Sachiko Tsukamoto

Studies on the constituents of asclepiadaceae plant—LVII: The structures of six glycosides, wilfoside c1n, c2n, c3n, c1g, c2g and c3g, with novel sugar chain containing a pair of optically isomeric sugars

Abstract Six new glycosides named wilfoside C3N ( l ), C1N ( 2 ), C2N ( 3 ), C3G ( 4 ), C1G ( 5 ) and C2G ( 6 ) were isolated from Cynanchum wilfordi hemsley (Asclepiadaceae) and their structures were deduced on the basis of the chemical and spectral evidence. It is quite unusual that 2 , 3 , 5 and 6 include both D-cymarose and L-cymarose in each sugar chain.

THREE NEW OXYLIPINS RELATED TO 3,6-DIOXO-4-DOCOSENOIC ACID FROM OKINAWAN MARINE SPONGES, PLAKORTIS SPP.

Abstract Manzamenones J ( 1 ) and K ( 2 ) and plakoridine B ( 3 ), three new oxylipins with unique carbon-skeletons related to 3,6-dioxo-4-docosenoic acid, were isolated from Okinawan marine sponges, Plakortis spp., and their structures elucidated on the basis of spectral and chemical means. Absolute stereochemisty of manzamenone A ( 4 ) was investigated by appling the modified Moshers method developed recently for secondary carboxylic acids by Kusumi.

Pregnane glycosides from Boucerosia aucheriana

Abstract Ten glycosides named bouceroside-ANC, -ADC, -ANO, -ADO, -BNO, -BDO, -BNC, -BDC, -CNO and -CNC were isolated from Boucerosia aucheriana and their structures deduced on the basis of the chemical and spectral evidence. The absolute configuration of cymarose, which was obtained by acidic hydrolyses of seven of the glycosides, was determined by means of HPLC analysis of its carbamoyl derivative on a chiral column as d cymarose.

Manzamenones G and H, new dimeric fatty-acid derivatives from the Okinawan marine sponge Plakortis sp.

Abstract Manzamenone G (1), a novel dimeric fatty-acid derivative with a new carbon-skeleton, was isolated from the Okinawan marine sponge Plakortis sp. together with manzamenone H (2), a new tyramine-containing manzamenone congener, and their structures elucidated on the basis of spectral and chemical means.

New congeners of swinholides from the okinawan marine sponge Theonella sp.

Four new cytotoxic dimeric macrolides, swinholides D–G and a monomeric seco acid of swinholide A have been isolated from the Okinawan marine sponge Theonella sp. together with known macrodiolides, swinholides A and B and isoswinholide A and the structures elucidated on the basis of spectroscopic data.

New congeners of bistheonellides from Okinawan marine sponges of the genus Theonella

Four new bistheonellide-related compounds, bistheonellide C, isobistheonellide A and bistheonellic acids A and B, have been isolated from Okinawan marine sponges of the genus Theonella, and their structures elucidated by spectral and chemical means.

A novel disaccharide, wilforibiose from cynanchum wilfordi h(=emsl)

Abstract The structure of a novel disaccharide, wilforibiose, isolated from the root of Cynanchum wilfordi H(=emsl), has been established by spectral data.

Studies on the constituents of Asclepiadaceae plants. Part 67. Further studies on glycosides with a novel sugar chain containing a pair of optically isomeric sugars, D- and L-cymarose, from Cynanchum africanum

Two new glycosides named cynafoside-C (3) and -D (4) were isolated from Cynanchum africanum R. BR. (Asclepiadaceae), and their structures were deduced on the basis of spectral and chemical evidence. The absolute configurations of cymarose, oleandrose, and digitoxose included in compounds (3) and (4) were each determined by h.p.l.c. analysis of their carbamoyl derivatives on a chiral column after acidic hydrolysis of the glycosides. A unique feature is that cynafoside-C (3), as well as cynafoside-A (1) and B (2), contains a pair of optically isomeric sugars, D-and L-cymarose, in the sugar chain.

Identification of the absolute stereochemistry of D- and L-oleandroses using a chiral h.p.l.c. column

The absolute stereochemistry of D- and L-oleandroses has been determined for the carbamoyl derivatives of the methyl glycosides by h.p.l.c. using a chiral column. The anomeric stereochemistry of methyl α- and β-oleandrofuranosides has also been studied on the basis of nuclear Overhauser effect (n.O.e.) experiments.

Identification of the absolute stereochemistry of D- and L-digitoxose using a chiral high-pressure liquid chromatography column

The absolute stereochemistry of D- and L-digitoxose was determined by h.p.l.c., on a chiral column, of the 1-O-(3,5-dinitrophenylcarbamoyl)-3,4-O-isopropylidene-α-D- and -L-digitoxopyranose.