Characterization of Maca (Lepidium meyenii/Lepidium peruvianum) Using a Mass Spectral Fingerprinting, Metabolomic Analysis, and Genetic Sequencing Approach

Authors: GENG, P - Ohio University; SUN, J - Ohio University; BRAND, E - Hong Kong Baptist University; FRAME, J - National Institutes Of Health (NIH); MEISSNER, H - National Institutes Of Health (NIH); STEWART, J - Gaia Herbs, Inc; CLARK, S - National Science Foundation (NSF); MILLER, J - National Science Foundation (NSF); Harnly, James - Jim; Chen, Pei; GAFNER, STEFAN - American Botanical Council

Submitted to: Planta Medica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2020
Publication Date: 4/23/2020
Citation: Geng, P., Sun, J., Brand, E., Frame, J., Meissner, H., Stewart, J., Clark, S., Miller, J., Harnly, J.M., Chen, P., Gafner, S. 2020. Characterization of Maca (Lepidium meyenii/Lepidium peruvianum) using a mass spectral fingerprinting, metabolomic analysis, and genetic sequencing approach. Planta Medica. 169:453–468. https://doi.org/10.1055/a-1161-0372.
DOI: https://doi.org/10.1055/a-1161-0372

Interpretive Summary: Maca (Lepidium meyenii, synonym L. peruvianum) is a tuber that grows above 4000 meters in the Andes mountains and is now cultivated at similar altitudes in China. The tuber is used as a food and for medicinal purposes. In Peru, a commercial form of the root is marketed as a supplement after heating, extruding, drying and powdering. Samples of the supplements and raw tubers from Peru and China were collected and analyzed in collaboration with the aid of the American Botanical Council, Gaia Herbs, Hong Kong Baptist University, Natural Health International, Charles Sturt University, TTD International Pty Ltd, and NSF International. Samples were systematically analyzed by direct injection mass spectrometry, metabolite profiling with high resolution chromatography and mass spectrometry, and genetic sequencing. The supplements and tubers from Peru and China were different in composition. In addition, the yellow, red, purple, and black tubers were also chemically distinct. More than 120 compounds were identified including macamides, glucosinolates, amino acids, fatty acids, poly-unsaturated fatty acids, saccharides, and imidazoles. Genetically, all the samples were determined to be the same.

Technical Abstract: Maca (Lepidium meyenii, synonym L. peruvianum) was analyzed using a systematic approach employing principal component analysis (PCA) of flow injection mass spectrometry (FIMS) fingerprints (no chromatographic separation) to guide selection of samples for metabolite profiling and DNA next generation sequencing (NGS). Samples consisted of 39 commercial maca supplements from 11 manufacturers, 31 unprocessed maca tubers grown in Peru and China, and a historic non-tuber maca sample from Peru. PCA of FIMS fingerprints initially placed all the maca samples in 3 classes with similar chemical composition: commercial maca samples, tubers grown in Peru, and tubers grown in China. Metabolite profiling identified 67 compounds in the negative mode and 51 compounds in the positive mode. Compounds identified by metabolite profiling (macamides, glucosinolates, amino acids, fatty acids, poly-unsaturated fatty acids, saccharides, imidazoles) were then used to identify ions in the FIMS fingerprints. The tuber fingerprints were analyzed by factorial multivariate analysis of variance (MANOVA) revealing that black, red, and yellow maca from Peru and black and yellow maca from China were compositionally different with respect to color and country. Critical ions were identified that allowed differentiation of maca between colors from the same country or between two countries with the same color. Genetically, all samples were confirmed to be L. meyenii based on NGS at 3 gene regions (ITS2, psbA, and trnL) and comparison to recorded sequences of vouchered standards.