Taeko Yasuhara

A galloylated monoterpene glucoside and a dimeric hydrolysable tannin from Cornus officinalis

Abstract Two new compounds named cornuside and cornusiin G were isolated from fruits of Cornus officinalis . Their structures were respectively determined to be 7- O - galloylsecologanol and a dimeric hydrolysable tannin composed of tellimagrandin II and 1,2,3,6-tetra- O -galloyl-β- d -glucose.

Oenothein B, a dimeric, hydrolysable tannin with macrocyclic structure, and accompanying tannins from Oenothera erythrosepala

A new dimeric, hydrolysable tannin which we have named oenothein B (1), and eight accompanying compounds, including oenothein C (2), were isolated from the leaves of Oenothera erythrosepala. The macrocyclic structure of compound (1) was established from chemical and spectroscopic data. The previously assigned structure of compound (2) was also confirmed by two-dimensional NMR spectroscopy.

Structure of isorugosin B, and the orientation of valoneoyl group in the related monomeric, dimeric and trimeric hydrolyzable tannins

A new hydrolyzable tannin, named isorugosin B, was isolated from Liquidambar formosana, and the structure in which the orientation of valoneoyl group of the glucose core is the reverse of that in rugosin B and in rugosin A, was determined. The orientation of valoneoyl group in rugosin A was established by the long range 1 H- 13 C correlation nmr spectroscopy

Hydrolyzable tannins having a depsidone-forming valoneoyl group

The orientation of the valoneoyl group in praecoxins C and D as in the structures of praecoxins C and D was unequivocally proved by the 1 H- 13 C long-range shift correlation spectrum of rugosin C which was chemically correlated with praecoxin C