Many polysaccharides derived from marine organisms have novel structural characteristics and possess excellent biological functionalities. Holothurian glycosaminoglycan (HG), which is the dominated component of sea cucumber, exhibited multiple bioactivities, such as anticoagulation , immune regulation , anti-cancer  and antiviral activities . The sea cucumber Apostichopus (Stichopus) japonicus is the most popular source of fucosylated chondroitin sulfates (FCS). The different environment and extraction process may influence the fine structural characterization of glycosaminoglycans from the sea cucumbers Apostichopus (Stichopus) japonicas . In our previous study, we isolated a novel glycosaminoglycan from Apostichopus japonicus (AHG) (Mw 98.07 kDa), the structure of which contained a chondroitin sulfate-like backbone together with large quantity of one fucopyranosyl residue attaching to the 3-O position of β-d-glucuronic (GlcA) and 4-O and/or 6-O positions of N-acetyl-β-d-galactosamine (GalNAc). The molar ratio of GlcUA, GalNAc, Fucose (Fuc) and sulfate of AHG was 0.97:1.00:1.13:3.85 . In addition, it was revealed that AHG has not only immunoregulation capability on both innate and adaptive immune in vitro, but also protective effects toward the hematopoietic function of bone marrow and immune organs in myelosuppressed mice . However, the protective effects of AHG on immunological effector cells and organs against immunosuppression and oxidative damage are poorly understood.