Astragalus contains three components that allow the plant to have such a positive impact on human health: saponins, flavonoids and polysaccharides. Saponins are known for their ability to lower cholesterol, improve the immune system. Flavanoids, also found in astragalus, provide health benefits through cell signaling. They show antioxidative qualities, control and scavenge of free radicals, and can help prevent heart disease and immunodeficiency viruses. Polysaccharides are known to have antimicrobial, antiviral and anti-inflammatory capabilities, among other health benefits. It is widely used in the fields of medicine and health products and cosmetics.
http://www.naturalinbio.com/organic-plant-extracts/organic-astragalus-extract.html