- Magnolia bark extract
- Houpu magnolia
For Patients & Caregivers
How It Works
Magnolia bark extract has shown anti-inflammatory and anticancer effects in laboratory and animal studies, but clinical trials are needed to test its effects in humans.
Magnolia officinalis is an herb commonly used in traditional medicine. The bark contains active compounds, honokiol and magnolol that may reduce inflammation, anxiety, or depression. A number of laboratory studies also suggest that bioactive compounds from magnolia bark extract may have anticancer properties, but no studies have been conducted in humans. In addition, this botanical has been shown to inhibit several enzymes or pathways by which many drugs are metabolized. Therefore, clinical trials are needed to determine safety and effectiveness.
To prevent cancer
Laboratory studies suggest magnolia bark extract has anticancer properties, but clinical trials are needed to confirm these effects as well as safety.
To treat diabetes
Magnolia bark extract and its active compounds lowered blood sugar in the lab, but human studies are needed.
To prevent inflammation
Animal studies have shown that magnolia bark extract reduces pain and inflammation.
As an antibacterial agent
Lab studies suggest magnolia bark extract may reduce the bacterium that causes acne and some types of infections, but no studies have been done in humans.
Do Not Take If
- You are taking diabetes medications: Magnolia bark extract may enhance their effects.
- You are taking sleep or anxiety medications: Magnolia bark extract may increase their effects.
- You are taking blood thinners: Magnolia bark extract may increase the risk of bleeding.
- You are taking cytochrome P450 substrate drugs: Magnolia bark extract may alter the effects of these drugs.
- You are taking P-glycoprotein substrate drugs: Magnolia bark extract may alter the effects of these drugs.
- You are taking UDP-glucuronosyltransferase (UGT) substrate drugs: Magnolia bark extract may alter the effects of these drugs.
- Skin rash has been reported with the use of cosmetics containing magnolia bark extract.
Because so few studies have been conducted in humans, other side effects are currently not known. However, lab studies suggest that this botanical may interact with a number of drugs. Therefore, clinical trials are needed to determine safety and side effects.
For Healthcare Professionals
Magnolia officinalis is an oriental flowering herb that has been used in traditional Chinese medicine to treat anxiety, depression, stress, nervousness, and sleep-related problems. The tree bark contains the active constituents magnolol and honokiol.
In vitro and in vivo studies suggest these compounds have antimicrobial (1) (2), anti-inflammatory (3) (4) , antidiabetic (5) (6), antidepressant (7), anxiolytic (8), and neuroprotective (9) effects. Preclinical studies have evaluated their anticancer potential. Magnolol demonstrated activity against a variety of cancers, including bladder (10) (11) (12), prostate (13) (14) (15) (16), colorectal (17) (18), breast (19) (20), and lung (21) (22) cancers . Honokiol also showed antitumor and antiangiogenic effects (23) (24) (25) in leukemia (26), lung (27) (28), bladder (29), prostate (30), melanoma (31) (32), breast (33), glioblastoma (34), neuroblastoma (35), and oral cancer (36) cells lines. Other animal studies suggest honokiol may enhance low-dose docetaxel treatment against prostate cancer growth and bone metastasis (37).
A few preliminary studies have been conducted in humans, and showed benefits for vasomotor symptoms (38), weight management (39), and oral health (40), but these studies were performed in combination with other compounds. There are no clinical trials conducted in humans to evaluate magnolia bark extract for its cancer preventive properties.
Magnolia bark extract and its constituents may inhibit several enzymes or pathways by which many drugs are metabolized, including cytochrome P450 (CYP450), UDP- glucuronosyltransferase (UGT), and P-glycoprotein (P-gp) expression (41) (42). Therefore, there is the potential for interactions with many medications.
