Studies on Monoterpene Glucosides and Related Natural Products. XVII. The Intermediacy of 7-Desoxyloganic Acid and Loganin in the Biosynthesis of Several Iridoid Glucosides

Administration experiments of labelled compounds into several plants revealed that 7-desoxyloganic acid is the intermediate in the biosynthesis of iridoid glucosides such as verbenalin (2), loganin (4), geniposide (5), asperuloside (6), and aucubin (10). Tracer experiments on asperuloside (6) proved that loganin (4) (or loganic acid (3)) locates biosynthetically between 7-desoxyloganic acid (1) and the glucosides formed after geniposide (5).