Kiyokazu Takaishi

A secoiridoid glucoside from Olea europaea

Abstract Besides two known glucosides, olcuropein and ligstroside, a new secoiridoid glucoside, oleuroside was isolated from Olea europaea and its structure

A quinol glucoside from Abeliophyllum distichum

Abstract Besides the known glucosides, calceolarioside D, verbascoside, cornoside, rutin and a cyclohexanone derivative, halleridone, a new quinol glucoside, ne

A secoiridoid glucoside from Ligustrum japonicum

Abstract Besides several secoiridoid glucosides including 8-epikingiside, a new secoiridoid glucoside, methyl glucooleoside, was isolated from the ripe berries of Ligustrum japonicum and its structure elucidated.

Intermediacy of 6-hydroxyloganin in the ring cleavage course of loganin to secologanin

Abstract 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 6-hydroxy [7- 2 H] loganin as well as [6,6,7,8- 2 H 4 ] - and [6,6,7,8 carbomethoxy- 2 H 7 ]-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.

A secoiridoid glucoside from Fraxinus insularis

Abstract A new secoiridoid glucoside, insularoside, was isolated from Fraxinus insularis . The structural elucidation of insularoside by spectroscopic and chemical studies is described. The biogenesis of this glucoside is also briefly discussed.

The content of coumarin analogues in red leaves of higher plants

Abstract A remarkable amount of bound o -coumaric acid accompanied by a small amount of coumarin was isolated from red leaves of 20 plant species. It is noteworthy that the leaves of deeper red colour contain a higher amount of the bound o -coumaric acid. The amount of o -coumaric acid in one species reaches a maximum at the beginning of the red colouring, and decreases somewhat as the red colour deepens. This phenomena is interesting from biosynthetical point of view, since it has been shown that both coumarin and anthocyanins are synthesized through shikimic acid pathway. 1