Desenvolvimento, caracterização físico-química e avaliação de filmes de colágeno contendo ácido úsnico no processo de reparo cicatricial em roedores

• Ano de defesa: 2009
• Autor(a) principal: Nunes, Paula Santos
• Orientador(a): Araújo, Adriano Antunes de Souza
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Sergipe
• Programa de Pós-Graduação: Pós-Graduação em Ciências da Saúde
• País: BR
• Palavras-chave em Português: Espectrofotometria; Cicatrização; Ácido úsnico; Colágeno
• Palavras-chave em Inglês: Collagen-based; Usnic acid; Cicatrizacion
• Área do conhecimento CNPq: CNPQ::CIENCIAS DA SAUDE::MEDICINA
• Link de acesso: https://ri.ufs.br/handle/riufs/3682

Disruption of the skin generally leads to an increased fluid loss, infection, hypothermia, scarring, compromised immunity and change in body image; furthermore, large skin damage can cause mortality. Collagen-based film is a potentially useful biomaterial since it is the major constituent of the connective tissue and permit controlled drug release within target tissues. Usnic acid (UA), a dibenzofuran originally isolated from lichens, it can act as an anti-inflammatory, analgesic and antibacterial agent. The purpose of this study was to evaluate the physical-chemical properties and effect of collagen-based films containing usnic acid as a wound dressing for dermal burn healing. Collagen (CL) and usnic acid/collagen-based (UAC) films were characterized using differential thermal analysis (DTA), thermogravimetry (TG/DTG), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Second-degree burn wounds of 1 cm2 were performed in the dorsum of forty-five Wistar rats, assigned into nine groups (n=5): COL animals treated with collagen-based films; PHO animals treated with collagen films containing empty liposomes; UAL animals treated with collagen-based films containing usnic acid incorporated into liposomes. After 7, 14 and 21 days the animals were euthanized. The specimens removed were formalin-fixed, and paraffin-embedded and histological sections were stained in HE and Sirius Red. In the spectrum of UAC, similar bands of the usnic acid are observed, indicating that the polymerization (film formation) did not affect the stability of the drug. Distinctly, DTA curve of UAC did not show an endothermic peak at 201ºC, indicative that the drug was incorporated into the polymeric system. These results were corroborated by the scanning electron microscopy (SEM). The TG/DTG curves of UAC presented a different thermal decomposition profile compared to the individual compounds and CL. These findings suggest the occurrence of molecular dispersion or solubilization of the drug in the collagen film. The specificity revealed that the excipients in the formulation did not interfere with the analysis. The linearity in the range of 2-10 μg/mL presented a correlation coefficient of 0.9994. The method showed excellent repeatability (R.S.D. < 1.0 %). The accuracy, revealed a mean percentage recovery of 100.43 %. The method was robust for the variation of temperature and solvent. The detection and quantization limits were found 0.109 and 0.364 μg/mL. The total rate recovery of the analyte film showed values between 100.4 and 83.2%. Biologycal assays showed on 7th day there was a moderate infiltration of neutrophils, in UAL, distributed throughout the burn wounds, whereas in COL and PHO, the severity of the reaction was slighter and still limited to the margins of the burn wounds. On the 14th day, the inflammatory reaction was less intense in UAL, with remarkable plasma cells infiltratation. On the 21st day, there was unequivocal reduction of the inflammation, which was predominantly composed of plasma cells in all groups, particularly in UAL. The use of collagen-based films containing usnic acid provided more rapid substitution of type-III for type-I collagen on the 14th day, and improved the collagenization density on the 21st day. It was concluded that the use of reconstituted bovine type-I collagen-based films containing usnic acid improved burn healing process in rats.