Biomedical subjects

T Fehr

Publications and source records attributed to T Fehr.

9 recordsLinked to original sources

PubMed1989

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.

Anti-Bacterial Agents↗

PubMed1988

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 0.1 microgram/ml for most TCDs, of 1 microgram/ml for TPA and of 20 micrograms/ml for one TCD (olivoretin A). These molecules also decreased the amount of cell-bound IgE detectable by CELISA on cells that had been coated with IgE prior to TCD treatment. When incubated with RBL-2H3 cells for 30 min-2 h, the TCDs and TPA stimulated serotonin release. Depending on their concentration, they had various effects on IgE-plus antigen-induced serotonin release. It is suggested that the down-regulation of IgE receptor expression by these tumor promoters is mediated through protein kinase C activation and phosphorylation of the Fc epsilon R.

Animals↗

PubMed1977

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. Mutalomycin contains six heterocyclic rings and is structurally related to nigericin. The metabolite is active against gram-positive bacteria and Eimeria tenella (chicken coccidiosis).

Animals↗

PubMed1975