Avaliação da atividade antinociceptiva de uma fração polissacarídica sulfatada da alga marinha verde Ulva lactuca (Linnaeus)

Abstract

Marine algae are abundant sources of sulfated polysaccharides with various biological activities, thereby altering its biomolecules are great of commercial interest, especially in the pharmaceutical and food industries. This study aimed to evaluate the effects of a sulfated polysaccharidic fraction from green seaweed Ulva lactuca in classical models of nociception. The total sulfated polysaccharides were extracted by enzymatic digestion (6h; 60°C) and then purified by ion exchange chromatography on DEAE-cellulose. The antinociceptive activity was evaluated by the writings of abdominal constrictions induced by acetic acid, formalin tet and hot plate. The elution profile indicated the separation of three different fractions (FI, FII and FIII) eluted at 0.50, 0.75 and 1.00 M of NaCl, respectively. The fraction with higher yield was used in the assays (FII – PS-Ul). We used male Swiss mice were pre-treated with PS-Ul (1, 3 or 9 mg/kg, i.v) or sterile saline (iv) 30 min before receiving pain stimuli (acetic acid 0.8% or 2% formalin) or heat exposure. Subchronic toxicity test was conducted in groups of 6 mice (males), which received: saline (0.15 M, i.p.) and PS-Ul (9 mg/kg, i.p.) for 14 consecutive days. The PS-Ul was able to reduce (p<0.05) the number of writhing induced by 0.8% acetic acid (48.19; 42.66 and 39.89%, for 1, 3 and 9 mg/kg, respectively). PS-Ul did not reduced the licking time in the first phase (neurogenic) of the test. However, in the second phase (inflammatory) of the test, PS-Ul reduced (p<0.05) the licking time by 72.06; 35.99 and 35.66%, for 1, 3 and 9 mg/kg, respectively. PS-Ul did not increase the reaction time in the 30, 60 and 90 min intervals. Therefore, PS-Ul isolated from U. lactuca presented antinociceptive action through peripheral mechanisms. Finally, the results showed that the administrations of PS-Ul did not show to differences in body mass (p>0.05). Additionally, the PS-Ul did not produce changes in organ weights (heart, liver and kidney) in relation to body mass of animals. No change for liver biochemical tests (AST and ALT) or renal function was also observed (p>0.05). Thus, the green seaweed Ulva lactuca sulfated polysaccharide present security and antinociceptive activity.