Sammendrag
Preparations of Echinacea purpurea (E. purpurea) are widely used for
the management of upper respiratory infections, influenza, and common cold, often
in combination with other conventional drugs. However, the potential of
phytochemical constituents of E. purpurea to cause herb−drug interactions via
ABCB1 and ABCG2 efflux transporters remains elusive. The purpose of this study
was to investigate the impact of E. purpurea-derived caffeic acid derivatives (cichoric
acid and echinacoside) and tetraenes on the mRNA and protein expression levels as
well as on transport activity of ABCB1 and ABCG2 in intestinal (Caco-2) and liver
(HepG2) cell line models. The safety of these compounds was investigated by
estimating EC20 values of cell viability assays in both cell lines. Regulation of
ABCB1 and ABCG2 protein in these cell lines were analyzed after 24 h exposure to
the compounds at 1, 10, and 50 μg/mL. Bidirectional transport of 0.5 μg/mL
Hoechst 33342 and 5 μM rhodamine across Caco-2 monolayer and profiling for
intracellular concentrations of the fluorophores in both cell lines were conducted to
ascertain inhibition effects of the compounds. Cichoric acid showed no cytotoxic effect, while the EC20 values of tetraenes and
echinacoside were 45.0 ± 3.0 and 52.0 ± 4.0 μg/mL in Caco-2 cells and 28.0 ± 4.3 and 62.0 ± 9.9 μg/mL in HepG2 cells,
respectively. In general, the compounds showed heterogeneous induction of ABCB1 with the strongest 3.6 ± 1.2-fold increase
observed for 10 μg/mL tetraenes in Caco-2 cells (p
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