Tiliae flos metabolites and their beneficial influence on human gut microbiota biodiversity ex vivo

ETHNOPHARMACOLOGICAL RELEVANCE

The linden flower (Tiliae flos) has been used for centuries to treat and relieve symptoms of the common cold, throat irritation, and upper respiratory tract disturbances. Traditionally, this herb is administered orally, and thus it undergoes intestinal metabolism. Although it is pharmacopeial plant material, there are no reports about its interaction with human gut microbiota.

AIM OF THE STUDY

The study aimed to determine the interaction between human gut microbiota and the linden flower extracts, resulting in the biotransformation of the extract's constituents and changes in the microbiota composition.

MATERIAL AND METHODS

The linden flower metabolites were obtained by incubation of extract with human faecal slurries from 5 healthy donors. The UHPLC-DAD-MSⁿ analysis determined the composition of raw extract and analysis of microbial metabolites. The intestinal microbiota isolation and sequencing were used to determine changes in microbiota composition. The anti-inflammatory activity was tested using the LPS-stimulated human neutrophils model and ELISA test.

RESULTS

After incubation of linden flower extract with human gut microbiota, twenty metabolites were detected and characterized, and three among them were identified. The extract changed human gut microbiota composition but did not cause dysbiosis (change in the abundance of forty-three genera). Raw extract and their metabolites exhibit different levels of inhibition of cytokines production by LPS-stimulated neutrophils, but the reduction of TNF-α production was observed.

CONCLUSIONS

The linden flower extract has a beneficial influence on human gut microbiota because it promotes increasing the abundance of bacteria responsible for SCFAs production. The anti-inflammatory effect might be linked to both microbiota composition changes and direct activity of bioavailable metabolites. Increased abundance of SCFAs producers may inhibit the production of pro-inflammatory cytokines. A low concentration of phenolic compounds in metabolized linden flower extract and responsible for anti-inflammatory properties, and the multitude of biological and chemical particles and their interactions may weaken these properties.

Characterization of herbal teas containing lime flowers - Tiliae flos by HPTLC method with chemometric analysis

Linden trees are a source of food products called lime flowers (Tiliae flos), traditionally used in the form of infusion for the treatment of feverish colds and coughs. Lime flowers should include flowers of Tilia cordata Mill, T.x europaea L., and T. platyphyllos Scop. or a mixture of these. The aim of current research was to establish a fast, sensitive HPTLC (high-performance thin-layer chromatography) method that would allow the differentiation of material obtained from five species of lime occurring in Europe. The fingerprints for distinguishing these species were established, as well as a key for identification based on a visual evaluation of chromatograms. The results obtained were also subjected to chemometric analyses. It was shown that each species contains characteristic compounds i.e. linarin that can be used for their identification. The method developed can, in theory, be introduced for the quality control or authentication of linden flowers on the European market.