Isopentenylated Bibenzyls and Phenolic Compounds from Dendrobium chrysotoxum Lindl.

Two new isopentenyl bibenzyls, denchrysotonols A and B (1-2), along with 26 known phenolic compounds, were isolated from the stems of cultivated Dendrobium chrysotoxum Lindl. Their chemical structures were clearly elucidated by extensive spectroscopic analysis. Biological evaluation of isolated compounds revealed that phenanthrenes (14, 16-17, 20, and 22) and fluorenone 25 exhibited anti-inflammatory activities which inhibited nitric oxide (NO) production in LPS-activated RAW264.7 macrophages with the IC values ranging from 9.4 to 32.5 μM. Moreover, bibenzyls (1-2 and 7) showed good anti-proliferative activities against triple-negative breast cancer (TNBC) cells (HCC1806, MDA-MB-231, and MB-MB-468) with the IC values ranging from 8.1 to 18.6 μM, of which 1 and 2 seemed preferentially inhibit MDA-MB-231 cells.