On the Constituents of Linaria japonica MIQ. I. The Structure of Linarioside, a New Chlorinated Iridoid Glucoside and Identification of Two Related Glucosides

The iridoid glucoside composition of Linaria japonica MIQ., a Japanese folk medicine known as a laxative and diuretic, has been clarified to comprise antirride (Ia), antirrhinoside (IIa) and linarioside (IIIa). Linarioside is a new iridoid glucoside possessing a chlorohydrin moiety and the structure has been established as IIIa on the basis of physicochemical evidences and conversion into the corresponding epoxide antirrhinoside (IIa). Antirrhinoside is the major component of the plant and has been revealed to possess a weak and slow laxative property. In addition, the detailed proton magnetic reronance examinations on these glucosides and their derivatives have been presented.