| Summary: | <i>Pseudomonas aeruginosa</i> is one of the most antibiotic multi-resistant bacteria, causing chronic pulmonary disease and leading to respiratory failure and even mortality. Thus, there has been an ever-increasing search for novel and preferably natural antimicrobial compounds. <i>Agrimonia eupatoria</i> L. and <i>Origanum vulgare</i> L. shoots are commonly used as teas or alcoholic tinctures for their human health-promoting and antibacterial properties. Here, we explored the antimicrobial effects of all plant parts, i.e., leaf, flower, stem, and root extracts, prepared in water or in 60% ethanol, against <i>P. aeruginosa</i>. The impact of these extracts on bacterial survival was determined using a luminescent strain of <i>P. aeruginosa</i>, which emits light when alive. In addition, the antimicrobial effects were compared with the antioxidant properties and content of phenolic compounds of plant extracts. Ethanolic extracts of <i>O. vulgare</i> roots and flowers showed the highest antimicrobial activity, followed by <i>A. eupatoria</i> roots. In particular, chlorogenic acid, the ethanolic extract of <i>O. vulgare</i> roots contained high levels of protocatechuic acid, hesperidin, shikimic acid, rutin, quercetin, and morin. The synergistic effects of these phenolic compounds and flavonoids may play a key role in the antibacterial activity of teas and tinctures.
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