Citrus paradisi and Citrus reticulata essential oils interfere with Pseudomonas aeruginosa quorum sensing in vivo on Caenorhabditis elegans

D'ALMEIDA ROMINA ELISA; SUED NAHIR; ARENA MARIO E

Conferencia; 23rd International C. elegans Conference; 2021

Natural products with anti-quorum sensing (QS) properties are attractive therapeutic agents that could help fight antibioticresistance. C. paradisi and C. reticulata’s Essential Oils (EOs) have been shown to interfere with Pseudomonas aeruginosa QSsignaling in vitro (on acyl-homoserine lactones AHLs production and elastase activity) and biofilm formation leading to anattenuation of the microbial virulence.EOs from Argentina-grown Citrus paradisi (grapefruit) and Citrus reticulata (mandarin) were obtained by cold-pressingand cold-pressing followed by steam distillation. These EOs are complex mixtures of mainly monoterpene (94-98%) andsesquiterpene hydrocarbons and their oxygenated derivatives, with limonene as their main component (88-89.8%).We assessed C. paradisi and C. reticulata’s EOs in their ability to extend the survival of Caenorhabditis elegans infected with P.aeruginosa PA14 and PAO1 and their effect on bacterial growth and biofilm formation. Fast (phenazines-mediated), slow (QSmediated) and HCN-mediated killing mechanisms of C. elegans were studied. Also, a food choice assay was used to study the effect of EOs on AHLs by PA14 in vivo. Mandarin and grapefruit EOs’ toxicity was evaluated assessing C. elegans survival, brood size and body length.Our results showed that mandarin and grapefruit EOs at 0.2 mg/mL were safe for the nematodes, significantly inhibited biofilm formation (up to 50%), and improved worm survival following infection in the three assays evaluated (40-74%) withoutaffecting PA14 and PAO1 growth. The food choice assay revealed a clear preference for PA14 grown in the presence of citrus EOs. C. paradisi EOs were more effective in reducing the virulence of P. aeruginosa in comparison with C. reticulata EOs and limonene, their main component. In addition, we observed no difference between the in vivo activity of EOs of each citrus species obtained by the two methodologies described.In conclusion, targeting the QS system is gaining much attention as an infection control strategy. Therefore C. paradisi and C. reticulata EOs could be proposed as sources of anti-QS agents for controlling human P. aeruginosa infections.