Network toxicology, molecular docking technology, and experimental verification revealed the mechanism of cantharidin-induced testicular injury in mice.

As a protein kinase inhibitor, cantharidin (CTD) exhibits antitumor activities. However, CTD is highly toxic, thereby limiting clinical applications. Moreover, relatively few studies have investigated CTD-induced reproductive toxicity, thus the underlying mechanism remains unclear. In this study, the toxic effects of CTD on mouse testis were confirmed in vivo and the potential mechanism was predicted by network toxicology (NT) and molecular docking technology. Proteins involved in the signaling pathways and core targets were verified. The results showed that different concentrations of CTD induced weight loss increased the testicular coefficient, and caused obvious pathological damage to testicular cells. The NT results showed that the main targets of CTD-induced testicular injury (TI) included AKT1, Caspase 3, Bcl-2, and Bax. The results of pathway enrichment analysis showed that CTD-induced TI was closely related to apoptosis and the PI3K/AKT and HIF-1 signaling pathways. Molecular docking methods confirmed high affinity between CTD and key targets. Western blot analysis showed that CTD inhibited expression of PI3K, AKT, and the anti-apoptotic protein Bcl-2, while promoting expression of the pro-apoptotic proteins Bax and Caspase 3. These results suggest that CTD-induced TI involves multiple targets and pathways, and the underlying mechanism was associated with inhibition of the apoptosis-related PI3K/AKT signaling pathway.

A novel approach combining network pharmacology and experimental validation to study the protective effect of ginsenoside Rb1 against cantharidin-induced hepatotoxicity in mice.

Cantharidin (CTD) is a widely used anticancer compound, but its clinical use is mainly limited due to hepatotoxicity. Ginsenoside Rb1 (GRb1) shows potential hepatoprotective effects. Nonetheless, the protective effect and underlying mechanism of GRb1 against CTD-induced hepatotoxicity in mice have not been investigated. This study aims to elucidate the effect and mechanism of GRb1 on CTD-induced hepatotoxicity using network pharmacology and in vivo experiments. Network pharmacology studies have shown that 263 targets were the main mechanisms by which GRb1 alleviates CTD-induced hepatotoxicity. KEGG enrichment analysis revealed that 75 hub genes were mainly enriched in TNF, IL-17 and apoptosis signalling pathways. Molecular docking analysis showed that GRb1 exhibited high affinity with Akt1, Tnf, Il6, Bcl2 and Caspase3. In addition, results from animal studies demonstrated that GRb1 could ameliorate CTD-induced hepatotoxicity by inhibiting protein expression of Caspase-3, Caspase-8, Bcl-2/Bax, GRP78, ATF6, ATF4, CHOP, IRE1α and PERK. This research revealed the mechanism of GRb1 against CTD-induced hepatotoxicity by inhibiting apoptosis and endoplasmic reticulum stress (ERS) and it may provide a scientific rationale for the potential use of GRb1 in the treatment of hepatotoxicity induced by CTD.

In vitro immune-depression and anti-inflammatory activities of cantharidin on gilthead seabream (Sparus aurata) leucocytes activated by λ-carrageenan.

Cantharidin is a natural compound with known therapeutic applications in humans. The aim of this study was to investigate the in vitro effects of cantharidin on gilthead seabream (Sparus aurata) head kidney leucocytes (HKL) stimulated with λ-carrageenan. HKLs were incubated for 24 h with cantharidin (0, 2.5 and 5 µg mL-1) and λ-carrageenan (0 and 1000 µg mL-1). The results showed that HKL viability only decreased by 15.2% after incubated with 5 µg mL-1 of cantharidin and λ-carrageenan. Cantharidin increased the peroxidase activity of HKLs only when incubated in combination with λ-carrageenan. Besides this, cantharidin inhibited the respiratory burst and phagocytic activities. Furthermore, cantharidin induced morphological changes in HKLs (apoptotic and vacuolization signs) that were enhanced when incubated with λ-carrageenan. Considering the analysis of the selected gene expression studied in HKLs [NF-κB subunits (rela, relb, crel, nfkb1, nfkb2), proinflammatory cytokines (il1b, tnfa), anti-inflammatory cytokines (il10, tgfb) and caspases (casp1, casp3, casp8, casp9)], although λ-carrageenan up-regulated the expression of the proinflammatory gene il1b, λ-carrageenan and cantharidin down-regulated its expression in HKLs. In addition, cantharidin up-regulated casp3 and casp9 expression. The casp3 and casp9 gene expression was down-regulated while casp1 gene expression was up-regulated in HKLs incubated with both cantharidin and λ-carrageenan. All the effects of cantharidin are related to its inhibitory effect on protein phosphatases, which induce apoptosis at long exposure times, and minimize the effects of λ-carrageenan. The present results provide detailed insight into the immune-depressive and anti-inflammatory properties of cantharidin on immune cells, which could be of interest to the aquaculture sector.

