Daphne

Daphne: A Comprehensive Reference on the Genus, Its Medicinal Constituents, and Pharmacological Evidence

1. Identity and Botanical Classification

Genus and family: Daphne L. is a genus of flowering shrubs belonging to the family Thymelaeaceae. The genus was first described by Carl Linnaeus in 1753 in Species Plantarum, originally recognizing 10 species. With approximately 95 species, Daphne is the most diverse genus in the Thymelaeaceae family. The genus contains over 90 species distributed in Asia, Europe, and parts of North Africa.

Taxonomic note: According to Halda (1998), the genus Daphne is divided into 15 subgenera and 10 sections. Daphne laureola L. was chosen as the lectotype of the genus.

Medically and pharmacologically significant species include:

• Daphne giraldii Nitsche — the principal source of the TCM drug "Zushima" (Cortex Daphnes), widely used for musculoskeletal conditions.
• Daphne genkwa Sieb. et Zucc. — an important traditional Chinese medicine (TCM) known in Chinese as "Yuan Hua"; the dried flower buds are the official part used.
• Daphne mezereum L. — known as mezereon or February Daphne; native to Europe and western Asia and historically used in Scandinavian and European folk medicine.
• Daphne mucronata Royle — used in South Asian traditional medicine.
• Daphne oleoides Schreb. — found in the Eastern Mediterranean and Middle East, used in Unani and regional folk medicine.
• Daphne acutiloba Rehd. — used in Chinese traditional medicine under the name "Jin yao dai."

Natural source and habit: Daphne giraldii is mainly distributed in the cold-tolerant and alkali-resistant northwest region of mainland China, where it grows as alpine shrubs or in hillside forests and can reach a height of 45–70 cm. Daphne acutiloba grows in southwest China at altitudes up to 2,800 m, especially in Hubei, Sichuan, and Yunnan provinces. Daphne mezereum is native to Europe and western Asia and is a member of the family Thymelaeaceae.

Common forms and preparations: Cortex Daphnes (Zushima) is the processed stem and root barks of Daphne giraldii Nitsche, Daphne tangutica Maxim., and Daphne retusa Hemsl., as designated in the Pharmacopoeia of the People's Republic of China (1977); the main processing methods include rinsing, drying, and cutting pharmaceutical materials. Preparations encountered in the scientific literature include decoctions of bark, ethanol and water-ethanol extracts, topical patches (plasters), and tablets. Zushima-Pian (ZP), a traditional Chinese medicine tablet, was officially recorded by the Ministry of Public Health of China for the treatment of arthritis and rheumatic arthritis.

2. Traditional and Historical Uses

2.1 Traditional Chinese Medicine

The species of the genus Daphne are used in the traditional medicine of China, Tibet, Korea, and the Middle East for the treatment of various conditions.

Zushima, the dried stem bark and root bark of Daphne giraldii Nitsche, is a traditional Chinese medicine used for over two thousand years in China for inflammation-related symptoms, including joint pain, and is mainly used to treat rheumatoid arthritis (RA) in clinics. Human interest in D. giraldii dates back to the ancient Song dynasty, when it was exploited as a folk medicine in northwest China for the treatment of bruises, rheumatism, aches, and arthralgia. It is used to treat a broad range of ailments including bruises, arthralgia, quadriplegia, traumatic pain, toothache, abdominal pain, waist ache, lumbago, bronchitis, and rheumatoid arthritis.

The flower bud of D. genkwa, a Chinese traditional medicine, has been used as a diuretic, antitussive, and pesticide, and one of its synonyms is "yu-du," meaning "a fish poison." Genkwa flos was first recorded in the Sheng Nong's Herbal Classic, listed as a low-grade medicine, and was mainly for the treatment of cough, asthma, swollen pharynx, shortness of breath, and carbuncle swelling. More than 250 compounds have been isolated and identified from D. genkwa, including flavonoids, diterpenoids, coumarins, and lignans; diterpenoids and flavonoids, as the main bioactive ingredients, have been shown to have anti-inflammatory, anti-tumor, diuretic, and anti-fertility effects.

