Structural Features and Digestive Behavior of Fucosylated Chondroitin Sulfate from Sea Cucumbers Stichopus japonicus

Fucosylated chondroitin sulfate from sea cucumber Stichopus japonicus (FCSSJ) has been demonstrated with various biological activities; however, its precise structure is still controversial, and digestive behavior remains poorly understood. FCSSJ was purified, and its detailed structure was elucidated mainly based on the NMR spectroscopic methods. Its main chain was characterized as →4)-β-d-GlcA-(1 → 3)-β-d-GalNAc-(1→ with GalNAc4S6S:GalNAc4S in a ratio of 1.5:1, and three types of sulfated fucosyl branches attaching C-3 of GlcA, namely, Fucp2S4S, Fucp3S4S, and Fucp4S, were found in a ratio of 2:1.5:1. The digestibility of FCSSJ was investigated in vitro, and the unchanged molecular weight and reducing sugar content indicated that FCSSJ was not broken down under salivary and gastrointestinal digestion. Furthermore, FCSSJ showed a significant inhibitory impact on pancreatic lipase dose-dependently but not on α-amylase, indicating that the inhibition of pancreatic lipase by FCSSJ might be a pathway for its hypolipidemic effect. These findings propose a fucosylated chondroitin sulfate and provide insight into the mechanism of its physiological effects in the digestion system.