INTERMEDIACY OF 6-HYDROXYLOGANIN IN THE RING CLEAVAGE COURSE OF LOGANIN TO SECOLOGANIN

Article abstract of DOI:10.1016/0031-9422(89)80263-8

A possible biosynthetic pathway from loganin to secologanin through ring cleavage of 6-hydroxyloganin was ruled out in feeding experiments in which Eustoma russellianum, Swertia japonica, Lonicera morrowii and Adina pilulifera were each presented with three C-6 and C-7 stereoisomers of hydroxy <7-2H>-loganin as well as <6,6,7,8-2H4>- and <6,6,7,8-carbomethoxy-2H7>-loganin.In an associated experiment, the reduction of the aldehyde group of secologanin leading to sweroside was shown to proceed by hydride ion attack from the si face.Key Word Index - Biosynthesis; ring cleavage; loganin; 6,7-stereoisomer of 6-hydroxyloganin; secologanin; stereochemical course of the reduction; deuterium labelling.