Evaluation of Geum urbanum L. Extracts with Respect to Their Antimicrobial Potential

Preparations derived from roots and rhizomes of Geum urbanum L. are traditionally used for the treatment of ulcers and irritations of mucous membranes of the mouth, stomach, and intestinal tract. In complementary medicine, fermentation is one of the methods applied to recover plant extracts used for the production of such pharmaceutical preparations. The present study was performed to characterize the secondary metabolites and to evaluate the antimicrobial potential of different G. urbanum root and rhizome extracts. For this purpose, individual metabolites of fresh and fermented G. urbanum root and rhizome extracts were analyzed by HPLC-DAD-MSn and GC/MS. Among others, rare ellagitannin-sulfates could be characterized by LC/MSn. In addition, the antibacterial activity of various extracts of fresh and dried G. urbanum roots and rhizomes against Staphylococcus aureus (ATCC 6538) and Cutibacterium acnes (CP033842.1; FDAARGOS 503 chromosome) were assessed and compared to that of G. rivale. Furthermore, low- and high-molecular tannins were fractionated by column chromatography, demonstrating the latter to exhibit highest antibacterial activity.