Two new monoterpene alkaloid derivatives from the roots of Incarvillea arguta.

Two new monoterpene alkaloid derivatives, incargutosines C (1) and D (2), together with a known compound, argutine A (3) have been isolated from the roots of Incarvillea arguta Royle. The structures of 1 and 2 were established on the basis of 1D and 2D NMR spectroscopic analysis, while the absolute configurations of 1 and 2 were determined by a synthetic method. In addition, the cytotoxicity of 3 was evaluated using four tumor cell lines, A549, LOVO, 6TCEM, and MDA-MB-435 (MDA) by the MTT assay.