Honokiol: A Promising Compound for Supporting Mental Health, Reducing Inflammation and as an Antimicrobial
Honokiol is a constituent of magnolia tree bark, an herb with a long history of use in Chinese herbal medicine. Historically, the bark has been used for treating anxiety, depression, asthma, gastrointestinal concerns and other conditions (Poivre 2017). On its own, honokiol appears to hold promise for providing a number of different benefits similar to magnolia tree bark’s historical uses, including:
- Supporting mental health
- Reducing pain and inflammation
- Providing antimicrobial effects
However, like a lot of promising natural therapies, clinical trials with honokiol are limited. Current data is based mostly on animal studies. While the data is promising, human clinical trials can help to validate real-world treatment efficacy.
Honokiol and Mental Health
Numerous studies in animal models suggest benefits with honokiol for anxiety and depression. Standard medication-based treatments for anxiety often included benzodiazepine medications. These medications are known to be addictive among having other serious concerns with regular use. In a study on mice, honokiol was shown to have comparable anxiety reducing effects without the problems encountered with benzodiazepines (Kuribara 1999).
Other studies have found antidepressant-like effects. A study in mice that induced depression symptoms by increasing inflammation through the administration of bacterial toxins showed benefits with honokiol (Sulakhiya 2014). When mice were pretreated with honokiol before the inflammatory challenge, depression symptoms were significantly reduced. Honokiol worked through a number of mechanisms, decreasing inflammation, improving antioxidant defenses and increasing brain-derived neurotrophic factor, a cellular growth factor that supports brain cells. Other studies in mice confirm potential anti-inflammatory benefits that also reduce depressive symptoms (Jangra 2016, Zhang 2019).
A separate model of depression through the administration of excess stress hormone in rats found honokiol was effective at minimizing the pathological response (Zhang 2020). Excess stress hormones can induce a state similar to depression in animal models. When rats were administered honokiol at the same time, the stress response and subsequent depressive behaviors were prevented.
Honokiol and Inflammation
While some of the mental benefits of honokiol appear to be from its anti-inflammatory properties, these anti-inflammatory effects aren’t limited to the brain. Research also suggests the anti-inflammatory effects might be relevant for other health conditions.
In a study of an autoimmune model of arthritic joint pain, honokiol was able to stabilize the disease. Additionally, the anti-inflammatory effects increased with increasing doses of honokiol. The authors suggest that honokiol could be a valuable non-toxic approach to treat inflammatory autoimmune conditions (Munroe 2007).
Other animal models of pain also appear to show benefits with honokiol (Khalid 2018). In the research, honokiol had significant pain-reducing effects without any indications of toxicity. The effects appeared to be mediated through honokiol’s anti-inflammatory mechanisms.
The anti-inflammatory and antioxidant mechanisms of honokiol can also prevent organ damage. Animal studies have shown that honokiol can protect the kidneys from damage due to blood-borne infections (Xia 2019). Other research shows that honokiol can protect the heart from damage during a heart attack (Wang 2013).
Antimicrobial Effects of Honokiol
Beyond mental health support and anti-inflammatory effects, honokiol also appears to have significant antimicrobial properties. For bacteria, honokiol has been shown to kill the microbes that cause gum disease (Ho 2001, Chiu 2021), although effects against other pathogenic bacteria were more limited.
The antifungal effects of honokiol appear to be even more impressive than its effects on bacteria. Low concentrations of honokiol were able to inhibit numerous fungal pathogens, including species of trichophyton that cause ringworm and candida (Bang 2000). Other in-vitro (in a petri dish) research found that honokiol was comparable in strength to standard prescription antifungal medications for killing some specific fungal pathogens (Oufensou 2019).
Honokiol, a compound derived from the bark of magnolia trees, has preliminary evidence suggesting potential utility for treating mental health conditions, inflammation and as an antimicrobial for oral pathogens and fungi. Hopefully, future clinical trials can help to further clarify its effects as a potential treatment in humans.