Bupleurum (Radix Bupleuri): A Comprehensive Reference
1. Identity: Botanical Names, Natural Source, and Common Forms
Radix Bupleuri is obtained from the root of Bupleurum chinense DC., which belongs to the Umbelliferae (Apiaceae) family; it typically grows mainly in the subtropical regions of the Northern Hemisphere. More than 20 species of the genus Bupleurum have been described, including a toxic species, Bupleurum longiradiatum, found in northeast China, and Bupleurum kaoi, which is indigenous to Taiwan. The root of B. chinense DC. is considered the genuine Chaihu, but other species have been included in the Pharmacopoeia of the People's Republic of China since 1963, including bei Chaihu and nan Chaihu (referring to northern and southern thorowax root). B. falcatum is used in Japan. Confusion exists regarding the species B. scorzonerifolium Willd., which may be the same as B. falcatum L. var scorzonerifolium.
B. chinense and B. scorzonerifolium are officially listed in the Pharmacopoeia of the People's Republic of China and are recognized as "North Bupleurum" and "South Bupleurum" respectively for their common names based on their different distributions. Bupleurum falcatum L. is officially listed in the Japanese Pharmacopoeias, as well as WHO monographs on selected medicinal plants in China and Korea.
Common names for Bupleurum and its root preparations include several that reflect its multicultural use. Some common names of this herb include chai hu, hare's ear root, thorowax root, and saiko. Radix Bupleuri is the dry root of Bupleurum chinense DC. (Apiaceae) and Bupleurum scorzonerifolium Willd.
Common Preparations and Dosage Forms
The roots are usually the medicinal parts of Radix Bupleuri, and they are often processed into pieces for easy use. In modern supplement and clinical contexts, typical dosages are 100–500 mg once or twice daily, but Bupleurum species are often combined at 50–200 mg in multi-herb formulas taken once or twice daily. Bupleurum is sold in multiple forms, including dried root pieces for decoction, standardized powdered root extracts in capsule or tablet form, concentrated liquid extracts, tinctures, and as an ingredient in standardized combination formulas. A variety of chemical constituents have been isolated and identified from the species in Bupleurum L., and the herb is used in products ranging from raw dried root to concentrated extracts.
2. Traditional and Historical Use
Traditional Chinese Medicine (TCM)
With a 2,000-year medicinal history, Radix Bupleuri (Chai Hu in Chinese) is believed to be one of the most important herbal medicines in China. The earliest record about Radix Bupleuri in China appeared in Shen Nong Ben Cao Jing, the first Chinese medical book; since then, Radix Bupleuri has been widely used in traditional Chinese medicine (TCM) for its effects of relieving exterior syndrome, clearing heat, regulating the liver-qi, and lifting yang-qi. It has been used in many traditional Chinese prescriptions, such as Xiao Chai Hu Tang and Chai Hu Shu Gan Yin, to treat cold and liver diseases.
The root of various Bupleurum species (B. chinense, B. falcatum) are well-known as medicinal plants in China and are listed in the oldest Chinese materia medica documents, the Shennong's Herbal. Bupleurum was described as having the action of "soothing liver and relieving constraint," useful for improving both frank liver symptoms and improving emotional instability such as depression, anxiety, and phobia.
In TCM, it is primarily utilized for the treatment of colds, fevers, imbalances in cold and heat, and stagnation of liver qi. Historically, both the roots and aerial parts of B. scorzonerifolium have been extensively utilized to treat a variety of ailments, such as fever, liver disorders, inflammatory conditions, and emotional imbalances such as depression.
The Classic Formula Xiao Chai Hu Tang
Bupleurum has a recorded history of use that dates to around 200 A.D., with its first recorded medicinal use appearing in the Treatise on Cold Induced Febrile Disease, a Chinese medical text that dates to the close of the Eastern Han Dynasty in the 3rd century AD. One of the 269 formulas in this book is Xiao Chai Hu Tang, an ancient Chinese remedy designed to harmonize shaoyang. This same formula, which combines Bupleurum with licorice, ginger, ginseng, Chinese skullcap, and peony root, is also known as the Japanese Kampo medicine Sho-Saiko-To. In Japan, this is the primary traditional treatment for hepatitis and liver disease.
