The influence of procyanidins isolated from small-leaved lime flowers (Tilia cordata Mill.) on human neutrophils.

Linden flower is a wildly used plant material among patients in the treatment of common cold symptoms and mucosa inflammations. However, the structure and bioactivity of flavan-3-ol derivatives present in infusions from flowers of Tilia cordata have not been studied so far. The aim of current study was to isolate and identify main procyanidins present in the flowers of small-leaved lime and to evaluate their influence on the inflammatory response of human neutrophils ex vivo. The chemical structure of isolated compounds was established by 1D and 2D NMR experiments. The bioactivity of obtained compounds was tested in human neutrophils model. Cytotoxicity and influence of compounds on apoptosis was established by flow cytometry. The levels of produced cytokines were established by ELISA after stimulation with lipopolysaccharide (LPS). The inhibition of the production of reactive oxygen species was checked by luminol-dependent chemiluminescence method after N-formylmethionyl-leucyl-phenylalanine (f-MLP) induction. The phytochemical work resulted in the isolation of 10 compounds. Compounds were identified as oligomeric procyanidins and their precursor epicatechin. The potential anti-inflammatory activity of compounds was evaluated in the concentration range 5-20 μM. All compounds were able to decrease the production of ROS from f-MLP-stimulated neutrophils. Most of compounds were able to inhibit the LPS-induced release of IL-8. Some trimeric and tetrameric derivatives were also able to decrease the production of MIP-1β. Obtained results partially support the traditional usage of infusion from lime flowers in the treatment of symptoms of inflammation and irritation of mucosa in common cold, pharyngitis and tonsillitis.