Assessment of Peeling of Astragalus Roots Using ¹H NMR- and UPLC-MS-Based Metabolite Profiling

A metabolomic analysis was performed to examine the postharvest processing of Astragalus membranaceus roots with a focus on the peeling procedure using ¹H NMR and UPLC-MS analyses. Principal component analysis (PCA) score plots from the ¹H NMR and UPLC-MS data showed clear separation between peeled and unpeeled <i>Astragalus</i> roots. Peeled roots exhibited significant losses of several primary metabolites, including acetate, alanine, arginine, caprate, fumarate, glutamate, histidine, <i>N</i>-acetylaspartate, malate, proline, sucrose, trigonelline, and valine. In contrast, the peeled roots contained higher levels of asparagine, aspartate, and xylose, which are xylem-related compounds, and formate, which is produced in response to wound stress incurred during postharvest processing. In addition, the levels of isoflavonoids and astragalosides were significantly reduced in peeled <i>Astragalus</i> root. These results demonstrate that metabolite profiling based on a combination of ¹H NMR and UPLC-MS analyses can be used to evaluate peeling procedures used in the postharvest processing of herbal medicines