Koji Nagai

Spiruchostatins A and B, novel gene expression-enhancing substances produced by Pseudomonas sp.

Abstract Spiruchostatins A and B were isolated from Pseudomonas sp. as gene expression-enhancing substances. They possess novel bicyclic depsipeptides involving 4-amino-3-hydroxy-5-methylhexanoic acid and 4-amino-3-hydroxy-5-methylheptanoic acid residues, respectively, as shown in Fig. 1 Download high-res image (1KB) Download full-size image Figure 1 . Structures of spiruchostatins A ( 1 ) and B ( 2 ). .

Studies on the distribution of alkalophilic and alkali-tolerant soil fungi II: Fungal flora in two limestone caves in Japan

In a series of studies on the distribution of alkalophilic and alkali-tolerant fungi, soil fungi were isolated from five alkaline calcareous soil samples in two closely located limestone caves (stalactite caves) in Japan using slightly acidic and alkaline media. Some common soil fungi that can grow in alkaline conditions were obtained in high frequencies. The growth response to pH of the isolates revealed that approximately one third (30.8%) of the isolates had the optimum pH in the alkaline range. All isolates of fourAcremonium species and twoChrysosporium species grew well in alkaline conditions, of whichAcremonium sp. andChrysosporium sp. were pronounced alkalophiles. These fungi were thought to be indigenous species in this alkaline environment. The fungal flora in the Japanese alkaline soils was considerably different from the flora reported in alkaline environments in other countries.

Studies on the distribution of alkalophilic and alkali-tolerant soil fungi I

Soil fungi were isolated from two different soil types using alkaline and slightly acidic media (alkaline cornmeal agar (AC-MA), pH 9.7; cornmeal agar (CMA), pH 6.0) to study their distribution. Different species were obtained on each isolation medium. The number of species ofAcremonium andFusarium increased on ACMA, though many species growing well in acidic conditions were not detected on ACMA. Most of the fungi isolated on ACMA, especially from the alkaline soils, were alkalophiles or alkali-tolerants that can grow at pH 10.Acremonium alternatum, A. furcatum, Acremonium sp. 6,Gliocladium cibotii (YBLF 575),Phialophora geniculata, Stachylidium bicolor andStilbella annulata were alkalophilic, of whichAcremonium sp. 6 was the most pronounced alkalophile. Ability to grow under alkaline conditions, as well as under acidic conditions, was common in manyAcremonium species. The use of alkaline medium facilitates the isolation of alkalophilic soil fungi.

Structure of thioviridamide, a novel apoptosis inducer from Streptomyces olivoviridis

A novel apoptosis inducer, thioviridamide, was isolated from an actinomycete identified as Streptomyces olivoviridis. The molecular formula of thioviridamide was determined to be C56H93N14O10S7+ from high-resolution FAB-MS. The structure of thioviridamide was analyzed by NMR spectral analysis including a variety of two-dimensional techniques. COSY and HMBC experiments revealed the presence of a 2-hydroxy-2-methyl-4-oxopentanoyl group and eleven amino acid residues including two novel amino acids, β-hydroxy-N1,N3-dimethylhistidinium and S-(2-aminovinyl)cysteine. 1H-13C long-range correlations observed in the HMBC, CT-HMBC and HMBC-HOHAHA spectra connected the partial structures with seven amide linkages and five thioamide linkages to establish the planar structure of thioviridamide as a unique cyclic peptide.

Pharmacological properties of YM-254890, a specific G α q/11 inhibitor, on thrombosis and neointima formation in mice

The pharmacological properties of YM-254890, a specific G(alpha)q/11 inhibitor, on acute thrombosis and chronic neointima formation after vascular injury have been investigated. FeCl3 was used to induce vascular injury in the carotid artery of mice. For the thrombosis studies, the test drug was either intravenously or orally administered before vascular injury. For the neointima studies, the test drug was orally administered 1 h before and twice daily for 1 week after vascular injury. Histological analysis was then performed 3 weeks later. YM-254890 significantly inhibited ex vivo platelet aggregation 5 min after intravenous bolus injection at 0.03 mg/kg or more, and 1 h after oral administration at 1 mg/kg. YM-254890 significantly inhibited thrombus formation after intravenous bolus injection at 0.03 mg/kg as well as after oral administration at 1 mg/kg, but tail transection bleeding time was significantly prolonged at 0.1 mg/kg for intravenous injection and 3 mg/kg for oral administration. Furthermore, oral administration of YM-254890 dose-dependently inhibited neointima formation 3 weeks after vascular injury with significant effects at 1 mg/kg twice daily for 1 week. Clopidogrel also significantly inhibited neointima formation at its antithrombotic dose, but its inhibitory potency was less than that of YM-254890. However, YM-254890 significantly reduced systemic blood pressure at doses 3 times higher than those that produced significant inhibitory effects on thrombosis and neointima formation. Though the systemic use of YM-254890 may be limited, owing to its narrow therapeutic window, this unique compound is a useful research tool for investigating the physiological roles of G(alpha)q/11 .

