MAGNOLIA BARK

by Subhuti Dharmananda, Ph.D., Director, Institute for Traditional Medicine, Portland, Oregon

Magnolia bark is a highly aromatic herbal material obtained from Magnolia officinalis (see Figure 1) of the Family Magnoliaceae. The pharmacy item is obtained by stripping the bark from stems, branches, and roots. The Chinese name for the herb, houpu, refers to the thick (hou) bark that is the unadorned (pu) portion of the plant. In modern times, it is common for magnolia bark to be sold to pharmacies in bundles of relatively uniform strips about 4 inches long.

This herb was first described in the Shennong Bencao Jing (1) around 100 A.D., as follows:

houpu is bitter and warm, non-toxic, mainly treating wind-stroke, cold damage, headache, cold and heat, fright qi, blood impediment, and dead muscle. It removes the three kinds of worms. It grows in mountains and valleys.

This description differs markedly from that relied on in subsequent Chinese texts, in which the herb is mainly used for stagnation of qi and moisture circulation in the abdomen (associated with digestive disturbance) and tightness in the chest (associated with impaired breathing). However, the treatment of "fright qi" is one of the persisting indications for magnolia bark in the traditional prescriptions: it treats syndromes that are caused by emotional distress, such as plum pit qi, digestive disturbance associated with fear and anxiety, and shortness of breath due to emotional turmoil. Although magnolia bark is no longer used in the treatment of worms, its antibacterial properties are recognized and may be responsible for its ability to alleviate discomfort due to some intestinal bacterial infections. It may be prepared with ginger juice to enhance its digestive promoting effects.

MAGNOLIA BARK IN TRADITIONAL FORMULAS

Magnolia bark was a common ingredient in many formulas described in the Shanghan Lun and Jingui Yaolue (ca. 220 A.D.). Among the smaller formulas (7 or fewer ingredients) in which magnolia bark is a major component were the following 11 prescriptions (2), subdivided into three categories (see Tables 1,2, 3).

Table 1: Formulas for internal accumulation, made with rhubarb and chih-shih.

Table 2: Formulas for digestive system weakness, made with ginger and licorice.

Table 3: Formulas for stagnation of qi in the chest with difficult breathing made with either ma-huang or cinnamon twig.

Magnolia bark was frequently included as an ingredient in Chinese herb formulas mentioned in famous herb guides over the centuries, though some of the Shanghan Lun formulations, such as Minor Rhubarb Combination and Pinellia and Magnolia Combination, have remained the central formulas in which magnolia bark is a major component. More often, magnolia bark is included in larger traditional formulas and thus serves as a relatively minor contributor to the total therapeutic effect.

Magnolia bark is an ingredient in several patent remedies used for digestive system disorders and abdominal bloating and discomfort (4, 5), such as Mu Xiang Shun Qi Wan, Kang Ning Wan (Pill Curing), Bao Ji Wan (Po Chi Pill), Huoxiang Zhengqi Pian, and Shu Gan Wan.

FRAGRANCE COMPONENTS

The unmistakable pleasant fragrance of magnolia bark is primarily the due to the presence of two groups of compounds: biphenol compounds (magnolol and honokiol are dominant; see Figure 2) that have a mild fragrance, and an essential oil (eudesmol is the main component; see Figure 3) that has a stronger fragrance. In samples of magnolia bark from different areas of China, the content of magnolol and honokiol were in the range of 2-11% and 0.3-4.6% respectively (5, 6). Eudesmol usually comprises just under 1% of the bark; this oil is also a component of atractylodes, an herb which has related therapeutic effects and a somewhat similar strong fragrance (in the rhizome that is used medicinally).

Magnolia bark is classified in the modern Chinese Materia Medicas along with a relatively small group of herbs that are said to resolve dampness through aromatic penetration (7). The fragrance is said to awaken the spleen to distribute dampness, and the fragrance can also penetrate through damp accumulations to assist in breaking them up and allowing the fluids to flow freely. The main herbs in this category are various cardamons (e.g., caodoukou, baidoukou, sharen, caoguo), one of the atractylodes (cangzhu), eupatorium (peilan), and pogostemon (huoxiang). Of this group, magnolia bark, atractylodes, and pogostemon are the most extensively used today, often appearing together in formulas aimed at relieving digestive disturbances.

The biphenols and eudesmol (a triterpene) are the main active constituents that confer the desired pharmacological effects. These ingredients are reported to have anxiolytic effects (8), to enhance steroid production by the adrenal cortex (9), inhibit fungi (10) and bacteria (6), have antioxidant actions (11), reduce inflammation and pain (12); they may protect against seizures (13) and act as an antidote for intoxication by organophosphorus pesticides(14). Magnolia bark also contains a small amount of alkaloids, mainly magnoflorine, magnocurarine, and salicifoline, but these are not considered important to the clinical actions.

TOXICITY AND ADVERSE EFFECTS

No significant toxicity or adverse effects have been reported to date. In a 1993 article in Lancet (15), magnolia was mentioned along with stephania (Stephania tetrandra) as suspected ingredients in a complex weight loss regimen that resulted in several cases of renal failure. It was later reported that the herb stephania had come from the source Aristolochia fangchi (16) and suspicion about contribution to the incidence of renal failure was transferred to components of that herb, particularly aristolochic acid, which is not found in magnolia bark. There was no further investigation of magnolia in relation to the problems experienced at that clinic and there is no reason to suspect that it played a role. Laboratory studies of the toxicity of magnolia bark and its components failed to reveal any immediate reason for concern about its use in normal doses: the LD₅₀ of magnolia bark in decoction given by injection was 6 grams per kilogram in mice and the LD₅₀ of the alkaloid magnofluorine was 45 mg/kg by injection in mice. The mean lethal dose of magnolia bark decoction given to cats by intravenous administration was 4.25 g/kg.

