Constituents of holothuroidea, 16. Determination of Absolute configuration of the branched methyl group in ante-iso type side chain moiety on long chain base of glucocerebroside from the sea cucumber Holothuria leucospilota

The absolute configuration of the branched methyl group in ante-iso type side chain moiety on the long chain base of glucocerebroside, HLC-2-A, which was isolated from the sea cucumber Holothuria leucospilota was determined. Oxidation of the glucocerebroside with ozone afforded C13-fragment including the ante-iso moiety. The optically active C13-fragment was synthesized asymmetrically by using the Wittig reaction from chiral synton for comparison with the natural fragment.     

Blow-up behavior for a nonlinear heat equation with a localized source in a ball

In this paper, we consider the initial-boundary value problem of a semilinear parabolic equation with local and non-local (localized) reactions in a ball: u_t=Δu+u^p+u^q(x^*,t) in B(R) where p,q>0,B(R)={x∈R^N:|x|<R} and x^*≠0. If max(p,q)>1, there exist blow-up solutions of this problem for large initial data. We treat the radially symmetric and one peak non-negative solution of this problem. We give the complete classification of total blow-up phenomena and single point blow-up phenomena according to p and q.

(i)

If or p=q>2, then single point blow-up occurs whenever solutions blow up.

(ii)

If 1<p<q, both phenomena, total blow-up and single point blow-up, occur depending on the initial data.

(iii)

If p?1<q, total blow-up occurs whenever solutions blow up.

(iv)

If max(p,q)?1, every solution exists globally in time.

     

Amphimelibiosides A-F, six new ceramide dihexosides isolated from a Japanese marine sponge Amphimedon sp

Six new ceramide dihexosides, amphimelibiosides A-F (1-6), were isolated from a Japanese marine sponge Amphimedon sp. The structure of amphimelibioside C (3), which is a major component of amphimelibiosides, was determined by 2D NMR techniques, chemical degradation, and a semisynthetic method to be 1-O-[beta-D-glucopyranosyl-(1-->6)-alpha-D-galactopyranosyl]-(2S,3S,4R,6E)-2-[(2'R)-2-hydroxydocosanoyl]-2-amino-6-octadecene-1,3,4-triol. The structures of the other constituents were elucidated by a combination of mass spectra, (1)H NMR, and GC-MS analysis.     

Synthesis of alkylaminoethanethiolsulfuric acids substituted with heterocyclic moieties

Several alkylaminoethanethiolsulfurie acids substituted with heterocyclic moieties have been synthesized to determine their effectiveness as radiation protection agents. These compounds are represented by the structure R(CH₂)₃NH(CH₂)₂S₂O₃H, where R is 8-quinoly-oxy (V), 8-quinaldyloxy (IX), 5-quinolyloxy (XII), 4-pyridyl (XVI), and 4-pyridylmethyl (XXIII). The diheterocyclic-substituted compound, 2-[bis-(2-phenyl-1, 2, 3, 2H-triazol-4-ylmethyl)amino]ethanethiolsulfuric acid (XIV) was also synthesized.     

1,3-dimethylisoguaninium,an antiangiogenic purine analog from the sponge Amphimedon paraviridis

An antiangiogenic purine analog, 1,3-dimethylisoguaninium (1), was isolated from the ethanol (EtOH) extract of the Okinawan sponge Amphimedon paraviridis. The structure was elucidated on the basis of its spectral properties and X-ray crystallographic analysis. Compound 1 exhibited specific inhibition of the basic fibroblast growth factor (bFGF)-induced proliferation of bovine aorta endothelial cells (BAECs). Moreover, compound 1 reduced the tube formation of BAECs in a time-dependent manner.     

Constituents of Holothuroidea, 13. Structure of neuritogenic active ganglioside molecular species from the sea cucumber Stichopus chloronotus

Three ganglioside molecular species, SCG-1, SCG-2, and SCG-3, were obtained from the lipid fraction of the chloroform-methanol extract of the sea cucumber Stichopus chloronotus. On the basis of chemical and spectroscopic evidence, the structures of these gangliosides have been determined to be 1-O-[(N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (SCG-1), 1-O-[8-O-sulfo(major)-(N-acetyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (SCG-2), and 1-O-[alpha-L-fucopyranosyl-(1-->11)-(N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (SCG-3). The ceramide moieties were composed of heterogeneous long-chain base and fatty acid units. SCG-3 is the first type of ganglioside containing a fucopyranose in the sialosyl trisaccharide moiety. Moreover, these three gangliosides exhibited neuritogenic activity toward the rat pheochromocytoma PC12 cells in the presence of nerve growth factor.     

Non-local pseudo-differential operators

The notion of non-local pseudo-differential operators, as well as their symbols and the operation on holomorphic functions, is established and the invertibility theorem for such operators is proved.     

Synthesis of poly[S-(2–9′-acridinylethyl)-L-cysteine] and its TCNQ salt

Poly[S-(2–9′-acridinylethyl)-L -cysteine] ( 5 ) was synthesized by the N-carboxy anhydride procedure. It was converted to the trifluoroacetic acid salt ( 6 ), which was treated with LiTCNQ in methanol to give the TCNQ anion radical salt ( 7 ). 7 showed electrical conductivity of 10^?8 S/cm at 295 K.     

Solution behavior of [(ethylene-co-vinyl alcohol)-g-ethylene oxide] graft copolymers

The solution behavior of hydrophobic-hydrophilic water-soluble graft copolymers consisting of poly[(ethylene-co-vinyl alcohol)-g-ethylene oxide] was investigated by high-resolution NMR spectroscopy and measurements of solution viscosity in tetrahydrofuran, water, and mixtures thereof at various temperatures. A graft copolymer with a backbone containing 2.7 mole% vinyl alcohol exists in an intramolecular phase-separated conformation in aqueous solution, independent of the temperature. Graft copolymers with backbones containing 20.3 mol% vinyl alcohol exhibit an intramolecular mixed-phase conformation in which the mobility of chains in the hydrophobic region depends on temperature. The temperature dependence of the intrinsic viscosity in water shows a maximum near 50°C.