Zanthoxylum

Zanthoxylum: A Comprehensive Reference

1. Identity and Taxonomy

Genus and family: Zanthoxylum L. belongs to the family Rutaceae (the citrus family). The genus Zanthoxylum L. is the second largest genus of this family and comprises approximately 225–549 species distributed in the tropical and temperate regions of the world. Plants of this genus are trees and shrubs with various applications in folklore medicine for food, medicine, construction, and other uses.

Synonymy: Zanthoxylum species, also known as Fagara species, have a long history of use as sources of food and drug by locals in different parts of Asia, America and Africa. The older genus name Fagara appears extensively in older ethnobotanical and pharmacological literature and refers to the same set of plants.

Key species of botanical and commercial importance include:

• Zanthoxylum bungeanum Maxim. — Chinese prickly ash, "Hua Jiao" (Sichuan pepper, red variety)
• Zanthoxylum schinifolium Sieb. et Zucc. — green Sichuan pepper ("Qing Hua Jiao")
• Zanthoxylum piperitum (L.) DC. — Japanese pepper ("sansho")
• Zanthoxylum americanum Mill. — northern prickly ash (North America)
• Zanthoxylum clava-herculis L. — southern/Hercules club prickly ash (North America)
• Zanthoxylum zanthoxyloides Lam. — African prickly ash, toothache plant
• Zanthoxylum armatum DC. — winged prickly ash (South and Southeast Asia)
• Zanthoxylum nitidum (Roxb.) DC. — liang mian zhen (East and Southeast Asia)
• Zanthoxylum rhetsa (Roxb.) DC. — Indian ivy-rue

Hua Jiao is a popular food additive and traditional Chinese herbal medicine, which first appeared in the Shennong Ben Cao Jing in the late Western Han Dynasty (around 100 BCE). According to the 2020 edition of the Chinese Pharmacopoeia, a total of three Z. varieties were included, namely Zanthoxylum bungeanum Maxim., Zanthoxylum schinifolium Sieb. et Zucc., and Z. nitidum.

Common forms and preparations: The Zanthoxylum species have a wide use in different parts of the continents as a remedy for various diseases; various parts of the plant comprising fruits, seeds, twigs, roots, root bark, leaves, and pericarps are used. Preparations encountered in the literature and traditional practice include dried whole pericarp (the dominant culinary and medicinal form), decoctions, essential oils obtained by steam distillation, organic solvent extracts, powders, and pastes. Methods for extracting active compounds from Zanthoxylum L. plants include steam distillation, organic solvent extraction, supercritical CO₂ extraction, and others. In supplement and nutraceutical contexts, standardized extracts, capsules, and tinctures are available, though standardization methods vary considerably across commercial preparations.

2. Traditional and Historical Uses

Traditional Chinese Medicine (TCM)

Zanthoxylum bungeanum Maxim., or Chinese prickly ash, holds a rich history spanning over two millennia in traditional Chinese medicine. This herb has been extensively used orally and topically to address various ailments, including gastrointestinal discomfort, arthritis, and bruises. Its significance extends beyond China, finding a place in traditional medical practices in countries such as India and Nepal.

It has been confirmed by traditional Chinese medicine (TCM) research that Zanthoxylum L. plants have the effects of promoting blood circulation and removing blood stasis, promoting qi and relieving pain, dispelling wind and dredging collaterals, detoxifying and reducing swelling, killing insects and relieving itching. It is widely used in the treatment of urinary tract infection, gynecological diseases, vomiting, diarrhea, hernia, stomach pain, toothache, rheumatism arthralgia, abdominal pain, and snake bite. In Traditional Chinese Medicine, Zanthoxylum bungeanum has been used as a herbal remedy. It is listed in the Pharmacopoeia of the People's Republic of China and is prescribed for ailments as various as abdominal pains, toothache, and eczema.

The unique flavor and numbing taste of the dried fruit follicles of Z. bungeanum have made it a significant ingredient in Chinese cuisine. In TCM, the herb is considered thermally "warm" to "hot" in character with a pungent flavor, and is classified as entering the spleen, stomach, and kidney meridians. Traditional TCM dosage for decoction is reported as 3–6 grams of the dried fruit; powder formulations are noted at 500 mg–2 grams per dose in traditional references.

