In vitro and vivo antioxidant activities of daylily flowers and the involvement of phenolic compounds.

Daylily (Hemerocallis fulva Linn.) flowers were hot air-dried and freeze-dried after harvest. Antioxidant properties of water and ethanol extracts prepared from these dried flowers were evaluated in terms of total antioxidant activity, reducing capacity, and metal chelating activity. Extracts from daylily flowers exhibited strong antioxidant activity. Ethanol was more efficiency to extract antioxidants than water, and freeze-drying preserved higher activities than air-drying. Rutin, (+)-catechin, and gallic acid were identified in the extracts by HPLC, and were highly related to the antioxidant activities. The antioxidant activity was further evaluated by feeding mice with ethanol extract from freeze-dried daylily flowers for 60 days. The results demonstrated that the extract at dosage of 40-225 mg/100 g significantly increased the activity of SOD (superoxide dismutase) and reduced the lipid peroxidation in both blood and liver of rat.