitrexed, were selected to examine the loading efficacy of SC. Pemetrexed had the highest drug-loading value of 36.8% among the three antimetabolites incorporated into SC, along with an encapsulation efficiency of 85.1%. The size of SC loaded with antimetabolites ranged from 225 to 369 nm, and their spherical form was verified via a transmission electron microscope. The in vitro release study showed that SC demonstrated controlled drug release, suggesting that SC nanoparticles have significant promise as a delivery strategy for chemotherapy.

Improvement of salicylic acid biological effect through its encapsulation with silica or chitosan

Attacks of necrotrophic and biotrophic fungi affect a large number of crops worldwide and are difficult to control with fungicides due to their genetic plasticity. Encapsulation technology is a good alternative for controlling fungal diseases. In this work, encapsulated samples of salicylic acid (SA) with silica (Si:SA) or chitosan (Ch:SA) at three different ratios were prepared by spray drying, and morphological and physicochemical characterised. Therefore, size distribution, specific surface area, thermal stability, encapsulation efficiency, and in-vitro SA release were determined. Biological activity of encapsulated samples were tested against different fungi of agricultural interest at various concentrations (0-1000 µM). Treatments prepared with the lowest ratios for both capsules, were found to have the best antifungal effect in an in vitro system, inhibiting the mycelial growth of Alternaria alternata, Botrytis cinerea, Fusarium oxysporum and Geotrichum candidum. Similarly, treatments with the lowest ratios of both encapsulated samples reduced free SA toxicity on Arabidopsis thaliana seeds. In this system, plants treated with capsules had higher root and rosette development than those treated with free SA. In conclusion, a product with a great potential in agriculture that shows high antifungal capacity and low toxicity for plants have been developed through a controlled and industrially viable process.

Encapsulation of Vitamin E and Soy Isoflavone Using Spiral Dextrin: Comparative Structural Characterization, Release Kinetics, and Antioxidant Capacity during Simulated Gastrointestinal Tract

Spiral dextrin subfraction (SD-40) obtained through enzyme debranching and gradient ethanol precipitation could interact with vitamin E (VE) or soy isoflavone (SIO) to form V-type inclusion complexes. The formation of two inclusion complexes was confirmed by Fourier transform-infrared spectroscopy, atomic force microscopy, and differential scanning calorimetry. In this study, an in vitro gastrointestinal model was used to investigate the breakdown of inclusion complexes and release behavior of bioactive compounds. The results indicated that the two inclusion complexes exhibited a controlled and sustained release behavior during digestion. In addition, the SD-40/VE inclusion complex presented higher stability and stronger antioxidant capacity than the SD-40/SIO inclusion complex. Furthermore, the first and zero order models were applied to understand the release kinetics of VE and SIO from inclusion complexes in the stomach, whereas the first order model was chosen to describe the release of VE and SIO from inclusion complexes in the intestine.