RESUMO
ß-Hairpin peptidomimetics mimicking the interaction sites of the platelet receptor glycoprotein (GP)Ibα with von Willebrand factor (vWF) were synthesised and evaluated for their ability to increase platelet velocity under high shear conditions and to inhibit shear-induced platelet aggregation. A cyclic and bridged dodecapeptide 2e containing a heterochiral diproline motif was identified as a lead compound for the generation of a novel class of potential antiplatelet agents.
Assuntos
Peptidomiméticos/farmacologia , Adesividade Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/química , Complexo Glicoproteico GPIb-IX de Plaquetas/química , Sítios de Ligação , Humanos , Peptidomiméticos/química , Agregação Plaquetária/efeitos dos fármacos , Complexo Glicoproteico GPIb-IX de Plaquetas/metabolismo , Ligação Proteica , Estrutura Secundária de Proteína , Fator de von Willebrand/química , Fator de von Willebrand/metabolismoRESUMO
The aim of this study was to compare protein-loaded inhalable microparticles manufactured using a range of biocompatible polymers including hydroxypropyl cellulose (HPC), chitosan, hyaluronic acid, alginate, gelatin, ovalbumin and poly(lactide-co-glycolide) (PLGA). Spray-drying was used to prepare microparticles containing bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC). Particles of respirable size and high protein loading were obtained. No evidence of BSA degradation was seen from PAGE analysis. The microparticles were mixed with mannitol as a carrier and powder aerosolization was assessed with a multi-dose dry powder inhaler (DPI) using a multi-stage cascade impactor. The mass median aerodynamic diameter (MMAD) ranged between 2.9 and 4.7 microm. Potential polymer toxicity in the lungs was compared by impinging the particles on Calu-3 monolayers and assessing the cytotoxicity, induction of cytokine release, changes in transepithelial permeability and electrical resistance. No toxic effects were observed with most of the polymers though some evidence of compromised cell monolayer integrity was seen for PLGA and ovalbumin. PLGA and gelatin microparticles caused a significant increase in IL-8 release. Of the polymers studied, PLGA showed the greatest toxicity. Certain polymers showed particular promise for specific protein delivery needs in the lungs, such as HPC to improve flow properties, sodium hyaluronate for controlled release, and chitosan and ovalbumin for systemic delivery.