ISOLATION AND CHARACTERIZATION OF YUNNANEIC ACIDS A-D, 4 NOVEL CAFFEIC ACID METABOLITES FROM SALVIA-YUNNANENSIS

In the course of chemical studies on medicinal plants having uremic to xin-decreasing effects, the novel caffeic acid metabolites yunnaneic a cids A-D were isolated from the roots of Salvia yunnanensis. Yunnaneic acids C and D were found to be caffeic acid trimers having a bicyclo[ 2.2.2]octene skeleton, which is biogenetically formed by a Diels-Alder -type addition between rosmarinic acid and caffeic acid. Yunnaneic aci d A has a dimeric structure composed of yunnaneic acids C and D, which are linked by formation of a spiroacetal ring. Yunnaneic acid B consi sts of two molecules of yunnaneic acid C. The structures of the yunnan eic acids were elucidated on the basis of spectroscopic evidence, and their absolute configurations were established by application of the c ircular dichroic exciton chirality method.