Yuan Zhi is a staple of Traditional Chinese Medicine (TCM), and though we aren't sure exactly how long it has been in use, it is one of the oldest continuously used treatments that is still prescribed today by TCM practitioners. Recent scientific analysis and research have proven the mechanisms behind Yuan Zhi's many benefits. As one of the most important plants used in TCM to treat memory loss, it has also shown promise in treating cognitive and neurodegenerative diseases and has emerged as a potent ally in fighting cancers.
What is Polygala tenuifolia (Yuan Zhi)?
Polygala tenuifolia is a Traditional Chinese Medicine herb that is also known as Yuan Zhi, Senega, Chinese Senega, Mountain Polygala, Seneca/Senega Snakeroot, Snakeroot, Milkwort, Polygala, Polygala Root, Rattlesnake Root, Senega Snakeroot, and Seneka. Many people call Polygala tenuifolia “Senega Root” and “Chinese Senega.” However, there is a separate species called Polygala senega that is also called Yuan Zhi, so there is confusion between the distinction of the two species. Our discussion today focuses specifically on Polygala tenuifolia (Yuan Zhi). [1, 2]
Polygala tenuifolia belongs to the genus Polygala in the family Polygalaceae. Polygala is known as “milkworts” and “snakeroots.” They are annual or perennial small trees and shrubs which have purple flowers. The name Polygala is derived from an ancient Greek word which translates into “much milk” due to the belief that the plant can increase milk production in dairy cattle. [2, 3, 4]
“Yuan Zhi” is a specific species of Polygala tenuifolia called Polygala tenuifolia Willdenow or one of its varieties, P. sibrica Linnaeus. It grows in the mountain slopes, grasslands, prairies, and shrub forests of China, Mongolia, Korea, and Russia. [4, 5]
Yuan Zhi means “Profound Will” in Chinese. The Chinese use the roots of the Polygala tenufolia plant, and therefore, it is also called Radix Polygalae. “Radix” is a term that refers to the root of a plant in botany. [6, 7]
What is the history of Polygala tenuifolia (Yuan Zhi)?
- China: Polygala tenufolia (Yuan Zhi) was used in ancient China in their Traditional Chinese Medicine (TCM) therapy. It is still a popular treatment in the present-day. Yuan Zhi was first mentioned in a book, Jingyue Quanshu, in 1624 as a treatment for dementia and memory loss; but the Chinese have been using Yuan Zhi for an indefinite amount of time. [8]
TCM defines Yuan Zhi as a neuroprotective agent. It is one of the three most common plants used for memory enhancement in TCM. TCM physicians believe that it balances the qi of the kidneys and heart and can stabilize the emotions and fortitude (will). It is listed as a mucolytic (expectorant) to treat cough in the Chinese Pharmacopoeia. As one of the 50 fundamental herbs that are used in TCM, Yuan Zhi has a history of being used by Buddhist monks for enhanced cognition and focus during meditation. Yuan Zhi was also used traditionally to relax the body for sleep, and it is a nootropic herb. [2, 5, 9]
- Japan: Kampo, the traditional Japanese medicine philosophy, uses Yuan Zhi in some of their herbal formulations for Yuan Zhi's cognitive benefits. The formulations used in Kampo are Kami-kihi-to, Kami-untan-to, Ninjin-yoei-to, and Kai Xin San. It is called “onji” in Japanese. [2, 10]
- Korea: Polygala tenuifolia is known as “wonji” in Korean. [11]
What is Polygala tenuifolia (Yuan Zhi) made of?
Yuan Zhi's active constituents include sucrose esters, saponins, acetylated sucrose molecules, xanthones, triterpenoid glycosides, phenyl propanoids, sterols, flavonoids, and polysaccharides.
