Water avens (Geum rivale) as a tool for helping with Inflammation (general)

Ethnopharmacological relevance Ellagitannin-rich plant materials are widely used in traditional medicine as effective, internally used anti-inflammatory agents. Due to the not well-established bioavailability of ellagitannins, the mechanisms of observed therapeutic effects following oral administration still remain unclear. The aim of the study was to evaluate if selected ellagitannin-rich plant materials could be the source of bioavailable gut microbiota metabolites, i.e. urolithins, together with determination of the anti-inflammatory activity of the metabolites produced on the THP-1 cell line derived macrophages model. Materials and methods The formation of urolithins was determined by ex vivo incubation of human fecal samples with aqueous extracts from selected plant materials. The anti-inflammatory activity study of metabolites was determined on PMA differentiated, IFN-γ and LPS stimulated, human THP-1 cell line-derived macrophages. Results The formation of urolithin A, B and C by human gut microbiota was established for aqueous extracts from Filipendula ulmaria (L.) Maxim. herb (Ph. Eur.), Geranium pratense L. herb, Geranium robertianum L. herb, Geum urbanum L. root and rhizome, Lythrum salicaria L. herb (Ph. Eur.), Potentilla anserina L. herb, Potentilla erecta (L.) Raeusch rhizome (Ph. Eur.), Quercus robur L. bark (Ph. Eur.), Rubus idaeus L. leaf, Rubus fruticosus L. and pure ellagitannin vescalagin. Significant inhibition of TNF-α production was determined for all urolithins, while for the most potent urolithin A inhibition was observed at nanomolar concentrations (at 0.625 μM 29.2±6.4% of inhibition). Urolithin C was the only compound inhibiting IL-6 production (at 0.625 μM 13.9±2.2% of inhibition). Conclusions The data obtained clearly indicate that in the case of peroral use of the examined ellagitannin-rich plant materials the bioactivity of gut microbiota metabolites, i.e. urolithins, has to be taken under consideration.

Plants used in Swedish traditional medicine to treat inflammatory diseases and/or wounds were selected, based on literature data, for evaluation of inhibitory activity on prostaglandin biosynthesis and platelet activating factor (PAF)-induced exocytosis in vitro. Fifty-nine water extracts from 52 different plants in 28 families were tested. A number of plants, e.g. Calluna vulgaris, Corylus avellana, Geum urbanum, Juniperus communis, Polygonum aviculare, Potentilla erecta and Salix caprea were found to be active in both assays. The most potent cyclooxygenase inhibitors were extracts of Calluna vulgaris, Potentilla erecta and Salix caprea. None of the extracts inhibited just the prostaglandin biosynthesis. In the PAF-test, high inhibition was obtained by 19 extracts, the most potent of which were from Geum rivale, G. urbanum, Solanum dulcamara, Symphytum x uplandicum and Vaccinium vitis-idaea. The in vitro effects in relation to the traditional use, chemical contents and botanical classification, as well as the possibilities and the limitations of the methods are discussed.