Poly p-hydroxybenzyl substituted bibenzyls and phenanthrenes from Bletilla ochracea Schltr with anti-inflammatory and cytotoxic activity

Ten previously undescribed stilbenoids, including six bibenzyls (bleochrins A-F, 1-6), three phenanthrenes derivatives (bleochrins G-J, 7-10) along with eleven known compounds were isolated from the rhizomes of Bletilla ochracea Schltr. The structural characterizations of 1-21 were accomplished by spectroscopic data, while the absolute stereostructure of 6 was confirmed by electronic circular dichroism (ECD) data analyses. All isolated metabolites except 7 were evaluated for cytotoxic activity against five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480). Four isolates exhibited significant inhibitory ability against HL-60, SMMC-7721, and MCF-7 cell lines, with IC50 values ranging from 0.79 to 6.57 mu M. The isolates were tested further for inhibitory effects on the NO production of the liposaccharide (LPS)-induced RAW264.7 macrophages and showed activity with IC50 values at 15.29-24.02 mu M.