A heparan-like glycosaminoglycan from the white jade snail: Precise structural elucidation, alkaline-induced...

White jade snail (a bred albino variant of Achatina fulica) is widely used in China as an edible and medicinal resource. Previous studies have reported the overall structural characteristics of its glycosaminoglycan (GAG) at the polymer level; however, precise oligosaccharide evidence and structure-function relationships have remained insufficient. In this study, the heparan-like GAG from farmed white jade snails (AfH) was structurally elucidated using a bottom-up strategy based on well-defined oligosaccharides generated by β-eliminative and deaminative depolymerization, revealing a highly regular disaccharide repeating unit of -[4-D-GlcNAc-α1,4-L-IdoA_2S-α1,]-. Notably, alkaline processing was demonstrated to induce artificial structural alterations, including 2-O-desulfation of IdoA_2S, conversion of IdoA to GalA, and epimerization of GlcNAc to ManNAc. AfH exhibited potent heparanase inhibitory activity while showing negligible anticoagulant and P-selectin inhibition, with activity correlated with molecular weight and sulfate content. Structural variations showed distinct biological impacts. ManNAc introduction in a tetrasaccharide (Tetra-2) enhanced heparanase inhibition. Functionally, AfH significantly suppressed 4T1 cell migration and invasion and reduced pulmonary metastasis in mice. This work establishes AfH as a natural resource abundant, well-defined, non-anticoagulant heparan-like GAG with strong anti-metastatic potential, while highlighting alkaline processing as a critical determinant of GAG structural integrity and bioactivity.