Anti-inflammatory bibenzyls from the stems of <i>Dendrobium huoshanense</i> via bioassay guided isolation

Abstract

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