Polygala: A Comprehensive Encyclopedic Reference
1. Identity and Botanical Classification
1.1 The Genus Polygala
Polygala is a large genus of flowering plants belonging to the family Polygalaceae (the milkwort family). The genus includes several hundred species distributed across temperate and subtropical regions of the globe. In the context of dietary supplements and medicinal use, two species dominate the scientific and historical literature: Polygala tenuifolia Willd. (Chinese/Asian milkwort) and Polygala senega L. (Senega snakeroot, North American milkwort). A third species, Polygala sibirica L., is also listed as an official source plant in certain pharmacopeias and is used interchangeably with P. tenuifolia in some regional traditions. These species share chemical and pharmacological similarities — particularly a rich saponin content — yet have distinct geographical origins, traditional uses, and clinical research profiles.
1.2 Polygala tenuifolia Willd.
Polygala tenuifolia (yuǎn zhì; Chinese: 远志) is an herb in the family Polygalaceae. Common names include Senega, Chinese senega root, Chinese milkwort, Yuan Zhi (Chinese), and Onji (East Asia). It is a small perennial herb with thin wiry stems and little blue-purple flowers. This plant can be found growing wild throughout Asia, including China, Korea, and Siberia.
The plant's name in Chinese, Yuan Zhi, translates to "high aspirations." Its root — known as Polygalae Radix — has been used for over 2,000 years in Traditional Chinese Medicine. Polygala tenuifolia is officially listed in the Chinese Pharmacopoeia Commission, 2015.
1.3 Polygala senega L.
Polygala senega L. (Polygalaceae) is a perennial plant that grows in North America and reaches a height of about 30 cm; dried parts of the roots are used as drugs (Polygalae radix). Other common names include Seneca snakeroot, seneka snakeroot, rattlesnake root, mountain flax, milkwort, northern senega, and polygala root. Senega root is native to North America and can be found from Newfoundland to Alberta in Canada and from New England to Georgia and Arkansas, and west to Dakota in the United States.
The European Pharmacopoeia prescribes that the herbal drug Polygalae radix can consist of the dried roots of Polygala senega or of certain other closely related species, or a mixture of these Polygala species. There are two main official herbal drug preparations containing Senega root, namely Senega Liquid Extract BP1980 and Concentrated Senega Infusion BP1980; senega extracts are present as an active pharmaceutical ingredient (API) in a number of traditional herbal medicinal products (THRs).
1.4 Common Preparations and Forms
Both species are commercially prepared in multiple forms. Polygala is commonly used in tincture form, where the root is soaked in alcohol to extract its active compounds; the dried root can also be made into a powder or capsule for easier consumption; some traditional preparations include decoctions, where the root is boiled in water to create a concentrated liquid. Polygala tenuifolia is available as a powder or as capsules. In East Asian and Korean markets, a standardized root extract designated BT-11 has been developed and approved as a health functional food ingredient. Based on Ministry of Food and Drug Safety (MFDS) approval, BT-11 is provided as a health functional dietary supplement for helping cognitive function in adults in Korea.
2. Traditional and Historical Use
2.1 Traditional Chinese Medicine (TCM)
The roots of Polygala tenuifolia Willd. (Polygalaceae), which is among the most important components of traditional Chinese herbal medicine, have been widely used for over 1,000 years to treat a variety of diseases. Polygala tenuifolia has been used in Traditional Chinese Medicine and throughout Asia for over 2,000 years, particularly for treating inflammatory diseases, neurasthenia, anxiety-related conditions, and memory.
After 2,000 years of application, the traditional efficacies of Radix Polygalae mainly include calming the heart and tranquilizing the mind, dislodging phlegm and opening the orifices, and detoxifying and reducing swelling. Correspondingly, the classical indications are palpitations, insomnia, restlessness, anxiety, disorientation, forgetfulness, loss of consciousness, cramps, coughing with copious sputum, seizures, swelling, and early stages of ulceration.
