IngredientsToxicodendron vernicifluum (formerly Rhus verniciflua), also known by the common name Chinese lacquer tree, is an Asian tree species of the genus Toxicodendron, native to China and the Indian subcontinent, and cultivated in regions of China, Japan, and Korea. The generic name of the species is derived from the Greek words toxikos, meaning "poison," and dendron, meaning "tree," while the specific name vernicifluum means "lacquer" in Latin. The plant is classified in the family Anacardiaceae — the sumac or cashew family.
The shift from the former name Rhus verniciflua to Toxicodendron vernicifluum in the 20th century underscores taxonomic progress, driven by genetic and morphological studies that grouped it with poison ivy relatives. In much of the scientific medical literature, the plant continues to be referenced by its older synonym Rhus verniciflua Stokes, abbreviated RVS. Other common names include poison sumac, Japanese lacquer tree, Japanese sumac, and varnish tree. In Japanese, the lacquer produced from it is called urushi, from which the name of the allergenic compound urushiol derives.
Toxicodendron vernicifluum is a deciduous tree growing to 15 m (49 ft) tall by 10 m (32 ft) wide. The trees grow up to 20 metres tall with large leaves, each containing from 7 to 19 leaflets (most often 11–13). The species is dioecious — individual flowers are either male or female, but only one sex is found on any one plant, so both male and female plants must be grown if seed is required.
The lacquer tree is mainly distributed in Shaanxi, Hubei, Sichuan, Chongqing, Gansu, Guizhou, and Yunnan provinces in China, and it is also distributed in other oriental countries and regions, such as Thailand, Vietnam, Japan, and the Korean Peninsula. The plants are born in sunny hillside forests at altitudes of 800–2800 metres, mostly wild but also cultivated.
The leaves, seeds, and resin of the Chinese lacquer tree are sometimes used in Chinese medicine for the treatment of internal parasites and for stopping bleeding. The sap of Rhus verniciflua is referred to as lacquer, and dried lacquer has been traditionally known in Oriental medicine to have the functions of removing extravasated blood, promoting blood circulation, and having efficacy against intestinal worms, abdominal pain, hyperacidity, coughs, tuberculosis, amenorrhea, constipation, diabetes mellitus, and malaria.
In modern supplement and pharmaceutical contexts, the plant material — most commonly the stem bark or heartwood — is processed into standardized extracts, typically administered as capsules. A critical processing step involves the removal of urushiol (the allergenic constituent) before clinical or supplemental use. A standardized extract of allergen-removed RVS (aRVS) has been manufactured based on thorough historical research, specified as fustin >13.0%, fisetin >2.0%, urushiol not detected. Extract from Rhus verniciflua Stokes free of the compound causing allergies (urushiol) is found in Korea, as powder or as a liquid extract.
The fruits of the lacquer tree have additional uses: the fruits of T. vernicifluum can also be processed to produce a waxy substance known as Japan wax, used for numerous purposes including varnishing furniture and producing candles.
Toxicodendron vernicifluum, the lacquer tree, has been used in China, Japan, and South Korea for thousands of years as a highly durable coating material and a traditional herbal medicine, containing medicinal ingredients with anti-tumor, anti-inflammatory, antiviral, and anti-rheumatic activities. There have been records of various parts of RVS used in medicine since ancient times in China. In Traditional Chinese Medicine (TCM), the dried lacquer resin was particularly prized for its blood-moving properties. Dried lacquer has been traditionally known in Oriental medicine to have the functions of removing extravasated blood, promoting blood circulation, and having efficacy against intestinal worms, abdominal pain, hyperacidity, coughs, tuberculosis, amenorrhea, constipation, diabetes mellitus, and malaria.
RVS was documented to be used for treating various stomach diseases, including tumor, in East Asia including Korea as early as the 15th century. Since the 15th century, it has also been used to treat stomach and uterine cancers in South Korea. In Korea, RVS has been used as a herbal medicine for the treatment of abdominal pain, including pain caused by stomach disorders such as gastritis, and as a hemostatic agent. Traditionally, this remedy has been used in Eastern Asia for the treatment of gastric problems, hepatic disorders, infectious diseases, and blood disorders.
