[Graded ethanol precipitation method on physicochemical properties and antioxidant activities of polysaccharides extracted from Astragalus Radix].

Astragalus polysaccharide has been widely used in food and medicinal industry owing to its health-promoting properties. In order to characterize better the relationship among molecular weight, structure-activity and activities, a simple method was used different concentration of ethanol including 30% (PW30), 50% (PW50), 70% (PW70), 75% (PW75), 80% (PW80) and 90% (PW90) to precipitate Astragalus polysaccharides into different molecular weight. As a result, PW90 showed smooth surface and the strongest antioxidant activity among these six fractions (P < 0.05). In conclusion, graded ethanol precipitation was a simple method to separate Astragalus polysaccharides into different molecular weight with different antioxidant activity fractions.