Incarviditone: A Novel Cytotoxic Benzofuranone Dimer from Incarvillea delavayi Bureau et Franchet

A novel benzofuranone dimer, named incarviditone ( 1 ), along with known rengyolone ( 2 ), was isolated from Incarvillea delavayi Bureau et Franchet . The structure of the new compound was elucidated on the basis of spectroscopic methods, especially 2D‐NMR and MS analyses. Compound 1 is the first example of a benzofuranone dimer connected by a CC bond, which presents a new C‐skeleton. The cytotoxicities of compounds 1 and 2 were evaluated against the cell lines A549, LOVO, HL‐60, 6T‐CEM, and HepG2. Incarviditone ( 1 ) exhibited cytotoxicity only against HL‐60 and 6T‐CEM cell lines with IC 50 values of 14.8 and 22.2 μg/ml, respectively, while rengyolone ( 2 ) was more active against all cell lines with IC 50 values between 6.7 and 20.2 μg/ml.