Archaeological evidence of lacquer use in Japan dates back approximately 9,000 years, likely via exchanges with mainland Asia. The tree is indigenous to China and Korea and has certainly been cultivated in Japan at least since the 6th century. Buddhist monks who practiced Sokushinbutsu would use the tree's sap in their ceremony.
Within traditional Korean medicine theory, the plant's application to tumors and solid masses was conceptualized through the lens of blood stasis. Traditionally, Rhus verniciflua Stokes was considered to have the function of "breaking up blood stasis and purging hardness," and therefore it could be applied for cancer treatment. Preparations included decoctions of the bark and leaves, dried powders of the resin, and, more recently, standardized capsule extracts of the stem bark.
Gallic acid, fustin, fisetin, quercetin, butein, and sulfuretin are the main active constituents of R. verniciflua. RVS contains a wide variety of flavonoids and polyphenols, including fustin, fisetin, quercetin, butein, p-coumaric acid, kaempferol, sulfuretin, catechol, and ethyl gallate.
A more complete list of identified compounds from phytochemical screening includes: fisetin, fustin, sulfuretin, butein, butin, eriodictyol, morin hydrate, quercetin, kaempferol, and isoliquiritigenin. Additional phenolic compounds identified by HPLC and LC-MS include protocatechuic acid, p-hydroxybenzoic acid, caffeic acid, chlorogenic acid, p-coumaric acid, phloretin-2-O-glucoside, and kaempferol-3-O-glucoside.
Among these, fustin is quantitatively the most abundant. Fustin is generally found in the highest content, but research has shown that fustin has low anticancer activity compared to fisetin, which has the highest anticancer activity. These components are mostly flavonoid-based materials, and flavonoids such as fisetin and fustin play a role in protecting blood vessels or capillaries.
The sap contains the allergenic compound urushiol, which gets its name from this species' Japanese name urushi; "urushi" is also used in English as a collective term for all kinds of Asian lacquerware made from the sap of this and related Asian tree species. Among the characteristic compounds of R. verniciflua, urushiol is a catechol compound with two hydroxyl groups on the benzene ring and is composed of a long fatty-acid chain with 15 carbon atoms and a side-branch bonding structure. The oxidation and polymerization of urushiol in the tree's sap in the presence of moisture allows it to form a hard lacquer, which is used to produce traditional Chinese, Korean, and Japanese lacquerware.
The lacquer tree possesses significant economic value due to its capability to produce raw lacquer, lacquer wax, and lacquer oil. The wax obtained from the fruit (Japan wax) is compositionally distinct from the therapeutic extracts under study, which are typically derived from the heartwood or stem bark.
Compounds butein and sulfuretin are antioxidants and have inhibitory effects on aldose reductase and advanced glycation processes. Among the isolated flavonoids, fisetin, sulfuretin, butein, and butin significantly protected murine hippocampal HT22 cells against glutamate-induced neurotoxicity and attenuated reactive oxygen species (ROS) generation; these flavonoids also significantly maintained antioxidative defense systems, preserving the activities of superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GSH-Px), and the content of glutathione (GSH). Extracts of T. vernicifluum significantly scavenge DPPH free radicals in a dose-dependent manner; total phenol content ranged from 2.12 to 89.25%, and total flavonoid content from 1.02 to 15.62%; the methanolic bark extract exhibited higher DPPH scavenging activity, probably due to its higher total phenol and flavonoid content.
Research on the anti-inflammatory mechanism of sulfuretin has pointed to an induction of heme oxygenase-1 expression, inhibition of LPS-induced inducible nitric oxide synthase, inhibition of cyclooxygenase-2, and reduction of the expression of pro-inflammatory cytokines via down-regulation of NF-κB. In vivo, sulfuretin maintained joint integrity, a result underscored by radiologic and histopathologic evidence.
Rhus verniciflua Stokes is known to promote blood circulation by preventing blood stasis. Platelets are the primary cells that regulate circulation and contribute to the development of diverse cardiovascular diseases by aggregation and thrombosis. Studies assessed the antiplatelet activity of RVS: pretreatment of washed platelets with RVS heartwood extract blunted the aggregatory response of platelets to collagen. Fisetin, butein, and sulfuretin were identified as effective inhibitors of platelet aggregation induced by collagen, thrombin, and adenosine-5'-diphosphate; antiplatelet activities of all three compounds were concentration dependent, and fisetin had a longer in vitro duration of action compared with butein or sulfuretin. Extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase activation by collagen was prevented by fisetin, whereas butein and sulfuretin failed to inhibit ERK, and p38 activation was not affected by any of the compounds.