South and Southeast Asian Traditions

Zanthoxylum armatum has been used as a medicine from ancient times for cure of various diseases such as toothache and problems related to teeth, asthma, gum bleeding, fever, dyspepsia, and as tonics. In Nepal's local medical system, the decoction, seeds, and fruits of Z. armatum DC. are used to play a therapeutic role. In Ayurvedic tradition, the fruits are chewed as a mouth freshener, twigs are used as a toothbrush, and a decoction serves as a gargle for stomatitis. Topical application as a paste has been noted for pain, skin diseases, and numbness of the limbs. In parts of India, the plant (known as tejphal or tirphal) appears in preparations for coughs, respiratory complaints, and intestinal parasites.

A nor-neolignan, ailanthoidol, was isolated from the wood of Z. ailanthoides, a tree used in folk medicine in Taiwan for the treatment of snake bite and the common cold.

African Traditional Medicine

In traditional medicine, many of the plant species are used in treating sickle cell anemia, trypanosomiasis, malaria, and microbial infections, including tuberculosis and enteritis, with Z. zanthoxyloides Lam. being the most reported species for these applications.

In South Africa and Kenya, pastes made from Z. species are used to suppress pain associated with wounds and to aid wound healing, while in Nigeria, Z. species like Z. zanthoxyloides are used for treating rheumatism, sickle cell anemia, toothache, urinary tract infection, and venereal diseases. Similarly, Z. zanthoxyloides root-bark is used in Uganda for healing elephantiasis, toothache, erectile dysfunction, gonorrhea, malaria, dysmenorrhea, and abdominal pain. Stem decoction of Z. zanthoxyloides is used in Côte d'Ivoire to relieve tooth pain and to treat infections caused by oral pathogens. In Togo, Z. zanthoxyloides leaves are used to treat wounds, root-bark for toothache, swellings, and worms, and to induce lactation post-partum, while the bark is used for relieving pain.

North American Traditional Use

In North American herbalism, Zanthoxylum americanum (northern prickly ash) and Z. clava-herculis (southern prickly ash) have been historically used by both Native American peoples and 19th-century Eclectic physicians. The bark and berries were applied topically or chewed to numb oral tissues for toothache, treat sore throats, and address cold-induced ailments. Eclectic physicians adopted Zanthoxylum as a remedy for chronic rheumatism, digestive sluggishness, and circulatory deficiency. These North American species were sometimes listed in older American pharmacopeias under the designation "prickly ash bark" or "prickly ash berries."

3. Key Constituents and Active Compounds

To date, over 140 compounds have been isolated and identified from Z. bungeanum alone, including alkaloids, terpenoids, flavonoids, and free fatty acids. Across the whole genus, over 500 compounds have been isolated from Z. species, and the biological activities of both the plant extracts and their phytoconstituents, including their mechanisms of action, are discussed in the literature.

Several classes of phytochemicals have been detected in Zanthoxylum species, such as terpenes, flavonoids, coumarins, phenolic acids, and alkaloids — the most reported among all the classes.

Alkaloids

Alkaloids are the top isolated compounds in the genus Zanthoxylum and numerous species have been shown to contain these types of compound. Biologically, these compounds have been reported as anaesthetics, anti-inflammatory, antibacterial, anticancer, antiviral, antidiabetic, antimalarial, and cardioprotective agents. The main types of alkaloids isolated from this genus are isoquinolines (tetrahydroisoquinolines, benzophenanthrides, oxoaporphines, indoles, carbazoles, and indolopyridoquinazolines), quinolines (furoquinolines, quinolones, and pyraquinolines), and acridones.

Among the most pharmacologically studied alkaloids are:

• Hydroxy-α-sanshool (HAS) and related sanshools: Alkylamide-class compounds responsible for the characteristic "numbing" oral sensation. Sanshools are major active ingredients of Zanthoxylum piperitum and are used as food additives in East Asia. HAS is the main active compound responsible for the special taste and diverse pharmacological activity of Z. bungeanum.
• Chelerythrine: A benzophenanthridine alkaloid. Chelerythrine is a type III benzophenanthridine alkaloid isolated from plants of the family Rutaceae (e.g., Zanthoxylum asiaticum). This bioactive compound possesses anti-inflammatory, antibacterial, antifungal, and antitumor activities.
• Berberine: An isoquinoline alkaloid found in multiple Zanthoxylum species, with well-characterized antimicrobial and metabolic activities. Chelerythrine, berberine, and canthin-6-one are antibacterial components of Zanthoxylum spp.
• Nitidine: A benzophenanthridine alkaloid with documented anticancer and antiparasitic activity.
• Fagaronine, skimmianine, kokusaginin: Furoquinoline and other alkaloids present in root bark and stem bark of multiple species. The active components of Zanthoxylum bungeanum include kokusaginin, skimmianin, diosmetin, beta-sitosterol, and quercetin.