The root and bark of D. acutiloba are used in Chinese traditional medicine under the name "Jin yao dai" to treat bruises and scrofula, and diterpenes and phenols extracted from the plant show anti-HIV-1 activity.

2.2 Scandinavian and European Folk Medicine

Daphne mezereum L. was an important medicinal plant in Norway during the 18th and 19th centuries and used against diseases such as diarrhea, swelling, stomach pain, and tuberculosis. This plant has been used to make dyes, treat rheumatism and indolent ulcers, and as a cosmetic. In homeopathy, the plant is used to treat primarily skin disorders but is also prescribed to treat anxiety related to digestive disorders and congestion; however, once the toxicity of the plant was more fully understood, these uses were largely abandoned.

2.3 Other Regional Traditions

Several Daphne plants have been used as traditional medicines for the treatment of cancer, inflammation, and rheumatism in Asia, North Africa, and Europe, and some of these plants were also regarded as virulent poisons.

The extract of D. mucronata has traditionally been used for the treatment of infections related to skin, allergies, and cancer; leaves and root extracts have also been used in traditional Chinese medicine to treat toothache, ulcers, rheumatism, and as a purgative.

According to Chinese medicine theory, the function of Cortex Daphnes herb is to remove blood stasis and relieve pain, removing cold-wind and dredging collaterals; it is used to treat headache, stomach ache, bruises, limb numbness, and joint pain.

3. Key Phytochemical Constituents

Daphne plants are the source of valuable bioactive phytochemicals such as coumarins, flavonoids, lignans, steroids, and different classes of terpenes. The main chemical classes are described below.

3.1 Diterpenoids (Daphnanoids)

There are abundant natural diterpenoids in the plants of the genus Daphne, featuring a 5/7/6-tricyclic ring system and usually with an orthoester group; so far, a total of 135 diterpenoids have been isolated from species of the genus, which can be classified into three main types according to the substitution pattern of ring A and oxygen-containing functions at ring B.

Diterpenoids are believed to be representative components of the genus Daphne; the archetype of one class, daphnetoxin, was first isolated from D. mezereum and named after the genus, and daphnetoxin and its analogues are collectively known as the daphnetoxin class. Genkwanine A from D. genkwa is the archetypical diterpenoid of the genkwanines class.

The principal diterpenoid toxins are mezerein and daphnetoxin. Mezerein is a toxic diterpene ester found in the sap of Daphne mezereum and related plants; plants of the genera Euphorbiaceae and Thymelaeaceae possess a variety of phorbol esters that share the capacity of mimicking diacylglycerol (DAG) and thus activating different isoforms of protein kinase C. Mezerein was first isolated in 1975.

Key bioactive diterpenoids include genkwadaphnin, yuanhuacin, yuanhuadin, and simplexin. Genkwadaphnin is a daphnane diterpene ester molecule mainly isolated from Daphne genkwa, Dendrostellera lessertii, Daphne odorata, and related species; it has been reported to exert therapeutic potential against hepatocellular carcinoma, human colon cancer, squamous cell carcinoma, and leukemia, and has a significant role in innate immunity, melanogenesis, skeletal diseases, and inflammatory cytokines.

3.2 Coumarins

The coumarin class is a defining feature of the genus. Key compounds include:

• Daphnetin (7,8-dihydroxycoumarin, DAP): Daphnetin is generally an odorless and tasteless white or off-white powder that is freely soluble in ethanol, methanol, and dimethylsulfoxide while slightly soluble in water. As an increasingly well-known derivative of coumarin, daphnetin (7,8-dihydroxycoumarin) has demonstrated various pharmacological activities, including anti-inflammation, anti-cancer, anti-autoimmune diseases, antibacterial, organ protection, and neuroprotection properties.
• Daphnin: Daphnin is a hydroxycoumarin compound; coumarins are a family of benzopyrones widely distributed in nature; daphnetin is a dihydroxycoumarin and can undergo enzymatic glycosylation to yield 7-O-glucoside, also called daphnin.
• Daphnoretin: Daphnoretin, a primary active ingredient of Daphne giraldii Nitsche, exhibits various pharmacological effects, including antitumor, antioxidative, and anti-inflammatory properties.
• Dimeric and trimeric coumarins: Coumarins found in Daphne include daphnetin, DAP-8-glucoside, daphnin, esculin, umbelliferone, and acetyl-umbelliferone; rutarensin, daphnoretin, daphneretusin-A, and dimethyl-daphnoretin-7-O-glucoside are categorized among dimeric coumarins, while trimeric coumarin metabolites including daphneretusin B and triumbellin have also been identified in Daphne species.

