Enjoying instant Chinese herbal medicinal tea
Summer, London 2018. I am a PhD student working on the authentication of Chinese medicinal plants, herbal drugs and substitutes, especially used in the treatment of female disorders. Being part of Plant.ID, I had the opportunity to travel to London, where I got to know an international research community with some of the world’s leading experts in Traditional Chinese Medicine (TCM) and natural product research. I discovered the depth of my scientific field and gained a profound understanding for my research project. I experienced different working environments and became acquainted with the moving work-lifestyle of a scientist.
One of the highlights of my stay was the 6th GP-TCM RA Annual Meeting (Good Practice-TCM Research Association), held at Royal Botanical Gardens, Kew and London South Bank University, UK. The scientific program was entitled "Setting the scene: To provide an overview of the challenges and opportunities facing TCM". Special interest groups presented the challenges of TCM within their research field ranging from regulatory aspects, quality control, pharmacology and toxicology, to clinical studies, and acupuncture. Moreover, I had the chance to learn about the preparation of individualized and complex TCM herbal formulaes at the Division of Herbal and East Asian Medicine of the University of Westminster and came to enjoy my first instant (granule-based) Chinese medicinal tea.
From plant to Chinese herbal tea. TCM herbs are mainly prescribed based on the knowledge documented in the Compedium of Materia Medica and various modern pharmacopoeias. The Compendium Materia Medica (本草綱目) is regarded as the most complete and comprehensive Chinese herbology ever written in the history of Chinese medicine and was first drafted in 1578 during the Ming dynasty. The 52 volumes describe a total of 1892 herbs (items) and 11096 prescriptions (formulae). It incorporates observations of plants, animals, minerals, and other elements with medicinal properties. Li Shizhen’s unique classification system is fascinating, at the same time it serves as a profound reference book and as an inspiration for unsolved mysteries to further research. Authentication and standardization of Chinese herbs and TCM Herbal Products are major challenges for regulating bodies, such as the Chinese, European, United States Pharmacopeias. Species variability, geographical differences, cultivation approaches, harvest time, and various processing methods collectively influence the quality of crude plant materials. Plant constituents resulting in claimed therapeutic effects are often unknown, and the complex composition and preparation of herbal products demand very high sensitivity and multiple assays.
A word about the granules. The demand for consumer convenience has led to a shift from herbal decoction pieces to granules, which are unregulated commercial products for pharmaceutical and medical use and their quality on the EU market is said to be rather doubtful. Besides, TCM granules (vs. TCM herbal drugs) have a rising share in the EU market (30-40% in Germany, Switzerland ca. 80%). TCM granules should meet the quality requirements of the European Pharmacopeia Extract Monograph in terms of identity (TLC/HPTLC-fingerprint, HPLC-fingerprint, DNA identification), purity tests (for mycotoxins, heavy metals, pesticides, microbiological contamination, irradiation, solvent residues) and assays (quantification of toxic constituents, quantification of active markers, labeling).
From metabarcoded paella to metabarcoded TCM formulaes. As said, the authentication of Chinese medicinal plants, herbal drugs and substitutes is challenging. And the joy of drinking a unique tasting cup of Chinese medicinal tea, which can be based on herbal decoction pieces or granules, is only guaranteed if quality and health benefits are assured. We thus seek for standardized novel methods and monographs for the quality control and regulation of TCM herbal products, such as for our favored instant tea. Genetic methods for assuring the species composition of herbal products are in development and are based on sequencing specific regions in the genome, which we call the genetic barcodes, unique strings of genetic codes (e.g., ITS2 or matK, etc.). And my attention is currently caught by a colorful illustrative barcode (see below) from a plant with the nice Chinese Pinyin name: Xiangfu (香附).
We commonly call it nutgrass or Galingale Rhizome, which is the plant species Cyperus rotundus L. Its roots are applied in TCM in the treatment of female disorders. I rise the question, if I can use ITS2 region as a novel universal barcode to trace this species within a complex, poly-herbal batch? Starting off with the analysis of ITS2 in my samples, which are based on TCM formualeas incorporating Xiangfu, I am going to find out if we can potentially use it as a standard DNA barcode for the identification and quantification of poly-herbal TCM mixtures, tablets, and granules. It is to mention that the use of DNA techniques in the identification of granule extracts is very challenging as the DNA is highly degraded. Let’s find out. Finally, I am going to make it my personal challenge to backtrack and examine Xiangfu (香附) by looking at it from different perspectives within the complex, global supply chain of TCM.
Last but not least, I want to rise your attention towards an important issue on Chinese herbs and their global trade. In fact, one of the key lectures of the GP-TCM RA conference, presented by Dr. Christine Leon, was on the conservation and sustainable sourcing of TCM plant species. If the future of plant-based TCM is to be safe-guarded, then the conservation and sustainable sourcing of these plants needs urgent attention. Decades of habitat loss and unsustainable levels of wild-harvesting in China has seen as many as 30% of TCM-Pharmacopoeia plant species threatened with extinction. So far, no label requirements exist to differentiate cultivated versus wild sourced plants. Dr. Christine Leon promotes the goal of GP-TCM RA’s second objective: good practice in TCM research and development, including the use of sustainable sourced materials and she suggests several key components of a strategic, innovative, and a rigorously enforced sustainable sourcing program for TCM plant species. For instance, research and the implementation of Good Practices in Sustainable Herbal Sourcing (GP-SHS) notably by uniting behind "FairWild" certification of TCM herbs in China.
Herbal Medicinal Products are precious for human consumption and we have to create more awareness for our plant resources. New molecular techniques for the identification of plants hold possibilities to contribute to a safer use and to conserve our herbal diversity. Having mentioned this, I round off my blog entry saying that I am happy to keep you on track about my research project and to answer any further questions.