A Feasible ¹H-NMR Quantification Method of Indicator Compounds in Microwave-Processed Reynoutria multiflora Radix and...

Reynoutria multiflora (Thunb.) Moldenke is a commonly used herbal drug in traditional Chinese medicine. Prior literature has indicated that R. multiflora possesses broadband pharmacological activities. According to Taiwan Herbal Pharmacopeia (IV) and previous reports, the dominant components of R. multiflora were 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucopyranoside (THSG) (1) and free anthraquinones such as emodin (2), physcion (3), and rhein (4), which played pivotal roles in the pharmacological effects of herbs. However, the standard analytic method with HPLC-UV took much time to prepare samples and calibration curves based on the standard substances. In this study, a rapid quantitative ¹H-NMR analytic method has been developed, which can quantify the indicator compounds in R. multiflora samples. The method validation data demonstrated the good accuracy and precision of this qNMR method. The feasible analytical method can monitor the contents of indicator compounds in both raw and processed herbs. In addition, this method could be applied to analyze the indicator compounds in the decoction Qi Bao Mei Ran Dan successfully. These results all supported the proposed method as a useful tool for quality control of R. multiflora herbal materials and decoctions. With further refinement, this method could serve as a reference for future standard methods in pharmacopoeias.