Kazuhiro Taguchi

STEREOCONTROLLED SYNTHESIS OF NOVEL PHYTOSPHINGOSINE-TYPE GLUCOSAMINOCEREBROSIDES

Abstract D- ribo -Phytosphingosine 1 was conveniently synthesized from N -benzoyl-D-glucosamine 3 by an improved route in which regioselective O -methanesulfonation and diastereoselective Grignard addition are involved as key steps. Using a synthetic intermediate of 1 , novel D- ribo -phytosphingosine-type glycolipids 2a and 2b , unnatural homologues of antifungal cerebrosides Halicylindrosides, were efficiently synthesized in a stereocontrolled manner.

Covalent immobilization of chitosan derivatives onto polymeric film surfaces with the use of a photosensitive hetero-bifunctional crosslinking reagent

Partially N-acetylated chitosan was covalently immobilized onto polymeric film surfaces using the photosensitive hetero-bifunctional crosslinking reagent, methyl 4-azidobenzoimidate, which was previously attached to the chitosan by the reaction between an imidoester group of the reagent and a free amino group of the chitosan. The grafting was accomplished by irradiating with ultraviolet light the modified chitosan being coated on the film surfaces to photolysis arylazide groups, thus crosslinking the chitosan and the underlying substrate polymer together. For ultraviolet absorption and infrared spectroscopy, the irradiation time of 3 min was found to be sufficient for the photolysis of the azide group. The thickness of the immobilized chitosan layer was estimated to be of the order of 30-150 nm using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The chitosan molecules immobilized on the surfaces could be chemically modified by several reagents and also treated with a heparin solution to form a polyelectrolyte complex on the surface. The ionically bound heparin was partially released into a phosphate buffer solution.

Synthesis of Sphingadienine-type Glucocerebrosides 1

Abstract Sphinga-4,8-dienine derivatives were synthesized from a vinyl-epoxide 5 via three routes. First, reaction of 5 with 2-dodecenyl cyanocuprate afforded a 1:1 mixture of (4E,8E)- and (4E,8Z)-sphingadienine derivatives in high yield. Second, the (4E,8E)-isomer was selectively synthesized via allylic bromide-allylic sulfone coupling followed by desulfonylation. Third, the (4E,8Z)-isomer was selectively synthesized via SN2′-type addition of di(cyanomethyl)copper-lithium followed by Wittig olefination. These synthetic intermediates were converted to sphingadienine-type glucocerebrosides 1a and 1b which have calcium ionophoretic activity.

SYNTHESIS AND PROPERTIES OF NONCYCLIC POLYETHER COMPOUNDS. XVIII, A NONCYCLIC POLYETHER CARRIER EXHIBITING MAGNESIUM ION-SELECTIVE TRANSPORT

Abstract 1,2-Bis [3-( o -carboxyphenoxy)propoxy]-4-t-butylbenzene has been prepared as a carrier which exhibits magnesium ion-selective transport through liquid membranes. In competitive cation transport, this carrier can transport magnesium ion with excellent selectivity, whereas 1,2-bis [2-( o -carboxyphenoxy) ethoxy]-4-t-butylbenzene, which has been prepared for comparison, can selectively transport barium ion. Under various transport conditions the cation transport by this carrier has been investigated. The selectivity for magnesium ion alters with changes of conditions. The cation complex of the carrier has also been prepared and investigated spectroscopically.

Specific adsorption of bitter substances on lipid bilayer-coated piezoelectric crystals

The adsorption of various bitter substances on a lipid bilayer matrix was detected by observing the frequency change of a synthetic bilayer-coated piezoelectric crystal; there was a good correlation between the partition coefficient of the bitter material (between the aqueous phase and the synthetic lipid bilayer film on the crystal) and the bitter taste threshold concentration in the biological cell.

Synthesis and properties of noncyclic polyether compounds. XV. Noncyclic polyether carriers exhibiting potassium-ion-selective transport through liquid membranes: their structures and cation selectivity

Abstract The effects of the structure of noncyclic polyethers on potassium-ion-selective transport have been investigated using several synthetic noncyclic polyethers as carriers for transport through liquid membranes. The K + selectivity of a polyether with an oxytrimethylene group instead of an oxyethylene group decreased significantly. The position of the introduced o -phenylene group affects the cation selectivity of the polyethers. A polyether with a quinolyl terminal group exhibits superior K + selectivity to otherwise identical polyethers with naphthyl or n-butyl terminal groups. Also, the selectivity of a polyether with a 2-methylquinolyl terminal group substituted for the quinolyl terminal group increased appreciably. Furthermore, it will be demonstrated that simultaneous separation of two alkali ions (Li + and K + ) from an aqueous solution containing Li + , Na + and K + ion species could be carried out successfully using both K + - and Li + -selective carriers.

Amyloid formation of native folded protein induced by peptide-based graft copolymer

We report here that a native folded holo‐myoglobin, when incubated with a synthetic amyloidogenic peptide in aqueous solutions, forms fibrils. These fibrils took a cross‐β form (inter‐strand spacing: 4.65 Å and inter‐sheet spacing: 10.65 Å) and bound the amyloidophilic dye Congo red as did the authentic amyloid fibrils. In contrast such fibril formation of myoglobin did not occur in the absence of the peptide. These results suggest the possibility that inter‐molecular interaction of native protein with the amyloidogenic peptide trigger the amyloid formation even for the non‐pathogenic native protein like myoglobin, which itself exists as a globular form, under certain conditions.

pH-Regulated formation of amyloid-like β-sheet assemblies from polyglutamate grafted polyallylamine

A novel artificial protein with simple primary structure, poly(gamma-methyl-L-glutamate)-grafted polyallylamine, has been prepared and the resultant peptide has shown a unique property of pH-regulated conformation and morphology.

Biobased carbon content of resin extracted from polyethylene composite by carbon-14 concentration measurements using accelerator mass spectrometry

An estimation procedure for biobased carbon content of polyethylene composite was studied using carbon-14 (14C) concentration ratios as measured by accelerated mass spectrometry (AMS). Prior to the measurement, additives and fillers in composites should be removed because they often contain a large amount of biobased carbon and may shift the estimation. Samples of resin with purity suitable for measurement were isolated from composites with a Soxhlet extractor using heated cyclohexanone. After cooling of extraction solutions, the resin was recovered as a fine semi-crystalline precipitate, which was easily filtered. Recovery rates were almost identical (99%), even for low-density polyethylene and linear low-density polyethylene, which may have lower crystallinity. This procedure could provide a suitable approach for estimation of biobased carbon content by AMS on the basis of the standard ASTM D 6866. The biobased carbon content for resin extracted from polyethylene composites allow for the calculation of biosynthetic polymer content, which is an indicator of mass percentage of the biobased plastic resin in the composite.

Fabrication of vertically and unidirectionally oriented polypeptide assemblies on self-assembled monolayers by stepwise polymerization

A polypeptide assembly prepared by stepwise polymerization on a self-assembled monolayer consisting of amino-alkanethiol and dialkyl disulfide oriented vertically and unidirectionally to the surface.