Synthesis of Chitin Oligosaccharides Using Dried <Emphasis Type="Italic">Stenotrophomonas maltophilia</Emphasis> Cells Containing a Transglycosylation Reaction-Catalyzing β<Emphasis Type="Italic">-N-</Emphasis>Acetylhexosaminidase as a Whole-Cell Catalyst

Bacterial strain NYT501, which we previously isolated from soil, was identified as Stenotrophomonas maltophilia, and it was confirmed that this strain produces an intracellular β-N-acetylhexosaminidase exhibiting transglycosylation activity. Several properties of this enzyme were characterized using a partially purified enzyme preparation. Using N,N′-diacetylchitobiose (GlcNAc)₂ and N,N′,N″-triacetylchitotriose (GlcNAc)₃ as substrates and dried cells of this bacterium as a whole-cell catalyst, chitin oligosaccharides of higher degrees of polymerization were synthesized. (GlcNAc)₃ was generated from (GlcNAc)₂ as the major transglycosylation product, and a certain amount of purified sample of the trisaccharide was obtained. By contrast, in the case of the reaction using (GlcNAc)₃ as a substrate, the yield of higher-degree polymerization oligosaccharides was comparatively low.     

A new malyngamide from the marine cyanobacterium Moorea producens

A new malyngamide (1) was isolated along with seven known compounds (2–8) from the marine cyanobacterium Moorea producens collected in Hawaii. Compound 1 represented the first reported malyngamide with a hydroxy moiety at C-7 of the characteristic fatty acid portion of the compound. Compound 1 showed cytotoxicity against L1210 cell line at an IC₅₀ value of 2.9 mM and lethal toxicity against the shrimp Palaemon paucidens at a LD₁₀₀ value of 33.3 mg/kg. The bioactivity of compound 1 was approximately 10–100 times weaker than those of isomalyngamides A and B (3, 4). These results indicated that the methoxy group at C-7 of the fatty acid section confers a degree of bioactivity in malyngamides.     

Asymmetric hydrogenation of methyl 3,5-dioxohexanoate catalyzed by ru-binap complex: a short step asymmetric synthesis of dihydro-60methyl-2-H-pyran-2-one

Hydrogenation of methyl 3,5-dioxohexanoate 3 using Ru₂Cl₄((R) or (S)-binap)₂(NEt₃) as the catalyst gave dominantly anti 3,5-dihydroxyester 9, which was then converted into unsaturated lactone 4. The pathway of the hydrogenation reaction was also investigated.     

Capillary electrochromatographic separation of amino acid enantiomers with molecularly imprinted polymers as chiral recognition agents

The use of molecularly imprinted polymers polymerized in a capillary for the separation of amino acid enantiomers by electrochromatography is described. The substrate-selective polymers were prepared by using l-phenylalanine anilide as print molecule and methacrylic acid as the functional monomer. The treatment of the inside surface of the capillary, the composition of the polymer and the electrochromatographic running conditions were investigated. This preliminary report demonstrated a novel and simple method for capillary electrochromatographic separations of amino acid enantiomers using molecularly imprinted polymers. Received: 9 April 1996 / Revised: 8 August 1996 / Accepted: 8 August 1996     

Synergistic Effects of D‐Glucosamine and Collagen Peptides on Healing Experimental Cartilage Injury

We investigated the synergistic wound‐healing effects of D ‐glucosamine (GlcN) and collagen peptide ( : 10 000 Daltons soluble collagen (S‐Co)) on injured cartilage. A injured cartilage model in rabbit was surgically created. Under general anesthesia, three holes at articular cartilage of the medial trochlear (one hole) and trochlear sulcus (two holes) of a distal femur were created using a high‐speed orthopedic drill. After surgery, rabbits were orally administered with collagen peptide (S‐Co group), GlcN (G group), or both (CoG group) for 2 or 3 weeks. In addition, glycine (Gly group) was administered as a control for the S‐Co group in three rabbits. Control rabbits were provided with water ad lib. After 2 weeks, the holes were filled by fibroblasts and chondroblasts in the treatment group, whereas in the control group, the holes were not filled completely unlike for the treatment group. Even three weeks later, only a small change was seen in the control group. In the group receiving collagen and GlcN, the holes were completely filled by proliferating chondroblasts, remodeling of bony trabeculae was also observed. Image analysis of Safranin O‐ and Alcian blue‐stained specimens showed increased production of proteoglycans and glycosaminoglycans, respectively, not only in the injured site, but also in the normal cartilage in the treated groups. The most enhanced healing of injury and increase in Safranin O and Alcian blue positive materials was observed in the CoG group. As a result, simultaneous administration of collagen and GlcN gave a fairly enhanced healing on restoration of cartilage injuries.

