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Mongolian medicine: History, development and existing problems

Mongolian medicine (MM) is an important part of Mongolian culture. Exploration of MM can play a crucial role in the prevention and treatment of various diseases and can help provide better health care globally. In this article, we gave a brief introduction to the origin and development of MM, the theoretical system of MM, the principles of Mongolian materia medica formula, the modern research on Mongolian materia medica and the quality control of Mongolian materia medica. The present situation and outlook of MM were also discussed.


Introduction
Mongolian medicine (MM) is an integral part of Mongolian culture. During the long run of nomadic life, MM had increasingly integrated traditional Chinese medicine (TCM), Tibetan medicine, ancient Indian medicine, and other traditional medical theories and developed overtime. Theoretical systems of MM were formed to guide diagnosis, treatment, and medication. In the development of MM, drugs are closely associated with medicine, and an excellent doctor is always an expert in drugs. Therefore, MM is a concept of both medicine and drugs. As an important part of Mongolian culture, MM has become an irreplaceable part of the world medicine as well as Chinese medicine.
Mongolian materia medica is used for describing drugs used in MM and usually originates from natural materials, such as animals, plants, and minerals with less toxic side effect. Based on relevant literature statistics, there are more than 2200 items of Mongolian materia medica, of which about 450 are commonly used, including 313 plant drugs, 66 animal drugs, 48 mineral drugs and 23 others (Nuendagula, 2009). In ancient times, Mongolian people used a single medicine to treat diseases. In long-term practices, they summarized the drug theory of six flavors (six flavors refer to sweet, sour, salty, pungent, bitter and astringent), eight properties (eight properties refer to heavy, greasy, cold, blunt, light, coarse, hot and sharp. Flavors and properties are used for describing natures of medicines), seventeen effects (seventeen effects refer to soft, heavy, warm, greasy, solid, cold, blunt, cool, mild, dry, watery, thin, hot, light, sharp, coarse, and active and describe the effects of different medicines), and two powers which effectively guided the use of Mongolian materia medica. Even though the eight properties seem to be included in the seventeen effects, in fact, the eight properties describe the properties or natures of medicines, but the seventeen effects are describing the effect on human bodies, so their connotations are different. Base on the principle of origin, collection, effect, flavors after digestion and compatibility, the relevant drugs were prepared together and effectively played their drug functions, so MM prescription was formed and have been used by doctors of all generations for a long time. MM is still widely used in the modern clinic because its curative effect (Lan et al., 2018). Presently, more than 1500 traditional prescriptions of MM are available. Most of the prescriptions are mainly prepared in 10 traditional dosage forms, such as decoctions, powders, pills, ash mixtures and so on and the commonly used ones are powders and pills. A total of 260 of these prescriptions for treating six basic syndromes (Table 1) were selected as the classic prescription of MM (Liu, Hu, He, Jiang, & Xu, 2012 Li, & Songlin, 2009).
With the development of modern pharmaceutical sciences, researchers are putting their efforts into the extraction and isolation of active compounds, pharmacology research, formulation of quality standards and dosage form reform. The research on the chemical components of Mongolian materia medica has developed rapidly. Modern chromatographic separation techniques, spectral analysis and other technologies are used to determine the chemical components of Mongolian materia medica. Almost half of the prescriptions of MM contain Chebulae Fructus, which is also known as ''the king of Mongolian medicines" (Fig. 1D). Phenolic acids, tannins, triterpenoids, aliphatics, flavonoids, and volatile oils have been extracted and determined from Chebulae Fructus. In the pharmacological research of Mongolian materia medica, many modern pharmacological interpretations of traditional efficacy have been rasied. In MM, Chebulae Fructus is used to reduce the toxicity of Aconitum Kusnezoffii Radix. The compatibility of Chebulae Fructus and Aconitum Kusnezoffii Radix greatly reduces the content of toxic substances of aconitine, hypaconitine and mesaconitine from Aconitum Kusnezoffii Radix . The compatibility of Chebulae Fructus and Glycyrrhizae Radix et Rhizoma (Fig. 1A) with Aconitum Kusnezoffii Radix can up-regulate the expression of CYP450 enzyme to reduce the accumulation time of aconitine in the liver of normal rats (Huo et al., 2022). The research on the quality standard of Mongolian materia medica has developed gradually. In the past, traditional knowledge of medicines mainly relied on teaching by precept and example, but now, the state has issued many quality control standards. Some traditional Mongolian materia medica has been included in the Pharmacopoeia of the People's Republic of China with sufficient quality control methods. For example, the high-performance liquid chromatography (HPLC) method has been applied to determine the content of astragaloside IV in Astragali Radix (Fig. 1C), matrine and oxymatrine in Sophora Flavescenstis Radix and aconitine, hypaconitine and mesa- However, compared with TCM, MM is still in a weak position. The deficiencies can be summarized as insufficient in-depth research on the material basis of Mongolian materia medica, unsystematic research on the pharmacology, toxicology, and pharmacokinetics of Mongolian materia medica, unclear interpretation of the compatibility principles of Mongolian materia medica, and slow progress in the development of new Mongolian medicines.
In terms of quality control, after more than 30 years of scientific and technological development, the contents of active compounds need to be included in the standards. New technologies and methods should be used to formulate new standards of Mongolian materia medica.

