At present, the idea of quality control of traditional Chinese medicine is to control the amount of one or several effective components or characteristic components in traditional Chinese medicine as the quality standard of the traditional Chinese medicine or Chinese patent medicine, so as to ensure the quality controllability and stability of these components during sample inspection. By analyzing the published research and review articles, it is found that there are a lot of current situation and existing problems in the research on the quality of traditional Chinese medicine,   As well as the evaluation of mode innovation and technological innovation, it is worth learning and reference.

In the guiding opinions on promoting the healthy development of the pharmaceutical industry issued by the State Council on march4,2016, the requirements of "improving the quality standard system and the national drug standard system with Chinese Pharmacopoeia as the core" were put forward, which pointed out the direction for improving the technical specifications and quality control standards for traditional Chinese medicine, ethnic medicine and drug production in the future, improving the scientificity, rationality and operability of the standards, and strengthening the authority and seriousness of the standards. In order to improve the quality of Chinese traditional medicine and its products, based on the study of the existing quality evaluation methods and existing problems, this paper puts forward the new concept of quality marker of Chinese traditional medicine, in order to discuss with colleagues and resonate.

1     Factors affecting the quality of traditional Chinese Medicine

Quality is the lifeline of all products, and also the lifeline of the quality of traditional Chinese medicine. However, because its quality is affected by many factors, it is extremely important to ensure the quality of traditional Chinese medicine, control the quality of traditional Chinese medicine, strengthen the supervision and management of the variety, cultivation, processing, transportation and storage of the drug market, and ensure the safety of drug use.

1.1   Varietal factor

The variety, quality and quality of traditional Chinese medicine can affect the clinical efficacy, and some even endanger people's life safety. Due to the differences in medication habits and natural conditions in different regions, it is very common for traditional Chinese medicine to have multiple sources, foreign bodies with the same name, and synonyms with the same thing. For example, Aconitum Aconitum, a plant of Ranunculaceae, has been used in the past dynastiesAconitum anthoroideum  The root tubers of dc. are used as medicine, and in some places, the Araceae plant Unicorn lotus is usedTyphonium giganteum  The root tubers of engl. are used as white aconite, and their curative effects are obviously different. Ginseng of AcanthaceaePanax ginseng  C. A. Mey.， It can greatly invigorate the vitality, strengthen the heart and strengthen the mind, stimulate the body fluid and calm the nerves, but phytolaccaceae is found in the marketPhytolacca acinosa  Roxb. root impersonation. There are different records in the past dynasties. 1436 samples of medicinal materials were randomly sampled in the market. DNA bar code identification revealed that 4.2% of them were adulterants; The species with adulterants are mainly concentrated in GinsengGinseng Radix et Rhizoma, Dalbergia odoriferaDalbergiae Odoriferae Lignum, Acorus tatarinowiiAcori Tatarinowii Rhizoma, Inula spiralisInulae Flos, honeysuckleLonicerae Japonicae Flos, acanthopanax senticosusAcanthopanacis CortexBupleurum chinenseBupleuri RadixEtc. Another example is that only 40% of the samples of Rhodiola and its decoction pieces are authentic Rhodiola according to Chinese Pharmacopoeia, and most of them are adulterated.

1.2   Cultivation and ecological conditions of production area

In order to meet the clinical needs, many traditional Chinese medicines are commonly used as cultivated products in China. At present, many cultivated Chinese medicinal materials in China mainly depend on the scattered planting of drug farmers. The planting techniques are extensive and lack of standardized management and technical guidance, resulting in poor germplasm and degradation of variety characteristics. For example, the germplasm degradation of Achyranthes bidentata causes the root of Achyranthes bidentata growing smaller, the lignification variation of Astragalus membranaceus, and the branching variation of Fangfeng root. In addition, the excessive application of pesticides, chemical fertilizers and growth stimulating substances in cultivation has caused the content of pesticide residues and heavy metals in traditional Chinese medicine to exceed the standard, which has affected its quality and is difficult to meet the pharmaceutical standards. Due to different ecological conditions such as climate, soil and water quality, the producing area has become the main factor affecting the quality of traditional Chinese medicine. "Sex changes from place to place", doctors of all ages have attached great importance to the genuine nature of traditional Chinese medicine. The amount of glycyrrhizic acid in Glycyrrhiza uralensis Fisch. Varies by 5 ~ 6 times according to different producing areas. Therefore, different traditional Chinese medicines should choose their suitable ecological environment to ensure high quality and good effect.

1.3   Harvesting and processing factors

The harvesting of traditional Chinese medicine is usually based on the principle of optimizing the quality and maximizing the output of traditional Chinese medicine, but sometimes the two indicators are inconsistent. Therefore, it is necessary to select the appropriate harvesting time and processing method to better ensure the clinical efficacy. For example, the amount of saikosaponin in one-year-old people is higher than that in two-year-old people. Although the length, diameter and number of branches of the latter are higher than that of the former, saikosaponin mainly exists in the thick horn tissue of the cortex, and the proportion of the cortex decreases with the thickening of the root. Herba Artemisiae is mostly collected in spring with a height of 6 ~ 10cm. There is a saying that "Herba Artemisiae Artemisiae in March and Herba Artemisiae in April will be pulled up in May as firewood", which indicates the importance of the harvest time. It was found that the four main choleretic active ingredients of Herba Artemisiae, p-hydroxyacetophenone and inumaric acid A and B were higher from early flowering to fruiting in autumn. Peppermint is harvested at the end of blossom because the amount of menthol in the volatile oil is higher than that at other times. The volatile and active components of Angelica sinensis and Ligusticum chuanxiong are easy to oxidize, and the thickness of their slices will affect the loss of volatile components when they are dried.

1.4   Processing factors

According to the needs of preparation production process and clinical application, traditional Chinese medicine usually needs to be processed. The purpose of processing includes reducing toxicity, increasing efficiency, easing drug resistance and decocting beneficial ingredients. For example, after processing Aconitum, diterpene diester alkaloids are transformed into diterpene monoester alkaloids with low toxicity to achieve the purpose of reducing toxicity. The processing of rhubarb is from raw rhubarb, fried with vinegar, fried with wine, fried, cooked rhubarb to rhubarb charcoal. The chemical components disappear from anthraquinone, bound anthraquinone, free anthraquinone to anthraquinone. The drug properties change from severe diarrhea, slow diarrhea to anti diarrhea. Medicinal materials containing alkaloids, such as tetrahydropalmatine and dehydrocoryline, are salt formed after the preparation of yanhusuo vinegar, which improves their water solubility. After many medicinal materials are made into wine, it is conducive to the migration of substances and the dissolution of effective components. After being roasted with Epimedium oil, the wax in the leaf epidermis was dissolved to increase the dissolution of icariin. In addition, processing of Sophora japonica flower can stabilize the drug properties. For example, processing of Sophora japonica flower can avoid the conversion of rutin by rhamnose invertase. Whether the processing of traditional Chinese medicine is appropriate directly affects the efficacy and the amount of effective substances. For example, Angelica sinensis, Ligusticum chuanxiong, Peucedanum praeruptorum, rhubarb and other Chinese medicinal materials that need to be moistened and sliced, the infiltration process can make the effective ingredients lose with the water and reduce the efficacy. For example, if a kind of medicinal material with thick skin and hard texture is planted, the raw material shall not be used as medicine, but shall be fried and applied. The medicinal properties vary according to the heat of frying. There is also the phenomenon that businesses often pass fake goods for real and shoddy goods for good. These will affect the quality and efficacy of traditional Chinese medicine.

