Antioxidant properties of different molecular weight polysaccharides from Athyrium multidentatum (Doll.) Ching

• Polysaccharides from Athyrium multidentatum (Doll.) Ching were degraded into four low molecular polysaccharides.
• The antioxidant activities of the low molecular polysaccharides were investigated.
• The effect of molecular weight on antioxidant ability was significant and complicated.

Different molecular weight polysaccharides were prepared by degradation of polysaccharides extracted from Athyrium multidentatum (Doll.) Ching rhizome (CPA) with hydrogen peroxide and ascorbic acid. Four low molecular polysaccharides derivatives (CPA-1, CPA-2, CPA-3 and CPA-4) were successfully obtained and had their antioxidant activities investigated employing various established in vitro systems. All CPA derivatives showed pronounced antioxidant activity, and had stronger antioxidant ability than CPA in certain tests. CPA-1 exhibited the strongest scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical among all samples, and the IC50 value was 25 μg/mL. CPA-2 possessed the highest scavenging ability against superoxide radical at 200 μg/mL. The scavenging activity of CPA-4 on hydroxyl radical was higher than CPA from 120 to 200 μg/mL. The mechanism on influence the antioxidant activity of CPA and its degraded derivatives was indicated.