What is Magnolia Tree?
The magnolia tree (Magnolia officinalis), known as Houpu in Chinese medicine, is found in Southeast Asia. It was traditionally used to treat gastrointestinal (GI) disorders, anxiety, depression, nervous disorders, asthma, and allergic diseases.
The magnolia tree has a fragrant aroma and bright flowers. During the summer, the root and bark from the trees are harvested, dried, slightly boiled, and let to turn a purple-brown color. After being softened by steaming and rolling, this bitter and fragrant extract is used in medicine and dietary supplements for its various health benefits .
Components of Magnolia Bark
Magnolol and honokiol are lignans that are the major active components of magnolia bark extract. Various alkaloids (aporphine and benzylisoquinoline derivatives) and volatile oils (consisting of sesquiterpenoid alcohols, α-, β-, and γ-eudesmol) make up the rest of the extract .
Mechanism of Action
Honokiol prevents the formation of necrotic tissue in rat brains by stopping neutrophil (immune cells that kill damaged cells and harmful pathogens) activity and neutralizing reactive oxygen species such as hydrogen peroxide .
Honokiol prevents neurotoxicity by inhibiting the production of nitric oxide by an enzyme called nNOS. This enzyme depends on calcium, which is allowed into cells by a glutamate (a neurotransmitter) receptor called the NMDA receptor. However, if too much calcium is taken in by the cells, this leads to the production of pro-oxidants like superoxide and peroxynitrite and ends in cell death [5, 6, 7, 8, 4, 9].
Honokiol and magnolol block glutamate receptors in mice, preventing glutamate from binding to them. This prevents the glutamate-activated NMDA receptor from being activated too much, preventing seizures and premature cell death. Overstimulation of NMDA receptors is associated with many neurological disorders including epilepsy, stroke, mood disorders, and Alzheimer’s [10, 11, 4].
By stimulating the GABA-A receptor, honokiol produces a relaxing and calming effect. Honokiol also binds to the benzodiazepine site of the GABA-A receptor of neurons, impacting sleep cycles and helping with insomnia [12, 4, 13].
Health Benefits of Magnolia Bark
1) Magnolia Bark May Help with Depression
Serotonin is a neurotransmitter that allows for rapid signaling between neurons in the brain. Psychological disorders such as depression, mania, and anxiety are often linked to low levels of serotonin [16, 17]
Noradrenaline (norepinephrine) is a neurotransmitter that is heavily involved with the onset of depression. Low levels of noradrenaline can cause decreased energy, inability to concentrate, decreased alertness, and decreased cognitive abilities. Noradrenaline is also involved in regulating emotions .
2) Magnolia Bark May Help with Anxiety
Honokiol has been shown in animal studies to reduce anxiety with fewer side effects than diazepam, a drug commonly prescribed for anxiety disorders. Honokiol increases GABA levels, which helps decrease anxiety [4, 13].
3) Magnolia Bark May Help Prevent Cavities
A cell study showed that magnolol and honokiol, key components of magnolia bark, have significant antimicrobial activity against the bacteria Streptococcus mutans. S. mutans can be harmful to oral health, as it creates an acidic environment that makes plaque buildup possible, which destroys enamel and leads to the formation of cavities [19, 20].
4) Magnolia Bark May Reduce Inflammation
In a study involving magnolia bark extract administered to cells involved with the initial immune response (activated fibroblasts and monocytes), the extract effectively lowered the number of proinflammatory cytokines IL-6, IL-8, MMP-2, and MMP-9 .
5) Magnolia Bark May Protect Against Brain Damage from Seizures
Honokiol helped prevent and reduce the severity of seizures and reduced impairments in the movement of mice by blocking NMDA receptors .
6) Magnolia Bark May Prevent Memory Loss and Learning Impairments
Scopolamine is an anti-nausea drug that causes memory and learning impairments. Honokiol improved spatial learning and memory function in mice given scopolamine and reduced levels of the proinflammatory cytokines IL-1β while increasing levels of the anti-inflammatory cytokine IL-10 .
An alcohol extract of magnolia bark helped prevent memory loss caused by bacterial lipopolysaccharides in mice. Lipopolysaccharides are a toxin found in Gram-negative bacteria that activates the cells that protect the brain from attack from pathogens (microglia) by triggering the release of cytokines.
Chronically-activated microglia cause oxidative stress, leading to neuron damage and death. Eventually, these effects may contribute to the onset of neurodegenerative diseases like Alzheimer’s disease [24, 25].
7) Magnolia Bark May Help Reduce Pain Caused by Inflammation
Honokiol and magnolol reduced pain caused by drug-induced inflammation in mice but did not reduce pain caused by heat or force .
Glutamate and glutamate receptors, as well as the inflammatory molecules substance P and prostaglandin E2, are known to increase the sensitivity to pain. One study found that honokiol and magnolol prevented inflammatory pain in mice injected with glutamate .
