Pyrronazols, metabolites from the myxobacteria Nannocystis pusilla and N. exedens, are unusual chlorinated pyrone-oxazole-pyrroles.
The chlorinated pyrrole-oxazole-pyrones pyrronazol A (1), pyrronazol A2 (2), and pyrronazol B (3) were isolated from Nannocystis pusilla strain Ari7, and two chlorinated pyrrole-oxazole isomers, pyrronazols C1 (4) and C2 (5), were isolated from N. pusilla strain Na a174. HRESIMS, NMR, and X-ray crystallographic analysis was used in the structure elucidation including the absolute configuration of pyrronazol A (1). In addition to pyrronazols, 1,6-phenazine-diol (6) and its glycosyl derivative, 1-hydroxyphenazin-6-yl-α-d-arabinofuranoside (7), were isolated and identified from the culture broth of N. pusilla strain Ari7. When tested for biological activity against bacteria, fungi, and yeasts, 1 showed weak antifungal activity against Mucor hiemalis (MIC 33.3 μg/mL) but no antibacterial activity, while 6 showed weak antibacterial and antifungal activity (MIC 33.3 μg/mL) against some of the strains tested. In cell culture experiments 1 showed no significant cytotoxicity, while 6 was active against several cell lines, especially the human ovarian carcinoma cells SK-OV-3 (LD50 2.59 μM).
Department Microbial Drugs, Helmholtz Centre for Infection Research , Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Rolf
R
Jansen
Sakshi
S
Sood
Volker
V
Huch
Brigitte
B
Kunze
Marc
M
Stadler
Rolf
R
Müller
D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D018360:Crystallography, X-Ray; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D008826:Microbial Sensitivity Tests; D008968:Molecular Conformation; D015394:Molecular Structure; D009089:Mucor / Q000187:drug effects; D009231:Myxococcales / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D011753:Pyrones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D011758:Pyrroles / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
D000935:Antifungal Agents; D010080:Oxazoles; D011753:Pyrones; D011758:Pyrroles