Origin and development of Mongolian medicine
The origin and development of MM can be classified into the following four stages: The germination and experience accumulation stage before the 13th century, the theoretical formation stage between the 13th and 16th Century, the rapid development stage between the 16th and 20th Century, and the leaping development stage from the mid-20th Century to present (Menghe et al., 2021).
Before the 13th century, nomadic tribes that were scattered on the Mongolian plateau (northern part of today's China) started to accumulate their medicinal experiences and the theoretical knowledge began to sprout. A bloodletting therapy method from the nomadic tribes can be found in the Book of Han (Fig. 2B, Han is one of the dynasties in China from 202 BC to 220 AD and the Book of Han is a set of biographical history books mainly finished by Ban Gu (32À92 AD) in 105 AD, recording the stories of emperors and principal officials of Han,) and Xianbei (one of an ancient nationalities in northern China) was recorded to use moxibustion to cure diseases in the Records of the Three Kingdoms (Fig. 2C, the Three Kingdoms refer to Wei, Shu, Wu, three major kingdoms existing from 220 A.D. to 280 A.D. and the Records of the Three Kingdoms is a set of biographical history books written by Shou Chen (233À297 A.D.) from 280 A.D. to 290 A.D., recording the stories of emperors and principal officials of each kingdom). In the famous work of Qianjin Yaofang (Fig. 2D, the book means valuable prescriptions and is a classic work of TCM written in around 652 A.D. by a great doctor called Simiao Sun), Xiongnu Lusu Pill, a medicine named after an ancient ethnic group Xiongnu (Xiongnu is also called Huns and distributed in northern China from 318 B.C. to nearly 300 A.D.) was included with the function of warming the body up. In the masterpiece of the Secret History of Mongols ( Fig. 2A, the book tells the history of the formation, development and growth of the Mongolian written in 13th-14th Century), the positive health effects of fermented milk from mare were recorded and nowadays, people also drink it for health purposes. All these experiences and knowledge set the foundation for the formation of the theoretical system of MM.
In the 13th century, all the nomadic tribes on the Mongolian plateau were united under the name of Mongols and the establishment of the Mongol Empire across Eurasia greatly promoted communications among different ethnicities. Strengthened cultural integration provided a foundation for the formation of theoretical system for MM. Just then, huge progress was made in MM. Ancient Mongolians galloped on the battlefield all year round and wounds like cataclasis could easily occur. This greatly promoted the advancement of bonesetting. Yinshan Zhengyao (Fig. 3, it means principles of correct diet) was written in 1330 by Husihui (He worked as imperial physician in charge of Emperors' diet from 1314 to 1329). It is the first complete monograph on nutrition and food hygiene in China. Cold and Heat Theory was also established on clinical experiences at that period. The theory demonstrated that all diseases can be divided into cold and heat. When treating cold disease, medicines with hot properties will be used and vice versa. The properties were further developed into six flavors, eight properties and seventeen effects with a deeper understanding of diseases and medicines.
From the 16th century, rapid progression can be seen in MM because of the introduction of Sibu Yidian (an encyclopedia of Tibetan medicine with four volumes written during the 8th Century, which included classification of diseases, physiology, pathology, diagnosis and treatment, and drug formulation) into Mongolia regions. During the late 17th Century, an Indian medicinal book, Astangahrdaya Samhita (Astangahrdaya Samhita is a set of Indian medicine books with six volumes and 120 chapters which included the development of human bodies, physiology, disease and treatment) was also been introduced into Mongolian regions. Foreign medical knowledge is gradually integrated into MM. A number of Mongolian medical experts emerged and many great Mongolian medical books were completed during this period (Tables 2 and  3, Fig. 4).
Since the middle of the 20th century, MM has entered the era of leaping development. The MM culture inheritance, personnel training, scientific research, discipline construction, platform construction and international cooperation have been booming.
Undergraduate education of MM began in 1958 and postgraduate education of MM then began in 1985. In recent years, the national medical industry has developed rapidly and has been highly valued by the state and governments. In November 2014, the $40 billion ''Silk Road Fund" invested by the Chinese government was established. The Inner Mongolia government has issued several policies to support and promote the development of MM and activate the potential of MM development. According to related policies, by 2020, people of Inner Mongolia autonomous region has already enjoyed MM and TCM services evenly. Under the support of the Belt and Road initiative and related policies, MM has been ushered in an opportunity for great development.

