Standardized microwave extract of Sappan Lignum exerts anti­inflammatory effects through inhibition of NF­κB activation via regulation of heme oxygenase­1 expression.

The extract of Sappan Lignum, the heartwood of Caesalpinia sappan L., has been used in medicine to improve blood circulation. Recently, the application of microwave extraction methods has been a major focus of research into the extraction of components from natural sources. In this experiment, we compared the anti­inflammatory effects of Sappan Lignum prepared by heat­70% EtOH extraction (CSE­H­70E) and microwave­70% EtOH extraction (CSE­MW­70E). High­performance liquid chromatography analysis was used to identify the compounds in these extracts. The heat­70% EtOH and microwave­70% EtOH extracts of Sappan Lignum had different chromatograms. CSE­MW­70E significantly inhibited the protein expression of iNOS and COX­2, PGE2, TNF­α, and reduced NO and IL­1ß production in macrophages exposed to LPS, whereas, only high concentrations of CSE­H­70E (20 µg/ml) resulted in any effects. Furthermore, CSE­MW­70E upregulated heme oxygenase­1 (HO­1) expression. In addition, the use of tin protoporphyrin, an inhibitor of HO­1, confirmed the inhibitory effects of CSE­MW­70E on pro­inflammatory mediators. These results suggested that the CSE­MW­70E­mediated upregulation of HO­1 played an important role in the anti­inflammatory effects of macrophages. Therefore, these findings showed that microwave extraction can be utilized to improve the extraction efficiency and biological activity of Sappan Lignum.

Taraxacum coreanum protects against glutamate-induced neurotoxicity through heme oxygenase-1 expression in mouse hippocampal HT22 cells.

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.