Haliangicin, a novel antifungal metabolite produced by a marine myxobacterium. 1. Fermentation and biological characteristics.

Haliangicin, a novel beta-methoxyacrylate antibiotic with a conjugated tetraene moiety, was isolated from the culture broth of a marine myxobacterium. A bacterium tentatively named as Haliangium luteum required 2-3% NaCl for the growth and production of haliangicin. Haliangicin inhibits the growth of a wide spectrum of fungi but was inactive against bacteria. In mitochondrial respiratory chains, haliangicin interfered the electron flow within the cytochrome b-c1 segment.

Haliangicin, a novel antifungal metabolite produced by a marine myxobacterium. 2. Isolation and structural elucidation.

A novel antifungal antibiotic, haliangicin, was isolated from a culture broth of marine myxobacterium, Haliangium luteum. The planar structure of haliangicin was elucidated by spectroscopic analyses and was shown to be a new polyunsaturated compound containing beta-methoxyacrylate moiety.

New cyclic depsipeptide antibiotics, clavariopsins A and B, produced by an aquatic hyphomycetes, Clavariopsis aquatica. 1. Taxonomy, fermentation, isolation, and biological properties.

Clavariopsins were isolated from the fermentation broth of Clavariopsis aquatica AJ 117363. Clavariopsins are cyclic depsipeptide antibiotics with the molecular weight of 1,153 and 1,139. Clavariopsins showed in vitro antifungal activity against not only Aspergillus fumigatus but also, although to a lesser extent, A. niger and Candida albicans.

New cyclic depsipeptide antibiotics, clavariopsins A and B, produced by an aquatic hyphomycetes, Clavariopsis aquatica. 2. Structure analysis.

The structures of new cyclic decadepsipeptides, clavariopsins A and B, were determined to be cyclo[-(R)-2-hydroxyisovaleryl-L-pipecoyl-L-MeVal-L-Val-L-MeAsp-L-MeIle-L-MeIle-Gly L-MeVal-L-Tyr(OMe)-] and cyclo[-(R)-2-hydroxyisovaleryl-L-pipecolyl-L-Val-L-Val-L-MeAsp-L-Melle-L-MeIle-Gly-L-MeVal-L-Tyr(OMe)-], respectively, by spectroscopic analyses, especially using 2D NMR techniques. The absolute stereochemistry was elucidated by the advanced Marfey's method and chiral HPLC analysis.

Xanthoepocin, a new antibiotic from Penicillium simplicissimum IFO5762.

A new antifungal antibiotic xanthoepocin was isolated from the culture broth of Penicillium simplicissimum IFO5762. Xanthoepocin was obtained from the culture fluid by solvent extraction and chromatographic purification. It showed antibiotic activity against Gram-positive bacteria and yeasts.

Isolation of myxobacteria from the marine environment.

In an attempt to isolate indigenous marine myxobacteria from coastal samples, we obtained two swarm forming bacteria. Both isolates formed cell aggregates which, at least in one isolate, developed to fruiting body-like structures consisting of a mass of myxospore-like cells. The optimum NaCl concentrations for their growth were between 2 and 3%, comparable to the NaCl concentration of seawater. This growth characteristic strongly suggests that the two isolates are specific marine bacteria. The 16S rDNA sequence studies indicated that the two isolates were related to the genus Nannocystis. Based on the phylogenetic distances between branches, we concluded that the isolates should be assigned to two new myxobacterial genera.

Cystothiazoles A and B, new bithiazole-type antibiotics from the myxobacterium Cystobacter fuscus.

New bithiazole-type antibiotics, cystothiazoles A (C20H26N2O4S2) and B (C20H26N2O5S2), have been isolated from a culture broth of the myxobacterium, Cystobacter fuscus. The gross structures of these compounds were elucidated by spectroscopic analysis, and their absolute stereochemistry was determined by chemical degradation of cystothiazole A. Cystothiazole A inhibits fungi and human tumor cells, whereas it is inactive against bacteria. The antifungal activity appears to result from the inhibition of submitochondrial NADH oxidation. Although these compounds are structurally related to the known antibiotic myxothiazol, cystothiazole A was more active against fungi and less cytotoxic than myxothiazol.