[Studies on caffeic acid derivatives in medicinal plants]

The components of Artemisia and Labiatae species were isolated and their chemical structures were determined. These compounds were found to have tannic activity for the first time. The activity of the compounds comes from the caffeic acid moiety in their molecules, not from structural features of usual tannins (hydrolyzable and condensed tannins). These also showed several other biological activities. Furthermore, the research on dimerization of caffeic acid derivatives was performed.