Radix Rehmanniae
- Name
- Origin
- Where Does It Grow?
- Nature and Flavor
- Identified Active Components / Major Chemical Constituents
- Drug Actions in TCM
- Traditional Uses in TCM
- Pharmacological Actions
- Toxicology
- Administration and Dosage
- Adverse Effect, Side Effects and Cautions
- References
Name
Latin Name: Radix Rehmanniae
Common Name: Rehmannia root
Scientific Name: Rehmannia glutinosa Libosch.
Chinese Name: 乾地黃 / 生地
Pinyin Name: gan di huang / sheng di
Origin
The dried root tuber of Rehmannia glutinosa Libosch., of the Scrophulariaceae family.1
Where Does It Grow?
Rehmannia root is widely distributed throughout China. Nowadays, it is mainly cultivated in Henan and Zhejiang provinces, other districts such as Hebei, Shensi, Gansu, Hunan, Hubei, Sichuan, and Shanxi are also produced. The production of Henan is regarded as the genuine one.1,3,6
Nature and Flavor
Rehmannia root is cold in nature, sweet and bitter in flavor, and mainly manifests its therapeutic actions in the heart, liver and kidney meridians.2
Identified Active Components / Major Chemical Constituents
Rehmannia root contains sterol, glycosides and polysaccharides, its active components are mainly iridoid glycosides, such as catalpol, rehmanniosides A-D, leonuride, aucubin, melittoside, jioglutoside A-B, 6-O-E-feruloyl ajugol, rehmaglutins A-D, glutinoside, purpureaside C, echinacoside, jionosides A1 & B1, cistanosides A & F, and acteoside. Its polysaccharides include stachyose, raffinose, glucose, sucrose, fructose, manninotriose, galactose and rehmannia glutinosa polysaccharides (RPS-b). Rehmannia root also contains over 20 kinds of amino acids, as well as alkaloids, phosphoric acid, organic acids, adenosine, trace elements, lecithin and vitamin A. Because of the drying and baking processes, part of the polysaccharides were decomposed in the dried herb, and the levels of catalpol, leonuride and aucubin might only be remained about 66%, in comparing with the fresh herb.3,5,6
In the Pharmacopoeia of People's Republic of China (2010 Edition) - Part I, the level of catalpol should not less than 0.20%, and the acteoside should not less than 0.020%, which are the standard qualities of rehmannia root.
Drug Actions in TCM
Rehmannia root clears heat, cools blood, nourishes yin and promotes body fluids production.2Traditional Uses in TCM
Rehmannia root is often used in conditions like fever, fluid exhaustion, consumptive diseases, bleedings, anemia, dizziness, palpitations, and menstrual disorders.2,4,5
Rehmannia root is an important ingredient for clearing heat, cooling blood and stop bleeding.
According to TCM theory, infectious diseases are associated with external pathogens attacking the inner body (entering the nutrient and blood stages), individuals may have high fever, a red tongue, bleeding under the skin, or vomiting blood or nose bleeding. Rehmannia root can be used along with figwort root, peony root bark, red peony root and gardenia fruit in the remedies. An overheated digestive track may lead to pass bloody stool, which can be treated with rehmannia root along with golden thread rhizome, garden burnet root, and pagoda tree flower. Bloody urine may be due to damp-heat in the lower burner, which can be treated with rehmannia root combining with couch grass rhizome and field thistle herb. Uterine bleeding can also be a heat sign, in which rehmannia root can be used with baical skullcap root and cattail pollen. In addition, modern TCM often uses rehmannia root in the treatment of low blood platelet count.
Rehmannia root is an important ingredient for clearing heat, nourishing yin and promoting body fluid production.
After feverish conditions, some individuals may remain a persistent low fever that typically experienced in the evening, a disharmony named as yin deficiency in TCM. Physicians like to prescribe rehmannia root along with sweet wormwood herb, soft-shelled turtle carapace and anemarrhena rhizome for relief. When the individual has constipation or hard stools, then the herb can be used with dwarf lily-turf tuber and figwort root to smooth and lubricate the bowel movements; when there are poor appetite and mouth dryness, the herb can be used with coastal glehnia root, fragrant Solomonseal rhizome and germinated barley to promote the digestive secretions and functions.
Rehmannia root is a common ingredient for chronic and consumptive diseases.
Yin deficiency is a common presentation in immune disorders, such as SLE, Sjogren’s syndrome, rheumatoid arthritis, rheumatic fever, erythema nodosum, myocarditis, anaphylactod purpura, IgA nephropathy, urticarial, allergic dermatitis, psoriasis and eczema, which are categorized as consumptive conditions. Other chronic diseases such as hypertension, diabetes, diabetes insipidus, nephritis, hepatitis and asthma are also put in this category. Since individuals usually develop a depleted state, rehmannia root is often prescribed with cornus fruit, Chinese yam, poria, peony root bark, oriental water-plantain rhizome, snakegourd root, Chinese wolfberry, and astragalus root to supplement the body, relieve symptoms, enhance overall functioning and assist the routine treatments.
Fresh rehmannia root is colder in nature that has similar actions as the dried rehmannia root, its yin nourishing actions are weaker, but it has stronger abilities in clearing heat, cooling blood, stop bleeding and promoting body fluid production.
Pharmacological Actions
The actions of rehmannia root include regulating blood sugar, blood pressure and immune functions. It can also affect the pituitary-adrenal and thyroid secretions, as well as anti-inflammation, cooling body, diuresis, anti-tumor, anti-aging, liver protection, promoting blood clotting, stimulating blood cells growth and gland secretions.5
Toxicology
When rats were administered by gavage with rehmannia root water extract and ethanol extract 60g/kg for three days, 18g/kg for 15 consecutive days, no toxic reactions had seen.7
Administration and Dosage
Orally, the usual dose is 10～15g, it can be up to 30g if necessary. Fresh herb should be double the dose. Beside decoction, it can be prepared as syrup, pills, powder, juiced or ground for external applications. When taking as supplement, the daily suggestion is about 10g.2,5
Adverse Effect, Side Effects and Cautions
Individuals with poor appetite, loose bowels, gastric or abdominal discomforts, excessive secretion in the throat or airway problem should use with caution. Some individuals may have enhanced bowel movements.5
References
- Li Jiashi (editor-in-chief), Chinese Medicine Identification, Shanghai Scientific and Technical Publishers, 2000-2.
- Lui Daiquan (editor-in-chief), Chinese Herbal Medicine, Shanghai Scientific and Technical Publishers, 2000-6.
- Zhao Zhongzhen & Xiao Peigen (editor-in-chief), Contemporary Medicinal Herbal Glossary, Hong Kong Jockey Club Institute of Chinese Medicine, 2006-8.
- Tao Yufeng, Clinical Herbal Medicine, People’s Medical Publishing House, 2005-5.
- Chen Pian, Clinical Application of Tonifying Herbs, Second Military Medical University Press, 2008.
- http://www.zysj.com.cn/zhongyaocai/yaocai_g/gandihuang.html
- Cai Yongmin et al (editor-in-chief), Newly Chinese Herbal Pharmacology and Clinical Applications, Hua Xia Publishing House, 1999-1.
