Tadahiro Takeda

Stimulation of interleukin-8 production by acidic polysaccharides from the root of Panax ginseng

The root of Panax ginseng C.A. Meyer, is a well-known important Chinese traditional medicine used as a stomachic, tonic, sedative and as an elixir called Ginseng in China and Japan. The precise mechanism of the biological actions of this plant is not fully understood. In order to elucidate the immunomodulating activities of this plant, we examined the direct effects of four of its components, acidic polysaccharides isolated in previous studies, on cytokine (interleukin-8; IL-8) production by a human monocytic cell line, THP-1, and human blood monocytes in vitro, as IL-8 is a potent inflammatory cytokine involved in neutrophil chemotaxis and activation. We found that one component, ginsenan S-IIA, is a potent inducer of IL-8 production by human monocytes and THP-1 cells, and this induction is accompanied by increased IL-8 mRNA expression.

Structural elucidation of novel phosphocholine-containing glycosylinositol-phosphoceramides in filamentous fungi and their induction of cell death of cultured rice cells.

Novel ZGLs (zwitterionic glycosphingolipids) have been found in and extracted from the mycelia of filamentous fungi ( Acremonium sp.) isolated from soil. Five ZGLs (ZGL1-ZGL5) were structurally elucidated by sugar compositional analysis, methylation analysis, periodate oxidation, matrix-assisted laser-desorption ionization-time-of-flight MS, (1)H-NMR spectroscopy and fast-atom bombardment MS. Their chemical structures were as follows: GlcN(alpha1-2)Ins1-P-1Cer (ZGL1), Man(alpha1-6)GlcN(alpha1-2)Ins1-P-1Cer (ZGL2), Man(alpha1-6)Man(alpha1-6)GlcN(alpha1-2)Ins1-P-1Cer (ZGL3), PC-->6Man(alpha1-6)GlcN(alpha1-2)Ins1- P -1Cer (ZGL4), and PC-->6Man(alpha1-6)Man(alpha1-6)GlcN(alpha1-2)Ins1-P-1Cer (ZGL5) (where Cer is ceramide and PC is phosphocholine). In addition, one acidic glycosphingolipid, which was the precursor of ZGLs, was also characterized as inositol-phosphoceramide. The core structure of the ZGLs, GlcN(alpha1-2)Ins1- P, is rather different from those found in other fungi, such as Man(alpha1-2)Ins1- P and Man(alpha1-6)Ins1- P. Interestingly, the terminal mannose residue of ZGL4 and ZGL5 was modified further with a PC group. The presence of PC-containing glycosylinositol-phosphoceramides has not been reported previously in any organism. The ceramide constituents of both ZGLs and acidic glycosphingolipid were essentially the same, and consisted of a 4-hydroxyoctadecasphinganine (phytosphingosine) as the sole sphingoid base and 2-hydroxytetracosanoic acid (>90%) as the major fatty acid. ZGLs were found to cause cell death in suspensions of cultured rice cells. The cell death-inducing activity of ZGLs is probably due to the characteristic glycan moiety of Man(alpha1-6)GlcN, and PC-containing ZGLs had high activity. This study is the first to demonstrate that fungal glycosylinositol-phosphoceramides induce cell death in cultured rice cells.

Induction of NGF synthesis in astrocytes by onjisaponins of Polygala tenuifolia, constituents of Kampo (Japanese herbal) medicine, Ninjin-Yoei-To

The effect of a kampo medicine, Ninjin-yoei-to (NYT; Ren-shen-yang-rong-tang in Chinese) on nerve growth factor (NGF) secretion from the cultured rat astrocytes was examined in vitro. When rat embryo astrocytes were cultured in the presence of NYT for 24 h, the amount of NGF in the medium was significantly increased in a dose dependent manner. Among 14 kinds of component herbs in NYT, the roots of Polygala tenuifolia and roots of Panax ginseng extracts increased NGF levels from the astrocytes. Saponin fraction from the roots of P. tenuifolia enhanced the production of NGF, however phenolic glycoside fraction showed no effect. Onjisaponins A, B, E, F and G as major saponins of the root of P. tenuifolia strongly increased the NGF level, whereas ginsenosides Rb1 and Rg1 did not affect the NGF level. Onjisaponin F also induced ChAT mRNA level in rat basal forebrain cells. These results indicate the possibility that NYT and/or onjisaponins in P. tenuifolia may have potential therapeutic effects for the treatment of Alzheimer disease patients.

