OBJECTIVETo study the antioxidant activities of different extracts from Astragalus mongholicus.

METHODThe antioxidant activities of the total flavanoids (TFA), the total saponins (TSA) and the total polysaccharides (TPA) from A. mongholicus were measured by means of biochemiluminescence. The concentrations of these samples varied from 1.25 x 10(-3) g x L(-1) to 25 x10(-3) g x L(-1).

RESULTAll the extracts showed antioxidant activities of scavenging 3 different free radicals with obvious concentration-scavenging capacity relationship. The antioxidant activity of TFA was the strongest among them. The IC50 of scavenging superoxide anion radicals of TFA (55.48% TFA, 0.59% TFA and 0.36% TFA) were 0.654 2, 4.654 4 and 6.055 2 g x L(-1), the IC50 of scavenging hydroxyl anion were 0.060 5, 0.254 4 and 0.493 0 g x L(-1), and the IC50 of scavenging hydrogen peroxide were 0.010 4, 0.156 0 and 0.224 0 g x L(-1), respectively.

CONCLUSIONThe extracts are more sensitive to hydrogen peroxide and hydroxyl anion than to superoxide anion radicals. TFA of A. mongholicus Bunge is the main component responsible for antioxidant activity, while TSA and TPA have weaker antioxidant activity. The antioxidant activity of TFA increases with the rise of its purity. On the contrary, the antioxidant activity of TSA and TPA decreases with the rise of their purity.