1.5     Factors of transportation and storage conditions

Traditional Chinese medicine is easily affected by air, temperature, humidity and light during storage, storage and transportation, resulting in complex physical and chemical changes. For example, the content of paeonol, the main active ingredient of Paeonia suffruticosa, was only half of the original content after one year of storage, and then decreased by half after four years of storage; Another example is that fresh Asarum has strong antitussive effect, but it has no antitussive effect after half a year of storage.

1.6   Influence of extraction and purification process on quality

The extraction and purification process of traditional Chinese medicine (TCM) is a key link in the quality transfer of TCM, including extraction, separation, concentration, drying and other technological links. The extraction process of traditional Chinese medicine is the re acquisition and purification of chemical substances of traditional Chinese medicine, including the selection and rejection of target components and the changes of components. When designing the extraction and purification scheme of traditional Chinese medicine, we should have the following understanding: (1) the drug properties and traditional curative effects of traditional Chinese medicine are the embodiment of the comprehensive effects of all active components of traditional Chinese medicine, that is, the so-called "systematic nature" of traditional Chinese medicine; (2) The design of extraction and purification process should be based on the basic judgment of effective components, invalid components, toxic components and unknown components; (3) The design of extraction and purification process is based on the physical and chemical properties of the components contained in the medicinal materials and their differences, including molecular size, melting point, boiling point, polarity, solubility, volatility, acidity and alkalinity, chromatographic behavior, etc; (4) The effects of single decocting and combined decocting are different, and there are physicochemical changes between the components, such as solubilization, antagonism, decomposition, precipitation, complexation and chemical combination; (5) The traditional usage of traditional Chinese medicine and its prescriptions is an important basis for the selection of extraction and purification process; (6) The extraction and purification process is the key factor for the quality re formation of traditional Chinese medicine (TCM).

The technological procedures have the following three effects on the efficacy of pharmaceutical preparations: (1) to choose the type, quantity and existing form of effective ingredients; (2) Control the release rate of active ingredients; (3) Directly control the absorption rate of drugs. The crushing, extraction, separation, concentration, drying, preparation methods and process conditions of the preparation process must be determined through continuous experiments. Among them, the application of advanced technologies such as low-temperature extraction, supercritical extraction, microcapsules, microspheres, liposomes, centrifugation and ultrafiltration in traditional Chinese medicine preparations is the key to improve the level of traditional Chinese medicine preparations. Therefore, modern science and technology should be absorbed as much as possible in the reform of dosage forms and technological procedures of traditional Chinese medicine.

1.7   Influence of drug delivery route on quality

To understand and evaluate the quality of traditional Chinese medicine from the perspective of drug safety and effectiveness, we should not evaluate the prototype components of the drug itself in isolation, but further analyze the transmission route and in vivo process of the drug components to understand the final "effective components" of the drug. The chemical components of traditional Chinese medicine are complex. There are five kinds of drug components: (1) the drug components directly enter the blood or act on the target with the prototype; (2) The drug component is only a precursor drug. After oral administration, metabolites are produced through gastrointestinal microbial metabolism and liver metabolism, and the metabolites play a role, such as most glycosides; (3) The drug component is not a direct active component, but plays a role of "intermediary therapy" by activating the secretion of endogenous substances to regulate the "internal stability" imbalance of human diseases; (4) The drug components do not play a role in the human pathological process, but interfere with the micro ecology in the body, and play a therapeutic role by improving the intestinal flora to increase the metabolism of other prototype drugs into effective components; (5) In the process of traditional Chinese medicine in vivo, there are complex interactions between prototype components and metabolites, metabolites and metabolites, prototype components, metabolites and receptor molecules.

1.8   Influence of compound prescription and interaction among components on quality

The effectiveness of traditional Chinese medicine is mostly reflected in clinical compatibility in the form of compound prescription. The effectiveness of traditional Chinese medicine can also be divided into two interrelated elements: drug properties and drug efficacy. Drug properties and drug efficacy are the embodiment of the comprehensive biological effects of the whole chemical substance group of traditional Chinese medicine, and the comprehensive embodiment of the overall attribute of the chemical substance group of the whole traditional Chinese Medicine, that is, the "holistic nature" and "systematic nature" in system theory, rather than the single action of a single chemical component. A single component cannot replace the medicinal properties and efficacy of the original medicinal materials, and "the whole is not simply the sum of all parts". In fact, there is a "efficacy network" in the intervention of pharmaceutical chemical components on human pathological process, and there are many modes of interaction between the components. Therefore, the quality of traditional Chinese medicine is also the comprehensive embodiment of the comprehensive biological effects of the chemical groups of traditional Chinese medicine. The effectiveness of traditional Chinese medicine is ultimately the intervention effect against the pathological process of disease (syndrome), so it is more targeted and purposeful. Traditional Chinese medicine is applied in the form of compound according to the principle of syndrome differentiation and treatment in clinic. The subject (traditional Chinese medicine compound and the object (patient physiology and pathology) are two complex systems. Traditional Chinese medicine prescription has "systematic effect", and the systematic quality of traditional Chinese medicine prescription has "non additive". When evaluating the quality of compound Chinese medicine, there should be an overall idea related to the theory of prescription compatibility.

2   Problems in quality, quality standards and supervision of traditional Chinese medicine products  

2.1   The product quality of traditional Chinese medicine market is worrying

According to the announcement of the food and Drug Administration from January to March 2016, more than 80% of the unqualified drugs due to quality problems are traditional Chinese medicine. According to the results of the five circulars published, there were 714 batches of drugs in total, of which 648 batches were unqualified（Table 1）In particular, the problem of traditional Chinese medicine is serious, which indicates that there are quality problems and further rectification and treatment are needed. What's more, some Chinese patent medicines add a variety of chemical synthetic drugs.

2.2     On the variety of "local standard" to "national standard"

Due to historical reasons, quite a number of varieties from "local standards" to "national standards" have been included in Chinese Pharmacopoeia. The quality standards of "local standards" are low, and the maturity level of products is uneven. Even due to the confidentiality of varieties, or the confidentiality of process or quality when applying for new drugs, the dosages of various medicines of some Chinese patent medicines are not disclosed, and the sources of medicinal plant extracts with clear sources of medicinal materials or medicinal plants are not disclosed. As it is a problem that continues from the previous editions of Pharmacopoeia, it has continued until the 2015 edition. Unscientific, nonstandard or even wrong preparation processes and quality standards cannot be changed, which brings difficulties to quality supervision and quality inspection.

