Isolation of novel stilbenoids from the roots of Cyrtopodium paniculatum (Orchidaceae).

Four new stilbenoids, named cyrtopodinone (1), cyrtopodinol (2), and coeludols A and B (3-4) were isolated from the roots of Cyrtopodium paniculatum, together with 21 known stilbenoids derivatives (5-25). Their structures were elucidated by comprehensive spectroscopic analysis including extensive 1D and 2D-NMR techniques. The cytotoxic activities of the isolated compounds were tested on human glioblastoma U-87MG cell line with fluorescence-based image cytometry. Only four compounds (18, 19, 22 and 25) displayed moderate cytotoxicity with IC50 values of 45.2, 39.9, 58.2 and 48.0μM, respectively.