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Biomedical subjects

H Naganawa

Publications and source records attributed to H Naganawa.

At least 73 records · Page 4Linked to original sources
PubMed1994

Novel antibiotics, amythiamicins. II. Structure elucidation of amythiamicin D.

The structure of a unique polythiazole-containing cyclic peptide antibiotic, amythiamicin D, was elucidated by chemical degradations and NMR spectral analyses. Acid hydrolysis of amythiamicin D gave one mole of glycine and three new amino acids. Structures of N-acetyl-O-methyl derivatives of these new amino acids were determined by NMR and UV spectral analyses. Connectivities of these amino acids were determined by HMBC experiments.

Acetylation↗
PubMed1994

Novel antibiotics, amythiamicins. III. Structure elucidations of amythiamicins A, B and C.

The structures of novel antimicrobial antibiotics, amythiamicins A, B and C, were elucidated by chemical degradations and NMR spectral analyses. The main frame from C-1 to C-41 of these antibiotics was the same as that of amythiamicin D. Amino acid autoanalyses of amythiamicins A, B and C showed that these have another one mole of serine and proline in comparison with amythiamicin D. Stereochemistries of both amino acids were determined to be L by chiral HPLC. These seryl-prolyl residues in amythiamicins A, B and C are attached at C-41 through an oxazoline ring, amide and ester bond, respectively.

Anti-Bacterial Agents↗
PubMed1994

Aldecalmycin, a new antimicrobial antibiotic from Streptomyces. I. Taxonomy, fermentation, isolation, physico-chemical and biological properties.

A new antibiotic, aldecalmycin, has been discovered in the culture broth of Streptomyces sp. MJ147-72F6. Aldecalmycin was purified by solvent extraction, Diaion HP-20 chromatography, silica gel chromatography, Sephadex LH-20 chromatography, HPLC and centrifugal partition chromatography. The 1H and 13C NMR spectra of aldecalmycin showed the presence of keto-enol tautomers. Aldecalmycin is equipotent in inhibiting the growth of sensitive and methicillin-resistant Staphylococcus aureus (MRSA).

Anti-Bacterial Agents↗
PubMed1994

Aldecalmycin, a new antimicrobial antibiotic from Streptomyces. II. Structure elucidation by NMR studies.

A new antibiotic, aldecalmycin (1) was isolated from the culture broth of Streptomyces sp. MJ147-72F6. The 1H and 13C NMR spectra of 1 were complicated due to the presence of a beta-ketoaldehyde moiety. Therefore, 1 was converted into an ethylene ketal derivative (2) and into a dihydroaldecalmycin (3). These derivatives gave assignable NMR spectra. The planar structure was elucidated by using 1H-1H COSY, 2D-HOHAHA, 1H-13C COSY and HMBC spectra of 2. The conformation of the decalin ring was elucidated by using ID-HOHAHA, NOE difference and NOESY spectra of 3. The geometry of double bond in the side chain was determined by NOE difference and NOESY spectra of 3.

Anti-Bacterial Agents↗
PubMed1994

Aldecalmycin, a new antimicrobial antibiotic from Streptomyces. III. Determination of absolute configuration.

The planar structure of aldecalmycin (1) had been determined in the previous paper, together with the conformations of the substituted trans decalin ring having one double bond and the sugar: beta-glucopyranoside type. The absolute configuration of 1 was a following problem to be solved. X-Ray crystallographic analysis of crystalline 4'-6'-O-benzylidenedihydroaldecalmycin (4) revealed the relative configuration. On the other hand, the stereoisomerism of the sugar was determined to be D by the optical rotation value of tetra-O-acetyl-alpha-methylglucopyranoside derived from 1. These results established the absolute configuration of 1.

Anti-Bacterial Agents↗
PubMed1994

Biosynthesis of antitumor antibiotic, cytogenin.

The biosynthesis of antitumor antibiotic cytogenin, 3-hydroxymethyl-6-methoxy-8-hydroxy-isocoumarin, was studied by feeding 14C- or 13C-labeled compounds to culture of the producing organism, Streptoverticillium eurocidicum MI43-37F11. 14C-Acetate and 14C-methionine were efficiently incorporated into cytogenin as precursors. 13C NMR studies proved that the carbon skeleton of cytogenin is derived from pentaketide intermediate due to head-to-tail condensation of five acetate units and methyl group of 6-OCH3 is derived from methionine. It was suggested that 3-hydroxymethyl and/or 6-methoxy group of cytogenin were metabolized by hydroxylation and/or methylation from three intermediates.

Acetates↗
PubMed1993

Microbial glycosidation of some anthracycline antibiotics by an antibiotic-negative mutant of aclarubicin producer.

Microbial conversion of anthracyclinone monosaccharides using aclarubicin-negative mutant of Streptomyces galilaeus was found to produce anthracyclinone disaccharides which had either rhodinose or 2-deoxyfucose as an additional sugar. By this conversion we obtained twelve new anthracyclines from seven anthracyclines which had rhodosamine, N-monomethyldaunosamine or daunosamine at C-7 as a glycosidic sugar. All products had a reduced cytotoxic activity in comparison with those of parent compounds. However, some of them showed a therapeutically improved antitumor effects against L1210 leukemia in vivo.

Aclarubicin↗
PubMed1993

Isolation, structures, and antifungal activities of new aureobasidins.

Aureobasidins are a group of cyclic depsipeptides with antifungal activity and are produced by Aureobasidium pullulans. Aureobasidins are composed of eight amino acids and one hydroxy acid such as 2-hydroxy-3-methylpentanoic acid (Hmp), and highly lipophilic. Five new aureobasidins, S1, S2a, S2b, S3 and S4, which have higher hydrophilicity in reversed phase HPLC than the known aureobasidins A-R, were discovered in a fermentation broth of A. pullulans R106 by means of on-line liquid chromatography/mass spectrometry with electrospray ionization. We identified the structures of the compounds and studied their antifungal activities. Three of the new aureobasidins, S2b, S3 and S4, which have hydroxylated Hmp as the hydroxy acid, were highly active against Candida spp. and Cryptococcus neoformans.

Amino Acid Sequence↗
PubMed1993

IC101, extracellular matrix antagonist produced by Streptomyces sp. MJ202-72F3. Production, isolation, structure determination and biological activity.

In our search for inhibitors of cell adhesion to components of extracellular matrix (ECM), fibronectin, laminin and collagen type IV, we succeeded in finding a novel cyclic hexadepsipeptide antibiotic, named IC101, which was isolated from cultured mycelium of Streptomyces albulus MJ202-72F3. It was purified by centrifugal partition chromatography, preparative reverse phase HPLC and Sephadex LH-20 and was obtained as a white powder. IC101 strongly inhibited cell adhesion to ECM components, suppressed immune responses in vitro and in vivo, and exhibited antimicrobial activity on Gram-positive bacteria.

Animals↗