Lipophilic 9,10-dehydrofukinone action on pathogenic and non-pathogenic bacterial biofilms. Why is this main volatile metabolite in Senecio?

The effect of a natural sesquiterpene ketone, 9,10-dehydrofukinone (DHF), on pathogenic Staphylococcus aureus and Pseudomonas aeruginosa strains isolated from chronic infectious processes, was the focus of the present study. Lipophilic DHF produced important antibacterial synergistic effects in association with ciprofloxacin (CPX) against two biofilm-forming strains of S. aureus HT1 (FIC = 0.21) and P. aeruginosa HT5 (FIC = 0.05). Hence, this mixture constitutes an excellent strategy to combat these biofilm-producing bacteria that overexpress drug efflux pumps as a resistance mechanism. Additionally, a substantial rise in beneficial Lactobacillus biofilm biomass was determined as a very significant finding of this association. Particularly, a non-pathogenic biofilm increment of 119% was quantified when the mixture was added to a probiotic L. acidophilus ATCC SD-5212 culture. A surface activity enhanced in 71% with respect to untreated L. acidophilus culture was also generated by the DHF and CPX association, and therefore a glycoprotein synthesis induction mediated by the mixture is discussed. The results obtained could help in the development of new selective antibiotics. From an ecological standpoint, the present study strongly suggests that DHF is a polyfunctional organic molecule produced with a high yield in Senecio punae that exerts a positive impact on a non-pathogenic plant bacterium L. plantarum CE105.