Two new 2-alkylquinolones, inhibitory to the fish skin ulcer pathogen Tenacibaculum maritimum, produced by a rhizobacterium of the genus Burkholderia sp.

Abstract

Exploration of rhizobacteria of the genus Burkholderia as an under-tapped resource of bioactive molecules resulted in the isolation of two new antimicrobial 2-alkyl-4-quinolones. (E)-2-(Hept-2-en-1-yl)quinolin-4(1H)-one (1) and (E)-2-(non-2-en-1-yl)quinolin-4(1H)-one (3) were isolated from the culture broth of strain MBAF1239 together with four known alkylquinolones (2 and 4–6), pyrrolnitrin (7), and BN-227 (8). The structures of 1 and 3 were unambiguously characterized using NMR spectroscopy and mass spectrometry. Compounds 1–8 inhibited the growth of the marine bacterium Tenacibaculum maritimum, an etiological agent of skin ulcers in marine fish, offering new opportunities to develop antibacterial drugs for fish farming.

Synthesis and Antimicrobial Activity of Burkholderia-Related 4-Hydroxy-3-Methyl-2-Alkenylquinolones (HMAQs) and Their N-Oxide Counterparts

“…Pleasingly, we found that decreasing the reaction time and temperature to one minute and 70 °C, respectively, avoided isomerization while still allowing full conversion of the starting material (entries 4 to 6). Analytical (HRMS) and spectral ( 1 H and 13 C NMR, Tables 2 and 3) data of HMAQ 1, [18][19][20][21][22]24,25,27 HMAQ 2 (burkholone), 28 and HMAQ 3 19,20,26,27 were in excellent agreement with those published for the isolated natural products.…”

“…The organic phase was dried over anhydrous MgSO4, filtered through Celite ® , and evaporated under reduced pressure. The crude material was purified by silica gel flash chromatography to give ethyl carbonate N-oxides (26)(27)(28). 2-(Hept-2'-en-1'-yl)-3-methylquinolin-4(1H) The reaction was stirred at rt for 1 h and then quenched with the addition of cold water (same volume as the solvent).…”

“…biosynthesize a specific class of AQs, namely 4-hydroxy-3-methyl-2alkenylquinolones (HMAQ, 1-3), which feature a methyl group at C3 and a trans- 2 insaturation at the C2-alkyl chain (Figure 1). [17][18][19][20][21][22][23][24][25][26][27] HMAQs 1 and 3, respectively the heptenyl and nonenyl congeners, exhibit potent antifungal 19,20,22,24,25 and antibacterial 19,27 activities against diverse microorganisms as well as plant growth promoting activities. 22 Furthermore, HMAQs 1 and 3 act confirmation of structural identities and biological activities as well as for sustaining drug discovery and pharmaceutical development.…”

4-Hydroxy-3-methyl-2(1H)-quinolone, originally discovered from a Brassicaceae plant, produced by a soil bacterium of the genus Burkholderia sp.: determination of a preferred tautomer and antioxidant activity

“…Synthetic procedure of 1, UV, IR, 1 H NMR, 13 C NMR, COSY, HSQC, HMBC spectra for natural and synthetic 1, and UV, IR, 1 H NMR, 13 C NMR spectra for synthetic intermediates.…”

“…In the course of our continuing study on bioactive metabolites of less studied bacterial taxa [13], Burkholderia sp. 3Y-MMP, isolated from soil by an exhaustive enrichment culture under Zn 2+ -load, was selected for a detailed chemical study, which resulted in the isolation of 4-hydroxy-3-methyl-2(1H)-quinolone (1, Fig.…”