Reactive oxygen radicals (ROS) are highly reactive and the overproduction of ROS could induce the pathogenesis of endothelial dysfunction, and might serve as a main cause of the life style diseases, such as hypercholesterolemia, hypertension, atherosclerosis, diabetes mellitus, and several cancers. These life style diseases are currently called as metabolic syndromes. The plant polyphenols as ROS scavengers have been widely studied and dietary antioxidants like tea and wine are well known as antioxidant foods. In order to look for the effective natural antioxidants which possess a health‐benefit function, we have collected and assayed numerous medicinal herbs and plant materials like agricultural by‐products. Some strong antioxidant polyphenols which had been isolated and identified from these plants extracts are presented here.

• Shin‐Kyo Chung(Faculty of Life and Food Sciences, Kyungpook National University)
• Yoshiaki Takaya(Faculty of Pharmacy, Meijo University)
• Niwa Masatake(Faculty of Pharmacy, Meijo University)