The major toxic components of the genus include coumarins like daphnin — among the most common — and daphnane diterpenes like mezerein and daphnetoxin.

3.3 Flavonoids

Phytochemical investigation on D. giraldii has revealed that it is rich in different types of secondary metabolites including flavonoids, coumarins, lignans, and diterpenes. Chromatographic fractionation of the EtOH extracts of Zushima has led to the isolation of 26 flavonoids, including ten flavonols, one flavone, two dihydroflavones, a dihydroflavonol, six flavans, three chalcones, and three 1,3-diarylpropanes.

Key flavonoids include genkwanin (a non-glycosylated flavone) and the biflavonoids genkwanol A and related compounds. Genkwanin is a non-glycosylated flavone found in several medicinal plants including Genkwa Flos; in vitro and in vivo biological and pharmacological investigations showed that genkwanin exhibits remarkable antioxidant and anti-inflammatory activities, and, via activation of glucokinase, has shown antihyperglycemic activity with a potential role against metabolic syndrome and diabetes. Additionally, genkwanin has revealed cardioprotective and neuroprotective properties, and has shown antitumor, antibacterial, antiviral, and dermato-protective effects.

3.4 Lignans and Other Constituents

Phytochemical studies on D. giraldii have identified more than 150 compounds consisting of various classes including coumarins, flavonoids, lignans, diterpenes, and miscellaneous ingredients, of which coumarins and flavonoids are the two major classes.

Phytochemical analysis of D. mucronata showed that it contains coumarins, flavonoids, triterpenoids, diterpene, sterols, lignin cumarinolignans, glucosides, daphnecin, aquillochin, daphnine, and umbelliferone.

HPLC analysis of D. mucronata identified a total of eight phenolic compounds: malic acid, gallic acid, chlorogenic acid, epigallocatechin gallate, quercetin, morin, ellagic acid, and rutin.

4. Mechanisms of Action

4.1 Daphnetin: Protein Kinase Inhibition

As a natural product, daphnetin has been recognized as an inhibitor of protein kinase; among coumarin and its derivatives — including daphnetin, esculin, and various hydroxy-coumarins — only daphnetin was found to inhibit protein kinases potently; specifically, daphnetin was verified to inhibit tyrosine-specific protein kinase EGFR (IC₅₀ = 7.67 µM) and serine/threonine kinases PKA (IC₅₀ = 9.33 µM) and PKC (IC₅₀ = 25.01 µM) in vitro. Mechanically, the inhibition of EGF receptor tyrosine kinase by daphnetin was competitive with respect to ATP and non-competitive with respect to the peptide substrate; moreover, the hydroxylation at the C8 position is likely essential for daphnetin to function as a protein kinase inhibitor.

4.2 Anti-inflammatory Pathways

(-)-Aptosimon, isolated from flower buds of Daphne genkwa, inhibited cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and suppressed tumor necrosis factor (TNF)-alpha production; these effects were attributed to inhibition of LPS-induced nuclear factor-kappaB (NF-κB) activation by preventing degradation of inhibitor kappa B-alpha (IκB-α).

Genkwanin exerts its anti-rheumatoid arthritis effect through downregulating the activation of the NF-κB pathway and mRNA expressions of inflammatory mediators, and also by inhibiting the abnormal proliferation of fibroblast-like synoviocytes (FLSs) and their NO and IL-6 secretion levels.

Daphnane diterpenes — very common in the Daphne genus — stimulate protein kinase C, similarly to phorbol esters (tigliane diterpenes), which are rare in the genus.

4.3 Antitumor Mechanisms

Daphnan-type diterpenes from Daphne species demonstrate notable antineoplastic and cytotoxic effects against human tumor cell lines; acutilobin G, for instance, showcases considerable cytotoxic activity tested across five human cancer cell lines.

