Cytotoxicity effect of algal polysaccharides on HL60 cells.

The present study shows the cytotoxic effect of three different classes of algal polysaccharides on HL60 cells. Three galactofucans, fucoidan, and glucan were the polysaccharides utilized in this analysis. The parameters used for evaluating cell viability were [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) reduction, protein content, and phosphatase activity. We demonstrated stimulation of phosphatase activity, MTT reduction, and protein content in relation to three types of galactofucans (1, 2, and 3) with different molecular weights (1600, 1200, and 360 kD). However, when HL60 cells were treated with galactofucan type 3, the total protein remained unchanged. Under the same experimental conditions, an expressed increase in the phosphatase activity was detected when galactofucan 3 was utilized. In relation to the mitochondrial function, the stimulation was higher in cells treated with galactofucan type 1. Fucoidan did not have a significant effect on MTT reduction, but protein content was decreased (IC50 around 30 microg/ml). Glucan also activated all the parameters that were analyzed, and this effect was more expressed in the phosphatase activity and in the protein content. This study provides new insights into the cytotoxic action of polysaccharides on HL60 cells and suggests for the first time the possible involvement of phosphatases in this process.