2.3   Scientificity of standard formulation of Chinese pharmacoeia

The prescriptions of Chinese patent medicines derived from classical prescriptions or modern clinical famous prescriptions, some of which have been modified in taste and some have changed in compatibility. Therefore, in addition to considering the factors of medicinal materials, the addition and subtraction of such drugs or the change of compatibility will affect the safety and effectiveness of drugs, and also affect the formulation of quality standards for finished drugs. This is the problem of choosing the substances related to the efficacy for qualitative and quantitative determination and establishing quality standards. Through reading and analyzing the first volume of Chinese Pharmacopoeia (2010 edition and 2015 Edition), it is found that there are three problems that are difficult to be used for quality control of listed products: (1) the correlation between the quality of raw materials and finished medicines, and the amount of effective ingredients in Chinese patent medicine preparations is not matched with the amount of medicinal materials (decoction pieces) or extracts used. (2) According to the compatibility principle of traditional Chinese medicine, the position of the same medicinal material in different preparations is different. Some preparations use quantitative indicators that violate the compatibility principle, and only use well determined chemical components for quantitative control. For example, in many preparations, regardless of the position of peony in the prescription, the quantity of paeoniflorin is selected as the quality control index when red peony or white peony is used; Even the amount of licorice component of "Shi" drug is used as the quality control index in the compound composed of multiple drugs. Some do not take "Jun" drug ingredients as quality control indicators at all. (3) The quality comparability and substitutability of the same name varieties. It is found in Chinese Pharmacopoeia that the compound preparations with the same prescription are made into products of different dosage forms. In terms of the same dosage and the same route of administration, the different dosage forms of drugs with the same name are replaceable. However, it is difficult to explain the substitutability of different dosage forms due to the different standards and quality control indicators of the collected varieties of Chinese patent medicines with the same name and different dosage forms. In the 2015 edition of Chinese Pharmacopoeia, there are 63 Chinese patent medicines of the same name with more than 3 dosage forms, forming 222 varieties. Qualitative identification and quantitative determination exist in quite a number of varieties of the same name in different dosage forms, and there are great differences in the number of components and quantitative determination indicators.

2.4   Quality standard and quality monitoring process

Quality is the guarantee of curative effect and the embodiment of process. Quality standard is the indicator of good or bad drug quality. Modernization of traditional Chinese medicine production and scientization of quality standard are the key to the development of traditional Chinese medicine. Due to the complexity of effective components and multiple curative effects of traditional Chinese medicine, according to the accumulation of traditional experience, the role of traditional Chinese medicine on people emphasizes integrity, complementarity and coordination. At present, the level of quality standard of traditional Chinese medicine preparations is relatively low. Therefore, how to use modern analytical techniques and traditional identification experience to formulate diversified controllable indicators that can guide production operations and reflect the uniformity, effectiveness, stability and reproducibility of the internal quality of products is the key and difficult point to improve the quality of traditional Chinese medicine preparations and promote the modernization of traditional Chinese medicine.

In the standardized implementation, the personnel quality and technical level are also important factors. The product quality of traditional Chinese medicine preparations depends on the joint efforts of traditional Chinese medicine technicians and managers. They are required to provide services in all links of traditional Chinese medicine research, technical engineering, production, storage and sales, of which the role of decision makers is particularly important. Managers should establish a people-oriented idea and pay attention to the improvement and training of the basic quality of all kinds of personnel.

2.5   Doctor's individualized prescription

Prescription is the basis and basis for the study of traditional Chinese medicine preparations, and is the main factor affecting the efficacy of traditional Chinese medicine preparations. Whether it is an ancient prescription, an experimental prescription or a hospital agreed prescription, the traditional Chinese medicine flavor, the dosage ratio between different flavors and the daily dosage must be screened before the preparation of the preparation, so as to make the prescription as refined and rigorous as possible, in line with the principles of TCM syndrome differentiation and treatment, and the principle of rational and legal prescriptions.

Doctor's prescription is an individualized treatment prescription issued by traditional Chinese medicine according to the treatment principles and methods of traditional Chinese medicine. Its curative effect is closely related to the compatibility and application of the increase or decrease of the flavor of the prescription. Due to the large number of factions of traditional Chinese medicine, different understanding of syndromes, different treatment principles and methods, and different prescription groups, 10 doctors can prescribe 10 prescriptions for the same patient and the same disease (different prescription groups and different doses). There are often (1) some hospitals develop prescription drugs into hospital preparations to become "internal products" for clinical treatment. Due to the different conditions of each hospital and the quality of the purchased decoction pieces, there is a blind spot on how to ensure the quality of these hospital preparations and carry out quality control; (2) Some hospitals set up the decocting business of traditional Chinese medicine. Due to the differences in personnel and conditions, how to ensure the decocting quality and achieve the purpose of individual treatment of prescriptions is also worth paying attention from the perspective of quality. Such as whether the control of boiling time, temperature, water volume and times is strictly implemented. Otherwise, the decoction made by frying looks "colorless", smells "odorless", and drinks "tasteless".

3   The determination of the material basis of the quality of traditional Chinese medicine and the basis for putting forward the quality marker (q-markers)  

3.1   Complexity of structural types of chemical constituents in traditional Chinese Medicine

Traditional Chinese medicine contains many kinds of chemical components, which are related to the effectiveness and safety of traditional Chinese medicine. When certain conditions are met, traditional Chinese medicine components can become quality markers (q-markers) reflecting the quality of traditional Chinese medicine. The secondary metabolites formed by biological or non biological factors of traditional Chinese medicine (medicinal plants) are the material basis of its active ingredients, the material basis of drug discovery and an important source of new drugs. Many secondary metabolites are derived from primary metabolites, and their structures have complex diversity. Common secondary metabolites include alkaloids, flavonoids, terpenoids, anthraquinones, coumarins and lignans. Moreover, different types of compounds have group specificity (such as families, genera, species, subspecies, varieties, etc.), and also have significant biological activities and medical uses.

3.2 the biosynthetic pathway (biogenic pathway) of chemical components of traditional Chinese medicine is the basis of chemical biology and phylogeny

As mentioned above, the common secondary metabolites alkaloids, flavonoids, terpenoids, anthraquinones, coumarins and lignans have different chemical structures. Moreover, different types of compounds have group differences (such as families, genera, species, subspecies, varieties, etc.) and form substructures of different skeletons, thus establishing the diversity of secondary metabolites in different plants under the influence of various factors (biological genetic factors, growth and development differentiation factors, environmental factors, etc.).

These compounds form compounds with ever-changing molecular structure in plants through complex formation processes and biosynthesis mechanisms such as acetic acid malonic acid pathway, isoprene pathway, shikimic acid pathway and amino acid pathway, and are endowed with different biological activities and therapeutic uses.

According to different structural characteristics, the main natural flavonoids can be divided into flavone, flavonol, flavanone, isoflavones, isoflavones, isoflavones, isoflavones, dihydrochalcone, orange ketone, xanthones, flavanes, flavanols, flavan-3,4-diols diols), anthocyanidins, biflavonoid, etc. In addition, some flavonoids have complex structures, forming alkaloid flavonoids such as banyan and isobanyan. The main flavonoids in traditional Chinese medicine have 11 basic skeleton structures. According to the basic characteristics of its structure, it is found that there are different types of skeleton structures, which are replaced by hydroxyl or sugar at different positions of the skeleton structure to form different flavonoids, which are distributed in different traditional Chinese medicine or medicinal plants. Quercetin is the most typical flavonoid. Many citrus fruits contain a lot of flavonoids, such as tangerine and nobiletin. Soybean contains a kind of isoflavone, soybean isoflavone. The tea polyphenols in tea are composed of gallic acid and flavonoids catechol.

