Hou Po (Cortex Magnoliae Officinalis or Magnolia Bark)

What Is Hou Po

Hou Po commonly known as Cortex Magnoliae Officinalis or Magnolia Bark is the bark of the trunk, root, or branch of Magnolia officinalis Rehd.et Wils. or Magnolia officinalis Rehd.et Wils.var.biloba Rehd.et Wils., which is a deciduous tree belonging to the family Magnoliaceae. It is a relatively practical and common Chinese herbal medicine, which first appeared in <Shennong Ben Cao Jing> in the late Western Han Dynasty (around 100 BCE).

There are about 340 species of Magnolia, which are mainly distributed in East Asia, Southeast Asia, Eastern North America, Central America, and the West Indies. Only a few species are distributed in South America.
They have high economic value and are widely used in many fields such as gardens, architecture, and food. Among them, some plants are used medicinally, such as Magnolia biondii, M. denudata, and M. officinalis.

Magnolia officinalis Rehd.et Wils. like cool and moist environments. They often grow in mountain forests at an altitude of 300-1,500 meters. They are distributed in Shaanxi, Gansu, Henan, Hubei, Hunan, Sichuan, Guizhou, Guangxi, Jiangxi, and Zhejiang in China.

Magnolia officinalis

Magnolia officinalis Rehd.et Wils.var.biloba Rehd.et Wils is a subspecies of Magnolia officinalis Rehd.et Wils. They often grow in mountain forests at an altitude of 300-1,400 meters. They are distributed in Anhui, Zhejiang, Jiangxi, Fujian, Hunan, Guangdong, Guangxi, and Northeast China.

From April to June of each year, people peel the barks of the trunk, root, or branch of Magnolia officinalis Rehd.et Wils. or Magnolia officinalis Rehd.et Wils.var.biloba Rehd.et Wils., gather them separately, dry their root bark and branch bark, boil trunk bark slightly in boiling water, stack them in damp places, until their inner surface turns purple-brown or brownish, steam them into softness, roll them into tubes, dry them, use them directly, or stir-fry them with ginger juice, and make them into Chinese herbal medicines.

Hou Po contains magnolol, honokiol, 6′-O-methylhonokiol, 4-methoxyhonokiol, magnolignans A-D, honokitriol, magnaldehyde C, randainal, magnaldehyde B, eudesobovatol A-B, clovanemagnolol, eudesmagnolol, eudeshonokiol A, eudeshonokiol B, caryolanemagnolol, piperitylmagnolol, piperitylhonokiol, dipiperitylmagnolol, bornylmagnolol, houpulin F-J, obovatol, magnolignan G, syringaldehyde, coniferaldehyde, caffeic acid, vanilic acid, syringic acid, methyl caffeate, magnolianone, magnoloside A-E, magnoloside F-P, acteoside, magnoflorine, magnocurarine, asimilobine, oblongine, betaine, anaxagoreine, reticuline, liriodenine, roemerine, lirinidine, lysicamine, isosalsoline, quercitrin, afzelin, choerospondin, rutin, β-eudesmol, blumenol A-B, crytomeridiol, stigmasterol, daucosterol, uridine, and some trace elements.

Generally, solid and friable root bark and branch bark with a fibrous cross-section is preferred. The solid and oily trunk bark with small bright spots on the cross-section is preferred.

According to <Compendium of Materia Medica>, the medicinal nature of Hou Po is relatively warm, with a pungent and bitter taste. It has a therapeutic effect on pathological changes in the spleen, stomach, lung, and large intestine meridians.

In traditional Chinese medicine, it is often used to dry dampness, promote the circulation of qi, remove food retention, eliminate phlegm and relieve asthma, and treat abdominal distension, abdominal pain, nausea, vomiting, diarrhea, functional dyspepsia, constipation, anorexia, asthma, chest tightness, anxiety neurosis, depression, ileus, acute gastritis, chronic gastritis, gastroparesis, gastroduodenal ulcer, irritable bowel syndrome, myotonia, globus hystericus, early enteroparalysis, Heroin withdrawal symptoms, and Alzheimer’s disease.