Synthetic studies on glycosphingolipids from the Protostomia phyla: Syntheses of arthro-series glycosphingolipids

Glycosphingolipids isolated from larvae of the green-bottle fly, Lucilia caesar, have quite unique structures containing GlcNAcbeta-(1 --> 3)-Man and GalNAcbeta-(1 --> 4)-GlcNAcbeta-(1 --> 3)-Man. We have synthesized two glycosphingolipids, beta-D-GlcNAcp-(1 --> 3)-beta-D-Manp-(1 --> 4)-beta-D-Glcp-(1 --> 1)-Cer and beta-D-GalNAcp-(1 --> 4)-beta-D-GlcNAcp-(1 --> 3)-beta-D-Manp-(1 --> 4)-beta-D-Glcp-(1 --> 1)-Cer. A key reaction in the synthetic sequence is the application of the intramolecular aglycon delivery (IAD) approach for the synthesis of the beta-mannopyranosidic linkages.

Synthesis of a model compound related to an anti-ulcer pectic polysaccharide

A stereocontrolled synthesis of the model compound for an anti-ulcer active polysaccharide (Bupleuran 2IIc) is described. Glycosidation of the disaccharide acceptor, 2-O-acetyl-3-O-benzyl-4-O-(p-methoxybenzyl)-alpha-L-rhamnopyranosyl-(1-- >4)-2,3,6-tri-O-benzyl-alpha-D-galactopyranosyl trichloroacetimidate, with the disaccharide receptor, allyl 3,4-di-O-benzyl-alpha-L-rhamnopyranosyl-(1-->4)-2,3,6-tri-O-benzyl-beta- D-galactopyranoside, using silver triflate (AgOTf) as a promoter gave the desired tetrasaccharide derivative, which was transformed into the acidic tetrasaccharide, corresponding to a segment of the rhamnogalacturonan (Bupleuran 2IIc) polysaccharide, propyl alpha-L-Rha-(1-->4)-alpha-D-GalA-(1-->2)-alpha-L-Rha-(1-->4)-beta-D-GalA , via removal of the corresponding ether and ester protecting groups, followed by oxidation.

Pomegranate juice inhibits sulfoconjugation in caco-2 human colon carcinoma cells

Several fruit juices have been reported to cause food-drug interactions, mainly affecting cytochrome P450 activity; however, little is known about the effects of fruit juices on conjugation reactions. Among several fruit juices tested (apple, peach, orange, pineapple, grapefruit, and pomegranate), pomegranate juice potently inhibited the sulfoconjugation of 1-naphthol in Caco-2 cells. This inhibition was both dose- and culture time-dependent, with a 50% inhibitory concentration (IC(50)) value calculated at 2.7% (vol/vol). In contrast, no obvious inhibition of glucuronidation of 1-naphthol in Caco-2 cells was observed by any of the juices examined. Punicalagin, the most abundant antioxidant polyphenol in pomegranate juice, was also found to strongly inhibit sulfoconjugation in Caco-2 cells with an IC(50) of 45 microM, which is consistent with that of pomegranate juice. These data suggest that punicalagin is mainly responsible for the inhibition of sulfoconjugation by pomegranate juice. We additionally demonstrated that pomegranate juice and punicalagin both inhibit phenol sulfotransferase activity in Caco-2 cells in vitro, at concentrations that are almost equivalent to those used in the Caco-2 cells. Pomegranate juice, however, shows no effects on the expression of the sulfotransferase SULT1A family of genes (SULT1A1 and SULT1A3) in Caco-2 cells. These results indicate that the inhibition of sulfotransferase activity by punicalagin in Caco-2 cells is responsible for the reductions seen in 1-naphthyl sulfate accumulation. Our data also suggest that constituents of pomegranate juice, most probably punicalagin, impair the enteric functions of sulfoconjugation and that this might have effects upon the bioavailability of drugs and other compounds present in food and in the environment. These effects might be related to the anticarcinogenic properties of pomegranate juice.