Studies have demonstrated daphnoretin's substantial antitumor activity across various cancers, including inhibition of proliferation, induction of apoptosis, and cell cycle arrest.

4.4 Hepatoprotective Mechanisms

Daphnetin has been reported to attenuate t-BHP-triggered hepatotoxicity as well as mitochondrial dysfunction in HepG2 cells, and to protect against APAP-induced acute liver failure in mice; the hepatoprotective mechanism against APAP relies on the regulation of the Nrf2 signaling pathway, with daphnetin suppressing JNK and ASK1 phosphorylation, Txnip and NLRP3 expression, and caspase-3 cleavage.

Daphnetin restored near-control levels of the hepatic enzymes ALT and AST and markedly improved liver histopathology in CCl₄-treated mice; it also reduced malondialdehyde levels in liver tissues, and mRNA analysis revealed that the expression of HO-1, dependent on the Nrf2 pathway, was induced, facilitating Nrf2 nuclear translocation to confer hepatoprotection against oxidative injury.

4.5 Neuroprotective Mechanisms

Daphnetin enhanced the expression of HSP-70, which was regulated by ERK signaling, and also protected against oxidative stress-induced neuronal injury by the suppression of p38 and phosphorylated JNK. Daphnetin accelerated the biosynthesis of adrenocorticotropic hormone (ACTH) from the pituitary gland through the neurosecretory mechanism of the hypothalamus, and significantly inhibited neuronal apoptosis by regulating the balance of Bcl-2 and Bax expression.

5. Scientific Evidence by Area of Use

5.1 Musculoskeletal Pain and Osteoarthritis — Human/Clinical Evidence

The most clinically advanced application of Daphne-derived preparations is the topical use of Cortex Daphnes (Zushima) patch for joint and musculoskeletal pain.

Randomized Controlled Trial (Knee Osteoarthritis): A multicenter, non-inferiority, randomized, parallel-group clinical trial (NCT02770950) was conducted to evaluate the efficacy of Cortex Daphnes patch compared with topical nonsteroidal anti-inflammatory drugs in patients with knee OA; Cortex Daphnes patch had been widely used for symptomatic knee OA in China, but clinical evidence supporting its use had been scant prior to this trial. A total of 264 symptomatic knee OA patients were treated with Cortex Daphnes or indomethacin cataplasms applied to affected sites once daily for 2 weeks; the primary outcome was improvement in knee pain on walking assessed using a visual analog scale (VAS), with a non-inferiority margin set at –5 mm; secondary outcomes included changes in WOMAC total score and subscores, the SF-36, and global patient assessment.

Results showed that the Cortex Daphnes patch was non-inferior to indomethacin cataplasms for the primary outcome, with a group difference (Cortex Daphnes patch–indomethacin cataplasm) of 2.1 mm (95% CI: 2.1–6.4). Cortex Daphnes (Zushima) patches were shown to provide similar effects to topical NSAIDs when used for OA of the knee.

Safety signal in this trial: Overall, 28.8% of patients in the Cortex Daphnes patch group and 9.8% in the indomethacin cataplasm group reported treatment-related adverse events, the vast majority of which were mild-to-moderate skin irritation.

Evidence assessment: This single multicenter RCT provides controlled clinical evidence for topical efficacy in knee OA, though it was a non-inferiority study compared to another topical agent rather than placebo, was of short duration (2 weeks), and was conducted exclusively in a Chinese hospital setting. No long-term RCT evidence exists for internal formulations of Daphne in Western clinical populations.

5.2 Anti-inflammatory and Analgesic Activity — Preclinical Evidence

The genus possesses a broad spectrum of biological activity including antimicrobial, antioxidant, analgesic, anti-inflammatory, cytotoxic, anti-ulcerogenic, abortive, hypocholesterolemic, and hemostatic effects. The preponderance of anti-inflammatory evidence comes from in vitro cell models and animal studies:

• COX-2 and iNOS inhibition by aptosimon (isolated from D. genkwa flower buds) has been demonstrated in LPS-stimulated macrophage cell cultures (RAW264.7), with concomitant NF-κB suppression.
• Extracts and pure compounds of D. giraldii were found to possess anti-inflammatory, anti-nociceptive, cytotoxicity, antimalarial, immunomodulating, sedative, and hypnotic effects.
• Diterpenoids genkwadaphin and 1,2-dehydrodaphnetoxin and the coumarin daphnetin from Daphne oleoides inhibited proinflammatory cytokines IL-1β, IL-1α, and TNFα at test concentrations of 1–30 µg/ml in vitro.

