Inhibition of Quorum Sensing and Biofilm Formation in Pathogenic Bacteria by Euphorbiaceae-Derived Phytochemicals Purified Through Column Chromatography

Bacteria use communication systems known as quorum sensing (QS) to coordinate group behaviors such as toxin production and biofilm formation. These processes make infections harder to treat and contribute to antimicrobial resistance. With the rise of multidrug‑resistant (MDR) infections, there is an urgent need for new ways to weaken pathogens without necessarily killing them directly. Plant‑derived compounds are attracting attention because they often contain complex chemical structures that can interfere with microbial communication. Members of the Euphorbiaceae family, long valued in traditional medicine, are rich in flavonoids, terpenoids, and phenolic compounds that show promise as antimicrobial agents. In this study, phytochemicals were extracted from selected Euphorbiaceous plants and purified using column chromatography. Fractions were analyzed with thin‑layer chromatography (TLC), Fourier‑transform infrared spectroscopy (FTIR), and high‑performance liquid chromatography (HPLC) to identify active compounds. Their activity was then tested against common clinical pathogens including Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. To assess effects on QS, the violacein assay was carried out with Photobacteriumviolaceus CV026. Biofilm inhibition was measured using crystal violet staining and further visualized with confocal laser scanning microscopy. The results showed that fractions enriched in flavonoids and terpenoids strongly reduced violacein production and disrupted biofilm formation, yet did not significantly inhibit bacterial growth. This indicates that their action is directed at bacterial signaling rather than direct killing. Fractions from Euphorbia Herta and Phyllanthus amaro’s were particularly effective, with up to 70% biofilm reduction in P. aeruginosa. Microscopy confirmed a clear breakdown of biofilm structure in treated samples. Hydroxylated flavonoids appeared to play a central role in this effect. These findings highlight the potential of Euphorbiaceous phytochemicals as natural ant virulence agents. By targeting communication and cooperation within bacterial populations, they offer a strategy that may slow down the development of resistance while supporting current antibiotics. This work supports further exploration of Euphorbiaceous compounds, including more detailed molecular studies and in vivo testing, to develop new tools against persistent and resistant infections