Identification of immunostimulants derived from the plant Astragalus membranaceaus

Abstract

As one or the body's primary defense mechanisms, the immune system has developed the capacity to detect, analyze, record and attach a wide variety of externally introduced invasive organisms as well as defective host tissues. This gives the immune system the ability to react to a seemingly unlimited number of foreign agents. Within this body of agents exists a relatively new group of compounds known as immunostimulants. Immunostimulant refers to several classes of compounds chat enhance the response of the various branches of the immune system. In an effort to investigate the use of the Chinese herbal plant Astragalus membranaceaus as a medicinal drug, it was found that some of the plant extracts had immunostimulatory activity. From these extracts, three branched polysaccharides (Mol. Wt= 5.20*10^5, 3.38*10^4 and 6.00*10^3), were isolated and found to act as immunostimulants. This dissertation describes the isolation and structural analysis of these three polysaccharides.