Novel macamides from maca (Lepidium meyenii Walpers) root and their cytotoxicity

Maca, Lepidium meyenii Walpers (Brassicaceae), contains secondary metabolites, including macamides, which possess many bioactive properties. Two new macamides, namely, N-benzyl-9-oxo-10E, 12E-octadecadienamide (3) and N-benzyl-9-oxo-10E, 12Z-octadecadienamide (4), were isolated from maca root. In addition, two fatty acid derivatives, 9-oxo-10E, 12E-octadecadienoic acid (1) and 9-oxo-10E, 12Z-octadecadienoic acid (2), were found for the first time from maca. The structures of compounds (3) and (4) were elucidated by spectrometric and spectroscopic methods including UV, IR, H-1 NMR, C-13 NMR, 2D NMR and HR ESI-MS experiments. The novel macamides exhibit inhibitory activity against the proliferation of the HT-29 cancer cell line with IC50 values of 12.8 mu mol/L (3) and 5.7 mu mol/L (4). The two compounds were inactive (IC50 > 50 mu mol/L) towards the proliferation of SGC7901, MCF7, NCI-H460 and HepG2 cancer cell lines.