Licorice Extract for Parkinson’s Disease

Node Smith, ND

Liquiritigenin, an Extract of Licorice Root, may be used to Treat Parkinson’s Disease

A new study on the herbal extract, liquiritigenin, an extract of licorice root, has uncovered a mechanism by which the herb may be used to treat Parkinson’s disease by inhibiting neuronal cell death.1 Parkinson’s disease is a degenerative disease which progresses due to apoptosis of specific dopaminergic cells in the brain. As these cells die off, the symptoms of tremor, stiffness, slow motion and postural instability progress. The current route of Parkinson’s treatment has largely been to increased prevalence of available dopamine as well as stimulate an increase in endogenous production of the neurotransmitter, and then finally, exogenous administration of dopamine analogs. The search for a mechanism by which to stop the cellular death and halt or reverse disease progression has long been sought after.

Key Mechanisms of Dopaminergic Neuronal Apoptosis & Ways to Control

Dr. Yun-II Lee has led a team of researchers who have discovered some of these key mechanisms of dopaminergic neuronal apoptosis as well as a potential way to control them. According to the study, cellular stress activates Poly ADP-ribose polymerase-1 (PARP-1) which induces excessive accumulation of Poly ADP-ribose (PAR) which in turn activates Apoptosis-Inducing Factor (AIF). AIF ultimately results in the destruction of DNA and cellular death. This new mechanism of cellular demise is distinct from apoptosis (which is highly regulated and “planned” cellular death), and has been labeled Parthanatos, and is specific to this PAR-1 regulated cell death occurring from an over-accumulation of PAR. Parthanatos has been implicated in many degenerative diseases including diabetes and cardiac ischemic disease.

No Medications Exist that Inhibit this Type of Dopaminergic Neuronal Cell Death

Currently, there are no medications which are government sanctioned to inhibit this type of dopaminergic neuronal cell death. However, this Korean research team has shown promising results using a licorice extract. The idea to use licorice extract may have come about from its known ability to inhibit cortisol breakdown. This is relevant because researchers have found that cortisol promotes dopaminergic neural activity and inhibits the death of dopaminergic cells in the brain.

The current study found that liquiritigenin, a licorice extract, can induce RNF146 expression, a protein which removes excessively accumulated PAR and inhibiting dopamine neuronal cell death. It is thought that this occurs through estrogen receptor binding.

The study does conclude that liquiritigenin may be used as a treatment for degenerative Parkinson’s disease.


  1. Hyojung Kim, Sangwoo Ham, Joon Yeop Lee, et al., “Estrogen receptor activation contributes to RNF146 expression and neuroprotection in Parkinson’s disease models,” Oncotarget 2017
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Node Smith, ND, is a naturopathic physician in Portland, OR and associate editor for NDNR. He has been instrumental in maintaining a firm connection to the philosophy and heritage of naturopathic medicine among the next generation of docs. He helped found the first multi-generational experiential retreat, which brings elders, alumni, and students together for a weekend camp-out where naturopathic medicine and medical philosophy are experienced in nature. Four years ago he helped found the non-profit, Association for Naturopathic ReVitalization (ANR), for which he serves as the board chairman. ANR has a mission to inspire health practitioners to embody the naturopathic principles through experiential education. Node also has a firm belief that the next era of naturopathic medicine will see a resurgence of in-patient facilities which use fasting, earthing, hydrotherapy and homeopathy to bring people back from chronic diseases of modern living; he is involved in numerous conversations and projects to bring about this vision.

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