Tilápia do Nilo (Oreochromis niloticus) como fonte de resíduos para extração de glicosaminoglicanos antioxidantes

Abstract

Within the possibilities of the use of residues from Nile Tilapia filleting (Oreochromis niloticus) is the extraction of glycosaminoglycans (GAGs) antioxidant as an alternative option to cancerinducing synthetics. This work had evaluated the distribution, the molecule characteristics, and the in vitro antioxidant capacity of the GAGs obtained by the skin, gill, eye, intestine and gonad of specimens cultivated at the Aquaculture Station/UFC. The dehydrated and quantified residues were digested with papain and its GAGs characterized by yield, metachromasia using dimethylmethylene blue as indicator, electrophoresis in agarose and polyacrylamide gels comparing to heparin, chondroitin-4/6-sulfate, dermatan sulfate and/or sulfated dextran visualized with toluidine blue or stains all, infrared spectroscopy, and in vitro antioxidant capacity of scavenging the radical DPPH, chelation of the ferrous ion, and total antioxidant capacity taking BHT, EDTA, and Ascorbic acid as standards, respectively. The results showed a larger volume of dehydrated residues of the external anatomy (1.56%) in relation to the abdominal cavity (0.11%). Gill – arc and basis (1.28 ± 0.06% and 0.46 ± 0.07, respectively) it was the main source in GAGs, followed by gonad (0.40 ± 0.08%), intestine (0.36 ± 0.10%), skin (0.18 ± 0.02%) and eye (0.16 ± 0.03%). Biochemistry and structural techniques used suggested GAGs with distribution, complex and heterogenous composition, metachromatics (sulfation) and with approximately 40 kDa of molecule weigh considering all evaluated samples, whose profiles had indicated in gill chondroitin-4/6-sulfate; in skin, chondroitin/dermatan; in eye, dermatan and hyaluronic acid; in intestine, heparan more expressive than dermatan, besides hyaluronic acid and in gonad, chondroitin-4/6-sulfate, heparan and/or hyaluronic acid. Evaluative tests of in vitro antioxidant activity of the gill basis constituents GAGs showed that these possess considerable effects over the scavenging of the radical DPPH and in the chelation of the ferrous ion, with inhibitions as powerful as the used control BHT and EDTA, respectively, suggesting parental action in the combat of the oxidative stress. Therefore, the Nile Tilapia possesses distribution and complex biochemistry of GAGs and the residue of the gill basis reveals them as powerful in vitro antioxidants agents.