Mechanism of Action
In THP-1 cells, magnolol and honokiol reduced inflammatory TNF-α and interleukin-8 (IL-8) production induced by Propionibacterium acnes (3). Other anti-inflammatory markers reduced by magnolia bark extract include IL-6 as well as matrix metalloproteinase 2 (MMP2) and MMP9 (4) . Antihyperglycemic effects with magnolia bark extract are attributed to the inhibition of protein tyrosine phosphatase enzyme 1B, a negative regulator of the insulin signaling pathway, which increases ERK phosphorylation and GLUt4 translocation (5). Magnolol increased both insulin-stimulated glucose transport and production of GLUT1 and GLUT4 mRNA, and GLUT4 protein (6).
A combination of honokiol and magnolol normalized biochemical abnormalities in brain 5-HT and 5-HIAA, serum corticosterone levels, and platelet adenylyl cyclase activity, a biomarker for depression in chronically stressed rodents (7). Anxiolytic effects of honokiol are attributed to its selective stimulation of GABA-A receptors or its binding to anxiety-related sites (8).
A number of anticancer mechanisms have been identified with magnolol. In human bladder cancer cells, it induced p27KIP1-mediated G2/M-phase cell cycle arrest to activate the extracellular signal-regulated kinase pathway (11), and decreased the binding of transcription factor NF-kappaB to DNA to inhibit MMP9 expression (12). In prostate cancer cells, magnolol affected the expression of insulin-like growth factor-1 (IGF-1) and associated binding proteins (13), inhibited the EGFR/PI3K/Akt signaling pathway (16), and downregulated MMP2 and MMP9 protein and mRNA levels (15). Antitumor activity also occurred via MMP9 inhibition through the NF-kappaB pathway in breast cancer cells (19) and through AMPK activation in colorectal cancer cells (18).
Antitumor and antiangiogenic properties of honokiol are attributed to nuclear factor kappa beta (NF-kB) inhibition and the consequent scavenging of reactive oxygen species (24). In human endothelial cells, honokiol inhibited vascular endothelial growth factor receptor 2 (VEGFR2) phosphorylation (25). It also blocked VEGF-induced Rac to prevent migration of malignant endothelial cells (25), blocked signaling pathways in tumor cells with defective p53 (23), and suppressed NF-kB overactivity (24). In acute myeloid leukemia cells, honokiol inhibited STAT3 signaling via increased protein tyrosine phosphatase SHP1 expression (26). In glioma cells, it induced autophagy and activated a p53/cyclin D1/CDK6/CDK4/E2F1-dependent pathway to induce apoptosis and cell cycle arrest (34) and in prostate cancer cells, honokiol suppressed c-Myc protein expression (30).
In animal models of prostate cancer with bone metastasis, honokiol induced apoptosis via caspase-3,-8, and -9 activation and poly (ADP-ribose) polymerase (PARP) cleavage (37). As a potential P-glycoprotein (P-gp) inhibitor, constituents of magnolia bark extract may reduce multi-drug resistance in cancer cells via P-gp downregulation (42) (43).
Herb Lab Interactions
- Cytochrome (CYP) P450 substrates: In vitro, honokiol inhibited CYP1A2, CYP2C8, CYP2C9, CYP2C19, and may alter activities of the drugs metabolized by these enzymes (41).
- UDP-glucuronosyltransferase (UGT): Honokiol inhibited UGT1A9 in vitro, suggesting it may interfere with activities of drugs metabolized by this enzyme (41).
- P-Glycoprotein (P-gp) substrates: Honokiol downregulates P-gp expression (42) and may interfere with the metabolism of certain drugs.
- Antiplatelet agents: In animal studies, magnolol also demonstrated antiplatelet activities (46) and may therefore increase the risk of bleeding when used with these drugs.
- Antidiabetic agents: Laboratory studies suggest that Magnolia bark extract and magnolol have hypoglycemic effects (5) (6) and may increase the effects of these medications.
- Benzodiazepines: Magnolia bark extract and honokiol may increase the effects of these medications (47).