Yuan zhi is used primarily as an expectorant; it is one of the 50 fundamental herbs used in traditional Chinese medicine, where it is believed to have neuropsychiatric effects. Senega has been used to aid insomnia, memory impairment, palpitations, coughs, swelling, boils, sores, and pain; in China and Korea, the plant has been used as a tonic, tranquilizer, antipsychotic, neuroprotector, and expectorant.
The related Polygala tenuifolia is used in Chinese medicine to dissolve phlegm that might cause mental and emotional disorders such as nervousness, heart palpitations, insomnia, and anxiety by obstructing the free flow of nutrients, enzymes, and nervous system impulses. In TCM formulation theory, more than 50 prescriptions containing Radix Polygalae have been recorded in ancient medical texts.
In traditional folk medicine, P. tenuifolia has been used for thousands of years as an expectorant and stimulant to treat bronchial asthma, chronic bronchitis, and whooping cough.
2.2 Korean Traditional Medicine
In Korean traditional medicine, Polygala tenuifolia is used as an antipsychotic because it is a serotonin and dopamine receptor antagonist. The herb is known in Korea and Japan as Onji and features prominently in classical East Asian pharmacopoeias, particularly for neuropsychiatric and memory-related applications.
2.3 Native American Traditions (P. senega)
Senegaroot's story starts with North American indigenous tribes like the Cherokee and Iroquois, who valued Polygala senega for treating coughs, asthma, and bronchitis. The native Indians of North America often used this herb to treat snake bites as well as a variety of conditions related to the respiratory system, including pneumonia and pleurisy. The root has been popular in traditional North American herbal medicine where it was used as an expectorant, diuretic, as well as an anti-inflammatory and a medicine to treat toothaches.
The herb became popular in the late 1800s and early 1900s as an effective expectorant and diaphoretic to be used for chronic bronchitis, heavy mucus (catarrh), and asthma. Historical records also mention its use in treating urinary tract infections and as a stimulant for the nervous system.
2.4 European and Western Herbal Medicine (P. senega)
The German Commission E Monographs, a remedial guide to herbal medications, endorse the use of Polygala senega for treating coughs and bronchitis. The Senega root has a secretolytic and expectorant effect; furthermore, antidepressant effects are attributed to the extract; Polygalae radix is used according to Commission E for the treatment of catarrh of the upper airways; further indications according to ESCOP or WHO monograph are chronic bronchitis, productive cough, and emphysema.
Senega root is also used as an ingredient of cough syrups, teas, lozenges, and gargles.
3. Phytochemistry: Key Constituents and Active Compounds
3.1 Overview of Chemical Classes
Phytochemistry studies have shown that various kinds of chemical constituents, including saponins, xanthones, oligosaccharide esters, alkaloids, coumarins, lignans, flavonoids, and other components, are isolated from the genus Polygala. The major components of P. tenuifolia include triterpenoid saponins, xanthone glycosides, phenolic glycosides, and oligosaccharide ester derivatives.
3.2 Saponins
Among these, saponins belong to pentacyclic triterpenoid saponins, and the nucleus is oleanolic acid, which are the main components in the genus Polygala. Most Polygala saponins are unstable in nature and can be hydrolyzed easily to generate polygallic acid, polygalagenin, senegenin, tenuifolin, and various glycosyl groups.
Key identified saponins include onjisaponins (A, B, E, F, G, J, Fg), tenuifolin, senegenin, and polygalasaponin XXXII (PGS32). Saponin compounds (onjisaponins A, B, E, F, and G) from the roots of P. tenuifolia have been used to treat psychosis, whereas xanthone constituents were found to inhibit neuraminidases from influenza A viruses.
For P. senega, the active constituents believed to be responsible for the therapeutic properties of the herbal drug are saponins; a complex mixture of bidesmosidic saponin glycosides have been identified in the root of P. senega which are based on the aglycone presenegenin.
