The coprophilic ascomycete Coniochaeta ellipsoidea DSM 13856 forms the new antibiotic coniosetin (1) in surface cultures grown on a medium containing malt extract and oatmeal. The structure of the compound C25H35NO4, MW 413, was determined by 2D-NMR and mass spectrometric studies. Coniosetin belongs to the class of tetramic acids; it consists of a substituted aliphatic bicyclic ring system linked to a tetramic acid subunit through a carbonyl center. The absolute configuration was determined by measuring its circular dichroism spectrum and comparing the data with those of equisetin. Coniosetin has a pronounced antibacterial and antifungal action, inhibiting even multi drug-resistant strains of negative bacteria.An obvious consequence of the development of resistance by pathogenic microorganisms1) is a growing demand for new medicines for the control of infectious diseases. However, a review article by J. J. BRONSON and J.
The new pluramycin-type antibiotics pluraflavin A, C43H54N2O14, pluraflavin B, C43H56N2O15, and pluraflavin E, C36H41NO14 were isolated from cultures of the Saccharothrix species DSM12931. The structures of the novel compounds were elucidated with the aid of 2D NMR and mass spectrometric investigations.The characteristic structural element of pluraflavins A and B is an additional 4-epi-vancosamine unit at position 13 of the anthraquinone-7-pyrone ring system. Pluraflavin E has a carboxyl group in this position. Pluraflavin A has a reactive dimethyl epoxide side chain at position 2 of the anthraquinone-7-pyrone aglycon, which may explain the high activity of the antibiotic.The outstanding biological characteristic of pluraflavin A is its powerful, organ-dependent cytostatic action: the IC50 in the colon carcinoma proliferation assay is in the subnanomolar range.
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