Anti-inflammatory bibenzyls from the stems of Dendrobium huoshanense via bioassay guided isolation.

The stems of Dendrobium huoshanense have long been used to prevent various diseases, including inflammatory diseases. This study was aimed to explain the anti-inflammatory effect of D. huoshanense stems in LPS-induced RAW 264.7 macrophages and to discover potential anti-inflammatory compounds. Results exhibited that D. huoshanense stems ethanol extract could significantly inhibit LPS-induced production of NO, TNF-α and IL-1β. Based on bioassay guided strategy, four bibenzyls (1-4) were isolated from D. huoshanense stems for the first time. Anti-inflammatory assay showed 1-4 could remarkably inhibit the production of NO in LPS-induced macrophages. Moreover, quantitative RT-PCR analysis displayed that the mRNA levels of iNOs, TNF-α and IL-1β could also be significantly reduced by 1-4. These results suggested that D. huoshanense stems ethanol extract and bibenzyls 1-4 might be well developed as therapeutic agent to prevent inflammatory diseases.