As a potential anti-diabetic agent, sulfuretin inhibits aldose reductase, diminishes formation of glycation end products, and protects against cytokine-induced beta-cell damage in experimentally induced diabetes. Inhibition of aldose reductase is of particular interest because overactivation of the polyol pathway, which the enzyme mediates, is implicated in diabetic complications including neuropathy and nephropathy.
The aurone sulfuretin and the flavonol fisetin emerged as potent competitive inhibitors of soluble epoxide hydrolase with IC₅₀ values of 8.8 ± 0.3 µM and 9.6 ± 0.8 µM, respectively, while the chalcone butein exhibited a distinct non-competitive mode of inhibition (IC₅₀ = 21.4 ± 1.5 µM). Soluble epoxide hydrolase is a target of interest in inflammation, hypertension, and pain signaling research.
Several experimental studies showed that flavonoids from RVS have effective anti-proliferative and apoptotic activities on various tumor cell lines, including human lymphoma, breast cancer, osteosarcoma, and transformed hepatoma cells. One study investigated the apoptotic effects of RVS chloroform-methanol fraction from an acetone extract (RCMF) on human osteosarcoma cells; PARP cleavage was closely associated with RCMF-induced apoptosis in these cells. In colorectal cancer cell research, raw lacquer extract has been studied for its interaction with mTOR and Akt signaling pathways.
The preponderance of laboratory-based research on T. vernicifluum has been conducted in cancer-relevant cell lines and rodent models. An extract of Toxicodendron vernicifluum has been shown to induce growth inhibition and apoptosis of hepatic tumor cells in cell culture. In an animal model of breast cancer, a new extraction method was applied to produce T. vernicifluum Stokes extract (TVSE) without urushiol but with higher levels of flavonoids such as fustin and fisetin; in this in vivo study, fifty BALB/c mice were acclimated and then injected with 4T1 murine mammary carcinoma cells in mammary fat pads; mice were then orally administered 0, 50, 100, 200, or 400 mg of TVSE/kg body weight per day for 20 days; TVSE reduced tumor volume and weight dose-dependently, and at doses above 100 mg/kg, the expression of Ki67 was significantly reduced and the number of TUNEL-positive apoptotic cells was significantly increased. These results suggest that TVSE is potentially beneficial for the suppression of breast cancer growth and its-associated lung metastasis. Overall, T. vernicifluum is potentially bioactive, as evidenced by antioxidant, anti-lung cancer, and antibacterial assays; further studies were targeted at the purification of novel compounds for clinical evaluation.
One clinical study investigated the feasibility of standardized RVS extract for metastatic colorectal cancer (mCRC), experimentally proven to have anticancer activities; from July 2006 to November 2007, patients with conventional chemotherapy-refractory mCRC were enrolled; after applying inclusion/exclusion criteria, 36 patients were eligible for the final analysis; overall survival and adverse events of patients treated with RVS in the aftercare period were determined. The median RVS administration period was 2.7 months, and the median overall survival for the entire population was 10.9 months (95% CI 5.6–16.1), with a 1-year survival rate of 44.4%, which the authors reported as compatible with external controls. This study was retrospective and uncontrolled in design and therefore represents preliminary, low-certainty evidence.
In an 82-year-old female gastric cancer patient case, orally administered Rhus verniciflua Stokes decreased the polypoid mass at the mid body and caused a slight decrease in the flat elevated lesion at the prepyloric antrum at 5 months after starting daily therapy with 900 mg. The biochemical parameters associated with liver and renal function were within the normal range, and no significant adverse effects from her RVS treatment were observed. This represents a single case report, which does not allow causal conclusions.
A 62-year-old Korean male patient with recurrent hepatocellular carcinoma after liver transplantation, refractory to doxorubicin, exhibited shrinkage of lung metastasis and nonhematologic toxicity at 5 months after receiving Rhus verniciflua Stokes three times a day with 450 mg capsules. This is again a single case report and carries the same limitations.
Two case studies of RVS for renal cancer were reported in 2010; in one case, RVS was administered three times a day with 450 mg capsules. These were published in Annals of Oncology as case reports.