Amides (Alkylamides)

Approximately 26 species of Zanthoxylum have been identified as containing amides, with Z. bungeanum being the species richest in amides. Amide compounds are distributed in various parts of the plant, including the roots, stems, leaves, peels, fruits, seeds, and other components. It has been established that amides are characteristic constituents within the genus. Aliphatic amides comprise the majority of these compounds (about 66.7% of the total). The amide compounds found in Zanthoxylum L. plants are also referred to as "Zanthoxylum numb-taste."

Volatile Oils and Terpenes

The plants of this genus are rich in volatile oils, alkaloids, amides, lignans, coumarins, and organic acids. The essential oils of multiple species contain monoterpenes (such as limonene, linalool, and terpinen-4-ol), sesquiterpenes, and phenylpropanoids that contribute to aroma and biological activity.

Coumarins

In the subfamily Rutoideae, the genus Zanthoxylum is characterized by the presence of different types of coumarins (simple, linear, dihydrofurocoumarins, furocoumarins, and pyranocoumarins). The angular dihydrofurocoumarins are not common in other species of the family Rutaceae, making them of chemotaxonomic value for the genus.

Flavonoids and Phenolic Acids

In Z. zanthoxyloides, neohesperidin, hesperidin, and quercetin were found to be higher in the root and trunk extracts, while hyperoside, quercetin-3-O-glucopyranoside, datiscin, and quercitrin were found to be higher in the leaf extract.

Lignans

Diarylbutirolactonic lignans such as (−)-cubebin, with trypanocidal activity, have been isolated from Z. monophyllum and Z. naranjillo.

4. Mechanisms of Action

Sensory and Neurological Mechanisms (Sanshools)

Researchers expressed 17 TRP channels in human embryonic kidney (HEK) cells and investigated their activation by hydroxy-α-sanshool (HαSS) or hydroxy-β-sanshool (HβSS) isolated from Zanthoxylum piperitum. It was found that HαSS, but not HβSS, depolarized sensory neurons with concomitant firing of action potentials and evoked inward currents. Among 17 TRP channels expressed in HEK cells, HαSS caused Ca²⁺ influx in cells transfected with TRPV1 or TRPA1, and evoked robust inward currents in cells transfected with TRPV1 or TRPA1.

However, the relative contribution of TRP channel activation versus potassium channel blockade remains a subject of scientific debate. Some studies showed the chemesthetic sensations of sanshool, instead of being mediated by activating TRPA1 or TRPV1, are caused by the activation of KCNK channels by blocking outward K⁺ current. This study further narrowed the activation effect of sanshool on KCNK channels down to three subtypes, including KCNK3 (TASK-1), KCNK9 (TASK-3), and KCNK18 (TRESK). In vitro, HAS has been shown to activate TRPV1 and TRPA1 in sensory neurons by influx of Ca²⁺ in cells. Subsequently, Bautista et al. (2008) reported the activation of somatosensory neurons including small- and large-diameter cells elicited through the unique ability of HAS to inhibit two-pore potassium channels.

Anti-inflammatory Mechanisms

In a rat model of type 2 diabetes mellitus, Zanthoxylum alkylamides (ZA), a mixed extract containing hydroxyl-γ-sanshool, hydroxyl-β-sanshool, and hydroxyl-α-sanshool, demonstrated the ability to control inflammation and address protein metabolism disorders, consequently ameliorating T2DM. The PI3K/Akt/forkhead box O signaling pathway and the TNFα/NF-κB pathway are implicated in this process. In macrophage studies, extracts from multiple Zanthoxylum species have been shown to inhibit NF-κB and MAPK signal pathways and to suppress COX-2 and iNOS expression.