Lipidomics reveals serum lipid metabolism disorders in CTD-induced liver injury.

BACKGROUND: Cantharidin (CTD), the main toxic component of Mylabris, has been extensively used for tumor treatment in recent years. CTD-induced liver toxicity has attracted significant interest in clinic. METHODS: In this study, biochemical parameters and liver pathological changes were analyzed after CTD was administered to mice by gavage. Subsequently, a lipidomic approach was used to investigate serum lipid metabolism disorders, and the mechanism underlying CTD-induced liver injury in mice was explored. RESULTS: The results showed that the levels of TC and LDL-C were significantly increased after CTD intervention. Besides, pathological results showed inflammatory cell infiltration and hepatocyte necrosis in the liver. Furthermore, lipidomics found that a total of 18 lipid metabolites were increased and 40 were decreased, including LPC(20:4), LPC(20:3), PC(22:6e/2:0), PE(14:0e/21:2), PC(18:2e/22:6), glycerophospholipids, CE(16:0), CE(18:0) Cholesterol esters and TAG(12:0/12:0/22:3), TAG(16:1/16:2/20:4), TAG(18:1/18:1/20:0), TAG(16:2/18:2/18:2), TAG(18:0/18:0/20:0), TAG(13:1/19:0/19:0) glycerolipids. Metabolic pathway analysis found that glycerophospholipid, glycerol ester and glycosylphosphatidylinositol (GPI)-anchored biosynthetic metabolic pathways were dysregulated and the increase in PE caused by glycophoric metabololism and GPI may be the source of lipid metabolism disorders caused by CTD. Overall, the present study provided new insights into the mechanism of CTD-induced liver injury and increased drug safety during clinical application.

Avoiding cantharidin through ionotropic receptors.

The discernment and aversion of noxious gustatory stimuli profoundly influence homeostasis maintenance and survival of fauna. Cantharidin, a purported aphrodisiac, is a monoterpenoid compound secreted by many species of blister beetle, particularly by the Spanish fly, Lytta vesicatoria. Although the various advantageous functions of cantharidin have been described, its taste analysis and toxic properties in animalshave been rarely explored. Our study using Drosophila melanogaster examines the taste properties of cantharidin along with its potential hazardous effect in the internal organs of animals. Here, we find that cantharidin activates bitter taste receptors. Our findings show that specific ionotropic receptors (IR7g, IR51b, and IR94f) in labellar bitter-sensing neurons, along with co-receptors IR25a and IR76b, are responsible for detecting cantharidin. By introducing the IR7g and IR51b in sweet and bitter neurons, naturally expressing IR76b and IR25a, we show that these genes are sufficient for cantharidin perception. Moreover, we witness the deleterious ramifications of cantharidin on survival and visceral integrities, shedding light on its hazardous effect.

Application of cantharidin, retinoic acid cream and salicylic acidy in multiple palmoplantar warts.

OBJECTIVE: Multiple palmoplantar warts, caused by human papillomavirus (HPV) infection, were investigated for clinical efficacy using cantharidin, retinoic acid cream, and salicylic acid cream. METHODS: A total of 110 patients with multiple palmoplantar warts were enrolled. The experimental group (54 cases) received a 1:1:1 combination (CRS) of 0.25% cantharidin, 0.1% retinoic acid cream, and 5% salicylic acid, applied with pressurized encapsulation for 8 h every night, three times per week. The control group (56 cases) underwent conventional liquid nitrogen freezing. Monthly follow-ups assessed cure rate, effective rate, dermatological life quality index (DLQI), visual analog scale (VAS), and cost, with evaluations conducted after 3 months. RESULTS: The treatment group exhibited a cure rate of 85.19% and a total effective rate of 96.30%, surpassing the control group with rates of 39.29% and 51.79%, respectively (p < 0.05). The treatment group's DLQI score (1.84 ± 1.06) was significantly lower than the control group's score (6.04 ± 1.78) (p = 0.0005). Additionally, the treatment group's VAS score (1.84 ± 1.06) was notably lower than the control group's score (8.56 ± 1.07) (p < 0.0001). The treatment group's total cost (43.20 ± 2.85) was markedly lower than the control group's cost (206.38 ± 90.81), with a statistically significant difference (p < 0.0001). CONCLUSION: The combination of cantharidin, retinoic acid cream, and salicylic acid with local encapsulation is a safe, effective, economical, and convenient treatment method for multiple palmoplantar warts, exhibiting few side effects and showing promise.