3.3 Oligosaccharide Esters
A distinctive chemical class in P. tenuifolia is the oligosaccharide esters, which include 3,6′-disinapoyl sucrose (DISS), tenuifoliside A, B, and C, and related sucrose derivatives. Identified constituents include onjisaponin J, onjisaponin Fg, onjisaponin B, sibiricose A3, A5, A6, tenuifoliside A, tenuifoliside B, tenuifoliside C, 3,6′-disinapoyl sucrose ester, polygalatenoside A, polygalaxanthone III, polygalaxanthone IV, 7-O-methylmangiferin, 3,4,5-trimethoxyxanthone, tenuiphenone B, hydrocotoin, p-hydroxybenzoic acid, 3,4,5-trimethoxycinnamic acid methyl ester, blumenol C, and 9-epi-blumenol C.
3,6′-disinapoyl sucrose (DISS), a natural compound from Polygala tenuifolia, shows neuroprotective and antidepressant effects, possibly through activation of ERK1/2 and CaMKII pathways; Tenuifoliside A (TFSA), an oligosaccharide ester from Polygala tenuifolia, shows neuroprotective effects on rat glioma cells through the BDNF/TrkB-ERK/PI3K-CREB signaling pathway.
3.4 Xanthones
Polygala species contain several xanthone glycosides. These compounds include polygalaxanthone III, polygalaxanthone IV, and 7-O-methylmangiferin (mangiferin derivative), which have been investigated for anti-inflammatory and neuroprotective properties.
3.5 Alkaloids
Currently, seven β-carboline-based alkaloids have been identified from Polygala Radix; according to studies, β-alkaloids have a large potential for research and use and have properties such as anti-thrombotic, memory improvement, and anti-tumor.
3.6 Organic Acids and Phenylpropanoids
Polygala Radix also includes volatile oils and organic acids; ferulic acid, erucic acid, and 3,4,5-trimethoxycinnamic acid were identified as key active constituents with anticonvulsant, anti-inflammatory, neuroprotective, and anti-amnesic effects.
Polygala Radix also includes coumarins, phenylpropanoids, and inorganic metal elements including zinc, potassium, calcium, copper, iron, and magnesium.
For P. senega, Polygalae radix contains saponins (6 to 10%; common aglycone = presenegine); the main saponin = senegine II and saponin tenuifolin; also polygalic acid, coumaric acid, salicylic acid, methyl salicylate, and oligosaccharides. The presence of methyl salicylate accounts for the characteristic unpleasant odor of dried P. senega root.
4. Mechanisms of Action
4.1 Cholinergic Modulation
One of the most consistently documented mechanisms of P. tenuifolia preparations is inhibition of acetylcholinesterase (AChE), the enzyme responsible for breaking down the neurotransmitter acetylcholine. Results demonstrated that aerial parts of P. tenuifolia (APT) ameliorated learning and memory impairment in scopolamine-induced mice; correspondingly, APT significantly increased ACh and ChAT levels in the hippocampus and prefrontal cortex; additionally, treatment with APT significantly increased BDNF and IL-10 levels, and decreased IL-1β and AChE levels.
4.2 Neurotrophic Factor Upregulation (BDNF and NGF)
Extracts and active ingredients of Radix Polygalae can reduce cell apoptosis by ameliorating neuroinflammation and oxidative stress and can inhibit cell toxicity by regulating BDNF expression, by upstream ERK1/2 pathway, CaMKII activation, and cyclic AMP-responsive element-binding protein (CREB)-mediated BDNF transcription.
A study investigating polygalasaponin XXXII (PGS32), a triterpenoid saponin isolated from the roots of Polygala tenuifolia, used the Morris water maze to evaluate spatial learning and memory; electrophysiological recordings were made of evoked potentials; Western blotting and immunofluorescence assays were used to determine phosphorylation of ERK, CREB, synapsin I, and BDNF expression; when administered at 0.125, 0.5, or 2 mg/kg, PGS32 could significantly prevent scopolamine-induced cognitive impairments in mice. These findings suggest that PGS32 can improve hippocampus-dependent learning and memory, possibly through improvement of synaptic transmission, activation of the MAP kinase cascade, and enhancement of the level of BDNF.
