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

Abstract 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 IC 50 values of 45.2, 39.9, 58.2 and 48.0 μM, respectively.