A novel fucosylated glycosphingolipid from the millipede, Parafontaria laminata armigera.

A novel fucosylated glycosphingolipid (GL-3a) was isolated and purified from whole tissues of the millipede, Parafontaria laminata armigera. Its chemical structure was characterized as Man beta 1-4(Fuc alpha 1-3)Glc beta 1-ceramide (I3 alpha Fuc,MlOse2Cer) by gas-liquid chromatography, permethylation study, partial acid hydrolysis, exoglycosidase degradation, TLC/enzyme-immunostaining, negative fast atom bombardment-mass spectrometry and proton nuclear magnetic resonance spectroscopy. This compound was unique in containing a fucose branch linked to the glucose residue of the disaccharide, mannosylglucose. The ceramide moiety was mainly composed of d17:1 (64.3%) and d18:1 (20.0%) sphingoids, and 22:0 (41.8%), 23:0 (16.4%) and 24:0 (15.8%) fatty acids.

SYNTHETIC STUDIES ON GLYCOSPHINGOLIPIDS FROM THE PARASITE ECHINOCOCCUS MULTILOCULARIS

Novel neutral glycosphingolipids isolated from the metacestodes of Echinococcus multilocularis by Persat, may be expected to be involved in host-parasite interactions. We have synthesized these glycosphingolipid analogues containing 2-branched fatty alkyl residues in place of ceramide. The glycosylation of galactosyl donors 4 and 5 with each of the acceptors 2 and 11 in the presence of N-iodosuccinimide (NIS)/TfOH, and the glycosylation of fucosyl donor 13 with acceptors 12 and 20 in the presence of dimethyl(methylthio)sulfonium triflate (DMTST) gave the desired oligosaccharide derivatives at good yield. The fully per-O-acylated 2-(trimethylsilyl)ethyl glycosides 6, 15, 21, and 26 were converted to glycosylimidates 7, 16, 22, and 27, which were condensed with 2-(tetradecyl)hexadecanol and subsequently deacylated give four target glycosphingolipid analogues.

Studies on the chemical constituents from the roots of Platycodon grandiflorum

Three known monodesmosidic saponins: 3-O-β-d-glucopyranosyl-2β,3β,16α,23,24-pentahydroxyolean-12-ene-28-oic acid, 3-O-β-d-glucopyranosyl polygalacic acid, and 3-O-β-d-glucopyranosyl-(1→3)-β-d-glucopyranosyl polygalacic acid; and two known nonsaponin compounds: a mixed compound of n-tetracosanoic acid (lignoceric acid), n-hexacosanoic acid (cerotic acid), and n-octacosanoic acid, and α-monopalmitin; were isolated for the first time from the root of Platycodon grandiflorum A. DC. together with another seven known compounds: platycoside G1 (3-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl-2β,3β,16α,23,24-pentahydroxyolean-12-ene-28-oic acid 28-O-β-d-xylopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside), deapio-platycodin D, Polygalacin D, deapio-platycodin D3, platycoside A, α-spinasterol, and α-spinasteryl-3-O-β-d-glucopyranoside. Alkaline hydrolysis of platycoside G1 afforded a new monodesmosidic prosaponin: 3-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl-2β,3β,16α,23,24-pentahydroxyolean-12-ene-28-oic acid. Their chemical structures were elucidated on the basis of their spectral data and chemical evidence.

Synthetic studies on novel fucosylated glycosphingolipids from the millipede, Parafontaria laminata armigera

Abstract A novel glycosphingolipid, β- d -Man p -(1→4)-[(α- l -Fuc p -(1→3)]-β- d -Glc p -(1→1)-Cer, from the millipede, Parafontaria laminata armigera , was synthesized. A key reaction of this synthetic procedure is the formation of a spiro-orthoester and its reduction for β-selective mannosylation.