Theoretical system of Mongolian medicine
MM as an important part of Mongolian cultural heritage has been used for health care and playing an important role of Mongols. Theoretical systems of MM were formed to guide diagnosis, treatment, and medication. The basic theory of MM can be summarized as three roots, five elements, six flavors, eight properties and seventeen effects, two powers (Ao, 2019).

Three roots or three essences
MM developed its special core basic theory called the three roots (or three essences) which refers to Heyi, Xila and Badagan. The three roots are not only the main material basis of human body, but also the important energy and power of human life activities. Heyi reflects the intrinsic motivation for the human body's breathing, blood circulation, metabolic function, mental and physical activities and all life movement. It has the features of light,  coarse, active, cool, tiny, and firm. Xila is mainly distributed in the human liver, gallbladder, and blood and is the source of body temperature, with the functions of regulating body temperature, promoting digestion, increasing appetite. It has the features of hot, sharp, greasy, light, smelly, fluid, and wet. Badagan means viscous liquid which makes the body strong and improves the memory of human-beings. It has the features of greasy, cold, heavy, slow, soft, hard, and sticky. The three roots come from parents and can be acquired by diets, daily lives, and other factors. The loss of three roots during human's physiological activities needs to be replenished in order to maintain their relative balance. Due to the different conditions encountered by each person in the process of growth and development, their Heyi, Xila and Badagan are different but they achieve a relatively stable equilibrium state with dif-ferent proportions in human bodies. When the equilibrium is disrupted by diet or some factors, Heyi, Xila and Badagan have the possibility of excessive increase or loss, resulting in loss of coordination and in turn, become pathological (Heyi, Xila and Badagan syndromes, Table 1). During treatment, we need to adjust the three roots, restore their original relative balance and make the lives get normal.

Five elements
In MM, five elements refer to Earth, Water, Fire, Gas and Space. Earth sets the foundation for plant growth. Based on Earth, plants get nutrients for their growth. Water is the liquid medium for plant growth. Nutrients dissolve in Water and thus can be transported to

MiJue FangHai
Zhambalaquejidansenpurenlai 1829 Compilation of nearly 2000 prescriptions and introduction to the composition, taste, dosage, preparation method and the main therapeutic function of each prescription were introduced.
A relatively complete collection of Mongolian medicine prescriptions.

Luobsangchultem 18th Century
A comprehensive medical work mainly focusing on the clinical practice of Mongolian medicine that briefly describes Mongolian medicine, prescriptions, and therapeutics.
Widely spread across Russia, Mongolia and China and played an important role in promoting the development of medical and health systems in these countries.

ShanHu YanFang
Ixidansengwangjila 1868 Introduction to 99 diagnosis and treatment methods of common diseases in different departments.
Summary of the previous clinical experience of Mongolian medicine and enriches the treatment and prescriptions.

