Abstract
Apostichopus japonicus is one of the most economically important species in sea cucumber aquaculture in China. Fucosylated glycosaminoglycan from A. japonicus (AjFG) has shown multiple pharmacological activities. However, results from studies on the structure of AjFG are still controversial. In this study, the deaminative depolymerization method that is glycosidic bond-selective was used to prepare the depolymerized products from AjFG (dAjFG), and then a series of purified oligosaccharide fragments such as tri-, hexa-, nona-, and dodecasaccharides were obtained from dAjFG by gel permeation chromatography. The 1D/2D NMR and ESI-MS spectrometry analyses showed that these oligosaccharides had the structural formula of l-FucS-α1,3-d-GlcA-β1,3-{d-GalNAc4S6S-β1,4-[l-FucS-α1,3-]d-GlcA-β1,3-}n-d-anTal-diol4S6S (n = 0, 1, 2, 3; FucS represents Fuc2S4S, Fuc3S4S, or Fuc4S). Thus, the unambiguous structure of native AjFG can be rationally deduced: it had the backbone of {-4-d-GlcA-β1,3-d-GalNAc4S6S-β1-}n, which is similar to chondroitin sulfate E, and each d-GlcA residue in the backbone was branched with a l-FucS monosaccharide at O-3. Bioactivity assays confirmed that dAjFG and nonasaccharides and dodecasaccharides from AjFG had potent anticoagulant activity by intrinsic FXase inhibition while avoiding side effects such as FXII activation and platelet aggregation.
Highlights
Sea cucumber Apostichopus japonicus is widely distributed in the northwestPacific, e.g., northern coast of China and almost all coastal areas of Japan, and has become one of the most popular sea cucumber species around the world due to its high value as a marine tonic [1].Studies on this marine animal showed that it contains valuable nutrients, such as collagens, peptides, amino acids, sphingolipids, and polysaccharides [2]
Enzymatic digestion combined with alkali treatment used in this study is a common method for extracting Fucosylated glycosaminoglycan (FG), which is consistent with the extraction method used for isolation of AjFG by other for extracting FG, which is consistent with the extraction method used for isolation of AjFG by other groups [6,7,21]
Tri, hexa, nona, and dodecasaccharides from AjFG were prepared by the partial deacetylation–deaminative cleavage method combined with the gel chromatography, and their structures were established by NMR and ESI-Q-TOF-MS spectrometry
Summary
Sea cucumber Apostichopus japonicus (or Stichopus japonicus) is widely distributed in the northwest. E.g., northern coast of China and almost all coastal areas of Japan, and has become one of the most popular sea cucumber species around the world due to its high value as a marine tonic [1] Studies on this marine animal showed that it contains valuable nutrients, such as collagens, peptides, amino acids, sphingolipids, and polysaccharides [2]. The oligosaccharides with various degree of polymerization (dp) separated from dAjFG were analyzed by 1D/2D NMR (1 H, 13 C, COSY, TOCSY, ROESY, HSQC, and HMBC) and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-Tof-MS) spectrometry Based on this “bottom-up” strategy, the precise structure of AjFG can be determined reliably.
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