4.3 Glutamatergic and HPA Axis Modulation (Antidepressant Mechanisms)
Radix Polygalae extract can protect against N-methyl D-aspartate (NMDA) neurotoxicity and induce brain-derived neurotrophic factor (BDNF) expression, suggesting modulatory roles at glutamatergic synapses and possible antidepressant action.
Various PR extracts, purified fractions, and several active ingredients (DISS, TEA, etc.) may exert obvious antidepressant effects by inhibiting depression-like behaviors, improving neural cell viability and proliferation, reducing oxidation and apoptosis, and modulating glutamatergic synapses and the HPA axis.
4.4 Anti-inflammatory and Antioxidant Effects
Isolated components from P. tenuifolia roots exhibit diverse pharmacological effects, including anti-inflammatory and anti-diabetic properties. Multiple studies have documented that P. tenuifolia extracts suppress pro-inflammatory cytokines such as IL-1β, reduce malondialdehyde (MDA) levels, and increase superoxide dismutase (SOD) and glutathione (GSH) levels in brain tissue — collectively representing significant antioxidant activity.
4.5 Amyloid-Beta (Aβ) Pathology Modulation
Research studied the effects of Polygala tenuifolia on Aβ(25-35)-induced neuronal damage using rat cortical neurons; treatment with the water extract of PT enhanced axonal length dose-dependently after Aβ(25-35)-induced axonal atrophy.
Furthermore, tenuifolin, isolated from P. tenuifolia roots, showed neuroprotective effects in Aβ25−35 damage-induced PC12 cells in vitro and significantly alleviated cognitive deficits induced by the intrahippocampal injection of Aβ25−35 in mice and APP/PS1 transgenic AD mice models.
4.6 Hippocampal Neurogenesis
A 2021 study investigated the effects of three active constituents — 3,6′-disinapoyl sucrose (DISS), onjisaponin B (OB), and tenuifolin (TEN) — of Polygala tenuifolia (PT) on the proliferation and differentiation of neural stem cells (NSCs) to identify the potential active constituent of PT promoting hippocampal neurogenesis.
4.7 Expectorant Mechanism (P. senega)
The root of P. senega has a stimulating effect on the bronchial mucosa and helps to expel phlegm from the lungs; the herb's anti-inflammatory, antitussive, and expectorant effects are probably due to the saponins and methyl salicylate; the herb has the general ability to stimulate secretion, which also applies to saliva and sweat secretion.
5. Scientific Evidence by Health Area
5.1 Cognitive Function and Memory
Preclinical (Animal) Evidence
A substantial body of preclinical research — mostly conducted in rodent models — has investigated the cognitive-enhancing effects of P. tenuifolia. The root of Polygala tenuifolia has been commonly used in some Asian countries as a memory enhancer and its memory improvement has been reported in various animal models; however, there is less research to verify its effect on memory functions in aged animals.
One study directly addressed this gap: the memory-enhancing effects of the crude extract of Polygala tenuifolia (EPT) on normal aged mice were assessed by Morris water maze (MWM) and step-down passive avoidance tests; in MWM tests, the impaired spatial memory of the aged mice was partly reversed by EPT (100 and 200 mg/kg; P < 0.05); in step-down tests, the nonspatial memory of the aged mice was improved by EPT (100 and 200 mg/kg; P < 0.05).
Another study investigated the ameliorating effect of the aerial part of P. tenuifolia on d-galactose/NaNO2-induced learning and memory impairment in mice; d-galactose (120 mg/kg) and NaNO2 (90 mg/kg) were injected intraperitoneally for 60 days to induce impairment; the aerial part of P. tenuifolia (25, 50, and 100 mg/kg) and piracetam (200 mg/kg) were simultaneously administered orally on days 15–60; results showed that the aerial part can ameliorate learning and memory impairments by modulating cholinergic activity, inhibiting neuroinflammation and oxidative stress, and regulating BDNF and TrkB expression.
