Three new cytotoxic stilbene dimers from .

Three new stilbene dimers, paphiodianthins A-C (1-3), and nine known stilbenes, lignan and flavonoids (4-12) were isolated from the roots and leaves of (Orchidaceae). The structures of new compounds were elucidated from their NMR, HRESIMS and IR spectroscopic data. Cytotoxic activity of all isolated compounds was evaluated by MTT assay against two human cancer cell lines (MCF-7, Caco-2), doxorubicin-resistant and mitoxantrone-resistant MCF-7 sublines, as well as a normal cell line (NIH/3T3). Stilbenes , , and were strongly cytotoxic to both cancer cell lines with IC values ranging from 0.50 to 4.51 µM. Compounds , and were also active against chemotherapy-resistant MCF-7 sublines.