Antidiabetic Mechanisms

Hydroxy-alpha-sanshool (HAS) has attracted attention because of its various biological activities, such as hypoglycemic, hypolipidemic, and antioxidant activities. In a study investigating the effects of HAS on insulin resistance, HAS reduced fasting blood glucose, promoted insulin secretion, significantly decreased levels of interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-α and monocyte chemoattractant protein-1 (MCP-1), and increased the IL-2 level in serum of insulin-resistance model mice. The active components of Zanthoxylum bungeanum — including kokusaginin, skimmianin, diosmetin, beta-sitosterol, and quercetin — may exert their therapeutic effect on diabetes mellitus by downregulating core target genes including AKT1, IL6, HSP90AA1, FOS, and JUN.

Anticancer Mechanisms

Z. bungeanum and the traditional Chinese medicine compound containing Z. bungeanum can promote apoptosis, arrest the cell cycle, inhibit cell invasion and metastasis, promote autophagy, and increase the sensitivity of chemotherapeutic drugs through P53, PI3K/AKT, Wnt/β-catenin, and other signaling pathways, which are effective against various cancers, including hepatocellular cancer, gastric cancer, and breast cancer.

Antimicrobial Mechanisms

Kinetic measurements of the bacteriolytic activities of chelerythrine against the bacteria Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) were determined by optical density based on real time assay, suggesting that its mechanism of action is not bacteriolytic. The precise antibacterial mechanism of chelerythrine is believed to involve DNA intercalation and disruption of bacterial cell membrane integrity rather than cell lysis.

5. Scientific Evidence by Area of Use

5.1 Pain and Analgesia

The analgesic effects of Zanthoxylum are among the most investigated activities across the genus. In Traditional Chinese Medicine, Zanthoxylum species are valued for their analgesic and anti-inflammatory effects, relieving pain and controlling inflammation.

Preclinical (animal) evidence: In a study of Zanthoxylum armatum, both the extract and total alkaloids from fruit and leaves significantly (p < 0.001) reduced the rectal temperature in mice. The effects of bark and root extracts were less significant. In writhing and tail flick methods, both the extract and total alkaloids from fruit showed significant (p < 0.05 and p < 0.001) antinociceptive activity. The fruit extract and crude alkaloids showed significant (p < 0.01) lowering of inflammation of paw edema in mice. Crude alkaloids from fruit and leaves showed significant enzyme inhibition with lower IC₅₀ values of 15 and 69 μg/ml against COX and 21 and 62 μg/ml against LOX.

Mechanistic (in vitro) evidence: The sanshool-TRPV1/TRPA1/KCNK channel axis has been characterized in cell culture systems (see Mechanisms section). Only 13 of the 33 traditionally used species were shown to be effective in analgesic responses in reviewed preclinical studies, and only two were employed in treating inflammation, indicating that not all traditional claims are uniformly supported.

Clinical evidence: Controlled human clinical trials specifically evaluating the analgesic effects of Zanthoxylum extracts as an isolated intervention are lacking. The evidence base remains primarily preclinical as of the latest published reviews.

5.2 Anti-inflammatory Activity

Preclinical evidence: Polyphenols of Z. bungeanum have exhibited considerable promise, as evidenced by preclinical studies in animal models, suggesting their therapeutic potential in human inflammatory diseases such as ulcerative colitis, arthritis, asthma, chronic obstructive pulmonary disease, cardiovascular disease, and neurodegenerative conditions.

The essential oil of Zanthoxylum coreanum inhibited both the IgE-antigen complex or PMA/A23187-induced β-hexosaminidase release and IL-4 production dose-dependently in RBL-2H3 mast cells, and it showed significant inhibition of LPS-induced overproduction of TNF-α, IL-6, and NO. Consistently, the protein levels of iNOS and COX-2 were also remarkably decreased by the treatment.

The hexane and 95% ethanolic extract from pericarp and seed essential oil of Z. rhetsa were the most active extracts. The pericarp hexane and ethanol extracts gave the highest inhibition of NO production with IC₅₀ values of 11.99 ± 1.66 μg/ml and 15.33 ± 1.05 μg/ml respectively, and they also showed the highest anti-inflammatory effect on TNF-α with IC₅₀ values of 36.08 ± 0.55 μg/ml and 34.90 ± 2.58 μg/ml, respectively.

