Antioxidant activity of Astragalus polysaccharides and antitumour activity of the polysaccharides and siRNA

In this study, Astragalus polysaccharides was analysed using high performance liquid chromatography (HPLC) and Fourier transform infrared (FT-IR). Compared with retention time of six standard compounds in HPLC analyses, we found that the polysaccharides were composed of glucose. The absorption bands at 1639 and 1538 cm−1 were attributed to the stretching vibration of the C–O bond of carboxyl group. The absorption bands at 1035 and 956 cm−1 suggested that the extract contained pyrene monomer in its structure. The antioxidant activity of Astragalus polysaccharides was evaluated by various antioxidant assays. Astragalus polysaccharides showed strong antioxidant activity in all the tested methods. The in vitro antioxidant capacity of Astragalus polysaccharides was significantly correlated with its content. In addition to the antioxidant activity of the polysaccharides, it still showed strong antitumour activity. Then, CD40 gene siRNA plasmid (Psilencer1. 0-U6-P I3K-siRNA) was constructed. Antitumour activity of siRNA was evaluated. Among these samples, Astragalus polysaccharides exhibited more antitumour potency than siRNA. Mechanism of antitumour activity of Astragalus polysaccharides and siRNA may be explained by decreasing CD40 in cells.