8) Magnolia Bark May Help Prevent and Fight Cancer
Honokiol inhibits the activity of the proteins Nf-kB and STAT3 (transcription factors), which prevent cancer cell communication and tumor spread and growth. Also, by preventing the activation of STAT3, honokiol decreases the activation of the signaling molecules c-Src and EFGR, which are often abundant in cancer cells .
Honokiol applied to the skin of mice resulted in an 80% decrease in benign tumor size and a 62% decrease in the progression of benign tumors to malignant tumors .
Mice with lung cancer that were treated with honokiol and radiation saw a 78% reduction in tumor volume. This combination was more effective than either honokiol or radiation alone .
Honokiol prevented the growth of various types of breast cancer cells and also made drug treatment more effective by blocking the production of P-glycoprotein, a protein that pumps foreign substances out of cells, which reduces the effectiveness of chemotherapy .
Mice containing human ovarian cancer cells that were treated twice weekly with honokiol saw an 88% inhibition in tumor growth and an increased lifespan .
Honokiol containing human prostate cancer cells administered orally to mice increased the amount of cell death (apoptosis) at tumor sites and slowed the growth of cancer .
A cell study involving human colorectal cancer cells found that honokiol led to increased cell death at tumor sites and prevented tumor growth .
Honokiol caused cell death in human gastric cancer cells in a cell study and in mice with gastric cancer. It also decreased the production of key molecules involved in tumor growth (Peroxisome proliferator-activated receptor-gamma (PPAR-gamma), COX-2 and 15-lipoxygenase (LOX)-1) .
A cell study on human pancreatic cancer cells found that honokiol caused cancer cell death and increased the effectiveness of the chemotherapeutic drug gemcitabine .
9) Magnolia Bark Helps with Symptoms of Menopause
In a study (RCT) of 934 women experiencing menopause, tablets containing a combination of magnolia extract and a soy-based supplement were given once a night for 12 weeks. The women experienced improvements in insomnia, anxiety, depression, and libido .
10) Magnolia Bark May Help with Insomnia
Honokiol promoted NREM, or dreamless sleep, in mice. Magnolol increased both NREM and REM sleep episodes by increasing the amount of GABA released from neurons in the brain. Magnolia extract overall was found to exhibit a relaxing effect .
In a study (DB-RCT) of 89 menopausal women, magnolia extract combined with a magnesium supplement helped alleviate sleep disturbances .
11) Magnolia Bark May Help with Weight Loss
12) Magnolia Bark May Help Lower High Blood Pressure
Honokiol significantly relaxed aortas and reduced blood pressure in rats with high blood pressure .
13) Magnolia Bark May Help with Asthma
A cell study done on immune cell production showed that magnolia extract can block the type 4 allergic reaction (delayed response type caused by the overactivity of T lymphocytes, which are involved in the adaptive immune system). Magnolol and honokiol provide a relaxing effect that dilates bronchial vessels in the lungs, allowing for easier breathing, as seen in a study involving pig trachea contraction and relaxation .
In a study of 148 mild and moderate asthma patients taking corticosteroids for their condition, the magnolia extract was effective in improving asthma control and preventing extreme attacks .
14) Magnolia Bark May Help with Symptoms of Enlarged Prostate
In a cell study, prostate gland tissue treated with honokiol reduced smooth muscle contraction and prevented excessive cell growth, indicating magnolia extract may help with symptoms of enlarged prostate in men .
15) Magnolia Bark May Treat Diabetes
16) Magnolia Bark May Help Delay Progression of Alzheimer’s Disease
Magnolol and honokiol decreased neuron death by protecting them from high calcium levels and inhibiting caspase, an enzyme that breaks down muscle-specific proteins and causes cell death.
Side Effects and Contraindications
Those with a bleeding disorder or clotting disorder are not recommended to take magnolia supplements. This includes those who have hemorrhages or patients with disorders such as hemophilia or von Willebrand’s deficiency .
Multiple animal studies reported no change in diet, appetite, weight, or other body activities. No mutations were observed and toxicity tests done over 90 days reported no mortalities .
Limitations and Caveats
While the research strongly supports the use of magnolia bark in benefiting multiple conditions and diseases, most of it has been conducted in rodents. Therefore, caution is warranted when applying this information for use in humans.
Patients taking anticoagulants such as Coumadin or Lovenox should not take magnolia bark extract as it reduces blood clotting .
Dietary supplements often contain magnolia bark extract in doses between 200 mg to 800 mg taken daily .
One user noted that they fell asleep much quicker and had better sleep.
Another user experienced better sleep and lowered anxiety levels. However, they noted that the effect diminished after a couple of days.
Some users report headaches and drowsiness.