Clinical evidence: Currently, several clinical trials have utilized Z. bungeanum polyphenols; however, their application in inflammatory conditions remains limited. These completed clinical studies are summarized in the literature. Notably, no severe adverse reactions associated with these polyphenols have been reported across these clinical investigations, providing a certain degree of evidence supporting their safety profile. The overall clinical evidence base is preliminary, and further controlled trials are needed to confirm efficacy in inflammatory diseases.

5.3 Antimicrobial Activity

Most of the active compounds in Zanthoxylum are alkaloids and some possess antimicrobial activity against both drug-sensitive and drug-resistant species of public health importance. Alkaloids (6-acetonyldihydronitidine, 6-acetonyldihydroavicine, and 6-acetonyldihydrochelerythrine) from the stem bark of Z. rhoifolium strongly inhibited the growth of S. aureus, S. epidermidis, K. pneumoniae, and E. coli with MIC values in the range of 1.06–12.5 μg/ml.

The minimal inhibitory concentrations of chelerythrine of 1.50 μg/mL for all bacteria tested, and between 3.12 and 6.25 μg/mL for the yeast tested, show this compound to be a more powerful antimicrobial agent when compared with the other active alkaloids isolated from Z. rhoifolium.

Chelerythrine presented bactericidal activity against Staphylococcus aureus and Streptococcus pyogenes (MBC = 3.12 and 6.25 μg/mL, respectively), and fungicidal activity against all fungi tested (MFC between 3.12–6.25 μg/mL). The alkaloid avicine also demonstrated bactericidal activity against Bacillus subtilis and Klebsiella pneumoniae (MBC = 6.25 and 12.5 μg/mL, respectively), and fungicidal activity against the fungi tested.

The methanoid extract of the root powder of Z. zanthoxyloides contains flavonoids, chelerythrine, berberine, and phenol canthine-6-one, which have revealed antimicrobial activity. All evidence in this area is currently from in vitro studies; no human clinical trials have evaluated Zanthoxylum preparations specifically for infectious disease treatment.

5.4 Antimalarial and Antiparasitic Activity

Four alkaloids — bis-dihydrochelerythrinyl ether, skimmianine, buesgenine, and chelerythrine — isolated from roots, root-bark, and stem-bark of Z. zanthoxyloides exhibited anti-plasmodial activity against chloroquine-sensitive (3D7) strains of P. falciparum with IC₅₀ values of 4.3, 0.7, 2.0, and 0.4 μg/ml, respectively. Nitidine from Z. gilletii stem bark exhibited anti-plasmodial activity against P. falciparum strain FcB1 with IC₅₀ < 5 μg/ml by halting DNA synthesis in the parasite. This evidence is entirely preclinical (in vitro and animal models); human trials are absent.

5.5 Anti-sickling Activity (Sickle Cell Disease)

Some members of genus Zanthoxylum (e.g., Z. zanthoxyloides, Z. leprieuri, and Z. gilletii) are among the plants with a history of traditional use in managing sickle cell disease (SSD). Among the species, Z. zanthoxyloides, Z. lemairei, Z. leprieurii, Z. tessmannii, and Z. gilletii have been investigated for anti-sickling activity in vitro. The specific compounds responsible for anti-sickling activity of the plant extracts were scarcely reported. Three divallinoylquinic acids (burkinabins A, B, and C) isolated from Z. zanthoxyloides root bark at 1.964 mg/ml inhibited sickling of deoxygenated erythrocytes by 77%, 78.6%, and 82.5%, respectively. Evidence is in vitro only; controlled human trials are absent.

5.6 Antidiabetic and Metabolic Activity

The biological activities in relation to neuronal and metabolic health, such as antioxidant, analgesic, chemoprotective, antidiabetic, antiulcer, anti-Alzheimer's disease, anti-inflammatory, and anti-hypertensive activities, have been reported for Zanthoxylum species.

In an in vivo antidiabetic study of Z. armatum aqueous leaf extract, blood glucose level was monitored at different intervals after administration of varying doses for hypoglycemic (100–6000 mg/kg b.w.) and antihyperglycemic (250 mg/kg b.w.) effect in normoglycemic and diabetic mice. In vitro enzymatic inhibition activity was also tested against α-amylase, α- and β-glucosidase, and lipase. These findings are from preclinical models only.

Network pharmacology analyses have identified potential anti-diabetic targets. The therapeutic effect of Zanthoxylum bungeanum on diabetes mellitus may be achieved by downregulating core target genes including AKT1, IL6, HSP90AA1, FOS, and JUN. However, this computational evidence requires experimental and clinical validation.