No large, placebo-controlled, oral human clinical trials evaluating anti-inflammatory or analgesic outcomes of purified Daphne constituents in human populations have been identified in the peer-reviewed literature.

5.3 Antitumor Activity — Preclinical Evidence

The water-alcohol extract of D. mezereum has shown antileukemic activity on P-388 lymphocytic cells in mice; the active compound mezerein, isolated from this plant, has shown a significant inhibitory effect against P-388 cells and L-1210 type leukemia in mice at the 50 µg dosage.

Daphnane diterpene esters isolated from flower buds of Daphne genkwa induce apoptosis in human myelocytic HL-60 cells and suppress tumor growth in Lewis lung carcinoma (LLC)-inoculated mouse models.

Daphnetin exhibits antitumor properties, while daphnodorin A presents anti-HIV activity.

Diterpenes and phenols extracted from D. acutiloba show anti-HIV-1 activity.

Further scientific data on human clinical trials is needed to ensure the safety and efficacy of key diterpenoid compounds, such as genkwadaphnin, in medicine. All antitumor evidence available to date is in vitro or from animal model studies; no human clinical trials for antitumor applications have been identified.

5.4 Neuroprotection — Preclinical Evidence

Daphnetin (DAP) has been reported to have multiple pharmacological actions including analgesia, antimalarial, anti-arthritic, and anti-pyretic properties. In animal studies, DAP treatment (intracerebroventricularly) reduced infarct volume at 24 hours after ischemia/reperfusion injury and improved neurological behaviors in a middle cerebral artery occlusion mouse model; DAP also had protective effects on infarct volume in neonate rats even when administered at 4 hours after cerebral hypoxia/ischemia injury.

Daphnetin protected against glutamate toxicity in hippocampal HT-22 cells in a concentration-dependent manner.

All neuroprotection evidence for daphnetin is from animal models and cell lines; no human clinical data are available.

5.5 Hepatoprotection — Preclinical Evidence

One research study suggested that daphnetin administered for 4 weeks at 4.5 mg/kg effectively protected the liver from CCl₄-induced damage in mice, possibly through its antioxidant and anti-inflammatory effects.

In a study of D. mucronata, the extract at doses of 250 and 500 mg/kg body weight given for eight days to paracetamol-intoxicated rabbits demonstrated effects compared with standard Silymarin; levels of liver enzymes (AST, ALT, ALP) and kidney biomarkers (urea, uric acid, creatinine) as well as lipid peroxidation (MDA) were assessed. This constitutes preliminary animal-only evidence; no human hepatoprotection trials have been conducted.

5.6 Metabolic (Anti-amylase / Blood Glucose) Activity — Preclinical Evidence

The inhibitory effect of daphnetin was evaluated against salivary and pancreatic α-amylases and α-glucosidase in vitro; enzyme kinetics studies revealed that the inhibition was competitive in nature, and pretreatment with daphnetin was found to inhibit the amylases in vivo as confirmed by the oral starch tolerance test (OSTT). The impact of the inhibitory effect of daphnetin in vivo was comparable to the positive control, acarbose, in all aspects. This is in vitro and animal evidence only.

5.7 Antimicrobial Activity — Preclinical Evidence

Daphne species exhibit varying antimicrobial properties; for example, D. mezereum and D. gnidium show activity against E. coli and S. aureus, and these extracts have been confirmed to contain significant levels of bioactive compounds responsible for these effects. Evidence is confined to in vitro models.

