Estudo toxicológico e das atividades antiinflamatória, analgésica e antiangiogênica da cartilagem de tubarão

Abstract

Shark cartilage has been largely used as a dietary supplement in case of chronic diseases like osteoarthritis, reumathoid arthritis, osteoporosis, psoriasis and also to treat câncer. The aim of the present work was to investigate the toxicity of the crude shark cartilage, as well as the anti-inflammatory and analgesic activities of its hydrosoluble fraction (HF). The analgesic activity of the semi-purified fractions (SF) obtained from gel filtration chromatography on Sephadex G-100 of HF was also studied. The chromatographic profile of the HF on Sephadex G-100 revealed two peaks, I and II, rich in proteins, with molecular weights of 103 and 1,9 KDa respectively. The LD5o of shark cartilage, for us used, was not determinated because of its low solubility in water. However, no acute toxicity or mortality was observed after administration of the shark cartilage up to 2 g/kg orally or intraperitoneally as an aqueous suspension. The subacute treatment of Wistar rats with shark cartilage 1 g/kg, orally, during 30 days did not promote alterations of the blood biochemistry or cell counting determinations. The treatment of Wistar rats, of both sexs, with shark cartilage 100, 200 and 500 mg/kg, orally, during 90 days did not reveal any chronic toxicity or deaths. In the same way, in regard to reprodutive function, shark cartilage did not alter the conception and/or gestation. Nevertheless, few litters (about 10%) exhibited deficiency in the process of development, detected by the incomplete opening of the eyelid. The HF (20 mg/kg, p.o.) decresed the rat paw edema induced by carrageenan or dextran. Therefore, the HF seems to interfere on the inflammatory process presenting a great number of cells, and also can exert a stabilizer action on cell membranes. The next step was then to study the effects of HF on the cutaneous vascular permeability induced by histamine and serotonine in rats. The HF (2 mg/kg, p.o.) significantly decresed (P < 0,01) the dye extravasation induced by histamine. Thalidomide did not significantly modify the HF effect. The HF was also tested on the neutrophil migration induced by carrageenan or N-formyl-methionyl-leucyl phenylalanine (FMLP) in rat peritoneal cavity. The HF (10 and 20 mg/kg, p.o.) significantly decreased neutrophil migration induced by carrageenan. However, at the same doses, HF showed a high inhibitory effect on neutrophil migration induced by FMLP. The HF seems to block the release of chemotactic factors by resident cells and similarly to dexamethasone it inhibits the last step of neutrophil migration. In the present study, the HF (10 and 20 mg/kg, p.o.) also significantly decreased (P < 0,01) the angiogenesis induced by complete Freund’s adjuvant in rats. The analgesic activity of the HF was evaluated in three different models of nociception in mice. The HF (1 mg/kg, p.o.) decreased (P < 0,05) the nociception produced by acetic acid and formalin. In the hot plate test, the HF (2 and 10 mg/kg, p.o.) presented no effect. The antinociceptive effect of HF in the writhing test was not potentiated by thalidomide. In the formalin test, the antinociceptive effect of morphine but not that of HF was reversed by naloxone. On the other hand, L-arginine reversed (P < 0,05) the antinociceptive effect of HF. The L-NAME (10 mg/kg, i.p.) when associated to HF, produced an increase in the effect of HF. Also in the formalin test, the semi-purified fraction II (SF II - 0,5 mg/kg, p.o.) significantly inhibited the second phase of the test. However, both fractions (SF I and SF II) potentiaded the antinociceptive effect of L-NAME. The present results confirm the popular use of shark cartilage as analgesic and anti-inflammatory. The active compound is hydrosoluble and presents biochemical characteristics of a protein.