The aging analysis of natural rubber-Copaifera oblongifolia extract membranes.

Natural rubber (NR), derived from Hevea brasiliensis, has properties for biomedical applications. Several studies indicate that these properties can be amplified when we associate another bioproduct. However, there are no studies of aging aspects of this biomaterial regarding changes in functionality, structure and composition. The objective was to evaluate the aging process of natural rubber membranes - copaiba (NRC) subjected to controlled conditions of time, light and presence of oxygen. The NRC was prepared and stored in the presence or absence of light and vacuum, for periods of 30, 60 and 90 days. Subsequently, the membranes were characterized through the techniques of wettability, infrared spectroscopy, thermal analysis, scanning microscopy and antioxidant activity. The wettability analysis, showed that NRC membranes both in the zero time and in the aging time were hydrophilic. Through thermogravimetric analysis and differential exploratory analysis the membranes remained thermally stable. The scanning electronic microscopy, indicated no morphological alterations during the observed period. After 90 days, the packaged membranes showed satisfactory antioxidant activity. Our results suggest that the membranes were resistant to the storage period, since they maintained their chemical, thermal, morphological and antioxidant characteristics. Hence, it corroborates to use of membranes as a possible curative for biomedical applications.

NATURAL RUBBER - PROPOLIS MEMBRANE IMPROVES WOUND HEALING IN SECOND-DEGREE BURNING MODEL.

Our aim was to evaluate effects of natural rubber membrane (NR) associated with aqueous propolis extract (P) on the wound healing in rats burn model. The membranes were characterized for wettability and pore presence after the membrane preparation by casting the liquid solution in Petri dishes, at different temperatures (27 and 60 °C). Male Wistar rats were divided into treatment groups (n = 5 per group: control without treatment, silver sulfadiazine, NR, NRP) initiated immediately after second-degree burn and maintained during 10 days. The NRP membranes presented hydrophilic and porous characteristics. Macroscopic analysis from lesions showed that all groups presented crust formation. At the end of the experiment, the lesions treated with NRP membranes prepared at 60 °C had a higher regression percentage indicating a faster wound healing. The biopsies showed that the treatment with the NRP membranes induced a wound healing with collagen production, angiogenesis, reepithelization, and a small number of inflammatory cells, characterized by the crust detachment and the epithelium formation. In conclusion, NRP membranes are promising as a dressing for the burns treatment since were able to accelerate the healing process and tissue repair without the curative switch.

Effects of hyperbaric oxygen on Leishmania amazonensis promastigotes and amastigotes.

In the present study, we evaluated the effects of hyperbaric oxygen (HBO) exposure in both Leishmania amazonensis life stages (promastigotes and amastigotes) and on macrophage cultures infected with the parasite. HBO treatment protocols, which can be tolerated by humans and animals, induced irreversible metabolic damage and affected parasite morphology, growth and ability to transform. The observation that the antioxidant N-acetylcysteine (NAC) prevents some of these deleterious effects indicated an involvement of oxidative stress during parasite HBO exposure. In addition, HBO exposed L. amazonensis-infected macrophage cultures showed reduction of the percentage of infected cells and of the number of intracellular parasites per cell. Thus, the demonstration that HBO, a therapy used in the management of different diseases, is toxic for both L. amazonensis life stages and can alter macrophage susceptibility to the infection encourages further studies of this therapy in animal models of Leishmania infection.