Effects of alkali dissociation on the molecular conformation and immunomodulatory activity of longan pulp polysaccharide (LPI)

► Longan polysaccharide (LPI) has been confirmed with sphere-like conformation. ► The sphere-like conformation can be dissociated by alkali solution. ► The immunomodulatory activity of LPI can be enhanced by alkali dissociation. ► Single-helix chain may play an important role in activating lymphocytes and NK cells, but having weak contribution to macrophage phagocytosis.