Design and synthesis of cantharidin derivative DCZ5418 as a TRIP13 inhibitor with anti-multiple myeloma activity in vitro and in vivo.

Natural product cantharidin can inhibit multiple myeloma cell growth in vitro, while serious adverse effects limited its clinical application. Therefore, the structural modification of cantharidin is needed. Herein, inspired by the structural similarity of the aliphatic endocyclic moiety in cantharidin and TRIP13 inhibitor DCZ0415, we designed and synthesized DCZ5418 and its nineteen derivatives. The molecular docking study indicated that DCZ5418 had a similar binding mode to TRIP13 protein as DCZ0415 while with a stronger docking score. Moreover, the bioassay studies of the MM-cells viability inhibition, TRIP13 protein binding affinity and enzyme inhibiting activity showed that DCZ5418 had good anti-MM activity in vitro and definite interaction with TRIP13 protein. The acute toxicity test of DCZ5418 showed less toxicity in vivo than cantharidin. Furthermore, DCZ5418 showed good anti-MM effects in vivo with a lower dose administration than DCZ0415 (15 mg/kg vs 25 mg/kg) on the tumor xenograft models. Thus, we obtained a new TRIP13 inhibitor DCZ5418 with improved safety and good activity in vivo, which provides a new example of lead optimization by using the structural fragments of natural products.

Cantharidin.

Cantharidin is the toxic component of blister beetles of the genus Epicauta. Cantharidin is a potent vesicant which causes blisters, erosions, and ulcerations in the gastrointestinal and urinary tracts, and can cause myocardial necrosis. Blister beetles are found over most of North America and specifically contaminate alfalfa at harvest. History of alfalfa feeding, with colic, dysuria, hypocalcemia, and hypomagnesemia are suggestive of blister beetle toxicosis. Myocardial damage causes increased serum cardiac troponin 1. Tentative diagnosis can be made by finding the beetles in feed or ingesta. Definitive diagnosis requires detection of cantharidin in urine or gastric contents. Treatment involves ending exposure, decreasing absorption, controlling pain, using gastroprotectants, and fluids and electrolyte replacement. Prognosis is guarded to poor.

Cantharidin-induced toxic injury, oxidative stress, and autophagy attenuated by Astragalus polysaccharides in mouse testis.

Cantharidin (CTD) is a chemical constituent derived from Mylabris and has good antitumor effects, but its clinical use is restricted by its inherent toxicity. However, few researches have reported its reproductive toxicity and mechanisms. This study aims to assess CTD's toxicity on mouse testes and the protective effect of Astragalus polysaccharides (APS). Briefly, biochemical analysis, histopathology, transmission electron microscopy, immunohistochemistry, and Western blotting were used to evaluate the oxidative damage of mouse testicular tissue after exposure to CTD and treatment by APS. Our research suggests a dramatic decrease in testicular index and serum testosterone levels after CTD exposure. The testis showed obvious oxidative damage accompanied by an increase in mitochondrial autophagy, the Nfr2-Keap1 pathway was inhibited, and the blood-testis barrier was destroyed. Notably, these changes were significantly improved after APS treatment. The internal mechanisms of APS ameliorate CTD-induced testicular oxidative damage in mice may be closely connected to regulatory the Nrf2-Keap1 signaling pathway, restraining autophagy, and repairing the blood-testis barrier, providing theoretical support for further study on the reproductive toxicity mechanism of CTD and clinical treatments to ameliorate it.

Cantharidin Topical Solution 0.7%: First Approval.

Cantharidin (YCANTH™) is a proprietary drug-device combination product containing a formulation of cantharidin 0.7% topical solution (a vesicant naturally derived from blister beetles) delivered via a single-use applicator that has been developed by Verrica Pharmaceuticals Inc. for the treatment of molluscum contagiosum and is also being developed for the treatment of warts. In July 2023, YCANTH™ (cantharidin 0.7% topical solution) was approved for the topical treatment of molluscum contagiosum in adult and pediatric patients 2 years of age and older in the USA. This article summarizes the milestones in the development of cantharidin 0.7% topical solution leading to this first approval for the topical treatment of molluscum contagiosum in adult and pediatric patients 2 years of age and older.

