Takenori Natori

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.

Agelasphins, novel α-galactosylceramides from the marine sponge Agelas mauritianus

Abstract New glycosphingolipids, agelasphins ( 1–4 ), have been isolated from the marine sponge Agelas mauritianus , and their structures were determined. Agelasphins having antitumor activity are the first examples of galactosylceramides containing an α-galactosyl linkage.

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.

Immunostimulatory activities of monoglycosylated α-d-pyranosylceramides

Abstract We compared the immunostimulatory effects of chemically synthesized α-galactosylceramides (α-GalCers), α-glucosylceramides (α-GluCers), 6″-monoglycosylated α-GalCer and 6″- or 4″-monoglycosylated α-GluCer and made the following observations: (1) the length of the fatty acid side chain in the ceramide portions greatly affects the immunostimulatory effects of α-GalCers and α-GluCers; (2) the configuration of the 4″-hydroxyl group of the inner pyranose moiety plays an important role in the immunostimulatory effects of monoglycosylated α- d -pyranosylceramides; (3) the free 4″-hydroxyl group of the inner pyranose of monoglycosylated α- d -pyranosylceramides plays a more important role in their immunostimulatory effects than the free 6″-hydroxyl group.

Immunostimulatory activities of mono- or diglycosylated α-galactosylceramides

Abstract We examined the effects of 2″- or 3″-monoglycosylated α-galactosylceramides (α-GalCers) and 2″,3″-diglycosylated α-GalCers on allogeneic MLR and the proliferation of murine spleen cells. It was found that their ceramide portions greatly affect their immunostimulatory activities, and that the 3″-hydroxyl group plays a more important role in the immunostimulatory effects of α-GalCer derivatives than the 2″-hydroxyl group.

Poecillanosine, a new free radical scavenger from the marine sponge Poecillastra spec. aff. tenuilaminaris

Abstract A new free radical scavenger, poecillanosine ( 1 ) was isolated from the marine sponge Poecillastra spec. aff. tenuilaminaris and its structure elucidated as a nitrosohydroxyalkylamine.