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Traditional Chinese medicine: Separation techniques that improve efficacy
November 30, 2023 / The Bio-Works Team
Traditional Chinese medicine (TCM) is an ancient traditional medical system that has developed over thousands of years in China without recorded external influence. TCM includes various treatment methods such as acupuncture, massage, cupping, Qigong, and diet therapy.
The development of traditional Chinese medicine (TCM)
The origin of traditional Chinese medicine (TCM) can be traced back to the Xia, Shang, and Zhou dynasties in ancient China, which have a history of more than 4,000 years. The origin of TCM is closely related to the philosophical thoughts, cultural background, and lifestyle at that time. In primitive society, people had a low standard of living and an insufficient understanding of nature and various plants, so they did not make active choices when eating, leading to many diseases. To solve this problem, people began to try to understand the nature and functions of various plants and gradually formed knowledge about herbal medicine.
With time, traditional Chinese medicine gradually developed into a comprehensive medical system. Traditional Chinese medicine peaked in the Han and Tang dynasties and spread to surrounding countries such as Japan, Korea, and Vietnam.
After thousands of years of development, traditional Chinese medicine has become a medical system with a complete theoretical system and rich practical experience.
Traditional Chinese medicine and its compounds
TCM refers to substances that are used for the prevention, treatment, and diagnosis of diseases, as well as for promoting health and wellness under the guidance of traditional Chinese medicine theory. These substances are primarily derived from natural resources and their processed products, including plants, animals, minerals, and some chemical- and biological-derived drugs, which are rich in polysaccharides, polyphenols, proteins, amino acids, fats, vitamins, and other components.
TCM compounds usually apply a formula composed of two or more ingredients designed for specific diseases, emphasizing the synergistic and guiding role between different ingredients.
The challenges of traditional Chinese medicine
During the development and usage of TCM, challenges were realized due to the complex composition of raw materials and the low ratio of active ingredients to impurities in compound Chinese medicine. As such, it is necessary to conduct in-depth separation and purification of the extract during the production process to ensure quality and safety. In particular, a large proportion of traditional Chinese medicine comes from plants, which can contain pesticides and heavy metals residues. Therefore, the separation and purification process of TCM is particularly important.
Common impurities in liquid traditional Chinese medicine preparations include the following categories:
- General impurities: These are impurities widely distributed in nature that are easily introduced during the production and storage of various drugs, such as acids, bases, moisture, chlorides, sulfates, etc.
- Toxic substances: These include heavy metals, arsenates, aflatoxins, etc. These substances can also affect the stability and efficacy of traditional Chinese medicine preparations.
- Non-toxic and inert substances that do not affect the stability and efficacy of the preparation: These include moisture and iron salts, etc.
- Substances that can reflect the normal production process and storage conditions of the preparation: These include chlorides, sulfates, etc.
These impurities may come from raw materials, excipients, production processes, storage environments, etc. They can affect the quality and stability of TCM preparations, and thus it is necessary to conduct effective separation and purification, as well as quality control, in order to take corresponding measures to ensure the safety and efficacy of TCM preparations.
Common separation and purification techniques applied in TCM
In TCM, several techniques are commonly applied in the purification and separation process, including solvent extraction, precipitation, crystallization, ultrafiltration, and chromatography methods.
Separation is achieved by utilization of the differences in solubility of chemical components in various polar solvents in solvent extraction. Three or four solvents of different polarities are usually selected, and separation is performed stepwise from low to high polarity to achieve purification.
Precipitation is a preliminary separation method performed by adding certain reagents or solvents to the extract to reduce the solubility of certain components to cause them to precipitate. This method may be used in obtaining active ingredients or removing impurities. For instance, the acid-base precipitation method utilizes the property that alkaline components can form salts in acids and dissolve in bases, precipitating in acids and achieving the separation of alkaline components in traditional Chinese medicine. Alternatively, acid components can form salts in bases and dissolve in acids, precipitating in bases and achieving the separation of phenolic, acidic, and lactone components in traditional Chinese medicine.
Most components in traditional Chinese medicine are solid compounds at room temperature. Some of these compounds can be separated and purified through crystallization methods.
Ultrafiltration applies the principle of mechanical sieving and retention, which means that water and small molecular solutes in the solution can pass through the filter material while insoluble particles and colloidal particles are retained.
Chromatography is used to exploit the differences in physical and chemical properties such as molecular shape, molecular weight, charge state, and affinity to separate various components in the feed material. The components are distributed differently between the stationary phase adsorbent and the mobile phase eluent, thus allowing for separation. The chromatographic method has high separation efficiency, wide adaptability, strong parameter selection for separation conditions, and mild operating conditions. It is widely used to separate and purify biological macromolecules and molecules such as proteins, peptides, nucleic acids, polysaccharides, saponins, alkaloids, flavonoids, organic acids, etc. Ion exchange and size exclusion chromatography separation and purification technology are widely used in the large-scale production of flavonoids, alkaloids, and polysaccharide components in TCM with high efficiency and purity.
The applications and outlook of chromatography methods in TCM
In the field of TCM, the applications of chromatographic methods have been widely used to achieve high purity in liquid TCM. For example, in the extraction and purification process of the Chinese medicine "Salvia miltiorrhiza," high-purity tanshinone compounds purified by the chromatographic method have provided strong support for further pharmacological research and clinical applications.
In addition to the application in the extraction and purification of TCM, chromatographic techniques also play an important role in the quality control and identification of TCM. The authenticity and quality of TCM materials can be identified and controlled to ensure the safety and effectiveness of the TCM. For instance, high-performance liquid chromatography (HPLC) is used to analyze and identify the main components of ginseng. By comparing samples from different batches of ginseng, the authenticity and quality can be determined.
By using advanced chromatography techniques and equipment, multiple active components in TCM formulations can be efficiently separated and purified to improve the quality and stability of TCM.
Chromatographic methods have become indispensable tools in the field of TCM research. Effective components in Chinese medicinal materials can be efficiently extracted, separated, and purified by chromatographic methods to achieve high-purity compounds in TCM for clinical applications and research. At the same time, with the continuous development and improvement of chromatography techniques, its application in the field of TCM will continue to grow.
- Frontiers | Extraction, purification, structure, modification, and biological activity of traditional Chinese medicine polysaccharides: A review (frontiersin.org)
- Biological ingredient complement chemical ingredient in the assessment of the quality of TCM preparations
- Danning Ma. The development of traditional Chinese medicine, Journal of Traditional Chinese Medical Sciences 8 (2021) S1-S9
- https://doi.org/10.12677/pi.2021.101003 (Chinese)