Preparation from Lepidium meyenii Walpers using high-speed countercurrent chromatography and thermal stability of macamides in air at various temperatures.

Originally cultivated in the Peruvian Andes, Maca (Lepidium meyenii) is now widely consumed as functional food which is known for its functional characteristic like relieving fatigue and enhancing stamina. Macamides are the unique fatty acids with long-chain and N-benzylamides among the various constituents extracted from Maca. N-benzyl-(9Z, 12Z, 15Z)-octadecatrienamide, N-benzyl-(9Z, 12Z)-octadecadienamide, N-benzylhexadecanamide and N-benzyl-9Z-octadecenamide were isolated from crude Maca extracts in two steps by using a combination of high-speed countercurrent chromatography (HSCCC) and semi-preparative HPLC. The four macamides were identified by NMR, UV, HRMS and IR spectra. The thermal stability and autoxidative kinetics for N-benzyl-(9Z, 12Z, 15Z)-octadecatrienamide and N-benzyl-(9Z, 12Z)-octadecadienamide in the air were also studied at various temperatures and the apparent activation energies were 28.4 kJ/mol and 29.9 kJ/mol, respectively. The purity of the isolated macamides was up to 98% and the amount was enough for application as a reference substance.