Limitation: The preclinical evidence, while mechanistically compelling, is almost entirely from rodent models, limiting direct extrapolation to humans.
Human / Clinical Evidence
Polygala tenuifolia extract enhanced word recognition and recall and improved the overall scores in a mental cognitive test battery in aging adults, showing effects comparable to placebo (Shin et al., 2009; Wang et al., 2019). This reflects the limited and mixed nature of existing human data.
The most clinically relevant human evidence concerns the standardized root extract BT-11. In animal and human studies, the root extract of Polygala tenuifolia Willdenow (BT-11) improved cognitive function significantly; BT-11 also showed anticholinesterase, neuroprotective, and antioxidative efficacies in toxin-induced disease models of animal and cell. Clinical studies in normal adults including the elderly did not show any considerable adverse effects during repeated oral administrations of BT-11 at a dose of 300 mg.
Evidence strength: Human clinical trial evidence for P. tenuifolia alone as a cognitive enhancer is limited and preliminary. Results from small trials are mixed, and most favorable data come from multi-herb combination formulas.
5.2 Alzheimer's Disease
Preclinical Evidence
RP extracts and their active ingredients (polygalacic acid, tenuifoliside B, tenuifolin, fallax saponin A, and senegenin) may improve learning, memory, and cognitive functions; alleviate cognitive impairments; ameliorate neuroinflammation; inhibit oxidative stress; and reduce Aβ secretion and neuronal apoptosis — findings that show the excellent prospects of RP for treating AD.
Polygala tenuifolia is used in a variety of Chinese medicine prescriptions for classic dementia treatment, and polysaccharide is an important active component in the herb; one study investigated the in vivo anti-Alzheimer's disease (AD) activity of the polysaccharide PTPS from Polygala tenuifolia using the senescence-accelerated mouse/prone8 (SAMP8) model.
Clinical Evidence
The most substantive clinical evidence comes from a 2024 systematic review and meta-analysis published in Frontiers in Pharmacology. The review, "Polygala tenuifolia and Acorus tatarinowii in the treatment of Alzheimer's disease: a systematic review and meta-analysis," noted that among Chinese herbal formulas for AD treatment, Polygala tenuifolia (PT) and Acorus tatarinowii (AT) appeared as the most commonly used herbal pairs in combination; the aim was to evaluate the clinical efficacy and safety of the combination of PT and AT in the treatment of AD.
The review systematically searched and screened randomized controlled trials of pairing PT and AT for AD patients in eight databases; primary outcomes assessed included mini-mental state examination (MMSE), activities of daily living (ADL), and AD assessment scale-cognitive subscale (ADAS-cog); the quality of included studies was assessed using the Cochrane risk of bias tool.
The combination of PT and AT plus conventional drugs was superior to single conventional drugs in MMSE [MD = 2.57, 95%CI: (1.44, 3.69); p < 0.00001; I² = 86%], ADL [MD = −3.19, 95%CI: (−4.29, −2.09); p < 0.00001; I² = 0%], and ADAS-cog scores; the combination had a significantly more favorable benefit in clinical effectiveness [RR = 1.27, 95%CI: (1.12, 1.44); p = 0.0002]; adverse events were not increased with the combination compared to conventional drugs.
Critical limitation: In the detailed assessment, 11 studies were assessed to be at low risk during randomization, and the remaining five studies were assessed to be at unknown risk; regarding blinding of participants and personnel, all studies were assessed as high risk; the allocation of the remaining studies was unclear in terms of concealment of allocation, the blinding method, and trial implementation. The high heterogeneity (I² = 86%) in MMSE outcomes further cautions against definitive conclusions. Additionally, all trials examined a combination herb formula (PT+AT), not P. tenuifolia in isolation, making it impossible to attribute effects to P. tenuifolia alone.
