Antioxidant Activities and Xanthine Oxidase Inhibitory Effects of Extracts and Main Polyphenolic Compounds Obtained from Geranium sibiricum L.

The antioxidant capacity and xanthine oxidase inhibitory effects of extracts and main polyphenolic compounds of Geranium sibiricum were studied in the present work. The antioxidant capacity was evaluated by ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, superoxide radical scavenging, nitric oxide scavenging, β-carotene−linoleic acid bleaching, and reducing power assays. Among the extracts and four fractions, the ethyl acetate fraction showed the highest phenolic content (425.36 ± 9.70 mg of gallic acid equivalent/g extracts) and the best antioxidant activity. The IC50 values of the ethyl acetate fraction were 0.93, 3.32, 2.06, 2.66, and 1.64 μg/mL in the DPPH radical scavenging, superoxide radical scavenging, nitric oxide scavenging, β-carotene−linoleic acid bleaching, and reducing power assays, respectively. Of the polyphenolic compounds separated from the ethyl acetate fraction, geraniin showed a higher activity than corilagin and gallic acid. The IC50 values...