There are many kinds of plant secondary metabolites in traditional Chinese medicine with complex functions. The amount of some compounds with specific structures varies greatly and is very low. Plant secondary metabolites are the products of plant biosynthesis. They are usually formed in specific tissues, organs or cells during the growth of traditional Chinese medicine. Plant secondary metabolites can closely relate the quality and quantity of secondary metabolites to the species, subspecies or varieties of medicinal plants from their biosynthetic pathways. According to the comprehensive study on the synthesis and accumulation of plant secondary metabolites, it is considered that the genuine (regional and geographical factors), individual, strain, age, sampling location, sampling period, sample storage time and other different factors of traditional Chinese medicine have an impact on the synthesis and accumulation of plant secondary metabolites. From the molecular level, the influence on the formation of chemical substances in traditional Chinese medicine can be reflected in the influence of plant internal factors in complex processes such as gene level, transcription level, different post transcription steps, different synthesis methods, etc.

Flavonoids are formed by the basic biosynthetic pathway of polyphenols, that is, a series of flavonoids are generated from phenylalanine tyrosine under the action of different enzymes（Figure 1）。

Figure 1  Biosynthetic pathway of polyphenols starting from phenylalanine tyrosine Fig. 1  Biosynthetic pathways of polyphenols from phenylalanine-tyrosine as a starting materials

 fromFigure 1Thus, chalcone synthase (CHS) catalyzes the first step of this pathway. Chalcone isomerase (chi) catalyzes intramolecular cyclization. Isoflavone synthase (IFS) catalyzes the synthesis of (2S）-Flavanone (5,7,4 '- trihydroxychalcone) or (2S）-The B-ring of 5-deoxyflavanone (7,4 '- dihydroxychalcone) was transferred from C-2 to C-3, and then the heterocyclic C-2 and 3 formed double bonds by isoflavone dehydratase. Flavanone-3 β -hydroxylase (F3H) catalyzes the synthesis of Chi   (2S）-Flavanone or (2S）-The C-3 position of 5-deoxyflavanone is hydroxylated to produce dihydroflavonol. Flavonol Synthase (FLS) catalyzes the hydroxylation of C-3 position in the flavonoid structure to form various flavonol substances. Dihydroflavonol-4-reductase (DFR) is a key enzyme in the synthesis of anthocyanidins and tannins, and it is an important branch point.

Flavonoids are widely found in medicinal plants, such as Ginkgo biloba, safflower, Scutellaria baicalensis Georgi, tangerine peel and so on. The structural diversity of flavonoids makes them have a wide range of pharmacological activities and therapeutic values, such as regulating blood lipids, expanding coronary arteries, hemostasis, antitussive, expectorant, reducing vascular fragility, antibacterial, liver protection, detoxification, treatment of acute and chronic hepatitis and liver cirrhosis. Through the research of biosynthesis pathway, the development of secondary metabolism engineering of medicinal plants can be promoted, which can provide technical support for improving the quality of traditional Chinese medicine, breeding of improved varieties, standardized planting and quality control.

Taking the biosynthesis of berberine as an example, tyrosine（L-At the beginning of tyrosine, dopamine is produced through tyramine. Then berberine is produced in two stages（Figure 2）. In the first stage of berberine synthesis, it occurs in the cytoplasm. Under the action of norcoclaurine synthase, dopamine and 4-hydroxyphenylacetaldehyde are condensed to form the benzylisoquinoline alkaloid norcoclaurine. Noraconitine receives the methyl group from adenosylmethionine and is converted to annonine by several methylation reactions. In the second stage, annonine was transported into the vesicles of the endoplasmic reticulum by special carriers, forming berberine bridges under the action of cyclization, and further forming the basic skeleton of protoberberine - scoulerine. Chrysophane Corydalis obtained methyl group from adenosylmethionine to form tetrahydrocollumbamine. Under the catalysis of hydrogenated berberine synthase, it formed methylene dioxygen ring structure and converted to hydrogenated berberine. The last step of berberine synthesis is catalyzed by tetrahydroberberine oxidase, using hydrogenated berberine as substrate for oxidative dehydrogenation, and finally forming berberine.

Figure 2  Tyrosine initiated biosynthesis and regulation of alkaloids Fig. 2  Biosynthesis and regulation pathway of alkaloids starting with tyrosine

During the biosynthesis of tyrosine based alkaloids, several intermediate products, noraconitine, were formed in Aconitum japonicumAconitum japonicum  Thunb.、 Lotus seedNelumbo unciferaGaertn、 Komatsu KOMATSUGnetum parvifolium  (warb.) C. y. Cheng ex Chun; Annotatine exists in Annonaceae plant Litchi chinensisAnnona reticulata  L.、 Annona chinensisAnnona squamosaL.、 Lotus seed and lotus leafFolium Nelumbinis, Magnolia officinalisMagnolia officinalis  Rehd. et Wils; Golden Violine is found in Eupatorium adenophorum LGueldenstaedtia multiflora  Bunge and other plants; Tetrahydrotetrandrine existed in tetrandrine palmatum and Rhizoma Coptidis; Hydrogenated berberine in Coptis chinensisCoptis chinensis  Franch.、 Phellodendron amurensePhellodendron amurense  Rupr.、 Three needlesBerberis pruinosa  Franch. et al. Berberine and coptisine are alkaloids from Coptis chinensis, sanguinarine is mainly found in ChelidoniumChelidonium majus  L.、 CorydalisCorydalis mucronifera  Maxim.、 Bola gyrusMacleaya cordata  (Willd.) R. Br.、 Blood water herbEomecon chionantha  Alkaloids in Hance. Although berberine, jatrorrhizine and palmatine are contained in both phellodendron and Coptis chinensis, coptidine is a unique organism of Coptis chinensis and phellodendrine is a unique alkaloid of Phellodendron chinensis. Therefore, the origin of alkaloids can be distinguished from these differences.

4   Basic concept of q-marker of traditional Chinese medicine and its significance in quality evaluation 4.1 background of q-marker of traditional Chinese Medicine

The research on the quality of traditional Chinese medicine and the establishment of quality standards is a complex systematic project. There are different methods and opinions on how to study and formulate standards. At present, the quality standards of the system recognized by the industry are under research or dispute. In Chinese Pharmacopoeia, there are many ways to evaluate the advantages and disadvantages of traditional Chinese medicine according to the quantity of one or several index components, but the clinical efficacy of traditional Chinese medicine is not necessarily the function of one or several components. At present, the establishment of evaluation standards for traditional Chinese medicine is the basic starting point for establishing the quality standards for the authenticity, advantages and disadvantages of traditional Chinese medicine. This is directly related to the identification and determination of the origin. Establishing qualitative and quantitative detection methods to obtain multiple characteristic component analysis methods and fingerprints to make them specific and controllable is the basis of quality standards. Considering the complexity of traditional Chinese medicine theory, prescription, preparation, dosage form and usage, this paper puts forward the concept of q-marker of traditional Chinese medicine, which lays a foundation for standardizing the quality research and standard establishment of traditional Chinese medicine. In order to overcome the shortcomings of the existing quality standards, improve the consistency, controllability and new source of quality, which is conducive to the production process control and quality supervision of traditional Chinese medicine products.

