Total Phenols, Flavonoid Contents, and Antioxidant Activity of Spirodela polyrhiza Extracts

We investigated the antioxidant activities of water and ethanol extracts from Spirodela polyrhiza (SP) through in vitro assays. The total phenolic contents of SP water and ethanol extracts were 52.75-293.4 and 60.12-398.4 mg/g, respectively. The total flavonoid content of SP ethanol extract (38.25-159.4 mg/g) was higher than that of SP water extract (38.25-67.75 mg/g). The water and ethanol extracts from SP scavenged the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2-azino-di-2-ethyl-benzothia-zoline sulfonate (ABTS) radical in a dose-dependent manner in the concentration range of 100–2,500 μg/ml. The DPPH radical scavenging activity of the SP ethanol extract (2.87%-59.5%) was higher than that of the water extract (4.12%-81.52%). The IC 50 s of the DPPH radical scavenging activity of water and ethanol extracts were 2,100 and 1,034 μg/ml respectively. The ABTS radical scavenging activities of SP water and ethanol extracts were 8.30%-83.16% and 13.11%-8.34% respectively. The IC 50 s of the ABTS radical scavenging activity of SP water and ethanol extracts were 798.7 and 457.1 μg/ml, respectively. The reducing power activities of SP water and ethanol extracts were 0.055-1.122 and 0.140-1.428, respectively (500-4,000 μg/ml). The soybean lipoxygenase (SLO) radical scavenging activities of SP water and ethanol extracts were 157.7%-168.0% and 148.0%-169.4%, respectively. These results suggest that the water and ethanol extracts of SP may be useful as a potential antioxidant.