5.3 Depression and Mood
Radix Polygalae (RP) and its component DISS (3,6′-disinapoyl sucrose) showed antidepressant-like effects in chronically mild stressed (CMS) animals.
A 2014 PMC study provided preclinical evidence for a rapid-onset antidepressant mechanism. Radix Polygalae extract demonstrated antidepressant-like effects in 8-week-old male C57Bl/6 mice by decreasing behavioral despair in the forced swim and tail suspension tasks and increasing hedonic-like behavior in the female urine sniffing test 30 minutes after a single oral administration of 0.1 mg/kg; reduced latency to acquire a food pellet in the novelty suppressed feeding paradigm, without change in anxiety-like behaviors, suggested a rapid-onset nature of the antidepressant-like effect.
These findings serve as preclinical evidence that Radix Polygalae extract exerts rapid-onset antidepressant effects by modulating glutamatergic synapses in critical brain circuits of depression and may be worthy of further evaluation as a safe substitute to other rapid-onset antidepressants known to have unacceptable side effects.
YZ-50 is an active fraction obtained from the root of Polygala tenuifolia Willd. extract and it has been reported previously to exert beneficial effects on mental health in depressed sufferers; the chronic mild stress (CMS) model of depression in Sprague-Dawley rats was used to evaluate the effects of YZ-50 on depressive behaviors; the capacity of YZ-50 to reverse the harmful effects of CMS was related to the hypothalamo-pituitary-adrenal (HPA) system and BDNF in the hippocampus.
Evidence strength: Evidence for antidepressant effects of P. tenuifolia is preclinical only (animal models). No peer-reviewed, independent, randomized controlled trials in human populations have been identified that specifically evaluate P. tenuifolia alone for depression.
5.4 Anxiety and Sleep
The multifold mechanisms of action include antioxidant and associated apoptotic effects, and anti-inflammatory effects; however, the potential mechanisms of anxiolytic-like and anticonvulsant effects have been less frequently reported and remain unclear. Animal studies have documented anxiolytic-like behaviors following administration of P. tenuifolia root extracts and specific fractions such as tenuifolin and polygalasaponins. No human clinical trials specifically focused on anxiety as a primary outcome for P. tenuifolia alone have been located in the peer-reviewed literature.
5.5 Neuroprotection in Parkinson's Disease
PS-F (polygalasaponin F) protects against rotenone-induced apoptosis in PC12 cells, indicating potential therapeutic properties for treating Parkinson's disease. Based on the reported biological and pharmacological activities of P. tenuifolia, it can be argued whether it could be useful in the prevention and/or treatment of Parkinson's disease, which shares with AD aspects such as neuroinflammation.
Evidence strength: Entirely preclinical (cell and animal). No human data available.
5.6 Respiratory Conditions (P. senega)
Polygalae radix is used according to Commission E for the treatment of catarrh of the upper airways; further indications according to the ESCOP or WHO monograph are chronic bronchitis, productive cough, and emphysema.
Senega has been traditionally used as an antitussive and has also demonstrated hypoglycemic, immunologic, and anticancer effects; however, there are no clinical trials to support these uses.
Evidence strength: The Commission E endorsement and traditional use for respiratory conditions represents a European regulatory acknowledgment of traditional evidence. However, rigorous modern randomized clinical trials specifically for P. senega as an expectorant are lacking; the endorsement is based primarily on longstanding traditional use and plausible pharmacological mechanisms.
5.7 Anti-inflammatory Properties
The roots of Polygala tenuifolia have been widely used for over 1,000 years to treat a variety of diseases; phytochemical investigation led to the isolation of 15 compounds from the roots — divided into two groups: phenolic glycosides and triterpenoid saponins — with anti-inflammatory properties from Korean medicinal plants. These findings remain at the in vitro and animal level.