DOSAGE

The usual dosage recommendation for magnolia bark in decoction is 3-9 grams (6, 17). It is also powdered in formulas made in pill form, in which case the daily dose ingested is typically less than 1 gram. Since prolonged boiling of the bark may reduce the content of essential oils and biphenols, the decoction requires a higher dose than the powder that is ingested in pills.

PRODUCTION

Virtually all of the magnolia bark collected for the herb market comes from cultivated supplies. Jingning County of Zhejiang Province is one of the largest production areas. Currently, China produces about 200 tons per year of magnolia bark, but there is a project underway in Jingning County to increase production to 1,500 tons per year if greater international distribution of magnolia bark and its products can be attained (18).

Most of the magnolia bark is used domestically (within China) both for making decoctions and patent medicine pills. Crude magnolia bark is exported to Chinese communities abroad that use it in making decoctions, and to Western companies that make Chinese herb products in capsule and tablet form (typically with powdered magnolia or dried extract of magnolia). Also, magnolia bark from China, Taiwan, and Japan is used in making Kampo remedies: traditional formulas prepared as dried decoctions (granules). These are used mainly in Taiwan and Japan where they are used domestically, and a portion is exported to Western countries. Both single herb granules and formulas are produced, and most of the formulas are the ones from the Shanghan Lun and Jingui Yaolue, as outlined above (there are also a few additional formulas that have a larger number of ingredients that were not listed in that section).

SUBSTITUTES AND RELATED HERBS

houpu is the official herb in the Pharmacopoeia of the People's Republic of China (17); the herb is sometimes called chuan houpu, because it originally came from the Sichuan area of China). Tuhoupu (tu = local; it is especially used in Guangxi Province) is sometimes used as a substitute (19). This herb is derived from species of Manglietia, which is in the same family as Magnolia. Studies show that houpu has higher levels of magnolol and honkiol, but lower levels of magnoflorine compared to tuhoupu. In Japan, Magnolia obovata is used as a source of houpu; it is called hehoupu (he = peaceful, harmonious).

REFERENCES

1. Yang Shou-zhong (translator), The Divine Farmer's Materia Medica, 1998 Blue Poppy Press, Boulder, CO.
2. Hong-Yen Hsu and Chau-Shin Hsu, Commonly Used Chinese Herb Formulas with Illustrations, 1980 rev. ed., Oriental Healing Arts Institute, Long Beach, CA.
3. Fratkin J, Chinese Herbal Patent Formulas: A Practical Guide, 1986 Shya Publications, Santa Fe, NM.
4. Chun-Han Zhu, Clinical Handbook of Chinese Prepared Medicines, 1989 Paradigm Publications, Brookline, MA.
5. Tang W and Eisenbrand G, Chinese Drugs of Plant Origin, 1992 Springer-Verlag, Berlin.
6. Zhu YP, Chinese Materia Medica: Chemistry, Pharmacology, and Applications, 1998 Harwood Academic Publishers, Amsterdam.
7. Hong-Yen Hsu, et al., Oriental Materia Medica: A Concise Guide, 1986 Oriental Healing Arts Institute, Long Beach, CA.
8. Kuribara H, et al., The anxiolytic effect of two oriental herbal drugs in Japan attributed to honokiol from magnolia bark, Journal of Pharmacy and Pharmacology 2000; 52(11): 1425-1429.
9. Wang SM, et al., Magnolol stimulates steroidogenesis in rat adrenal cells, British Journal of Pharmacology 2000; 131(6): 1172-1178.
10. Bang KH, et al., Antifungal activity of magnolol and honokiol, Archives Pharmaceutical Research 2000; 23(1): 46-49.
11. Kong CW, et al., Magnolol attenuates peroxidative damage and improves survival of rats with sepsis, Shock 2000; 13(1); 24-28.
12. Wang JP, et al., Antiinflammatory and analgesic effects of magnolol, Archives Pharmacology 1992; 346(6): 707-712.
13. Chiou LC, Ling JY, and Chang CC, Chinese herb constituent beta-eudesmol alleviated the electroshock seizures in mice and electrographic seizures in rat hippocampal slices, Neuroscience Letters 1997; 231(30; 171-174.
14. Chiou LC, Ling JY, and Chang CC, beta-Eudesmol as an antidote for intoxication from organophophorus anticholinesterase agents, European Journal of Pharmacology 1995; 292(2): 151-156.
15. Vanherweghem JL, et al., Rapidly progressive interstitial renal fibrosis in young women associated with slimming regimen including Chinese herbs, Lancet 1993; 34:387-391.
16. Vanhaelen M, et al., Identification of aristolochic acid in Chinese herbs, Lancet 1994; 343: 174.
17. Pharmacopoeia Commission of PRC, Pharmacopoeia of the PRC, (English edition) 1988 People's Medical Publishing House, Beijing.
18. Si Jinping, Jingning Magnolia officinalis Development Project, 2000 Jingning Science and Technology Development Department, Zhejiang, China
19. Song WZ, Cui JF, and Zhang GD, Studies on the medicinal plants of the Magnoliaceae tuhoupo of Manglietia, Journal of Chinese Herbs 1989; 24(4); 295-299.

Figure 1: Magnolia officinalis.

Figure 2: Magnolol and honokiol.

Figure 3: alpha-eudesmol and beta-eudesmol