Chromatography-bioluminescence coupling reveals surprising bioactivity of inthomycin A.

By employing a novel technique for the direct coupling of a bacterial bioassay with chromatography, we discovered a gyrA promotor active compound in myxobacterial extracts and elucidated the structure directly without any isolation step. As a result, we identified inthomycin A as the bioactive substance. Our method is based on a whole-cell bioluminescent reporter gene assay coupled with thin-layer chromatography for primary hit detection and with liquid chromatography (LC)/mass spectrometry or LC/NMR for dereplication and structure elucidation. Previously, inthomycin A has been isolated from Streptomycetes and was associated with the inhibition of cellulose biosynthesis and herbicidal activity. Thus, our findings support the basic principle that completely different microbial phyla are able to synthesize the same natural product. Moreover, our results indicate that inthomycin A affects bacterial DNA supercoiling, which reveals an unexpected bioactivity for this compound. These results can possibly promote further investigation of the biosynthesis as well as the biological activity of inthomycins and related natural products.

Metabolites of orally active NO-independent pyrazolopyridine stimulators of soluble guanylate cyclase.

The pyrazolopyridine stimulators of soluble guanylate cyclase BAY 41-2272 and 41-8543 were oxidised in rats and dogs at their 5-pyrimidinyl-cyclopropyl and -morpholino residue. These metabolites activate the soluble guanylate cyclase, induce vasoelaxation and thereby may contribute to the in vivo activity of BAY 41-2272 and BAY 41-8543.