Avaliação do potencial antioxidante de Condroitim sulfato extraído das vísceras de tilápia Oreochromis niloticus

Abstract

Glycosaminoglycans are polysaccharides present in the cell surface and extracellular matrix of the vast majority of animals. They perform several biological functions, such as cell growth, differentiation, antioxidant, neuroprotec and others. Among glycosaminoglycans, chondroitin sulfate (CS) stands out for its antioxidant effect and can also be found in many fish species, such as tilapia (Oreochromis niloticus) whose cultivation represents an important economic activity in Natal (RN / Brazil). ), eliminating a big quantity of viscera as a waste of its production, daily. Thus, the following study uses the tilapia wastes that have been obteined in free markets in city of Natal, as raw material for the extraction and purification of chondroitin sulfate, in addition to evaluete its antioxidant effect. For this, the residues were exposed to an enzymatic proteolyse process, followed by complexation and decomplexing with Lewatit resin, obtaining a pool of glycosaminoglycans that have been used in purification procedures like acetone fractionation and ion exchange chromatography, accompained by agarose gel electrophoresis and enzimatic degradation. Subsequently, antioxidant tests were performed to quantify the ability of CS to inhibit reactive species intracellular and in vitro, since the imbalance in their quantities has a role in clinical conditions such as autoimmune, neurodegenerative diseases and cancer. For this, methods such as inhibition of intracelular ROS (DCFH-DA), chelation of ferrous and cupric ions, inhibition of superoxide and hydroxyl radicals, in addition to inhibition of nitric oxide and lipid peroxidation were used. As a result, it was possible to observe that in each kilogram of tilapia viscera dry mass it is possible to extract approximately 69mg of purified chondroitin sulfate, being 59% composed of chondroitin-4-sulfate. By observing the values obtained in the antioxidant tests, it was possible to highlight an inhibition of up to 52% of the reactive intracellular species in culture of RAW 264.7 cells, without demonstration of cytotoxicity up to the concentration of 200mg /mL of chondroitin. The other tests showed that this inhibition occurs due to several factors, ranging from the inhibition of metals and free radicals (p<0,05), to the probable participation in secondary pathways, such as the activation of antioxidant proteins. The results obtained in this study strengthen the extraction and use of glycosaminoglycans, especially chondroitin sulfate, helping to understand the biological effects of chondroitins from multiple sources, emphasizing their antioxidant effect and providing a disposal alternative for the biological waste produced by commercial tilapia production, opening perspectives for possible uses of this molecule in research and industry.