ANTITUMOR SULFATED POLYSACCHARIDES FROM BROWN ALGAE Dictyota caribaea
Sulfated polysaccharides (SP) are a complex group of bioactive molecules able to inhibit tumor growth. SP increase the effectiveness of chemotherapy and reduce some side effects. Brown algae produce SP with several biological activities including antitumor. This work aimed to investigate the antitumor effect of SP from the brown algae Dictyota caribaea (Dc-SP). Dc-SP were extracted with proteolytic enzyme and supernatant was precipitated with increasing concentrations of ethanol. Antiproliferative activity of Dc-SP was tested by the MTT assay against colon cancer (HCT 116) and metastatic melanoma (B16-F10) cell lines. The antitumor effect was evaluated on Swiss mice transplanted with sarcoma 180 tumor and treated i.p. during 7 days with saline or Dc-SP (25 and 50 mg/kg/animal). Dc-SP did not exhibit cytotoxicity in vitro, however the Dc-SP-treated mice depicted up to 50% tumor growth inhibition. Dc-SP treatment induced spleen weight increasing along with intense white pulp disorganization. Furthermore Dc-SP did not depict hepatic toxicity, nephrotoxicity nor leukopenia and did induce increase of platelets count. Altogether, these results represent a promising antitumor host dependent effect induced by Dc-SP.