<i>Hydrocleys nymphoides</i> (water poppy): a cosmopolitan aquatic plant with a phytochemical-rich extract exhibiting antimicrobial and antibiofilm activity against multidrug-resistant <i>Staphylococcus</i>

Antimicrobial resistance among Staphylococcus species, including multidrug-resistant and biofilm-forming strains, poses a critical threat to global health, demanding innovative therapeutic solutions. In this context, this study explores the antimicrobial and antibiofilm potential of the aquatic plant Hydrocleys nymphoides as a promising alternative. Extracts from the plant's leaves and roots were obtained using solvents of increasing polarity and tested against five key pathogenic Staphylococcus species: S. aureus, S. epidermidis, S. haemolyticus, S. pseudintermedius, and S. coagulans. The hexane extract of H. nymphoides leaves showed the most notable activity, with inhibition zones of 9-17 mm and minimum inhibitory concentrations (MICs) as low as 0.8 mg/ml for certain strains. Subinhibitory concentrations of the extract significantly reduced biofilm formation in most strains, with reductions up to 46.9%. Gas chromatography-mass spectrometry revealed bioactive compounds such as linoleic acid, n-hexadecanoic acid, 9-octadecenal, eicosane, and tetratriacontane, known for their antimicrobial and antibiofilm properties. Although cytotoxicity was observed at concentrations near the MIC, lower concentrations were non-toxic, indicating potential for controlled therapeutic applications. These findings underscore the biotechnological value of H. nymphoides as a sustainable source of antimicrobial agents against multidrug-resistant Staphylococcus. This work emphasizes the critical role of phytotherapy in combating the escalating antimicrobial resistance crisis.