- Tenuifolisides A, B, C
- Tenuifoliose A-X
- 3,6′-disaponylsucrose (DISS)
- Tenuifolin: 0.006% of dried root
- Saponins: tenuigenin, senegenin, senegenin III, tenuifoside A, polygalasaponin F, polygalasaponin XXXII
- Onjisaponins
- Sibiricose A1, A5, A6
- Yuanzhi-1: pentacyclic triterpenoid
- Tetrahydrocolumbamine
- 7-O-methylmangiferin, lancerin, shibiricaxanthone A
- Assorted triterpenoid glycosides
- Chondrillasterol
- 3β-O-β-Pyranoglucosyl Chondrillasterol
- Clionasterol and its derivatives
- Poligapolide
- Phenyl propanoids: 3,4,5-trimethoxy methyl cinnamate; 3,4,5-trimethoxycinnamic acid
- Xanthones
- Flavonoid: 3'4,'-Dimethoxy-7-diglucosyl-O-methylenoxy-5-hydroxyl-flavol
- Sterols
- Polysaccharides: 5.27% of weight from dried root [2]
How is Polygala Tenuifolia (Yuan Zhi) prepared?
Yuan Zhi is harvested in the fall and then dried in the sunlight. The dried root bark is split open and the xylem (the tissue in the plant that transports water from the roots) is extracted through vigorous rubbing. The xylem is then dried again and can be used directly or in a liquid medium. [12, 13]
What are the benefits of Polygala tenuifolia (Yuan Zhi)?
Polygala tenufolia (Yuan Zhi) enhances memory
This study concluded that an extract of Yuan Zhi roots, BT-11, enhanced memory in healthy adults.
This study focused on the extract BT-11 and concluded that it enhanced memory and cognitive functions in elderly adults.
Polygala tenufolia (Yuan Zhi) may treat Alzheimer's Disease
One of the mechanisms behind Alzheimer's Disease is the formation of toxic plaques formed by amyloid beta peptides (also known as amyloid beta plaques). Animal studies have demonstrated that Tenuigenin, a constituent of Yuan Zhi, inhibited the secretion and formation of amyloid beta plaques. [2]
Polygala tenufolia (Yuan Zhi) may protect against Parkinson's Disease
In animal studies, low doses of Yuan Zhi are protective against the oxidative stress of a Parkinson's disease model. The triterpenoids in Yuan Zhi, specifically polygalaspaonin F and tenuigenin, are believed to be responsible for this mechanism.
Polygala tenufolia (Yuan Zhi) relieves depression
In this study, Yuan Zhi's isolated constituents demonstrated that they exert antidepressant activity in rodents. This study focused on the triterpenoid saponins, Yuanzhi-1 to Yuanzhi-6.
This study focused on DISS (3,6′-disinapoyl sucrose), a constituent of Yuan Zhi, and found that it also had antidepressant effects.
Polygala tenufolia (Yuan Zhi) reduces anxiety
This study focused on the polygalasaponins extracted from Yuan Zhi and confirmed that it has anxiety-reducing (or anxiolytic) effects, as well as sedative effects in mice.
Polygala tenufolia (Yuan Zhi) reduces drug hyperactivity
In a study involving the polygalasaponins extracted from Yuan Zhi, it was concluded that it is an antipsychotic agent (or major tranquillizer) and reduced cocaine-induced hyperactivity via dopamine and serotonin antagonist properties.
Polygala tenufolia (Yuan Zhi) is anti-inflammatory
This study concluded that Yuan Zhi is anti-inflammatory and can be useful in reducing inflammation in neurodegenerative diseases.
A study focusing on a constituent of Yuan Zhi, phenyl propanoid tenuifoliside A, demonstrated that tenuifoliside A is also anti-inflammatory.
Human clinical studies have led to a patent in France that is effective for eczema, multiple sclerosis, and psoriasis based on the anti-inflammatory activity of a triterpenic acid extract of Yuan Zhi. [1]
Polygala tenufolia (Yuan Zhi) improves sleep
In a study focusing on tenuifolin (a polygalasponin extracted from Yuan Zhi), researchers concluded that it significantly enhanced sleep in mice. This mechanism is due to its effects of activation of the GABAergic system and its involvement with the noradrenergic system.
Polygala tenufolia (Yuan Zhi) is an expectorant
The triterpenoid saponins found in Yuan Zhi are the active constituents with expectorant properties. The saponins cause a secretion of mucous in the bronchioles. [1]
Polygala tenufolia (Yuan Zhi) treats atopic dermatitis
This study demonstrated that Yuan Zhi extract reduced skin inflammation and scratching behavior in mice with atopic dermatitis.
