Search

4-Hydroxy-3-methyl-2(1 H )-quinolone ( 1 ), a molecule known for a long time and recently discovered from a Brassicaceae plant Isatis tinctoria without providing sufficient evidence to support the structure, was isolated from a fermentation extract of Burkholderia sp. 3Y-MMP isolated from a soil by a Zn 2+ enrichment culture. Detailed spectroscopic analyses by MS and NMR, combined with 13 C chemical shift comparison with literature values of the related compounds and a synthetic preparation of 1 , allowed its first full NMR characterization and identification of 2-quinolone but not 2-quinolinol ( 2 ) as the preferred tautomer for this heterocyclic system. While the metal-chelating activity was negligible, compound 1 at 10 μM, a concentration lower than that in liquid production cultures, quenched hydroxy radical-induced chemiluminescence emitted by luminol by 86%. Because some Burkholderia species are pathogenic to plants and animals, the above result suggests that 1 is a potential antioxidant to counteract reactive oxygen species-based immune response in the host organisms., (Copyright © 2020, Li et al.; licensee Beilstein-Institut.)