GuanZhe ZhiXi
Jigemuddanzengzhamsu 1888 Medicines are divided into 10 categories according to their properties and sources, and the pharmacological effects of 322 drugs are summarized and recorded.
Contributes to the medical and health undertakings of the people. different parts of the plant body. Fire is the energy for the maturation of plants. Sunshine and warm temperature can also provide external Fire. Gas is more like pressure and bears the ability of diffusion and motivation. It is the intrinsic power to push the transportation of Water and Fire to promote plant growth. Inside the plants, Space forms the channel in which Water carries nutrients to different parts in the plant body and for outside, it refers to the space for existence of everything. The production of medicine is closely associated with soil, water, sunshine, air, and other natural conditions. During the development of all kinds of medicines, all five elements participate differently to form different medicines in terms of flavors, properties and effects due to the different participation of the five elements.

Six flavors
In TCM, five flavors are raised to describe the flavor of medicines. Based on sweet, sour, salty, bitter and pungent in TCM, Mongolian medicine added astringent as the sixth flavor. They are generated by two elements which are abnormally strong during the formation of medicine. If Earth and Water are strong, the flavor is sweet, if Fire and Earth are strong, the flavor is sour, if Water and Fire are strong, the flavor is salty, if Water and Gas are strong, the flavor is bitter, if Fire and Gas are strong, the flavor is pungent and if Earth and Gas are strong, the flavor is astringent. The sweet medicine has the function of nourishing the body. The sour medicine can strengthen the spleen as well as the stomach and help digestion. The salty medicine can warm the spleen as well as the stomach and stimulate appetite. The bitter medicine has the effects of clearing heat and liver-detoxification. The pungent medicine can warm the body and invigorate the stomach. The astringent medicine can moisten the skin and cool the body. In terms of the comprehensive efficacy of pharmaceutical flavors, the sweet, sour, salty, and pungent flavors can suppress Heyi, the sweet, bitter, and astringent flavors can suppress Xila and induce Badagan, the sour, salty, and pungent flavors can suppress Badagan and induce Xila and the bitter and astringent flavors can induce Heyi. In addition, there are also ''three flavors" in MM. In MM, the original fla-vors of the medicine will change during the process of digestion by the human body. That is, the salty flavor becomes the sweet flavor, the pungent and astringent flavors become bitter, the sweet, bitter, and sour flavors are constant, so the final flavor is sweet, bitter and sour after the digestion of six flavors. Therefore, the ''three flavors" refers to the medicine flavors after digestion.

Eight properties
Eight properties describe the properties of medicines include heavy, greasy, cold, blunt, light, coarse, hot, and sharp. In MM, the heavy and greasy drugs are used for Heyi, namely treating trance, dizziness, tinnitus, insomnia, forgetfulness, lethargy and paralysis; the cold and blunt drugs are mainly used for Xila, namely treating fever, polydipsia, diarrhea, jaundice and liver and gallbladder diseases; the light, coarse, hot and sharp drugs are used for Badagan, namely treating the body coldness, psychosomatic heaviness, loss of appetite, indigestion, vomiting, diarrhea, waist and knee pain, sleepiness, obesity and other cold diseases.

Seventeen effects
Seventeen effects describe the functions of medicine including soft, heavy, warm, greasy, solid, cool, dull, cold, mild, watery, dry, thin, hot, light, sharp, rough, and moving. For example, Heyi syndrome always shows symptoms of dizziness. In MM, light means your spirit is light instead of heavy and excessive light cannot stabilize your spirit inside your body, thus triggering dizziness. At the time, medicines with heavy effect need to play their role to balance the excessive light to treat dizziness. Most of them are produced from the six flavors and eight properties of medicine. These effects have a restraint or breeding relationship with the 20 features of Heyi, Xila, Badagan syndromes (six of Heyi, seven of Xila, seven of Badagan and the relationship between of Heyi, Xila, Badagan syndromes and the flavors, properties, effects of their symptomatic medicines can also be found in Table 4). The relationships are as follows: in the treatment of Heyi, the soft can restrain the coarse, the heavy can restrain the light, the warm can restrain the cool, the greasy can restrain the tiny and firm, and the solid can retrain the active, in treatment of Xila, the cool can restrain the greasy, the blunt can restrain the sharp, the cold can restrain the hot, the mild can restrain the light, the watery can restrain the smelly, and the dry can restrain the damp, in treatment of Badagan, the thin can restrain the greasy, the hot can restrain the cold, the light can restrain the heavy, the sharp can restrain the blunt, the coarse can restrain the soft and sticky, and the active can restrain the hard. According to different diseases, MM chooses the seventeeneffect drugs to treat diseases caused by the unbalance of the three elements and brings them on track, thus achieving the purpose of treating diseases.