4.2   Definition of q-marker of traditional Chinese Medicine

Traditional Chinese medicine q-marker is a chemical substance that is inherent in traditional Chinese medicine and traditional Chinese medicine products (such as traditional Chinese medicine slices, traditional Chinese medicine decoctions, traditional Chinese medicine extracts, and traditional Chinese patent medicine preparations) or formed during processing and preparation and is closely related to the functional properties of traditional Chinese medicine. It is used as a marker to reflect the safety and effectiveness of traditional Chinese medicine for quality control. Instead of the chemical substances absorbed and produced by them through the process in the organism (such as metabolites in the human body, digestive enzymes or chemical substances transformed by microorganisms), their chemical structures need to be determined through structural analysis, and the specific chemical components can be qualitative and quantitative.

Basic conditions of q-marker: (1) chemical substances inherent in Chinese medicinal materials and products or formed during processing and preparation; (2) It is closely related to the functional properties of traditional Chinese medicine and has a clear chemical structure; (3) Substances that can be qualitatively identified and quantitatively determined; (4) According to the principle of the first choice of prescription and monarch medicine composed of compatibility of traditional Chinese medicine, taking into account the representative substances of minister and assistant medicine.

4.3   Factors influencing q-marker of traditional Chinese medicine  

4.3.1   Cell and tissue specificity of biosynthesis

There are a large number of metabolic enzymes and substrates related to the synthesis of secondary metabolites in plant cells and tissues. These enzymes and substrates complete the synthesis of secondary metabolites in different cells and organs. For example, the higher amount of pyrrolidine alkaloids in the stem bark of Senecio scandens is related to the high distribution of outer epidermal cells; Another example is that the hyoscyam alkaloids in hyoscyam are transported to the aboveground part after the epoxidation of tianxianzimine in the middle column of the root. These specific chemicals as q-marker are related to the parts used by plants.

4.3.2     Organ specificity of biosynthesis

Plant organs are composed of cell tissues. Specific secondary metabolites are synthesized and accumulated in the cell tissues of specific organs, and the types and quantities of substances synthesized are also different due to the differences of their enzymes. For example, artemisinin is formed and accumulated in the glandular hairs of Artemisia annua; Another example is that vinblastine and vincristine of Catharanthus roseus are specifically distributed in leaves and stems.

4.3.3   Developmental specificity of biosynthesis

During plant development, the accumulation of secondary metabolite synthesis leads to cell differentiation and the formation of plant organs, and then secondary metabolites are accumulated in their organs. In this process, synthetases in plant organs regulate gene and protein levels and limit the production of secondary metabolites.

4.3.4   External factors in the growth process of traditional Chinese Medicine

From the perspective of genetics, the genetic essence of genuine medicinal materials is usually a quantitative change process at the population level. The difference between genuine medicinal materials and other non genuine medicinal materials in the species is mainly the change of genotype frequency in the population. It is important to show that polygenes control the interaction between genetic factors and environment at the individual level, which affects the production of secondary metabolites. Many aspects of plant life activities, such as physiological regulation, self-protection, survival competition, coordination and environmental relations, play an important role in the synthesis of secondary metabolites. Moreover, various external factors such as ecological environment, such as light, temperature, soil, water, air and biological and microbial factors, all affect the secondary metabolism of medicinal plants.

Houya et al. Analyzed the impact of ecological environmental factors on the synthesis and accumulation of secondary metabolites in medicinal plants, and expounded the application of plant ecology, functional genomics, proteomics, metabonomics and systems biology methods in the study of secondary metabolites in medicinal plants. It is pointed out that the systematic study of the comprehensive action of multiple ecological factors, the systematic integration of multiple omics technologies, the in-depth study of the biosynthetic pathway, metabolic law and key regulation mechanism of secondary metabolites of medicinal plants, and the production of active components of medicinal plants through metabolism are conducive to the construction of high-quality medicinal material production base. Tanyouli and others believe that climate is the main ecological factor that determines the water and heat site conditions for plants to survive. With the impact of global warming on the growth, metabolism and reproduction of medicinal plants, the changes of secondary metabolites of medicinal plants are considered₂The increase of greenhouse gases caused climate warming, and high temperature affected the growth of medicinal plants and the accumulation of effective components. Jiaoxiaolin et al. Confirmed that triterpenoid saponins are a kind of plant secondary metabolites with multiple biological and pharmacological activities by studying the influence of environment on the biosynthesis of triterpenoid saponins in plants, as well as the biosynthesis pathway and key enzymes of triterpenoid saponins. In addition to genetic factors, light, temperature, water, salt, soil conditions and other factors in the environment affect the synthesis of triterpenoid saponins in medicinal plants.

4.3.5   Factors of traditional Chinese medicine standard decoction or traditional Chinese patent medicine preparation

With the development of traditional Chinese medicine industry and clinical use of traditional Chinese medicine, various forms such as decoction pieces, refined decoction pieces, granule decoction pieces, broken wall decoction pieces and formula granules have emerged. The standard decoction of decoction pieces of traditional Chinese medicine is a liquid preparation based on the theory of traditional Chinese medicine and clinical application, with reference to modern extraction methods. After Decoction of decoction pieces, it is properly concentrated. It can adapt to the current characteristics of clinical medication, standardize different forms of clinical medication, and meet the needs of clinical medication. As the standard decoction of decoction pieces of traditional Chinese medicine is a direct clinical form of taking. The standard decoction should reflect the influence of the extraction process, without the interference of excipients, and can be prepared into the required dose. The standard decoction of decoction pieces of traditional Chinese medicine follows the decocting principle of traditional decoction. Its preparation process has the characteristics of standardization, standardization and individualization, which can ensure the unity of process and the stability of quality.

As for the Chinese patent medicine industry, due to the addition of many modern industrial elements and technologies in its process, many products are not prepared based on decoction. For example, a certain solid dosage form or a variety of dosage forms (such as tablets or capsules) are made from the powder of the whole herbal medicine, or a certain solid dosage form or a variety of dosage forms are made from the pre concentration of some herbal medicines and the powder of some herbal medicines, or a certain solid dosage form or a variety of dosage forms are made from the concentration of water extraction and alcohol precipitation, or a certain solid dosage form or a variety of dosage forms are made from the extracted parts. There are also normative factors of processing methods. Therefore, due to different sources of pharmaceutical raw materials, different processes and different dosage forms, the number and quantity of active substances in the preparations fluctuate greatly, which increases the complexity of establishing quality standards and controlling quality, and makes it more difficult to judge the substitutability of different dosage forms of Chinese patent medicines with the same name in clinical use. Therefore, it is necessary to carry out quality controllability research according to the actual situation of different preparations in order to accurately establish the fingerprint of samples, identify q-marker and determine the upper and lower limits of their quantification.

4.4   Determination and research methods of q-marker of traditional Chinese Medicine

Q-marker of traditional Chinese medicine is a marker of the quality of traditional Chinese medicine, which must be closely related to the effectiveness of traditional Chinese medicine. Standard decoction of decoction pieces of traditional Chinese medicine is the basic standard form of clinical application of traditional Chinese medicine and the core link of tracing the effectiveness of traditional Chinese medicine. According to the definition of q-marker of traditional Chinese medicine, it is proposed to take the standard decoction of decoction pieces of traditional Chinese medicine as the core sample for quality research, determine the q-marker of traditional Chinese medicine, trace the source to the medicinal materials and decoction pieces (and processed products), and extend to the compound preparations and Chinese patent medicines. This paper presents the following research process of q-marker of traditional Chinese medicine for standard decoction of decoction pieces of traditional Chinese medicine.

