Four new compounds from Dendrobium devonianum

Two new phenanthrenes dendrodevonin A and B, two new aliphatic acids dendrodevonic acid A and B, along with ten known compounds, were isolated from the stems of Dendrobium devonianum. The structures of new compounds were elucidated on the basis of MS and NMR spectroscopic data, and single-crystal X-ray diffraction analysis. The cytotoxicities of isolates towards HT-29 cell were discussed, and 4-methoxy-2,7-phenanthrenediol exhibited inhibitory activity compared with other studied compounds.