5.8 Anticancer Activity
Polygala tenuifolia compounds suppressed tumor growth in mice; they also killed human ovarian and lung cancer cells; however, the safety profile of Polygala tenuifolia is relatively unknown, given the lack of well-designed clinical studies. All anticancer evidence is preclinical; no human trials have been conducted.
6. Body Systems and Health Areas of Association
- Central Nervous System: Cognitive function, memory, neuroprotection against Alzheimer's and Parkinson's disease pathology, neurogenesis, synaptic plasticity, depression, anxiety, sleep disturbance, and psychosis (TCM tradition).
- Respiratory System: Productive cough, chronic bronchitis, bronchial asthma, whooping cough, and emphysema — primarily associated with P. senega and endorsed by German Commission E, ESCOP, and WHO monographs.
- Cardiovascular System: Traditional use as a cardiotonic; TCM theory links P. tenuifolia to "heart qi" regulation (palpitations, anxiety). Some saponins have demonstrated anti-thrombotic properties in vitro.
- Immune System: Saponins isolated from Polygala senega L. had potential vaccine adjuvant activity, increasing specific immune responses in mice immunized with ovalbumin and hens immunized with rotavirus.
- Skin and Topical: Traditional use for boils, sores, swelling, and as a gargle and mouthwash for catarrhal conditions.
7. Dosage Forms and Dosages Reported in Studies
The following dosages are drawn directly from cited clinical or preclinical sources. They are reported as stated in those sources and should not be interpreted as dosing recommendations.
- BT-11 (Standardized Root Extract, Clinical Trials — Adults):
Clinical studies in normal adults including the elderly did not show any considerable adverse effects during repeated oral administrations of BT-11 at a dose of 300 mg.
- BT-11 (Clinical Safety Study — Adolescents):
The safety was evaluated in randomly assigned subjects who received the test products (61 subjects in BT-11 300 mg daily or 60 subjects in matching placebo) for 12 weeks.
- Clinical Trials (General Dosage Pattern Reported):
In clinical trials, it was administered as 100 mg per dose, 3 times a day.
- Animal Preclinical (Aged Mice, Crude Extract):
The impaired spatial memory of the aged mice was partly reversed by EPT at 100 and 200 mg/kg.
- Animal Preclinical (Aerial Part):
Mice were orally administered APT (25, 50, and 100 mg/kg) and piracetam (750 mg/kg) for 14 days, and intraperitoneally injected with scopolamine (2 mg/kg) from days 8 to 14.
- Animal Preclinical (PGS32 Isolated Saponin):
When administered at 0.125, 0.5, or 2 mg/kg, PGS32 could significantly prevent scopolamine-induced cognitive impairments in mice.
- Animal Preclinical (Antidepressant RP Extract):
Radix Polygalae extract demonstrated antidepressant-like effects 30 minutes after a single oral administration of 0.1 mg/kg.
8. Safety, Toxicology, and Interactions
8.1 Preclinical Toxicology
Acute oral toxicity was tested in both rats and dogs; in the rats, only one female of 2 g/kg died, but no treatment-related death or clinical and gross findings were observed after the administration; no toxicological changes or mortalities related to the test substance were also observed after the administration in the dogs.
The no-observed-adverse-effect level was determined at 1,000 mg/kg, p.o., through acute and repeated toxicity studies in rats and dogs.
Results showed that the acute or subchronic toxicity of the root extract of Polygala tenuifolia might not be toxic to rats and dogs.
With respect to genotoxicity, a bone marrow micronucleus test in ICR mice dosed by oral gavage at doses up to 2,000 mg/kg/day showed no significant or dose-dependent increase in the frequency of micronucleated polychromatic erythrocytes. However, there is no sufficient background information on toxicological evaluation of the root to give an assurance of safety for developing dietary supplements and functional foods; as part of a safety evaluation, the potential genotoxicity of the root extract of P. tenuifolia was evaluated using a standard battery of tests (bacterial reverse mutation assay, chromosomal aberrations assay, and mouse micronucleus assay).
