Application of 1H-NMR metabolic profiling to the quality control of Traditional Chinese medicine herbs and herbal decoctions.

摘要

Traditional Chinese Medicine (TCM) has over 2500 years of usage, and is the worldwide focus in finding alternative medicine for various chronic diseases. An important element of TCM practice is the application of herbs and herbal decoctions for the management of diseases. However, the adoption of such time-tested remedies of herbal medicine is impeded by the lack of quality controland the absence of scientific proof of their effectiveness.;Currently, raw TCM herbs are graded and priced according to their origins, ages and morphological characteristics, which are still mainly determined by visual or microscopic inspection by experts. However, this method is subjective and cannot be applied to processed medicinal products in the form of tablet, powder or ready-to-consume decoction, which have become increasingly common on the market. Recently developed DNA-based methods cannot distinguish herbs of the same species grown in different regions, and cannot be applied to these products, which primarily consist of water-extracted small-molecule metabolites of the herbs. This thesis explores the use of metabolic profiling to assess the quality of TCM herbs and its decoctions. In contrast to traditional methods that measure specific, pre-defined chemical markers, metabolic profiling seeks to measure all metabolites in an unbiased, high-throughput manner.;Metabonomics, a method for metabolic profiling based on nuclear magnetic resonance spectroscopy (NMR) is applied to water extracts of herbs and herbal decoction, as to evaluate its effectiveness in distinguishing closely-related samples. Based on the quantitative profiles of their primary metabolites, the herbal samples of two genera, Panax (ginsengs) and Angelica (Danggui) can be distinguished according to their species, cultivation regions and preprocessing methods.;A model herbal decoction Danggui Buxue Tang (DBT), an ancient decoction consisting of two herbs, Angelica Sinensis Radix and Astragali Radix, was investigated. Metabolic profiling revealed that the decoction is not merely a mixture of the two herbal extracts. Results showed that the water extract of DBT had a much higher concentration of asparagine than its constituent herbs. This result suggests a need of quality control standards for herbal decoction, and highlights the need to comply with standardized traditional preparation methods for generating such standards. The method was also applied to a commercial DBT product, and discovered lactose as a contaminant that would not have been detected by traditional methods. Overall, this thesis demonstrated that metabolic profiling is an effective method for analyzing TCM products, and can provide an additional dimension for TCM quality control.