Novel bioactive compounds from Actinomycetes: a short review (1988-1992).

Novel secondary metabolites continue to be isolated from Actinomycetes. Their biological activities and chemical structures show a wide range of diversity. This short review provides information on the compounds isolated between 1988 and 1992, and highlights interesting substances discovered during screening.

Cyclic AMP efflux is regulated by occupancy of the adenosine receptor in pig aortic smooth muscle cells.

Cultured pig aortic smooth muscle cells respond to extracellular adenosine by activating adenylate cyclase and by initiating the efflux of cAMP. In the presence of extracellular adenosine, efflux is first order with respect to intracellular cAMP concentration up to at least 125 pmol/10(6) cells. The apparent first-order rate constant for the efflux of cAMP increases in a dose-dependent manner in response to extracellular adenosine or 5-N-ethylcarboxamide adenosine.

2-Epimutalomycin and 28-epimutalomycin, two new polyether antibiotics from Streptomyces mutabilis. Derivatization of mutalomycin and the structure elucidation of two minor metabolites.

A number of derivatives of mutalomycin (1), a naturally occurring polyether antibiotic, have been synthesized. In the desulfurization reaction of the ethylthio derivative (5) of mutalomycin (1) with Raney-nickel we observed an unusual course of the reaction, namely the introduction of a hydroxy group instead of the usual exchange against hydrogen, leading to two reaction products, mutalomycin (1) and 28-epimutalomycin (3). The structure of 3 and 2-epimutalomycin (2), both minor metabolites from the mutalomycin fermentation, were elucidated by X-ray analysis.

Protein kinase C activators of the teleocidin family decrease the IgE-binding capacity of rat basophilic leukemia cells.

The tumor promoters 12-O-tetradecanoylphorbol-13-acetate (TPA) and the teleocidins (TCDs) had similar inhibitory effects on IgE binding onto the membrane of rat basophilic leukemia (RBL)-2H3 cells. The level of expression of the functional IgE Fc receptor (Fc epsilon R), as measured by CELISA, was decreased up to a maximum of 60% within 5 min-1 h of treatment. This inhibition was obtained at concentrations of 0.

Isolation and characterization of DNA-dependent RNA polymerase III from Leishmania mexicana and inhibition by purine analogs.

A DNA-dependent RNA polymerase has been isolated and characterized from the parasitic flagellated protozoan Leishmania mexicana. The initial stages of purification utilized high-ionic-strength extraction and protamine sulfate treatment. The enzyme was further purified by differential elution by heparin-Sepharose, DEAE-Sephadex, and carboxymethyl-Sephadex chromatography.

Mutalomycin, a new polyether antibiotic taxonomy, fermentation, isolation and characterization.

Mutalomycin is a new metal-complexing polyether antibiotic produced by a strain of Streptomyces mutabilis NRRL 8088. The metabolite, a monocarboxylic acid, was isolated as the sodium salt C41H69NaO12. The structure of this polyether was established by X-ray analysis of its potassium salt C41H69KO12.