A study of neuroprotective and antioxidant activities of heteropolysaccharides from six Sargassum species.

Heteropolysaccharides were extracted from Sargassum integerrimum (S.I), Sargassum maclurei (S.M), Sargassum naozhouense (S.N), Spiraea thunbergii (S.T), Sargassum hemiphyllum (S.H) and Sargassum fusiforme (S.F), and their neuroprotective effects and antioxidant activities were investigated. It showed that S.I, S.N, S.T and S.F exhibited neuroprotective activities, whereas S.H and S.M did not. For this reason, they were separated by anion-exchange chromatography. It was apparent that the fraction 2 represented the principal difference between the active and non-active compounds. However, it did not correlate with neuroprotective effect. In addition, the results on antioxidant activities showed that the hydroxyl-radical scavenging effect contribute to the neuroprotective effect of S.T and S.N, and the DPPH-radical scavenging effect and reducing power contribute to S.T, S.F and S.I. However, the superoxide-radical scavenging effect did not correlate with neuroprotective activity. The conclusion was that the neuroprotective activity of the family of compounds investigated depended on a variety of factors.