A retrospective case series investigated the clinical feasibility of standardized allergen-removed RVS (aRVS) extract for advanced or metastatic adenocarcinoma of the ampulla of Vater; from July 2006 to April 2011, all patients with advanced AAV treated with aRVS extract alone were reviewed; after applying inclusion/exclusion criteria, 12 patients were eligible for the final analysis. The daily oral administration of 1350 mg (one 450-mg capsule, three times a day) of aRVS extract was prescribed.
The most methodologically advanced human study published to date is a prospective observational pilot study. This prospective observational pilot study enrolled patients with confirmed inoperable stage III or IV pancreatic cancer undergoing or scheduled to receive 5-fluorouracil-based or gemcitabine-based first-line chemotherapy with RVS treatment, followed up for up to 20 months; the primary endpoint was the safety profile of RVS assessed through adverse events; secondary endpoints included overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). The quality of the RVS extract was tested and monitored according to standards of the investigating site (fisetin >0.6%; urushiol not detected); RVS was prescribed by licensed and experienced traditional Korean medicine doctors at Kyung Hee University Medical Center at Gangdong; included patients received RVS extract at the typical dose of 1 or 2 capsules per administration, 2 or 3 times daily, 30 minutes after a meal. Previous retrospective studies and case reports have suggested anticancer potential in various cancer types, including pancreatic cancer. This pilot study — while prospective — lacks a randomized control arm, which substantially limits conclusions about efficacy.
The collective human evidence for T. vernicifluum as an anticancer agent consists primarily of retrospective case series, individual case reports, and one small prospective observational pilot study. None of the published human studies are randomized controlled trials (RCTs). Preclinical evidence is relatively extensive but limited to cell-culture and animal models. The current body of evidence is insufficient to establish efficacy in humans and should be characterized as preliminary.
Enormous animal studies have shown the potential of RVS against pro-inflammatory diseases, neurodegenerative diseases, diabetes, liver diseases, and chemical insults; at the molecular level, this medicinal plant has been shown to modulate diverse cell-signaling pathways. The anti-inflammatory evidence for the lacquer tree rests substantially on preclinical (in vitro and animal) data. Specifically, sulfuretin's effects on NF-κB, COX-2, and iNOS signaling have been demonstrated at the laboratory level, and its in vivo effects on joint integrity in arthritis models have been noted. One of the first studies reported that this aurone (sulfuretin) is active in rheumatoid arthritis. Human clinical trials for inflammatory conditions such as arthritis are not available in the peer-reviewed literature, and claims of clinical efficacy in this domain remain unsubstantiated by controlled human data.
As a potential anti-diabetic, sulfuretin inhibits aldose reductase, diminishes formation of glycation end products, and protects against cytokine-induced beta-cell damage in experimentally induced diabetes. Some animal experimental studies have revealed the efficiency of the plant in the treatment of liver diseases and diabetes. No controlled human clinical trials for diabetes or its complications attributable to T. vernicifluum have been identified in the peer-reviewed literature. The evidence is currently limited to in vitro enzyme inhibition assays and animal models.
The neuroprotective and anti-inflammatory activities of the methanolic extract of Rhus verniciflua Stokes were investigated with mouse hippocampal and microglial cells; bioactivity-guided isolation yielded 10 flavonoids including fisetin, sulfuretin, butein, and butin; among these, compounds fisetin, sulfuretin, butein, and butin significantly protected murine hippocampal HT22 cells against glutamate-induced neurotoxicity and attenuated reactive oxygen species generation. These findings are exclusively in vitro and in murine cell-line models. No human clinical trials evaluating lacquer tree extract for neurodegenerative or neuroprotective outcomes have been identified.
RVS heartwood may have cardiovascular protective activity by inhibiting platelet aggregation; the active constituents are fisetin, butein, and sulfuretin, and fisetin is orally effective against thrombosis in animal models. Rats orally administered 100 mg/(kg·day) fisetin for 7 days were resistant to arterial thrombosis, although the total extract of RVS heartwood exhibited little effect at a dose of 1000 mg/(kg·day). Evidence here is confined to in vitro platelet assays and a rat thrombosis model. No human data are available.
