Structural study of fucoidan from sea cucumber Acaudina molpadioides: A fucoidan containing novel tetrafucose repeating unit

Structure of fucoidan from sea cucumber Acaudina molpadioides (Am-FUC) was investigated in this study. Low molecular weight polysaccharide of Am-FUC (Am-LMW) was prepared by enzymatic degradation and assayed by nuclear magnetic resonance. According to the structure of Am-LMW, and referring to previously reported information of Am-FUC oligosaccharides, the structure of Am-FUC was elucidated as [→3-α-l-Fucp-1 → 3-α-l-Fucp2,4(OSO3-)-1 → 3-α-l-Fucp-1 → 3-α-l-Fucp2(OSO3-)-1→]n. Compared to other investigated fucoidans, which also consist of tetrafucose repeating units with 1 → 3-linkages, Am-FUC contains a novel repeating unit distinctive in sulphation pattern.