Characterization and biological activities of a high-yield galactosylated heparan sulfate from Bursatella leachii egg strings.

Systematic analysis of the gelatinoid of the sea hare Bursatella leachii egg strings showed that the material almost entirely consisted of polysaccharides. Hot water treatment could efficiently and conveniently extract the acidic polysaccharides (BLP) almost completely, with a yield of up to 50 % of the dry weight of the egg strings. Physicochemical analysis revealed that BLP is composed of glucuronic acid, glucosamine, galactose, and sulfate groups in a molar ratio of 1.00: 1.00: 1.12: 2.40, with a molecular weight of 359.7 kDa. The sulfation degree is comparable to heparin and higher than that of heparan sulfate. NMR analysis revealed that the backbone of BLP was as 4)-D-GlcA(S)-(β1, 4)-D-GlcN (Ac/S3S)-(α1, within the glucosamine residues could be modified by sulfated Gal via an α1, 6-glycosidic bond, representing the first discovery of an HS derivative with extensive Gal side-chains. BLP exhibited certain anticoagulant activity and potent heparanase inhibition. It also effectively suppressed the migration and invasion of 4 T1 mammary carcinoma cells, with superior anti-metastatic effects demonstrated by its typical low-molecular-weight product dBLP-5. This study enriches our understanding of natural GAGs and offers a high-yield source for developing potent heparin-like therapeutic compounds.