The structure-activity relationship between polysaccharides from Sargassum thunbergii and anti-tumor activity

Polysaccharides derived from Sargassum thunbergii were prepared to investigate the structure-activity relationship between polysaccharides and anti-tumor activity in vitro. Many factors were examined. Overall, STW (polysaccharide extracted by hot water) had the best activity, followed by STJ (polysaccharide extracted by dilute alkali), and then STA (polysaccharide extracted by dilute acid). Location of algae had no effect at 500 mu g/mL and 1000 mu g/mL, while STW-QD (algae collected from Qingdao, China) had the best activity, followed by STW-WZ (algae collected from Wenzhou, China) and STW-LJ (algae collected from Lianjiang, China) and then STW-DL (algae collected from Dalian, China) and STW-RC (algae collected from Rongcheng, China) at 250 mu g/mL. Moreover, molecular weight had no effect at 1000 mu g/mL, while higher molecular weights were associated with better activities at 250 mu g/mL and 500 mu g/mL. Sulfate content had no effect at 1000 mu g/mL, while anti-tumor activities decreased accompanying with the changes of sulfate content. Uronic acid content was an important factor influencing activity. The fractions of STW showed little anti-tumor activity; however, the mixture of the fractions of STW showed approximately 60% inhibition. Overall, these findings suggested that the anti-tumor activity of polysaccharides required multilateral cooperation and that some of the effective components were lost. (C) 2017 Elsevier B.V. All rights reserved.