4.4.1   Samples shall be sufficiently representative

According to the relevant requirements of Chinese pharmacopoeia for the study of medicinal materials and decoction pieces, the identification of samples should be determined to species, and the combination of traditional identification and DNA bar code identification is recommended.

4.4.2   Processing of decoction pieces

It is processed according to the relevant provisions of Chinese Pharmacopoeia (2015 Edition), or according to the local processing methods in the real estate or main production areas.

4.4.3   Quality inspection of decoction pieces before decocting

The content, appearance, detection, moisture content, etc. of the prepared pieces shall be tested according to the relevant provisions of Chinese Pharmacopoeia.

4.4.4   Sample dosage

The recommended dosage of decoction pieces is 100g for the preparation of standard decoction. The samples should be no less than 10 batches to avoid systematic error caused by too few samples.

4.4.5   Solvent and solvent dosage

According to clinical decocting, purified water is commonly used. Decoct with traditional prescription. However, the amount of water added is random and different, which needs to be further refined. The amount of water added for decocting and the amount of decocting liquid can be calculated as 6 ~ 8 times of the amount of decoction pieces.

4.4.6   Soaking and decocting time and times

Soaking the medicinal materials before decocting is beneficial to the dissolution of ingredients. It is recommended that the soaking time be 30 min. Each decoction piece is recommended to be decocted twice. For general drugs, the first decocting time is 30 minutes and the second decocting time is 20 minutes. The decocting time can also be prolonged or shortened according to specific requirements.

4.4.7   Concentration method

It is recommended to use reduced pressure concentration. The concentration temperature is recommended not to exceed 50 ℃. Considering the needs of quality control, it is recommended to concentrate the volume to 5 times the quality of the medicinal materials. The concentrated solution shall be frozen and kept away from light.

4.4.8   Establishment of fingerprint of standard decoction of decoction pieces of traditional Chinese Medicine

It is suggested to establish the fingerprint of the standard decoction of traditional Chinese medicine by liquid (gas) phase or liquid (gas) mass spectrometry, identify the number and chemical structure of the chemical substances in the fingerprint, select the specific substance related to the activity (efficacy and safety) of the decoction as q-marker, and compare it with the standard reference drug or reference substance for quality control.

4.4.9   Quantitative method of reference materials

It is generally recommended to use HPLC, GC, LC-MS and GC-MS for the quantification of q-marker. Wangzhimin's research group has established and published articles on "one test and multiple evaluation method" (QAMs), and has completed the determination of the effective components of medicinal materials and preparations. These quantitative analysis methods, which have been recognized by Chinese pharmacoeia, can be used as the quantitative methods of q-marker.

In order to identify the differences between different manufacturers and different dosage forms, it is necessary to prepare the standard extract and obtain the standard fingerprint; Identify and determine the structure of possible chemical substances, determine whether they are related to biological activity, and select q-marker; Determine the q-marker for quantitative determination in the existing chemical substances according to the needs; Compare the quantity difference of q-marker between batches of the same dosage form products of the enterprise to determine the upper and lower limits; Compare the quantity difference of q-marker of different dosage forms among different enterprises, and draw a conclusion whether it is equivalent according to the analysis results. The key steps of the research process are shown inFigure 3。

Figure 3  Key steps in q-marker research of traditional Chinese Medicine  Fig. 3  Key steps of research on Q-marker in Chinese materia medica

4.5   Determination principle of q-marker of traditional Chinese Medicine

（1）Q-marker of traditional Chinese medicine is a quality marker related to efficacy, which exists in traditional Chinese medicine, decoction pieces, extracts, single or compound preparations. After research and analysis, it is determined that such substances have biological specificity. Therefore, its q-marker is a chemical substance that reflects the quality of traditional Chinese medicine, decoction pieces, single or compound preparations.

（2）In q-marker research, samples must be prepared by standard methods (standard extracts of single or compound traditional Chinese medicine preparations or standard extracts of whole medicinal materials prepared according to the standard decoction or standard process for clinical application of traditional Chinese Medicine) to confirm the qualitative and quantitative q-marker.

（3）In order to ensure the traceability of q-marker, the quality marker of the preparation should be determined on the basis of the q-marker of the medicinal materials, decoction pieces or extracts.

（4）In order to reflect the principle of prescription compatibility of traditional Chinese medicine preparations under the guidance of traditional Chinese medicine theory, the determined preparation q-marker should pay attention to the principle of "giving priority to monarch medicine, giving consideration to minister, assistant and envoy" with the characteristics of prescription compatibility.

Through the above normative research, a quality management system of traditional Chinese medicine based on q-marker has been formed（Figure 4）。

Figure 4   Quality management system of traditional Chinese medicine based on q-marker  Fig. 4  Quality management system on basis of Q-marker in Chinese materia medica

5   Research examples  

5.1   Q-marker of Compound Danshen preparation

Compound salvia miltiorrhiza preparation is a compound preparation composed of Salvia miltiorrhiza, Panax notoginseng and borneol. Chinese Pharmacopoeia contains seven dosage forms of this variety, which is a large variety with large sales and many manufacturers in China.

It was identified that salvianolic acid and tanshinone were the main active components in Radix Salviae Miltiorrhizae. Salvianolic acids include salvianolic acid A, B, D, Danshensu (DSU), caffeic acid, cinnamic acid, ferulic acid, protocatechuicaldehyde, rosmarinic acid (RA), lithospermic acid B (LB). Tanshinones include tanshinone, dihydrotanshinone Ⅰ (dt- Ⅰ), tanshinone Ⅰ (t- Ⅰ), tanshinone Ⅱ_A（tanshinone Ⅱ_A，T-Ⅱ_A）, tanshinone Ⅱ_B（tanshinone Ⅱ_B，T-Ⅱ_B）Cryptotanshinone (CT). See for the chemical fingerprint of Salvia miltiorrhiza BgeFigure 5, the same chemical fingerprints of Salvia miltiorrhiza can be obtained by HPLC and LC-MS.

Figure 5    Chemical fingerprints of Radix Salviae Miltiorrhizae  Fig. 5   Fingerprints of Salvia miltiorrhiza

Panax notoginseng contains a large number of chemical substances, mainly saponins, flavonoids, volatile oil, amino acids, polysaccharides, starch, protein and some inorganic elements such as nitrogen, phosphorus, potassium, cobalt, molybdenum, cesium, etc. So far, 54 monomeric saponins have been isolated from different parts of Panax notoginseng, such as ginsenoside ra₃、Rb₁、Rd、Re、Rg₁And Notoginsenoside R₁、 G. Most of these monomeric saponins are damarane type 20（S）-Protopanaxadiol type and 20（S）-Protopanaxatriol type. The underground part of Sanqi has 20（S）-Protopanaxadiol saponin, also containing 20（S）-Protopanaxatriol saponins. The aboveground part of Panax notoginseng takes 20（S）-Protopanaxadiol saponin is the main type. Flavonoids include Panax notoginseng flavone A and Panax notoginseng flavone B.

