[Applications of chromatography in giant complex drug-organism system]

Chromatography is an important branch of analytical chemistry that focuses on the separation and analysis of complex structures. Following more than 100 years of development and improvement, chromatography theory and technology have gradually become sophisticated. It has become a coalition of science, technology, and art. Recently, chromatography has been successfully used in combination with mass spectrometry, nuclear magnetic resonance spectroscopy, and atomic emission spectroscopy. Chromatography and the combination with other techniques has significantly improved the analysis of complex systems, such as the environment, food, petrochemicals, biological specimens, and medicine. As one of the oldest healing systems, Traditional Chinese Medicine (TCM) has served to maintain the health of people in China and worldwide for thousands of years. Therefore, it has become a core representative of traditional Chinese culture. In the past two years, TCM has been widely used to treat COVID-19, especially in patients with mild symptoms. Recently, Chinese government emphasized the inheritance and innovation of TCM and stepped up efforts to promote its modernization. TCM includes herbal medicine, acupuncture, moxibustion, massage, food therapy, and physical exercise, such as Tai Chi. In most cases, the patients are administered a mixture of TCM formulas containing more than two herbal medicines, resulting in a highly complicated compound mixture. There is no doubt that long-term clinical practices have demonstrated the safety and therapeutic effect of TCM. However, the compound mixture must be simplified to identify the active compounds. This is mainly because of the existence of carcinogenic compounds, pesticides, and heavy metal residues introduced through plantation and production processes. Moreover, enzymes within the human system generate further new compounds in response to the entry of the TCM containing thousands of components. Consequently, the complex TCM and organism systems interact with each other, constituting a giant complex drug-organism system. The analysis of this giant complex system is acknowledged as a key aspect in the modernization process of TCM. In the last 20 years, many studies have been conducted to screen and identify effective compounds in TCM. These effective compounds can be either the original compounds or new metabolic components generated in vivo. All these efforts are aimed at simplifying the components of TCM and elucidating the therapeutic mechanism. It is well known that chromatography can provide technical support for complex systems owing to its unique advantage of outstanding separation and analysis capabilities. Therefore, chromatography and its combination with other technologies have become mainstream technologies for promoting the compilation of molecular structure, information, digitalization, and modernization of TCM. This paper reviews the research and application of chromatography and combination technologies in a giant complex TCM formula-organism system. Furthermore, the authors briefly introduce and summarize the understanding, research ideas, and activities of the authors' team on the modernization of TCM. "Liang Guanxi" and "He strategy" are proposed as novel strategies for studying the giant complex drug-organism system. A distinguished technology integrated with mathematical model of causal relation, combined receptor chromatography, identification of chemical molecular structure and evaluating of pharmacological activities was established. It was successfully employed to determine the core effector-response substances of "Liang Guanxi" herb pairs in a giant complex drug-organism system. Subsequently, utilizing the proposed technology of Combination of Traditional Chinese Medicine Molecular Chemistry, the author's team designed and developed four series of innovative drugs. Inspired by the hundred years of chromatography history and thousands of years of TCM culture, the future development of chromatographic technology is expected. Furthermore, the mechanisms of TCM in medical healthcare, prevention, and treatment of diseases are likely be explained through chromatography, leading to a new strategy to realize the molecularization and digitalization of TCM, which is beneficial to the development of original new drugs.