Influence of extraction conditions on antioxidant activities and catechin content from bark of Ulmus pumila L

This study investigated the influence of extraction conditions on antioxidant activities and catechin content from bark of Ulmus pumila . The U. pumila was extracted using various concentrations of ethanol (30, 50, 80, and 99 %) and different extraction times (1, 2, and 3 h) at 60 °C. The ethanol extracts were evaluated for their antioxidant activities [1,1-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activities and reducing power], total phenolic (TP), and proanthocyanidin (TA) contents. In addition, the antioxidant activities were correlated with TP and TA contents, and the catechin content was determined using high-performance liquid chromatography. The 99 % EtOH for 3-h extracts exhibited the highest antioxidant abilities with the highest phenolic and proanthocyanidin contents. TP content showed little correlation ( R 2 = 0.31–0.61) with their antioxidant activities; however, a significant correlation ( R 2 = 0.65–0.91) was observed with proanthocyanidin content. The catechin content of the 99 % EtOH for 3-h extracts was greater than that of other EtOH extracts. Therefore, these results indicate that the antioxidant capacity of EtOH extracts from bark of U. pumila may be due to catechin, and the optimal extraction condition was 99 % EtOH for 3 h.