Antitumor and immunostimulating sulfated polysaccharides from brown algae Dictyota caribaea

Abstract

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). The chemical analyses demonstrated Dc-SP composition was mainly hexose, uronic acid, and sulfate. Dc-SP did not exhibit cytotoxicity against tumor cells in vitro. However, Dc-SP-treated mice with 25 and 50 mg/kg/day depicted Sarcoma 180 tumor growth inhibition of 40% (p < 0.05) and 51% (p < 0.05) respectively comparing to negative control group. Dc-SP treatment induced spleen weight increasing compared to negative control group of 40% (p < 0.05) and 70% (p < 0.05) on mice treated with 25 and 50 mg/kg/day respectively along with intense white pulp disorganization. These results combined support an immunostimulating effect related to in vivo antitumor effect of Dc-SP. This is the first study supporting the antitumor and immunostimulating effects of SP from Dictyota genus. Furthermore, biochemical and hematological analyses of Dc-SP treated mice 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.