Wittiorumins A - F, antioxidant diels-alder-type adducts from Morus wittiorum.

Six new Diels-Alder-type adducts, wittiorumins A-F ( 1 - 6) along with the three known compounds chalcomoracin ( 7), mulberrofuran J ( 8), and mongolicin F ( 9), were isolated from the stem bark of Morus wittiorum. Their structures including their absolute configurations were determined on the basis of spectroscopic analysis and chemical methods. Some of the isolated compounds ( 1 - 4) were assayed for their antioxidant activities, among which compounds 1 - 3 were active as antioxidants, with inhibitory ratios of 73.0 %, 82.0 %, and 82.0 %, respectively, at a concentration of 10 ( - 5) M.