In Compound Danshen tablets, the water-soluble components of Danshen, salvianolic acid B, tanshinol, protocatechuic aldehyde, protocatechuic acid and fat soluble component tanshinone Ⅱ, are generally determined for Danshen_ACryptotanshinone and tanshinone I. According to the fingerprints reported in the literature, the main component of Panax notoginseng is Panax Notoginsenoside R₁And ginsenoside Rg₁、Rb₁Therefore, the q-marker for qualitative identification of Compound Danshen tablets was identified as tanshinol, salvianolic acid B and tanshinone Ⅱ_A, cryptotanshinone, tanshinone Ⅰ, Notoginsenoside R₁, Panax Notoginsenoside g, ginsenoside Rg₁Ginsenoside Rb₁  9 chemical components. HPLC or LC-MS is recommended for the determination of tanshinol, salvianolic acid B and tanshinone Ⅱ_AAnd Notoginsenoside R₁So as to control the quality of the effective components of Compound Danshen tablets.

5.2     Q-marker for processing traditional Chinese Medicine

Taking nux vomica as an example, the determination process of the markers was analyzed. Nux vomica is usually processed and used as medicine. The unprocessed strychnine contains more than 14 alkaloids, which can be divided into three types: (1) normal series alkaloids: strychnine, Brucine, isostrychnine, isobrucine, and strychnineN-Oxide (strychnine N-oxide）、 BrucineN-Oxide (brucine N-Oxide), β - colubrine, 16 hydroxy - β - colubrine, 16 hydroxy - α - colubrine; (2) "Pseudo series" alkaloids: pseudo strychnine, pseudo brucine; (3)“N-Methyl pseudo "series（N-Methylpseudoseries) alkaloids:N-Methyl broken pseudo muscovine, muscovineN-Methyl break pseudobrucine.

The prescription of Biqi Capsule comes from the prescription "yixiandan" handed down by Hua Tuo, a famous doctor of the Han Dynasty. It is a representative prescription for the treatment of common rheumatic diseases, arthritis and other chronic diseases. Its clinical efficacy is accurate. This compound prescription is a famous prescription of various herbs of monarch, minister, assistant and envoy. In this prescription, the monarch drug nux vomica is the prepared powder, dangshen, Atractylodes macrocephala, Poria cocos and Salvia miltiorrhiza are the minister drugs, Panax notoginseng, Ligusticum chuanxiong, Achyranthes bidentata and earthworm are the adjuvants, and the agent licorice is used to blend all the drugs, which fully reflects the principle of "monarch, minister, assistant and envoy" compatibility of traditional Chinese medicine. The pharmacodynamic study revealed the mechanism of increasing efficiency and reducing toxicity of Biqi capsules, which provided a reliable scientific basis for rational clinical application.

The pharmacokinetic study of Biqi Capsule in terms of its disassembled formula and compatibility showed that both the minister drug group and the adjuvant drug group could significantly prolong the peak time of strychnine and Brucine, delay the absorption, and avoid the toxic and side effects caused by too fast absorption. There was no significant pharmacokinetic difference between the single drug group of minister and adjuvant drugs and the monarch drug（Figure 6、7）. This study revealed the influence of the interaction of minister, assistant and agent on the pharmacokinetics of Junyao, reflecting the scientificity of the compound compatibility of Biqi capsules.

Figure 6  Effect of minister, assistant and envoy drugs on blood concentration of strychnine Fig. 6  Effect of minister, adjuvant, and guide medicines on blood concentration of strychnine in king medicine

Figure 7    Effect of minister, assistant and envoy on brucine concentration in plasma  Fig. 7   Effect of minister, adjuvant, and guide medicines on blood concentration of brucine in king medicine

    In Biqi capsules, Strychnos nux vomica is prepared and used. The main alkaloids after processing are strychnine and strychnine（Figure 8）, the amount of other alkaloids has been significantly reduced. Moreover, the amount of brucine and strychnine can be controlled to the required level after being prepared with auxiliary materials. Therefore, when formulating the quality standard of the product, the quantity of the two alkaloids of Junyao was determined as the quantitative determination index. In this study, the amount of these two alkaloids in Biqi Capsule is a quantitative measurement index, which is not only a q-marker, but also a pharmacokinetic marker (PK marker), but also an important effective component of the efficacy.

Figure 8  Chemical structures of brucine (a) and strychnine (b) Fig. 8 Structures of brucine (A) and strychnine(B)

6   Discussion  

6.1   Improving the quality standard system with Chinese Pharmacopoeia as the core is the basis for improving the quality of traditional Chinese Medicine

The construction of a quality standard system with Chinese Pharmacopoeia as the core is the basis for the quality research of traditional Chinese medicine and the formulation of national quality standards. It is a major issue that should be paid attention to at the national level. According to the statistics of the food and drug administration, more than 90% of the unqualified products due to quality problems in the first three months of this year are traditional Chinese medicine. The quality of traditional Chinese medicine should be paid attention to. What's more, it is found from the published papers that a variety of chemical synthetic drugs are added to Chinese patent medicines. For example, metformin, phenformin, glipizide, glibenclamide, pioglitazone or rosiglitazone are illegally added to the traditional Chinese medicine capsules for the treatment of diabetes. Among them, a hypoglycemic traditional Chinese medicine capsule was found. 2.6 mg of phenformin and 2.0 mg of glibenclamide were added to each capsule. As academician hanqide said recently, "the current quality of traditional Chinese medicine is very worrying and has become one of the bottlenecks in the development of traditional Chinese medicine". He also pointed out that "to solve this problem, we can't do it overnight. We need comprehensive research, but we can start from strengthening supervision. Whether it's natural herbal medicines or Chinese patent medicines, their quality should be tested by a third party. Strengthening third-party supervision is the direction of reform".

According to the content of the 2015 edition of Chinese Pharmacopoeia, the content, standard and scientificity are much better than those of previous editions. However, Chinese pharmacopoeia is a code for drug quality management and an open law enforcement standard. Therefore, problems such as naming, prescription composition and dosage, test items and content determination, component selection of monarch and Minister adjuvants, quality comparability and substitutability of different preparations of compound products of the same name, and the new source from raw materials to finished products in the quality standards of prescription Chinese medicine must be standardized.

Traditional Chinese medicine is a part of traditional Chinese medicine. Its variety development is closely related to the prescription and preparation method under the guidance of traditional Chinese medicine theory. However, as a drug, its quality standard must comply with relevant laws and regulations in order to become a safe, effective and quality controllable product. In the document on promoting the healthy development of the pharmaceutical industry issued by the State Council on march4,2016, it was proposed to "improve the quality standard system, improve the national drug standard system with Chinese pharmacoeia as the core, implement the action plan for improving the standards of drugs and medical devices, promote the upgrading of the quality standards of essential drugs, high-risk drugs, pharmaceutical excipients, packaging materials and basic, universal and high-risk medical devices, improve the technical specifications and quality control standards for the production of traditional Chinese medicine and ethnic medicine, improve the scientificity, rationality and operability of the standards, and strengthen the authority and seriousness of the standards". It further realized the core position of Chinese pharmacopoeia in the construction of quality standard system, and made clear the importance of the core position of Chinese pharmacopoeia in the relationship among the food and drug administration, drug audit and drug inspection. The food and drug administration is the superstructure of the three leading parties. The review and quality inspection of drug examination and drug inspection must comply with the legal requirements of Chinese Pharmacopoeia（Figure 9）In order to facilitate the construction of a national drug standard system with Chinese Pharmacopoeia as the core.

