A new biphenanthrene with cytotoxic activity from (Thunb.) Lindl.

2,7,2'-Trihydroxy-3,4,4'7'-tetramethoxy-1,1'-biphenanthrene (), a previously undescribed biphenanthrene, and five known phenanthrenes, i.e. 2,5-dihydroxy-4-methoxy-9,10-dihydroxyphenanthrene (), 2,4-dihydroxy -7-methoxy-9,10-dihydroxyphenanthrene (), 7-hydroxy-2-methoxy-phenanthrene-1,4-dione (), 7-hydroxy-2-methoxy-9,10-dihydro-phenanthrene-1,4-dione (), and 4,4',7,7'-tetrahydroxy-2,2'-dimethoxy-9,9',10,10'-tetrahydro-1,1'-biphenanthrene () were isolated from the whole plant (stems, leaves, roots and fruits) of (Thunb.) Lindl., which is a medicinal plant of the genus in the Orchidaceae family. The structures of isolates were identified using spectroscopic methods, including NMR and mass spectrometry. Additionally, the cytotoxic potency of all the isolates against human lung cancer A549 cell line was evaluated by an MTT assay. All the isolated compounds showed cytotoxic activities with IC values in the range of 10.20 ± 0.81 to 42.41 ± 2.34 μM. The obtained data highlight the importance of as a source of natural lead compounds for cancer therapy.