Japanese Kampo Medicine
Bupleurum is a traditional Chinese herb dating back to the first century BC and is one of the most commonly used herbs in traditional Chinese medicine. It forms an integral part of many Kampo medicines (the Japanese adaptation of traditional Chinese medicine), including shosaikoto, daisaikoto, saikokeishito, hochuekkito, saibokuto, and saireito. Bupleurum makes up 16% of the formula for sho-saiko-to.
In both traditions, Bupleurum-containing formulas were prepared primarily as decoctions (boiled water extracts), though powders and pills were also recorded in classical texts. Sho-saiko-to is used in both China and Japan as traditional medicine to treat fever, gastrointestinal disorders, chronic liver diseases, and inflammatory conditions.
3. Key Constituents and Active Compounds
After chemical profiling, several groups of secondary metabolites have been characterized with relevant biological activity: triterpene saponins (saikosaponins), lignans, essential oils, and polysaccharides. A variety of chemical constituents have been isolated and identified from the species in Bupleurum L., such as saikosaponins, polysaccharides, volatile oils, flavonoids, polyacetylenes, lignins, and coumarins, most of which possess a variety of biological activities, especially for the hepatoprotective effect, antitumor activity, immunoregulation, and febrifuge efficacy.
Saikosaponins
Saikosaponins comprise a large group of chemical components present in the Bupleurum species that have attracted attention in the field of medicine because of their significant biological activities. All of the potent effects attributed to this herb are due to its various secondary metabolites, especially saikosaponins, the content of which is up to 7% of the total dry weight of Radix Bupleuri roots. To date, over 100 glycosylated oleanane-type saponins have been isolated and identified from Radix Bupleuri. The most pharmacologically studied saikosaponins are designated saikosaponin a (SSa), saikosaponin b2 (SSb2), saikosaponin c (SSc), and saikosaponin d (SSd).
Saikosaponins, the main active constituents of Bupleurum spp., have been shown to possess immunomodulatory, hepatoprotective, anti-tumor, and anti-viral activities. Among these, SSa has the strongest anti-inflammatory effect, and SSd possesses the strongest antitumor effect compared with other saikosaponins, and both SSb2 and SSc have better antiviral activity.
Saikosaponin D (SSD) is a triterpene saponin with a steroid-like structural framework. Its chemical formula is C₄₂H₆₈O₁₃, with a molecular weight of 780.98 g/mol.
Polysaccharides
Rare monosaccharides, like ribitol, xylose and arabinose, and pectic polysaccharides, like bupleuran 2IIb and bupleuran 2IIc, have been isolated from B. falcatum and many other species; these compounds exert anti-ulcer, anti-inflammatory, anti-infective, and immunomodulatory effects in autoimmune diseases.
Lignans and Other Compounds
Present interest is also focused on the anti-proliferative activity of different lignans found in Bupleurum species. Free organic and fatty acids, like pinellic acid, angelic acid, petroselic acid, and lignoceric acid, have also been identified in many species. The active phytochemicals in Bupleurum species include saponins, sterols, coumarins, flavonoids, lignans, polysaccharides, and essential oils.
Essential Oils
Essential oil composition in Bupleurum varies by species. Chemical analysis of B. rigidum subsp. paniculatum showed that its essential oil is characterized by the presence of high amounts of monoterpene hydrocarbons (94.4–96.6%), mainly α-pinene (29.0–36.0%), β-pinene (26.1–30.7%) and limonene (10.5–13.5%).
4. Established Mechanisms of Action
Anti-inflammatory Pathways
Saikosaponin A (SSA) markedly inhibits the expression of certain immune-related cytotoxic factors, including cyclooxygenase-2 (COX-2) and inducible nitric-oxide synthase (iNOS), as well as pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6. It also significantly upregulates the expression of IL-10, an important anti-inflammatory cytokine.
SSA inhibits the activation of the nuclear factor-κB (NF-κB) signaling pathway by suppressing the phosphorylation of inhibitory NF-κB inhibitor α (IκBα), thus holding p65 NF-κB in the cytoplasm to prevent its translocation to the nucleus. In addition, SSA also inhibits the mitogen-activated protein kinase (MAPK) signaling pathway by downregulating the phosphorylation of p38 MAPK, c-Jun N-terminal kinase (c-JNK) and extracellular signal-regulated kinase (ERK), the three key components of the MAPK family.
Both SSa and SSd significantly inhibited the expression of inducible nitric-oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-induced cells, resulting in the reduction of nitric oxide (NO) and prostaglandin E2 (PGE2). LPS-induced production of major pro-inflammatory cytokines—TNF-α and IL-6—was suppressed in a dose-dependent manner by the treatment of SSa or SSd.