Cantharidin and sodium fluoride attenuate the negative inotropic effects of carbachol in the isolated human atrium.

Carbachol, an agonist at muscarinic receptors, exerts a negative inotropic effect in human atrium. Carbachol can activate protein phosphatases (PP1 or PP2A). We hypothesized that cantharidin or sodium fluoride, inhibitors of PP1 and PP2A, may attenuate a negative inotropic effect of carbachol. During bypass-surgery trabeculae carneae of human atrial preparations (HAP) were obtained. These trabeculae were mounted in organ baths and electrically stimulated (1 Hz). Force of contraction was measured under isometric conditions. For comparison, we studied isolated electrically stimulated left atrial preparations (LA) from mice. Cantharidin (100 µM) and sodium fluoride (3 mM) increased force of contraction in LA (n = 5-8, p < 0.05) by 113% ± 24.5% and by 100% ± 38.2% and in HAP (n = 13-15, p < 0.05) by 625% ± 169% and by 196% ± 23.5%, respectively. Carbachol (1 µM) alone exerted a rapid transient maximum negative inotropic effect in LA (n = 6) and HAP (n = 14) to 46.9% ± 3.63% and 19.4% ± 3.74%, respectively (p < 0.05). These negative inotropic effects were smaller in LA (n = 4-6) and HAP (n = 9-12) pretreated with 100 µM cantharidin and amounted to 58.0% ± 2.27% and 59.2% ± 6.19% or 3 mM sodium fluoride to 63.7% ± 9.84% and 46.3% ± 5.69%, (p < 0.05). We suggest that carbachol, at least in part, exerts a negative inotropic effect in the human atrium by stimulating the enzymatic activity of PP1 and/or PP2A.

Integrative analysis of the molecular signature of target genes involved in the antitumor effects of cantharidin on hepatocellular carcinoma.

BACKGROUND: Cantharidin (CTD) is the active ingredient of Chinese medicine, which has been traditionally used in multiple cancers treatment, especially in hepatocellular carcinoma (HCC). However, a comprehensive analysis of the CTD-related molecular mechanism is still necessary to understand its functions in HCC treatment. This study aimed to reveal the novel molecular targets and regulatory networks of CTD in HCC. METHODS: A model of H22 tumour-bearing mice was constructed, and the function of CTD in tumour growth was evaluated. An integrated approach of CTD associated transcriptional profiling and biological systems analysis was used to identify key regulators involved in antitumour pathways. The identified differential expression patterns were supported by the results of Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyse, and by protein-protein interaction (PPI) network construction. The relationships between gene expression and tumour immunity were evaluated using Tumour Immune Estimation Resource (TIMER). Prognostic value was analyzed with Kaplan-Meier plotter. RESULTS: In the present study, the therapeutic effect of CTD on HCC was evaluated in vivo. We obtained the CTD-related transcriptional profiles, systematically and intuitively illustrated its possible pharmacological mechanisms in HCC through multiple targets and signalling pathways. These results revealed that the CTD-related differentially expressed genes were involved in autophagy, transcription factors (TFs) related transcriptional regulation, fatty acid metabolism and immune response in HCC. We found that MAPT, TOP2A, CENPF and MEFV were hub genes of CTD targets involved in autophagy regulation. Totally, 14 TFs have been confirmed to be critical for transcriptional regulation, and 33 TF targets were identified as the hub genes in transcriptional mis-regulation pathway in cancer. These TFs were associated with the immune response and immune cell infiltration. In addition, the downregulated genes were significantly enriched in metabolic regulation pathways, especially fatty acid metabolism after CTD treatment. Furthermore, the network of CTD associated miRNAs with these fatty acid metabolism-related targets was constructed in HCC. CONCLUSIONS: Taken together, our results comprehensively elucidated that CTD could act on multiple targets in HCC therapy, affecting autophagy, transcriptional regulation, the immune response and fatty acid metabolism. Our results provide a foundation for the study of the molecular mechanistic of CTD and its clinical application in the treatment of HCC.

The cranial apparatus glands of the canthariphilous Pyrochroa coccinea (Coleoptera: Pyrochroidae: Pyrochroinae), and their implications in sexual behaviour.

