Standardized microwave extract of Sappan Lignum exerts anti-inflammatory effects through inhibition of NF-κB activation via regulation of heme oxygenase-1 expression

Abstract

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 anti-inflammatory effects of Sappan Lignum prepared by heat-70% EtOH extraction (CSE-H-70E) and microwave-70% EtOH extraction (CSE-MW-70E). High-performance liquid chromatography analysis was used to identify the compounds in these extracts. The heat-70% EtOH and microwave-70% EtOH extracts of Sappan Lignum had different chromatograms. CSE-MW-70E significantly inhibited the protein expression of iNOS and COX-2, PGE 2 , TNF-α, and reduced NO and IL-1β production in macrophages exposed to LPS, whereas, only high concentrations of CSE-H-70E (20 µg/ml) resulted in any effects. Furthermore, CSE-MW-70E upregulated heme oxygenase-1 (HO-1) expression. In addition, the use of tin protoporphyrin, an inhibitor of HO-1, confirmed the inhibitory effects of CSE-MW-70E on pro-inflammatory mediators. These results suggested that the CSE-MW-70E-mediated upregulation of HO-1 played an important role in the anti-inflammatory effects of macrophages. Therefore, these findings showed that microwave extraction can be utilized to improve the extraction efficiency and biological activity of Sappan Lignum.