Fucoidan from sea cucumber Holothuria polii: Structural elucidation and stimulation of hematopoietic activity.

The structural elucidation of polysaccharides is essential for understanding their structure-bioactivity relationship and related drug development. In this study, fucoidan (Fuc) was extracted and purified from sea cucumber Holothuria polii. Its sulfate content was 39.5 ± 1.4%, and the "weight-average" molecular mass was 103.1 ± 2.8 kDa. The primary structure of Fuc was clarified using a combination of acid degradation, tandem mass spectrometry, and nuclear magnetic resonance spectroscopy analysis. As a result, Fuc was found to be composed of a tetrafucose repeating unit [→3-α-l-Fucp-1 → 3-α-l-Fucp2(OSO)-1 → 3-α-l-Fucp2(OSO)-1 → 3-α-l-Fucp2,4(OSO)-1→]. The stimulating hematopoiesis was further evaluated in a mouse model induced by cyclophosphamide. Based on these findings, intraperitoneally administered Fuc may accelerate the recovery of white blood cells and neutrophils, in which its activity exceeded that of recombinant human granulocyte colony-stimulating factor (rhG-CSF). Meanwhile, in the background of cyclophosphamide-induced immunosuppression, treatment with Fuc reduces platelet aggregation caused by CTX, so it might have the effect of reducing the risk of thrombosis. Therefore, Fuc can be exploited as potentially promising stimulator of hematopoiesis in the future.