Nuclear magnetic resonance‐based chemical signature and nutritional discrimination of Macrotyloma uniflorum accessions from the alpine Himalayas

BACKGROUND: Macrotyloma uniflorum (horsegram) is cultivated in the alpine Himalayas for its nutritional benefits. The chemical diversity of M. uniflorum has been explored by several research groups, but none has reported the chemical signature to monitor the identity and quality. To overcome quality control problems and provide more accurate chemotype information, proton nuclear magnetic resonance (¹H‐NMR)‐based chemical signature and tentative metabotype discrimination was studied. RESULTS: Metabolites were identified by characteristic chemical shifts and their correlations in one‐dimensional (1D) and two‐dimensional (2D) nuclear magnetic resonance (NMR) experiments. The identifications were confirmed by reference standards, with in‐house databases, and with public databases. From the analysis of seed samples from eight locations, NMR detected 46 diversified metabolites, including 18 amino acids, nine carbohydrates, three vitamins, seven flavonoids, and nine miscellaneous molecules (fatty acids/choline/phenolics/organic acids/sterols). These metabolites generated a single snapshot chemical signature for M. uniflorum. Greater content of identified metabolites was found at high elevations of 1829 m (55.78 g kg⁻¹) followed by 1000–1150 m (19.30–17.23 g kg⁻¹) and 1150–1450 m (7.33–13.41 g kg⁻¹). Principal component analysis of samples revealed that chemotypes grouped into three distinct clusters. ‘Cluster‐3’ was positively correlated with metabolites and found the best nutritionally enriched chemotype. CONCLUSIONS: A proton nuclear magnetic resonance‐based M. uniflorum chemical signature was generated for the first time. The environmental conditions of 1829 m were most suitable for obtaining nutritionally enriched M. uniflorum crops. Overall, this information could help in the conservation, quality control, product development, and agriculture inventions of M. uniflorum. © 2021 Society of Chemical Industry.