Among the extracts of T. vernicifluum, only the methanolic bark extract showed anti-lung cancer activity at an acceptable level, and it also exhibited higher DPPH scavenging and antimicrobial activity. The methanolic bark extract showed more significant antibacterial activity against MRSA; the in vivo antibacterial activity was further tested in a C. elegans model; MRSA treatment induced cell disruption, damage, and increased mortality of C. elegans compared to controls, and MBE treatment enhanced the survival of MRSA-infected C. elegans. Antimicrobial evidence is entirely preclinical.
The following dosages are drawn directly from published studies and should not be interpreted as recommendations:
The primary, established safety concern of the lacquer tree is urushiol, the catechol-based allergenic compound in its sap. All members of the Toxicodendron genus produce urushiol, a mixture of 3-n-alk-(en)-yl catechols with potent potential to cause allergic contact dermatitis (ACD); ACD is a type 4 hypersensitivity reaction mediated by Langerhans cells and T lymphocytes, resulting in a pruritic, possibly vesicular eruption in previously sensitized individuals. It is estimated that 50 to 75% of adults are allergic to urushiol, though variations can occur where T cells cannot recognize the presenting antigens and no immunologic response occurs.
Oral or parenteral exposure to certain contact allergens can elicit an eczematous skin reaction in sensitized individuals; this phenomenon has been called systemic contact dermatitis (SCD) and is relatively rare compared with classical contact dermatitis. Erythema multiforme in a photodistribution has been attributed to Toxicodendron vernicifluum, and the rash was reproduced by challenge with the drug and sunlight. Symptoms of allergic contact dermatitis from urushiol exposure vary from a mild annoyance to weeks of irritation and pain; occasionally, exposure can lead to nephropathy and even to fatal systemic anaphylaxis.
The clinical application of RVS has been limited because of the allergenic component urushiol, which causes severe contact dermatitis in sensitive individuals; therefore, urushiol, a mixture of several derivatives of catechol, must be removed from RVS prior to its pharmaceutical use.
All clinical studies of allergen-removed RVS used an urushiol-free extract, and the treatment has had no severe adverse effect; however, this is still controversial because more detailed confirmative works on safety will also be required to use this remedy clinically.
A formally published pharmacokinetic concern is the inhibition of hepatic cytochrome P450 enzymes by RVS and its constituents. Potential interactions between herbal extracts and the cytochrome P450 (CYP) system lead to serious adverse events or decreased drug efficacy; RVS and its constituents have been reported to have various pharmacological properties, and researchers have evaluated the inhibitory potential of RVS and its constituents on the major CYP isoforms. The effects of allergen-removed RVS (aRVS) standardized extract and major components, fustin and fisetin isolated from aRVS, were evaluated on CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 isoenzyme activity by a luminescent CYP recombinant human enzyme assay. RVS may contribute to herb-drug interactions when orally co-administered with drugs metabolized by CYP2C9, CYP2C19, and CYP1A2. This finding has been established in vitro but its clinical magnitude in humans has not been fully characterized.
Many of the species in this genus, including this one, are highly toxic and can also cause severe irritation to the skin of some people, whilst other species are not poisonous. Raw or unprocessed lacquer tree plant material — containing urushiol — should not be used as a dietary supplement or consumed orally. All clinical studies that have reported acceptable safety profiles specifically used preparations from which urushiol had been verified as undetectable. The quality of the RVS extract was tested and monitored according to the standards of the investigating site, requiring fisetin >0.6% and urushiol not detected.
Toxicodendron vernicifluum (lacquer tree, RVS) is a well-characterized botanical with a documented multi-millennia history of use in East Asian traditional medicine systems, particularly for gastrointestinal conditions, hemostasis, and — more recently codified — tumors. Its phytochemical profile is rich in biologically active flavonoids, with fisetin, fustin, sulfuretin, and butein being the most-studied.
Modern science has provided the scientific basis for the use of Rhus verniciflua Stokes against such disorders and diseases; various chemical constituents have been identified from this plant, including phenolic acids and flavonoids. However, the translational gap between preclinical findings and validated human outcomes remains substantial. The totality of human evidence consists of retrospective case series, individual case reports, and a single small prospective observational pilot study — all conducted in South Korea, all in advanced cancer populations, and none with a randomized control arm. The evidence across all indicated health areas — including oncology, inflammation, diabetes, and neuroprotection — must be characterized as preliminary. No regulatory authority (FDA, EMA, or comparable bodies) has approved any lacquer tree extract for any medical indication.
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