ABSTRACT
Taraxacum coreanum Nakai is a dandelion that is native to Korea, and is widely used as an edible and medicinal herb. The present study revealed the neuroprotective effect of this plant against glutamate-induced oxidative stress in HT22 murine hippocampal neuronal cells. Ethanolic extracts from the aerial (TCAE) and the root parts (TCRE) of T. coreanum were prepared. Both extracts were demonstrated, by high performance liquid chromatography, to contain caffeic acid and ferulic acid as representative constituents. TCAE and TCRE significantly increased cell viability against glutamate-induced oxidative stress in mouse hippocampal HT22 cells. Western blot analysis revealed that treatment of HT22 cells with the extracts induced increased expression of the enzyme heme oxygenase-1 (HO-1), compared with untreated cells, in a concentration-dependent manner. Increased HO-1 enzymatic activity, compared with untreated cells, was also demonstrated following treatment with TCAE and TCRE. In addition, western blot analysis of the nuclear fractions of both TCAE and TCRE-treated HT22 cells revealed increased levels of nuclear factor erythroid 2 like 2 (Nrf2) compared with untreated cells, and decreased Nrf2 levels in the cytoplasmic fraction compared with untreated cells. The present study suggested that the neuroprotective effect of T. coreanum is associated with induction of HO-1 expression and Nrf2 translocation to the nucleus. Therefore, T. coreanum exhibits a promising function in prevention of neurodegeneration. Further studies will be required for the isolation and the full characterization of its active substances.
Subject(s)
Heme Oxygenase-1/metabolism , Neurons/drug effects , Neuroprotective Agents/pharmacology , Oxidative Stress/drug effects , Plant Extracts/pharmacology , Taraxacum/chemistry , Animals , Cell Line , Glutamic Acid/metabolism , Heme Oxygenase-1/analysis , Hippocampus/cytology , Hippocampus/drug effects , Hippocampus/metabolism , Mice , Neurons/cytology , Neurons/metabolism , Neuroprotective Agents/chemistry , Neuroprotective Agents/isolation & purification , Plant Extracts/chemistry , Plant Extracts/isolation & purificationABSTRACT
Two chromone glycosides, hyperimone A [7-(beta-D-glucopyranosyloxy)-5-hydroxy-2-(1-methylethyl)-4H-1-benzopyran-4-one (1)] and hyperimone B [7-(beta-D-glucopyranosyloxy)-5-hydroxy-3-methyl-4H-1-benzopyran-4-one (2)], together with six known compounds were isolated from the methanolic extract of the whole plant of Hypericum erectum. 1,3,5,6-Tetrahydroxyxanthone (5) and I3, II8-biapigenin (6) showed moderate hepatoprotective activity with EC(50) values of 160.2 +/- 0.6 microM and 217.7 +/- 1.3 microM, respectively, against tacrine-induced cytotoxicity in HepG2 cells.
