Characterization of exopolysaccharides produced by microalgae with antitumor activity on human colon cancer cells.

The physicochemical characteristics, antioxidant and antitumor activities of partial purified exopolysaccharides from microalgae Chlorella pyrenoidosa FACHB-9, Scenedesmus sp. and Chlorococcum sp. were investigated. The molecular weights were 1.94 × 105, 7.39 × 103 and 3.24 × 104 g/mol, respectively. Monosaccharide analysis indicating that these exopolysaccharides consisted of ten different kinds of sugars and derivatives, respectively. Furthermore, they exhibited obvious free radicals scavenging abilities, which reached to 55.2-71.4% and 63.1-77.5% on DPPH and hydroxyl radicals, respectively. Moreover, the antitumor effects were investigated using human colon cancer cell lines HCT116 and HCT8. The results showed that they had significant antitumor effects considering the inhibitory effects on cell viabilities (17.2-19.2% on HCT116, and 22.9-38.6 on HCT8, respectively), and could decrease the colony amounts (21-42.8% on HCT116, and 11.5-35.2% on HCT8, respectively) at the tested dosage. Thus, these exopolysaccharides may be worth further investigating as effective potential antitumor agents.