Five New Biphenanthrenes from Cremastra appendiculata.

Five new biphenanthrenes, cremaphenanthrenes A-E (1-5), along with six known ones, were isolated from the ethanolic extract of the tubers of Cremastra appendiculata (D. Don) Makino (Orchidaceae). Their structures were elucidated on the basis of extensive spectroscopic analyses. All the compounds obtained were tested in vitro for cytotoxic activities against colon (HCT-116), cervix (Hela), and breast (MDA-MB-231) cancer cell lines. They all showed moderate or weak cytotoxicities to the above cancer cell lines.