Amur Cork Tree (Huang Bo)

Cortex PhellodendriIt is well known that Amur cork tree, or called phellodendron amurense in scientific name and Huang Bo in mandarin, is partly grown for the purpose as timber, which is the preferred type of wood for building houses and making high-end furniture because it comes with moderate hardness, graceful wood grain, and strong corrosion-resistance properties. Similarly, this plant, especially its bark, is also an equally remarkable Chinese herb thanks to its strong anti-inflammatory effect. As a matter of fact, it is a must-have ingredient in all kinds of traditional Chinese medicine pills. Unfortunately, in recent years the growing role of its medicinal value results in excessive illegal logging and the diminishing Amur corktree resources. So, in this case it needs to avoid abusing this herb. And as herbalists, what we can and should do is to better understand and make better use this herb medicinally.

What is Amur cork tree?

Medicinally Huang Bo refers to the dried bark of Phellodendron chinense Schneid. (Chuan Huang Bo) or Phellodendron amurense Rupr. (Guan Huang Bo), which are plants in the family of Rutaceae. Therefore, this herb is commonly known as Huang Bai, Amur cork tree bark, phellodendron amurense bark, phellodendron, cortex Phellodendri, phellodendron bark, nark of Chinese corktree, Amur corktree bark, cortex phellodendri Chinensis, Amur cork bark, and so on. The former is mainly produced in Sichuan, Guizhou, Hubei, Yunnan and other places and the latter is mainly produced in Liaoning, Jilin, Hebei and other places. It is usually peeled after the Qingming Festival in spring. After the peeling, remove the tertia, dry in the sun and flatten, moisturize thoroughly, slice or shred them, and use them raw, processed with salt water, or charred.

Amur cork tree plant is a deciduous tree, 10 to 25 meter. Outer bark is gray, with thick cork layer and longitudinal-fissure surface, and under bark is bright yellow. Branchlets are usually brown or light brown, but red-orange rarely. Odd pinnately compound leaf is opposite, with 5 to 13 leaflets, and a small short petiole. Inflorescence is paniculate. Rachis and flowers are pubescent when young. Flowers are unisexual, dioecious, and small. Berry-like drupe is spherical, about 8 to 10mm in diameter, dark purple when mature, and with five seeds inside. Its flowering period is from May to June and the fruiting period is from September to October.

It contains a variety of alkaloids, limonin (obaculactone), obacunone, obacunonic acid, 7-dehydrostigmasterol, β-sitosterol, campesterol, and so on. And alkaloids mainly include berberine, phellodendrine, magnoflorine, jatrorrhizine, palmatine, and more.

Chinese Amur cork tree bark benefits

This herb was first found in “Shen Nong’s Herbal Classic”, in which it was listed as the highest grade and classified into the group of heat-clearing and damp-drying drug. The best medicinal quality usually comes from those phellodendron that is about 10 year old. Unfortunately the tree will die soon after it is peeled. As a result, it is also one of rare and valuable Chinese herbs. Clinically it is usually used for the treatment of cerebrospinal meningitis, bacillary dysentery, pneumonia, tuberculosis, liver cirrhosis, chronic hepatitis, trichomoniasis vaginitis, acute conjunctivitis, chronic suppurative otitis media, cervical spondylosis, ear eczema, and more. And its pharmacology seems have more related information and evidence.

Modern pharmacological actions of Amur cork bark

1. It resembles Huang Lian (Coptis Rhizome) on fighting pathogenic microorganism and inhibits many pathogenic bacteria, such as dysentery bacillus, typhoid bacillus, Mycobacterium tuberculosis, Staphylococcus aureus, hemolytic streptococcus and others;
2. It inhibits certain skin fungi, leptospirosis, and hepatitis B virus surface antigen;
3. Its jatrorrhizine contained has similar positive inotropic action and antiarrhythmic effect with berberine;
4. Amur cork tree extract has a variety of health benefits, such as bringing high blood pressure down, healing ulcer, sedation, muscle relaxation, lowering blood sugar, and promoting the generation of the mouse antibody.

Popular Amur corktree herbal remedies

Based on Chinese Materia Medica, it is bitter in taste and cold in properties and covers two meridians of kidney and bladder. Chief functions are clearing away heat and drying dampness and purging fire for removing toxin. Basic Amur cork tree uses and indications are damp-heat dysentery, diarrhea, jaundice, nocturnal emissions, stranguria with turbid discharge, morbid leucorrhea, hectic fever due to yin deficiency and consumptive fever, mouth sores, swollen red eyes, ulcer sores, and skin eczema. Recommended dosage is from 3 to 9 grams in decoction, teapills, or powder.

1. Bi Xie Fen Qing Yin. From Yi Xue Xin Wu (Understanding of Medical Science), it is mainly formulated for damp-heat invasion of bladder, scanty dark urine, and hot painful urination. Other major herbal ingredients are Bei Xie (Dioscorea Root), Fu Ling (Poria), Che Qian Zi (Plantago Seed), etc.

2. Bai Tou Weng Tang. From Shang Han Lun (On Cold Damage), this formula is normally designed for dysentery due to the large intestine heat. Other prime herbs are Bai Tou Weng (Pulsatilla), Coptis Rhizome, Qin Pi (Cortex Fraxini), and so on.

3. Huang Lian Jie Du Tang. From Wai Tai Mi Yao (The Secret Medical Essentials of a Provincial Governor), this prescription is basically made to cure sores. Other herbs include Huang Qin (Scutellaria), Coptis Rhizome, Zhi Zi (Gardenia), and more.

4. Zhi Bai Di Huang Wan. From Yi Zong Jin Jian (Golden Mirror of Orthodox medicine), this recipe is primarily used for fire excess from yin deficiency, tidal fever and night sweating, lower back pain, and nocturnal emission. The rest important herbs are Zhi Mu (Anemarrhena Rhizome), Sheng Di Huang (Rehmannia), Shan Yao (Chinese Yam), etc.

5. Hu Qian Wan. From Dan Xi Xin Fa (Dan Xi’s Heart Methods of Treatment), it is commonly used for flaccidity syndrome caused by fire excess from yin deficiency. The rest essential herbs are Anemarrhena Rhizome, Shu Di Huang (Rehmannia), Gui Jia (tortoise shell), and more.

Amur corktree bark side effects and contraindications

The safety of Amur corktree bark is also a major concern. And it was rated with a class 2B by the AHPA. That’s to say, it should be avoided in pregnant women. And it is reported that overdose of this herb may lead to vomiting and nausea. According to Ben Cao Jing Ji Zhu (Explanation of Canon of Materia Medica), it contradicts Gan Qi (Resina Toxicodendri). Besides, it shouldn’t be used in the cases of diarrhea caused by spleen deficiency and deficiency-cold in spleen and stomach.

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