Cytotoxic effects against HeLa cells of polysaccharides from seaweeds.

Polysaccharides extracted from several red and brown seaweeds growing along the South American coasts were evaluated regarding their cytotoxic effects against HeLa cells. Sulfated galactans were isolated and purified from the red algae Bostrychia montagnei (BHW and B4 fractions, 17 and 22% SO3Na, respectively) and Porphyra columbina (PC75 fraction, 15.6% SO3Na). At maximum concentration of 80 microg/mL, these fractions promoted atypical mitoses in HeLa cells, presence of atypical nuclei and blebs. Alginic acid (160.0 microg/mL) isolated from the brown seaweed Laminaria brasiliensis (molar ratio M/G 1.2) and its M and G blocks (40.0 microg/mL; DP = 20), promoted similar morphologic alterations besides the presence of acidophilic material in the cellular cytoplasm and occurrence of multinuclear cells present in the monolayer. The polysaccharide fraction SF isolated from the brown seaweed Sargassum stenophyllum containing mainly fucose and presenting molar ratio of sulfate/sugar 1.9, promoted very accentuated morphologic modifications in HeLa cells at low concentrations. SF (2.5 microg/mL) caused significant alterations in the cellular morphology and reduction of the growth, such effects being dose dependent. At 40.0 microg/mL, accentuated decrease of the number of mitosis illustrations accompanied by an increase in the number of condensed cells, atypical nuclei, number of clusters and blebs. These results demonstrated that among the anionic polysaccharides tested, the sulfated fucans were those which caused greater cytotoxic effects in HeLa cells.