In screening for in vitro effects of saikosaponins on cellular systems generating cyclooxygenase (COX) and lipoxygenase (LOX) metabolites, most saikosaponins showed a significant effect. The action is more marked on LOX metabolite LTC4.
Hepatoprotective Mechanisms
The therapeutic effect of saikosaponin D on liver fibrosis and cirrhosis has been evaluated. The results clearly demonstrated that saikosaponin D significantly reduced collagen I deposition in the liver. Moreover, it reduced the concentration of transforming growth factor β1 (TGF‐β1) in the liver, which is used as a key marker for liver fibrosis.
Antiviral Activity
HBV-transfected human hepatoma cells cultured with saikosaponin c showed a significantly lower level of HBeAg in culture medium. Saikosaponin c also possessed activity in inhibiting HBV DNA replication; this inhibitory effect was not due to cytotoxicity of saikosaponin c or its effect on cell proliferation.
Antitumor Mechanisms
The antitumor effects of saikosaponin D (SSD) are multi-targeted and can be realized through various mechanisms, including inhibition of proliferation, invasion, metastasis, and angiogenesis, as well as induction of cell apoptosis, autophagy, and differentiation. In cancer research, saikosaponins exhibit chemosensitisation effects when used in combination with conventional agents, in part by promoting reactive oxygen species (ROS)-mediated apoptosis.
Neuroprotective and Antidepressant Mechanisms
Biochemical assays revealed that SSA normalized levels of neurotransmitters (5-HT, DA, and 5-HIAA), enhanced antioxidant enzyme activity (SOD, CAT, and GSH), and suppressed neuroinflammatory cytokine production (TNF-α, IL-1β, and IL-6). Mechanistically, SSA exerted its antidepressant effects by inhibiting the TLR4/NF-κB signaling pathway and upregulating BDNF expression. SSA has also been shown to rescue perimenopausal depression-caused behavioral deficits by inhibiting the activation of the HPA axis, relieving neuroinflammation, and increasing BDNF expression.
5. Scientific Evidence by Area of Use
5.1 Liver Disease and Hepatoprotection
Preclinical evidence: In laboratory and animal studies, Sho-saiko-to appears to prevent liver injury, reduce inflammation, and stimulate or enhance immune functioning. Active components are likely to be saikosaponins and the antioxidants baicalin and baicalein, which resemble silibinin.
Human/clinical evidence: Human trials, only one double-blind, have shown that the bupleurum-containing formula sho-saiko-to may help reduce symptoms and blood liver enzyme levels in children and adults with chronic active viral hepatitis. Most of these studies were in people with hepatitis B infection, though one preliminary human trial has also shown a benefit in people with hepatitis C. Sho-saiko-to was also found, in a large, preliminary (but not double-blind) study, to decrease the risk of people with chronic viral hepatitis developing liver cancer. One randomized trial found that sho-saiko-to could reduce the rate of liver cancer in people with liver cirrhosis.
Evidence quality: A meta-analysis determined that the efficacy of Sho-saiko-to for chronic hepatitis B is unclear, with small trials of low methodological quality. Only a few clinical trials have been conducted in humans. These studies suggest it may be helpful for some types of patients with hepatitis, but studies to confirm this are needed. A critical limitation is that results reported for sho-saiko-to cannot be attributed solely to bupleurum, because the other herbs in the formula also contribute. Robust, adequately powered, double-blind controlled trials are absent.
Although bupleurum is used in traditional Chinese medicine to treat liver diseases, human data are lacking for bupleurum used as a single ingredient.
5.2 Inflammation
Preclinical evidence: A broad spectrum of in vitro and in vivo research has proved that Radix Bupleuri extracts, saikosaponin a, saikosaponin d, saikosaponin c, and saikosaponin b2, exhibit evident anti-inflammatory, antitumor, antiviral, anti-allergic, immunoregulation, and neuroregulation activities, mainly through NF-κB, MAPK, or other pathways.
Human/clinical evidence: Controlled human clinical trials specifically evaluating bupleurum's anti-inflammatory effects as a standalone ingredient are currently absent. The mechanistic anti-inflammatory evidence derives from cell-culture (in vitro) and animal models. Further investigations and screenings are required to explore other Bupleurum species, to evaluate clinical safety and possible interactions with other drugs or herbs.