Some Pyrochroidae species are known as "canthariphilous" for their attraction to cantharidin (CTD), a toxic terpene with anti-predatory effects, produced in nature by only two beetle families (Meloidae and Oedemeridae). It has been demonstrated that males of Neopyrochroa flabellata ingesting CTD are positively selected by females. Indeed, the compound is re-emitted from a glandular cranial apparatus as secretions that are licked up by females during courtship behaviour, inducing copulation. Herein, we provide the first description of the glands associated to the cranial apparatus of male Pyrochroinae using the European species Pyrochroa coccinea as a model. Morphological analyses show that the cranial apparatus consists of a concave pit lined with short setae retaining secretions emitted through numerous glandular pores. Ultrastructural investigations reveal the presence of two different class 3 glands (Gl.A and Gl.B), intermixed at the level of the pit but exhibiting distinct features. Gl.A are mainly characterised by short conducting canals, rounded nuclei and electrondense vesicles while Gl.B are characterised by long conducting canals, irregular nuclei, vesicles containing a particulate substance and a multifolded plasma membrane. Observations of sexual behaviour are also reported for P. coccinea and compared to N. flabellata, confirming the involvement of cranial apparatus secretions in courtship behaviour.

YCANTHTM (Cantharidin) Topical Solution.

YCANTHTM (cantharidin) topical solution has been approved recently for the treatment of molluscum contagiosum (MC) in children (aged ≥2 years) and adults. It works by activating serine proteases that lead to blistering and inflammation, promoting shedding of infected cells and viral clearance. In two phase-3, randomized, double-blind, vehicle-controlled trials of similar design, VP-102 (a drug-device combination, containing cantharidin 0.7% w/v and inactive ingredients, such as gentian violet, acetone, and denatonium benzoate, administered with an applicator) was investigated for the treatment of MC. VP-102 and vehicle were applied topically once every 21 days until complete clearance of lesions was observed, or for up to four treatments. Cantharidin demonstrated efficacy in achieving the primary outcome, at day 84/visit 4 (Cantharidin Application in Molluscum Patients [CAMP-1], VP-102: 46% [73/160], vehicle: 18% [19/106]; and CAMP-2, VP-102: 54% [81/150], vehicle: 13% [15/112]). Common adverse events were mild to moderate, such as lesions at the site of application, pruritus, and pain. The recommended regimen of cantharidin topical solution is its application once every 21 days until complete clearance of lesions is observed, or up to four treatments.

Cantharidin induces apoptosis of human triple negative breast cancer cells through mir-607-mediated downregulation of EGFR.

BACKGROUND: Triple negative breast cancer (TNBC) is a major subtype of breast cancer, with limited therapeutic drugs in clinical. Epidermal growth factor receptor (EGFR) is reported to be overexpressed in various TNBC cells. Cantharidin is an effective ingredient in many clinical traditional Chinese medicine preparations, such as Delisheng injection, Aidi injection, Disodium cantharidinate and vitamin B6 injection. Previous studies showed that cantharidin had satisfactory pharmacological activity on a variety of tumors. In this study, we aimed to study the therapeutic potential of cantharidin for TNBC treatment by targeting EGFR, and expound its novel regulator miR-607. METHODS: The effect of cantharidin on breast cancer in vivo was evaluated by 4T1 mice model. Then the effects of cantharidin on TNBC cells was assessed by the MTT, colony formation, and AnnexinV-PE/7AAD staining. Cantharidin acts on EGFR were verified using the cell membrane chromatography, RT-PCR, Western blotting, MTT, and so on. Mechanistic studies were explored by dual-luciferase report assay, RT-PCR, western blotting, and immunofluorescence staining assay. RESULTS: Cantharidin inhibited TNBC cell growth and induce apoptosis by targeting EGFR. miR-607 was a novel EGFR regulator and exhibited suppressive functions on TNBC cell behaviors. Mechanistic study showed that cantharidin blocked the downstream PI3K/AKT/mTOR and ERK/MAPK signaling pathway. CONCLUSION: Our results revealed that cantharidin may be served as a potential candidate for TNBC treatment by miR-607-mediated downregulation of EGFR.

Cantharidin-Based Verbenone Derivatives as a Novel Insecticide against Plutella xylostella: Design, Synthesis, Insecticidal Activity Evaluation, and 3D QSAR Study.

