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

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