Hordenine: A Novel Quorum Sensing Inhibitor and Antibiofilm Agent against Pseudomonas aeruginosa

Hordenine has antibacterial activity with MIC 2.5 mg/mL against Pseudomonas aeruginosa PAO1.

“It also possesses antibacterial activity, with a minimal inhibitory concentration (MIC) of 2.5 mg/mL against the Pseudomonas aeruginosa PAO1 strain [64].”

Hordenine inhibits biofilm formation in P. aeruginosa PAO1 at concentrations lower than 1.0 mg/kg and enhances the efficacy of netilmicin in biofilm inhibition.

“Additionally, they reported hordenine’s ability to inhibit biofilm formation in the PAO1 strain, with concentrations lower than 1.0 mg/kg, as well as significantly enhance the efficacy of the antibiotic netilmicin in biofilm formation inhibition [64].”

Hordenine disrupts and thins preformed biofilms, especially with netilmicin, and suppresses virulence factors of P. aeruginosa (protease, elastase, pyocyanin, pyoverdine, rhamnolipid, alginate) and downregulates QS-related genes lasI, lasR, rhlI, rhlR by nearly 50%.

“Hordenine is also capable of disrupting and thinning preformed biofilms, especially when combined with netilmicin, and suppressing virulence factors of P. aeruginosa, namely protease and elastase activity, pyocyanin and pyoverdine production, and rhamnolipid and alginate activities, even downregulating QS-related genes lasI, lasR, rhlI, and rhlR by nearly 50% [64].”

Hordenine exposure for 24 h at 0.5, 0.75, and 1.0 mg/mL reduced C4-HSL by 69%, 74%, and 79% compared to control.

“They observed a reduction of 69%, 74%, and 79% for C4-HSL, with respect to the listed concentrations, when compared to control.”

Hordenine at the same concentrations reduced 3-oxo-C12-HSL by 24% to 66%, suggesting interference by hordenine in AHL production.

“They noted a reduction ranging from 24% to 66% for 3-oxo-C12-HSL with the same hordenine concentrations, suggesting interference by hordenine in AHL production.”