ViabilizaÃÃo da heparina como suporte para carrear gentamicina

AUTOR(ES)

Givanildo Bezerra de Oliveira

DATA DE PUBLICAÇÃO

2002

RESUMO

Many polymers used as drug carriers in controlled delivery systems are polysaccharides. This work propose the use of glycosaminoglycan heparin as carrier for the aminoglycosidic antibiotic gentamicin. Due to their chemical feature, these compounds possess an intrinsic ionic affinity, nevertheless, a carbodiimide was used to promote covalent binding (amide bond) between these molecules. The heparin-gentamicin conjugate after dialysis presented antimicrobial activity in vitro. This conjugate presented electrophoretic migration slower than single heparin. It was stable when submitted to enzymatic degradation by heparin lyases. The infrared spectra of this conjugate showed characteristic amide bands, suggesting the presence of covalent binding. Furthermore, the effect of increasing carbodiimide concentrations upon physicochemical and biological properties of the heparin was observed. The results showed that the activation affect the toluidine blue and methylene blue dyes fixation activity. However, this effect was dependent on the activating agent concentration. These activated heparins did not present the slow moving component, which in native heparin correspond to the highest molecular weight and electric charge fraction, when submitted to electrophoresis in a barium acetate/diaminopropane acetate discontinuous system. This observation was in accordance with the anticoagulant activity assays, where the modified heparins had its anticoagulant activities reduced. The degradation tests performed with heparin lyases showed that modified heparins were less degraded with increasing activating agent concentration. Thus it could be observed that carbodiimide activated heparin does not possess the same physicochemical and biological properties as native heparin. In addition, the dye fixation activity can be a useful tool to evaluate the biological activity of the modified heparins. Based on these information one can assume that, under perfect activation and immobilization conditions, it is possible to obtain heparin conjugates which can present the anticoagulant and/or antithrombotic activities and the antimicrobial activity of gentamicin

ASSUNTO(S)

bioquimica gentamicina carbodiimida polissacarÃdeos

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