Antioxidative activities of ethanolic extracts of Du-zhong (Eucommia ulmoidesOliver) leaf and bark

Antioxidative activities of 50% ethanolic extracts from Du-zhong (Eucommia ulmoides Oliver) leaf and bark were investigated. Yields of the leaf and bark extract were 8.1±0.31 and 17.4±0.89%, respectively. Polyphenol contents of the leaf and bark extract were 64.1±3.35 and 42.4±2.38 μg gallic acid equivalents/ mg, respectively. Flavonoid contents of the leaf and bark extract were 24.0±3.15 and 36.7±3.18 μg quercetin equivalents/mg, respectively. As concentration of the leaf and bark extract increased, their antioxidative activities proportionally increased. EC50 values of the leaf and bark extract for cation radical scavenging were 560.6±17.65 and 1,357.4±8.45 μg/mL, respectively. EC50 values of the leaf and bark extract for free radical scavenging were 574.2±14.70 and 2,103.1±108.59 μg/mL, respectively. EC50 values of the leaf and bark extract for ferric reducing antioxidant power were 319.9±13.42 and 705.9±26.08 μg/mL, respectively. EC50 values of the leaf and bark extract for nitrite scavenging were 2,329.2±35.11 and 5,467.6±243.92 μg/mL, respectively. In the presence of 74.8 μg/mL of the leaf extract and 177.2 μg/mL of the bark extract, linoleic acid peroxidation was inhibited by 70.0 and 79.1%, respectively. The Du-zhong leaf extract possessed higher antioxidative activities than its bark extract.