Description
Magnolia bark (Magnolia officinalis) is a traditional Chinese medicine (where it is known in TCM as houpu or hou po) used since 100 A.D. for treating "stagnation of qi" (low energy) as well as a variety of syndromes, such as digestive disturbances caused by emotional distress and emotional turmoil.
Claims
Magnolia bark is used as a general anti-stress and anti-anxiety agent - so its claims typically center on general benefits in controlling stress and anxiety. Newer claims are emerging, however, to link magnolia's anti-stress benefits with control of the body's primary stress hormone, cortisol, and the myriad health benefits associated with normal cortisol levels (versus elevated cortisol, which has been associated with obesity, diabetes, osteoporosis, memory problems and suppressed immune function).
Theory
Magnolia bark is rich in two biphenol compounds, (magnolol and honokiol), which are thought to contribute to the primary anti-stress and cortisol-lowering effects of the plant. The magnolol content of magnolia bark is generally in the range of 2-10 percent, while honokiol tends to occur naturally at 1-5 percent in dried magnolia bark. Magnolia bark also contains a bit less than 1 percent of an essential oil known as eudesmol, which is classified as a triterpene compound, and may provide some additional benefits as an antioxidant.
Scientific Support
Two of the most popular herbal medicines used in Japan, one called saiboku-to and another called hange-kobuku-to, contain magnolia bark and have been used for treating ailments from bronchial asthma to depression to anxiety. Japanese researchers have determined that the magnolol and honokiol components of Magnolia officinalis are one thousand times more potent than alpha-tocopherol (vitamin E) in their antioxidant activity, thereby offering a potential heart-health benefit. Other research groups have shown both magnolol and honokiol to possess powerful "brain-health" benefits via their actions in modulating the activity of various neurotransmitters and related enzymes in the brain (increased choline acetyltransferase activity, inhibition of acetylcholinesterase, and increased acetylcholine release). Numerous animal studies have demonstrated honokiol to act as a central-nervous-system depressant at high doses, but as a non-sedating anxiolytic (anti-anxiety and anti-stress) agent at lower doses. This means that a small dose of honokiol, or a magnolia bark extract standardized for honokiol content, can help to "de-stress" you without making you sleepy, while a larger dose might have the effect of knocking you out. When compared to pharmaceutical agents such as Valium (diazepam), honokiol appears to be as effective in its anti-anxiety activity, yet not nearly as powerful in its sedative ability. These results have been demonstrated in at least half a dozen animal studies and suggest that magnolia-bark extracts standardized for honokiol content would be an appropriate approach for controlling the detrimental effects of everyday stressors without the tranquilizing side effects of pharmaceutical agents.
References
1. Hou YC, Chao PD, Chen SY. Honokiol and magnolol increased hippocampal acetylcholine release in freely moving rats. Am J Chin Med. 2000;28(3-4):379-84.
2. Kuribara H, Kishi E, Hattori N, Okada M, Maruyama Y. The anxiolytic effect of two oriental herbal drugs in Japan attributed to honokiol from magnolia bark. J Pharm Pharmacol. 2000 Nov;52(11):1425-9.
3. Kuribara H, Stavinoha WB, Maruyama Y. Behavioural pharmacological characteristics of honokiol, an anxiolytic agent present in extracts of Magnolia bark, evaluated by an elevated plus-maze test in mice. J Pharm Pharmacol. 1998 Jul;50(7):819-26.
4. Kuribara H, Stavinoha WB, Maruyama Y. Honokiol, a putative anxiolytic agent extracted from magnolia bark, has no diazepam-like side effects in mice. J Pharm Pharmacol. 1999 Jan;51(1):97-103.
5. Liu PS, Chen CC, Kao LS. Multiple effects of honokiol on catecholamine secretion from adrenal chromaffin cells. Proc Natl Sci Counc Repub China B. 1989 Oct;13(4):307-13.
6. Tachikawa E, Takahashi M, Kashimoto T. Effects of extract and ingredients isolated from Magnolia obovata thunberg on catecholamine secretion from bovine adrenal chromaffin cells. Biochem Pharmacol. 2000 Aug 1;60(3):433-40.
7. Tsai TH, Lee TF, Chen CF, Wang LC. Modulatory effects of magnolol on potassium-stimulated 5-hydroxytryptamine release from rat cortical and hippocampal slices. Neurosci Lett. 1995 Feb 15;186(1):49-52.
8. Watanabe, K., Goto, Y., Yoshitomi, K. "Central Depressant Effects of the Extracts of Magnolia Cortex." Chemical and Pharmcological Bulletin (Tokyo), 1973, 21: 1700-8.
9. Watanabe, K., Watanabe, H. Y., Goto, Y., Yamamoto, N., Yoshizaki, M. "Studies on the Active Principles of Magnolia Bark: Centrally Acting Muscle Relaxant Activity of Magnolol and Honokiol." Japanese Journal of Pharmacology, 1975, 25: 605-7. 10. Watanabe, K., Watanabe, H., Goto, Y., Yamaguchi, M., Yamamoto, N., Hagino, K. "Pharmacological Properties of Magnolol and Honokiol Extracted from Magnolia Officinalis: Central Depressant Effects." Planta Med, 1983, 49: 103-8.