Two powers
Two powers refer to the hot or cold power of medicines. In ancient times, Mongolian people believed that everything contained two opposite aspects and in terms of medicine, syndromes can be divided into hot and cold syndromes. Cold-power medicine is used to treat the hot syndromes and vice versa (Yixi, 2007). Medicines with hot power grow mostly in warm and hot areas or places with sufficient sunshine, thus they possess the hot power. Heyi and Badagan syndromes and dyspepsia can be treated with hot power medicines, but side effects such as dizziness, headache and fever can be triggered when using hot-power medicines. Medicines with cold power grow mostly in cold areas or shady places, so they possess the cold power. Xila syndromes can be treated with cold power medicines, but side effects such as dyspepsia and body rigidity.

Principles of Mongolian materia medica formula
The principles of Mongolian materia medica formula are mainly depended on the flavors, the flavors after digestion (they refer to three flavors which mean the salty flavor becomes the sweet flavor, the pungent and astringent flavors become bitter, the sweet, bitter and sour flavors are constant, so the final flavor is sweet, bitter and sour after the digestion of six flavors) and the effects of the medicines. Flavor formulas consider the original flavors of each medicine and are widely used in decoctions. For example, SanWei DangYao Decoction (it consists of Swertiae Herba, Gentianae Flos and Ophiopogonis Radix) can treat Heyi syndromes due to the bitter flavor of Swertiae Herba, Gentianae Flos and Ophiopogonis Radix in it. Flavor-after-digestion formulas consider the three flavors of medicines after digestion. After digestion, the sweet flavor can reduce Heyi and Xila, the sour flavor can reduce Badagan and Heyi and bitter flavor can reduce Xila. For example, after digestion BaWei ShiLiu Powder (it contains eight medicines including Punicae Granati Semen, Myristicae Semen, Cinnamomi Cortex, Piperis Longi Fructus, Zingiberis Rhizoma and so on) turns into sour flavor and reduces excessive Heyi and Badagan. Formulas prescribed with effects is the most widely used clinical method today. The seventeen effects and unique functions of medicines can be used as the basis for this formulation principle. When treating eye and ear diseases, Phellodendri Chinese Cortex is mostly recommended to be included in the formula for its beneficial effects to eyes and ears.
In clinical application, under the guidance of theories, several suitable drugs are chosen and combined in the right proportions and then made into certain dosages according to different syndromes and principles. When the drug's flavors and symptoms perfectly match, the medicine is the most effective for the disease. Mongolian materia medica formulas depend on flavors, properties, and effects. These methods are not a simple accumulation of flavors, properties or the effects of the medicine, but a combination of main medicines and adjuvant medicines (Bagana, 2007).
The main medicines play an important role in treating the disease, such as nutmeg for heart Heyi, Glehniae Radix for the lung heat, Bovis Calculus for the liver heat and the white cardamom for the kidney Heyi. Generally, there are only one or two kinds of main medicine in a prescription usually with a high dosage.
Adjuvant medicines play the role of strengthen the efficacy of main medicine, restrain the toxicity, treat the minor symptoms and so on, and the dosage is usually the same or slightly less. For example, Chebulae Fructus is used to reduce the toxicity of Aconitum Kusnezoffii Radix. Some classical formulas are listed in Table 5.
To summarize, the formulas of Mongolian materia medica must follow the basic principles above and the coordination of main and adjuvant medicines. After reasonable compatibility, the effect of one single medicine can be strengthened or changed, toxicity can be restrained and negative effects can be removed or alleviated making the complete use of the medicine to achieve optimum clinical effects.

