IMPACT OF DIFFERENT AMARANTHACEAE EXTRACTS ON THE BIOFILM-FORMING CAPACITY OF SEVERAL BACTERIAL PATHOGENS

Amaranthaceae Juss. family encompasses many edible plants with prominent biological activity. This investigation tested the bioactive properties of ethanolic and methanolic extract of three well-known species: spinach (Spinacia oleracea L.), chard (Beta vulgaris L. subsp. vulgaris), and orache (Atriplex hortensis L.) through the determination of total phenolic and flavonoid content, antioxidant activity, and antibacterial properties. The particular goal was to evaluate the antibiofilm potential of extracts and to demarcate concentration-depending changes in the biofilm-forming category of included bacterial strains. The mass of the chard and orache methanolic extracts gained by maceration are lower in comparison to the mass of ethanolic extracts obtained by the Soxhlet method. In the case of spinach, the results are the opposite. All extracts have an antiradical activity that can be attributed to the established amounts of phenols and flavonoids. Total phenolics in dry leaves ranged from 0.09 to 0.44 mg GAE/g dw, and total flavonoids from 0.42 to 1.9 mg RTE/g dw. All investigated extracts performed inhibitory potential in terms of bacterial growth, while there was no bactericidal effect observed. Values of the minimum inhibitory concentration ranged from 125 µg/ml to 500 µg/ml. Overall results suggested orache extracts as the strongest inhibitory agents. Antibiofilm assays showed that examined extracts of spinach, chard, and orache caused changes in the biofilm-forming capacity of investigated bacterial pathogens. Fluctuations in observed biofilm-forming categories after application of extracts were concentration-dependent.