1 Botanical Identity

Bajitian, the root of How in the family of Rubiaceae, is one of the most popular Chinese herbal medicine native to the Lingnan range in southern China. It is cultivated in Guangdong and Fujian provinces, and is used as a health food. The medicinal root of M. officinalis is cylinder-shaped (with round circumference of the section) and slightly curved. The surface is yellowish-gray or dark gray. The bark of the root is thick, violet or light violet in colour, and easy to separate from the xylem. It is used for medicinal purposes. There are 20–25 species of genus Morinda in the world. But some related species, such as M. shuanghuaensis C.Y. Chen et M.S. Huang, M. parvifolia Bartl. et DC. are often adulterants. Only M. officinalis How is the legal source recorded in the Pharmacoepia of People’s Republic of China [1] and all historical records of Chinese herbal works. Typically, M. officinalis grows to the height of between 40 and 60 cm. Leaves are opposite, oblong, 5–12 cm long, and 2–5 cm wide. Flowers are white and sessile with 2–10 jointed together to form a subglobose head that is 5–9 mm across. Fruits are syncarpous, yellow-red in color, 6–11 cm across, fleshy, and contain many pyrenes. Seeds are oblong and wingless [2].

Bajitian mainly comes from artificial cultivation. The root is harvested in late-fall, between November to December of the fourth or fifth years plant. Then washing, drying in the sun, individually beating with a wooden club when the root is 70–80 % dry, and returning them to the sun until completely dried. The final product often appears as broken 1–2 cm sections after removing the xylem as raw material, they have the appearance of a chicken’s intestine, hence called “Ji-chang-feng” (Chicken Intestine Feng). For different medicinal purposes, the raw materials are prepared as steamed Bajitian, salted Bajitian and liquoriced Bajitian, etc. [3] (Fig. 16.1).

Fig. 16.1
figure 1

The plant (a) and crude drug (b) of Bajitian

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2 Chemical Constituents

Anthraquinones, iridoids and oligosaccharides are the main bioactive compounds in the root of M. officinalis How. Other constituents, such as steroid, amino acid, volatile components and microelements can also be found [4, 5].

2.1 Anthraquinones

As the main effective component in the root of Bajitian, anthraquinones were first studied in 1986 [6]. They have extensive pharmacological effects as antibacterial, antivirus, antihypertensive lipid et al. So far, more than 20 anthraquinones have been isolated from Bajitian, which all share the same basic skeleton structure of anthraquinone with different other substituting groups like-methyl, -methoxyl, -hydroxy, and -hydroxymethyl. Rubiadin (1), Rubiadin 1-methylether (2) and Physcion (3) (shown in Fig. 16.2) are representative components and used as standard compounds for evaluation of the quality of crude drug Bajitian and related pharmaceutical or natural health product preparations containing Bajitian [4].

Fig. 16.2
figure 2

Representative anthraquinones, iridoids, and oligosaccharides isolated from Bajitian

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2.2 Iridoids

Iridoids, as one of the major classes of bioactive compounds in Bajitian, were found in 1987, right after anthraquinones. Monotropein (4) possesses a strong anti-inflammatory and analgesic effect, which is consistent with the effect of removing wind-dampness of Bajitian. Monotropein (4) and asperulosidic acid (5) are representative iridoids isolated from Bajitian [7] (shown in Fig. 16.2).

2.3 Oligosaccharides

Oligosaccharides, the significant compounds in the root cortex of Bajitian, are account for as much as 18.9 % of dry weight. Because of their high water solubility, significant activity in anti-depression and certain effect on improving reproductive capacity of Kidney-yang deficiency rats, oligosaccharides have been studied widely and deeply. Four inulin-type oligosaccharides were obtained for the first time in 1995 [8] in the study of anti-stress effect. Nystose (6, shown in Fig. 16.2) was used as the standard compound for evaluation of the quality of Bajitian in Chinese Pharmacopoeia (2010). More oligosaccharides, such as inulotriose, inulotetraose, and inulopentaose were isolated from Bajitian later [9].

3 Pharmacological Studies

As previously mentioned, Bajitian is one of the most popular and commonly used herbal medicines in TCM, especially for almost all the diseases related to the Kidney-yang deficiency. It has been extensively used as a Yang-tonifying drug for a long time in China. Warming and tonifying the kidney-yang and replenishing vital essence can be good for preventing or treating a wide range of symptoms, including depression, poor digestion, high blood pressure, respiratory problems, immune deficiencies, inflammation and osteoporosis. Modern pharmacological studies have indicated Bajitian to have the following multifarious biological activities: protective effect on bone loss and age-induced bone degeneration, anti-fatigue, antioxidant, hypoglycemic and immunomodulation agents [10]. The principal bioactive constituents of Bajitian are anthraquinones, which were reported to exhibit anti-inflammatory, antinociceptive, antioxidant, antihepatotoxic and antimutagenic, antiosteoporotic [11]. Oligosaccharides, another important constituents, have been shown to possess antidepressant, antistress and angiogenesis promoting effects [12].

4 TCM Applications and Dietary Usage

4.1 TCM Applications

Bajitian is one of the most commonly used herbal medicines and health-maintaining products. As the best known herb for kidney and related diseases, it shows the treatment and health-care function in the following five aspects: reinforcing kidney to strengthen yang, warming and tonifying the kidney-yang, storing the essence and dominating reproduction, strengthening the tendons and bones, and dispelling wind-dampness. Bajitian could be used on its own or in combination with other herbs based on TCM theory.