Modern research on several classical Mongolian materia medica formulas
Much effort and progress have been made in research on Mongolian materia medica since 1950s especially over the past 40 decades. Some examples of the classical Mongolian materia medica formulas are summarized in the following sections.
Ancient books introduced Wenguanmu Siwei Decoction for the treatment of arthritis and edema (Jigemude, 2015). Current studies focus more on its therapeutic effect on rheumatoid arthritis and anti-inflammatory effects. Modern research showed that Wenguanmu Siwei Decoction was able to treat rheumatoid arthritis and exhibits a good curative effect by reducing uridine triphosphate, calcitroic acid, dynorphin B and docosahexaenoic acid to normal levels (Wang, Li, Jiang, Pei, & Xu, 2018). Research also showed that Wenguanmu Siwei Decoction played an antiinflammatory role by reducing anti-inflammatory factors such as IL-6 and CTLA-4 (Liu, Li, Hu, & Shen, 2021) and significantly inacti-vating PI3K-AKT pathway with Sendeng-4 (Du et al., 2021). Ethanol extract of X. sorbifolia effectively restrained various inflammatory factors of rheumatoid arthritis (Jia et al., 2021).
According to Drug Standards for Mongolian Medicines formulated by the Ministry of Health of the People's Republic of China, Wenguanmu Siwei Decoction is only specified in its dosage, with 500 g Xanthocerais Sorbifoliae Lignum, 300 g Toosendan Fructus, 100 g Gardeniae Fructus, 100 g Chebulae Fructus and is expected to have its modern quality control measures.
Jianghuang Siwei Decoction treatment significantly reduced the levels of blood glucose, serum creatinine, blood urea nitrogen, urine microalbumin, serum uric acid and reduced renal fibrosis. Jianghuang Siwei Decoction treatment further significantly reduced serum TGF-b1 levels and downregulated the expression of HIF-1a, VEGF and TGF-b1 at both mRNA and protein levels to significantly ameliorate renal damage in diabetic nephropathy mice. Another research showed that Jianghuang Siwei Decoction combined with another two Mongolian medicines, Sugmul-10 and Narenmandul-11, can protect renal through regulating MMP-2 and TGF-b1 (Wang, A, Liu, Wang, & Wei, 2015).
Jianghuang Siwei Decoction was also included in the Drug standards for Mongolian Medicines formulated by the Ministry of Health of the People's Republic of China. The prescription is 25 g Curcumae Rhizoma, 25 g Tribuli Fructus, 20 g Gardeniae Fructus, 15 g Phellodendri Cortex and lacks modern quality control measures.

Gurigumu-7
Gurigumu-7 is an important Mongolian materia medica formula frequently used for liver diseases. Gurigumu is the flower of Carthamus tinctorius L. (Carthami Flos) and plays the major role in Gurigumu-7. Together with Gurigumu, other six individual  (Wang, Tang, & Zhang, 2015), phenolic acids , triterpene compounds (Ji, Li, & Ma, 2014), alkaloids like ephedrine. The compounds with hepatoprotective activities were proved to be triterpene compounds, phenolic acids and flavonoids in the methanol eluted fraction of Gurigumu-7 (Xu et al., 2016). In Gurigumu-7, Chebulae Fructus is another important medicine. According to the existing data, Chebulae Fructus is present in nearly half of Mongolian medicine and is known as the ''king of Mongolian medicine". It is not only used within the Mongolian people, but also gradually applied throughout the world. It has the effects of dispelling wind, dehumidification, dispersing cold and relieving pain. Tannins are the main components of Chebulae Fructus such as chebulinic acid, chebulagic acid, terchebin and gallic acid (Fig. 7) (Gao et al., 2016).
Research reported that Chebulae Fructus in Gurigumu-7 had convincing protective effects on the CCl 4 -induced acute liver injury by enhancing the anti-oxidative defense system, ameliorating inflammatory responses and inhibiting hepatocyte apoptosis (Li et al., 2020). In addition, some non-traditional medicinal functions have been reported. In vitro pharmacodynamic experiment demonstrated that the effective components of Chebulae Fructus possessed significant antibacterial effects, and were nontoxic and safe (Li et al., 2016). In another study, the ethyl acetate fraction of Chebulae Fructus was proved to exhibit an anti-diarrhea effect (Sheng et al., 2016).
The quality standards of Gurigumu-7 are also formulated in Drug Standards for Mongolian Medicines formulated by the Ministry of Health of the People's Republic of China. However, some modern studies have been carried out to give specific recommendations on quality control of Chebulae Fructus. A study suggested chebulagic acid, chebulinic acid and 1,2,3,4,6-penta-O-galloyl-b-D-glucose to provide good references for the quality assessment of Chebulae Fructus. The total ratio of the three compounds above may offer a guideline for determining quality of the drug: lower-grade ratio (12.4 ± 6.0), medium-grade ratio (8.8 ± 7.9), higher-grade ratio (3.2 ± 0.8) (Juang & Sheu, 2005).

