Antioxidant Properties of Extracts from Curcuma zedoaria Rhizome

Abstract

Curcuma zedoaria (Berg.) Rosc. (Zingiberaceae) has long been used as a folk medicine. Volatile compounds were extracted from the rhizome using supercritical carbon dioxide at 10 MPa and 45oC. Totally, 31 compounds, including 15 terpenes, nine alcohols, six ketones and one other compound, were identified. Aqueous and methanolic extracts were prepared from dried rhizome and the methanolic fractions were prepared using silica gel column chromatography. Aqueous and methanolic extracts were extremely effective in antioxidant activity by the 1,3-diethyl-2-thiobarbituric acid method and EC50 (effective concentration at 50%) values of <10 μg/mL. EC50 values of aqueous methanolic and supercritical carbon dioxide extracts in antioxidant activities by the thiobarbituric acid-reactive substances and conjugated diene methods were 6.58-8.86 and 0.43-0.67 mg/mL, respectively. The methanolic extract was more effective in reducing power, scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating ability on ferrous ions. Based on the results obtained, all extracts showed effective antioxidant properties.