Evidence quality: Preclinical (in vitro and animal studies) only; no human clinical trials targeting inflammatory outcomes with isolated bupleurum extracts.
5.3 Depression and Neuropsychiatric Conditions
Preclinical evidence: Total saikosaponins (TSS) at doses of 25 and 50 mg/kg decreased immobility time in the forced swim test. TSS at 25 mg/kg showed antidepressant-like and anxiolytic effects in the chronic corticosterone treatment model in mice. TSS increased hippocampal synaptic proteins (synapsin-1 and postsynaptic density protein 95) expression.
In a mouse model of chronic unpredictable mild stress (CUMS)-induced depression, mice received daily administration of SSA (20 mg/kg, orally, for 6 weeks). Behavioral tests, including tail suspension test, open field test, elevated plus maze, and marble burying test, indicated that SSA significantly alleviated depressive-like and anxiety-like behaviors. Histopathological analysis showed that SSA reduced hippocampal neuronal damage induced by chronic stress.
Saikosaponin-d (SSd) is a triterpene saponin from the roots of Bupleurum chinense. Recent studies have revealed its antidepressant activity, but its mechanism is unclear.
Evidence quality: All evidence for antidepressant activity is from preclinical (animal and cell) studies only. Although these studies highlight SSA's antidepressant potential, its precise molecular targets and underlying mechanisms remain unclear. No human clinical trials are available for bupleurum as a standalone treatment for depression.
5.4 Antiviral Activity
Preclinical evidence: Saikosaponin c significantly lowered HBeAg levels and inhibited HBV DNA replication in HBV-transfected human hepatoma cells in vitro. Saikosaponin d exhibited cytotoxicity on hepatoma cells and induced apoptosis through the activation of caspases 3 and 7.
Human/clinical evidence: Bupleurum may have antiviral activity, but clinical trials have not been conducted.
Evidence quality: In vitro only; no human antiviral trials for bupleurum as a standalone agent.
5.5 Cancer and Antitumor Effects
Preclinical evidence: Bupleuri Radix, the dried root of Bupleurum chinense DC. and Bupleurum scorzonerifolium Willd., is widely used to treat cancers for hundreds of years in Asian countries. As the most antitumor component but also the main toxic component in Bupleuri Radix, saikosaponin D (SSD) has attracted extensive attention. Experiments suggest bupleurum might exert some influence over multidrug resistance in drug-resistant cells. Saikosaponins, a major constituent, enhanced cisplatin cytotoxicity against solid tumors.
Human/clinical evidence: SSD is a potentially effective and relatively safe natural antitumor substance, but more research is needed, especially regarding in vivo antitumor effects and pharmacokinetics. No standalone bupleurum clinical trials in cancer patients are available; the relevant context is its role within combination formulas.
Evidence quality: Preclinical only; in vitro and animal data only. No human oncology trials for bupleurum as an isolated ingredient.
5.6 Immunomodulation
Preclinical evidence: Present interest is focused on the bioactivity of the isolated triterpene saponins acting as immunomodulatory, anti-inflammatory, and antiviral agents, as well as on the observed anti-ulcer activity of the polysaccharides. Many saikosaponins exhibited very potent anti-inflammatory, hepatoprotective, and immunomodulatory activities both in vivo and in vitro.
Preclinical studies suggest that bupleurum has antiviral, hepatoprotective, anti-inflammatory, immune-modulating, antiproliferative, and chemopreventive properties.
Evidence quality: Largely preclinical. The polysaccharide fractions (bupleuran 2IIb, bupleuran 2IIc) have shown immunomodulatory effects in animal models, but controlled human trials are lacking.
5.7 Fever Reduction (Antipyretic)
Bupleurum has a long TCM history as an antipyretic. Although bupleurum is used in traditional Chinese medicine to reduce fever, there are no clinical data to back this claim. Pharmacological studies have confirmed that Radix Bupleuri exhibits antipyretic effects in preclinical settings, but controlled human trials are absent.
6. Body Systems and Health Areas
Based on the available scientific literature, Bupleurum has been investigated in relation to the following body systems and health areas:
- Hepatic/Biliary system: Bupleurum is widely used in China and other Asian countries to manage chronic liver inflammation and viral hepatitis. Preclinical and limited clinical data relate to hepatitis, liver fibrosis, cirrhosis, and hepatocellular carcinoma prevention.
