Desenvolvimento de emulgéis à base de colágeno e gelatina de Oreochromis niloticus associados a extrato de Chlorella vulgaris e nitrato de prata para o tratamento de queimaduras em modelo murino

Abstract

The pharmacological treatments available for burns have limited action to control microbial proliferation and this gap motivates research to develop more effective therapeutic agents capable of directly stimulating the skin healing process. The aim of this study was to develop and characterize emulsions based on collagen and gelatin from Nile tilapia skin associated or not with Chlorella vulgaris extract and silver nitrate for the treatment of burns. Collagen and gelatin extracted from tilapia skin, and total crude extract (Ebt) of C. vulgaris were physicochemically characterized and used in the formulation of emulgels. Three formulations of emulgels were developed: collagen (COL) + gelatin (GEL) (E1), COL + GEL + Ebt 1% (E2) and COL + GEL + Ebt 1% + silver nitrate 0.1% (E3). As controls, silver sulfadiazine and blood clot were used. The emulgels were characterized by FTIR, rheology and electrophoresis, in vitro cytotoxicity using keratinocyte and fibroblast lines, and in vivo healing potential in a burn model. For the in vivo assay, male albino Wistar rats received general anesthesia, had the dorsal region shaved and 5 burns were induced per animal, one for each treatment. The burns were treated with the formulations and the reapplication of the treatments was done every 2 days. Individual photographic records were made of the lesions at the experimental times of 0, 1, 3, 7, 14, 21 and 28 days. After euthanasia, excisional necropsy, fixation and histological processing were performed. The description and quantification of inflammatory and repair criteria were performed in a blinded analysis. COL and GEL showed good physicochemical characteristics. Ebt showed a good protein profile, antioxidant activity and moderate in vitro cytotoxicity. E1, E2 and E3 presented similar physicochemical and rheological characteristics and varied cytotoxicity profile. In the in vivo study, there was no significant difference in the percentage of lesion closure between groups and controls. However, microscopic analysis showed higher scores for polymorphonuclear cells in E1 and for neovascularization and re-epithelialization in E3. The COL+GEL+Ebt+AgNO3 emulgel has potential as a formulation applied to the healing of thermal burns, requiring further clinical studies.