Artificial cartilage injury at the stifle joint of a rabbit. a: proximal hole in trochlear sulcus; b: distal hole in trochlear sulcus; c: medial hole in medial trochlear ridge.     

The absolute configuration of (+)-oxopropaline D by theoretical calculation of specific rotation and asymmetric synthesis

The specific optical rotations of (R)-oxopropaline D calculated by two ab initio MO methods were +52+/-31 degrees and +61+/-29 degrees, respectively, and (+)-oxopropaline D (3) was presumed to have an R-configuration. On the basis of this theoretical result, the reaction of 1-litio-beta-carboline with (R)-glyceraldehyde acetonide followed by oxidation with MnO(2) gave (R)-oxopropaline D acetonide (4a), which was consistent with the previously synthesized (+)-oxopropaline D acetonide (4) in all respects. From the results of theoretical calculations and the experimental synthesis, we determined that natural (+)-oxopropaline D (3) has an R-configuration.     

An electrochemical chlorinative ene-type reaction of isoprenoids

The chlorinative ene-type reaction of isoprenoids ( $\text{1}$ → $\text{2}$ ) has been performed by electrolysis in CH₂Cl₂-H₂O-NaCl system. The reaction provides useful allylic chlorides $\text{2}$ for terpene synthesis in high yields and is affected strikingly by the nature of halide ions and solvents. dl-Theaspirane $\text{2}$$\text{1}$ was prepared from α-dihydroionol $\text{via}$ the electrolysis.     

Ion flotation—spectrophotometric determination of traces of chromium(VI)

Ion flotation is used to concentrate chromium(VI) in the range 3–70μg l^-1 from 14 samples. The chromium(III)—diphenylcarbazone complex formed by reaction with diphenylcarbazide is floated efficiently with sodium lauryl sulfate, and the subsided foam is measured spectrophotometrically after simple dilution. Continuous flotation methods at solution flow rates of 2, 3 and 4 l h^-1 are discussed.     

A monoterpene glucoside and three megastigmane glycosides from Juniperus communis var. depressa

A new monoterpene glucoside (1) and three new natural megastigmane glycosides (2-4) were isolated along with a known megastigmane glucoside (5) from twigs with leaves of Juniperus communis var. depressa (Cupressaceae) collected in Oregon, U.S.A., and their structures were determined on the basis of spectral and chemical evidence. In addition, the antibacterial activities of the isolated components against Helicobacter pylori were also investigated.     

Graft copolymerization of anhydro sugar derivatives from macromolecular halides

Cationic graft copolymerizations of bicyclic acetals, 1,6-anhydro-2,3,4-tri-O-benzyl-β-D -glucopyranose (LGTBE) and 1,6-anhydro-2,3,4-tri-O-methyl-β-D -glucopyranose (LGTME), were investigated with macromolecular carbenium ions formed from polymers that contain reactive halogens. Macromolecular complex catalysts formed from chlorosulfonated polyethylene or poly(isoprene-co-chloromethylstyrene) by the action of phosphorus pentafluoride yielded graft copolymers with low proportions (0.6–16%) of poly(LGTBE) or poly(LGTBE-co-epichlorohydrin) branchings. It was found that macromolecular complex catalysts formed from poly(styrene-co-fluoromethylstyrene) or poly(methyl methacrylate-co-fluoromethylstyrene) by the action of boron trifluoride etherate give graft copolymers with high proportions (up to 80%) of poly(LGTBE) or poly(LGTME) branchings. In addition, the model reactions for the graft copolymerization of LGTBE were examined with organic halide-PF₅, organic halide-AgPF₆, and organic fluoride-BF₃·OEt₂ catalytic systems, of which the last two indicate that the polymerization is effected by a carbenium ion mechanism.