- Immune system: After chemical profiling, several groups of secondary metabolites were characterized with relevant biological activity. Present interest is now focused on the bioactivity of the isolated triterpene saponins acting as immunomodulatory, anti-inflammatory, and antiviral agents.
- Central nervous system: Bupleurum has long been used in traditional Chinese medicine to treat various psychiatric disorders, including depression. Preclinical models have examined its effects on anxiety and depression via neurotransmitter and neuroinflammatory mechanisms.
- Gastrointestinal system: The anti-ulcer activity of the polysaccharide fractions has been studied preclinically.
- Cardiovascular/Hematological system: Antiaggregating effects on platelets by the lactone bupleurumin (extracted from the aerial parts of B. falcatum) have been demonstrated in vitro. Therefore, potentiation of thrombolytic and antiaggregating medicines is theoretically possible.
- Respiratory system: Associated primarily through safety data regarding interstitial pneumonitis risk with formula-based use.
- Endocrine/Adrenal system: Bupleurum is used in combination with Panax ginseng and licorice to help stimulate adrenal gland function, particularly in patients with a history of long-term use of corticosteroid drugs. This use is based on traditional practice; rigorous clinical evidence is lacking.
7. Clinical Preparations and Formulas
Fifteen clinical preparations approved by the China Food and Drug Administration (CFDA) remarkably broaden the application of Radix Bupleuri.
The most extensively researched multi-herb formula containing Bupleurum is Sho-saiko-to (TJ-9). Sho-saiko-to (xiao-chai-hu-tang or minor bupleurum formula) contains the following: Bupleurum falcatum (thorowax) root 16%, Paeonia lactiflora (peony) root 16%, Pinellia ternata (ban xia) rhizome 14%, Cinnamomum cassia (cassia) bark 11%, Zingiber officinale (ginger) rhizome 11%, Zizyphus jujuba (jujube) fruit 11%, Panax ginseng (Asian ginseng) root 8%, Scutellaria baicalensis (Chinese skullcap) root 8%, Glycyrrhiza uralensis (licorice) rhizome 5%.
Sho-saiko-to is widely used in Japan to treat patients with chronic hepatitis. Other significant Kampo formulas containing Bupleurum include daisaikoto, saikokeishito, hochuekkito, saibokuto, and saireito. Preparations include combinations of bupleurum with glycyrrhiza, scutellaria root, ginseng, jujube fruit, astragalus root, magnolia bark, alisma rhizome, and rhubarb.
Although B. chinense and B. scorzonerifolium are the only two original plants of Radix Bupleuri in the Chinese Pharmacopeia, many other Bupleurum species are often used as Radix Bupleuri in China. The extracts of B. chinense, B. falcatum, B. marginatum, B. yinchowense, B. kaoi, B. scorzonerifolium, and B. longiradiatum possess different pharmacological activities.
8. Dosages Reported in Studies
The following dosages appear in the referenced scientific literature and are presented strictly as reported:
- In a CUMS mouse model study, mice received daily administration of SSA at 20 mg/kg, orally, for 6 weeks.
- Dose-response effects of total saikosaponins (TSS) at 12.5, 25, and 50 mg/kg were investigated in the forced swim test in ICR male mice.
- For standalone supplement use in humans, typical dosages reported are 100–500 mg once or twice daily, with multi-herb formulas using 50–200 mg once or twice daily.
- In ongoing clinical trials, physicians administered 7.5 g/day of Sho-saiko-to (granules) for one year to patients with chronic liver disease.
No standardized, universally accepted human clinical dosage has been established for bupleurum as a single-ingredient preparation, owing to the absence of dose-finding clinical trials.
9. Safety Considerations and Interactions
Hepatotoxicity
The main side effect of Radix Bupleuri is liver damage when the dosage is excessive, which indicates that the maximum tolerated dose is critical for clinical use of Radix Bupleuri extract and purified compounds. Despite its hepatoprotective effects, Bupleurum can also exert hepatotoxic effects at a very high dose and duration, and can even induce fatal hepatotoxicity at doses from 50 to 125 g/kg in 1–2 weeks' time in rats. Alcohol extractions of Bupleurum have shown greater hepatotoxicity than water extracts. Possible liver injury in humans has been reported from B. chinense, with anecdotal reports of inducing fibrosis.
