Otimização de um método de obtenção dos extratos ricos em polissacarídeos sulfatados da alga Lobophora variegata

Abstract

Lobophora variegata (Lv) seaweed polysaccharides are compounds with antioxidant, immunomodulatory, anti-inflammatory and anticoagulant action. However, their commercial useful does not yet occur. One of the causes is the lack of a good yield of the extraction methods of these polymers. There is a cheap method of extracting polysaccharides from Lv, which uses proteolysis in the presence of saline solution. The seaweed was collected at Pirambúzios beach, south coast of the RN. All collected material was washed, dried, crushed, delipidated and depigmented with 96% alcohol. Subsequently, the seaweeds were assayed for proteolysis (60 °C) in the presence of different concentrations of NaCl (from 0.25M to 3.0M). The samples were dialysed, lyophilized and physico-chemically analyzed. The sugar content of the extracts varied from 67 to 72% and no contamination with proteins was detected. The electrophoretic analyzes confirmed the presence of sulphated polysaccharides (SP) in all samples and that the same polysaccharide populations were obtained under all extraction conditions. The extraction yields ranged from 91 to 169 mg. The condition in which the largest mass was obtained was with 1.5 M NaCl (169 mg). The antioxidant analysis performed by total antioxidant (TAC) and reducing power (RP) also showed the sample obtained in this condition to the detriment of the others, with 10 - 20 μg EAA / mg and 33%, respectively. Using the best concentration found (1.5 M NaCl), the influence of time (from 2 to 8 h) on extraction was evaluated. The best extraction condition was 1.5 M NaCl and 6 hours in a yield of 161 mg. It is concluded that the increase of the NaCl concentration used in the proteolytic digestion increases the yield of the PS obtained, as well as its antioxidant activities tested.