6. Body Systems and Health Areas

Based on the available scientific literature, Daphne preparations and isolated constituents have been investigated across the following body systems:

• Musculoskeletal system: Rheumatoid arthritis, osteoarthritis, musculoskeletal pain, bruises (supported by one RCT for topical use)
• Immune/Inflammatory system: Modulation of NF-κB, COX-2, iNOS, TNF-α, IL-1β, IL-6 (preclinical)
• Oncology: Cytotoxic and pro-apoptotic effects on multiple cancer cell lines and mouse tumor models (preclinical only)
• Nervous system: Neuroprotection against ischemia-reperfusion and glutamate toxicity (preclinical)
• Hepatobiliary system: Hepatoprotection against chemical-induced liver damage (preclinical)
• Renal system: Nephroprotection (limited preclinical evidence)
• Metabolic system: Antihyperglycemic activity via α-amylase and α-glucosidase inhibition (preclinical)
• Microbiology: Antimicrobial activity against gram-positive and gram-negative bacteria (in vitro)
• Cardiovascular: Influence on blood activities and cardiovascular functions (limited preclinical data)

7. Dosage Forms and Reported Dosages

No standardized international dosage recommendations exist for Daphne preparations in any regulatory jurisdiction outside China. The following dosages appear in the primary research literature cited above:

• Cortex Daphnes patch (topical, knee OA clinical trial): Applied to affected sites once daily for 2 weeks in a 264-patient RCT.
• Daphnetin (animal, hepatoprotection): 4.5 mg/kg administered for 4 weeks in mice in a CCl₄ liver damage model.
• Daphnetin (animal, hepatotoxicity study at high doses): 10, 20, and 30 mg/kg for 16 weeks was verified to ameliorate chemically induced hepatocellular changes in animal models.
• D. mucronata extract (animal, hepatoprotection): 250 and 500 mg/kg body weight given for eight days to paracetamol-intoxicated rabbits.
• Mezerein (animal, antileukemic): 50 µg dosage showed significant inhibitory effect against P-388 cells and L-1210 leukemia in mice.

8. Safety Considerations and Toxicology

8.1 General Toxicity of the Genus

Daphne is a famously toxic plant genus with every studied species reported as toxic; all parts of these plants are toxic, with the berries being particularly so, and the bright red ripe berries pose a particular danger for children and may prove fatal.

Symptoms of Daphne ingestion include burning of the throat and stomach, nausea, vomiting, gastroenteritis, internal bleeding, bloody diarrhoea, spasms, paralysis, kidney disturbance, bradycardia, circulatory arrest, and coma.

8.2 Toxic Constituents

Daphne mezereum is toxic because of the compounds daphnin, mezerein, and daphnetoxin, which are partially present in the fruits and the twigs; when interacting with these parts of the plant, gastrointestinal effects can occur which eventually can cause delirium, seizures, and death; some people experience only skin rash or eczema.

Mezerein is highly liposoluble and can cause vomiting, diarrhea, and burning of the mouth; when a large dose is taken, there can be shivering, dilation of the pupils, damage to the oral passages and the intestine, and even death.

Ingestion of plant parts leads within a few hours to severe irritation and a burning sensation in the mouth, with swelling of the lips and face, increased salivation, hoarseness, and difficulty swallowing; these symptoms are soon followed by severe abdominal pain, headache, numbness, nausea, and bloody diarrhoea; children may show additional narcotic symptoms with muscular twitching; work by Frohne and Pfänder has determined that it is the chewed seed, not the fruit pulp, that is responsible for the severe symptoms in poisoning by the berries.

8.3 Protein Kinase C Activation and Tumor Promotion Risk

The toxins mezerein and daphnetoxin are both present in the genus Daphne; daphnetoxin has a structure similar to mezerein with a phenyl-pentadienoyl component missing; they are both PKC activators but with different selectivity: mezerein exhibits antileukemic properties while daphnetoxin does not; mezerein is classified as a second-stage tumor promoter.

8.4 Contact Dermatitis

Mezereon (Daphne mezereum) is known to cause contact dermatitis through contact with its bark, fruits, leaves, and sap/juice. In the clinical trial of the Cortex Daphnes patch, 28.8% of patients in the Cortex Daphnes patch group reported treatment-related adverse events, the vast majority of which were mild-to-moderate skin irritation.

