Differing antibacterial and antibiofilm properties of Polypodium vulgare L. Rhizome aqueous extract and one of its purified active ingredients-osladin

Polypodium vulgare L. (Polypodiaceae), the common polypody, is used in Polish traditional medicine as an expectorant to treat cough, chronic nephritis, and pyelonephritis. This is a first study that tests the antimicrobial properties of the osladin contained in P. vulgare rhizome aqueous extract. The osladin was isolated from the aqueous extract by resin column fractionation, crystallization and preparative high-performance liquid chromatography. High-resolution mass spectrometry was used to confirm the identity of osladin. The bacteriostatic and antibiofilm activity of the extract and of purified osladin were investigated using the time-kill kinetic assay and the biofilm assay. These assays were conducted upon the most commonly uropathogenic Escherichia coli strains for humans. P. vulgare rhizome aqueous-phase extract and purified osladin from that extract showed inhibitory effects on the survival and biofilm formation of the uropathogenic bacteria.