5.7 Anti-obesity and Lipid Metabolism

HAS showed good anti-obesity effects both in vivo and in vitro. HAS, an amide derived from the fruit of Zanthoxylum bungeanum, promotes the management of obesity. One of the important underlying mechanisms involves the activation of the cell membrane receptor TRPV1 cation channel and the promotion of white adipose tissue (WAT) browning. Although HAS showed good anti-obesity effects, the special structure of HAS makes it insoluble in water and prone to configuration transformation and oxidative degradation, which seriously limits its drug development. All evidence is preclinical; no human trials on weight management using Zanthoxylum extracts were identified.

5.8 Anticancer Activity

Z. bungeanum and its extracts have demonstrated promising effects against various tumors, indicating their potential use in future cancer therapies. However, clinical studies evaluating the antitumor efficacy and toxicity of Z. bungeanum in humans are scarce. Therefore, well-designed clinical trials should be prioritized in the future to establish a solid foundation for its use in cancer treatment.

The multiple target mechanisms of anticancer activities identified in vitro for some Z. species-derived compounds make them strong candidates for in vivo studies and human clinical trials, and further development as anticancer agents. As of the latest comprehensive reviews, anticancer evidence remains confined to in vitro and some animal studies.

5.9 Gastrointestinal Activity

Extracts and compounds of Z. bungeanum have been shown to possess regulatory effects on the gastrointestinal system and nervous system, among other effects. Network analysis identified 59 compounds in Zanthoxylum pericarp that target 38 genes related to inflammatory bowel disease (IBD), including PTGS2, PPARG, and GPBAR1. In a mice model of DSS-induced colitis, Zanthoxylum pericarp significantly reduced colonic epithelial damage and oxidative stress markers such as iNOS and nitrotyrosine. These findings suggest that Zanthoxylum pericarp has protective effects against DSS-induced colonic damage owing to its anti-inflammatory and antioxidant properties, making it a potential candidate for IBD treatment. Evidence remains preclinical.

5.10 Antioxidant Activity

The biological activities in relation to neuronal and metabolic health — including antioxidant, analgesic, chemoprotective, antidiabetic, antiulcer, anti-Alzheimer's disease, anti-inflammatory, and anti-hypertensive activities — are well-characterized in the literature. The involvement of oxidative stress in the development and progression of many diseases has been well-characterized. The pathogenesis of neurodegenerative and cardiovascular diseases, many cancers, and malaria involve oxidative stress. Antioxidant activity has been consistently demonstrated across multiple Zanthoxylum species in in vitro assays (DPPH, ABTS, FRAP), though clinical antioxidant efficacy studies are not available.

6. Body Systems and Health Areas

• Nervous system: Sensory neuron modulation via TRP and KCNK ion channels; analgesic and numbing effects via sanshools; potential anti-neurodegeneration activity (under investigation).
• Gastrointestinal system: Traditionally used for abdominal pain, bloating, vomiting, diarrhea, intestinal parasites, and digestive disorders; preclinical evidence for colitis protection.
• Immune system: Anti-inflammatory activity via NF-κB, MAPK, COX/LOX inhibition; preclinical evidence for allergic inflammation modulation.
• Metabolic/endocrine system: Preclinical evidence for antidiabetic, hypolipidemic, and anti-obesity activity.
• Cardiovascular system: Preclinical evidence for antihypertensive and cardioprotective activities.
• Infectious diseases: Preclinical antimicrobial, antifungal, antimalarial, anti-trypanosomal, and antiviral activity documented in vitro.
• Oral health: Traditional and preclinical evidence for toothache relief and oral antimicrobial effects.
• Blood disorders: Preclinical anti-sickling evidence for certain African species.
• Oncology: Preclinical anticancer data for multiple cell lines; no clinical evidence.
• Skin: Traditional use for eczema, dermatosis, wounds; preclinical anti-allergic skin inflammation evidence.

7. Dosage Forms and Reported Dosages

Note: The following dosages are drawn from traditional references and preclinical study designs. No approved therapeutic dosages for human supplemental use have been established in evidence-based guidelines as of the available literature.

