2004 Volume 21 Issue 2 Pages 67-80
The polysaccharide (PS) fractions isolated from fungi and higher plants have been shown as potent biological response modifiers exhibiting immunostimulating and antitumor activities through the functions involving activation of macrophages, cell-mediated immunity and cytokine induction. The primary structure of these PSs exhibits β(1->3), β(1->4)-linkage glycan as the common form of main chain, while the side chains involve β(1->3), β(1->4), β(1->6) or α(1->4) linkages. The hydrogen bond, tertiary structure of triple helix, and high molecular weight contribute to the stability and biological activities of the PSs. The degree of substitution on the backbone chain and the length of the side chains are important for the conformation of structure and their immunologic activity. Here we review the biochemical characterization, immunomodulating activities, and clinical application of important PSs isolated from fungi including Lentinus, Ganoderma, Hoelen, Polyporus, and Ascomyces and higher plants such as Radix Astragali, Angelica, Ginseng, and others. Immunomodulating PSs thus far have been used to prevent disease and promote restoration of the body's homeostasis, and current evaluations focus on treatment of pathogenic factors. Development of these polysaccharides into drugs for therapeutic use needs research on structure-activity relationship and quality assurance for polysaccharide molecules and final products.
