Antioxidant potential of an extract of Calendula officinalis flowers in vitro and in vivo

An extract of Calendula officinalis Linn. (Compositae) was evaluated for its antioxidant potential in vitro and in vivo. Calendula officinalis extract was found to scavenge superoxide radicals generated by photoreduction of riboflavin and hydroxyl radicals generated by Fenton reaction and inhibited in vitro lipid peroxidation. Concentrations needed for 50% inhibition (IC50) were 500, 480, and 2000 mu g/mL, respectively. Extract scavenged ABTS radicals and DPPH radicals and IC50 were 6.5 and 100 mu g/mL, respectively. IC50 values were compared with that of ginger extract, which is a standard antioxidant extract. The drug also scavenged nitric oxide, and the IC50 was found to be 575 mu g/mL. Extract also produced dose-dependent scavenging of nitric oxide in culture. The oral administration of Calendula extract inhibited superoxide generation in macrophages in vivo by 12.6% and 38.7% at doses of 100 and 250 mg/kg b.wt. Oral administration of Calendula officinalis to mice for 1 month significantly increased catalase activity. The extract produced significant increase in glutathione levels in blood and liver. Glutathione reductase was found to be increased, whereas glutathione peroxidase was found to be decreased after administration of Calendula extract. These results indicated Calendula officinalis has significant antioxidant activity in vitro and in vivo.