Saikosaponins have drawn great attention for their anti-inflammation, anti-viral, and anti-cancer effects, and contradictory roles in the regulation of cell apoptosis, oxidative stress, and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of saikosaponins and Radix Bupleuri have also been reported. However, underlying mechanisms of saikosaponin bioactivities and their metabolism are largely unknown.
Pulmonary Toxicity: Interstitial Pneumonitis
Since 1994, therapy with interferon is contraindicated for Sho-saiko-to; in 1996, the Japanese Ministry of Health issued an official warning of interstitial pneumonia as a side effect.
Interstitial pneumonia has been reported to be a side effect of treatment with interferon, and Sho-saiko-to (Xiao-Chai-Hu-Tang) may enhance this side effect. Sho-saiko-to increased the production of TNF-alpha by monocytes; additionally, Sho-saiko-to significantly increased the production of TNF-alpha by monocytes stimulated by lipopolysaccharide. These data indicate that interferon causes neutrophils to accumulate in the lung. Sho-saiko-to alone may not injure lung tissue, but it increases the effect of interferon.
Using Sho-saiko-to at the same time as interferon treatment can increase the risk of interstitial pneumonitis, a potentially fatal condition. Patients with liver cancer or cirrhosis may also be at risk. Patients with chronic hepatitis and low platelet counts are at particular risk.
The toxicological effects of saikosaponin D (SSD) mainly include hepatotoxicity, neurotoxicity, haemolysis, and cardiotoxicity in preclinical studies, though the clinical significance of these findings at therapeutic doses requires further investigation.
Drug Interactions
Pharmacokinetic studies demonstrated that SSD has the potential to alter the pharmacokinetics of some drugs due to its influence on CYPs and P-glycoprotein, and the oral bioavailability and actual pharmacodynamic substances in vivo of SSD are still controversial.
Saikosaponins antagonized the stimulatory effects of caffeine and methamphetamine in mice; synergism with CNS depressants is theoretically possible. Inhibition of CYP3A4 by aqueous extracts has also been demonstrated.
Antiaggregating effects on platelets by the lactone bupleurumin have been demonstrated in vitro. Therefore, potentiation of thrombolytic and antiaggregating medicines is theoretically possible.
Preclinical studies show that Sho-saiko-to can affect the blood concentrations of drugs metabolized by CYP450 enzymes. One study in healthy humans also suggests it may interact with some drugs, though clinical relevance has yet to be determined.
General Tolerability
Bupleurum has produced mild lassitude, sedation, and drowsiness in some individuals. Large doses have been reported to increase flatulence and bowel movements. Allergy to injected bupleurum has been reported.
Species Toxicity
The extracts of different Bupleurum species possess different pharmacological activities. Because the quality, botanic characteristics and properties, and pharmacological activities of different Bupleurum species are different, the standardization of Bupleuri Radix extracts is vital for the safe use of Radix Bupleuri. More than 20 species of the genus Bupleurum have been described, including a toxic species, Bupleurum longiradiatum, found in northeast China. Correct botanical identification of the species used is therefore essential for safety.
10. Overall Evidence Assessment
Early studies on the genus Bupleurum focused only on the traditional uses of the plants in the treatment of inflammatory disorders and infectious diseases. After chemical profiling, several groups of secondary metabolites were characterized with relevant biological activity: triterpene saponins (saikosaponins), lignans, essential oils, and polysaccharides. Present interest is focused on the bioactivity of the isolated triterpene saponins acting as immunomodulatory, anti-inflammatory, and antiviral agents, as well as on the observed anti-ulcer activity of the polysaccharides and anti-proliferative activity of different lignans. Many saikosaponins exhibited very potent anti-inflammatory, hepatoprotective, and immunomodulatory activities both in vitro and in vivo. Further investigations and screenings are required to evaluate the clinical safety and possible interactions with other drugs or herbs.
In sum, the large majority of evidence for bupleurum's pharmacological effects is preclinical (cell culture and animal models). Limited human clinical data exist almost exclusively for bupleurum-containing combination formulas — most notably sho-saiko-to — rather than for bupleurum as an isolated ingredient. Even for the combination formula, the clinical trial base is small, methodologically variable, and insufficiently powered. The chemical diversity among Bupleurum species, extraction methods, and combination contexts makes generalisation across preparations difficult. Standardisation of preparations and large-scale, rigorous human clinical trials are needed before firm therapeutic conclusions can be drawn.
References
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