Common clinically use of Bajitian preparations including the following forms: (1) Bajitian Oligose Capsule [13]. It is composed of M. officinalis oligosaccharide. The capsule is the first anti-depression patented drug in China, selective serotonin reuptake inhibitor, which is developed by Beijing Tongrentang Co., Ltd. Bajitian Oligose Capsule is effective, similar to fluoxetine hydrochloride tablets and safe in the treatment of mild and moderate depressive episode, superior to the latter treatment of traditional Chinese medical symptoms. It is mainly used for the treatment of depressive disorders caused by deficiency of the kidney, such as depressed mood, panic, insomnia and dreaminess, anxiety and oversensitive, weary and feebleness, sexual hypoactivity, tinnitus and amnesia through tonifying the kidney-yang. (2) Compound Baji Capsule [14]. It composed of sixteen herbal components: M. officinalis, , , , Epimedium brevicornum and so on. It is mainly used for the treatment of waist and knee weakness and irregular menstruation. Besides, it is also helpful for osteoporosis. (3) Chuankezhi Injection [15]. Two herbs, and M. officinalis, have been used to prepare Chuankezhi Injection. The products was used as a kind of immunomodulator for the treatment of bronchial asthma in clinical. (4) Baji Zhenyang Tablets. It is composed of six herbal components: Epimedium brevicornum, Panax ginseng, , and M. officinalis. The product is one of the proprietary Chinese medicines for the treatment of male diseases like impotence. (5) Bajitian extract is a very convenient form of administration, which can be made from single Bajitian or mixed with other herbs. The significant advantage of this form is ease of use and readily available for absorption; (6) Preparations made from active components including polysaccharides, oligosaccharides, monotropein, anthraquinones are also in the market as chemical drugs.

4.2 Dietary Usages

As one of the most famous herbs and valuable dietary botanical materials, Bajitian has been used in many ways historically due to the effectiveness and sweet taste, such as Bajitian tea, Bajitian wine, Bajitian soup, Bajitian oral liquid, and Bajitian extract. The following dietary forms can be easily made at home.

4.2.1 Bajitian Teas [16]

Herbal tea made of Bajitian alone or mixed with other herbs is the most common way. For instance: Bajitian Tea composed of Bajitian (5 g) and black tea (3 g); The tea composed of Bajitian (12 g), Yizhiren (, 10 g) and Fupenzi (, 12 g) could be helpful for kidney deficiency; BajiShanzhuyu Tea composed of Bajitian (30 g) and Shanzhuyu (, 30 g), is useful for Nephrotic Syndrome in children with Cushing Syndrome; BajiGouqi Drink composed of Bajitian (15 g), Gouqizi (Lycium barbarum, 15 g). To make the herbal tea, softened water or natural water with less mineral and alkaline is recommended in order to reduce the decomposition of active ingredients.

4.2.2 Bajitian Wine [17]

Bajitian itself or combined with other herbs can be used to prepare herbal wine for Kidney-yang deficiency and related diseases. There are several typical examples: soaking Bajitian without xylem (60 g), Shudihuang (, 45 g), Gouqizi (Lycium barbarum, 30 g), Zhifuzi (processed , 20 g), Ganjuhua (, 60 g) and chuanjiao (Zanthoxylum, 30 g) in 1.5 L of Chinese spirit or vodka for 5 days or more. Drinking 25–50 mL daily is recommended; soaking Bajitian (1800 g) and Niuxi (Achyranthes bidentata, 1800 g) in 30 L of Chinese spirit or vodka for one week or more. Drinking 10–20 mL daily is recommended. In addition, Bajitian can also be used to make herbal wines in combination with many other herbs depending on the specific function need. Daily intake amount will be based on the content of herb and alcohol.

4.2.3 Bajitian Used in Medicated Foods

Bajitian can be used to make soups with rice or meat. A conventional and typical way is to boil Bajitian or combined with other herbs, such as Tusizi (), Rougui ( with rice or meat, such as chicken, pork, mutton and dog meat together. This nutritious rice porridge or soup can be used for endogenous cold syndrome marked by pallor, cold limbs, lassitude, weakness and soreness in the waist and knees, impotence, and sterility caused by Kidney-yang deficiency.

Red dates, black soya bean, peanuts, and most corns or vegetables can also be cooked with Bajitian to take advantage of the health-maintaining effect of Bajitian. The taste of Bajitian-containing foods can be adjusted based on personal preferences.

5 Clinical Evidences

Bajitian is mostly used in combination with Epimedium davidii Franch as tonic (i.e. Chuankezhi Injection and Yikang Medicinal Liquor). Clinical and observational studies reported the effect of Bajitian and its related preparations on diseases caused by depressed, immunodeficiency, and impotence. Bajitian may have effect on the function of hypothalamus-hypophysis-gonadal axis, and less reaction of the parasympathetic nerve-M receptor to cure impotence as well as depression. Its water extract showed anti-depression pharmacological activity on 18 patients [18]. For the Chuankezhi Injection, clinical reports showed that the preparation could cure mild and moderate asthma [15]. For Er-xian Decoction [19], clinical observation indicated that the prescription respond to Partial Androgen Deficiency in Aging Male (PADAM), especially for prostatitis patients.

6 Safety Evaluation and Toxicity Data

Few clinical reports on the toxicity or side effects are available which is directly related to the use of Bajitain. Animal studies also have shown no noticeable toxicity for various organs through oral administration. Dosage of 250 g/kg QID of Bajitian decoction was given to mice via oral administration; there was no death within 72 h. Its water extract showed no effect on the SOS response (DNA damage response) system of E. coli PQ37 in vitro, which indicated Bajitian water extract have no mutagenic or induced mutagenesis effect [20].

Though Bajitian is definitely a relatively safe herbal medicine often used in health-maintaining products and for the treatment of impotence, attention must also be paid when you decide to use this herb personally without doctor’s advice, as it is obvious that Bajitian has strong biological activity and cannot be used as a regular food. It’s strongly suggested to ask your doctor if it is right for you.