Laminarin acetyl esters: Synthesis, conformational analysis and anti-viral effects

Chemical modification of polysaccharides is important for expanding their applications and gaining new insights into their structure-property relationships. Here we reported the synthesis, characterization, and anti-viral activities of laminarin acetyl derivatives. The chemical structure and chain conformation of acetylated laminarin were characterized by FT-IR, H¹ NMR, AFM, UV-vis spectrum, and induced circular dichroism based on a modified Congo Red assay (ICD-CR assay). The inhibition effect of laminarin and its acetyl derivatives on HSV-1 was evaluated by viral plaque assay and virus-associated DNA/protein change. Acetylation modification was found to trigger the conformation transition of laminarin from triple helix to single helix, and the extent of transition can be tuned by the degree of substitution. The single helical acetylated laminarins were found to be stable in neutral aqueous solution and exhibited no cytotoxicity. However, the acetylated laminarin exhibited declined antiviral activity after modification.