Figure 9  National drug standard system with Chinese Pharmacopoeia as the core Fig. 9  National drug standards system of Chinese Pharmacopoeia as core

6.2   About markers

Marker is a "hot word". "Biomarkers" related to drugs and treatment are biological or biochemical indicators that mark changes or possible changes in the structure or function of systems, organs, tissues, cells and sub cells. They have a very wide range of applications. Biomarkers can be used for disease diagnosis, disease staging, or to evaluate the safety and effectiveness of new drugs or therapies in the target population. Genetic markers have no biological function, and their variation (DNA sequence or structure change) has no pathogenic effect. However, genes are functional, and changes in their sequence or structure often lead to functional changes and diseases. Genetic markers are often used in molecular diagnosis to mark the genomic region near an important oncogene and track whether the oncogene or tumor cell is inherited in the family and whether the gene is lost. Plant marker, also known as plant bio marker, is a secondary metabolite formed by plants during their life cycle. Its research is to find substances that represent species characteristics in the process of plant development, differentiation and growth. The q-marker of traditional Chinese medicine is derived from this. Because its research is based on the chemical nature of secondary metabolites, it can also be called quality chemical marker (q-chem- marker), which is used to find the relationship between the specific secondary metabolites of a traditional Chinese medicine and their species, and to determine the markers representing the characteristics of a traditional Chinese medicine, as well as the efficacy and medical use of related substances.

In order to improve the quality of traditional Chinese medicine, domestic researchers have put forward the concept of q-marker. For example, q-bio-marker is a bioactive indicator that can directly or indirectly reflect the clinical efficacy or pharmacological action of traditional Chinese medicine products, including bioactivity value or potency, biomarker, biological fingerprint, etc. Biological potency can better reflect the overall activity or efficacy of traditional Chinese medicine products, especially for traditional Chinese medicine products whose chemical basis is not clear and whose quality is difficult to be evaluated by conventional physical and chemical methods. Biological effect expression profile can not only evaluate the quality of traditional Chinese medicine, but also be used to identify the authenticity or quality fluctuation of traditional Chinese medicine due to its fingerprint or characteristics. Q-holistic marker (q-holistic marker) is a quality evaluation index formed by synthesizing and quantifying multiple indexes related to the internal quality of traditional Chinese medicine, such as genuine quality index, effective component index, effect equivalent, etc. The biomarkers based on metabonomics have strong quality differentiation ability to evaluate the quality of traditional Chinese medicine. The comprehensive quality markers of traditional Chinese medicine have the advantages of integrity, systematicness and quantification, and have advantages in the comprehensive quality evaluation of traditional Chinese medicine.

6.3   Differences between q-marker and effective components of traditional Chinese Medicine

Pharmacodynamic substances (active ingredients) of traditional Chinese medicine can not only exert their efficacy in prototype form, but also in the form of one to several (or many) metabolites, or both. Therefore, all the material forms that may directly exert efficacy in the body are called "effective forms", and then the hypothesis of "superposition effect" of effective forms on a target is put forward, in order to prove the "effective forms" and the mechanism of "superposition effect" of the effective substances of traditional Chinese medicine through systematic research. The superposition of multi-component or / and multi metabolites on each target, coupled with the multi-component synergy between each target, together constitute the important connotation of the pharmacological action mechanism of traditional Chinese medicine. The clarification of the "effective form" and its action mechanism (superposition and synergy) of the effective substances of traditional Chinese medicine will provide a scientific basis for the effectiveness of traditional Chinese medicine. Q-marker of traditional Chinese medicine is an inherent chemical substance in pharmaceutical preparations. It does not analyze the complex process of these substances in vivo, and does not consider the contribution of various components and metabolites to quality control.

6.4   Differences between q-marker and PK marker of traditional Chinese Medicine

According to the concept of PK marker, it is considered that the chemical components or their metabolites in traditional Chinese medicine preparations exist in body fluid or tissue or excreta in the form of prototype or metabolite in the body, and can transport and determine their change with time in the body. These substances are called PK markers. Chinese scholars put forward that PK markers of traditional Chinese medicine are mainly used to reflect the substance exposure and influencing factors of traditional Chinese medicine after administration. Attaching importance to the research on the material basis of traditional Chinese medicine and putting forward new research ideas are more conducive to the research and development of new traditional Chinese medicine. Traditional Chinese medicine is a complex system. It is of positive scientific significance to use different types of markers to reflect the exposure, quality, efficacy and safety of substances in the body. These substances with appropriate pharmacokinetic (PK) properties are related to the drug effect, or to the drug effect at the target and maintain a certain concentration. For compound salvia miltiorrhiza preparation, its q-marker should be an inherent substance objectively existing in the preparation and related to biological activity, regardless of the existence of metabolites in the body and the relationship with activity and action mechanism.

6.5   The significance of the proposal of q-marker of traditional Chinese medicine to the construction of standardization of traditional Chinese medicine  

6.5.1   The proposal of q-marker of traditional Chinese medicine is closely related to the effectiveness of traditional Chinese Medicine - material base - quality control landmark components

For a long time, the quality control means, quality evaluation indicators and quality standards of traditional Chinese medicine are not strongly related to the effectiveness of traditional Chinese medicine. They lack the command of the core quality concept that can reflect the effectiveness of traditional Chinese medicine. There is a tendency of fragmentation in the quality research of traditional Chinese medicine, decoction pieces and proprietary Chinese medicine. The concept of q-marker of traditional Chinese medicine is proposed. According to the characteristics of its own pharmaceutical system, such as the biological properties, manufacturing process and compatibility theory of traditional Chinese medicine, it integrates multi-disciplinary knowledge and puts forward the concept of core quality, so as to guide the quality research of traditional Chinese medicine and further close the correlation between the effectiveness of traditional Chinese Medicine - material base - quality control landmark components.

6.5.2   The proposal of q-marker of traditional Chinese medicine is conducive to the establishment of the whole process quality control and quality traceability system of traditional Chinese Medicine

Q-marker of traditional Chinese medicine originates from the biosynthesis in the original organism of traditional Chinese medicine. It goes through the material transfer and chemical changes in the process of harvesting, processing, processing and pharmaceutical technology, and finally exerts its clinical efficacy in the form of compound preparation through the drug transfer process. It takes the material function as the core throughout the whole process of the formation and production of traditional Chinese medicine. Taking the standard decoction of decoction pieces of traditional Chinese medicine as the core model of the study, the quality research was carried out to determine the q-marker, trace the source to the medicinal materials and decoction pieces (and processed products), and extend to the compound preparations and Chinese patent medicines. The established thinking mode and research method focus on the uniqueness, difference, dynamic change of the material base in the whole process and the transmissibility and traceability of quality, which is conducive to the establishment of the whole process quality control and quality traceability system of traditional Chinese medicine.

This article is extracted from:Liuchangxiao, chenshilin, Xiao Xiaohe, zhangtiejun, houwenbin, liaomaoliang Quality marker of traditional Chinese medicine (q-marker): a new concept of quality control of traditional Chinese medicine products [j]. Chinese herbal medicine, 2016, 47 (9): 1443-1457