Identifying the compounds that can distinguish between Saposhnikovia root and its substitute, Peucedanum...

Previously, we established a ¹H NMR metabolomics method using reversed-phase solid-phase extraction column (RP-SPEC), and succeeded in distinguishing wild from cultivated samples of Saposhnikoviae radix (SR), and between SR and its substitute, Peucedanum ledebourielloides root (PR). Herein, we performed LC-HR/MS metabolomics using fractions obtained via RP-SPEC to identify characteristic components of SR and PR. One and three characteristic components were respectively found for SR and PR; these components were isolated with their m/z values and retention times as a guide. The characteristic component of SR was identified as 4'-O-β-D-glucosyl-5-O-methylvisamminol (1), an indicator component used to identify SR in the Japanese Pharmacopoeia. In contrast, the characteristic components of PR were identified as xanthalin (2), 4'-O-β-D-apiosyl (1 → 6)-β-D-glucosyl-5-O-methylvisamminol (3), and 3'-O-β-D-apiosyl (1 → 6)-β-D-glucosylhamaudol (4) based on spectroscopic data such as 1D- and 2D-NMR, MS, and specific optical rotation. Among them, 4 is a novel compound. For the correlation between the NMR metabolomics results in the present and our previous report, only 1 and 2 were found to correlate with the chemical shifts, and the other compounds had no correlation. As the chemical shifts for compounds 1, 3, and 4 were similar to each other, especially for the aglycone moiety, they could not be distinguished because of the sensitivity and resolution of ¹H NMR. Accordingly, combining NMR and LC/MS metabolomics with their different advantages is considered useful for metabolomics of natural products. The series of methods used in our reports could aid in quality evaluations of natural products and surveying of marker components.