Surface-modified polyacrylonitrile nanofibers as supports

Polyacrylonitrile nanofibers (PAN-nfs) are one of the most studied nanofibres because of their excellent characteristics, such as good mechanical strength, chemical resistance, and good thermal stability. Due to the easy dissolution in polar organic solvents, PAN-nfs are mostly produced via electrospinning technique. The electrospun PAN-nfs surfaces are relatively in-active and hydrophobic, and, therefore, hinder some potential applications; however, chemical surface modification reactions, such as amination, reduction, hydrolysis, and amidoximation, have been carried out on them. These reactions bring about functional groups, such as amine, hydroxyl, carboxylic, imine etc, to the surface PAN-nfs and invariably make their surfaces active and hydrophilic. The surface-modified PAN-nfs have been used as supports for organic compounds, enzymes, and antibodies in biological studies. They have also been used for immobilization of various organic ligands for adsorption of metal ions in water. Furthermore, because of their ability to complex metal ions, several surface-modified PAN-nfs have also been used as supports for transition metal catalysts in Fenton’s chemistry.IS

Preparation and in vitro evaluation of Allopurinol-Gelucire 50/13 solid dispersions

The rate-limiting step to absorption of drugs from the gastrointestinal tract is often dissolution from the dosage form. Allopurinol is a commonly used drug in the treatment of chronic gout or hyperuricaemia associated with leukaemia, radiotherapy, anti-neoplastic agents. One of the major problems with allopurinol is that, it is practically insoluble in water, which results in poor bioavailability after oral administration. In the present study, solid dispersions of allopurinol were prepared by solvent evaporation method, kneading method, co-precipitation method, co-grinding method and closed melting method to increase its water solubility. In the present study amphiphilic carrier like gelucire 50/13 was used in the ratio of 1:1, 1:2 and 1:4. Prepared solid dispersions were characterized in the liquid state by phase solubility studies and in the solid state by Differential Scanning calorimetric analysis, Powder X-ray diffractometry and Fourier Transform Infrared spectroscopy. The aqueous solubility of allopurinol was preferential by the presence polymer with increasing concentration. Solid state characterizations indicated that allopurinol was present as an amorphous material and entrapped in polymer matrix.Mathematical modeling of in vitro dissolution data indicated the best fitting with Korsemeyer-Peppas model and the drug release kinetics primarily as Non-Fickian diffusion. Therefore, the current study showed that gelucire 50/13 has a significant solubilizing effect on allopurinol.Keywords: Allopurinol, gelucire 50/13, closed melting-method, co-grinding, dissolution study, powder X-ray diffraction analysi

Conformational analysis and in vitro immunomodulatory and insulinotropic properties of the frog skin host-defense peptide rhinophrynin-27 and selected analogs

© 2019 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM) The study investigates conformational analysis and the in vitro cytokine-mediated immunomodulatory and insulin-releasing activities of rhinophrynin-27 (ELRLPEIARPVPEVLPARLPLPALPRN; RP-27), a proline-arginine-rich peptide first isolated from skin secretions of the Mexican burrowing toad Rhinophrynus dorsalis (Rhinophrynidae). In both water and 50% trifluoroethanol-water, the peptide adopts a polyproline type II helical conformation with a high degree of deviation from the canonical collagen-like folding and a pronounced bend in the molecule at the Glu13 residue. Incubation of mouse peritoneal cells with RP-27 significantly (P < 0.05) inhibited production of the pro-inflammatory cytokines TNF-α and IL-1β and stimulated production of the anti-inflammatory cytokine IL-10. The peptide significantly (P < 0.01) stimulated release of insulin from BRIN-BD11 rat clonal β-cells at concentrations ≥ 1 nM while maintaining the integrity of the plasma membrane and also stimulated insulin release from isolated mouse islets at a concentration of 10−6 M. Increasing the cationicity of RP-27 by substituting glutamic acid residues in the peptide by arginine and increasing hydrophobicity by substituting alanine residues by tryptophan did not result in analogues with increased activity with respect to cytokine production and insulin release. The combination of immunosuppressive and insulinotropic activities together with very low cytotoxicity suggests that RP-27 may represent a template for the development of an agent for use in anti-inflammatory and Type 2 diabetes therapies