There are about 300 kinds of traditional Chinese medicine prescriptions containing it, such as Ban Xia Hou Po Tang, Hou Po Ma Huang Tang, and Xiang Sha Yang Wei Wan.


  • Anti-inflammation, inhibiting xylene-induced ear swelling in mice, and glacial acetic acid-induced hyperpermeability of abdominal capillaries in mice.
  • Anti-oxidation, scavenging superoxide anion free radicals, hydrogen peroxide free radicals, hydroxyl free radicals.
  • Reducing CCL4-induced acute liver injury in mice and protecting the liver.
  • Reducing LPS-induced acute lung injury in mice and protecting the lung.
  • Inhibiting diarrhea induced by castor oil or senna leaf in mice.
  • Inhibiting platelet aggregation induced by arachidonic acid, collagen, and thrombin.
  • Increasing insulin levels and reducing blood glucose levels in type 2 diabetes model mice (modeled with a high-sugar and high-fat diet and streptozotocin).
  • Regulating the transcriptional activity of liver X receptor α (LXRα), increasing the expression of ABCA1 and ABCG1 downstream of LXRα in human monocyte cell line THP1 macrophages, and reducing blood lipids.
  • Reducing spontaneous hypertension in experimental animals and relieving hypertensive renal damage.
  • Prolonging the latency of epileptic seizures and reducing the level of epileptic seizures in pentylenetetrazol-induced epilepsy rats.
  • Drying dampness, and treating abdominal distention and pain, nausea, vomiting, and diarrhea caused by damp retention in middle-jiao.
  • Promoting the circulation of qi and removing food retention, treating abdominal distension and constipation caused by retention of food leading to stagnation of qi.
  • Eliminating phlegm and treating asthma, chest tightness, sputum-rales, and dysphoria.
  • Treating globus hystericus caused by depression due to seven emotions or mutual obstruction of phlegm and qi.
  • Its extract can improve the ability of learning, memory, and behavior of vascular dementia model rats, and prevent and treat Alzheimer’s disease.
  • Honokiol can stimulate sleep-promoting neurons in the ventrolateral preoptic area and has the effect of promoting sleep and anxiety [1].
  • Honokiol can ameliorate depressive behavior in forced swimming in depressed mice. This shows that it has a certain antidepressant effect.
  • Inhibiting the proliferation of colon cancer HCT116 cells, liver cancer HepG2 cells, cervical cancer HeLa cells, breast cancer MCF-7 cells, ovarian cancer OVCAR-3 cells, and gastric cancer MKN45 cells [2].
  • Its decoction has a certain inhibitory effect on Escherichia coli, Staphylococcus aureus, pneumococcus, diphtheria bacillus, hemolytic streptococcus, dysentery bacillus, bacillus subtilis, bacillus anthracis, salmonella, candida albicans, helicobacter pylori, and streptococcus mutans.
  • Studies have found that its ethyl acetate extract can enhance the gastrointestinal motility function of mice induced by hydrochloric acid, promote propulsion, reduce the area of ulcers, and increase the content of serum gastrin.


Side Effects

At present, no data has been found to show that adverse reactions will occur when Hou Po is taken at prescribed doses.

Animal experiments have shown that long-term use of Hou Po has accumulated toxic effects on the kidneys, which can lead to abnormal renal function, glomerular swelling, or renal tubule dilatation.

Precautions and Warnings

  • The dosage of Hou Po should be controlled at 3-10g.
  • It can be made into decoctions, pills, powders, or medicinal liquors.
  • People who are allergic to Hou Po should not take it.
  • It should not be taken at the same time as medicines containing Ze Xie (Rhizoma Alismatis), saltpeter, or aminoglycoside antibiotics such as streptomycin, gentamicin, kanamycin, and neomycin.
  • Patients with body fluid deficiency due to qi deficiency should not take it.
  • Pregnant women should not take it.
  • Breastfeeding women should consult a medical professional before taking it.
  • The unprocessed Hou Po is recommended for drying dampness and eliminating abdominal distention, and the ginger juice-fried Hou Po is recommended for relieving stagnant qi in the chest, regulating the stomach, and arresting vomiting.