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EUCOMMIA BARK [杜仲, DU ZHONG]

Name : Eucommia barkDu-Zhong-3_opt

Chinese Name : 杜仲

Latin Name : Cortex eucommiae

Overview

This herb is the dried trunk bark of Eucommia ulmoides Oliv, of the family eucommiaceae. It is mainly grown in the Guizhou, Hubei, Sichuan, and Yunnan provinces of China. The bark is stripped of the tree beetween April and June, then dried in the sun after the cork has been removed, and cut into pieces. It is used unprocessed or stir baked with saltwater and dried. Eucommia bark is also known as mu mian (cotton tree), which refers to the fact that if the bark is broken and the fractured edges drawn asunder, a delicate, silvery, silky fiber may be pulled out for several inches without breaking.

Traditionally, unprocessed eucommia bark is good for arthralgia and the processed species is good for lumbago, impotence, hypertension, and stabilizing a fetus to prevent miscarriage.

Eucommia bark is used as a tonic to replenish the kidneys and the liver, tranquilize the mind, and strengthen the bones and muscles. It is used today for treating threatened abortion and to prevent miscarriage. Eucommia bark is a powerful antiaging medicinal herb.

Use of Eucommia Bark in TCM

Sweet in taste and warm, it acts on the liver and kidney meridians.

Effects, Medicinal Uses, and Combinations

  1. Invigorates the kidney yang and liver yang, and strengthens the bones and muscles: for ailment due to yang deficiency manifested as aches and pain in the loins and knees, lassitude of muscles, impotence, and frequent urination, eucommia bark is mixed with morinda, psoralea, cornus, dodder seed, and prepared rehmannia root.
  2. Prevents uterine and vaginal bleeding, soothes the fetus, and prevents habitual miscarriage:
  • For profuse uterine bleeding and unstable fetus, eucommia is combined with dipsacus root (xu duan) and Chinese dates, as in Du Zhong Wan, to stop bleeding, stabilize the fetus, and prevent habitual miscarriage.
  • Eucommia is also blended with ginseng root, white atractylodes, prepared rehmannia, white peony, loranthus, and donkey-hide gelatin to treat uterine bleeding due to both Qi and blood deficiency, and to prevent habitual miscarriage.
  1. Nourishes the kidney yin and liver yin, and lowers blood pressure: for hypertension, dizziness, and light-headedness due to kidney-yin and liver-yin deficiency or an excess of liver yang, eucommia bark is mixed with lycium fruit, loranthus (sang ji sheng), achyranthes root, prunella spike, scute root, and chrysanthemum in a decoction.

Dosage

In a decoction of 5 to 15 g.

Precautions

To lower blood pressure, eucommia alone is less effective for liver yang hyperactivity than in a compound prescription with other herbs.

Side Effects and Toxicity

No side effects were noted  at the recommended therapeutic dose. Oral administration of 15 g/kg of the herbal decoction in mice caused no mortality.

Chemical Contituents

Eucommia bark and leaves contain mainly lignans and iridoids. Twenty six lignan compounds have been isolated from the bark of the plant. The lignans are: pinoresinol, ulmoprenol, dulcitol, epipinoresinol, medioresinol, syringaresinol, hedroxy pinoresinol, cycloolivil kaempferol, ulmoprenol, ducitol, and other lignan compounds. Other ingredients and the iridoids compounds include aucubin, ajugoside, harpagile acatate, alkaloids, glycosides, vitamin C, caffeic acid, and potassium. Pinoresinol diglucoside is believed to be the major antihypertensive component and is mainly found in the phloem part of the bark.

Pharmacological findings:

  1. Lowers blood pressure. An aqueous extract of eucommia bark lowered blood pressure in pigs, rabbits, and dogs.
  2. Reduces blood cholesterol levels in rabbits and reduces the absorption of cholesterol
  3. Acts as a tranquilizer and diuretic in animal experiments
  4. Enhances immune activity and increases resistance againts diseases
  5. Inhibits the contraction of uterine muscles in rats and rabbits
  6. Other effects include sedative, analgesic, anti-inflammatory, diuretic, and antimicrobial.