• Traditional decoction (TCM): 3–6 grams of dried fruit pericarp, as cited in traditional reference sources and practitioner literature.
• Traditional powder (TCM): 500 mg–2 grams per dose.
• Preclinical in vivo (antidiabetic, Z. armatum): Blood glucose assessments used varying doses of the aqueous leaf extract for hypoglycemic effect (100–6000 mg/kg b.w.) and antihyperglycemic effect (250 mg/kg b.w.) in mice. These are animal study doses; human equivalents are not established.
• Preclinical in vivo (LD₅₀, Z. bungeanum): Early work determined the lethal dose of water extract of Z. bungeanum in mice was about 45 g/kg following intragastric administration, calculated on the basis of crude herb mass.
• Antimicrobial (in vitro): Chelerythrine from Z. rhoifolium showed a minimum inhibitory concentration of 1.50 μg/mL for all bacteria tested; MFC against fungi of 3.12–6.25 μg/mL.
• Essential oil forms: Used in topical preparations and as flavor ingredients; dose standardization for medicinal use is not established in peer-reviewed clinical literature.

There are not enough studies regarding the pharmacokinetics and clinical research of Z. bungeanum, and few evaluations of the toxicity on a cellular and molecular level have been explored. Future study of Z. bungeanum should focus more on the pharmacokinetics of compounds besides alkylamides, and toxicity studies should be performed at the molecular and cellular level to investigate any side effects in clinical research.

8. Safety Considerations and Interactions

General Toxicological Profile

For centuries, Zanthoxylum bungeanum has been regarded as a traditional Chinese medicinal herb with minimal toxicity. However, modern research on its toxicological properties remains limited, with most studies focusing on the evaluation of its extract. Early work determined the lethal dose of water extract of Z. bungeanum in mice was about 45 g/kg following intragastric administration. A subsequent investigation in 2010 reported a slightly higher LD₅₀ of 51.14 g/kg, with the authors suggesting that variations in plant genetics, growing conditions, and post-harvest processing could explain the differences; the extract produced only minor hepatic alterations — such as slight ballooning degeneration, cytoplasmic vacuolization, and occasional necrotic foci — indicating minimal liver toxicity at high doses in mice.

Predicted Hepatotoxicity Risk

Hepatotoxicity remains a major reason for drug withdrawal from pharmaceutical development and clinical uses. Out of the compounds found in the genus Zanthoxylum, approximately 23.6% were identified as hepatotoxic based on the binary yes/no assessment conducted using pkCSM computational modeling. This is a theoretical, in silico assessment and should not be interpreted as confirmed clinical hepatotoxicity; it underscores the need for careful monitoring in any clinical development of isolated compounds.

Sanshool Sensory Effects

Sanshools cause irritant, tingling, and sometimes paresthetic sensations on the tongue. These effects are dose-dependent and are the basis of the characteristic numbing sensation of Sichuan pepper in food applications. At culinary doses these effects are transient; the safety profile at pharmacological doses in sustained supplementation is not well characterized in clinical literature.

HAS Physicochemical Limitations

The special structure of HAS makes it insoluble in water and prone to configuration transformation and oxidative degradation, which seriously limits its drug development. This is relevant to product formulation and bioavailability of HAS-containing supplements.

Clinical Trial Safety Data

Several clinical trials have utilized Z. bungeanum polyphenols; however, their application in inflammatory conditions remains limited. Notably, no severe adverse reactions associated with these polyphenols have been reported across these clinical investigations, providing a certain degree of evidence supporting their safety profile. These findings are preliminary and the scope of clinical trials conducted to date is narrow.

Furocoumarins and Photosensitivity

Multiple Zanthoxylum species contain furocoumarins — a class of phototoxic compounds also found in other Rutaceae. While this concern has been documented pharmacologically for the plant family, specific clinical photosensitivity data for Zanthoxylum supplements in human populations have not been established in the peer-reviewed sources reviewed here.

Lack of Established Drug Interaction Data

Berberine, one of the principal alkaloids in Zanthoxylum, is known in broader botanical literature to inhibit cytochrome P450 enzymes (particularly CYP3A4 and CYP2D6) when studied as an isolated compound, with potential to affect the metabolism of co-administered pharmaceuticals. However, specific drug interaction data for whole-plant Zanthoxylum preparations have not been formally investigated in human pharmacokinetic studies based on the sources available here.

