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Cistanche deserticola (CD) is one of the two authoritative source plants of Cistanches Herba, a well-known medicinal plant. Herein, 1H NMR spectroscopy was employed to characterize the chemical profile and to distinguish the different parts, as well as to propose a new processing workflow for CD. Signal assignment was achieved by multiple one and two dimensional NMR spectroscopic techniques in combination with available databases and authentic compounds. The upper parts of the plant were distinguished from the lower parts by combining 1H NMR spectroscopic dataset with multivariate statistical analysis. A new processing method that hyphenated steaming with freeze-drying, was demonstrated to be superior to either steaming coupled with oven-drying or direct freeze-drying via holistic 1H NMR-based metabolomic characterization. Phenylethanoid glycosides, mainly echinacoside and acteoside, were screened out and confirmed as the chemical markers responsible for exhibiting the superiority of the new processing workflow, whereas serial primary metabolites, especially carbohydrates and tricarboxylic acid cycle metabolites, were found as the primary molecules governing the discrimination between the upper and lower parts of the plant. Collectively, 1H NMR spectroscopy was demonstrated as a versatile analytical tool to characterize the chemical profile and to guide the in-depth exploitation of CD by providing comprehensive qualitative and quantitative information.

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Dictamni Cortex (Baixianpi) is a commonly used medicinal herb in traditional Chinese medicines (TCMs), possessing various bioactivities. Quinoline alkaloids are regarded as one of the main active components in this herb. In the present study, a more convenient, specific and accurate analytical method using 1 H NMR has been developed for the quantitative determination of dictamnine, one of the main active quinoline alkaloids in Dictamni Cortex. In a less crowded region d 8.0-8.5, the signal of H-5 of dictamnine was well separated from other signals in chloroform-d 1 . The quantity of dictamnine was calculated by means of the integral value of H-5 of dictamnine to that of the known amount of internal standard, pyrazine. This assay was precise and reproducible, with RSDs less than 3%. The recovery results of dictamnine were observed between 92.10 and 108.10% and the limit of detection (LOD) and limit of quantitation (LOQ) were 3.3 mg ml À1 and 13.2 mg ml À1 , respectively. This newly developed method was proven to be highly accurate, precise and robust, for the determination of dictamnine in Dictamni Cortex. The results obtained from 1 H NMR method were also compared with those from conventional HPLC method, and no remarkable difference was found between these two methods. Fig. 1 Chemical structures of dictamnine (D) and pyrazine (internal standard, IS).