Synthesis of oligosaccharide fragments related to galactomannan from Antrodia cinnamomea and their immunostimulatory activity

This study reports the chemical synthesis of a series of structurally defined oligosaccharide derivatives related to the galactomannan polysaccharide of Antrodia cinnamomea, employing a stepwise glycosylation strategy. Structure-immunostimulatory activity relationship studies demonstrated that, within this series of precisely designed and synthesized compounds, those incorporating a continuous trimannose epitope—such as tetrasaccharides 2a, 2b, 2e and trimannoside 3c—exhibited significant proliferative activity against both the murine monocytic macrophage leukemia RAW264.7 cell and the human monocytic leukemia THP-1 cell. These findings elucidate the structural basis of the active core fragment of A. cinnamomea galactomannan polysaccharide and provide a molecular foundation for the rational design and development of novel immunomodulatory agents.