Structure of YM-254890, a Novel Gq/11 Inhibitor from Chromobacterium sp. QS3666

Abstract The isolation and structure elucidation of YM-254890, a novel Gq/11 inhibitor from Chromobacterium sp. QS3666, is described. The gross structure was determined by one- and two-dimensional NMR studies and mass spectrometry. YM-254890 is a cyclic depsipeptide containing uncommon amino acids; β-hydroxyleucine (two residues), N,O-dimethylthreonine and N-methyldehydroalanine. YM-254890 exists as a mixture of two conformers in a variety of NMR solvents, and the distinction between major and minor conformers appears to lie in the geometry of the amide bond between 3-phenyllactic acid and N-methyldehydroalanine. The absolute stereochemistery was elucidated by Marfeys analysis and chiral HPLC analysis of the acid hydrolysate of YM-254890.

Thioviridamide, a Novel Apoptosis Inducer in Transformed Cells from Streptomyces olivoviridis

In the course of screening for antitumor antibiotics using 3Y1 rat fibroblasts transformed with adenovirus oncogenes, a new active substance designated thioviridamide was isolated from the culture broth of an actinomycete. The producing organism was identified as Streptomyces olivoviridis on the basis of its culture characteristics and physiological properties. Thioviridamide showed cytotoxicity selectively against Ad12-3Y1 cells (IC50=3.9 ng/ml) and E1A-3Y1 cells (IC50=32 ng/ml), both of which contain the adenovirus E1A oncogene. Significant numbers of Ad12-3Y1 cells treated with thioviridamide contained condensed chromatin and fragmented nuclei, indicating that thioviridamide induced apoptosis.

Structural Elucidation of YM-75518, A Novel Antifungal Antibiotic Isolated from Pseudomonas sp. Q38009

An antifungal antibiotic, YM-75518, was isolated from the fermentation broth of Pseudomonas sp. Q38009. Structural elucidation of YM-75518 was accomplished through extensive 2D NMR spectroscopy including 15N-1H HMQC and 15N-HMBC at natural abundance. YM-75518 consisted of a unique 15-membered macrolactone ring and a methoxy imino structure.

YM-216391, a novel cytotoxic cyclic peptide from Streptomyces nobilis. I. fermentation, isolation and biological activities.

AbstractYM-216391, a novel cyclic peptide, was isolated from the cultured mycelium of Streptomyces nobilis JCM 4274. It was purified by solvent extraction, silica gel and ODS flash column chromatographies, followed by preparative HPLC. YM-216391 dose-dependently inhibited the growth of human cervical cancer HeLa S3 cells with an IC50 value of 14 nM. YM-216391 also showed potent cytotoxic activity against a human cancer cell line panel.

Antithrombotic and thrombolytic efficacy of YM-254890, a Gq/11 inhibitor, in a rat model of arterial thrombosis

We examined the antithrombotic and thrombolytic effects of the G(q/11) inhibitor YM-254890 in an electrically-induced carotid artery thrombosis model in rats. YM-254890 dose-dependently inhibited ex vivo ADP-induced platelet aggregation after i.v. bolus injection. In the thrombosis study, YM-254890 dosedependently prolonged time to occlusion at doses of 3 and 10 g/kg i.v. and decreased occlusion rate at 10 g/kg i.v. In the thrombolysis study, YM-254890 at 30 micro g/kg i.v. shortened the time to reperfusion and prevented reocclusion after thrombolysis with a modified tissue-type plasminogen activator. YM-254890, at 10 micro g/kg and more, significantly improved carotid patency status after thrombolysis. However, at 30 micro g/kg and more, YM-254890 decreased systemic blood pressure. These results suggest that YM-254890 may be effective for treating G(q)-mediated diseases, and that YM-254890 is a useful tool for investigating the biological roles of G(q/11).