Pregnancy and Pediatric Use

Evidence-based safety data for use during pregnancy, lactation, or in pediatric populations are not available in the reviewed literature. Traditional Chinese medicine sources generally caution against use during pregnancy; however, this traditional caution is not supported by clinical trial data.

9. Evidence Strength Summary

• Strong (mechanistic/in vitro): Characterization of sanshool interactions with TRPV1, TRPA1, and KCNK channels; antimicrobial activity of chelerythrine, berberine, and other alkaloids in cell-free and cell-based assays.
• Moderate (animal models): Analgesic, anti-inflammatory, antidiabetic, antioxidant, and anti-sickling activities demonstrated in rodent and other animal models across multiple species.
• Weak/preliminary (human): A limited number of clinical studies on Z. bungeanum polyphenols have been completed, without reporting severe adverse events, but formal efficacy endpoints in human inflammatory disease trials are not yet well-established. No approved therapeutic indications exist in major Western regulatory frameworks.
• Absent: Controlled human clinical trials on analgesic, antimicrobial, anticancer, anti-sickling, or anti-obesity applications. Formal pharmacokinetic studies in humans across most compounds and species.

References

• Pharmacological activities of Zanthoxylum L. plants and its exploitation and utilization — PMC / Heliyon (2024)
• Zanthoxylum Species: A Review of Traditional Uses, Phytochemistry and Pharmacology in Relation to Cancer, Infectious Diseases and Sickle Cell Anemia — Frontiers in Pharmacology / PMC (2021)
• Zanthoxylum Species: A Comprehensive Review of Traditional Uses, Phytochemistry, Pharmacological and Nutraceutical Applications — Molecules / PMC (2021)
• Ethnobotanical uses, phytochemistry and pharmacology of pantropical genus Zanthoxylum L. (Rutaceae): An update — Journal of Ethnopharmacology / ScienceDirect (2022)
• Zanthoxylum bungeanum Maxim. (Rutaceae): A Systematic Review of Its Traditional Uses, Botany, Phytochemistry, Pharmacology, Pharmacokinetics, and Toxicology — PMC (2017)
• Research advances of Zanthoxylum bungeanum Maxim. polyphenols in inflammatory diseases — Frontiers in Immunology / PMC (2024)
• Hydroxy-alpha-sanshool activates TRPV1 and TRPA1 in sensory neurons — European Journal of Neuroscience / PubMed (2007)
• Integrated metabolomics and transcriptomics reveal the potential of hydroxy-alpha-sanshool in alleviating insulin resistance — PMC (2025)
• Anti-Inflammatory Investigations of Extracts of Zanthoxylum rhetsa — PMC (2021)
• Phytochemical investigation, anti-inflammatory, antipyretic and antinociceptive activities of Zanthoxylum armatum DC extracts — PubMed (2020)
• A mechanistic review on Zanthoxylum species for anti-inflammatory and analgesic potentials — ScienceDirect (2024)
• Structure-Activity Relationship of Benzophenanthridine Alkaloids from Zanthoxylum rhoifolium Having Antimicrobial Activity — PMC (2014)
• Anti-allergic Inflammatory Effects of the Essential Oil From Fruits of Zanthoxylum coreanum Nakai — PMC (2018)
• Therapeutic Potential of the Genus Zanthoxylum Phytochemicals: A Theoretical ADME/Tox Analysis — PMC (2023)
• Investigation on the Mechanisms of Zanthoxylum bungeanum for Treating Diabetes Mellitus Based on Network Pharmacology, Molecular Docking, and Experiment Verification — PMC (2023)
• Evaluation of the antidiabetic property of aqueous leaves extract of Zanthoxylum armatum DC. — PMC (2018)
• Antitumor components and mechanisms of Zanthoxylum bungeanum Maxim with medicine and food homology — PMC (2025)
• Chemical composition, sensory properties and application of Sichuan pepper (Zanthoxylum genus) — ScienceDirect (2019)
• Antibacterial and antifungal activities of extracts of Zanthoxylum chalybeum and Warburgia ugandensis — PMC (2008)
• Cytotoxicity and enhancement activity of essential oil from Zanthoxylum bungeanum Maxim. as a natural transdermal penetration enhancer — PMC (2014)
• Assessing antioxidant, antidiabetic potential and GCMS profiling of ethanolic root bark extract of Zanthoxylum rhetsa — PMC (2024)