8.2 Clinical Safety Data
The safety evaluation in randomly assigned subjects (61 subjects in BT-11 300 mg daily or 60 subjects in matching placebo) for 12 weeks included analysis of adverse reactions by incidence rate, type, and severity; clinical examination included hematology and blood chemistry tests, urinalysis, vital signs, body weight, and electrocardiogram (ECG); eleven adverse reactions were observed in ten subjects receiving BT-11 while seven adverse reactions in six subjects receiving placebo. This difference was not considered significant by the authors.
The safety profile of Polygala tenuifolia is relatively unknown, given the lack of well-designed clinical studies.
8.3 Gastrointestinal Effects (High Dose)
Senega can be toxic in high doses, particularly due to its saponin content, which can cause gastrointestinal irritation, nausea, vomiting, and diarrhea. Although vomiting, discoloration, or hemorrhage was found in some dogs in acute toxicity testing at high doses, there were no serious abnormalities.
8.4 Contraindications and Special Populations
The bark of Polygala senega L. is used in some traditional preparations to induce abortion or cause miscarriage, which raises significant concerns regarding use in pregnancy. Given this traditional abortifacient use and the lack of systematic safety data in pregnant women, the herb is generally avoided in pregnancy. For pregnant or breastfeeding women, insufficient data exist, so Polygala senega is best avoided or used only under professional guidance.
8.5 Drug Interactions
This suggests that Polygala tenuifolia could interact with other medications and affect their metabolism. The β-carboline alkaloids identified in Radix Polygalae have monoamine oxidase inhibitory (MAOI) activity, which raises the theoretical possibility of interactions with serotonergic or adrenergic medications and dietary tyramine. However, the clinical significance of this has not been formally evaluated in human pharmacokinetic trials. The saponin content of P. senega may also alter absorption of co-administered drugs through its surfactant and membrane-permeabilizing properties.
8.6 Quality Concerns
The quality of the herb varies widely. Adulteration and substitution between related Polygala species is documented in the traditional medicine trade, and the phytochemical profile can vary significantly depending on growing region, harvesting season, and processing method.
9. Regulatory and Pharmacopoeial Status
- China: Polygala tenuifolia is officially listed in the Chinese Pharmacopoeia Commission, 2015.
- Korea: Based on Ministry of Food and Drug Safety (MFDS) approval, BT-11 (root extract) is provided as a health functional dietary supplement for helping cognitive function in adults in Korea.
- Europe (P. senega): Polygalae radix is used according to Commission E for the treatment of catarrh of the upper airways; further indications according to ESCOP or WHO monograph are chronic bronchitis, productive cough, and emphysema.
- European Pharmacopoeia: The European Pharmacopoeia prescribes that the herbal drug Polygalae radix can consist of the dried roots of Polygala senega or of certain other closely related species, or a mixture of these Polygala species; there are two main official herbal drug preparations: Senega Liquid Extract BP1980 and Concentrated Senega Infusion BP1980.
10. Summary of Evidence Strength
- Respiratory expectorant use (P. senega): Supported by Commission E, ESCOP, and WHO monographs based on traditional use and plausible mechanistic rationale. No modern RCTs.
- Cognitive function / memory in aging: Encouraging preclinical data; limited, mixed, and methodologically weak human evidence. The BT-11 extract has been evaluated in some human studies, but independent, large-scale RCTs are lacking.
- Alzheimer's disease (combination with Acorus tatarinowii): 2024 meta-analysis shows positive outcomes on MMSE, ADL, and ADAS-cog vs. conventional drugs alone, but all trials were at high risk of bias for blinding, and high heterogeneity limits conclusions. Evidence is considered preliminary.
- Antidepressant effects: Preclinical evidence only (rodent models). Mechanistically plausible via glutamatergic and HPA axis modulation. No human RCTs identified.
- Anxiolytic and neuroprotective effects: Preclinical; mechanisms partly elucidated but human evidence absent.
- Anticancer properties: Cell and animal data only; no clinical relevance established.
References
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