Phenanthrenes from Dendrobium nobile and their inhibition of the LPS-induced production of nitric oxide in macrophage RAW 264.7 cells.

Bioactivity-guided isolation of the methanol extract of the stems of Dendrobium nobile yielded a new phenanthrene together with nine known phenanthrenes and three known bibenzyls. Their structures were elucidated by analysis of the spectroscopic data including 2D-NMR. All of the isolates were evaluated for their potential to inhibit the LPS-induced production of nitric oxide in murine macrophage RAW 264.7 cells. Compounds 1-4, 7-13 inhibited nitric oxide production with the IC(50) values ranging from 9.6 microM to 35.7 microM.