Human clinical studies have led to a patent in France that is effective for eczema, multiple sclerosis, and psoriasis based on the anti-inflammatory activity of a triterpenic acid extract of Yuan Zhi. [1]
Polygala tenufolia (Yuan Zhi) fights cancer cells
In a study involving a polysaccharide protein tyrosine phosphatase of Yuan Zhi extract, the active constituent caused cell death of ovarian cancer cells.
In this study involving the same polysaccharide protein tyrosine phosphatase, it exhibited anti-tumor effects on tumor growth in ovarian cancer.
In another study involving ovarian cancer tumors in 2018, scientists demonstrated that the polysaccharide protein tyrosine phosphatase was a powerful chemopreventive agent even at an advanced stage.
In this study focusing on polysaccharide fractions, researchers also found that it has anti-tumor effects in lung cancer tumors.
How to Use Polygala tenuifolia (Yuan Zhi)
Yuan Zhi can be purchased as a dried roots, dried root powder, and tinctures. Use of Yuan Zhi is
best supervised by a Traditional Chinese Medicine practitioner.
Safety and Side Effects of Polygala tenuifolia (Yuan Zhi)
Long-term use of Yuan Zhi can cause gastrointestinal irritation, and large quantities may cause dizziness, diarrhea, nausea, and vomiting. [1]
Due to its gastrointestinal effects, it is not advisable to use Yuan Zhi if you have a gastrointestinal condition or disease, such as gastric ulcers or gastritis. It is believed that the saponins cause irritation of the mucosa of the GI tract. [1]
In toxicity studies, the no-observed-adverse-effect-level (NOAEL) in animals is 1,000 mg/kg daily, but it was concluded that Polygala tenuifolia was not toxic in dogs or rats. [14]
- References
- “Senega.” Foods, Herbs & Supplements. https://naturalmedicines.therapeuticresearch.com/databases/food,-herbs-supplements/professional.aspx?productid=679
- “Polygala tenuifolia.” Examine.com, last updated Jun 14, 2018. https://examine.com/supplements/polygala-tenuifolia/.
- “Polygala.” Wikipedia, en.wikipedia.org/wiki/Polygala.
- “Polygala Linn.” www.efloras.org/florataxon.aspx?flora_id=3&taxon_id=126390.
- Tang, Weici, and Gerhard Eisenbrand. “Polygala Tenuifolia Willd.” Chinese Drugs of Plant Origin, pp. 781–786., link.springer.com/chapter/10.1007/978-3-642-73739-8_99.
- P, Liu, et al. “Potential Antidepressant Properties of Radix Polygalae (Yuan Zhi).” Phytomedicine, vol. 17, no. 10, Aug. 2010, pp. 794–9., www.ncbi.nlm.nih.gov/pubmed/20541923.
- Xie, Huisheng, and Vanessa Preast. ” Xie's Chinese Veterinary Herbology.” ISBN 978-0-8138-0369-2.
- Liu, Ping, et al. “History and Experience: A Survey of Traditional Chinese Medicine Treatment for Alzheimer's Disease.” Evid Based Compelement Alternat Med, vol. 2014, doi: http://dx.doi.org/10.1155/2014/642128.
- Van der Linden, Michael. “Yuan Zhi Therapeutic Uses – Polygala Tenuifolia, Seneca.” 21 Jan. 2018, www.lindenbotanicals.com/2018/01/21/yuan-zhi-therapeutic-uses/.
- “Yuan Zhi.” www.rootdown.us/Herbs/Yuan Zhi?
- HK, Park, et al. “Occupational Asthma and Rhinitis Induced by a Herbal Medicine, Wonji (Polygala Tenuifolia).” J Korean Med Sci., vol. 20, no. 1, Feb. 2005, pp. 46–9., www.ncbi.nlm.nih.gov/pubmed/15716601.
- “Yuan Zhi.” tcmwiki.com/wiki/yuan-zhi.
- “Polygala Tenuifolia – Willd.” pfaf.org/user/Plant.aspx?LatinName=Polygala tenuifolia.
- Shin, Ki Young et al. “Preclinical Safety of the Root Extract of Polygala tenuifolia Willdenow in Sprague-Dawley Rats and Beagle Dogs.” Evidence-based complementary and alternative medicine : eCAM vol. 2014 (2014): 570134. doi:10.1155/2014/570134