Quality control of Mongolian materia medica
During the past, traditional knowledge of medicines mainly relied on teaching by precept and example from elder pharmacist and now, the state has issued many quality control standards. At present, standards for Mongolian materia medica are set in 1980s. The Inner Mongolia Mongolian medicinal material standard was published in 1986. In 1998, the Mongolian medicine volume for Drug standards of the Ministry of Health of the People's Republic of China was published. However, limited to the scientific research conditions and level at the time, these standards are more descriptive, with few quantifiable indexes. The standards are lagging for a long time, which restricts the supervision and inspection of Mongolian materia medica and severely affects the use and development of new drugs. For example, in the Mongolian medicine volume for Drug standards of the Ministry of Health of the People's Republic of China, microscopic identification is the only quality control method for seeds of Cynanchum thesioides without  TLC identification, moisture, ash, extract and other quality control methods. Currently, more than 60 % of MM prescriptions follow the drug standards for Mongolian medicines formulated by the Ministry of Health of the People's Republic of China in 1998. MM prescriptions following the 1998 drug standard are difficult to meet the national regulations for drug use in medical institutions in terms of active compound detection, safety evaluation, clinical reevaluation and so on. After more than 30 years of scientific and technological development, the contents of active compounds need to be included in the standards. Therefore, new technologies and methods and formulate new standards for Mongolian materia medica are urgently needed. On the other hand, the functional and therapeutic part of the instructions which express the indication and curative effects of the drug are unclear about the quality standard of Mongolian materia medica. Many classic prescriptions of MM are prescribed with Mongolian medical terms and approved in the early stage. It shows that there is a deviation in the understanding of the functions and main indications of classic Mongolian materia medica formulas in the Chinese instructions and modern disease indications. These deviations affect the use of drugs by doctors and patients and then may affect the sales of drugs themselves.
Currently, the most critical work for the quality control of Mongolian medicines is to reformulate the standards. As mentioned above, techniques such as using HPLC for the determination of compounds have not been used, indicating that the use of new methods such as DNA barcoding is far. Thus, existing scientific achievements should be used of and transformed into local or national standards as soon as possible. Both Mongolian description and Chinese description should be considered for the description of functions and indications.

Discussion
With the continuous national support for MM and the gradual attention of mankind to prevention and healthcare, the demand for natural drugs and natural health products is increasing. It provides good opportunities for the development of MM, but it also faces great challenges.
To improve the overall core competitiveness of Mongolian materia medica, we must admit the deficiencies that the active compounds of Mongolian materia medica are unclear and the quality standards are not perfect. The modern research on the material basis of pharmacodynamics should be performed according to the characteristics of MM. Combined with the successful modernization model of TCM and other ethnomedicine, the exploration for Mongolian materia medica modernization is urgently required. It is the key to the modernization of MM to further screen pharmacodynamics components and establishment of whole process quality control system based on quality markers and development new drug dosage forms to complete the transformation of new dosage forms of MM.
Second, in order to promote the modernization, standardization and industrialization of MM, we need to strengthen the transformation of achievements. More efforts are required to gain government funds and policy support thus to further increase scientific research investment and strengthen the development of key MM products.
To summarize, Mongolian materia medica has a long history with exact efficacy, rich resources and wide applications. We must seize the opportunity and make complete use of the potential advantages of Mongolian materia medica to gradually improve the market competitiveness and promote Mongolian materia medica for its use in disease prevention, treatment and healthcare.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.