The astragalus root is the part that contains the important saponin constituents. These saponins have diuretic, anti-inflammatory, and antihypertensive effects. Because of the various elements contained in the plant (amino acids, coumarins, flavonoids, isoflavonoids, polysaccharides, and trace minerals), it is still unclear which agents are involved in which effects. Saponins are also well-known for their ability to lower cholesterol and enhance the immune system.
Many different subclasses of flavonoids have been described from the genus Astragalus including flavones, flavonols, flavanones, flavanonols, chalcones, aurones, isoflavones, isoflavones, and pterocarpans. The number of flavones from the genus according to our literature survey is 22. Flavonols are the most frequently isolated compounds. Among them, quercetin, kaempferol, and their glycosides were found in a higher number of Astragalus species. Flavonoids provide health benefits through cell signaling. They demonstrate antioxidative qualities, control and scavenge free radicals, and can help prevent heart disease, cancer, and immunodeficiency viruses.
Recently, a great deal of interest has been developed to isolate and investigate novel bioactive components with health benefit effects from natural resources. The dried root of Astragalus membranaceus, one of the most popular health-promoting herbal medicines, has been used historically as an immune-modulating agent for the treatment of the common cold, diarrhea, fatigue, and anorexia for more than 2000 years. Modern phytochemistry and pharmacological experiments have proven that polysaccharide is one of the major active ingredients in the root of A. membranaceus with various important bioactivities, such as immunomodulation, antioxidant, antitumor, anti-diabetes, antiviral, hepatoprotection, anti-inflammation, anti-atherosclerosis, hematopoiesis, and neuroprotection.