Antimicrobial dialkylresorcinols from Pseudomonas sp. Ki19

Four dialkylresorcinols (1-4) were isolated from a liquid culture of Pseudomonas sp. Ki19. Compounds 1 and 2, 2-butyl-5-propylresorcinol and 2-hexyl-5-methylresorcinol, respectively, have not previously been isolated from biological sources, whereas 3 and 4, 2-hexyl-5-propylresorcinol (DB-2073) and 2-hexyl-5-pentylresorcinol (resorstatin), both have been found in biological systems. The compounds inhibited Staphyllococcus aureus at concentrations < or = 10 microg/mL as well as the fungi Aspergillus fumigatus and Fusarium culmorum at 50 microg/mL. The formation of possible antimicrobial quinone oxidation products was investigated under bioassay conditions, and they were not found to be responsible for the main antimicrobial activity.