Kohji Akimoto

Agelasphins, novel antitumor and immunostimulatory cerebrosides from the marine sponge Agelas mauritianus

Abstract New glycosphingolipids, named agelasphins ( 1-8 ), have been isolated by antitumor and immunostimulatory bioassay-guided purification from an extract of a marine sponge, Agelas mauritianus . Strongly active agents in agelasphins had characteristic α-galactosylceramide structures, the isolation of which from natural products has not previously been reported. The absolute configurations of agelasphins were elucidated by the total synthesis.

Synthesis and stereochemistry of agelasphin-9b

Abstract Agelasphin-9b, one of the α-galactosylceramides from an Okinawan marine sponge, was synthesized, and the absolute stereochemistry was determined.

Practical Total Synthesis of (2S, 3S, 4R)-1-O-(α-D-Galactopyranosyl)-N-hexacosanoyl-2-amino-1, 3, 4-octadecanetriol, the Antitumorial and Immunostimulatory α-Galactosylcer-amide, KRN7000

A practical total synthesis of (2S,3S,4R)-l-O-(α-d-galactopyranosyl)-N-hexacosanoyl-2-amino-l,3,4-octadecanetriol (KRN7000), an antitumorial and immunostimulatory glycosphingolipid derived from agelasphins, was achieved in 14 steps starting from d-lyxose in a 16% overall yield.

Syntheses of α-, β-monoglycosylceramides and four diastereomers of an α-galactosylceramide

Abstract To examine antitumor activities of monoglycosylceramide, we synthesized α-, β-galactosylceramides and α-, β-glucosylceramides which have the same ceramide portion, and four kinds of diastereomers of the ceramide portion in an α-galactosylceramide.

The total synthesis of (±)-coriolin

Abstract The first total synthesis of (±)-coriolin from the tricyclo 6-4-5 -fused ring photo-adduct through the key tricyclo 5-5-5-fused ring intermediate, 7,8,11 - trihydroxy - 1,4,4 - trimethyltricyclo[6.3.0.0 2,6 ]undecan - 3 - one, is described.

Total synthesis of apramycin

Abstract Apramycin has been stereoselectively synthesized from the previously synthesized aminoglycoside antibiotic, neamine, through the aminooctodiose derivative, aprosamine.

Radioprotective effects of α-galactosylceramides

Abstract We examined the life-span-prolonging effects of five kinds of α-Galactosylceramides (α-GalCers) on mice irradiated with lethal dose (9 Gy) of X ray, and found that they show strong radioprotective activities even when they are administered to mice after the irradiation. These results suggest that α-GalCers are useful as radioprotective agents.

Effects of 3α- and 3β-galactosylated α-g galactosylceramides on the immune system

We compared effects of alpha-galactosylceramide (alpha-GalCer) and its 3alpha- or 3beta-galactosylated derivatives on the proliferation of murine spleen cells. The 3alpha-galactosylated alpha-GalCer showed stronger proliferative response than the parental alpha-GalCer, but the 3beta-galactosylated alpha-GalCer possessed weaker activity than the alpha-GalCer. In addition, alpha-Gal-3-Cer did not show immunostimulatory activity.