Antioxidant activities of ethanolic extract and lyoniresinol from bark of Zelkova serrata.

Reactive oxygen species- (ROS) induced oxidation stress is a key cause of human health problems. Studies have shown that many diseases, such as Alzheimer's disease, Parkinson's disease, diabetes, carcinogenesis and inflammatory diseases, are associated with ROS. Plant polyphenols have the ability to remove these ROS in the human body, indicating their potential to improve human health. Zelkova serrata is a traditional medicinal plant in Taiwan and all of its plant parts have various health applications and even antioxidant activities. This study aimed to understand the antioxidant activities of bark polyphenols from Z. serrata and their active components. Results showed that the ethanolic extract of bark had free-radical scavenging abilities and reducing power. Although the extract barely had any flavonoids or condensed tannins, it comprised polar polyphenols with antioxidant activities. Furthermore, antioxidant activities in the extract originated mainly from lyoniresinol via hydrogen atom and electron transfer. These findings suggest that the bark extract of Z. serrata is also a potential resource for health improvement. [ABSTRACT FROM AUTHOR]