Biologically active glycosides from asteroidea, 42. Isolation and structure of a new biologically active ganglioside molecular species from the starfish Asterina pectinifera.

A ganglioside molecular species GP-3 (1) has been obtained from the water-soluble lipid fraction of the chloroform/methanol extract of the starfish Asterina pectinifera. The structure of the ganglioside has been determined on the basis of chemical and spectroscopic evidence. Compound 1 represents new ganglioside molecular species possessing two moles of sialic acids at the inner part of the sugar moiety. Partial hydrolysis by hot water and an enzymatic hydrolysis by means of endoglycoceramidase (EGCase) have proved useful for structure elucidation of the complex oligosaccharide moiety. Moreover, 1 exhibits neuritogenic activity toward the rat pheochromocytoma cell line, PC-12 cells, in the presence of nerve growth factor (NGF).

Biologically active glycosides from asteroidea, 43. Isolation and structure of a new neuritogenic-active ganglioside molecular species from the starfish Linckia laevigata.

A ganglioside molecular species, LLG-5 (1), has been obtained from the water soluble lipid fraction of the CHCl3/MeOH extract of the starfish Linckia laevigata. On the basis of chemical and spectroscopic findings, the structure of 1 has been elucidated. Negative ion FAB-MS provided important information both on the structure of the sugar moiety and on the molecular mass of the ganglioside. 1 is a new ganglioside molecular species possessing a 2-->11 linked linear-type trisialosyl moiety. Moreover, 1 exhibited neuritogenic activity in rat pheochromocytoma PC-12 cells in the presence of nerve growth factor.

Constituents of Holothuroidea, 15. Isolation of ante-iso type regio-isomer on long chain base moiety of glucocerebroside from the sea cucumber Holothuria leucospilota.

An ante-iso type regio-isomer on the long chain base moiety of a glucocerebroside, HLC-2-A, has been isolated from its parent glucocerebroside molecular species HLC-2 composed of iso and ante-iso isomers, from the less polar lipid fraction of a chloroform/methanol extract of the sea cucumber Holothuria leucospilota. Reverse-phase HPLC that included a recycling system was effective in separating the regio-isomer from its counterpart, revealing a very close resemblance in structure. Other typical glucocerebroside molecular species HLC-1 and HLC-3 were obtained together with HLC-2. The structures of these glucocerebrosides were determined on the basis of chemical and spectroscopic evidence.

Isolation and structure of a GD3-Type ganglioside molecular species possessing neuritogenic activity from the starfish Luidia maculata.

A GD3-type ganglioside molecular species, LMG-4 (1), has been obtained from the polar lipid fraction of the chloroform/methanol extract of the starfish Luidia maculata. The structure of this ganglioside has been determined on the basis of chemical and spectroscopic evidence to be 1-O-[(N-acetyl-alpha-D-neuraminosyl)-(2-->8)-(N-acetyl-alpha-D-neuraminosyl)-(2-->3)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl]-ceramide. The ceramide moiety was composed of heterogeneous 2-hydroxy fatty acid and phytosphingosine units. This is the first report on the isolation and structure elucidation of GD3-type ganglioside from echinoderms. Moreover, 1 exhibited neuritogenic activity toward the rat pheochromocytoma PC12 cells in the presence of nerve growth factor.

Differentiation of a pair of diastereomeric tertiarybutoxycarbonylprolylproline ethyl esters by collision-induced dissociation of sodium adduct ions in electrospray ionization mass spectrometry and evidence for chiral recognition by ab initio molecular orbital calculations.

The fragmentation of the sodium adduct ions for tert-butoxycarbonyl-L-prolyl-L-proline ethyl ester (Boc-L-Pro-L-Pro-OEt) was compared with that for Boc-D-Pro-L-Pro-OEt in positive-ion electrospray ionization (ESI) mass spectrometry. In the collision-induced dissociation (CID) mass spectra of the [M + Na](+) ions, the abundance of the [M + Na - C(CH(3))(3) + H](+) ion, which is due to the loss of a tert-butyl group from the [M + Na](+) ion for Boc-D-Pro-L-Pro-OEt, was about eight times higher than that for Boc-L-Pro-L-Pro-OEt. In addition, in the CID spectra of the sodium adduct fragment ion ([M + Na - Boc + H](+)), the abundance of the [M + Na - Boc - prolylresidue + H](+) ion, which is due to the loss of prolyl residue from the [M + Na - Boc + H](+) ion for Boc-L-Pro-L-Pro-OEt, was about five times higher than that for Boc-D-Pro-L-Pro-OEt. These results indicate that Boc-L-Pro-L-Pro-OEt was distinguished from Boc-D-Pro-L-Pro-OEt by the CID mass spectra of the sodium adduct ions in ESI mass spectrometry. The optimized geometries of the [M + Na](+) and the [M + Na - Boc + H](+) ions calculated by ab initio molecular orbital calculations suggest that the chiral recognition of these diastereomers was due to the difference of the orientation of a sodium ion to the oxygen and nitrogen atoms in dipeptide derivatives, and to the difference of the total energies between them.

Constituents of holothuroidea, 12. Isolation and structure of glucocerebrosides from the sea cucumber Holothuria pervicax.

Ten glucocerebrosides, HPC-3-A-HPC-3-J, have been isolated from their obtained parent glucocerebroside molecular species HPC-3, together with other glucocerebroside molecular species HPC-1 and HPC-2, from the less polar lipid fraction of a chloroform/methanol extract of the sea cucumber Holothuria pervicax. The structures of these glucocerebrosides have been determined on the basis of chemical and spectroscopic evidence. Reversed-phase HPLC, including a recycling system, was effective in isolating these glucocerebrosides, revealing a very close resemblance in structure, though the problem due to regio-isomers remains.

Isolation and structure of monomethylated GM3-type ganglioside molecular species from the starfish Luidia maculata.

Two monomethylated GM(3)-Type ganglioside molecular species, 1 and 2, have been obtained from the polar lipid fraction of the chloroform/methanol extract of the starfish Luidia maculata. The structures of these gangliosides have been determined on the basis of chemical and spectroscopic evidence as 1-O-[8-O-methyl-(N-acetyl-alpha-D-neuraminosyl)-(2-->3)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl]-ceramide (1) and 1-O-[8-O-methyl-(N-glycolyl-alpha-D-neuraminosyl)-(2-->3)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl]-ceramide (2). The ceramide moieties were composed of heterogeneous unsubstituted fatty acid, 2-hydroxy fatty acid, sphingosine and phytosphingosine units. Compound 1, designated as LMG-3, represents new ganglioside molecular species. Compound 2 was a known ganglioside molecular species.