Synergistic antibacterial effect of copper complex and Lythrum salicaria plant Extract

Abstract

The increasing resistance of Pseudomonas aeruginosa to conventional antibiotics necessitates the exploration of novel antimicrobial strategies. This study aimed to evaluate the potential synergistic effects of three copper-based metal complexes (Cu1–Cu3) in combination with an extract of Lythrum salicaria against P. aeruginosa. The antimicrobial efficacy of the individual agents and their combinations was assessed through determination of minimum inhibitory concentrations (MICs) and calculation of the fractional inhibitory concentration index (FICI). The results demonstrated that all tested combinations exhibited an indifferent interaction (FICI between 0.5 and 4), indicating neither synergistic nor antagonistic effects. These findings suggest that, under the tested conditions, the combined application of copper complexes and L. salicaria extract does not enhance antibacterial efficacy against P. aeruginosa, although each agent retains individual antimicrobial potential.