8.5 CYP Enzyme Interactions

A comprehensive review of the literature has revealed that daphnetin (DAP) has a promising pharmacological and safety profile and could be employed as a pharmaceutical moiety to treat a variety of illnesses including microbial infections, cancer, arthritis, hepatic damage, inflammation, and neurological anomalies. However, research into pharmacokinetic drug interactions at the level of specific CYP isoforms has been reported; studies on the effects of total flavonoid extracts and individual monomers of D. genkwa on CYP2C8 activity have been published (PubMed PMID 35621148), indicating a potential for metabolic drug interactions — though the clinical significance of such interactions has not been fully characterized in human studies.

8.6 Toxicity in Specific Populations and Regulated Status

In young children (toddlers), the symptoms following oral ingestion of plant parts are mainly vomiting and hypercatharsis after taking one or two parts of the plant orally; when more parts are eaten it will mostly cause death. Daphne mezereum and its preparations are not approved as dietary supplements or medicines in the European Union, United States, or most other major regulatory jurisdictions outside of China, where Cortex Daphnes (Zushima) is a registered traditional Chinese medicine. The internal use of crude Daphne plant material is not considered safe based on its established toxicological profile.

8.7 Safety of Isolated Daphnetin

In one animal study, no adverse effect of daphnetin was observed on serum markers and organs like liver, kidney, and small intestine. Despite initial insights, the precise mechanisms underlying the pharmacological activities of daphnetin remain largely unknown, and long-term human safety data for isolated daphnetin are absent from the available published literature.

Summary of Evidence Strength

Human/clinical evidence: Limited to one multicenter RCT for topical Cortex Daphnes patch in knee osteoarthritis, which demonstrated non-inferiority to topical indomethacin over 2 weeks, with a higher rate of local skin reactions. Prior to this RCT, only one low-quality randomized controlled trial in patients with knee OA had reported satisfactory clinical efficacy of Cortex Daphnes; the preparation had been widely used for symptomatic knee OA in China, but clinical evidence supporting its use remained scant.

Preclinical evidence: Broad and growing body of in vitro and animal model data for anti-inflammatory, antitumor, neuroprotective, hepatoprotective, and antimicrobial activities of constituent compounds (daphnetin, daphnoretin, genkwanin, genkwadaphnin, mezerein). The genus Daphne has been used for medicinal purposes for centuries, and multiple studies have confirmed a variety of biological and pharmacological effects attributed to several species by folk medicine.

Conclusion on translational status: Further scientific data on human clinical trials is needed to ensure the safety and efficacy of key constituents of Daphne in medicine. The gap between in vitro and animal data on one hand, and validated human clinical evidence on the other, is large for all applications except topical joint pain management in the Chinese traditional medicine context.

References

• Phytochemistry and Pharmacological Activities of the Diterpenoids from the Genus Daphne — PMC (2021)
• Clinical Efficacy of Cortex Daphnes (Zushima) Patch in Patients With Symptomatic Knee Osteoarthritis: A Multicenter Non-Inferiority Randomized Controlled Clinical Trial — Frontiers in Pharmacology / PMC (2021)
• The Molecular Effects Underlying the Pharmacological Activities of Daphnetin — Frontiers in Pharmacology / PMC (2024)
• Daphnetin: A Bioactive Natural Coumarin with Diverse Therapeutic Potentials — Frontiers in Pharmacology / PMC (2022)
• Phytochemical Profiling and Antioxidant Potential of Daphne mucronata Royle and Action Against Paracetamol-Induced Hepatotoxicity and Nephrotoxicity in Rabbits — PMC (2021)
• Daphnoretin Inhibits Glioblastoma Cell Proliferation and Metastasis via PI3K/AKT Signaling Pathway Inactivation — PMC (2024)
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• Daphnane Diterpenoids from Daphne genkwa Inhibit PI3K/Akt/mTOR Signaling and Induce Cell Cycle Arrest and Apoptosis in Human Colon Cancer Cells — PubMed (2020)
• Mezerein — Wikipedia
• Daphnin — Wikipedia
• Daphne mezereum — Wikipedia
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• The Molecular Effects Underlying the Pharmacological Activities of Daphnetin — Frontiers in Pharmacology (2024; full text)