The diamondback moth is a detrimental insect pest of brassicaceous crops which was among the first crop insects to be reported as DDT resistant. It has since proven to be significantly resistant to nearly every synthetic insecticide used in the field in many crucifer-producing regions. Due to insecticide control failures in some parts of the world, economically viable crucifer production is now all but impossible. As a result, there has been an increasing effort to identify new compounds with strong pesticidal activity. Cantharidin is one such compound that has been shown to be highly effective against a variety of insect pests. However, its chemical synthesis and potential toxicity to non-target organisms have been a major source of concern. Herein, using rational design approaches, a new series of cantharidin-based verbenone derivatives were synthesized and evaluated for their insecticidal activities against the diamondback moth. Among different compounds screened, compounds 6a, 6h, 6i, and 6q emerged as the most potent compounds exhibiting 100% mortality at a concentration of 100 mg/L after four days. These compounds demonstrated a good anti-feeding effect against the diamondback moth on cabbage leaves. Subsequently, a 3D QSAR study was carried out to identify the key structural features of the synthesized compounds and their correlation with insecticidal activity.

Investigation of sex expression profiles and the cantharidin biosynthesis genes in two blister beetles.

Cantharidin (CTD) is a well-established defensive toxin synthesized by blister beetles, displaying both therapeutic potential and toxicity. Among these beetles, Hycleus cichorii and Hycleus phaleratus are the two most commercially significant species due to their capacity to produce CTD in males. In this investigation, we conducted a gene expression profiling analysis of male and female individuals of these two species, utilizing the Illumina Hiseq4000 platform. We identified 7,983 expressed genes, including 2,823 differentially expressed genes (DEGs) shared by both male and female blister beetles. Nineteen genes related to CTD biosynthesis in the terpenoid backbone biosynthesis pathway were identified, including hydroxymethylglutaryl-CoA reductase (HMGR; EC:1.1.1.34), which demonstrated a significant correlation with CTD content. Furthermore, hydroxymethylglutaryl-CoA synthase (HMGS; EC:2.3.3.10) and isopentenyl-diphosphate Delta-isomerase (IDI; EC:5.3.3.2) were also found to be significantly up-regulated in males. Comparative analysis revealed that NADP+-dependent farnesol dehydrogenase (FOHSDR; EC:1.1.1.216) and farnesyl diphosphate synthase (FDPS; EC:2.5.1.1) had the highest copy number in these beetles, significantly higher than the copy number of the other four non-Meloidae insects. The analysis of the protein-protein interaction network of genes related to CTD biosynthesis revealed that the acetyl-CoA C-acetyltransferase (ACAT; EC:2.3.1.9) gene was the central gene, exhibiting greater expression in male blister beetles than in females. This study offers novel insights into the mechanisms of CTD biosynthesis in blister beetles and enhances our comprehensions of the association between particular genes and CTD content.

Cantharidin analogue alleviates dextran sulfate sodium-induced colitis in mice by inhibiting the activation of NF-κB signaling.

Ulcerative colitis is a chronic inflammatory disease with a remitting-relapsing clinical course, it has evolved into a global burden given its high incidence worldwide. Cantharidin (CTD) derivatives are a class of compounds whose structures characterized with a 7-oxabicyclo [2.2.1]heptane core. Though potent cytotoxicity CTD and its derivatives showed, their clinical usage as anti-cancer drugs was limited by the toxicity in organs. In order to find new CTD analogues with good activity and lower toxicity, 21 CTD analogues with or without alkynyl substitution at C5 position of 7-oxabicyclo [2.2.1]heptane core were synthesized, some compounds showed better in vitro anti-inflammatory activity compared to CTD and norcantharidin (NCTD). Based on the structure-activity relationship results of in vitro experiment, analogue 3i was chosen for further study. Results from the acute toxicity in mice showed that 3i was hypotoxic with the single-dose MTD (maximum tolerated dose) for oral administration is over 1852 mg/kg, at least 35-fold lower than that of NCTD. Mechanism study indicated that 3i could potently inhibit TNF-α induced activation of NF-κB signaling by down-regulation the expression levels of phosphor- IKK, IκBα, and NF-κB p65, and alleviated dextran sulfate sodium-induced colitis in mice. This study indicated that CTD analogues with alkynyl substitution at C5 position of 7-oxabicyclo [2.2.1]heptane core is a kind of new compounds with good anti-inflammatory activity and lower toxicity in vivo, and might be used as therapeutic agents for inflammatory diseases.