Kazuyuki Umemura

The synthesis of fragment A of an antibiotic, nosiheptide

Abstract Fragment A derivative (13) of nosiheptide, useful for the total synthesis, was obtained by stepwise introduction of the 2,5-bis{(4-ethoxycarbonyl)-2-thiazolyl} groups and 6-{(2-substituted)-4-thiazolyl} group into 3-hydroxy-5-cyanopyridine(3). The total yield was 7.6% via 14 steps.

Total synthesis of antibiotic karnamicin B1

Abstract The novel antifungal karnamicin B 1 ( 1 ), 5-hydroxy-3,4-dimethoxy-2-{2-(4-oxopentyl)-4-thiazolyl}pyridine-6-carboxamide was first synthesized via the formation of partially methylated trihydroxy pyridine by ring-transformation from the corresponding furan derivative and subsequent regioselective introduction of 2,6-substituents using Meisenheimer-type reaction.

Chemical and Immunochemical Characterization of Polysaccharides of Sasa Veitchii Leaves

A hot water extract of Sasa veitchii is a health-promoting food in general use. To analyze the structure and function of the polysaccharide fraction of the extract, a macromolecular fraction was obtained by dialysis (HMF) and two polysaccharide fractions (NPS and APS) were separated by DEAE-Sephadex chromatography. HMF strongly reacted with human sera and immunoglobulin preparations. All of the IgM, IgG, and IgA classes of antibodies were reacted with HMF. Comparing the reactivity of NPS and APS, NPS showed significantly stronger reactivity to the sera. From physicochemical analysis, their molecular weights are 20,000 and 8,000, respectively. Sugar analyses of the acid hydrolysates indicated rhamnose, arabinose, xylose, mannose, glucose, and galactose in the molar ratio of 1.0 : 2.3 : 1.5 : 3.8 : 0.6 : 5.3 for NPS and 1.0 : 3.0 : 2.6 : 0.8 : 6.3 : 3.0 for APS, and suggested major differences in the ratio of hexoses. APS also contained 2.6% galacturonic acid. Methylation analyses suggested that 1) both NPS and APS have a highly branched structure, 2) only NPS contains galactofuranose residue at the non-reducing terminal. Partial acid hydrolysis of HMF and subsequent dialysis recovered a high molecular weight fraction, but the resulting product had significantly low immunochemical reactivity. Considering the physicochemical and immunochemical analyses, the major epitope structure of NPS was suggested to be galactofuranose residues. Immunochemical reactivity of the polysaccharide is a key molecular mechanism for the health promoting activity of S. veitchii.